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Highlights • A volume model technique was developed for controlled liquid manure addition. • Swine effluent and small bulking material sizes enhanced organic matter degradation. • Liquid manure types influenced nutrients and heavy metals retention potentials. • Reduced leachate generation was achieved via optimized co-composting condition. Abstract This study was conducted to examine the effects of controlled addition of liquid (LM) to solid (SM) manure compost using a volume-model technique on the co-composting of SM and LM, and further to investigate the major effects of bulking material sizes and LM types on the co-composting process and final compost characteristics. Results indicated that this volume-model technique played a critical role in reducing leachate generation and improving the overall efficiency of the co-composting process. Specifically, the developed model enhanced the evaporation rates of windrows during the co-composting process. For improved final compost properties, small bulking materials and swine-effluent-based LM were found to be more efficient for organic matter degradation, LM consumption, hazardous metals immobilization, and essential nutrients retention than large bulking materials and biogas-based LM. Thus, process parameter optimizations represent major research options for successful co-composting applications for the future. [ABSTRACT FROM AUTHOR]

The development and properties of algae-bacteria granular consortia, which cultivated with the algae ( Chlorella and Scenedesmus ) and aerobic granules, was investigated in this experiment. The results indicated that the granular consortia could be successfully developed by selection pressure control, and the algal biomass and extracellular polymeric substances (EPS) concentration in the consortia showed notable correlation with the operating parameters of reactor. The maximum specific removal rates of total nitrogen and phosphate were obtained from the granular consortia with the highest algal biomass, yet the correlation between the fatty acid methyl esters yield and the algal biomass in the consortia was not markedly observed. The seed algae maintained dominance in the phototroph community, whereas the cyanobacteria only occupied a small proportion (5.2–6.5%). Although the bacterial communities with different operational strategies showed significant difference, the dominated bacteria ( Comamonadaceae , 18.79–36.25%) in the mature granular consortia were similar. [ABSTRACT FROM AUTHOR]

• Corncob enhanced organic matter degradation and liquid manure consumption. • Bulking material types had greater influences on composting than liquid manures. • Pollutants retention and final compost properties were improved by corncob. This study was conducted to examine the effects of different bulking materials (corncob and ricehusk) on liquid manure consumption, organic matter degradation and pollutants retention in composting process under controlled addition of different types of liquid manures (LM). The results indicated that under the controlled addition of LM, bulking materials with higher content of biodegradable carbon (corncob) and LM with a higher concentration of organic pollutants (swine effluent) were more beneficial for biological heat generation and thus were more efficient for water evaporation, organic matter degradation, LM consumption and pollutants retention during the cocomposting process. Consequently, the optimization of these major influencing factors could compensate for efforts geared towards better utilization of the cocomposting process. [ABSTRACT FROM AUTHOR]

The removal efficiencies and accumulated concentrations of oxytetracycline and ciprofloxacin in three pilot-scale constructed wetlands (CWs) with different flow configurations (surface, horizontal subsurface, and vertical subsurface flow) were investigated. The results indicated that the average mass removal efficiencies of the CWs for the target antibiotics in one year of treatment ranged from 85 to 99%, and the vertical subsurface flow constructed wetlands exhibited the highest and most stable removal efficiencies for oxytetracycline (99 ± 0.27%) and ciprofloxacin (97 ± 0.26%). The influence of seasonal changes on the removal efficiencies of oxytetracycline and ciprofloxacin in CWs was insignificant. The higher accumulated antibiotic concentrations and antibiotic-degrading bacteria abundances indicated that substrate adsorption and biodegradation were the predominant pathways affecting the antibiotic removal efficiency of wetlands. The concentration of accumulated ciprofloxacin in soil and oyster shell (84–124 and 83–115 μg kg−1) was significantly higher than that of oxytetracycline (37–81 and 3–17 μg kg−1). In addition, analysis results based on pilot-scale CWs also indicated that the influence of the type of CW on the bacterial community was more significant than the wetland substrate and residual concentration of antibiotics. • Flow configuration determine removal efficiencies of OTC and CIP in wetland. • Removal rate of antibiotic in wetland increased in following order: VSF > HSF > SF. • Neutral-pH level of substrate can enhance degradation rate of OTC in wetland. • Flow configuration show more effect on bacterial community in CW than antibiotic. [ABSTRACT FROM AUTHOR]

Abstract Three aerobic granular reactors with different mixed liquor suspended solids concentration (about 6432 mg L−1, 9053 mg L−1, 11840 mg L−1) were operated to assess the influence of biomass concentration on efficiency of tetracyclines and sulfonamides removal, and on the abundance of corresponding antibiotic resistance genes in the sludge. Results indicated that biomass concentration did affect effluent concentration of sulfonamides, yet no significant difference in tetracyclines removal was observed among the three reactors. Accumulated concentrations of all antibiotics had significant negative significant correlations with biomass concentration. Accumulated concentrations of total tetracyclines and total sulfonamides in sludge from the three reactors were 9.62 μg g−1 and 1.13 μg g−1, 6.74 μg g−1 and 0.70 μg g−1, and 3.70 μg g−1 and 0.30 μg g−1, respectively. Among investigated antibiotic resistance genes, only tet A had a significant negative correlation with biomass concentration, and the relative abundances of tet A in the three reactors at the end of this experiment were 5.75 × 10−2, 4.34 × 10−2 and 3.86 × 10−2, respectively. Results from this study suggested that biomass concentration is key operational parameter of granular reactors that can affect antibiotic removal efficiency, but it was not a major influencing factor in controlling abundance of antibiotics resistance genes in sludge. Highlights • Biomass concentration showed significant positive effect on sulfonamides removal. • Higher biomass concentration enhanced degradation efficiencies of tetracyclines. • Antibiotics accumulation had negative relationship with biomass concentration. • Relative abundance of tet A increased in reactor with lower biomass concentration. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the nutrient removal and microbial response during the treatment of antibiotics-enriched swine wastewater by vertical flow constructed wetlands with different water flow directions and substrates. Better NH 4 -N and TN removal were achieved in down-flow and up-flow treatments, respectively. The concentrations of all the chemical properties including oxytetracycline (OTC), difloxacin (DIF), copper (Cu) and zinc (Zn), nitrite/nitrate, sulphate and total organic carbon (TOC) in down-flow treatment soils were significantly higher than those in up-flow treatments on day 30, 60 and 90 (p < 0.05). Bacterial α-diversity indices in soils were negatively correlated with the concentrations of OTC, DIF, Cu and Zn significantly (p < 0.05). Among experimental factors, substrate type significantly contributed to variation of bacterial communities in waters, while water flow direction and sampling time significantly contributed to those in soils (p < 0.01). Among environmental factors, OTC + DIF, Cu + Zn, nitrate/nitrite and sulphate significantly contributed to variation of bacterial communities in soils (p < 0.05). The taxonomy assignment indicated that antibiotics accumulation in soils promoted the growth of 19 dominant genera, including several antibiotic-resistant or degrading bacteria, which however were generally not dominant in effluents. In addition, although the TN and NH 4 -N removals were reduced when antibiotic concentrations in soils increased, the available community data cannot strongly support the inhibition effect of antibiotics on nitrogen transformation. Further assessment found that some dominant genera in water samples and those enriched under the stress of antibiotics in soils tended to increase their abundances in the effluents of oyster shell-based CWs. [ABSTRACT FROM AUTHOR]

The fate of antibiotics and antibiotic resistance genes (ARGs) in constructed wetlands has received more concerns recently. This study aimed to assess the influence of hydraulic flow direction (down-flow or up-flow) and substrate type (brick rubble or oyster shell) on removal of antibiotics and ARGs from swine wastewater. For antibiotic removal, all of treatments can remove more than 84% of oxytetracycline and difloxacin during two stages of operation. Brick-based columns had stronger antibiotic removal capacity due to properties of brick, including large porosity and micropore size and 32% of Fe 2 O 3 . The surface soils tended to adsorb much more oxytetracycline than difloxacin, as was opposite to brick and oyster shell. For ARGs removal, the removal efficiencies of tetracycline-resistance genes ( tet ) and integrase gene of Class 1 integrons ranged from 33.2 to 99.1%, without significant difference among treatments (p > 0.05). However, most of ∑ tet relative abundances in effluents of up-flow treatments were higher than those in influents, which indicated a risk to release relatively more antibiotic-resistant bacteria in proportion to total bacteria into environment. Significantly correlated with antibiotic concentrations, ARGs relative abundances in surface soils increased as the time progressed for all the treatments. Our results demonstrate that antibiotic removal using constructed wetlands is greatly affected by substrate type, whereas variation of ARG relative abundances in effluents and soils are determined by hydraulic flow direction. [ABSTRACT FROM AUTHOR]