[Effects of Wastewater Discharge on Antibiotic Resistance Genes and Microbial Community in a Coastal Area].

Wastewater treatment plants (WWTPs) are important sources of antibiotic resistance genes (ARGs) in aquatic environments. Mobile genetic elements (MGEs) and microbial communities are key factors that affect the proliferation of ARGs. To reveal the effects of WWTPs effluent discharge on the ARGs and microbial community in a coastal area, the structure and distribution of ARGs, MGEs, and microbial community in Shangyu (SY) and Jiaxing (JX) effluent receiving areas (ERAs) and the offshore area of Hangzhou Bay (HB) were investigated via high-throughput quantitative PCR and 16S rRNA high-throughput sequencing. The results showed that multidrug resistance genes were the most abundant ARGs across all the sampling sites. The diversity and abundance of ARGs and MGEs in the ERAs were much higher than those in the HB. Additionally, the diversities of the microbial community in the JX-ERA were higher than those in the SY-ERA and HB. PCoA showed that the distribution of ARGs, MGEs, and microbial communities in the ERAs and HB were significantly different, indicating that the long-term wastewater discharge could alter the distribution of ARGs, MGEs, and microbial communities in the coastal area. The co-occurrence pattern among ARGs, MGEs, and microbial communities revealed that 12 bacterial genera, such as Psychrobacter, Pseudomonas, Sulfitobacter, Pseudoalteromonas, and Bacillus, showed strong positive correlations with ARGs and MGEs. Most potential hosts carried multidrug and ß-lactamase resistance genes.

[Distribution Characteristics of Antibiotic Resistance Genes in Wastewater Treatment Plants].

Wastewater treatment plants (WWTPs) are regarded as the main source for antibiotic resistant genes (ARGs). To explore the features regarding the distribution of ARGs in wastewater with complicated composition in treatment plants, wastewater samples from a chemical industry park that produced antibiotics were selected. qPCR was applied to detect the type and abundance of ARGs in the wastewater flows from the WWTPs. The results indicated that 16 types of ARGs were detected from the wastewater from the WWTPs, among which sulfonamide resistance genes and tetracycline resistance genes were the dominant ARGs that appeared in the wastewater. Additionally, intI 1 was detected and its abundance was correlated with that of sulfonamide resistance genes. This indicated that intI 1 may promote the migration and transformation of sulfonamide resistance genes. The pharmaceutical factories in the park mainly synthesize macrolide antibiotics. Because of the selective pressure, the absolute abundance of ermB in the wastewater was much higher than that in the other industrial wastewater. The total ARGs decreased by 1.16 log via traditional biological treatment process, and the total ARGs decreased by 2.46 log via the Fenton process. The results showed that the removal effects of deep treatment processes on ARGs were better than that of biological treatment in this wastewater treatment process. Highly abundant and movable ARGs already exist in the water body, and their release from WWTPs without effective treatment poses high risks to the environment.

[Distribution and Removal of Antibiotic Resistance Genes in Two Sequential Wastewater Treatment Plants].

Wastewater treatment plants (WWTPs) have been regarded as important point-sources of antibiotic resistance genes (ARGs) in aquatic environments. To investigate the distribution and removal of ARGs in WWTPs, a pharmaceutical wastewater treatment plant (PWWTP) and an integrated wastewater treatment plant (IWWTP) in a fine-chemical industrial park were chosen, and polymerase chain reaction (PCR) and real-time PCR techniques were used to determine the occurrence and abundances of ARGs along the treatment processes. Ten and fifteen ARGs were detected initially in the influents of PWWTP and IWWTP respectively, in which tetracycline and sulfonamide resistance genes were frequently reported, while dfrA13 was first reported in WWTPs. The most abundant ARGs in the influents were sul Ⅰ and sul Ⅱ, followed by dfrA13, tetQ, floR, tetO, and tetW. The total ARGs increased by 0.21 log after the treatment by PWWTP, whose effluent contributed 0.87% to the inflow yet 5.05% to the total ARGs of IWWTP. Finally the total ARGs removed by IWWTP was 1.03 log, with the remaining ARGs then transported within the final effluent to the nearby coastal area. The authors concluded that the environmental and other impacts from the spread of ARGs on the microbial communities of the coastal environment needed further study.

[Relationship between sewage treatment efficiency and bacterial community diversity in an A/O MBR].

An Anoxic/Oxic Membrane Bioreactor (A/O MBR) was used to treat sewage. Five different working conditions were run to determine the optimal process parameters. Bacterial community structures in both anoxic and oxic tanks were analyzed using denaturing gradient gel electrophoresis (DGGE). The relationship between effluent water quality and bacterial community diversity was established. The experimental results indicated that, under the optimal parameters of hydraulic retention time (HRT) 12 h, sludge retention time (SRT) 10 d, reflux ratio of nitrified effluent 300%, and reflux ratio of sludge 100%, the A/O MBR removed COD, NH4+ -N, and TN effectively and stably with the average removal rates of 96.4%, 99.1% and 75.8%, respectively. The bacterial communities varied markedly in both anoxic and oxic tanks during the sewage treatment experiment. Under a same working condition, the communities in both tanks were often similar with a similarity of more than 50%. The community diversity of the anoxic tank fluctuated depending on different working conditions, while the diversity of the oxic tank increased steadily along with the operation time. A positive correlation between the bacterial community diversity of the anoxic tank and the denitrification efficiency of the A/O MBR was established.

[Biodegradation and adsorption of bio-zeolite on pyridine and quinoline].

The study was to explore the treatment of pyridine, quinoline and their transformation product, NH(4+) -N, by the biodegradation and adsorption of a natural and a modified bio-zeolites. The experiment results demonstrated that the mixed bacteria on the bio-zeolites, a pyridine-degrading bacterium and a quinoline-degrading bacterium, could degrade pyridine and quinoline simultaneously. The NH(4+) -N transformed from pyridine and quinoline could be adsorbed by the natural and modified zeolites. The adsorption capacity of the modified zeolite was lower than that of the natural zeolite. However, more microorganisms could attach on the surface of the modified zeolite, so the application of the modified bio-zeolite has a better prospect in actual treatment of pyridine and/ or quinoline pollution.

[Study on the function of plasmid in pyridine-degrading bacteria].

In order to identify the characteristics of the plasmids of degrading bacterial strains and the relationship between the plasmids' function and biodegradation, plasmids were isolated from two bacterial strains (Paracoccus sp. BW001 and Shinella zoogloeoides BC026) and pulse-field gel electrophoresis was used to identify the distribution of plasmids and their molecular size. Two large plasmids with 190-245 kb and one small plasmid with 4.5-5.0 kb were found in the BW001, and at least 3 large plasmids over 200 kb were harbored in the BC026. The plasmid curing was conducted by high temperature-SDS method and the results indicated the biodegradation genes might locate in the plasmids of two bacterial strains. After transforming the plasmids of BW001 into E. coli 5alpha by electroporation, the new bacterial strain could tolerate pyridine.

[Removal of pyridine using suspended and attached growing bacterium of Paracoccus denitrificans W12].

In this study, a pyridine-degrading bacterium, Paracoccus denitrifican W12, was isolated. It was cultivated to grow on the surface of activated bamboo charcoal (ABC) particles so that the ABC turned into biological activated bamboo charcoal (BABC) covered with biofilm of the W12. Free cells of the W12 and the BABC were separately tested in removing pyridine from aqueous solution. The results showed that 0.31 g x L(-1) suspended growing-W12 completely degraded 48.70-1399 mg x L(-1) of pyridine within 26.5-48.9 h, while the BABC (attached growing-W12) degraded pyridine much more efficiently due to the combination of biodegradation and adsorption. When the dosage of BABC was 10.0 g x L(-1) at the temperature of 35 degrees C, 692.2 mg x L(-1) of pyridine was decreased by 52% in the first 3.6 h mainly by adsorption, then was totally removed within 23.7 h mainly by biodegradation. Increasing the dosage of BABC or batch of treatment promoted the efficiency of pyridine removal remarkably. The synergistic mechanism of BABC removing pyridine from aqueous solution was further discussed on the basis of its microstructure.

[Pilot experiment on the treatment of the river wastewater by a step-feed biological contact process].

In the Dianchi Lake watershed, the Daqinghe River with the highest load of pollution was chosen as the treatment target, a new step-feed biological contact (SFBC) process was studied to treat the wastewater from the riverway. The pilot experiment was carried out through a winter dry season, a spring dry season and a summer rainy season. The results showed that the SFBC process was well-adapted to the variation of the river wastewater qualities. By adjusting the process parameters in different seasons, the removal rates of COD and TP could be stable at about 50% and 40% respectively; however, the removal rate of TN was influenced by the water temperature and DO greatly, and kept at about 20% when the process went to its stabilization. Seeding with activated sludge could accelerate the start-up of the equipment, but the whole treatment efficiency was not as good as that of the equipment without seeding but domesticating the microorganism in the river wastewater. However, along with the running of the SFBC process as well as the impact of the influent sediment from the river, the difference of the treatment efficiencies between the two equipments of whether or not seeding with activated sludge would disappear gradually.

[Biodegradation of pyridine by Shinella zoogloeoides BC026].

A bacterial strain BC026 capable of utilizing pyridine as its sole source of carbon and nitrogen was isolated from the activated sludge in a coking wastewater treatment plant. The bacterium featured flocculability and antibiotic resistance to kanamycin, ampicillin and spectinomycine. It could grow well in Ashby nitrogen free culture medium. The strain was identified as Shinella zoogloeoides according to the results of 16S rRNA sequence analysis and Biolog microbial identification system. The experiments of pyridine biodegradation by the pure culture showed that pyridine of 400 mg/L could be degraded completely in 17 h under the condition of inoculum 0.1 g/L, 30 degrees C, 180 r/min and pH 7. BC026 could keep high degradative activity in mineral salt medium containing pyridine with a concentration ranging from 99 mg/L to 1 806 mg/L. Higher initial concentration of pyridine caused repression on BC026 to a certain extent, however, the degradation rate became faster after the strain had been accommodated. The optimal conditions for the degradation were 30-35 degrees C and pH 8. The research on metabolic pathway of pyridine by BC026 indicated that the first step of pyridine degradation was C-N bonds cleavage, generating NH4+ and glutaraldehyde. Then glutaraldehyde was oxidized into glutaric acid, and finally into CO2 and H2O. 59.5% nitrogen from pyridine was transferred into ammonium in the whole degradation.

[Isolation, identification, and biodegradation characteristics of a quinoline-degrading bacterium].

A bacterial strain BW003, which could utilize quinoline as sole carbon, nitrogen and energy source, was isolated from the activated sludge in a coking wastewater treatment plant. According to the 16S rRNA gene sequence analysis, the strain was identified as Pseudomonas sp. Biodegradation experiments showed that the strain could degrade 192-911 mg/L of quinoline efficiently within 3-8 h, and the removal rates of quinoline were ranged from 96% to 98%. The optimum conditions for the degradation were 30 degrees C and pH 8. Metabolic products analysis revealed that at least 43% quinoline was first transformed into 2-hydroxyquinoline, 0.69% 2-hydroxyquinoline was then transformed into 2,8-dihydroxyquinoline, and subsequently into 8-hydroxycoumarin in the process of biodegradation. Additionally, at least 48% of nitrogen in quinoline was transformed into NH3-N directly and external carbon source could promote the nitrogen transformation, demonstrating that the quinoline and its metabolic products could be eliminated if controlling proper C/N ratio.

Control of bromate and THM precursors using ozonation combined system.

OBJECTIVE: To investigate the feasibility of reducing THM precursors and controlling bromate taste and odor in drinking water taken from the Yellow River by an ozonation combined system. METHODS: The appropriate ozone dosage was determined, and then the changes of TOC, UV254 and THM formation potential (THMFP) in the combined system were evaluated. RESULTS: One mg/L ozone could effectively remove taste and odor and meet the maximum allowable bromate level in drinking water. The pre-ozonation increased THMFP, but the conventional treatment system could effectively reduce the odor. The bio-ceramic filter could partly reduce CHCl3FP, but sometimes might increase CHCl2BrFP and CHClBr2FP. The biological activated carbon (BAC) filter could effectively reduce CHCl3FP and CHCl2BrFP, but increase CHClBr2FP. Compared with other filters, the fresh activated carbon (FAC) filter performed better in reducing THMFP and even reduced CHClBr2FP. CONCLUSION: The combined system can effectively reduce taste, odor, CHCl3FP, and CHCl2BrFP and also bring bromate under control.

Reduction of precursors of chlorination by-products in drinking water using fluidized-bed biofilm reactor at low temperature.

OBJECTIVE: To investigate the reduction of chlorination by-products (CBPs) precursors using the fluidized-bed biofilm reactor (FBBR). METHODS: Reduction of total organic carbon (TOC), ultraviolet absorbance (UV254), trihalomethane (THM) formation potential (THMFP), haloacetic acid (HAA) formation potential (HAAFP), and ammonia in FBBR were evaluated in detail. Results The reduction of TOC or UV254 was low, on average 12.6% and 4.7%, respectively, while the reduction of THMFP and HAAFP was significant. The reduction of ammonia was 30%-40% even below 3 degrees C, however, it could quickly rise to over 50% above 3degrees C. Conclusions The FBBR effectively reduces CBPs and ammonia in drinking water even at low temperature and seems to be a very promising and competitive drinking water reactor for polluted surface source waters, especially in China.

Biological pretreatment of Yellow River water.

Bio-ceramic filter(BF) and moving-bed biofilm reactor (MBBR) were used for biological pretreatment of Yellow River water in this study. The BF only had slight advantage over MBBR for TOC and ammonia removal. However, like UV254, the average removal rate of THMFP in the BF was much higher than that in the MBBR. UV254 removal did not show obvious correlation with trihalomethane formation potential (THMFP) removal. Hexachlorocyclohexane could be effectively removed in both BF and MBBR. As for diatom and cyanobateria removal the MBBR had better performance than the BF, which was contrary to the average chlorophyll-a ( Chl-a) removal rate. The proposal was made in this study that biological flocculation and sedimentation of sloughed biofilm should play a more important role on algae removal in the MBBR than in the BF. The BF and MBBR could effectively remove microcystins. Moreover, MBBR could be a promising technology for biological pretreatment.