Thermophilic bacteria pretreated sludge has drawn more interest for hydrogen production, which was more economical (needs less energy), pollution-free (adding a reagent is not needed), and efficient than physico-chemistry pretreated sludge. Comparative studies between thermophilic bacteria (Bacillus sp. AT07-1) and 65 °C heat pretreated sewage sludge have been conducted for hydrogen production. It was concluded that using thermophilic bacteria pretreated sludge for hydrogen production (batch of TB) would produce the highest hydrogen yield of 16.3 mL/g of volatile solid (VS), and it increased by 12.9, 26.4, and 52.3% compared to T + HB (65 °C heat pretreated sludge inoculated with Enterococcus sp. LG1), T (65 °C heat pretreated sludge), and TB + HB (thermophilic bacteria pretreated sludge inoculated with Enterococcus sp. LG1), respectively. The lag time of TB was only 3 h. The hydrogen concentration in the gas phase of TB + HB and T + HB was 66.2 and 67%, respectively, higher than that of TB and T. These results demonstrated that different pretreatments and inoculations could influence the solubilization of sludge, the hydrogen yield, and the hydrogen concentration.

To investigate the chief reason for phosphorus uptake by microorganisms affected by substrates in sequencing batch reactors with the single-stage oxic process, two typical substrates, glucose (R1) and acetate (R2) were used as the sole carbon source, and the performances of phosphorus removal and the changes of intracellular storage were compared. The experimental results showed that the phenomenon of excess phosphorus uptake was observed in two reactors, but bacteria’s capability to take in phosphorus and its intracellular storage were obviously different under the same operational condition. After steady-state operation, total phosphorus (TP) removed per MLVSS in R1 and R2 was 6.7–7.4 and 2.7–3.2 mg/g, respectively. The energy storage of poly-β-hydroxyalkanoates (PHA) was nearly constant in R1 during the whole period, and another aerobic storage of glycogen was accumulated (the max accumulation of glycogen was 3.21 mmol-C/g) when external substrate was consumed, and then was decreased to the initial level. However in R2, PHA and glycogen were both accumulated (2.1 and 0.55 mmol-C/g, respectively) when external substrate was consumed, but they showed different changes after the period of external consumption. Compared to rapid decrease of PHA to the initial level, glycogen continued accumulating to the peak (0.88 mmol-C/g) in 2 h of aeration before decreasing. During the aeration, the accumulations/transformations of internal carbon sources in R1 were higher than those in R2. In addition, obvious TP releases were both observed in R1 and R2 other than PHA and glycogen during the long-term idle period; moreover, the release content of phosphorus in R1 was also higher than that in R2. The researches indicated that different aerobic metabolism of substrate occurred in R1 and R2 due to the different carbon sources in influent, resulting in different types and contents of aerobic storage accumulated/translated in bacteria of R1 and R2. As a result, ATP content provided for phosphorus uptake was different in R1 and R2, and the capability to take up phosphorus was also different from each other.

A sequencing batch reactor (SBR) seeded with methanogenic granular sludge was started up to enrich Anammox (Anaerobic Ammonium Oxidation) bacteria and to investigate the feasibility of granulation of Anammox biomass. Research results showed that hydraulic retention time (HRT) was an important factor to enrich Anammox bacteria. When the HRT was controlled at 30 days during the initial cultivation, the SBR reactor presented Anammox activity at t = 58 days. Simultaneously, the methanogenic granular sludge changed gradually from dust black to brown colour and its diameter became smaller. At t = 90 days, the Anammox activity was further improved. NH4+-N and NO2−N were removed simultaneously with higher speed and the maximum removal rates reached 14.6 g NH4+-N /(m3reactor·day) and 6.67 g NO2−-N /(m3reactor·day), respectively. Between t = 110 days and t = 161 days, the nitrogen load was increased to a HRT of 5 days (70 mg/l NH4+ and 70 mg/l NO2), the removal rates of ammonium and nitrite were 60.6% and 62.5% respectively. The sludge changed to red and formed Anammox granulation with high nitrogen removal activity.

The present lab-scale research reveals the enrichment of anaerobic ammonium oxidation microorganism from methanogenic anaerobic granular sludge and the effect of inorganic carbon (sodium bicarbonate) on anaerobic ammonium oxidation. The enrichment of anammox bacteria was carried out in a 7.0-L sequencing batch reactor (SBR) and the effect of bicarbonate on anammox was conducted in a 3.0-L SBR. Research results, especially the biomass, showed first signs of anammox activity after 54 d cultivation with synthetic wastewater, when the pH was controlled between 7.5 and 8.3, the temperature was 35°C. The anammox activity increased as the influent bicarbonate concentration increased from 1.0 to 1.5 g/L, and then, was inhibited as the bicarbonate concentration approached 2.0 g/L. However, the activity could be restored by the reduction of bicarbonate concentration to 1.0 g/L, as shown by rapid conversion of ammonium, and nitrite and nitrate production with normal stoichiometry. The optimization of the bicarbonate concentration in the reactor could increase the anammox rate up to 66.4 mgN/(L·d).