Co-reporter:Fangxu Jia, Qing Yang, Xiuhong Liu, Xiyao Li, Baikun Li, Liang Zhang, and Yongzhen Peng
Environmental Science & Technology March 21, 2017 Volume 51(Issue 6) pp:3260-3260
Publication Date(Web):February 27, 2017
DOI:10.1021/acs.est.6b05761
Sludge aggregation and biofilm formation are the most effective approaches to solve the washout of anammox microorganisms. In this study, the structure and composition of EPS (extracellular polymeric substances) were investigated to elucidate the factors for the anammox aggregation property. Anammox sludge taken from 18 lab-scale and pilot-scale reactors treating different types of wastewater was analyzed using EEM-PARAFAC (excitation–emission matrix and parallel factor analysis), FTIR (Fourier transform infrared spectroscopy) and real-time PCR combined with multivariate statistical analysis. The results showed that slime and TB-EPS (tightly bound EPS) were closely related with water quality and sludge morphology, and could be used as the indicators for anammox microbial survival ability and microbial aggregate morphology. Furthermore, slime secreted from anammox bacterial cells may be exhibited higher viscosity to the sludge surface and easily formed the gel network to aggregate. Large amounts of hydrophobic groups of protein in TB-EPS promoted the microbial aggregation. The mechanisms of anammox aggregation explored in this study enhanced the understanding of anammox stability in wastewater treatment processes.
Co-reporter:Wenlong Liu, Qing Yang, Bin Ma, Jun Li, Linna Ma, Shuying Wang, and Yongzhen Peng
Environmental Science & Technology April 4, 2017 Volume 51(Issue 7) pp:4001-4001
Publication Date(Web):March 6, 2017
DOI:10.1021/acs.est.6b04598
Rapid start-up of partial nitrification is of great significance for subsequent denitrification and the anammox process; however, slow nitritation hinders the application of these processes. The current study presents a novel strategy for achieving nitritation using aerobic starvation and controlling sludge retention time (SRT). Activated sludge with a high level of complete nitrification was introduced into an aerated reactor without feeding to start the aerobic starvation. The results showed that nitritation was rapidly achieved, while the shorter SRT (15 days) guaranteed the stability of nitritation with an average nitrite accumulation ratio (NAR) of more than 95%. The activity recovery rates of ammonium-oxidizing bacteria (AOB; from 0.20 ± 0.00 d–1 to 0.29 ± 0.08 d–1) were higher than those of nitrite-oxidizing bacteria (NOB; −0.11 ± 0.02 d–1 to 0.16 ± 0.05 d–1) during the reactivation periods. Furthermore, the transcriptional responses of amoA and hao mRNA after aerobic starvation were faster than that of the nxrB gene, which explained the fast occurrence of nitritation after the aerobic starvation period. The quantitative real-time PCR (qPCR) analysis showed that the cell number of nitrifying bacteria remained stable during the starvation process, whereas the AOB population gradually became dominant over that of NOB in the reactivation period. These observations strongly supported the feasibility of accelerating the establishment of nitritation using aerobic starvation.
Co-reporter:Yandong Yang;Liang Zhang;Hedong Shao
Frontiers of Environmental Science & Engineering 2017 Volume 11( Issue 2) pp:
Publication Date(Web):2017 April
DOI:10.1007/s11783-017-0911-0
Co-reporter:Shenbin Cao, Rui Du, Baikun Li, Shuying Wang, Nanqi Ren, Yongzhen Peng
Chemical Engineering Journal 2017 Volume 326(Volume 326) pp:
Publication Date(Web):15 October 2017
DOI:10.1016/j.cej.2017.06.066
•High nitrite production increased with NTR achieving at around 90%.•PD effluent was suitable for the feeding source of ANAMMOX process.•External carbon demand for PD was reduced after domestic wastewater addition.•Specific NO3−-N reduction rate was as high as 4.56 g N/g VSS/d.•Thauera genus responsible for nitrite production was dominated with 54.9–72.9%.Partial-denitrification (PD, NO3−-N → NO2−-N) has been successfully developed to produce nitrite (NO2−) with acetate as the sole carbon source. In this study, a PD sequencing batch reactor (SBR) fed with high-nitrate (NO3−: 1000 mg N/L) was firstly developed with carbon source obtained from domestic wastewater (NH4+: 59.3 mg N/L, chemical oxygen demand (COD): 186.6 mg/L) as well as a small quantity of external organic matter. The results showed that PD was not degenerated with domestic wastewater addition, and a high nitrite production was still achieved with the nitrate-to-nitrite transformation ratio (NTR) maintained at 90% in the 173-days operation period. By optimizing the nitrate and domestic wastewater feeding volume as well as external carbon dosage, the PD effluent was suitable for ANAMMOX process with a NO2−-N/NH4+-N of 1.46 and COD/NO2−-N of 1.32 obtained under the influent volume of domestic wastewater of 2.8 L, as well as nitrate of 0.4 L, and the external carbon demand was reduced to COD/NO3−-N of 1.7. Nitrate reduction rate was fit to Monod kinetics, with a maximum specific NO3−-N reduction rate of 4.56 g N/g VSS/d and nitrate half-saturation constant of 6.9 mg N/L, respectively. High-throughput sequencing analysis revealed that the diversity of microbial communities was increased with the domestic wastewater added, but the denitrifiers of Thaura genus that was responsible for high nitrite production was still dominant in PD reactor with a percentage of 54.9–72.9%. This study indicated that the high-nitrate and domestic wastewater could be simultaneously treated via the novel PD-ANAMMOX process in a cost-effective way.Download high-res image (105KB)Download full-size image
Co-reporter:FangZhai Zhang, Yongzhen Peng, Lei Miao, Zhong Wang, Shuying Wang, Baikun Li
Chemical Engineering Journal 2017 Volume 313(Volume 313) pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.cej.2016.12.105
•Simultaneous nitritation, Anammox and denitrification was achieved in a SBR.•The intermittent aeration operation mode was investigated.•The EEM was used to detect DOM in a typical operation cycle for the first time.•A mature landfill leachate without diluted was used in this study.•TN removal efficiency of 99 ± 0.1% was obtained.Mature landfill leachate is difficult to be treated due to its complex composition, high concentration of ammonia, and low carbon/nitrogen ratio (C/N). Simultaneous partial nitrification, Anammox and denitrification (SNAD) with intermittent aeration was developed to achieve nitrogen removal from mature landfill leachate. An ammonia conversion efficiency of 99.3 ± 0.3% and total nitrogen (TN) removal efficiency of 99 ± 0.1% were obtained under the influent NH4+-N, SCOD and TN of 1950 ± 250 mg/L 1900 ± 200 mg/L and 2300 ± 75 mg/L, respectively. Full utilization of carbon source and high efficient Anammox were two significant factors in SNAD process. Based on the nitrogen balance, the nitrogen removal contribution was 77.1% for Anammox, and 15.6% for denitrification. Three dimensional excitation-emission matrix (EEM) fluorescence spectroscopy was used to detect dissolved organic matter (DOM) in a typical operation cycle for the first time, demonstrating that DOM increased during the anoxic phase and facilitated the reduction of excess NO3--N by denitrification. Quantitative polymerase chain reaction (QPCR) analysis revealed dominant bacterial groups, aerobic ammonia-oxidizing bacteria (AOB) and anaerobic ammonia oxidizing bacteria (AnAOB), which accounted for 12.99% and 8.32% of total bacteria respectively. As a whole, in the SNAD process, nitrogen and COD are removed from the wastewater simultaneously.Download high-res image (101KB)Download full-size image
Co-reporter:Jianhua Zhang, Qiong Zhang, Xiyao Li, Yuanyuan Miao, Yawen Sun, Miao Zhang, Yongzhen Peng
Bioresource Technology 2017 Volume 243(Volume 243) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.biortech.2017.06.129
•PNSPR granular sludge reactor was rapidly started up in 67 days.•Seeding with DPR sludge was benefit to the achievement of PN and phosphorus removal.•The high phosphorus content in DPR sludge and BPR facilitated rapid granulation.•Provide suitable influent for anammox process when dealing with domestic sewage.Obtaining desirable partial nitritation (PN) is crucial for successful application of the combined PN and anammox process. In this study, the partial nitritation and simultaneously phosphorus removal (PNSPR)1 granular sludge reactor treating low-strength domestic sewage was rapidly started up in 67 days through seeding denitrifying phosphorus removal (DPR)2 sludge. The nitrite/ammonium ratio in effluent was approximately 1 and the nitrite accumulation rate (NAR) was more than 95%, about 93% of orthophosphate was removed. The DPR sludge rich in phosphate accumulating organisms (PAOs) with few nitrifying bacteria could promote the achievement of PNSPR. Quantitative microbial analysis showed that the ammonium oxidizing bacteria (AOB) gene ratio in sludge increased from 0.21% to 3.43%, while nitrite oxidizing bacteria (NOB) gradually decreased to 0.07%. The average particle size of sludge increased from 114 to 421 μm, indicating the formation of PNSPR granules. The high phosphorus content in sludge and phosphorus removal facilitated rapid granulation.Download high-res image (229KB)Download full-size image
Co-reporter:Wenlong Liu, Yongzhen Peng, Bin Ma, Linna Ma, Fangxu Jia, Xiyao Li
Bioresource Technology 2017 Volume 244, Part 1(Volume 244, Part 1) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.biortech.2017.07.131
•Recovery periods of nutrient removal prolonged with the aerobic starvation time.•Nitrite accumulation was achieved by the slower activity recovery of NOB than AOB.•Nitrifiers keep growing during 7 days’ aerobic starvation and then gradually decay.•PHA, glycogen and poly-P were utilized by PAOs to provide energy for maintenance.•Proteobacteria and Bacteroidetes decline while a remarkable increase of Firmicutes.The knowledge of the effect of aerobic starvation on the functional bacterial activities and community structures is important for the recovery of nutrient removal in activated sludge system. Four aerobic starvation processes (3, 7, 14 and 30 days) for nitrifiers and polyphosphate accumulating organisms (PAOs) were studied. The results showed that nitrifiers could utilize the released ammonium for growth during the first 7 days of the aerobic starvation, and then gradually decayed. In the recovery period, the slower recovery ability of nitrite-oxidizing bacteria (NOB) than ammonium-oxidizing bacteria (AOB) contributed to the nitrite accumulation. Besides, the sequential consumption of polyhydroxyalkanoates (PHA), glycogen and the utilization of polyphosphate (poly-P) in PAOs provided the energy to maintain bacterial metabolic activity. High-throughput sequencing analysis revealed that aerobic starvation had substantial impacts on the succession of microbial community, and the majority of original dominant species within the phylum Proteobacteria and Bacteroidetes declined while Firmicutes increased.Download high-res image (99KB)Download full-size image
Co-reporter:Jinjin Liu, Yue Yuan, Baikun Li, Qiong Zhang, Lei Wu, Xiyao Li, Yongzhen Peng
Bioresource Technology 2017 Volume 244, Part 1(Volume 244, Part 1) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.biortech.2017.08.055
•AOA-SBR via sludge fermentation products directly for wastewater was developed.•AOA-SBR realized SND, partial nitrification and sludge reduction.•Total nitrogen and phosphorus removal efficiency reached to 88.8% and 99.3%.•AOA-SBR had simpler operational control.An anaerobic-aerobic-anoxic sequencing batch reactor (AOA-SBR) using sludge fermentation products as carbon source was developed to enhance nitrogen and phosphorus removal in municipal wastewater with low C/N ratio (<4) and reduce sludge production. The AOA-SBR achieved simultaneous partial nitrification and denitrification (SND), aerobic phosphorus uptake and anoxic denitrification through the real-time control and the addition of sludge fermentation products. The average removal efficiencies of total nitrogen (TN), phosphorus (PO43−-P) and chemical oxygen demand (COD) after 145-day operation were 88.8%, 99.3% and 81.2%, respectively. Nitrite accumulation ratio (NAR) reached 99.1% and sludge reduction rate reached 44.1–52.1%. Specifically, 34.4% of the TN removal was carried out by SND and 57.5% by denitrification. Illumina MiSeq sequencing indicated that ammonium-oxidizing bacteria (Nitrosomonas) were enriched and nitrite-oxidizing bacteria (Nitrospira) did not exist in AOA-SBR. The system demonstrated potential to solve the dual problem of insufficient carbon source and sludge reduction.
Co-reporter:Rui Du, Shenbin Cao, Meng Niu, Baikun Li, Shuying Wang, Yongzhen Peng
International Biodeterioration & Biodegradation 2017 Volume 122(Volume 122) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.ibiod.2017.04.018
•Partial-denitrification for nitrite production was established in SBR and USB.•NPR of 0.12–2.21 kgN m−3 d−1 in SBR and 0.80–13.85 kgN m−3 d−1 in USB was obtained.•Nitrite production rate achieved 3.54 and 5.58 g N gVSS−1 d−1 in SBR and USB.•Granulation was observed in SBR and USB with diameter of 1.5–2.0 mm and 2.0–3.0 mm.•The suitability of partial-denitrification effluent for anammox was evaluated.Partial-denitrification (nitrate (NO3−-N) → nitrite (NO2−-N)) holds great potential in treating NO3−-N contained wastewater, by combining with anammox process. In this study, performance of NO2−-N production in partial-denitrification was investigated in two installations: sequencing batch reactor (SBR) and upflow sludge blanket (USB) reactor. Results indicated that partial-denitrification was established successfully in both of SBR and USB, with the NO2−-N production rate (NPR) of 0.13–2.11 kg N m−3 d−1 and 0.90–13.03 kg N m−3 d−1, respectively. The NO3−-N to NO2−-N transformation ratio (NTR) was approximately 83.3% in SBR, while NTR of 51.0%–71.3% was obtained in USB. Sludge granulation was observed in both two reactors during the operation. In SBR, granular diameter of 1.5–2.0 mm was reached with sludge volume index (SVI) of 54.3 mL gSS−1, and 2.0–3.0 mm in USB with SVI of 62.1 mL gSS−1. Additionally, the ratio of COD to NO2−-N (COD/NO2−-N) and NO3−-N to NOX−-N percentage (NP) in partial-denitrification effluent demonstrated its suitability for subsequent anammox. While, partial-denitrification conducted in SBR was more suitable for low NO3−-N wastewater (30 mg L−1), and USB was appropriate for high-strength sewage. Results obtained in this study provide a solid foundation for future applying partial-denitrification combined with anammox process in treating NO3−-N contained wastewater.
Co-reporter:Rui Du, Shenbin Cao, Baikun Li, Meng Niu, Shuying Wang, Yongzhen Peng
Water Research 2017 Volume 108(Volume 108) pp:
Publication Date(Web):1 January 2017
DOI:10.1016/j.watres.2016.10.051
•Two novel DEAMOX were established for simultaneously treating NH4+-N and NO3−-N.•Stable nitrogen removal efficiency of 93.6% was achieved in acetate-driven DEAMOX.•Nitrogen removal efficiency declined from 90.0% to 85.2% in ethanol-driven DEAMOX.•Genera Thauera (61.53% and 45.17%) would play key role in partial-denitrification.•Brocadia and Kuenenia were identified in acetate-SBR, only Kuenenia in ethanol-SBR.In this study, a novel DEAMOX (DEnitrifying AMmonium OXidation) process coupling anammox with partial-denitrification generated nitrite (NO2−-N) from nitrate (NO3−-N) was developed for simultaneously treating ammonia (NH4+-N) and NO3−-N containing wastewaters. The performance was evaluated in sequencing batch reactors (SBRs) with different carbon sources for partial-denitrification: acetate (R1) and ethanol (R2). Long-term operation (180 days) suggested that desirable nitrogen removal was achieved in both reactors. The performance maintained stably in R1 despite the seasonal decrease of temperature (29.2 °C–12.7 °C), and high nitrogen removal efficiency (NRE) of 93.6% on average was obtained with influent NO3−-N to NH4+-N ratio (NO3−-N/NH4+-N) of 1.0. The anammox process contributed above 95% to total nitrogen (TN) removal in R1 with the nitrate-to-nitrite transformation ratio (NTR) of 95.8% in partial-denitrification. A little lower NRE was observed in R2 with temperature dropped from 90.0% at 22.7 °C to 85.2% at 16.6 °C due to the reduced NTR (87.0%–67.0%).High-throughput sequencing analysis revealed that Thauera genera were dominant in both SBRs (accounted for 61.53% in R1 and 45.17% in R2) and possibly played a key role for partial-denitrification with high NO2−-N accumulation. The Denitratisoma capable of complete denitrification (NO3−-N→N2) was found in R2 that might lead to lower NTR. Furthermore, different anammox species was detected with Candidatus Brocadia and Candidatus Kuenenia in R1, and only Candidatus Kuenenia in R2.Download high-res image (317KB)Download full-size image
Co-reporter:Rui Du, Shenbin Cao, Baikun Li, Shuying Wang, Yongzhen Peng
Chemosphere 2017 Volume 174(Volume 174) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.chemosphere.2017.02.013
•DEAMOX was developed to treat domestic wastewater and NO3−-N sewage simultaneously.•TN removal efficiency achieved 95.8% with influent NO3−-N/NH4+-N ratio of 1.09.•Performance recovered rapidly after deterioration for mass transfer limitation.•The dominant Thauera genera possibly played key role in high NO2−-N accumulation.A novel DEAMOX system was developed for nitrogen removal from domestic wastewater and nitrate (NO3−-N) sewage in sequencing batch reactor (SBR). High nitrite (NO2−-N) was produced from NO3−-N reduction in partial-denitrification process, which served as electron acceptor for anammox and was removed with ammonia (NH4+-N) in domestic wastewater simultaneously. A 500-days operation demonstrated that the efficient and stable nitrogen removal performance could be achieved by DEAMOX. The total nitrogen (TN) removal efficiency was as high as 95.8% with influent NH4+-N of 63.58 mg L−1 and NO3−-N of 69.24 mg L−1. The maximum NH4+-N removal efficiency reached up to 94.7%, corresponding to the NO3−-N removal efficiency of 97.8%. The biomass of partial-denitrification and anammox bacteria was observed to be wall-growth. The deteriorated nitrogen removal performance occurred due to excess denitrifying microbial growth in the outer layer of sludge consortium, which prevented the substrate transfer for anammox inside. However, an excellent nitrogen removal could be guaranteed by scrapping the superficial denitrifying biomass at regular intervals. Furthermore, the high-throughput sequencing analysis revealed that the Thauera genera (26.33%) was possibly responsible for the high NO2−-N accumulation in partial-denitrification and Candidatus Brocadia (1.7%) was the major anammox species.Download high-res image (216KB)Download full-size image
Co-reporter:Wei Zeng;Boxiao Li;Yingying Yang;Xiangdong Wang
Bioprocess and Biosystems Engineering 2014 Volume 37( Issue 2) pp:277-287
Publication Date(Web):2014 February
DOI:10.1007/s00449-013-0993-4
Impact of nitrite on aerobic phosphorus (P) uptake of poly-phosphate accumulating organisms (PAOs) in three different enhanced biological phosphorus removal (EBPR) systems was investigated, i.e., the enriched PAOs culture fed with synthetic wastewater, the two lab-scale sequencing batch reactors (SBRs) treating domestic wastewater for nutrient removal through nitrite-pathway nitritation and nitrate-pathway nitrification, respectively. Fluorescence in situ hybridization results showed that PAOs in the three sludges accounted for 72, 7.6 and 6.5 % of bacteria, respectively. In the enriched PAOs culture, at free nitrous acid (FNA) concentration of 0.47 × 10−3 mg HNO2-N/L, aerobic P-uptake and oxidation of intercellular poly-β-hydroxyalkanoates were both inhibited. Denitrifying phosphorus removal under the aerobic conditions was observed, indicating the existence of PAOs using nitrite as electron acceptor in this culture. When the FNA concentration reached 2.25 × 10−3 mg HNO2-N/L, denitrifying phosphorus removal was also inhibited. And the inhibition ceased once nitrite was exhausted. Corresponding to both SBRs treating domestic wastewater with nitritation and nitrification pathway, nitrite inhibition on aerobic P-uptake by PAOs did not occur even though FNA concentration reached 3 × 10−3 and 2.13 × 10−3 mg HNO2-N/L, respectively. Therefore, PAOs taken from different EBPR activated sludges had different tolerance to nitrite.
Co-reporter:Ru-long Zhu;Shu-ying Wang;Jun Li;Kai Wang;Lei Miao;Bin Ma;Ling-xiao Gong;Yong-zhen Peng
Journal of Chemical Technology and Biotechnology 2013 Volume 88( Issue 10) pp:1898-1905
Publication Date(Web):
DOI:10.1002/jctb.4047
Abstract
Background
The post-denitritation sequencing batch reactor (SBR) is widely-used and can achieve high levels of nitrogen removal. In this study the effect of influent COD/TN (total nitrogen) ratio (i.e. C/N ratio) on nitrogen removal performance was investigated.
Results
The experimental results showed that polyhydroxybutyrate (PHB) was the internal carbon source for denitritation, so PHB degradation rate following first-order kinetics was the rate-limiting step both for simultaneous nitritation–denitritation (SND) in the substrate famine period of the oxic stage and endogenous denitritation in the anoxic stage. Higher influent C/N ratio resulted in more PHB fractions in microorganisms, which facilitated a higher efficiency of SND and a faster endogenous denitritation rate (DNR). Consequently, mean TN removal ratio in oxic stage dropped from 32.81% to 8.61%, and average endogenous DNR in the anoxic stage fell from 1.50 to 0.27 mgN h-1 gVSS-1, when influent C/N ratio changed from 6.82 to 1.89. Furthermore, PHB fraction in the biomass did not drop drastically when influent C/N ratio dropped for a short-term period, which facilitated better resistance to shock loads.
Conclusion
High influent C/N ration benefits nitrogen removal in this process, and an influent C/N ratio of 4.00 was suitable for advanced nitrogen removal. © 2013 Society of Chemical Industry
Co-reporter:Shijian Ge;Congcong Lu
Frontiers of Environmental Science & Engineering 2013 Volume 7( Issue 1) pp:135-142
Publication Date(Web):2013 February
DOI:10.1007/s11783-012-0454-3
Based on the anoxic/oxic (A/O) step feed process, a modified University of Cape Town (UCT) step feed process was developed by adding an anaerobic zone and adjusting sludge return pipeline. Performance evaluation of these two types of processes was investigated by optimizing operational parameters, such as the anaerobic/anoxic/oxic volumes, internal recycle ratios, and sludge retention times, for removal of chemical oxygen demanding (COD), nitrogen, and phosphorus. Results showed high removal efficiencies of COD of (85.0±1.7)%, ammonium of (99.7±0.2)%, total nitrogen (TN) of (85.5±1.7)%, phosphorus of (95.1±3.3)%, as well as excellent sludge settleability with average sludge volume index of (83.7±9.5) L·mg−1 in the modified UCT process. Moreover, (61.5±6.0)% of influent COD was efficiently involved in denitrification or phosphorus release process. As much as 35.3% of TN was eliminated through simultaneous nitrification and denitrification process in aerobic zones. In addition, the presence of denitrifying phosphorus accumulating organisms (DNPAOs), accounting for approximately 39.2% of PAOs, was also greatly beneficial to the nitrogen and phosphorus removal. Consequently, the modified UCT step feed process was more attractive for the wastewater treatment plant, because it had extremely competitive advantages such as higher nutrient removal efficiencies, lower energy and dosages consumption, excellent settling sludge and operational assurance.
Co-reporter:Bin Ma;Shuying Wang;Guibing Zhu
Frontiers of Environmental Science & Engineering 2013 Volume 7( Issue 2) pp:267-272
Publication Date(Web):2013 April
DOI:10.1007/s11783-012-0439-2
Denitrifying phosphorus accumulating organisms (DPAOs) using nitrite as an electron acceptor can reduce more energy. However, nitrite has been reported to have an inhibition on denitrifying phosphorus removal. In this study, the step-feed strategy was proposed to achieve low nitrite concentration, which can avoid or relieve nitrite inhibition. The results showed that denitrification rate, phosphorus uptake rate and the ratio of the phosphorus uptaken to nitrite denitrified (anoxic P/N ratio) increased when the nitrite concentration was 15 mg·L−1 after step-feeding nitrite. The maximum denitrification rate and phosphorus uptake rate was 12.73 mg NO2−-N·g MLSS−1·h−1 and 18.75 mg PO43−-P·g MLSS−1·h−1, respectively. These rates were higher than that using nitrate (15 mg·L−1) as an electron acceptor. The maximum anoxic P/N ratio was 1.55 mg PO43− P·mg NO2−-N−1. When the nitrite concentration increased from 15 to 20 mg NO2−-N·L−1 after addition of nitrite, the anoxic phosphorus uptake was inhibited by 64.85%, and the denitrification by DPAOs was inhibited by 61.25%. Denitrification rate by DPAOs decreased gradually when nitrite (about 20 mg ·L−1) was added in the step-feed SBR. These results indicated that the step-feed strategy can be used to achieve denitrifying phosphorus removal using nitrite as an electron acceptor, and nitrite concentration should be maintained at low level (<15 mg·L−1 in this study).
Co-reporter:Jin Guo;Feng Sheng;Jianhua Guo;Xiong Yang
Frontiers of Environmental Science & Engineering 2012 Volume 6( Issue 2) pp:280-287
Publication Date(Web):2012 April
DOI:10.1007/s11783-011-0336-0
Dissolved organic matter (DOM) transformation in sequence batch reactor (SBR) fed with carbon sources of different biodegradability was investigated. During the biologic degradation process, the low molecular weight (MW) fraction (< 1 kDa) gradually decreased, while the refractory compounds with higher aromaticity were aggregated. Size exclusion chromatography (SEC) and fluorescence of excitation emission matrices (EEM) demonstrated that more biopolymers (polysaccharides or proteins) and humic-like substances were presented in the extracellular polymeric substance (EPS) extracted from the SBR fed with sodium acetate or glucose, while the EPS from SBR fed with slowly biodegradable dissolved organic carbon (DOC) substratestarch had relatively less biopolymers. Comparing the EfOM in sewage effluent of three SBRs, the effluent from SBR fed with starch is more aromatic. Organic carbon with MW>1 kDa as well as the hydrophobic fraction in DOM gradually increased with the carbon sources changing from sodium acetate to glucose and starch. The DOC fractionation and the EEM all demonstrated that EfOM from the effluent of the SBR fed with starch contained more fulvic acid-like substances comparing with the SBR fed with sodium acetate and glucose.
Co-reporter:Zhaoxu Peng;Zhenbo Yu
Frontiers of Environmental Science & Engineering 2012 Volume 6( Issue 6) pp:884-891
Publication Date(Web):2012 December
DOI:10.1007/s11783-012-0408-9
Low dissolved oxygen (DO) is an energysaving condition in activated sludge process. To investigate the possible application of limited filamentous bulking (LFB) in sequencing batch reactor (SBR), two lab-scale SBRs were used to treat synthetic domestic wastewater and real municipal wastewater, respectively. The results showed that prolonging low DO aeration duration and setting pre-anoxic (anaerobic) phase were effective strategies to induce and inhibit filamentous sludge bulking, respectively. According to the sludge settleability, LFB could be maintained steadily by adjusting operation patterns. Filamentous bacteria content and sludge volume index (SVI) were likely correlated. SVI fluctuated dramatically within a few cycles when around 200 mL·g−1, where altering operation pattern could change sludge settleability in spite of the unstable status of activated sludge system. Energy consumption by aeration reduced under low DO LFB condition, whereas the nitrification performance deteriorated. However, short-cut nitrification and simultaneous nitrification denitrification (SND) were prone to take place under such conditions. When the cycle time kept constant, the anoxic (anaerobic) to aerobic time ratio was determining factor to the SND efficiency. Similarity keeping aerobic time as constant, the variation trends of SND efficiency and specific SND rate were uniform. SBR is a promising reactor to apply the LFB process in practice.
Co-reporter:Yong-Zhen Peng;Chang-Yong Wu;Ran-Deng Wang;Xiao-Ling Li
Journal of Chemical Technology and Biotechnology 2011 Volume 86( Issue 4) pp:541-546
Publication Date(Web):
DOI:10.1002/jctb.2548
Abstract
BACKGROUND: Nitrite is toxic to anoxic phosphorus uptake when it exceeds a threshold concentration. In this study, denitrifying phosphorus removal with nitrite as electron acceptor was investigated in a sequencing batch reactor (SBR) operated using a real-time step feed strategy.
RESULTS: The nitrite pulse concentration was initially determined by batch experiments. pH increased with use of nitrite for phosphate uptake, and decreased when the nitrite was used up. Nitrite was added promptly after the pH reached the peak value, and phosphate uptake continued, driven by the nitrite addition. The pH was adjusted to 7.50 using HCl with each pulse of nitrite addition. ORP could be used to determine the endpoint of denitrifiying phosphorus removal. However, the variation of second derivative of ORP with time was much more sensitive and should be a more suitable control parameter than ORP itself to determine the endpoint of denitrifying phosphorus removal.
CONCLUSION: Compared with denitrifying phosphorus removal with nitrate as electron acceptor, denitrifying phosphorus removal with nitrite using real-time step feed can save 22.3% of polyhydroxyalkanoate (PHA) for phosphorus removal and 49.4% of PHA for nitrogen removal. In addition, the reaction time could be shortened. Copyright © 2010 Society of Chemical Industry
Co-reporter:Jianhua Wang;Yongzhi Chen
Frontiers of Environmental Science & Engineering 2011 Volume 5( Issue 3) pp:
Publication Date(Web):2011 September
DOI:10.1007/s11783-011-0360-0
A laboratory-scale anaerobic-anoxic-aerobic process (A2O) with a small aerobic zone and a bigger anoxic zone and biologic aerated filter (A2O-BAF) system was operated to treat low carbon-to-nitrogen ratio domestic wastewater. The A2O process was employed mainly for organic matter and phosphorus removal, and for denitrification. The BAF was only used for nitrification which coupled with a settling tank Compared with a conventional A2O process, the suspended activated sludge in this A2O-BAF process contained small quantities of nitrifier, but nitrification overwhelmingly conducted in BAF. So the system successfully avoided the contradiction in sludge retention time (SRT) between nitrifying bacteria and phosphorus accumulating organisms (PAOs). Denitrifying phosphorus accumulating organisms (DPAOs) played an important role in removing up to 91% of phosphorus along with nitrogen, which indicated that the suspended activated sludge process presented a good denitrifying phosphorus removal performance. The average removal efficiency of chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), and NH4+-N were 85.56%, 92.07%, 81.24% and 98.7% respectively. The effluent quality consistently satisfied the national first level A effluent discharge standard of China. The average sludge volume index (SVI) was 85.4 mL·g−1 additionally, the volume ratio of anaerobic, anoxic and aerobic zone in A2O process was also investigated, and the results demonstrated that the optimum value was 1:6:2.
Co-reporter:Zhirong Sun, Hui Ge, Xiang Hu, Yongzhen Peng
Separation and Purification Technology 2010 Volume 72(Issue 2) pp:133-139
Publication Date(Web):20 April 2010
DOI:10.1016/j.seppur.2010.01.014
Electrochemically reductive dechlorination of 2,4-dichlorophenol in aqueous solution was investigated on palladium/polymeric pyrrole film/foam-nickel (Pd/PPy/foam-Ni) electrode at ambient temperature. Pd/PPy/foam-Ni electrode, which provided catalytic surface for reductive dechlorination of 2,4-dichlorophenol, was prepared with an electrodepositing method. Cyclic voltammetry (CV) tests reveal that the hydrogen adsorption peak current on Pd/PPy/foam-Ni electrode was −150.4 mA. Scanning electron microscope (SEM) images show that PPy film modified the electrode surface characteristics. The dechlorination experimental results indicate that 2,4-dichlorophenol removal efficiency of 99.4% and current efficiency of 33.6% on Pd/PPy/foam-Ni electrode could be obtained under the conditions of dechlorination current of 5 mA and dechlorination time of 70 min in aqueous solution. The analysis of HPLC identifies that the final products were mainly phenol.
Co-reporter:Changyong Wu;Xiaoling Li
Frontiers of Environmental Science & Engineering 2010 Volume 4( Issue 2) pp:150-156
Publication Date(Web):2010 June
DOI:10.1007/s11783-010-0020-9
In this study, an anaerobic/anoxic/oxic (A2O) wastewater treatment process was implemented to treat domestic wastewater with short-term atrazine addition. The results provided an evaluation on the effects of an accidental pollution on the operation of a wastewater treatment plant (WWTP) in relation to Chemical Oxygen Demand (COD) and biological nutrient removal. Domestic wastewater with atrazine addition in 3 continuous days was treated when steady biological nutrient removal was achieved in the A2O process. The concentrations of atrazine were 15, 10, and 5 mg·L−1 on days 1, 2 and 3, respectively. The results showed that atrazine addition did not affect the removal of COD. The specific NH4+ oxidation rate and NO3− reduction rate decreased slightly due to the short-term atrazine addition. However, it did not affect the nitrogen removal due to the high nitrification and denitrification capacity of the system. Total nitrogen (TN) removal was steady, and more than 70% was removed during the period studied. The phosphorus removal rate was not affected by the short-term addition of atrazine under the applied experimental conditions. However, more poly-hydroxy-alkanoate (PHA) was generated and utilized during atrazine addition. The results of the oxygen uptake rate (OUR) showed that the respiration of nitrifiers decreased significantly, while the activity of carbon utilizers had no obvious change with the atrazine addition. Atrazine was not removed with the A2O process, even via absorption by the activated sludge in the process of the short-term addition of atrazine.
Co-reporter:Qing Yang, Xiuhong Liu, Chengyao Peng, Shuying Wang, Hongwei Sun and Yongzhen Peng
Environmental Science & Technology 2009 Volume 43(Issue 24) pp:9400-9406
Publication Date(Web):November 12, 2009
DOI:10.1021/es9019113
Nitrite has been commonly recognized as an important factor causing N2O production, which weakened the advantages of nitrogen removal via nitrite. To reduce and control N2O production from wastewater treatment plants, both long-term and batch tests were carried out to investigate main sources and pathways of N2O production during nitrogen removal via nitrite from real domestic wastewater. The obtained results showed that N2O production during nitrogen removal via nitrite was 1.5 times as much as that during nitrogen removal via nitrate. It was further demonstrated that ammonia oxidization were main source of N2O production during nitrogen removal from domestic wastewater; whereas, almost no N2O was produced during nitrite oxidization and anoxic denitrification. N2O production during nitrogen removal via nitrite decreased about 50% by applying the step-feed SBR, due to the effective control of nitrite and ammonia, the precursors of N2O production. Therefore, the step-feed system is recommended as an effective method to reduce N2O production during nitrogen removal via nitrite from domestic wastewater.
Co-reporter:Z. Sun;H. Ge;X. Hu;Y. Peng
Chemical Engineering & Technology 2009 Volume 32( Issue 1) pp:134-139
Publication Date(Web):
DOI:10.1002/ceat.200800313
Abstract
Electrochemical dechlorination of chloroform in aqueous solution was investigated on a palladium-loaded meshed titanium electrode at ambient temperature. The palladium/titanium (Pd/Ti) electrode, which provided a catalytic surface for reductive dechlorination of chloroform in aqueous solution, was prepared with an electrodepositing method. Scanning electron microscope (SEM) micrographs show that Pd microparticles uniformly disperse on the meshed Ti electrode with spheroidal structure. Dechlorination experimental results indicate that, in aqueous solution with the high current efficiency of 33 %, the removal efficiency of chloroform on the Pd/Ti electrode was 37 %, under the conditions of a dechlorination current of 0.1 mA and dechlorination time of 180 min.
Co-reporter:Chen-hong Zhao;Yong-zhen Peng;Shu-ying Wang;Akio Takigawa
Journal of Chemical Technology and Biotechnology 2008 Volume 83( Issue 12) pp:1587-1595
Publication Date(Web):
DOI:10.1002/jctb.1943
Abstract
BACKGROUND: UniFed SBR is a novel process that can achieve high levels of nitrogen and phosphorus removal simultaneously in a simple single SBR tank. In this study, effects of influent C/N ratio, influent C/P ratio and volumetric exchange ratio on biological phosphorus removal in UniFed SBR process were investigated in a lab-scale UniFed apparatus treating real domestic wastewater.
RESULTS: The results showed that phosphorus removal efficiency increased as C/N ratio increased from 27% at 2.8 to 88% at 5.7. For C/N ratios 6.5 and above, complete phosphorus removal could be achieved. When C/N ratios and volumetric exchange ratio were fixed at 6 and 33%, respectively, phosphorus removal efficiency remained at 100% for C/P ratios higher than 33; effluent phosphate concentration was below the detection limit. For C/P ratios lower than 33, phosphorus removal efficiency decreased linearly with C/P ratio. Under the same influent C/N ratio and C/P ratio, the following factors all contributed to better phosphorus removal performance: greater volumetric exchange ratio; more organic substrate for PAOs to utilize, less inhibition by NOx− of phosphorus release during the feed/decant period; more PHB synthesized; and more aerobic phosphate uptake.
CONCLUSION: High influent C/N ratio, high C/P ratio and high volumetric exchange ratio were beneficial to phosphorus removal in this process. Copyright © 2008 Society of Chemical Industry
Co-reporter:W. Zeng;Y.-Z. Peng;S.-Y. Wang;C.-Y. Peng
Chemical Engineering & Technology 2008 Volume 31( Issue 4) pp:582-587
Publication Date(Web):
DOI:10.1002/ceat.200700468
Abstract
Nitrogen removal via nitrite is a novel technology and is becoming popular for engineering applications since it results in a saving of the aeration energy required for nitritation and external carbon sources for denitritation. An alternating aerobic-anoxic (AAA) operational pattern was applied in a sequencing batch reactor (SBR) process to improve the nitrogen removal efficiency and achieve partial nitrification via nitrite from industrial wastewater with influent alkalinity deficiencies. The results showed that the online monitoring of the pH-time variations during nitrification could indicate if the alkalinity was sufficient and when the ammonia nitrogen was completely oxidized. Under conditions of deficient influent alkalinity, the AAA process reduced the external alkalinity and the carbon sources addition and improved the effluent quality with ammonia nitrogen concentration below the detection limits. Half of the alkalinity previously consumed during aerobic nitrification could be recovered during the subsequent anoxic denitrification period. If the cycles of alternating aerobic/anoxic were repeated more than twice, the first nitrification cycle was stopped when the pH decreased by 0.4–0.5. The middle nitrification was terminated when the pH decreased by 0.8–1.0, and the final nitrification duration was controlled by the dissolved oxygen (DO) breakpoint and ammonia valley on the pH profile. Each anoxic time-scale for denitrification was determined by the nitrate knee on the oxidation-reduction potential (ORP) profile and the nitrate apex on the pH profiles. In comparison to the conventional SBR process, the AAA process with a real-time control strategy resulted in an improved nitrogen removal efficiency of greater than 97 % under conditions of deficient influent alkalinity. Moreover, nitrogen removal via nitrite was achieved with a nitrite accumulation rate above 95 %.
Co-reporter:Xuelei Wu;Lunqiang Chen
Frontiers of Environmental Science & Engineering 2008 Volume 2( Issue 2) pp:
Publication Date(Web):2008 June
DOI:10.1007/s11783-008-0008-x
The effect of dissolved oxygen (DO) concentration on nitrite accumulation was investigated in a pilot-scale pre-denitrification process at room temperature for 100 days. In the first 10 days, due to the instability of the system, the DO concentration fluctuated between 1.0 and 2.0 mg/L. In the next 14 days, the DO concentration was kept at 0.5 mg/L and nitrite accumulation occurred, with the average nitrite accumulation rate at 91%. From the 25th day, the DO concentration was increased to 2.0 mg/L to destroy the nitrite accumulation, but nitrite accumulation rate was still as high as 90%. From the 38th day the nitrite accumulation rate decreased to 15%–30% linearly. From the 50th day, DO concentration was decreased to 0.5 mg/L to resume nitrite accumulation. Until the 83rd day the nitrite accumulation rate began to increase to 80%. Dissolved oxygen was the main cause of nitrite accumulation, taking into account other factors such as pH, free ammonia concentration, temperature, and sludge retention time. Because of the different affinity for oxygen between nitrite oxidizing bacteria and ammonia oxidizing bacteria when DO concentration was kept at 0.5 mg/L, nitrite accumulation occurred.
Co-reporter:Jun Li;Yongjiong Ni
Frontiers of Environmental Science & Engineering 2008 Volume 2( Issue 1) pp:99-102
Publication Date(Web):2008 March
DOI:10.1007/s11783-008-0017-9
The objectives of this study were to establish an on-line controlling system for nitrogen and phosphorus removal synchronously of municipal wastewater in a sequencing batch reactor (SBR). The SBR for municipal wastewater treatment was operated in sequences: filling, anaerobic, oxic, anoxic, oxic, settling and discharge. The reactor was equipped with on-line monitoring sensors for dissolved oxygen (DO), oxidation-reduction potential (ORP) and pH. The variation of DO, ORP and pH is relevant to each phase of biological process for nitrogen and phosphorus removal in this SBR. The characteristic points of DO, ORP and pH can be used to judge and control the stages of process that include: phosphate release by the turning points of ORP and pH; nitrification by the ammonia valley of pH and ammonia elbows of DO and ORP; denitrification by the nitrate knee of ORP and nitrate apex of pH; phosphate uptake by the turning point of pH; and residual organic carbon oxidation by the carbon elbows of DO and ORP. The controlling system can operate automatically for nitrogen and phosphorus efficiently removal.
Co-reporter:Qing Yang, Yongzhen Peng, Xiuhong Liu, Wei Zeng, Takashi Mino and Hiroyasu Satoh
Environmental Science & Technology 2007 Volume 41(Issue 23) pp:8159-8164
Publication Date(Web):November 3, 2007
DOI:10.1021/es070850f
Although many studies regarding nitrogen removal via nitrite have been carried out, very limited research has been undertaken on nitrogen removal via nitrite at low temperatures. In this study, to improve the nitrogen removal efficiency from municipal wastewater, a pilot-plant of sequencing batch reactor with a working volume of 54 m3 was used to investigate nitrogen removal via nitrite from municipal wastewater at normal and low water temperature. The obtained results showed that high nitrogen removal efficiency with effluent total nitrogen below 3 mg/L could be achieved. Using real-time control with temperature ranging from 11.9 to 26.5 °C under normal dissolved oxygen condition (≥2.5 mg/L), nitrogen removal via nitrite was successfully and stably achieved for a long period (180 days) with average nitrite accumulation rate above 95%. Fluorescence in situ hybridization was carried out to investigate the quantitative changes of nitrifying microbial community in the activated sludge. Fluorescence in situ hybridization results approved that the nitrifying microbial communities were optimized; ammonia oxidizing bacteria became the dominant nitrifying bacteria and nitrite oxidizing bacteria had been washed out of the activated sludge.
Co-reporter:X. L. Wang;Y. Z. Peng;Y. Ma;S. Y. Wang
Chemical Engineering & Technology 2007 Volume 30(Issue 2) pp:
Publication Date(Web):25 JAN 2007
DOI:10.1002/ceat.200600076
The aim of this work is to study the effects of six operational variables, i.e., dissolved oxygen (DO), nitrate recirculation flow, sludge recycle flow, sludge wastage flow, external carbon dosage, and anoxic volume fraction, on the performance of nitrogen removal and its control in a pre-denitrification plant. The results obtained show that the six operational variables have a significant influence on nitrogen removal in such a system, while the utilization of the control strategies can improve the situation to a significant extent. The control of DO concentration should be correlated with the influent ammonia load, the effluent requirement and nitrification type. The anoxic effluent nitrate concentration should be controlled at ca. 2 mg/L or the ORP value at the end of the anoxic zone should be controlled at ca. –90 mV. The control of the sludge recycling flow by online monitoring of the sludge blanket height (SBH), is an alternative to the conventional control of the constant sludge recycle flow. It may be possible to achieve the automatic control of sludge wastage flow by online measuring of the ammonia concentration and the nitrification capacity of the sludge. The recirculation of nitrate and external carbon dosage should be simultaneously controlled to optimize nitrogen removal. The anoxic volume fraction should also be optimized, to ensure a good balance between nitrification and denitrification.
Co-reporter:Xiaolian Wang;Yong Ma
Bioprocess and Biosystems Engineering 2007 Volume 30( Issue 2) pp:91-97
Publication Date(Web):2007 March
DOI:10.1007/s00449-006-0104-x
The feasibility of nitrite accumulation in a pilot-scale A/O (anoxic/oxic) nitrogen removal plant treating domestic wastewater was investigated at various dissolved oxygen (DO) concentrations and pH levels. The results showed that the pH was not a useful operational parameter to realize nitrite accumulation. Significant nitrite accumulation was observed at the low DO concentration range of 0.3–0.8 mg/l and the maximum nitrite accumulation ratio of about 90% occurred at a DO concentration of 0.6 mg/l. This suggests a reduction of 22% in the oxygen consumption, and therefore a considerable saving in aeration. However, the nitrite accumulation was destroyed at the high DO concentration and the resumption was very slow. In addition, the average ammonia removal efficiency reached as high as 93% at the low DO level. Moreover, experimental results indicated that nitrogen could be removed by simultaneous nitrification and denitrification (SND) via nitrite in the aerobic zones at the low DO concentration, with the efficiency of 6–12%.
Co-reporter:Jun Li;Guowei Gu;Su Wei
Frontiers of Environmental Science & Engineering 2007 Volume 1( Issue 2) pp:246-250
Publication Date(Web):2007 May
DOI:10.1007/s11783-007-0042-0
An aerobic sequencing batch biofilm reactor (SBBR) packed with Bauer rings was used to treat real domestic wastewater for simultaneous nitrification and denitrification. The SBBR is advantageous for creating an anoxic condition, and the biofilm can absorb and store carbon for good nitrification and denitrification. An average concentration of oxygen ranging from 0.8 to 4.0 mg/L was proved very efficient for nitrification and denitrification. Volumetric loads of TN dropped dramatically and effluent TN concentration increased quickly when the concentration of average dissolved oxygen was more than 4.0 mg/L. The efficiency of simultaneous nitrification and denitrification (SND) increased with increasing thickness of the biofilm. The influent concentration hardly affected the TN removal efficiency, but the effluent TN increased with increasing influent concentration. It is suggested that a subsequence for denitrification be added or influent amount be decreased to meet effluent quality requirements. At optimum operating parameters, the TN removal efficiency of 74%–82% could be achieved.
Co-reporter:Qing Yang;Anming Yang
Frontiers of Environmental Science & Engineering 2007 Volume 1( Issue 4) pp:488-492
Publication Date(Web):2007 October
DOI:10.1007/s11783-007-0078-1
The feasibility of pH and oxidation reduction potential (ORP) as on-line control parameters to advance nitrogen removal in pulsed sequencing batch reactors (SBR) was evaluated. The pulsed SBR, a novel operational mode of SBR, was utilized to treat real municipal wastewater accompanied with adding ethanol as external carbon source. It was observed that the bending-point (apex and knee) of pH and ORP profiles can be used to control denitrification process at a low influent C/N ratio while dpH/dt can be used to control the nitrification and denitrification process at a high influent C/N ratio. The experimental results demonstrated that the effluent total nitrogen can be reduced to lower than 2 mg/L, and the average total nitrogen (TN) removal efficiency was higher than 98% by using real-time controll strategy.
Co-reporter:Wei Zeng;Shuying Wang
Frontiers of Environmental Science & Engineering 2007 Volume 1( Issue 1) pp:28-32
Publication Date(Web):2007 February
DOI:10.1007/s11783-007-0005-5
In order to improve the nitrogen removal efficiency and save operational cost, the feasibility of the alternating aerobic-anoxic process (AAA process) applied in a sequencing batch reactor (SBR) system for nitrogen removal was investigated. Under sufficient influent alkalinity, the AAA process did not have an advantage over one aerobicanoxic (OAA) cycle on treatment efficiency because microorganisms had an adaptive stage at the alternating aerobic-anoxic transition, which would prolong the total cycling time. On the contrary, the AAA process made the system control more complicated. Under deficient influent alkalinity, when compared to OAA, the AAA process improved treatment efficiency and effluent quality with NH4+-N in the effluent below the detection limit. In the nitrification, the average stoichiometric ratio between alkalinity consumption and ammonia oxidation is calculated to be 7.07 mg CaCO3/mg NH4+-N. In the denitrification, the average stoichiometric ratio between alkalinity production and NO3−-N reduction is about 3.57 mg CaCO3/mg NO3−-N. As a result, half of the alkalinity previously consumed during the aerobic nitrification was recovered during the subsequent anoxic denitrification period. That was why the higher treatment efficiency in the AAA process was achieved without the supplement of bicarbonate alkalinity. If the lack of alkalinity in the influent was less than 1/3 of that needed, there is no need for external alkalinity addition and treatment efficiency was the same as that under sufficient influent alkalinity. Even if the lack of alkalinity in the influent was more than 1/3 of that needed, the AAA process was an optimal strategy because it reduced the external alkalinity addition and saved on operational cost.
Co-reporter:Yong Ma;Shuying Wang
Journal of Chemical Technology and Biotechnology 2006 Volume 81(Issue 1) pp:41-47
Publication Date(Web):18 OCT 2005
DOI:10.1002/jctb.1355
Dynamic modelling and simulation is increasingly being employed as an aid in the design and operation of wastewater treatment plants (WWTPs). In this paper a simulation model is used to investigate the control of an activated sludge process. Two different control strategies to optimise nitrogen removal in a predenitrification process are presented, which are based on the control of the sludge blanket height (SBH) or sludge age (sludge retention time, SRT) and mixed liquor suspended solids (MLSS) in the reactor, by adjusting the sludge wastage and sludge recycle flow rates, respectively. It is shown how the recycle and wastage flow rate variables can be employed to continually maintain plant operation in the presence of disturbances. The performance of the control strategies has been assessed by the COST 624 benchmark plant and a pilot plant. The results have shown the robustness of the implementation and the efficiency of the proposed control strategies, which have been operated automatically in a safe, stable and optimum operating point, improving effluent quality and reducing energy costs. Consideration is also given as to how plant operation could be optimised in the long-term in order to meet the yearly total nitrogen standard. Copyright © 2005 Society of Chemical Industry
Co-reporter:Miao Zhang, Qing Yang, Jianhua Zhang, Cong Wang, ... Yongzhen Peng
Journal of Bioscience and Bioengineering (October 2016) Volume 122(Issue 4) pp:456-466
Publication Date(Web):1 October 2016
DOI:10.1016/j.jbiosc.2016.03.019
A two-sludge system consisting of anaerobic anoxic oxic–biological contact oxidation (A2/O–BCO) was developed to treat domestic wastewater with a low carbon/nitrogen (COD/TN) ratio (around 3.21) by shortening sludge retention time (SRT) for phosphorus accumulating organisms (PAOs) in the A2/O reactor and prolonging SRT for nitrifiers in the BCO reactor. Specifically, the BCO reactor was composed of three stages in series (N1, N2 and N3), so that simultaneous nitrogen and phosphorus removals by denitrifying PAOs (DNPAOs) was achieved in the A2/O reactor with NOx−–N as the electron acceptor from the BCO reactor. Long term operational tests (600 days) were conducted with various operational parameters [e.g., hydraulic retention time (HRTs), nitrate recycling ratio (Rs), volume ratio (Vs)] to examine the denitrifying phosphorus removal performance. The system exhibited the highest removal of TN and PO43−–P at the HRTs of 8 h, Rs of 300% and Vs of 2:4:1. The optimal TN and PO43−–P removals were 80.30% and 96.61% at low COD/TN of 3.21. The species diversity and microbial community examined by the Illumina MiSeq method demonstrated the fact of two-sludge system, and the improved community structure by long-term optimization was prominent comparing with the seed sludge. Additionally, Accumulibacter and Dechloromonas were the dominant functional PAOs with 25.74% in the A2/O reactor, while nitrifiers (including Nitrosomonas and Nitrospira) were gradually enriched with 13.10%, 21.33%, and 31.10% in the three stages of the BCO reactor.
Co-reporter:Jianlong WANG, Yongzhen PENG, Shuying WANG, Yongqing GAO
Chinese Journal of Chemical Engineering (October 2008) Volume 16(Issue 5) pp:778-784
Publication Date(Web):1 October 2008
DOI:10.1016/S1004-9541(08)60155-X
Sequence hybrid biological reactor (SHBR) was proposed, and some key control parameters were investigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification (SND) via nitrite. SND via nitrite was achieved in SHBR by controlling demand oxygen (DO) concentration. There was a programmed decrease of the DO from 2.50 mg·L−1 to 0.30 mg·L−1, and the average nitrite accumulation rate (NAR) was increased from 16.5% to 95.5% in 3 weeks. Subsequently, further increase in DO concentration to 1.50 mg·L−1 did not destroy the partial nitrification to nitrite. The results showed that limited air flow rate to cause oxygen deficiency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate. Nitrogen removal efficiency was increased with the increase in NAR, that is, NAR was increased from 60% to 90%, and total nitrogen removal efficiency was increased from 68% to 85%. The SHBR could tolerate high organic loading rate (OLR), COD and ammonia-nitrogen removal efficiency were greater than 92% and 93.5%, respectively, and it even operated under low DO concentration (0.5 mg·L−1) and maintained high OLR (4.0 kg COD·m−3·d−1). The presence of biofilm positively affected the activated sludge settling capability, and sludge volume index (SVI) of activated sludge in SHBR never hit more than 90 ml·g−1 throughout the experiments.
Co-reporter:Yuanyuan Miao, Liang Zhang, Baikun Li, Qian Zhang, Simeng Wang, Yongzhen Peng
Bioresource Technology (May 2017) Volume 231() pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.biortech.2017.01.045
•AOB played a main role in SPN/A nitrogen performance.•Anammox bacterial activity increased with AOB activity despite high NOB activity.•Combining intermittent aeration and bio-augmentation enhanced SPN/A stabilization.Intermittent aeration and bio-augmentation were integrated to enhance single-stage partial nitrification-anammox (SPN/A) stability over 235-day operational period treating low-strength sewage. The effect of bio-augmentation sludge (with different abundances of ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB)) was determined. Partial nitrification sludge based bio-augmentation increased the total nitrogen (TN) removal efficiency from 29.1% to 70%, followed by the nitrification sludge (from 38.1% to 65.4%), then the denitrifying phosphorus sludge (from 42.1% to 54.4%). The evolution of bacteria activity and communities showed that anammox activity increased with the enhancement of AOB activity, and higher AOB abundance led to higher anammox bacterial abundance despite high NOB abundance. The enhancement of AOB activity produced more nitrite, anammox bacteria gained more nitrite than NOB since intermittent aeration selectively inhibited NOB, thus the reactor stability enhanced substantially. This study highlights the significance of enhancing AOB activity to ensure long-term operational stability of SPN/A processes.Download high-res image (195KB)Download full-size image
Co-reporter:Xiyao Li, Yongzhen Peng, Yuelan He, Shuying Wang, Siyu Guo, Lukai Li
Bioresource Technology (March 2017) Volume 227() pp:
Publication Date(Web):1 March 2017
DOI:10.1016/j.biortech.2016.12.069
•The optimum SRT for the stabilization of WAS should be higher than 10.7 d.•Effects of temperature on SCOD release were greater at SRT of 32 d and 6.4 d.•CST was not correlated with soluble proteins/soluble carbohydrates in supernatant.•CST was observed to be the minimum at SRT of 10.7 d both in MT-AD and RT-AD.Anaerobic treatment is the most widely used method of waste activated sludge (WAS) stabilization. Using a semi-continuous stirring tank with condensed WAS, we investigated effects of decreasing the solid retention time (SRT) from 32 days to 6.4 days on sludge reduction, soluble chemical oxygen demand (SCOD) release and dehydration capability, along with anaerobic digestion operated at medium temperature (MT-AD) or anaerobic digestion operated at room temperature (RT-AD). Results showed that effects of temperature on SCOD release were greater at SRT of 32 d and 6.4 d. When SRT was less than 8 d, total solids (TS), volatile solids (VS) and capillary suction time (CST) did not change significantly. CST was lowest at SRT of 10.7 days, indicating best condition for sludge dehydration. Principal component analysis (PCA) showed that the most optimum SRT was higher than 10.7 d both in MT-AD or RT-AD.
Co-reporter:Gaoqiang Su, Shuying Wang, Zhiguo Yuan, Yongzhen Peng
Journal of Bioscience and Bioengineering (March 2016) Volume 121(Issue 3) pp:293-298
Publication Date(Web):1 March 2016
DOI:10.1016/j.jbiosc.2015.07.009
Volatile fatty acids (VFAs) are essential for removing biological nitrogen and phosphorus in wastewater treatment plants. The purpose of this work was to investigate whether and how the addition of NaCl could improve the production of VFAs from waste activated sludge (WAS). Sludge solubilization was efficiently improved by the addition of NaCl. Both protein and carbohydrate in the fermentation liquid increased with the dosage of NaCl, and it provided a larger amount of organic compounds for the production of the VFAs. NaCl had inhibitory effects on the production of methane and a high dosage of NaCl could severely suppress the growth of methanogens, which decreased the consumption of the VFAs. Consequently, the production of VFAs was significantly enhanced by the addition of NaCl. The maximum production of VFAs was achieved with the highest dosage of NaCl (3316 mg (COD)/L at the NaCl dosage 0.5 mol/L; 783 mg (COD)/L without the addition of NaCl). Therefore, this study indicates that using NaCl could be an efficient method for improving the production of VFAs from WAS.
Co-reporter:Yong-zhen PENG, Yong MA, Shu-ying WANG
Journal of Environmental Sciences (March 2007) Volume 19(Issue 3) pp:284-289
Publication Date(Web):1 March 2007
DOI:10.1016/S1001-0742(07)60046-1
The aim of this study is to investigate the denitrification potential enhancement by addition of external carbon sources and to estimate the denitrification potential for the predenitrification system using nitrate utilization rate (NUR) batch tests. It is shown that the denitrification potential can be substantially increased with the addition of three external carbon sources, i.e. methanol, ethanol, and acetate, and the denitrification rates of ethanol, acetate, and methanol reached up to 9.6, 12, and 3.2 mgN/(g VSS·h), respectively, while that of starch wastewater was only 0.74 mgN/(g VSS·h). By comparison, ethanol was found to be the best external carbon source. NUR batch tests with starch wastewater and waste ethanol were carried out. The denitrification potential increased from 5.6 to 16.5 mg NO3-N/L owing to waste ethanol addition. By means of NUR tests, the wastewater characteristics and kinetic parameters can be estimated, which are used to determine the denitrification potential of wastewater, to calculate the denitrification potential of the plant and to predict the nitrate effluent quality, as well as provide information for developing carbon dosage control strategy.
Co-reporter:Changyong WU, Yongzhen PENG, Shuying WANG, Xiaoling LI, Randeng WANG
Chinese Journal of Chemical Engineering (June 2011) Volume 19(Issue 3) pp:512-517
Publication Date(Web):1 June 2011
DOI:10.1016/S1004-9541(11)60014-1
In this study, four sequencing batch reactors (SBR), with the sludge retention time (SRT) of 5, 10, 20 and 40 d, were used to treat domestic wastewater, and the effect of SRT on nitrite accumulation in the biological nitrogen removal SBR was investigated. The real-time control strategy based on online parameters, such as pH, dissolved oxygen (DO) and oxidation reduction potential (ORP), was used to regulate the nitrite accumulation in SBR. The model-based simulation and experimental results showed that with the increase of SRT, longer time was needed to achieve high level of nitritation. In addition, the nitrite accumulation rate (NAR) was higher when the SRT was relatively shorter during a 112-day operation. When the SRT was 5 d, the system was unstable with the mixed liquor suspended solids (MLSS) decreased day after day. When the SRT was 40 d, the nitrification process was significantly inhibited. SRT of 10 to 20 d was more suitable in this study. The real-time control strategy combined with SRT control in SBR is an effective method for biological nitrogen removal via nitrite from wastewater.
Co-reporter:Lina Wu, Yongzhen Peng, Xiao Shi, Chengyao Peng, Jie Zhang
Chinese Journal of Chemical Engineering (July 2015) Volume 23(Issue 7) pp:1225-1230
Publication Date(Web):1 July 2015
DOI:10.1016/j.cjche.2015.05.014
A system consisting of a two-stage up-flow anaerobic sludge blanket (UASB) reactor and an anoxic/aerobic (A/O) reactor was used to treat municipal landfill leachate. Denitrification took place in the first stage of the UASB reactor (UASB1). The chemical oxygen demand of the UASB1 effluent was further decreased in the second stage (UASB2). Nitrification was accomplished in the A/O reactor. When diluted with tap water at a ratio of 1:1, the ammonia nitrogen concentration of the influent leachate was approximately 1200 mg·L− 1, whereas that of the system effluent was approximately 8–11 mg·L− 1, and the corresponding removal efficiency is about 99.08%. Stable partial nitrification was achieved in the A/O reactor with 88.61%–91.58% of the nitrite accumulation ratio, even at comparatively low temperature (16 °C). The results demonstrate that free ammonia (FA) concentrations within a suitable range exhibit a positive effect on partial nitrification. In this experiment when FA was within the 1–30 mg·L− 1 range, partial nitrification could be achieved, whereas when FA exceeded 280 mg·L− 1, the nitrification process was entirely inhibited. Temperature was not the key factor leading to partial nitrification within the 16–29 °C range. The inhibitory influence of free nitrous acid (FNA) on nitrification was also minimal when pH was greater than 8.5. Thus, FA concentration was a major factor in achieving partial nitrification.A system comprising a two-stage up-flow anaerobic sludge blanket (UASB) reactor and an anoxic–aerobic (A/O) reactor was used to treat landfill leachate in the experiment. Part of the recycled effluent as well as the influent of the system was pumped into the first-stage UASB reactor (UASB1). The organic compounds in the raw landfill leachate were depleted through serving as the carbon source for denitrification of the recycled effluent in UASB1, while simultaneously, methanogenesis occurred. Some organic compounds in the UASB1 effluent were also depleted via methanogenesis in UASB2. Recycled sludge from the clarifying tank was then pumped into the anoxic zone, the first chamber of the A/O reactor, in which denitrification of NOx−-N (nitrite and nitrate nitrogen) took place. Nitrification of ammonia occurred in the aerobic zone of the A/O reactor. A diagram of the process is presented in Fig. 1. As a result, stable partial nitrification was obtained with 93% nitrite accumulation in the A/O reactor and 99% nitrogen removal efficiency even at low temperature in the whole system which was fully dependent on biological treatment in treating leachate. And these were little reported by other researchers.Download full-size image
Co-reporter:Yue Yuan, Jinjin Liu, Bin Ma, Ye Liu, Bo Wang, Yongzhen Peng
Bioresource Technology (December 2016) Volume 222() pp:
Publication Date(Web):1 December 2016
DOI:10.1016/j.biortech.2016.09.103
•Sludge fermentation products were added to F-SBR to improve wastewater nutrients removal.•Corresponding total nitrogen and PO43−-P removal efficiency was 82.9% and 96.0%.•NO2−-N accumulation and denitrifying phosphorus removal via nitrite occurred.•The waste activated sludge was reduced by 862.1 mg VSS/d in 10 L F-SBR.This study presents a novel strategy to improve the removal efficiency of nitrogen and phosphorus from municipal wastewater by feeding sequencing batch reactor (SBR) with sludge alkaline fermentation products as carbon sources. The performances of two SBRs treating municipal wastewater (one was fed with sludge fermentation products; F-SBR, and the other without sludge fermentation products; B-SBR) were compared. The removal efficiencies of total nitrogen (TN) and phosphorus (PO43−-P) were found to be 82.9% and 96.0% in F-SBR, while the corresponding values in B-SBR were 55.9% (TN) and −6.1% (PO43−-P). Illumina MiSeq sequencing indicated that ammonium-oxidizing bacteria (Nitrosomonadaceae and Nitrosomonas) and denitrifying polyphosphate accumulating organisms (Dechloromonas) were enriched in F-SBR, which resulted in NO2−-N accumulation and denitrifying phosphorus removal via nitrite (DPRN). Moreover, feeding of sludge fermentation products reduced 862.1 mg VSS/d of sludge in the F-SBR system (volume: 10 L).Download high-res image (101KB)Download full-size image
Co-reporter:Shenbin Cao, Rui Du, Meng Niu, Baikun Li, Nanqi Ren, Yongzhen Peng
Bioresource Technology (December 2016) Volume 221() pp:
Publication Date(Web):1 December 2016
DOI:10.1016/j.biortech.2016.08.082
•A novel ANAMMOX-PD process was successful applied for advanced nitrogen removal.•The effluent NO3−-N was below 20 mg/L with NRE of 97.3% under influent TN of 840 mg/L.•Domestic wastewater was treated simultaneously with NRE of 96.7%.•Partial denitrification was achieved stably with NTR approximately 80%.•Microbial community in ANAMMOX reactor was analyzed via high-throughput sequencing.In this study, a novel integrated anaerobic ammonium oxidization with partial denitrification process (termed as ANAMMOX-PD) was developed for advanced nitrogen removal from high-strength wastewater, which excess NO3−-N produced by ANAMMOX was fed into PD reactor for NO2−-N production and then refluxing to ANAMMOX reactor for further removal. Results showed that total nitrogen (TN) removal efficiency as high as 97.8% was achieved and effluent TN-N was below 20 mg/L at influent TN-N of 820 mg/L. Furthermore, the feasibility of simultaneously treating domestic wastewater was demonstrated in ANAMMOX-PD process, and NH4+-N removal efficiency of 96.7% was obtained. The nitrogen removal was mainly carried out through ANAMMOX pathway, and high-throughput sequencing revealed that Candidatus_Brocadia was the major ANAMMOX species. The presented process could effectively solve the problem of excess nitrate residual in ANAMMOX effluent, which hold a great potential in application of currently ANAMMOX treating high-strength wastewater (e.g. sludge digestion supernatant).Download high-res image (250KB)Download full-size image
Co-reporter:Bo Wang, Yongzhen Peng, Yuanyuan Guo, Shuying Wang
Journal of Bioscience and Bioengineering (April 2016) Volume 121(Issue 4) pp:431-434
Publication Date(Web):1 April 2016
DOI:10.1016/j.jbiosc.2015.08.007
Waste activated sludge (WAS) fermentation integrated with denitritation (the reduction of nitrite to dinitrogen gas) at different pHs was investigated in batch-mode reactors over a 24-day period. The results showed that in comparison with controlled pHs, the volatile fatty acid (VFA) bioproduction for in situ denitritation was significantly improved at uncontrolled pH. VFA fermented from WAS was quickly consumed by denitritation at uncontrolled pH, which accelerated sludge degradation. On the other hand, sludge digestion was benefited from the alkalinity produced from denitritation, while methanogenesis was prohibited by alkalinity and nitrite. The integrated sludge fermentation and denitritation can be cost-effectively applied to wastewater treatment plants, so that organic substrates (e.g., VFAs) are produced for denitritation via simultaneous sludge fermentation, which enables WAS reutilization and enhances nitrogen removal efficiency without the need of external carbon sources.
Co-reporter:Jianhua Guo, Shuying Wang, Zhongwei Wang, Yongzhen Peng
Journal of Water Process Engineering (April 2014) Volume 1() pp:108-114
Publication Date(Web):1 April 2014
DOI:10.1016/j.jwpe.2014.03.011
Understanding of the competition between floc-formers and filaments is critical to prevent filamentous bulking in practice. This study aimed to investigate the effects of feeding pattern and dissolved oxygen (DO) concentration on their competition in four sequencing batch reactors (SBRs). Short feeding under anoxic condition (fill time < 10 min) resulted in a well-settling sludge (sludge volume index (SVI) < 100 mL/g), in spite of DO concentrations. Sludge settleability deteriorated (SVI > 200 mL/g) and filamentous bulking was observed when the substrate was added in a limiting rate by prolonging the anoxic fill time up to 90 min. In contrast, sludge settleability in fully aerobic systems was quite poor (SVI > 500 mL/g) in spite of the feeding length. Compared to the systems with an anoxic fill phase, more types and abundant filamentous bacteria were identified in fully aerobic systems. Microscopic observation, staining reactions and fluorescence in situ hybridization analysis indicated that the extensive filaments, including Thiothrix nivea, Type 021N, Type 1851 and Microthrix parvicella, proliferated in fully aerobic systems. The results of this study indicated that substrate gradients played an important role on the competition between filaments and floc-formers. It is recommend the adoption of plug-flow selector configurations, with anoxic conditions in order to maintain good and robust sludge settleability.
Co-reporter:Mu Liu, Qing Yang, Yongzhen Peng, Tiantian Liu, ... Shuying Wang
Journal of Industrial and Engineering Chemistry (25 December 2015) Volume 32() pp:63-71
Publication Date(Web):25 December 2015
DOI:10.1016/j.jiec.2015.07.017
•Saline landfill leachate was treated using UASB combine with A/O by SBNR.•The characteristics of N2O emission under different salinity were elucidated.•The N2O conversion ratio to the influent removed NH4+-N increased by 14.7 times.•The COD entering the A/O was increased and thus stimulated N2O emission remarkably during the aerobic zone.•The increase of Nitrosomonas europaea was an important factor for the increase of N2O emission.Landfill leachate was treated using the upflow anaerobic sludge blanket (UASB) combined with anoxic/aerobic reactor (A/O) for shortcut biological nitrogen removal. The treatment performance and nitrous oxide (N2O) emission were studied under different salinity. When salinity increased from 10 to 35 g/L, the removal efficiency of ammonium nitrogen and total nitrogen decreased from 99.3 to 83.9% and from 85.4 to 68.4%, respectively while the nitrite accumulation rate always remained high at more than 94.3%. The N2O conversion ratio increased by 14.7 times, from 0.3 to 4.7%. The concentration of biodegradable COD in influent of the A/O reactor increased with the increase of salinity, which lead to the decrease of dissolved oxygen and thus stimulated N2O emission remarkably during the aerobic zone. Meanwhile, the N2O emissions were likely to occur by a combination of pathways since the simultaneous nitritation and denitritation was occurred in aerobic zone. The increase of NH4+-N concentration, NO2−-N concentration and pH caused by high salinity also promoted the N2O emission. The population of Nitrosomonas europaea increased with salinity, which was important for N2O emission.
Co-reporter:Zhaoxu PENG, Yongzhen PENG, Lijuan GUI, Xuliang LIU
Chinese Journal of Chemical Engineering (2010) Volume 18(Issue 3) pp:472-477
Publication Date(Web):1 January 2010
DOI:10.1016/S1004-9541(10)60245-5
In order to investigate the competition for carbon source between denitrification and phosphorus release processes, simultaneous phosphorus release and denitrification in sludge operated in anoxic, aerobic mode are investigated by varying the ratio of influent COD to nitrogenous compound concentration under anoxic condition using a lab-scale sequencing batch reactor (SBR). The results show that the nitrate reduction rate is nearly independent of the ratio of influent COD to nitrate under anoxic condition. More NO−x -N in the influent leads to less PO3−4 -P release during the feeding period. However, PO3−4 -P release proceeds at a low rate simultaneously with denitrification even when the influent NO−x -N concentration is as large as 20 mg·L−1 and its rate is increased obviously when NO−x -N is denitrified to a concentration lower than 0.5 mg·L−1. The variation of pH during anoxic period gives some information about the biochemical reactions of denitrification and PO3−4 -P release. When more nitrate is present in the influent, more acetate uptake in feeding period is used for direct microorganism growth.
Co-reporter:Zhirong SUN, Baohua LI, Xiang HU, Min SHI, ... Yongzhen PENG
Journal of Environmental Sciences (2008) Volume 20(Issue 3) pp:268-272
Publication Date(Web):1 January 2008
DOI:10.1016/S1001-0742(08)60042-X
Electrochemical dechlorination of chloroform in neutral aqueous solution was investigated using palladium-loaded electrodes at ambient temperature. Palladium/foam-nickel (Pd/foam-Ni) and palladium/polymeric pyrrole film/foam-nickel (Pd/PPy/foam-Ni) composite electrodes which provided catalytic surface for reductive dechlorination of chloroform in aqueous solution were prepared using an electrodepositing method. Scanning electron microscope (SEM) micrographs showed that polymeric pyrrole film modified the electrode-surface characteristics and resulted in the uniform dispersion of needle-shaped palladium particles on foam-Ni supporting electrode. The experimental results of dechlorination indicated that the removal efficiency of chloroform and current efficiency in neutral aqueous solution on Pd/PPy/foam-Ni electrode could be up to 36.8% and 33.0% at dechlorination current of 0.1 mA and dechlorination time of 180 min, which is much higher than that of Pd/foam-Ni electrode.
Co-reporter:Yongzhen PENG, Hongxun HOU, Shuying WANG, Youwei CUI, Yuan Zhiguo
Journal of Environmental Sciences (2008) Volume 20(Issue 4) pp:398-403
Publication Date(Web):1 January 2008
DOI:10.1016/S1001-0742(08)62070-7
To achieve high efficiency of nitrogen and phosphorus removal and to investigate the rule of simultaneous nitrification and denitrification phosphorus removal (SNDPR), a whole course of SNDPR damage and recovery was studied in a pilot-scale, anaerobic- anoxic oxidation ditch (OD), where the volumes of anaerobic zone, anoxic zone, and ditches zone of the OD system were 7, 21, and 280 L, respectively. The reactor was fed with municipal wastewater with a flow rate of 336 L/d. The concept of simultaneous nitrification and denitrification (SND) rate (rSND) was put forward to quantify SND. The results indicate that: (1) high nitrogen and phosphorus removal efficiencies were achieved during the stable SND phase, total nitrogen (TN) and total phosphate (TP) removal rates were 80% and 85%, respectively; (2) when the system was aerated excessively, the stability of SND was damaged, and rSND dropped from 80% to 20% or less; (3) the natural logarithm of the ratio of NOx to NH4+ in the effluent had a linear correlation to oxidation-reduction potential (ORP); (4) when NO3− was less than 6 mg/L, high phosphorus removal efficiency could be achieved; (5) denitrifying phosphorus removal (DNPR) could take place in the anaerobic-anoxic OD system. The major innovation was that the SND rate was devised and quantified.
Co-reporter:Xiuhong LIU, Yi PENG, Changyong WU, Takigawa AKIO, Yongzhen PENG
Journal of Environmental Sciences (2008) Volume 20(Issue 6) pp:641-645
Publication Date(Web):1 January 2008
DOI:10.1016/S1001-0742(08)62106-3
The production of N20 during nitrogen removal from real domestic wastewater was investigated in a lab-scale aerobic-anoxic sequencing batch reactor with a working volume of 14 L. The results showed that the total N20-N production reached higher than 1.87 mg/L, and up to 4% of removed nitrogen was converted into N20. In addition, N20 led to a much higher greenhouse effect than C02 during aerobic reaction phase, this proved that N20 production could not be neglected. The N2ON production during nitrification was 1.85 mg/L, whereas, during denitrification, no N20 was produced, nitrification was the main source of N20 production during nitrogen removal. Furthermore, during denitrification, the dissolved N20 at the end of aeration was found to be further reduced to N2. Denitrification thus had the potential of controlling N20 production.
Co-reporter:Gui-bing ZHU, Yong-zhen PENG, Shu-yun WU, Shu-ying WANG, Shi-wei XU
Journal of Environmental Sciences (2007) Volume 19(Issue 9) pp:1043-1048
Publication Date(Web):1 January 2007
DOI:10.1016/S1001-0742(07)60170-3
The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates. Biological occurrence of simultaneous nitrification and denitrification was verified in the aspect of nitrogen mass balance and alkalinity. The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate. In each experimental run the floe sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floe.
Co-reporter:Shu-jun ZHANG, Yong-zhen PENG, Shu-ying WANG, Shu-wen ZHENG, Jin GUO
Journal of Environmental Sciences (2007) Volume 19(Issue 6) pp:647-651
Publication Date(Web):1 January 2007
DOI:10.1016/S1001-0742(07)60108-9
An UASB+Anoxic/Oxic (A/O) system was introduced to treat a mature landfill leachate with low carbon-to-nitrogen ratio and high ammonia concentration. To make the best use of the biodegradable COD in the leachate, the denitrification of NOx−-N in the recirculation effluent from the clarifier was carried out in the UASB. The results showed that most biodegradable organic matters were removed by the denitrification in the UASB. The NH4+-N loading rate (ALR) of A/O reactor and operational temperature was 0.28–0.60 kg NH4+-N/(m3·d) and 17–29°C during experimental period, respectively. The short-cut nitrification with nitrite accumulation efficiency of 90%–99% was stabilized during the whole experiment. The NH4+-N removal efficiency varied between 90% and 100%. When ALR was less than 0.45 kg NH4+-N/(m3·d), the NH4+-N removal efficiency was more than 98%. With the influent NH4+-N of 1200–1800 mg/L, the effluent NH4+-N was less than 15 mg/L. The shortcut nitrification and denitrification can save 40% carbon source, with a highly efficient denitrification taking place in the UASB. When the ratio of the feed COD to feed NH4+-N was only 2–3, the total inorganic nitrogen (TIN) removal efficiency attained 67%–80%. Besides, the sludge samples from A/O reactor were analyzed using FISH. The FISH analysis revealed that ammonia oxidation bacteria (AOB) accounted for 4% of the total eubacterial population, whereas nitrite oxidation bacteria (NOB) accounted only for 0.2% of the total eubacterial population.
Co-reporter:Miao Zhang, Yongzhen Peng, Cong Wang, Chuanxin Wang, Weihua Zhao, Wei Zeng
Biochemical Engineering Journal (15 February 2016) Volume 106() pp:26-36
Publication Date(Web):15 February 2016
DOI:10.1016/j.bej.2015.10.027
•A novel two-sludge AAO-BCO was developed for wastewater with low COD/TN ratio.•HRT affected PHA utilization and denitrification capacity (NO3−-N/PO43−-P ratio).•AAO-BCO saved 30–35% carbon sources compared with traditional processes.•Sufficient NO3−-N load and longer anoxic duration improved the activities of DNPAOs at different HRTs.A modified two-sludge system consisting of AAO and BCO (Anaerobic anoxic oxic-biological contact oxidation) was developed. The unique advantage was the high efficient utilization of influent carbon sources in AAO reactor with NO3−-N produced in BCO reactor, which achieved the simultaneous removal of both nitrogen and phosphorus. With real municipal wastewater at low carbon/nitrogen ratio (COD/TN = 3.50), the influence of hydraulic retention time (HRT = 6 –12 h) in the AAO reactor on denitrifying phosphorus removal was observed. The mass balance analysis demonstrated that the system saved about 30–35% carbon sources compared with traditional biological nutrient removal (BNR) systems. HRT of 10 h was found to be optimal for denitrifying phosphorous removal due to the limitation of poly-β-hydroxyalkanoates (PHA) utilization and denitrification capacity (NO3−-N/PO43−-P ratio). It was also determined that the NO3−-N concentration of the middle settler should be kept around 1.50–2.50 mg/L to prevent secondary phosphorus release. Finally, anoxic duration and NO3−-N loading were the major limiting factors for denitrifying phosphorus accumulation organisms (DNPAOs) growth.
![Ferrate(2-), [7,12-diethenyl-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(4-)-κN21,κN22,κN23,κN24]-, hydrogen (1:2), (SP-4-2)-](/data/chemimg/522800/14875-96-8.png)
![Ferrate(2-), [7,12-diethenyl-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(4-)-κN21,κN22,κN23,κN24]-, hydrogen (1:2), (SP-4-2)-](/data/chemimg/522800/14875-96-8_b.png)
![N-[2,2,2-trichloro-1-(pyrimidin-2-ylamino)ethyl]furan-2-carboxamide](http://img.cochemist.com/ccimg/5600/5556-48-9.png)
![N-[2,2,2-trichloro-1-(pyrimidin-2-ylamino)ethyl]furan-2-carboxamide](http://img.cochemist.com/ccimg/5600/5556-48-9_b.png)
