Biofilms in the pipe wall may lead to water quality deterioration and biological instability in drinking water distribution systems (DWDSs). In this study, bacterial community radial-spatial distribution in biofilms along the pipe wall in a chlorinated DWDS of East China was investigated. Three pipes of large diameter (300, 600, and 600 mm) were sampled in this DWDS, including a ductile cast iron pipe (DCIP) with pipe age of 11 years and two gray cast iron pipes (GCIP) with pipe ages of 17 and 19 years, and biofilms in the upper, middle, and lower parts of each pipe wall were collected. Real-time quantitative polymerase chain reaction (qPCR) and culture-based method were used to quantify bacteria. 454 pyrosequencing was used for bacterial community analysis. The results showed that the biofilm density and total solid (TS) and volatile solid (VS) contents increased gradually from the top to the bottom along the pipe wall. Microorganisms were concentrated in the upper and lower parts of the pipe wall, together accounting for more than 80 % of the total biomass in the biofilms. The bacterial communities in biofilms were significantly different in different areas of the pipe wall and had no strong interaction. Compared with the upper and lower parts of the pipe wall, the bacterial community in the middle of the pipe wall was distributed evenly and had the highest diversity. The 16S rRNA genes of various possible pathogens, including Escherichia coli, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Salmonella enterica, were detected in the biofilms, and the abundances of these possible pathogens were highest in the middle of the pipe wall among three areas. The detachment of the biofilms is the main reason for the deterioration of the water quality in DWDSs. The results of this study suggest that the biofilms in the middle of the pipe wall have highly potential risk for drinking water safety, which provides new ideas for the study of the microbial ecology in DWDS.

•Short- and long-term effects of mineral nutrients on the n-damo were investigated.•High levels of KHCO3 inhibited the n-damo process in short- and long-term tests.•1% CO2 in gas can finely control the pH near neutral in the improved medium.A novel biological nitrogen removal process can be developed based on the newly discovered nitrite-dependent anaerobic methane oxidation (n-damo) process. In this work, the short- and long-term effects of mineral nutrients on the n-damo process were investigated by single-factor and orthogonal experiments, respectively. The pH buffering capacities of different media were determined by acid–base titration. KHCO3 and KH2PO4 greatly influenced the activity of n-damo bacteria and the pH changes of the media. An improved n-damo medium was proposed, containing 0.3 g L−1 CaCl2, 0.2 g L−1 MgSO4, 0.3 g L−1 KH2PO4 and 0.2 g L−1 KHCO3. Moreover, the presence of 1% of CO2 in gas could maintain the pH near neutral in the improved medium, which was first estimated in theory and then verified in practice. Finally, these results were applied in an n-damo reactor. The nitrogen removal rate was slightly increased (from 10.0 ± 1.2 to 10.8 ± 1.4 mg N L−1 d−1), and the pH was quite stable after the improvement (daily changes from 0.58 ± 0.05 to 0.11 ± 0.02).

Nitrite-dependent anaerobic methane oxidation (n-damo) process was reported to be mediated by “Candidatus Methylomirabilis oxyfera”, which belongs to the candidate phylum NC10. M. oxyfera-like bacteria have been detected in lake ecosystems, while their distribution, diversity and abundance in river ecosystems have not been well studied. In this study, both the 16S rRNA and the pmoA molecular biomarkers confirmed the presence of diverse NC10 phylum bacteria related to M. oxyfera in a river ecosystem—the Qiantang River, Zhejiang Province (China). Phylogenetic analysis of 16S rRNA genes demonstrated that the recovered M. oxyfera-like sequences could be grouped into several distinct clusters that exhibited 89.8 % to 98.9 % identity to the M. oxyfera 16S rRNA gene. Similarly, several different clusters of pmoA gene sequences were observed, and these clusters displayed 85.1–95.4 % sequence identity to the pmoA gene of M. oxyfera. Quantitative PCR showed that the abundance of M. oxyfera-like bacteria varied from 1.32 ± 0.16 × 106 to 1.03 ± 0.12 × 107 copies g (dry weight)−1. Correlation analysis demonstrated that the total inorganic nitrogen content, the ammonium content and the organic content of the sediment were important factors affecting the distribution of M. oxyfera-like bacterial groups in the examined sediments. This study demonstrated the distribution of diverse M. oxyfera-like bacteria and their correlation with environmental factors in Qiantang River sediments.

Sulfide-containing waste streams are generated by a number of industries. It is emitted into the environment as dissolved sulfide (S2− and HS−) in wastewaters and as H2S in waste gases. Due to its corrosive nature, biological hydrogen sulfide removal processes are being investigated to overcome the chemical and disposal costs associated with existing chemically based removal processes. The nitrogen and sulfur metabolism interacts at various levels of the wastewater treatment process. Hence, the sulfur cycle offers possibilities to integrate nitrogen removal in the treatment process, which needs to be further optimized by appropriate design of the reactor configuration, optimization of performance parameters, retention of biomass and optimization of biomass growth. The present paper reviews the biotechnological advances to remove sulfides from various environments.

AbstractWorldwide extensive use of plasticized plastics has resulted in phthalates pollution in different environment. Nitrates from industry and agriculture are also widely disseminated in the soils, natural waters and wastewaters. Dimethyl phthalate (DMP) biodegradation by activated sludge cultures under nitrate-reducing conditions was investigated. Under one optimized condition, DMP was biodegraded from 102.20 mg/L to undetectable level in 56 h under anoxic conditions and its reaction fitted well with the first-order kinetics. Using the high-performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC-MS) analysis, mono-methyl phthalate (MMP) and phthalic acid (PA) were detected as the major intermediates of DMP biodegradation. When combined with the determination of chemical oxygen demand (CODCr) removal capacity and pH, DMP was found to be mineralized completely under anoxic conditions. The biodegradation pathway was proposed as DMP → MMP → PA → … → CO2 + H2O. The molar ratio of DMP to nitrate consumed was found to be 9.0:1, which agrees well with the theoretical stoichiometric values of DMP biodegradation by nitrate-reducing bacteria. The results of the non-linear simulation showed that the optimum pH and temperature for the degradation were 7.56 and 31.4°C, respectively.