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In order to remove pollutants in domestic wastewater more completely, the anaerobic–anoxic–oxic (A2O)–membrane bioreactor (MBR)–biological aerated filter (BAF)–O3 combination process was studied. The ultrafiltration membrane was placed inside the A2O reactor to form an integrated reactor. The experimental water was sequentially degraded by A2O–MBR, BAF, and O3 reactor. The three operating parameters of hydraulic retention time (HRT), reflux ratio, and ozone contact time were optimized. The optimal conditions were found in the experiment: HRT was 10 h, reflux ratio was 200%, and ozone contact time was 15 min. Under these optimal conditions, the removal rates of chemical oxygen demand (COD), ammonia nitrogen, total nitrogen (TN), total organic carbon (TOC), UV254, and chroma were 96.00, 99.43, 82.46, 96.6, 93.20, and 79.00%, respectively. The effluent quality satisfied standard of Class IV surface water in China. The ultraviolet–visible and excitation-emission matrix spectra of water samples during the ozone oxidation were analyzed. It showed that the reaction was effective in removing chroma and humic acid-like substances in the wastewater. [ABSTRACT FROM AUTHOR]

Heavy metals (HMs) have the characteristics of high toxicity, long residual time, and difficult degradation, which pose a potential threat to aquatic ecosystems. The distribution and migration of HMs in different media can reflect their potential impact on aquatic ecosystem health. In this study, we analyzed the distribution characteristics of seven HMs (Zn, Cu, Cr, Ni, Hg, As, and Pb) in the water and sediment and five groups of organisms (fish, Crustacean, cephalopod, bivalvia, and gastropoda) in the sea ranching area of Haizhou Bay and explored the regularity of HM accumulation from water and sediments to organisms. The results showed that in the water, Zn and Hg had the smallest concentrations in the nearshore area, Cr had the lowest concentrations in the offshore area, and As, Cu, Pb, and Ni had the lowest concentrations in the central area. In the sediment, Hg had the smallest concentrations in the nearshore area and As, Pb, Cr, Cu, Ni, and Zn had the lowest concentrations in the offshore area; the average contents of seven heavy metals all meet the Class I standard of sediments in China. The concentrations of Cu and Zn in crustaceans were significantly higher than those in fishes (p < 0.05), and As showed a higher enrichment effect in cephalopods. Under the influence of feeding habits and habitat environment, the BAF value of benthic crustaceans and bivalvia accumulated HMs from sediments is high, and the BAF value of fish accumulated HMs from water and sediments is low. Overall, the concentration of HMs in water is high, and HMs in sediments are in good condition, crustaceans and bivalviaa have a strong ability to accumulate HMs from water and sediments, while fish are weak. Therefore, in order to ensure the safety of biological quality, it is necessary to focus on the discharge of heavy metal pollutants near the coast in the future. [ABSTRACT FROM AUTHOR]

Although China has been the main manufacturer and consumer of phthalate esters (PAEs), human health ambient water quality criteria (AWQCs) have not been proposed for these chemicals. In this study, the distribution and bioaccumulation of six PAEs (dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), bis (2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DnOP)) were investigated in 11 edible fish species collected from Poyang Lake, China. The results showed that the total concentrations of the six PAEs in the fish ranged between 118.63 and 819.84 μg/kg wet weight (mean of 327.50 ± 190.44 μg/kg). DMP, DEP, DBP, and DEHP were detected in all samples, of which DEHP and DBP were two of the most predominant phthalates, accounting for more than 90% of the total PAEs. The DEHP concentrations in fish with different habitat preferences were different, demersal species were significantly higher than pelagic species (p < 0.05). The mean natural logarithmic bioaccumulation factors (log BAFs) of PAEs increased with increasing lipophilicity of the substances, which yielded the following regression equation: log BAF (L/kg) = 0.103 log Kow + 2.158 (r2 = 0.940, p < 0.05, n = 4). Using this quantitative structure–activity relationship to calculate BAFs for the remaining undetected substances (BBP and DnOP) to derive AWQCs. According to the natural parameters, the human health AWQCs relating to PAE concentrations for water and fish consumption were derived as 9.4 × 103 (DMP), 5.0 × 102 (DEP), 4.2 × 101 (DBP), 1.1 (BBP), 8.6 × 10− 2 (DEHP), and 2.0 (DnOP) μg/L. Human health risk assessment indicated that the dietary intake of DEHP may exert a carcinogenic effect on residents of the Poyang Lake region. The results provide important input to assess the health risk posed by PAEs contaminated surface water. [ABSTRACT FROM AUTHOR]