Sewage treatment plants (STPs) and pharmaceutical manufactories (PMFs) are recognized as important reservoirs for aquatic pollution with antibiotics. Although the occurrence of multiple classes of ...antibiotics has been mostly reported for STPs and PMFs, knowledge on the effects of wastewater treatment processes on the removal of antibiotics is not well documented. In this study, wastewaters were collected from different treatment points of two STPs and two PMFs in eastern China. Thirty-seven antibiotics within the four classes of fluoroquinolones (FQs), macrolides (MACs), sulfonamides (SAs) and tetracyclines (TCs) were analyzed. Among the investigated antibiotics, 19–33 out of 37 target compounds were detected at least once in the STPs wastewaters ranging from low ng/L to approximately 12.7 μ/L. In the wastewater samples collected from PMFs, up to 34 antibiotics were present with detection frequencies up to 100%, showing generally higher concentrations (up to 19.0 μ/L) than those at the STPs. FQs and SAs were the dominant antibiotic families, which accounted for more than 90% of the total antibiotic concentration in the wastewaters. Moreover, the removal of antibiotics by anaerobic-anoxic-oxic (A2O), membrane bioreactor (MBR) and conventional activated sludge (CAS) systems was evaluated. The MBR system exhibited the best performance, mainly due to the processes of biodegradation and sorption during biological treatments. Notably, several SAs (SMP, SMZ) and FQs (CIN, ENO) antibiotics were consistently detected at concentration levels of μ/L in the effluent samples. The culturable antibiotic-resistance tests and risk assessment indicated that the antibiotic-contaminated effluents would facilitate the development of resistant bacteria and pose high toxicity to non-target organisms in the aquatic environment. Overall, the findings suggested an urgent need for improving the wastewater treatment technologies for simultaneous removal of different classes of antibiotics.
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•Thirty-seven antibiotics in four classes were studied in sewage and pharmaceutical wastewaters.•Raw and treated wastewaters were mainly contaminated by sulfonamides and fluoroquinolones.•Combination of AO and MBR treatments contributed to the best antibiotic removal of MBR system.•The final effluents demonstrated antibiotic resistance property and ecotoxicity.•Pharmaceutical manufactories are more serious sources of antibiotic pollution in waters.
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According to the existing research results, this paper reviews the influent and effluent concentrations, migration and transformation, and influencing factors of quinolone antibiotics ...in sewage treatment plants (STPs) with activated sludge treatment processes. Animal breeding and slaughtering wastewater, pharmaceutical wastewater and medical and domestic sewage may be the main sources of quinolone antibiotics. The compounds and concentrations of quinolone antibiotics in influents and effluents around the world are quite different, which is generally due to the difference in social and environmental factors in different regions, and the different treatment processes and operating parameters adopted. The migration and transformation of quinolone antibiotics is usually the result of the synergistic effect of sludge adsorption, biodegradation and photolysis. Sludge adsorption based on electrostatic interaction, hydrophobic forces and other mechanisms is the dominant route to remove quinolone antibiotics, but it does not reduce the total amount of the target antibiotics. An appropriate selection of conditions and control of process variables are beneficial to improve the removal of quinolone antibiotics by biodegradation with co-metabolism. Sources control, treatment processes improvement, fate understanding and prediction, monitoring strategies and risks assessment are potential options for improving the elimination and controlling the pollution of quinolone antibiotics in the future.
Progress toward the sanitation component of Millennium Development Goal (MDG) Target 7c was reassessed to account for the need to protect communities and the wider population from exposure to human ...excreta. We classified connections to sewerage as "improved sanitation" only if the sewage was treated before discharge to the environment. Sewerage connection data was available for 167 countries in 2010; of these, 77 had published data on sewage treatment prevalence. We developed an empirical model to estimate sewage treatment prevalence for 47 additional countries. We estimate that in 2010, 40% of the global population (2.8 billion people) used improved sanitation, as opposed to the estimate of 62% (4.3 billion people) from the WHO/UNICEF Joint Monitoring Programme (JMP), and that 4.1 billion people lacked access to an improved sanitation facility. Redefining sewerage-without-treatment as "unimproved sanitation" in MDG monitoring would raise the 1990 baseline population using unimproved sanitation from 53% to 64% and the corresponding 2015 target from 27% to 32%. At the current rate of progress, we estimate a shortfall of 28 percentage points (1.9 billion people) in 2010 and a projected 27 percentage point shortfall in 2015.
Primary microplastics are mostly produced as part of the daily plastic product use. The emission process is often invisible but poses potential ecological hazards. Thus, primary microplastics deserve ...public attention. Due to China's huge population base and its rapid economic development, primary microplastics emissions are of both regional and global significance. This study is the first to establish the emission inventory of primary microplastics in mainland China. It was estimated that the primary microplastic waste from mainland China amounts to 737.29 Gg, and one-sixth of this amount entered the aquatic environment in 2015. The highest proportion of this waste was attributable to tire dust and synthetic fiber, accounting for 53.91% and 28.77% of the total respectively, in mainland China. The primary microplastics emissions mainly depend on the population, followed by the level of economic development. It was roughly estimated that 538 g of microplastics is produced by each person in China. At the grid scale, the spatial difference in the total primary microplastics emissions in mainland China primarily depends on the population density distribution and transportation network. We studied the entire life cycle of several sources of microplastics, from production to discharge into the aquatic environment. We suggested different control measures under different nodes. Increasing microplastics treatment in sewage treatment plants should be a short-term viable way to achieve some measure of reduction in their entry to the environment in mainland China. Our research can not only raise public awareness about primary microplastics, but can also guide the development of environmental policies to reduce plastic pollution.
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•We first summarized the emission characteristics of primary microplastics.•It was estimated that 737.29 Gg primary MP are emitted in mainland China in 2015.•One-sixth of emitted primary MP enters the aquatic environment.•The emission of primary MP depends on the population, followed by the transportation network.•Increasing treatment of MP in STP is a realistic and effective measure to reduce pollution by them.
Aim of this study was to provide an up-to-date assessment of the antibiotics contaminating the aqueous environment in Italy, for a better understanding of risks for the ecosystem and human health. ...Antibiotics were first listed in order of their theoretical environmental loads, then were measured in wastewater of some sewage treatment plants (STPs) and in rivers in Italy. Macrolides, particularly clarithromycin and spiramycin, and quinolones, particularly ciprofloxacin and
l-floxacin/ofloxacin, were the most abundant antibiotics in untreated wastewater. Several of them were not removed in STPs and still remained in the treated wastewater, and a total estimate of 7–14
tons of active principles were discharged annually into the aqueous environment in Italy through this route. Results of the analysis of rivers in northern Italy agreed with these figures, with an average load of 5
kg/day, or about 1.8
tons/year, of antibiotics flowing in the River Po, at sampling sites covering a basin comprising about one-fifth of the Italian population. In conclusion, antibiotics, particularly macrolides and quinolones, are widespread environmental contaminants, and urban STPs are confirmed a major source of the contamination.
The presence of antibiotics in the aqueous environment can alter the water microbiome, inducing antimicrobial resistance genes. Hence, the occurrence of 18 antibiotics belonging to sulfonamides, ...fluoroquinolones, tetracyclines, phenicols, and macrolides classes were investigated in surface water, groundwater, and sewage treatment plants in Chennai city and the suburbs. Fluoroquinolones had the maximum detection frequency in both influent and effluent samples of urban and suburban STPs, with ofloxacin and ciprofloxacin showing the highest influent concentrations. Erythromycin was the predominant antibiotic in surface water samples with an average concentration of 194.4 ng/L. All the detected antibiotic concentrations were higher in the Buckingham Canal compared to those in Adyar and Cooum rivers, possibly due to direct sewer outfalls in the canal. In groundwater samples, ciprofloxacin showed the highest levels with an average of 20.48 ng/L and the concentrations were comparable to those of surface water. The average sulfamethazine concentration in groundwater (5.2 ng/L) was found to be slightly higher than that of the surface water and much higher than the STP influent concentrations. High levels of ciprofloxacin and sulfamethazine in groundwater may be because of their high solubility and wide use. Moreover, erythromycin was completely removed after treatment in urban STPs; FQs showed relatively lesser removal efficiency (2.4–54%) in urban STPs and (8–44%) in suburban STP. Tetracyclines and phenicols were not detected in any of the samples. Ciprofloxacin and azithromycin in surface water pose a high risk in terms of estimated antibiotic resistance. This study revealed that the measured surface water concentration of antibiotics were 500 times higher for some compounds than the predicted calculated concentrations from STP effluents. Therefore, we suspect the direct sewage outlets or open drains might play an important role in contaminating surface water bodies in Chennai city.
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•Ofloxacin showed the highest concentrations in influents and effluents of STPs in Chennai.•Erythromycin and roxithromycin were completely removed after sewage treatment.•Surface water antibiotic levels were higher than those estimated from STP effluents.•Ciprofloxacin and azithromycin pose a high risk in terms of antibiotic resistance.
Over the recent years, ever-increasing population growth and higher wastewater production has been a challenge for decentralized wastewater treatment plants (WWTPs). In addition, sludge treatment due ...to high cost for equipment and place make authorities to find a sustainable approach in both of economical and technical perspectives. One of the proposed solutions is transferring the sludge produced from decentralized WWTP to centralized WWTP. However, the appropriate proportional ratio of raw sludge to raw sewage is a challenge, otherwise, it make anaerobic conditions and sewage rotting along the sewer network based on permissible limit of dihydrogen sulfide (H
S) gas (5 ppm). In the present study, seven reactors with different ratios of sludge to raw sewage (0, 15, 20, 25, 50, 75, 100) were used to stimulate the feasibility of transferring Shahrake Gharb WWTP sludge along the wastewater transfer pipe to the centralized sewage treatment south Tehran WWTP plant in Tehran, Iran. The septic situation and H
S emission of different reactors within 7 h (Time to reach the compound in the south treatment plant) was analyzed by gas meter. The results indicated that the optimum ratio of sludge to raw sewage was 15% without H
S production during 7 h. In addition, due to the high volume of sludge produced by the Shahrake Gharb WWTP, the optimal ratio of lime to total solids (TS) in sludge (gr/gr) (0.6) increased the sludge loading rate from 15 to 30% without any H
S emission during the stimulation study period. Therefore, the lime stabilization and transfer of sludge from a decentralized WWTP to a centralized WWTP is a feasible way to manage the sludge and enhance the treatment capacity in local WWTP.
Class 1 integrons and gene cassettes containing antibiotic resistance genes (ARGs) in five different sewage treatment plants (STPs) were characterized and quantified using polymerase chain reaction ...(PCR), sequencing, and quantitative real-time PCR (qRT-PCR) in this study. Class 1 integronase gene (intI1) was found commonly occurring in all of activated sludge samples from the five STPs, as well as in influent and effluent of two STPs at Hong Kong. One hundred and nine lactose-fermenting Enterobacteriaceae (LFE) strains were isolated from activated sludge of Shatin STP. Among them, 36 strains (33.0%) were found to carry class 1 integrons. PCR assays showed that 11 of the 36 intI1-carrying isolates harbored a common type of gene cassette array of about 1,600 bps, as well as the static genes (sulI and qacEΔ1) on class 1 integrons. This gene cassette array was found phylogenetically close to antibiotic resistance genes dfr17 and aadA5, encoding dihydrofolate reductase conferring resistance to trimethoprim and adenylyltransferase conferring resistance to spectinomycin/streptomycin, respectively. Antimicrobial susceptibility analysis demonstrated that all the 11 LFEs carrying gene cassette were multi-resistant, especially having common resistance to trimethoprim and streptomycin. qRT-PCR assay showed that genes copies of both class 1 integron and the gene cassette varied significantly among the activated sludge sampled from different STPs, at different time points or different treatment steps. More than 90% of class 1 integrons and the gene cassette were removed by activated sludge processes in two STPs, while the disinfection process removed 94% integron and 77% gene cassette in one STP.
Phosphorus recovery from sewage sludge as secondary raw materials or as a direct P-rich fertiliser is one of the top frontrunner solutions to tackle Phosphorus (P) scarcity and depletion. However, ...the efficiency of this P recovery process greatly depends on its phosphorus dissolution potential, which in return relies on the phosphorus speciation in the sewage sludge. This article investigates the potential correlation between P speciation in sewage sludge and the iron-based P removal technologies used in sewage treatment plants (STP) through an innovative sequential extraction method based on the SEDEX method that distinguishes quantitatively between ferrous bound phosphate and ferric bound phosphate. XRD and SEM-EDX were also used to characterise P and Fe species in the studied sludge qualitatively. Principal component analysis showed that the sludge characterised by P bound to ferric iron (as the dominant P fraction) are mostly correlated with sludge produced from the CPR process (chemical phosphorus removal) and primary sludge. Moreover, sludge with a non-negligible amount of P bound to ferrous iron were correlated with sludge from the mixed EBPR-CPR process (Enhanced Biological P Removal assisted with CPR). However, Vivianite was only found in CPR sludge with Fe/P molar ratio higher than 0.6.
