Significant genomic introgression from grey junglefowl (Gallus sonneratii) to domestic chickens (Gallus gallus domesticus).

BACKGROUND: Chicken is one of the most numerous and widely distributed species around the world, and many studies support the multiple ancestral origins of domestic chickens. The research regarding the yellow skin phenotype in domestic chickens (regulated by BCO2) likely originating from the grey junglefowl serves as crucial evidence for demonstrating the multiple origins of chickens. However, beyond the BCO2 gene region, much remains unknown about the introgression from the grey junglefowl into domestic chickens. Therefore, in this study, based on whole-genome data of 149 samples including 4 species of wild junglefowls and 13 local domestic chicken breeds, we explored the introgression events from the grey junglefowl to domestic chickens. RESULTS: We successfully detected introgression regions besides BCO2, including two associated with growth trait (IGFBP2 and TKT), one associated with angiogenesis (TIMP3) and two members of the heat shock protein family (HSPB2 and CRYAB). Our findings suggest that the introgression from the grey junglefowl may impact the growth performance of chickens. Furthermore, we revealed introgression events from grey junglefowl at the BCO2 region in multiple domestic chicken breeds, indicating a phenomenon where the yellow skin phenotype likely underwent strong selection and was retained. Additionally, our haplotype analysis shed light on BCO2 introgression event from different sources of grey junglefowl into domestic chickens, possibly suggesting multiple genetic flows between the grey junglefowl and domestic chickens. CONCLUSIONS: In summary, our findings provide evidences of the grey junglefowl contributing to the genetic diversity of domestic chickens, laying the foundation for a deeper understanding of the genetic composition within domestic chickens, and offering new perspectives on the impact of introgression on domestic chickens.

The effect of nitrification inhibitors on the aerobic biodegradation of tetracycline antibiotics in swine wastewater.

The aerobic biotreatment process for the dual goals of antibiotic removal and ammonia retainment for the field-return-based treatment of swine wastewater was optimized by adding 2-chloro-6-trichloromethylpyridine (TCMP), commonly used as a nitrogen fertilizer synergist. The results show that the dosage of 5-10 mg/L TCMP daily effectively inhibited nitrification. The COD and tetracycline antibiotics (TCs) in the absence of TCMP was removed by 91% and 76%, and became 87% and 78% with 5 mg/L TCMP and 83% and 70% with 10 mg/L TCMP, respectively. The removal efficiency of four TCs generally followed a decreasing trend of chlortetracycline (CTC) > doxycycline (DC) > tetracycline (TC) > oxytetracycline (OTC). A dosage of 5 mg/L TCMP daily inhibited ammonia nitrification effectively and only slightly affected the removal of conventional organic pollutants and TCs. The contribution of volatilization and hydrolysis to the removal of TCs was negligible. The overall removal efficiency of four TCs in removal pathway experiments was 98%, 94%, 97%, and 96% for OTC, CTC, DC, and TC, of which 69%, 41%, 56%, and 62% was contributed by absorption, and 29%, 53%, 41%, and 34% was contributed by biodegradation, respectively. This study may have significant implications for the proper management of livestock wastewater intended to be used as fertilizers, which aims to reduce the exposure risk of antibiotics and preserve its nutrient value.

Genomic and transcriptomic analyses reveal genetic adaptation to cold conditions in the chickens.

Under the pressure of natural and artificial selection, domestic animals, including chickens, have evolved unique mechanisms of genetic adaptations such as high-altitude adaptation, hot and arid climate adaptation, and desert adaptation. Here, we investigated the genetic basis of cold tolerance in chicken by integrating whole-genome and transcriptome sequencing technologies. Genome-wide comparative analyses of 118 chickens living in different latitudes showed 46 genes and several pathways that may be involved in cold adaptation. The results of the functional enrichment analysis of differentially expressed genes proved the important role of metabolic pathways and immune-related pathways in cold tolerance in chickens. The subsequent integration of whole genome and transcriptome sequencing technology further identified six genes - dnah5 (dynein axonemal heavy chain 5), ptgs2 (prostaglandin-endoperoxide synthase 2), inhba (inhibin beta A subunit), irx2 (iroquois homeobox 2), ensgalg00000054917, and ensgalg00000046652 - requiring more detailed studies. In addition, we also discovered different allele frequency distributions of five SNPs (single nucleotide polymorphisms) within ptgs2 and nine SNPs within dnah5 in chickens in different latitudes, suggesting strong selective pressure of these two genes in chickens. We provide a novel insight into the genetic adaptation in chickens to cold environments, and provide a reference for evaluating and developing adaptive chicken breeds in cold environments.

[Spatiotemporal Distribution of Ammonia Emissions from Poultry Farming in the Yangtze River Delta Based on Online Monitoring Derived Local Emission Factors].

In order to obtain the ammonia emission level and space-time distribution characteristics of the poultry production industry in the Yangtze River Delta, an online high-resolution monitoring system was used to continuously monitor the atmospheric ammonia concentration in the breeding house and compost shed in a typical large-scale layer farm. By obtaining the ammonia emission level and emission factor during each growth stage, we established the localized ammonia emission inventory for the poultry production industry in the Yangtze River Delta. The results showed that the average daily ρ(NH3) in the breeding house and compost shed for spring, summer, autumn, and winter were (1.85±0.38), (4.58±0.33), (3.87±0.12), and (2.83±0.47) mg·m-3 and (2.04±0.50), (4.04±1.04), (2.51±0.67), and (1.55±0.16) mg·m-3 respectively. Ammonia emissions showed a significant daily hourly change trend. The highest hourly ammonia concentration in the layer house appeared from 13:00-14:00 in the afternoon, and the minimum appeared from 01:00-03:00 in the morning. The highest hourly ammonia concentration in the compost shed occurred between 16:00-19:00 in summer and autumn, whereas the diurnal changes in spring and winter were not significant. Hourly changes in ammonia emissions during the day were mainly affected by daily temperature, poultry activities, and manure management. Ammonia concentrations at different growth stages of laying hens showed significant differences. ρ (NH3) from young chickens, laying hens, and pre-eliminated chickens were (1.85±0.38), (2.83±0.47), and (1.61±0.32) mg·m-3, respectively. The ammonia emission rate from laying hens reached 1.53 times and 1.65 times that of young chickens and pre-eliminated chickens, respectively. Metabolism levels and feed intake at different growth stages were the main reasons for the differences in ammonia emissions. Ammonia emission factors for the layer house and compost shed in spring, summer, autumn, and winter were (0.13±0.02), (0.54±0.01), (0.39±0.01), and (0.17±0.01) g·(bird·d)-1 and (0.07±0.01), (0.17±0.02), (0.08±0.01), and (0.04±0.01) g·(bird·d)-1, respectively. Annual ammonia emission factors reached (0.11±0.06) kg·(bird·a)-1 and (0.03±0.02) kg·(bird·a)-1, respectively. Our results suggest that ambient temperature, ventilation mode, chicken house type, and manure removal frequency were the main influencing factors of ammonia emissions from poultry production. The uncertainty ranges of the ammonia emission coefficients reached±122%,±79%, and±74%, and±56%, respectively. Great uncertainties were generated when empirical emission factors were used for emission inventory establishment. Based on the results of online monitoring, model simulation, and literature analysis, we established an ammonia emission inventory for the poultry production industry within the Yangtze River Delta region by adopting the emission factors of (0.16±0.08) kg·(bird·a)-1. In 2019, the total ammonia emission from poultry production was (108.81±54.41) kt. In terms of spatial distribution, ammonia emission intensities in the northern regions were significantly higher than those in the southern parts. The ammonia emission intensities during summer were 3.38-3.56 times higher than those in spring and winter.

The role of nitrification inhibitors on the removal of antibiotics in livestock wastewater by aerobic biodegradation.

An optimized aerobic-based treatment method that effectively removes antibiotics and retains ammonia is urgently needed for the field-return-based management of livestock wastewater. Allylthiourea (ATU, used for BOD determination), and 2-chloro-6-trichloromethylpyridine (TCMP) and 3,4-dimethylpyrazole phosphate (DMPP) (commonly used as nitrogen fertilizer synergists) were separately added to sequencing batch reactors (SBRs), in order to investigate their effect on nitrification inhibition and pollutant removal for livestock wastewater treatment. The laboratory test shows that the daily addition of 43.8 mg/L ATU or 17.5 mg/L TCMP to SBRs effectively inhibited nitrification. Nitrification inhibition by DMPP seemed fluctuated and insufficient even various dosing strategies were attempted. The removal efficiency of antibiotics was reduced from 95% to 85% with the addition of ATU, while not significantly influenced by TCMP and DMPP. The COD removal efficiency was reduced by only 6%-10% with the addition of three inhibitors. The pilot study shows that nitrification inhibition efficiency reached 89% with the daily addition of 11.5 mg/L TCMP. The total removal efficiency of antibiotics remained over 93%. The laboratory and pilot studies consistently demonstrate that TCMP played a satisfactory nitrification inhibition role and had a negligible effect on antibiotic removal. The current work provides a novel insight for the proper field-return-based management of livestock wastewater, which achieves the dual goals of reducing the risk of antibiotic exposure and preserving its nutrient value as fertilizers.

Degradation of Polyamide Nanofiltration Membranes by Bromine: Changes of Physiochemical Properties and Filtration Performance.

The potential coexistence and interaction of bromine and polyamide membranes during membrane-based water treatment prompts us to investigate the effect of bromine on membrane performance. For fully aromatic polyamide membrane NF90 exposed under a mild bromination condition (10 mg/L), bromine incorporation resulted in more negatively charged (-13 vs -25 mV) and hydrophobic (55.2 vs 58.9°) surfaces and narrower pore channels (0.3 vs 0.29 nm). The permeabilities of water and neutral solutes were reduced by 64 and 69-87%, respectively, which was attributed to the decreased effective pore radius and hydrophilicity. NaCl permeability was reduced by 90% as a synergistic result of enhanced size exclusion and charge repulsion. The further exposure (100 and 500 mg/L bromine) resulted in a more hydrophobic surface (61.7 and 65.5°) and the minor further reduction for water and solute permeabilities (1-9%). Compared with chlorine, the different incorporation efficiency and properties (e.g., atomic size, hydrophilicity) of bromine resulted in opposite trends and/or different degrees for the variation of physicochemical properties and filtration performance of membranes. The bromine incorporation, the shift and disappearance of three characteristic bands, and the increased O/N ratio and calcium content indicated the degradation pathways of N-bromination and bromination-promoted hydrolysis under mild bromination conditions (480 mg/L·h). The further ring-bromination occurred after severe bromine exposure (4800-24,000 mg/L·h). The semi-aromatic polyamide membrane NF270 underwent a similar but less significant deteriorated filtration performance compared with NF90, which requires a different explanation.

Determination of estrogens and estrogen mimics by solid-phase extraction with liquid chromatography-tandem mass spectrometry.

An analytical method has been developed and validated for the determination of six estrogens and estrogen mimics, namely estriol (E3), bisphenol A (BPA), 17ß-estradiol (E2), estrone (E1), ethynyl estradiol (EE2) and dienestrol (DIE), with frequent occurrence in the natural environment. Solid phase extraction coupled with liquid chromatography tandem mass spectrometry (SPE-LC-MS/MS) using electrospray ionization (ESI) in a negative mode was applied to concentration, identification, and quantification of estrogens and estrogen mimics. The SPE conditions were optimized as the selection of C18 as cartridges and MeOH as an eluent, and the control of solution pH at 9.0. The method was validated by satisfactory recoveries (80-130%) and intra-day and inter-day precision (<18.4%, as relative standard deviation), and excellent linearity for calibration curves (R2 > 0.996). The limits of detection (LODs) for six target estrogenic compounds ranged between 2.5 and 19.2 ng/L. The effects of matrix background on the determination were evaluated in terms of LODs, LOQs, analyte recovery, and slopes of calibration curves in five different water matrices. Matrix effects by tap water were negligible. However, both matrix suppression and enhancement (i.e., E3, E1, DIE) were observed in surface water and wastewater. The positive correlation between LODs and TOC in various water matrices indicated the negative effect of organic pollutants on the method sensitivity. The sum of target estrogenic compounds in environmental samples were within 17-9462 ng/L.

Transformation kinetics and pathways of sulfamonomethoxine by UV/H2O2 in swine wastewater.

Sulfamonomethoxine (SMM), as one of the most predominant antibiotics in animal wastewater, is pending for effective control to minimize its environmental risks. Transformation kinetics and pathways of SMM by UV/H2O2 in swine wastewater were systematically investigated in this study. Direct UV photolysis (as a dominant role) and ∙OH oxidation contributed to SMM degradation in UV/H2O2 system. The less effective reaction rate of SMM in real wastewater than synthetic wastewater (0.1-0.17 vs. ∼0.2-1.5 min-1, despite higher H2O2 dosage and extended reaction time) resulted mainly from the abundant presence of conventional contaminants (indicated by COD, a notable competitor of SMM) in real wastewater. SMM degradation benefited from higher H2O2 dosage and neutral and weak alkaline conditions. However, the effect of initial SMM concentration on SMM degradation in synthetic and real wastewater showed opposite trends, owning to the different probability of SMM molecules to interact with UV and H2O2 in different matrices. Carbonate had an inhibitory effect on SMM degradation by scavenging ∙OH and pH-variation induced effect, while nitrate promoted SMM degradation by generating more ∙OH. The removal efficiency of SMM in real wastewater reached 91% under the reaction conditions of H2O2 of 10 mM, reaction time of 60 min, and pH 6.7-6.9. SMM degradation pathway was proposed as hydroxylation of benzene and pyrimidine rings, and secondary amine, and the subsequent cleavage of S-N bond.

The treatment of veterinary antibiotics in swine wastewater by biodegradation and Fenton-like oxidation.

Elevated concentrations and potential toxicities of antibiotics in swine wastewater prompt the exploration of effective treatment methods to minimize the amount of antibiotics released to the environment. This study examined the technical and economic feasibility of using combined biodegradation and advanced oxidation processes for swine wastewater treatment. The up-flow anaerobic sludge blanket (UASB) reactor was mainly responsible for conventional organic pollutant removal (i.e., a COD removal rate of 75%). The subsequent sequencing batch reactor (SBR) under a short sludge retention time (SRT) of 3 days removed the biodegradable antibiotics by >95%, and hindered the nitrification process which retained NH4+-N and reduced operational cost (since the treated wastewater was intended to be used as a farm fertilizer). The subsequent Fenton-like oxidation (with the aid of citric acid) achieved an average antibiotic removal efficiency of 74% under optimal reaction conditions: H2O2 dosage of 2.9 mM, [Fe2+]: [H2O2] = 1:3, [CA]: [Fe2+] = 1:1, pH 6.0, reaction time of 120 min. The superior treatment efficiency of Fenton-like compared to the conventional Fenton (74% vs 5%) under nearly neutral conditions was attributed to the chelating role of citric acid with Fe2+/Fe3+, leading to the enhanced Fe2+/Fe3+ solubility and therefore the promotion of ∙OH formation. This hybrid process of anaerobic and aerobic biodegradation and Fenton-like oxidation should be suitable and cost-effective for the treatment of wastewater with abundant conventional pollutants and persistent emerging trace contaminants.

Environmental occurrence and risk assessment of haloacetic acids in swimming pool water and drinking water.

A prevalent group of disinfection by-products (DBPs), i.e., haloacetic acids (HAAs), have raised significant public concern due to their high frequency of occurrence, considerable concentrations and potent toxicity. This study investigated the environmental occurrence of HAAs and the corresponding predicted human exposure to two important water matrices where humans are frequently and long-term exposed, i.e., swimming pool waters (SPWs) and drinking waters (DWs), in Shanghai, China. The sum of five HAAs in SPWs was 241 µg L-1 on average (dominated by dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA)), four times as much as its maximum contaminant level (MCL) regulated by the Environmental Protection Agency (EPA) in DWs. The maximum HAA concentration in DWs was 35 µg L-1, with chloroacetic acid (CAA) as the most dominant compound. The higher concentrations (reflected by total organic carbon (TOC), dissolved organic carbon (DOC), and UV254) and more categories (body fluids and personal care products in addition to natural organic matter) of organic contaminants and the higher chlorine in SPWs should be responsible for the differentiated HAA yield and speciation. The qualification rates of samples have been evaluated. The power function models correlating HAAs with multiple water quality parameters were developed with correlation coefficients of 0.614 and 0.798 for SPWs and DWs respectively. These models may provide the preliminary insights on how to minimize HAA formation by grasping the relative importance of each parameter and how to build the framework to predict HAA formation in untreated source water or SPWs subjected to chlorination. The predicted carcinogenic and non-carcinogenic risks of humans exposed to SPWs and DWs with HAAs were within the acceptable levels.

A hybrid process of Fe-based catalytic ozonation and biodegradation for the treatment of industrial wastewater reverse osmosis concentrate.

This work investigated the feasibility of a hybrid process consisting of catalytic ozonation and biodegradation (i.e., sequencing batch reactor, SBR) for the treatment of the industrial-based reverse osmosis concentrate (ROC) with specific characteristics of high levels of total dissolved solids (TDS) and refractory pollutants. The Fe-based homogeneous and heterogeneous catalytic ozonation was in parallel investigated and compared in terms of contaminant removal efficiency and biodegradability variation. The Fe-based heterogeneous catalyst carried the higher potential to improve the biodegradability of ROC (i.e., 0.32 v. s. 0.27 for B/C, the ratio between BOD5 and COD) although its direct COD removal efficiency was inferior to the homogeneous one (i.e., 49% v. s. 59% after 25 min' reaction). The ROC pretreated by the Fe-based heterogeneous catalytic ozonation for 5 min was further treated by biodegradation. After the hybrid treatment, the COD concentration reached ∼40 mg/L meeting with the discharge standard (GB, 18918-2002), under the optimal reaction conditions of 2.0 L/min ozone flow rate for catalytic ozonation and 120 min' aeration for biodegradation. The solution pH should not be adjusted by taking both the treatment efficiency and operating cost into consideration. The treatment cost of the hybrid process was estimated to be 0.15 USD/m3. This work could provide a feasible and economic option for the proper management of the industrial-based ROC and should be of interest to the application fields.

Removal of veterinary antibiotics from swine wastewater using anaerobic and aerobic biodegradation.

High amounts of antibiotics, used in animal farms for the prevention of diseases, are released back into the natural environment with a possible risk of chronic toxicity to other organisms and the development of antibiotic-resistant genes. The antibiotics, including sulfonamides and ß-lactams, detected in swine wastewater were between 99.2 and 339.3 µg/L. The typical on-site swine wastewater treatment process turned out to be inadequate, reflected by the high conventional contaminant and antibiotic residuals even under a long hydraulic residence time (HRT, around 2-3 months). The lab-scale combined anaerobic and aerobic biological process showed that anaerobic digestion was mainly responsible for chemical oxygen demand (COD) reduction and aerobic biodegradation contributed significantly to antibiotic removal, with overall removal efficiencies of 95% for COD and 92% for antibiotics under a short HRT of 3.3 days. The removal of selected antibiotics could be a combined result of biodegradation, the balance between adsorption and desorption, and the transformation between antibiotic metabolites and their parent antibiotics. The current work provides valuable insights into the appropriate selection and optimisation of biological processes for the treatment of typical wastewater with high COD and trace antibiotics.

The role of active manganese species and free radicals in permanganate/bisulfite process.

Bisulfite-activated permanganate (PM/BS) process has shown extremely great potential for the rapid degradation of organic contaminants while the active oxidants involved in this process have been under disputation. In this work, the active oxidants in PM/BS process were re-identified and the contributions of different active oxidants to the degradation of various organic contaminants were investigated with a competition kinetics method. Many lines of evidence indicated that both radical species, including hydroxyl radical (HO) and sulfate radical (SO4-), and reactive manganese species (RMnS), including Mn(VI), Mn(V), and possible Mn(III), contribute to the degradation of contaminants in PM/BS process. SO4- contributed much more than HO to the degradation of all contaminants of interest except nitrobenzene in PM/BS process. RMnS were very selective and showed high reactivity to phenolic and sulfoxide compounds as well as carbamazepine. With the increase of initial pH and the [bisulfite]/[permanganate] molar ratio, a mechanistic changeover from RMnS to radicals occurred during phenol degradation in PM/BS process. The generation of RMnS and radical species, especially SO4-, could be well explained by the proposed mechanism consisting of radical chain reactions and manganese reduction reactions via both electron transfer and oxygen transfer steps.

Ferrous ion mitigates the negative effects of humic acid on removal of 4-nitrophenol by zerovalent iron.

In this study, Fe2+ addition was employed to overcome the negative effects of humic acid (HA) on contaminant removal by zerovalent iron (ZVI), and its feasibility to improve electron efficiency of ZVI was also tested. HA at high concentrations suppressed the removal of 4-nitrophenol (4-NP) by ZVI, while the addition of 0.25-1.0 mM Fe2+ could greatly mitigate this inhibitory effect and enhance 4-NP reduction. Specifically, with a mixed-order model, global fitting results showed that the addition of Fe2+ increased the rate constant from 0.124 × 10-2-0.219 × 10-2 mM/min to 0.227 × 10-2-0.417 × 10-2 mM/min and shortened lag period from 19.7-47.9 min to 8.0-15.2 min for 4-NP removal. The mechanistic investigation revealed this trend could be explained by the following aspects: i) Fe2+ can facilitate the generation of Fe(II)-containing oxides, which can act as an electron mediator or direct electron donor for 4-NP reduction; ii) the presence of Fe2+ could lead to aggregation of HA particles and accordingly reduced its coverage on ZVI surface. But the results of respike experiments indicate that Fe2+ addition did not show remarkable effect on the electron efficiency of 4-NP by ZVI, which should be associated with that Fe2+ was not able to favor the enrichment of 4-NP on ZVI surface.

Role of pyrophosphate on the degradation of sulfamethoxazole by permanganate combined with different reductants: Positive or negative.

Activating permanganate with reductants has gained increasing attention recently for efficient organic contaminants abatement via reactive intermediate Mn species. However, few studies have been conducted to explore the role of pyrophosphate (PP), a typical complexing agent for intermediate Mn species, in activated permanganate systems. In this study, taking sulfamethoxazole (SMX) as a probe compound, the influences of PP on SMX degradation by permanganate/thiosulfate and permanganate/hydroxylamine were extensively studied. It was found that both thiosulfate and hydroxylamine were able to activate permanganate for oxidation of SMX in the absence of PP. However, upon the introduction of PP, opposite effects were observed in the two systems where PP further improved the activation of permanganate by thiosulfate but dampened the performance of permanganate/hydroxylamine markedly. For permanganate/hydroxylamine system, MnO2 was determined to be the only reactive oxidative species accounting for SMX degradation in the absence of PP, and its generation could be completely inhibited by PP. While in permanganate/thiosulfate system, both Mn(V) and MnO2 were responsible for SMX oxidation, and the introduction of PP could strengthen the oxidative ability of Mn(V). These results could shed some insights on the suitability of applying PP to explore the kinetics and mechanisms of manganese involved redox reactions. PRACTITIONER POINTS: Both Na2 S2 O3 and NH2 OH·HCl can activate KMnO4 for SMX removal without PP. MnO2 is the reactive oxidative species involved in KMnO4 /NH2 OH·HCl system. Mn(V) and MnO2 account for the SMX oxidation by KMnO4 /Na2 S2 O3 system. PP could inhibit the formation of MnO2 but enhance the oxidative ability of Mn(V).

Treatment of triethyl phosphate wastewater by Fenton oxidation and aerobic biodegradation.

The conventional (i.e., aerobic biodegradation) and advanced (i.e., Fenton oxidation) treatment methods with implementation potentials were in parallel investigated for the treatment of industrial wastewater rich in organic phosphorus (Org.-P, dominated by triethyl phosphate (TEP)). Fenton effectively reduced Org.-P from 58 to 5 mg/L under the optimal reaction conditions of 20 mM H2O2, 14 mM Fe2+, pH 3.0, 120 mins' reaction time and the continuous dosing method (N = 4), following the first order kinetic model with a reaction rate constant of 0.07 min-1. Nevertheless, the pretreatment prior to Fenton reaction (e.g., desalination) is recommended since high salinity significantly hindered TEP degradation, possibly due to the formation of Fe-Cl complexation and its scavenging effect to ∙OH. The Org.-P mineralization rate of ~98% was achieved by aerobic biodegradation. The excellent performance was maintained up to a salinity of 4.6% (w/w), higher than which the mineralization was seriously deteriorated. The high salinity could inhibit the microbial growth. This property might be responsible for the insufficient Org.-P removal during the on-site wastewater biological treatment. The Org.-P and COD concentrations were 6 and 405 mg/L respectively after the realistic wastewater treatment by biodegradation and coagulation, which meets with the municipal sewer discharge standard (GB/T 31962-2015).

Regulation, formation, exposure, and treatment of disinfection by-products (DBPs) in swimming pool waters: A critical review.

The microbial safety of swimming pool waters (SPWs) becomes increasingly important with the popularity of swimming activities. Disinfection aiming at killing microbes in SPWs produces disinfection by-products (DBPs), which has attracted considerable public attentions due to their high frequency of occurrence, considerable concentrations and potent toxicity. We reviewed the latest research progress within the last four decades on the regulation, formation, exposure, and treatment of DBPs in the context of SPWs. This paper specifically discussed DBP regulations in different regions, formation mechanisms related with disinfectants, precursors and other various conditions, human exposure assessment reflected by biomarkers or epidemiological evidence, and the control and treatment of DBPs. Compared to drinking water with natural organic matter as the main organic precursor of DBPs, the additional human inputs (i.e., body fluids and personal care products) to SPWs make the water matrix more complicated and lead to the formation of more types and greater concentrations of DBPs. Dermal absorption and inhalation are two main exposure pathways for trihalomethanes while ingestion for haloacetic acids, reflected by DBP occurrence in human matrices including exhaled air, urine, blood, and plasma. Studies show that membrane filtration, advanced oxidation processes, biodegradation, thermal degradation, chemical reduction, and some hybrid processes are the potential DBP treatment technologies. The removal efficiency, possible mechanisms and future challenges of these DBP treatment methods are summarized in this review, which may facilitate their full-scale applications and provide potential directions for further research extension.

Removal of trace level amounts of twelve sulfonamides from drinking water by UV-activated peroxymonosulfate.

Trace levels of residual antibiotics in drinking water may threaten public health and become a serious problem in modern society. In this work, we investigated the degradation of twelve sulfonamides (SAs) at environmentally relevant trace level concentrations by three different methods: ultraviolet (UV) photolysis, peroxymonosulfate (PMS) oxidation, and UV-activated PMS (UV/PMS). Sulfaguanidine, sulfadiazine, sulfamerazine, sulfamethazine, sulfathiazole, sulfamethoxydiazine, and sulfadimethoxine were be effectively removed by direct UV photolysis and PMS oxidation. However, sulfanilamide, sulfamethizole, sulfamethoxazole, sulfisoxazole, and sulfachloropyridazine were not completely degraded, despite prolonging the UV irradiation time to 30min or increasing the PMS concentration to 5.0mg·L-1. UV/PMS provided more thorough elimination of SAs, as demonstrated by the complete removal of 200ng·L-1 of all SAs within 5min at an initial PMS concentration of 1.0mg·L-1. UV/PMS promoted SA decomposition more efficiently than UV photolysis or PMS oxidation alone. Bicarbonate concentration and pH had a negligible effect on SA degradation by UV/PMS. However, humic acid retarded the process. Removal of 200ng·L-1 of each SA from a sample of sand-filtered effluent from a drinking water treatment plant (DWTPs) was quickly and completely achieved by UV/PMS. Meanwhile, about 41% of the total organic carbon (TOC) was eliminated. Scavenging experiments showed that sulfate radical (SO4-) was the predominant species involved in the degradation. It is concluded that UV/PMS is a rapid and efficient method for removing trace-level SAs from drinking water.

[Distribution Characteristics and Health Risk Assessment of Thirteen Sulfonamides Antibiotics in a Drinking Water Source in East China].

Trace levels of residual antibiotics in drinking water sources may threaten public health and becomes a serious issue in modern society. Occurrence and distribution of 13 sulfonamides antibiotics in a drinking water source in East China were investigated using solid phase extraction-high performance liquid chromatography-tandem mass spectrometry. The results revealed that all 13 sulfonamides were detected with the total concentrations ranging from 10.5 ng·L-1 to 238.5 ng·L-1. Sulfamethoxazole (SMX) and sulfonamide (SAM) presented the 100% detected frequency, and the maximum concentrations reached 107.0 ng·L-1 and 43.1 ng·L-1, respectively. Sulfonamides contamination levels in the inlet were relatively higher than those in the outlet. The concentration of SMX was substantially unchanged in different positions of drinking water source. Seasonal variation of sulfonamide concentration showed that the concentrations were higher in winter and spring compared with those in summer and autumn. The range of total sulfonamides concentration detected in winter and spring was from 110.8 ng·L-1 to 117.9 ng·L-1, which was 3.6-3.8 times higher than those in summer and autumn. Human health risk characterization of residual sulfonamides in drinking water source was based on the assessment of risk quotients (RQs) for which different life stages were taken into account. The results showed that no sulfonamides had a RQs higher than 1. Trimethoprim (TMP) was the most risky antibiotic to the 0-3 months old infants with RQs reaching 0.001. Although the sulfonamides detected in the drinking water source do not pose any risk to the peoples' health, the implication of long-time exposure and comprehensive risk still deserve attention.

Regeneration and reuse of iron catalyst for Fenton-like reactions.

Fenton and Fenton-like reactions employed for oxidative treatment of a typical industrial wastewater generate a large amount of ferric hydroxide sludge which has to be properly disposed at a high cost. This paper presents a simple and cost-effective method for recovering the iron catalyst from the iron hydroxide sludge for oxidative treatment of industrial wastewaters. The sludge was dewatered, dried and baked at 350-400 degrees C for 20-30 min; the residual solids were dissolved in sulfuric acid to form the reusable catalyst for Fenton and Fenton-like reactions. The recovered catalyst was highly effective for the oxidative pretreatment of a fine chemical wastewater to improve its biodegradability; the resulting COD removal and BOD(5)/COD ratio of the treated stream remained nearly unchanged during the time period when the regenerated catalyst was reused six times. The simple and effective catalyst regeneration method will make Fenton and Fenton-like oxidation a more cost-effective wastewater treatment alternative.