Evaluation of spatial distribution and accumulation of novel brominated flame retardants,HBCD and PBDEs in an Italian subalpine lake using zebra mussel (Dreissena polymorpha)

Because of the reduction in the use of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD), novel brominated flame retardants (NBFRs), including 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), decabromodiphenyl ethane (DBDPE), hexabromobenzene (HBB), and pentabromoethylbenzene (PBEB), started to be marketed as alternatives to the banned formulations. In this study, the spatial distribution and accumulation of NBFRs, PBDEs, and HBCD in the biota have been investigated in the littoral compartment of a large and deep subalpine lake (Lake Maggiore, Northern Italy), using zebra mussel Dreissena polymorpha and roach (Rutilus rutilus) as bioindicators. To our knowledge, this is the first study reporting the contamination of NBFRs in the freshwater invertebrate D. polymorpha. Contamination of zebra mussel due to PBEB, HBB, and BTBPE was low, ranging from 0.9 to 2.9 ng/g lipid weight, from 1.1 to 2.9 ng/g l.w., and from 3.5 to 9.5 ng/g l.w., respectively. PBEB and BTBPE in roach were always below the detection limit, while the contamination of HBB ranged from < limits of detection (LOD) to 1.74 ng/g l.w., indicating a weak contamination. DBDPE was < LOD in all the considered biological samples. Finally, HBCD was detected in all organic tissues with mean concentrations up to 74.4 ng/g l.w. PBDE results, supported by principal component analysis elaboration, suggested a possible contamination due to the congeners composing the penta- and deca-BDE technical formulations, which are present in the Lake Maggiore basin. The biomagnification factor values showed that tetra- and penta-BDE biomagnified, while octa-, nona-, and deca-BDE were still bioavailable and detectable in the fish muscles, but they do not biomagnified. Considering the other BFRs, only HBCD showed a moderate biomagnification potential.     

Occurrence of alternative flame retardants in indoor dust from New Zealand: indoor sources and human exposure assessment

Due to worldwide restrictions on polybrominated diphenyl ethers (PBDEs), the demand for alternative flame retardants (AFRs), such as organophosphate flame retardants (OPFRs), novel brominated FRs (NBFRs) and hexabromocyclododecanes (HBCDs), has recently increased. Little is known about human exposure to NBFRs and OPFRs and that their levels in dust have been scarcely evaluated worldwide. To increase the knowledge regarding these chemicals, we measured concentrations of five major NBFRs, ten OPFRs and three HBCD isomers in indoor dust from New Zealand homes. Dust samples were taken from living room floors (n=34) and from mattresses of the same houses (n=16). Concentrations (ngg(-1)) of NBFRs were: 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) (<2-175), decabromodiphenyl ethane (DBDPE) (<5-1430), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB) (<2-2285) and bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH) (<2-640). For OPFRs, concentrations (ngg(-1)) ranged between: tri-ethyl-phosphate (TEP) (<10-235), tri-n-butyl-phosphate (TnBP) (<20-7545), tris-(2-chloroethyl)-phosphate (TCEP) (<20-7605), tris-(1-chloro-2-propyl) phosphate (TCPP) (20-7615), tri-(2-butoxyethyl)-phosphate (TBEP) (50-27325), tris-(2,3-dichloropropyl)-phosphate (TDCPP) (20-16560), tri-phenyl-phosphate (TPhP) (20-35190), and tri-cresyl-phosphate (TCP) (<50-3760). HBCD concentrations fell in the range <2-4100ngg(-1). BTBPE, DBDPE, TBPH, TBEP, and TnBP showed significant positive correlation (p<0.05) between their concentrations in mattresses and the corresponding floor dust (n=16). These data were used to derive a range of plausible exposure scenarios. Although the estimated exposure is well below the corresponding reference doses (RfDs), caution is needed given the likely future increase in use of these FRs and the currently unknown contribution to human exposure by other pathways such as inhalation and diet.     

"Novel" brominated flame retardants in Belgian and UK indoor dust: implications for human exposure

Concentrations of several “novel” brominated flame retardants (NBFRs) are reported in indoor dust samples from Belgian houses (n = 39) and offices (n = 6) and from day-care centers and schools in the West Midlands of the UK (n = 36). Using a GC-ECNI/MS method, the following NBFRs were quantified: decabromodiphenyl ethane (DBDPE) (range <20-2470 ng g⁻¹), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) (range <0.5-1740 ng g⁻¹), tetrabromobisphenol A-bis(2,3-dibromopropylether) (TBBPA-DBPE) (range <20-9960 ng g⁻¹), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB) (range <2-436 ng g⁻¹) and bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH) (range <2-6175 ng g⁻¹). Hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO), another NBFR, was below the detection limit of 2 ng g⁻¹ dust in all dust samples. No correlation was detected between concentrations of NBFRs and PBDEs. The ratio of TBB:TBPH in the dust samples ranged from 0.01 to 4.77 (average 0.42), compared to the ratio present in the commercial flame retardant product FM 550 (TBB:TBPH = 4:1). Furthermore, no correlation was detected between concentrations in dust of TBB and TBPH. This may suggest different sources of these NBFRs, or similar sources but compound-specific differences in their indoor fate and transport. Exposure via dust ingestion was estimated for both adults and toddlers under low-end (5th percentile), typical (median), and high-end (95th percentile concentrations) scenarios. These were calculated assuming 100% absorption of intake dust and using mean dust ingestion (adults = 20 mg d⁻¹; for toddlers = 50 mg d⁻¹) and high dust ingestion (adults = 50 mg d⁻¹; for toddlers = 200 mg d⁻¹). Typical exposure with high dust ingestion estimates for adults were 0.01, 0.2, 0.01, 0.02 and 0.08 ng kg⁻¹ bw d⁻¹ and for toddlers 0.05, 1.9, 0.08, 0.4 and 1.12 ng kg⁻¹ bw d⁻¹ for BTBPE, DBDPE, TBB, TBPH and TBBPA-DBPE, respectively. Our results showed that, similar to PBDEs, toddlers have higher exposure to NBFRs than adults. This study documents the presence of NBFRs in indoor environments, and emphasizes the need to evaluate the health implications of exposure to such chemicals.     

Geographical distribution of non-PBDE-brominated flame retardants in mussels from Asian coastal waters

Hexabromocyclododecanes (HBCDs), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), and decabromodiphenyl ethane (DBDPE) used as alternatives for polybrominated diphenyl ethers (PBDEs) are also persistent in the environment as PBDEs. Limited information on these non-PBDE brominated flame retardants (BFRs) is available; in particular, there are only few publications on environmental pollution by these contaminants in the coastal waters of Asia. In this regard, we investigated the contamination status of HBCDs, BTBPE, and DBDPE in the coastal waters of Asia using mussels as a bioindicator. Concentrations of HBCDs, BTBPE, and DBDPE were determined in green (Perna viridis) and blue mussels (Mytilus edulis) collected from the coastal areas in Cambodia, China (mainland), SAR China (Hong Kong), India, Indonesia, Japan, Malaysia, the Philippines, and Vietnam on 2003-2008. BTBPE and DBDPE were analyzed using GC-MS, whereas HBCDs were determined by LC-MS/MS. HBCDs, BTBPE, and DBDPE were found in mussels at levels ranging from <0.01 to 1,400, <0.1 to 13, and <0.3 to 22?ng/g lipid wt, respectively. Among the three HBCD diastereoisomers, α-HBCD was the dominant isomer followed by γ- and β-HBCDs. Concentrations of HBCDs and DBDPE in mussels from Japan and Korea were higher compared to those from the other Asian countries, indicating extensive usage of these non-PBDE BFRs in Japan and Korea. Higher levels of HBCDs and DBDPE than PBDEs were detected in some mussel samples from Japan. The results suggest that environmental pollution by non-PBDE BFRs, especially HBCDs in Japan, is ubiquitous. This study provides baseline information on the contamination status of these non-PBDE BFRs in the coastal waters of Asia.     

Levels and sources of brominated flame retardants in human hair from urban, e-waste, and rural areas in South China

Human hair and indoor dust from urban, e-waste, and rural areas in south China were collected and analyzed for brominated flame retardants (BFRs). BFRs concentrations in hair from occupational e-waste recycling workers were higher than those from non-occupational exposed residents in other sampling areas. Polybrominated diphenyl ethers (PBDEs) and decabromodiphenyl ethane (DBDPE) are two major BFRs in hair samples. The PBDE congener profiles in hair from the e-waste area are different from those from urban and rural areas with relatively higher contribution of lower brominated congeners. DBDPE, instead of BDE209, has become the major BFR in non-e-waste recycling areas. Significant correlations were found between hair level and dust level for DBDPE and BTBPE but not for PBDEs. The different PBDE congener profiles between dust and hair may suggest that exogenous exposure to the PBDE adsorbed on dust is not a major source of hair PBDEs.     

Characterization of polychlorinated biphenyls and brominated flame retardants in surface soils from Surabaya, Indonesia

In this study, soil contamination by PCBs, PBDEs, HBCDs and two novel BFRs such as 1,2-bis-(2,4,6-tribromopenoxy) ethane (BTBPE) and decabromodiphenyl ethane (DBDPE) in various locations such as industrial, urban, rural, dumping site and agricultural areas of Surabaya, Indonesia has been characterized in order to evaluate their contamination status, profiles, potential sources, fate and behavior. Range and median concentrations of PCBs, PBDEs, HBCDs, BTBPE and DBDPE were ND - 9.6 (1.2), 0.069 - 24 (7.4), ND - 1.8 (0.48), ND - 1.7 (0.14) and ND - 7.6 (2.2) ng g⁻¹ dw, respectively. Industrial, urban and dumping areas were inventoried as the main sources of these pollutants. Decreasing gradient levels were observed for these contaminants from industrial district, urban, dumping site, rural and agricultural areas, in that order. Furthermore, organic carbon contents and proximity to the point sources were found as the major controlling factors. Contaminant profiles were characterized by the predominance of hexa-, hepta- and penta-homologues for PCBs; deca-, nona- and octa- for PBDEs and α-isomer for HBCDs. Product mixtures such as Ar1260/KC600 and Ar1254/KC500 for PCBs, deca- and octa-BDEs for PBDEs were the possible common formulations used in study area. To our knowledge, this is a first comprehensive study on characterization of soil contamination by PCBs, PBDEs and HBCDs together with two novel BFRs in a highly industrialized city located in tropical region. This study provides baseline information for establishing national monitoring programs in Indonesia.     

Coupling digestion in a pilot-scale UASB reactor and electrochemical oxidation over BDD anode to treat diluted cheese whey

The efficiency of the anaerobic treatment of cheese whey (CW) at mesophilic conditions was investigated. In addition, the applicability of electrochemical oxidation as an advanced post-treatment for the complete removal of chemical oxygen demand (COD) from the anaerobically treated cheese whey was evaluated. The diluted cheese whey, having a pH of 6.5 and a total COD of 6 g/L, was first treated in a 600-L, pilot-scale up-flow anaerobic sludge blanket (UASB) reactor. The UASB process, which was operated for 87 days at mesophilic conditions (32?±?2 °C) at a hydraulic retention time (HRT) of 3 days, led to a COD removal efficiency between 66 and 97 %, while the particulate matter of the wastewater was effectively removed by entrapment in the sludge blanket of the reactor. When the anaerobic reactor effluent was post-treated over a boron-doped diamond (BDD) anode at 9 and 18 A and in the presence of NaCl as the supporting electrolyte, complete removal of COD was attained after 3–4 h of reaction. During electrochemical experiments, three groups of organochlorinated compounds, namely trihalomethanes (THMs), haloacetonitriles (HANs), and haloketons (HKs), as well as 1,2-dichloroethane (DCA) and chloropicrin were identified as by-products of the process; these, alongside free chlorine, are thought to increase the matrix ecotoxicity to Artemia salina.     

Estimation and characterization of unintentionally produced persistent organic pollutant emission from converter steelmaking processes

Unintentionally produced persistent organic pollutants (UP-POPs) including polychlorinated dibenzo-p-dioxins, and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polychlorinated naphthalenes (PCNs) were characterized and quantified in stack gas and fly ash from the second ventilation systems in five typical converters in five different steelmaking plants. The 2378-substituted PCDD/Fs (2378-PCDD/Fs) and dioxin-like PCB (dl-PCBs) toxic equivalents (TEQs) were 1.84–10.3 pg WHO-TEQ Nm^?3 in the stack gas and 5.59–87.6 pg WHO-TEQ g^?1 in the fly ash, and the PCN TEQs were 0.06–0.56 pg TEQ Nm^?3 in the stack gas and 0.03–0.08 pg TEQ g^?1 in the fly ash. The concentrations of UP-POPs in the present study were generally lower than those in other metallurgical processes, such as electric arc furnaces, iron ore sintering, and secondary metallurgical processes. Adding scrap metal might increase UP-POP emissions, indicating that raw material composition was a key influence on emissions. HxCDF, HpCDF, OCDF, HpCDD, and OCDD were the dominant PCDD/Fs in the stack gas and fly ash. TeCB and PeCB were dominant in the stack gas, but HxCB provided more to the total PCB concentrations in the fly ash. The lower chlorinated PCNs were dominant in all of the samples. The 2378-PCDD/F, dl-PCB, and PCN emission factors in stack gases from the steelmaking converter processes (per ton of steel produced) were 1.88–2.89, 0.14–0.76_, and 229–759 μg t^?1, respectively.     

Occurrence, possible sources, and temporal trends of polychlorinated dibenzo-p-dioxins and dibenzofurans in water and sediment from the lower Yangtze River basin, Jiangsu and Shanghai areas of Eastern China

The concentrations, compositional profiles, and possible sources of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) in water column and surface sediment samples from the lower reaches of the Yangtze River were investigated, and the potential risks posed by these chemicals were evaluated. Concentrations of the 17 2,3,7,8-substituted PCDD/PCDF in the water and sediment samples ranged from 0.45 to 10.0 pg TEQ/L (mean 2.34 pg TEQ/L) and from 0.31 to 51 pg TEQ/g dw (mean 5.25 pg TEQ/g dw), respectively. Water and sediments from the Nanjing–Nantong sections of the Yangtze River were found to have elevated PCDD/PCDF levels, and the PCDD/PCDF TEQ concentrations in 13 sediment samples exceeded the probable effect levels (PEL), above which adverse biological effects are likely. Multivariate statistical analysis indicated that the principal PCDD/PCDF contamination source for the water and sediment was the production and use of pentachlorophenol (PCP) or sodium pentachlorophenate (PCP-Na). PCDD/PCDF concentrations were stable over time near the Yangtze River Estuary but had increased sharply in recent decades in the Nanjing–Nantong section, which will have been related to the growth in industrial activities and other anthropogenic PCDD/PCDF sources. Total organic carbon (TOC) and PCDD/PCDF concentrations correlated significantly (R?=?0.474, P?<?0.01), suggesting that TOC plays an important role in the transport and re-distribution of PCDD/PCDF in the Yangtze River basin.     

Concentrations,atmospheric partitioning,and air–water/soil surface exchange of polychlorinated dibenzo-p-dioxin and dibenzofuran along the upper reaches of the Haihe River basin,North China

Polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/PCDF) were overall measured and compared in ambient air, water, soils, and sediments along the upper reaches of the Haihe River of North China, so as to evaluate their concentrations, profiles, and to understand the processes of gas–particle partitioning and air–water/soil exchange. The following results were obtained: (1) The average concentrations (toxic equivalents, TEQs) of 2,3,7,8-PCDD/PCDF in air, water, sediment, and soil samples were 4,855 fg/m³, 9.5 pg/L, 99.2 pg/g dry weight (dw), and 56.4 pg/g (203 fg TEQ/m³, 0.46 pg TEQ/L, 2.2 pg TEQ/g dw, and 1.3 pg TEQ/g, respectively), respectively. (2) Although OCDF, 1,2,3,4,6,7,8-HpCDF, OCDD, and 1,2,3,4,6,7,8-HpCDD were the dominant congeners among four environmental sinks, obvious discrepancies of these congener and homologue patterns of PCDD/PCDF were observed still. (3) Significant linear correlations for PCDD/PCDF were observed between the gas–particle partition coefficient (K _p) and the subcooled liquid vapor pressure (P _L ⁰) and octanol–air partition coefficient (K _oa). (4) Fugacity fraction values of air–water exchange indicated that most of PCDD/PCDF homologues were dominated by net volatilization from water into air. The low-chlorinated PCDD/PCDF (tetra- to hexa-) presented a strong net volatilization from the soil into air, while high-chlorinated PCDD/PCDF (hepta- to octa-) were mainly close to equilibrium for air–soil exchange.     

Androgens,oestrogens, and progesterone concentrations in wastewater purification processes measured with capillary electrophoresis

A novel analytical-scale concept to improve reliability of detection and analysis of natural and processed wastewater samples from a purification plant was developed. A sequential sample clean-up system of polymer-based octadecyl and silane-based quaternary amine sorbents were used for concentrating human based steroid hormones and their metabolites and detecting them by UV absorption with capillary electrophoresis (CE). The water samples were collected from influent and effluent processes of the water purification plant in Helsinki, Finland.The CE methods were partial-filling micellar electrokinetic chromatography and capillary zone electrophoresis. The analysis times and method concentration levels were optimized with eight steroids at the range of 0.5–10 mg/L. Since in CE the detectable quantities were higher than the existing amounts in the process waters, the real samples needed matrix removal combined with steroid enrichment. After 20,000-fold concentration testosterone-glucoside, androstenedione, progesterone, and estradiol-glucoside could be determined in the process water samples. The amounts of individual steroids in influent and effluent waters were 0–429 and 0–207 ng/L, respectively. Correspondently, their total amounts were 735 and 212 ng/L with excellent in day and inter-day repeatability. The RSD values were less than 1, 9.7, and 19% in repeated analyses, calculated from 60 analyses during 24 h, and from 130 analyses during 15 months, respectively. The steroid removal in purification process was 65% on average. The solid particles separated in three steps during the water clean-up concept contained 9.8–45 ng/g steroids in combined dry precipitates.     

不同水处理工艺对地表水中AOC的去除效果

研究了以A江水、B河水为原水的常规处理工艺和以C湖水为原水的两种深度处理工艺对有机污染物的去除效果.对水样的AOC、TOC和UV254进行了分析,结果表明,4个工艺对AOC的去除率分别是63.6%、-97.9% 、84.2%和94.7% ;对TOC的去除率分别是61%、6.6%、66.7%和75% ;对UV254的去除率分别是17.9%、25.6%、83.3%和95.1% ,与深度处理工艺相比,常规处理工艺不能保证饮用水的生物稳定性.     

Assessment of sewage sludge bioremediation at different hydraulic retention times using mixed fungal inoculation by liquid-state bioconversion

Sustainable, environmental friendly, and safe disposal of sewage treatment plant (STP) sludge is a global expectation. Bioremediation performance was examined at different hydraulic retention times (HRT) in 3–10 days and organic loading rates (OLR) at 0.66–7.81 g chemical oxygen demand (COD) per liter per day, with mixed filamentous fungal (Aspergillus niger and Penicillium corylophilum) inoculation by liquid-state bioconversion (LSB) technique as a continuous process in large-scale bioreactor. Encouraging results were monitored in treated sludge by LSB continuous process. The highest removal of total suspended solid (TSS), turbidity, and COD were achieved at 98, 99, and 93 %, respectively, at 10 days HRT compared to control. The minimum volatile suspended solid/suspended solid implies the quality of water, which was recorded 0.59 at 10 days and 0.72 at 3 days of HRT. In treated supernatant with 88 % protein removal at 10 days of HRT indicates a higher magnitude of purification of treated sludge. The specific resistance to filtration (SRF) quantifies the performance of dewaterability; it was recorded minimum 0.049 × 10¹² m kg^?1 at 10 days of HRT, which was equivalent to 97 % decrease of SRF. The lower OLR and higher HRT directly influenced the bioremediation and dewaterability of STP sludge in LSB process. The obtained findings imply encouraging message in continuing treatment of STP sludge, i.e., bioremediation of wastewater for environmental friendly disposal in near future.     

Occurrence and removal of six pharmaceuticals and personal care products in a wastewater treatment plant employing anaerobic/anoxic/aerobic and UV processes in Shanghai,China

The occurrence and removal of six pharmaceuticals and personal care products (PPCPs) including caffeine (CF), N, N-diethyl-meta-toluamide (DEET), carbamazepine, metoprolol, trimethoprim (TMP), and sulpiride in a municipal wastewater treatment plant (WWTP) in Shanghai, China were studied in January 2013; besides, grab samples of the influent were also taken every 6 h, to investigate the daily fluctuation of the wastewater influent. The results showed the concentrations of the investigated PPCPs ranged from 17 to 11,400 ng/L in the WWTP. A low variability of the PPCP concentrations in the wastewater influent throughout the day was observed, with the relative standard deviations less than 25 % for most samples. However, for TMP and CF, the slight daily fluctuation still reflected their consumption patterns. All the target compounds except CF and DEET, exhibited poor removal efficiencies (<40 %) by biological treatment process, probably due to the low temperature in the bioreactor, which was unfavorable for activated sludge. While for the two biodegradable PPCPs, CF, and DEET, the anaerobic and oxic tank made contributions to their removal while the anoxic tank had a negative effect to their elimination. The tertiary UV treatment removed the investigated PPCPs by 5–38 %, representing a crucial polishing step to compensate for the poor removal by the biologic treatment process in winter.     

Occurrence and behaviour of pharmaceutical compounds in a Portuguese wastewater treatment plant: Removal efficiency through conventional treatment processes

Wastewater treatments can eliminate or remove a substantial amount of pharmaceutical active compounds (PhACs), but there may still be significant concentrations of them in effluents discharged into surface water bodies. Beirolas wastewater treatment plant (WWTP) is located in the Lisbon area and makes its effluent discharges into Tagus estuary (Portugal). The main objective of this study is to quantify a group of 32 PhACs in the different treatments used in this WWTP. Twelve sampling campaigns of wastewater belonging to the different treatments were made in 2013–2014 in order to study their removal efficiency. The wastewaters were analysed by solid phase extraction (SPE) and ultra-performance liquid chromatography coupled with tandem mass detection (UPLC–MS/MS). The anti-diabetics were the most frequently found in wastewater influent (WWI) and wastewater effluent (WWE) (208 and 1.7 μg/L, respectively), followed by analgesics/antipyretics (135 μg/L and < LOQ, respectively), psychostimulants (113 and 0.49 μg/L, respectively), non-steroidal anti-inflammatory drugs (33 and 2.6 μg/L, respectively), antibiotics (5.2 and 1.8 μg/L, respectively), antilipidemics (1.6 and 0.24 μg/L, respectively), anticonvulsants (1.5 and 0.63 μg/L, respectively) and beta blockers (1.3 and 0.51 μg/L, respectively). A snapshot of the ability of each treatment step to remove these target PhACs is provided, and it was found that global efficiency is strongly dependent on the efficiency of secondary treatment. Seasonal occurrence and removal efficiency was also monitored, and they did not show a significant seasonal trend.     

Simultaneous Determination of Imidacloprid,Thiacloprid, and Thiamethoxam in Soil and Water by High-performance Liquid Chromatography with Diode-array Detection

Abstract

A high-performance liquid chromatography method with diode-array detection (HPLC-DAD) is described for the determination of three neonicotinoid insecticides imidacloprid, thiacloprid, and thiamethoxam in soil and water. The soil samples were extracted with acetonitrile, while the water samples were extracted using C₁₈ cartridges. The mean recoveries plus standard deviations for spiked soil samples were 82 ± 4.2% for thiamethoxam, 99 ± 4.2% for imidacloprid and 94 ± 1.4% for thiacloprid. The recoveries for water samples ranged from 87 ± 3.4% for thiamethoxam to 97 ± 3.9% for imidacloprid and 97 ± 2.6% for thiacloprid. The limits of quantitation (LOQ) were 0.1, 0.1, 0.01 mg/kg in soil (5 g), and 2, 2, 0.5 µg/L in water (50 mL) for thiamethoxam, imidacloprid, and thiacloprid, respectively.     

Photolysis of atrazine in aqueous solution: role of process variables and reactive oxygen species

Photochemical advanced oxidation processes have been considered for the treatment of water and wastewater containing the herbicide atrazine (ATZ), a possible human carcinogen and endocrine disruptor. In this study, we investigated the effects of the photon emission rate and initial concentration on ATZ photolysis at 254 nm, an issue not usually detailed in literature. Moreover, the role of reactive oxygen species (ROS) is discussed. Photon emission rates in the range 0.87?×?10¹⁸–3.6?×?10¹⁸ photons L^?1 s^?1 and [ATZ]₀?=?5 and 20 mg L^?1 were used. The results showed more than 65 % of ATZ removal after 30 min. ATZ photolysis followed apparent first-order kinetics with k values and percent removals decreasing with increasing herbicide initial concentration. A fivefold linear increase in specific degradation rate constants with photon emission rate was observed. Also, regardless the presence of persistent degradation products, toxicity was efficiently removed after 60-min exposure to UV radiation. Experiments confirmed a noticeable contribution of singlet oxygen and radical species to atrazine degradation during photolysis. These results may help understand the behavior of atrazine in different UV-driven photochemical degradation treatment processes.     

Bioelectrochemical anaerobic sewage treatment technology for Arctic communities

This study describes a novel wastewater treatment technology suitable for small remote northern communities. The technology is based on an enhanced biodegradation of organic carbon through a combination of anaerobic methanogenic and microbial electrochemical (bioelectrochemical) degradation processes leading to biomethane production. The microbial electrochemical degradation is achieved in a membraneless flow-through bioanode–biocathode setup operating at an applied voltage below the water electrolysis threshold. Laboratory wastewater treatment tests conducted through a broad range of mesophilic and psychrophilic temperatures (5–23 °C) using synthetic wastewater showed a biochemical oxygen demand (BOD₅) removal efficiency of 90–97% and an effluent BOD₅ concentration as low as 7 mg L^?1. An electricity consumption of 0.6 kWh kg^?1 of chemical oxygen demand (COD) removed was observed. Low energy consumption coupled with enhanced methane production led to a net positive energy balance in the bioelectrochemical treatment system.     

Application of biofiltration system on AOC removal: column and field studies

The Cheng-Ching Lake Water Treatment Plant (CCLWTP) is the main supplier of domestic water for the Greater Kaohsiung area, the second largest metropolis in Taiwan. Biological activated carbon (BAC) filtration is one of the major treatment processes in CCLWTP. The objectives of this study were to evaluate the effectiveness of BAC filtration on water treatment in the studied advanced water treatment plant and its capability on pollutants [e.g., AOC (assimilable organic carbon), bromide, bromate, iron] removal. In this study, water samples from each treatment process of CCLWTP were collected and analyzed periodically to assess the variations in concentrations of AOC and other water quality indicators after each treatment unit. Moreover, the efficiency of biofiltration process using granular activated carbon (GAC) and anthracite as the fillers was also evaluated through a column experiment. Results show that the removal efficiencies for AOC, bromide, bromate, and iron are 86% 100%, 17%, and 30% after the BAC filter bed, respectively. This indicates that BAC filtration plays an important role in pollutant removal. Results also show that AOC concentrations in raw water and effluent of the CCLWTP are approximately 143 and 16 microg acetate-Cl(-1), respectively. This reveals that the treatment processes applied in CCLWTP is able to remove AOC effectively. Results of column study show that the AOC removal efficiencies in the GAC and anthracite columns are 60% and 17%, respectively. Microbial colonization on GAC and anthracite were detected via the observation of scanning electron microscopic images. The observed microorganisms included bacteria (rods, cocci, and filamentous bacteria), fungi, and protozoa. Results from this study provide us insight into the mechanisms of AOC removal by advanced water treatment processes. These findings would be helpful in designing a modified water treatment system for AOC removal and water quality improvement.     

Applicability of MIEX®DOC process for organics removal from NOM laden water

The aim of this study was to evaluate applicability of ion exchange process for organics removal from Douro River surface water at the intake of Lever water treatment plant using magnetized ion exchange resin MIEX®. Qualitative analysis of the natural organic matter present in the surface water and prediction of its amenability to removal in conventional coagulation process were assessed. Results obtained in MIEX®DOC process kinetic batch experiments allowed determination of ion exchange efficiency in dissolved organic carbon (DOC), UV absorbing organics, and true color removal. The data were compared with the efficiencies of the conventional unit processes for organics removal at Lever WTP. MIEX®DOC process revealed to be more efficient in DOC removal than conventional treatment achieving the efficiencies in the range of 61–91 %, lowering disinfection by-products formation potential of the water. DOC removal efficiency at Lever WTP depends largely on the raw water quality and ranges from 28 % for water of moderated quality to 89 % of significantly deteriorated quality. In this work, MIEX®DOC process was also used as a reference method for the determination of contribution of anionic fraction to dissolved organic matter and selectivity of the unit processes at Lever WTP for its removal.