[Effects of Nitrogen Speciation Transformation on Microbial Community Succession in Input Rivers of Miyun Reservoir].

The Miyun Reservoir is the major source of surface drinking water in Beijing. However, the total nitrogen (TN) concentrations in the Miyun Reservoir and inflowing rivers have recently been increasing. In this study, the Mangniu River, a typical inflow river in the upper reaches of the Miyun Reservoir, was selected as the study area to investigate the spatial distribution and transformation of various nitrogen forms from the perspective of microbial community composition and predicting function, aimimg at providing a scientific reference for nitrogen pollution control of the Miyun Reservoir. The results indicated that except for TN, all the other physical and chemical water quality indicators in the upper reaches of the Miyun Reservoir met the Class II criteria of the environmental quality standards for surface water in China (GB 3838-2002). Additionally, NO3--N was the primary constituent of TN, ranging from 77.7% to 92.9%. Banchengzi Reservoir has a certain self-purification ability because its high C/N ratio promotes denitrification. Significant differences in microbial community structure were observed between the water and sediments of Mangniu River along with spatial distribution. High NO3--N concentration was the major environmental factor affecting the succession of microbial community structure. Many nitrification and denitrification microorganisms existed in Mengniu River, and the relative abundance of denitrification bacteria (DNB) was higher than that of nitrification bacteria, and that in the sediments was slightly higher than that in the water. Nitrosopumilus and Pseudomonas were the dominant nitrification and denitrification bacteria in Mengniuhe River, respectively. The results of phylogenetic investigation of communities by the reconstruction of unobserved states (PICRUSt2) showed that NO3--N reduction module was the major nitrogen metabolism module, which primarily occurred in water. The abundance of the functional genes for nitrification (i.e., narGH) was the highest in water, and the major functional gene involved in NO3--N reduction was nirBD of DNRA, which was primarily present in the sediments; however, the main functional gene involved in denitrification was nirK.

[Succession and PICRUSt2-based Predicted Functional Analysis of Microbial Communities During the Sludge Bulking Occurrence and Restoration in One-stage Combined Partial Nitritation and ANAMMOX Process].

This study was based on the pilot one-stage combined partial nitritation and ANAMMOX process (CPNA), using data mining and analysis of 16S rRNA high-throughput sequencing data of activated sludge in the process of sludge bulking and recovery, combined with PISCRUSt2. The function prediction analysis aimed to reveal the microbial community changes and the characteristics of nitrogen metabolism and carbon metabolism at different stages of sludge bulking and recovery of the one-stage CPNA process. The results of the study showed that the microbial α-diversity in the sludge bulking and recovery process first increased and then declined. The relative abundance of Nitrosomonas, Candidatus_Brocadia, and Thaurea decreased in the sludge-bulking stage from 12.36%, 11.86%, and 0.272% to 5.97%, 8.30%, and 0.061%, whereas the relative abundance of Candidatus Kuenenia remained stable. The relative abundance of Levilinea, Longilinea, and Turicibacter increased from 0.031%, 0.018%, and 0.009% to 0.055%, 0.025%, and 0.033%. The PICRUSt2 function prediction analysis results showed that there were a total of 47 functional enzyme genes involved in nitrogen metabolism, of which nitrification, denitrification, dissimilative nitrate reduction (DNRA), assimilation nitrate reduction (ANRA), and nitrogen fixation were relatively abundant. The degrees of each had changed. During the sludge-bulking stage, the relative abundance of the ammonia monooxygenase gene (pmoABC-amoABC) and the hydroxylamine dehydrogenase gene hao decreased, whereas the relative abundance of the nitrate-reducing gene increased at the initial stage and then showed a downward trend. Carbon metabolism analysis showed that sodium acetate had a promoting effect on the heterotrophic growth of the CPNA process, but the energy metabolism and glucose production of sodium acetate were not active.

[Impacts of Riparian Buffer Zone Type on Reduction in Runoff Pollution in the North Canal River Under Different Rainfall Events].

The impact of non-point source pollution on the water quality of the North Canal River is becoming increasingly prominent. In this study, the riparian buffer zones (RBZ) of the Nansha River and Beisha River, the inlet tributaries of the Shahe Reservoir in the North Canal basin, were selected to investigate the purification effect of riparian buffer zones on runoff pollution during the rainfall process. Two RBZ types, Type I RBZ (levee-flood control retaining wall-woodland-grassland) and Type Ⅱ RBZ (levee-woodland-grassland), were classified by the distribution characteristics of RBZ structure and plant communities in the North Canal River basin. The north bank of the Nansha River (NB) and the south bank of the Beisha River (BN) are typical of Type I RBZ, with low total vegetation cover, "short and steep" slopes, and low herbaceous cover but high diversity. The south bank of the Nansha River (NN) is a typical representative of Type Ⅱ RBZ, with "long and slow" slopes and high herbaceous cover (29.16%) but low diversity. In order to investigate the impacts of rainfall characteristics and RBZ types on the runoff pollutant, a 1 km area in each of the three RBZs was selected to carry out the RBZ non-point source pollution prevention and control engineering trials. The results indicated that Type I RBZ required less time and rainfall to produce runoff and had a greater peak runoff. Type Ⅱ RBZ produced runoff only under heavy rainstorm conditions, with greater runoff retention capacity. Energy dissipation ponds with gravel as the main fillers were set up at the runoff inlets of the RBZ, which effectively reduced runoff pollution. ρ(NH4+-N) and ρ(NO3--N) in the runoff were below 1.6 mg·L-1; ρ(TN) was below 5 mg·L-1; and ρ(PO43-P), ρ(DTP), and ρ(TP) were below 1.0 mg·L-1. The grass ditch of the RBZs effectively reduced ρ(NH4+-N) of the runoff. The retention rate of SS and the reduction effect of pollutants in Type Ⅱ RBZ were better than those in Type I except under heavy rainstorm conditions, which is related to the different RBZ structures and vegetation cover. The correlation analysis results showed that slope length, slope gradient, vegetation cover, and rainfall characteristics were significantly correlated with runoff SS, COD, nitrogen, and phosphorus pollution.

[Nitrite Regulation During Start-up of Combined Partial Nitritation and ANAMMOX Process].

Two types of full-scale reactors(SBR, 116.6 m3, activated sludge process; SBBR, 64.8 m3, activated sludge and biofilm process) were inoculated with activated sludge from a swine wastewater treatment plant. The effect of NO2--N concentration on ANAMMOX was investigated in the reactors during the start-up of the combined partial nitritation and ANAMMOX(CPNA) process by controlling the dissolved oxygen(DO), aeration mode, and NaNO2 dosing. The results showed that the SBBR was more suitable for rapid start-up of partial nitritation under the same operation conditions. Despite NO2--N inhibition(100-129 mg·L-1, 7 days), the ANAMMOX process was successfully started by the SBR on day 39, and the total nitrogen removal rate and efficiency(TNRR and TNRE) were 0.069 kg·(m3·d) -1 and 23.3%, respectively. However, 17 days of NO2--N inhibition(129-286 mg·L-1) had an unrecoverable effect on ANAMMOX activity in the SBBR. By adding NaNO2, the SBR successfully started the CPNA process on day 77. The TNRR, TNRE, and activity of ANAMMOX from day 51 to 77 increased rapidly from 0.070 to 0.336 kg·(m3·d) -1, 16.0% to 52.2%, and 0.012 to 0.307 kg·(kg·d) -1, respectively. The gene copy concentration of AOB and ANAMMOX bacteria in the SBR increased from the original 8.06×106 and 4.42×104 copies·mL-1 to 1.02×109 and 1.77×107 copies·mL-1, respectively, which indicated that the rapid enrichment of AOB and ANAMMOX bacteria in the SBR was achieved mainly by controlling DO, aeration mode, and NaNO2 dosing. Reasonable nitrite regulation is the key for the start of the CPNA process.

[Mutual Influence Between Microbial Community, Wastewater Characteristics, and Antibiotic Resistance Genes During Spiramycin Production Wastewater Treatment].

Wastewater from antibiotic production usually contains a huge amount of antibiotic resistance genes (ARG). Therefore, it is essential to study the dissemination and control of antibiotic resistance during the treatment of antibiotic production wastewater. The mutual influence between microbial community evolution, wastewater characteristics, and ARG was investigated using high-throughput sequencing and a variety of statistical analysis methods. Results showed that the influent characteristics had only a marginal influence on the microbial community of each treatment section. Methanogenic bacteria and sulfate-reducing bacteria were the dominant microbes in the anaerobic and anoxic tank. Chemical oxygen demand (COD), NO2--N, and PO43--P exhibited an intimate relationship with the microbial community, whereas biomass, NH4+-N, and COD showed a strong correlation with ARG and mobile genetic elements (MGE). In the sludge, more genera (including pathogenic bacteria) were significantly correlated with ARG and MGE than that in the wastewater, indicating that bacteria in the sludge had a greater chance of acquiring pathogenicity and resistance. Therefore, more attnetion should be given to waste sludge from the treatment plants of antibiotic production wastewater. This research could provide further understanding of antibiotic resistance dissemination and control during wastewater treatment, especially for antibiotic production wastewater.

[Diversity and PICRUSt2-based Predicted Functional Analysis of Bacterial Communities During the Start-up of ANAMMOX].

Bacterial communities are vital for efficient nitrogen removal in an anaerobic ammonium oxidation (ANAMMOX) system. However, the diversity and functional characteristics of a bacterial community during the start-up of ANAMMOX has not been reported. In this study, an up-flow anaerobic sludge bed reactor was used to start-up the ANAMMOX system, and 16S rRNA high-throughput gene sequencing, combined with PICRUSt2-based functional prediction analysis, was used to investigate the dynamic changes in diversity and function of the bacterial community at different times (d0, d30, d60, and d90) during the start-up. The results showed that 48 phyla, 111 classes, 269 orders, 457 families, 840 genera, and 1497 species were present during the start-up of ANAMMOX. Candidatus Brocadia and Candidatus_Kuenenia were the main detected ANAMMOX bacteria, and their relative abundance was significantly different at different times during the start-up of ANAMMOX (P<0.05). During the start-up, the alpha diversity indices of the bacterial community were significantly decreased (P<0.05), and the structure of the bacterial community exhibited significant spatial differentiation (R=0.846, P<0.01). Functional prediction analysis with PICRUSt2 revealed that the bacterial community was active in organic systems and metabolism at hierarchy level 1, implying abundant functional diversity. Further, the abundance of functional genes was significantly different at hierarchy level 2, during the start-up of ANAMMOX. Forty-nine functional genes involving metabolic nitrogen were detected. The abundance of functional genes, involved in nitrification, denitrification, ANAMMOX, and nitrate and nitrite assimilatory/dissimilatory reduction, changed significantly during the start-up of ANAMMOX.

[Occurrence of Antibiotic Resistance Genes and Bacterial Community Structure of Different Sludge Samples During Microwave Pretreatment-Anaerobic Digestion].

The waste sludge of municipal wastewater treatment plants is an important reservoir for antibiotic resistance genes (ARG). It is necessary to explore the fate of ARG, microbial community succession, and the correlations between them. Therefore, the distribution of ARG and the microbial community structure of waste sludge from wastewater treatment plants with A2O and A2O-MBR processes during microwave pretreatment and anaerobic digestion were studied in this research. The results showed that the occurrence of ARG and the microbial community structure were quite different in the waste sludge of A2O and A2O-MBR processes. The microwave pretreatment did not change the microbial community much, whereas the community structure of the digested sludge with pretreatment showed significant differences. Anaerobic digestion had a conformity effect on the distribution of ARG and MGE in the digested sludge with or without pretreatment. Among genes, ermF, qnrS, and blaNDM-1 were the most difficult to be reduced ARG and were prone to propagation during anaerobic digestion. The influence of biomass, ammonia nitrogen, and phosphorus on the distribution of ARG and MGE was higher than that of other environmental factors. The sludge characteristics also showed important impacts on the microbial community, especially on some genera with specific functions. These results could help people to better understand the spread and control of ARG during sludge anaerobic digestion.

[Microbial Community Structure and Diversity During the Enrichment of Anaerobic Ammonium Oxidation Bacteria].

To understand the changes in microbial community characteristics during the enrichment of anaerobic ammonium oxidation (ANAMMOX) bacteria, an ASBR reactor was used to culture the ANAMMOX bacteria. The composition, diversity, and species co-occurrence network of the microbial community were investigated under different cultivation times. The results showed that the ANAMMOX bacteria were enriched by gradually increasing the substrate concentration, with removal efficiencies for NH4+-N, NO2--N, and total nitrogen of 97.6%, 95.4%, and 84.9%, respectively. The high-throughput sequencing found that the dominant phyla (relative abundance>5%) were Proteobacteria, Bacteroidetes, Chloroflexi, Planctomycetes, Armatimonadetes, and Actinobacteria in the whole culture process. Candidatus Brocadia was the main ANAMMOX bacteria in the reactor, with its relative abundance increasing from 1.42% to 24.66%. During the cultivation process, the composition of the dominant microbial community did not change, while the relative abundance showed a significant difference (P<0.05). The alpha diversity of the microbial community significantly increased first and then decreased (P<0.05), and the beta diversity of the microbial community was significantly spatially differentiated (R=0.5672, P<0.01) during the culture process. Species network densities were 0.188, 0.068, 0.059, 0.18, and 0.0735 at different times during the culture process. Although the enrichment culture process resulted in weaker correlations between microorganisms, the related group of microorganisms in the phylum Aspergillus became the main node in the network. The enrichment process weakened the correlation between microorganisms; however, the microbial taxa related to the phylum Planctomycetes became the key node in the network.

[Distribution of Antibiotic Concentration in Domestic Wastewater Treatment Facilities in Villages and Towns].

Antibiotics discharged into the environment cause increased environmental resistance. Four types of antibiotics (quinolones, tetracyclines, macrolides, and ß-lactams) were selected for this study. In a comparison with the municipal wastewater plant, the concentration and removal of antibiotics in influent and effluent of domestic wastewater treatment facilities of different scales in villages and towns was investigated using high-performance liquid chromatography (HPLC) and tandem mass spectrometry (MS). The results showed that the highest amount of ofloxacin in rural wastewater treatment facilities reached 32663.5 ng·L-1. Due to the different situations of influent fluctuation, discharge requirements, and management between urban and rural wastewater plants, only 33% of the rural domestic wastewater facilities detected an antibiotics removal rate of more than 60%. The effective removal of some antibiotics can be achieved when the rural domestic wastewater treatment facilities maintain the standard discharge of conventional pollutants.

[Effect on Ammonia Inhibition Mitigation in the Anaerobic Digestion Process with Zero-Valent Iron].

Ammonia inhibition is an important factor impacting methane production efficiency during the anaerobic digestion of high-solid organic wastes. This study investigated the effect of micro-sized zero-valent iron (m-ZVI) on the anaerobic digestion of excess sewage sludge and thermal hydrolyzed sludge using batch mode experiments. The effect of m-ZVI on ammonia inhibition mitigation was also studied. Results showed that the kinetic characteristics of the methane production rate, lag phase, and methane production potential of the anaerobic digestion of excess sludge and thermal hydrolyzed sludge were not impacted by the addition of m-ZVI at a dosage of 4 g·L-1 and 10 g·L-1. However, during the inhibited anaerobic digestion process with a high ammonia concentration, the addition of 4 g·L-1 and 10 g·L-1 of m-ZVI was able to shorten the lag phase from 18.61 d (the control) to 17.22 d and 16.18 d, respectively. Moreover, the maximum methane production rate (based on the VS) increased from 6.34 mL·(d·g)-1(the control) to 7.84 mL·(d·g)-1 (4 g·L-1 m-ZVI) and 7.39 mL·(d·g)-1 (10 g·L-1 m-ZVI). The pH buffer system was not influenced by the chemical reaction of m-ZVI in the anaerobic digestion, although the relative abundance of the dominant methanogenic archaea (Methanosarcina) improved greatly from 30.71% (the control) to 53.50% (4 g·L-1 m-ZVI) and 60.30% (10 g·L-1 m-ZVI) at 27 d. This study proved that m-ZVI was incapable of improving the methane production potential of sewage sludge, while the mitigation of ammonia inhibition during anaerobic digestion was enhanced by the stimulating effect on methanogenic archaea.

[Effect of Sulfate on the Migration and Transformation of Methylmercury in Advanced Anaerobic Digestion of Sludge].

To study the migration and transformation of methylmercury during advanced anaerobic digestion of sludge and the role of sulfate, this study investigated the migration and transformation of methylmercury during different stages of sludge anaerobic digestion (AD) with thermal hydrolysis pretreatment and under different dosages of sulfate addition. The results showed that mercury methylation occurred in the initial stage of AD (Day 1-3), the ratio of methylmercury to total mercury increased from 0.024% (range of 0.019%-0.033%) to 0.038% (range of 0.030%-0.048%), and the net increment of methylmercury increased by 3.97, 6.09, 0.17, 3.71, and 1.66 times, respectively. In the following Day 3-5, the demethylation process occurred with the net yield of methylmercury decreased by 71.25% (ranging from 67.42% to 75.10%). Sulfate inhibited the methylation of mercury in the initial stage of AD, but had little effect on it in the late stage. This was related to the reduction of the bioavailability of neutral mercury complexes by charged groups of HgHS22- and HgS22-, as well as the immobilization of iron sulfide and mercury sulfide on S2- and bioavailable mercury. Redundancy analysis (RDA) showed that mercury methylation was affected by several factors:organic substances such as propionic acid, isobutyric acid, isovaleric acid, and Fe may promote mercury methylation, whereas protein and higher pH may be inhibitors of mercury methylation in AD of sludge.

[Spatio-temporal Evolution and Relationship of Water Environment Quality and Phytoplankton Community in Wenyu River].

The Wenyu River is an important ecological corridor of Beijing. In this study, the spatio-temporal dynamics of water quality and phytoplankton community in the Wenyu River in 2006, 2011, and 2018, as well as their relationship were thoroughly analyzed by historical data analysis and field surveys. Results show that the water quality in the Wenyu River improved significantly from serious pollution owing to pollution containment. The major water pollutant has shifted from ammonia nitrogen (NH4+-N) to total nitrogen (TN). Compared with 2011, the average multiple of NH4+-N and total nitrogen TN exceeding the national standard were reduced by factors of 0.29-0.33 and 2.77-2.39, respectively, in 2018. The average concentration of NH4+-N and TN decreased from 15.52-19.16 mg·L-1 and 20.21-19.58 mg·L-1 in 2011 to 1.93-2.66 mg·L-1 and 5.66-6.79 mg·L-1 in 2018. Moreover, dissolved oxygen (DO) and NH4+-N concentrations in the Wenyu River and its tributaries, the Qinghe River, almost met requirements of their water function zoning target. Corresponding with the water quality improvement, the phytoplankton and community species increased dramatically. Phytoplankton species increased from 6 to 8 phyla, as well as community species. The dominant species changed from Chlorophyta in 2006 to the Cyanophyta in 2011, then to Bacillariophyta in 2018. The Shannon-Wiener diversity index (H') and evenness Pielou index (J) had improved. However, the major dominant species such as Cyclotella and Melosira persisted, and the Wenyu River was still in the eutrophication state in 2018. Statistical analysis results indicated that Cyanophyta, Bacillariophyta, and other algae abundance were significantly correlated with DO, pH, NH4+-N, TN, and TP.

[Removal Performance of Antibiotic Resistance Genes and Heavy Metal Resistance Genes in Municipal Wastewater by Magnetic-Coagulation Process].

Antibiotic resistance genes (ARGs) in municipal wastewater pose a potential threat to the environment. In this study, the change in absolute and relative abundance of ARGs, metal resistance genes (MRGs), and mobile genetic elements (MGTs) were investigated during an emergent municipal wastewater treatment by the magnetic separation process. Results indicate that all the concentrations of targeted ARGs, MRGs, and MGTs decreased significantly in the primary and secondary stirring tank. However, the absolute abundance of some ARGs and MRGs increased in the effluent, which is likely caused by the presence of ample MGTs, in the order of int1 (2.00×1010 copies·mL-1) > int2 (1.91×108 copies·mL-1) > Tn 916/1545e(5.38×108 copies·mL-1). The results obtained from network and PCA analysis showed that the removal of ARGs and MRGs were significantly associated with variations in the microbial community and common pollutants in urban wastewater, such as suspended solids, phosphorus, and COD, which are important factors for affecting the removal efficiency of antibiotic resistance genes and metal heavy resistance genes. These results show that magnetic separation can effectively reduce common pollutants in urban wastewater and might further restrict the transmission and transfer of ARGs. Moreover, it is necessary to strengthen the subsequent management of magnetic separation effluent and dehydrated sludge by disinfection technologies to lessen the risk of antimicrobial contamination.

[Fate of Antibiotic Resistance Genes and Virulence Genes in Enterococci During Anaerobic Digestion Process of Thermal Hydrolyzed Sludge].

Municipal sludge contains large amounts of enterococci, which can harbor antibiotic resistance genes (ARGs) and virulence genes (VGs). ARG- and VG-containing enterococci therefore present potential resistance and virulence and, as a consequence, represent a significant health risk to humans. Therefore, the resistance phenotype of enterococci and the prevalence of ARGs and VGs in the enterococci isolated from the mesophilic (40℃) and thermophilic (55℃) anaerobic digestion of thermal hydrolyzed sludge was investigated. Results showed that the enterococci isolated from thermal hydrolyzed sludge showed significantly higher resistance to azithromycin than that to spiramycin and tetracycline. Thermophilic anaerobic digestion resulted in a greater reduction of enterococci abundance (by two orders of magnitude and one order of magnitude, respectively), and a greater reduction in the antibiotic resistance rates of the enterococci. However, thermophilic digestion can promote the expression of tetracycline resistance genes in the enterococci. Furthermore, both mesophilic and thermophilic digestion can facilitate horizontal genes transfer (HGT) between enterococci, which might result in an increase in the occurrence of double- or multiple-resistance. Mesophilic digestion reduced the prevalence of co-occurring ARGs and VGs in enterococci, while thermophilic digestion had the opposite effect. This research improves understanding of the occurrence and fate of ARGs and VGs in potential pathogens during the treatment of municipal sludge.

[Enhancement for Anaerobic Digestion of Waste Activated Sludge Based on Microwave Pretreatment Combined with Zero Valent Iron].

In this study, we investigated the enhanced performance after addition of zero valent iron (ZVI) under different dosages (low range of 5.19-41.51 g·kg-1 TS and high range of 83.35-853.46 g·kg-1 TS), combined with microwave (MW) pretreatment for anaerobic digestion (AD) of waste activated sludge (WAS). The results demonstrated that the methane production potential of WAS could be increased by 17%-24% with the addition of ZVI combined with MW pretreatment, and especially the methane production rate was enhanced in the initial days (1-4d). ZVI addition could further improve the enhanced performance of AD under MW pretreatment. Compared with the performance of AD with only MW pretreatment, the methane production potential was increased by 7.42%, and methane production flow rate at 2 d was increased by 11.02% with 31.13 g·kg-1 TS of ZVI addition. However, the higher dosage of added ZVI did not show further enhanced performance. It was concluded that ZVI addition promoted the release of dissolved organics at the initial stage of AD. For instance, soluble proteins were increased by 21.16% with the ZVI addition of 31.13 g·kg-1 TS compared with pretreated WAS without ZVI addition. Furthermore, ZVI addition accelerated the degradation of acetic acid, iso-butyric acid, and iso-valeric acid, and led to a significant reduction of orthophosphate and sulfate in the supernatant of the digested sludge. The concentration of iron in the supernatant decreased even with a high dosage of ZVI. Thus, the formation of precipitate that occurred due to reactions between iron and orthophosphate or sulfate, may be the main reason for the lack of enhanced performance even with high dosage of ZVI addition.

[Distribution and Treatment of Antibiotics in Typical WWTPs in Small Towns in China].

As a new, persistent pollutant in the environment, antibiotics are one of the most important pollutants in sewage treatment plants. The objective of this work was to investigate the concentration distribution and removal efficiency of antibiotics for three typical wastewater treatment technologies applied in small towns (CASS, A2/O, and Orbal oxidation ditch) using solid phase extraction-liquid chromatography-tandem mass spectrometry. Sixteen typical antibiotics, including four tetracyclines, three ß-lactams, four macrolides, three quinolones, and two sulfonamides, were analyzed in the influent and effluent. In addition, the relationship between the presence of antibiotics and the basic water quality (NH4+-N, TN, COD, pH, etc.) in the WWTPs was analyzed. The results showed that ofloxacin (OFX) and norfloxacin (NOR) were the main antibiotics in the WWTPs in this study. However, the concentrations of these two antibiotics in the effluent were low, indicating effective antibiotic removal efficiency. The antibiotic removal efficiency was higher than 60% in five of the WWTPs. Compared with the A2/O process, the CASS and Orbal oxidation ditch technologies resulted in higher removals of most of the antibiotics. In addition, the CASS and A2/O processes worked best for the removal of ß-lactam [ampicillin (AMP) and penicillin (PCN)], quinolones (ENR, NOR, and OFX), and macrolide (CLR), while the Orbal oxidation ditch worked best for the removal of tetracyclines (TC and OTC) and sulfonamides [sulfadiazine (SD)]. The correlation between antibiotic concentration and the basic parameters of water quality (NH4+-N, TN, COD, pH, etc.) was analyzed, and it was found that the water quality parameters had some effect on the concentration of antibiotics. With higher concentrations of the basic water quality parameters, higher the concentration of erythromycin (EM), roxithromycin (ROX), 4-epi-Tetracycline (E-TC), clarithromycin (CLR), ciprofloxacin (CIP), ofloxacin (OFX), epioxytetracycline (E-OTC), tetracyclines (TC), oxytetracycline (OTC), and norfloxacin (NOR) were observed. In summary, it is important to ensure the stable operation of small town WWTPs to reduce the ecological risk of antibiotics.

[Impacts of Sludge Characteristics on Anaerobic Digestion with Microwave Pretreatment and Archaeal Community Structure Analysis].

Sludge characteristics is an important factor in sludge pretreatment and anaerobic digestion (AD) efficiency. Therefore, waste sludge of anaerobic-anoxic-aerobic (A2O) and A2O-membrane bioreactor (MBR) wastewater treatment processes from a full-scale wastewater treatment plant were taken, and the variations of sludge characteristics and performance during microwave pretreatment and AD were compared. The succession of archaeal community structure during the sludge treatment was also investigated. A2O waste sludge showed better biodegradability than A2O-MBR waste sludge did, with 16.4% higher organic matter content (66.4% vs. 50.0%), soluble chemical oxygen demand (COD) (1.24 fold), soluble protein (2.02 fold), and polysaccharides (4.84 fold). Although the efficiency of microwave pretreatment for A2O-MBR waste sludge was better than that for A2O waste sludge, the latter sludge produced 26.1% more methane than the former did. The two types of waste sludge showed different archaeal community structures. The abundances of Methanothrix and Methanosarcina in A2O-MBR waste sludge were 3.68% and 19.73% higher than that in A2O waste sludge. The richness and evenness of archaeal communities slightly changed after pretreatment, but significantly changed after AD. The Chao1 index increased by 54.0%-68.8% after AD, whereas the Pielou index decreased by 16.2%-34.6%. Redundancy analysis showed that the organic components of waste sludge contributed to the succession of archaeal community structure.

[Effect of Aeration Strategies on Emissions of Nitrogenous Gases and Methane During Sludge Bio-Drying].

The data on nitrogen gas (NH3, N2O, NO) emissions during sludge bio-drying process in China is scarce, especially NO due to its unstable chemical property. In this study, effect of two aeration modes on emissions of methane and nitrogenous gas was compared during the continuous aerated turning pile sludge bio-drying process at full scale. In these two aeration strategies, the one currently used in the plant was set as the control, and the other was set as the test in which the aeration was used for oxygen supply, pile temperature control, and moisture removal in the start-up, middle and final stages, respectively. The results showed that the aeration strategy used in the test could not only obviously accelerate the rate of sludge drying (the moisture contents of the test and the control were 36.6% and 42% on day 11) , but also had a better drying performance (the final moisture contents of the test and the control were 33.6% and 37.6%, respectively) and decreased the ammonia cumulative emission by 5%, (ammonia cumulative emission of the test and the control were 208 mg x m(-3) and 219.8 mg x m(-3), respectively). Though a lower accumulated emission (eCO2) of greenhouse gas in the test at 3.61 kg x t(-1) was observed than that of the control (3.73 kg x t(-1) dry weight) , the cumulative emission of NO in the test at 1.9 g x m(-2) was 15. 9% higher than that of the control (1.6 g x m(-2)).

[Energy Consumption Comparison and Energy Saving Approaches for Different Wastewater Treatment Processes in a Large-scale Reclaimed Water Plant].

Energy consumption is the main performance indicator of reclaimed water plant (RWP) operation. Methods of specific energy consumption analysis, unit energy consumption analysis and redundancy analysis were applied to investigate the composition and spatio-temporal distribution of energy consumption in Qinghe RWP with inverted A2/O, A2/O and A2/O-MBR processes. And the A2/ O-MBR process was mainly analyzed to identify the main nodes and causes for high energy consumption, approaches for energy saving were explored, and the energy consumption before and after upgrading for energy saving was compared. The results showed that aeration was the key factor affecting energy consumption in both conventional and A2/O-MBR processes, accounting for 42.97% and 50.65% of total energy consumption, respectively. A pulsating aeration allowed an increasing membrane flux and remarkably reduced the energy consumption of the A2/O-MBR process while still meeting the effluent standard, e.g., the membrane flux was increased by 20%, and the energy consumptions per kiloton wastewater and kilogram COD(removed) were decreased by 42.39% to 0.53 kW-h-kg-3 and by 54.74% to 1.29 kW x h x kg(-1), respectively. The decrease of backflow ratio in the A2/O-MBR process within a certain range would not deteriorate the effluent quality due to its insignificant correlation with the effluent quality, and therefore may be considered as one of the ways for further energy saving.

[Influencing Factors for Hydrolysis of Sewage Sludge Pretreated by Microwave-H2O2-Alkaline Process].

Pretreatment can improve carbon source utilization of sludge. In this study, influencing factors of hydrolysis including hydrolysis time, ratio of seed sludge and temperature were investigated for sewage sludge pretreated by microwave-H2O2-alkaline process through batch experiments. Meanwhile, effects of hydrolysis and releasing characteristics of organic matters were also investigated under the optimized conditions. The results showed that the optimal hydrolysis time was 12 h and the optimized inoculum to substrate ratio (I/S) was 0.07. Under optimized conditions (12 h, I/S =0.07), SCOD, soluble proteins, soluble sugars and total VFAs content increased with increasing temperature, reaching the maximum at 65 degrees C. Acetic, propionic and iso-valeric acids were the dominant VFAs produced, and the percentage of acetic acid accounting for total VFAs was between 42.7% and 59.7%. In terms of carbon source composition, SCOD accounted for 37.8%-40.8% of total COD, soluble proteins accounted for 38.3%-41.3% of SCOD, soluble sugars accounted for 9.0%-9.3% of SCOD and total VFAs accounted for 3.3%-5.5% of SCOD. The COD/TN watio was between 15.79 and 16.50 in the sludge supernatant. The results of the three-dimensional fluorescence spectra and apparent molecular weight distributions showed that the fluorescence intensity of tyrosine-like substances in the soluble microbial products was the highest and increased with the increasing temperature in the sludge supernatant. After the sewage sludge was pretreated by microwave-H2O2-OH process, a lot of organic matters were released, including small molecule organics (M 100-350), while after hydrolysis, M, 3000-60,000 organics were degraded.