[Reduction of Wastewater Organic Micro-pollutants and Genotoxicity in a Hybrid Process Involving Anaerobic-anoxic-oxic and Ozonation Treatments].

In recent years, researchers have drawn greater attention to the occurrence, fate, and risk of organic micro-pollutants (OMPs) in the environment. Effluent from municipal wastewater treatment plants (WWTPs) are an important source for the release of OMPs into aquatic environment and should be monitored and controlled. The migration and transformation of 14 selected OMPs and their reduction of genotoxicity after treatment by a hybrid process of anaerobic-anoxic-oxic (AAO) and ozonation were investigated. Results showed that the activated sludge process was poor in removing most OMPs, with removal rates of less than 50%. However, ozonation improved OMPs removal, and the hybrid process could reduce most of the OMPs by more than 90%-with OMPs containing phenolic, aniline, and anisole groups in their aromatic structures showing particular vulnerability to attack by ozone. The results of genotoxicity analyses showed that the wastewater influent and secondary effluent exhibited genotoxicity to an extent, and ozonation reduced the genotoxicity of secondary effluent by 98%, thus largely reducing the environmental risk posed by OMPs in WWTP effluent.

[Removal of Chlortetracycline and Morphological Changes in Heavy Metals in Swine Manure Using the Composting Process].

The widespread use of antibiotics and heavy metals in livestock farms results in large residues of antibiotics and heavy metals in the livestock manure. Composting technology can biodegrade residual antibiotics and solidify heavy metals. A pilot composting reactor was used to analyze the characteristics of chlortetracycline (CTC) removal at different antibiotic concentrations[0 mg·kg-1 (CK), 10 mg·kg-1 (T1), and 50 mg·kg-1 (T2)]. Moreover, the morphological changes in heavy metals during the composting process were analyzed. After composting, no chlortetracycline was detected in the CK group and the antibiotics degradation rates of T1 and T2 groups reached 96.31% and 97.32%, respectively. The chlortetracycline degradation fits the pseudo-first-order kinetics model. Heavy metals can be solidified during the composting; thus, the bioavailable state of Cu and Zn (exchangeable state, reducible state) changed into the oxidation state and residues with apparent passivation formed. The correlation analysis showed that the removal of CTC showed strong positive correlations with the biological available Cu and Zn.

[Influence of substrate concentration on PHA production using fermented sugar cane as substrate].

PHA was a kind of biodegradable polymer produced by mixed microorganisms. In recent years, 3-stage PHA synthesis process (including substrate hydrolysis, culture selection, and PHA synthesis) was commonly used for PHA production. In this kind of process, culture selection is the key stage, which directly affects the PHA production efficiency. In order to deal with sludge bulking occurred in the culture selection system, this paper analyzes the influence of substrate concentration on culture selection efficiency as well as operation stability. Under different influent substrate concentrations of 560 mg x L(-1), 1 120 mg x L(-1) and 1 680 mg x L(-1), we confirmed that influent substrate concentration (COD) of 1 120 mg x L(-1) is the most suitable parameter for the bacteria enriching process after a long period of time under short SRT. After 94 days of cultivation, we achieved 50% of PHA content, 0.7145 COD/COD of PHA conversion rate and 0.191 2 mg x (mg x h)(-1) of specific PHA storage rate at the end of batch tests with nutrient starvation. The study also confirmed that glycogen level in cells has a close relationship with its PHA synthesis ability, which shows its potential to predict the enrichment efficiency.

[Effect of polymeric aluminum-iron on EPS and bio-flocculation in A2/O system].

Polymeric aluminum-iron (PAFC) was added at the end of aeration tank to enhance phosphorus removal, so that the phosphorus concentration in the effluent could meet the calss A standard in municipal sewage treatment plant pollutant discharge standard (GB 18918-2002). The characteristics of extracellular polymer substances (EPS) and bio-flocculation for the activated sludge in the A2/O system were analyzed in the experiment. The results showed that, the gross of EPS varied little with the increase in PAFC dosage, while, the ratio of albumen to polysaccharide declined from 3.30 to 2.30. When the PAFC dosage increased, the concentration of Al3+ in EPS increased during the whole anaerobic-anoxic-aerobic cycle. The flocs of activated sludge became larger after PAFC addition, Zeta potential of the effluent dropped significantly from - 15.83 mV to -21.20 mV and sludge yield increased. Therefore, bio-flocculation of the activated sludge in the A2/O system improved when a proper amount of PAFC was added, subsequently improve the water quality of the effluent.

[Isolation of a PHA producing strain with butyric acid as the carbon source and its shaking-flask fermentation character].

A bacterial strain,WD-3,with high polyhydroxyalkanoates (PHA) yield was isolated from activated sludge. Its fermentation characters including the effects of C:N ratio, pH,fermentation time on the PHA production were also primary studied. The results showed that the optimal C/N ratio and pH were 35 and 7.0, respectively. PHA accumulation increased rapidly during the stable growth stage. The maximum PHA yield was 3.01 g x L(-), the strain accumulated PHA up to 45.4% of its cellular dry weight, and the proportion of PHV occupied one-third of the PHA production. Analysis of its 16S rRNA sequence showed that strain WD-3 belongs to Enterobacter.

[Enhanced ammonia removal and microbial community structure analysis using bacterial quinone profile in ITFB].

Water quality during the start-up period was changed in order to enhance the later nitrifying ability of the internal-circulation three-phase bio-fluidized bed (ITFB). The experimental results showed that high N/C ratio and low feeding concentration of COD were two key conditions for enhancing the ammonia removal. After the enhanced start-up, an efficient removal efficiency of both COD and ammonia was achieved with HRT 2h when treating sanitary wastewater, the average ammonia removal rate was 74% , the ammonia concentration in effluent was lower than 10 mg/L. Bacterial quinone profile of the system was also analyzed. The results showed that after the enhanced start-up, the number of nitrifying bacteria, such as Nitrosomonas europaea, in the biofilm in ITFB was increased, and the number of gamma-Proteobacteria, such as Acinetobacter sp. and Pseudomonas sp., was decreased. the equitability of the quinones (EQ) fluctuated around 0.5 showed that the distribution of the microbial community in the biofilm changed little. UQ/MK ratio of all the samples was greater than 1 indicated that Gram-negative bacteria was the dominant bacteria in the system.