Polybrominated diphenyl ethers in sewage sludge and treated biosolids: Effect factors and mass balance

Polybrominated diphenyl ether (PBDE) flame retardants have been consistently detected in sewage sludge and treated biosolids. Two hundred and eighty-eight samples including primary sludge (PS), waste biological sludge (WBS) and treated biosolids from fifteen wastewater treatment plants (WWTPs) in Canada were analyzed to investigate the factors affecting accumulation of PBDEs in sludge and biosolids. Factors examined included environmental/sewershed conditions and operational parameters of the WWTPs. PBDE concentrations in PS, WBS and treated biosolids were 230–82,000 ng/g, 530–8800 ng/g and 420–6000 ng/g, respectively; BDE-209,-99, and -47 were the predominant congeners. Concentrations were influenced by industrial input, leachate, and temperature. Several examinations including the measurement of BDE-202 indicated minimal debromination during wastewater treatment. Estimated solids-liquid distribution coefficients were moderately correlated to hydraulic retention time, solids loading rate, mixed liquor suspended solids, solids retention time, and removal of organic solids, indicating that PBDE partitioning to solids can be optimized by WWTPs' operational conditions. Solids treatment type strongly affected PBDE levels in biosolids: 1.5 times increase after solids digestion, therefore, digestion efficiency could be a potential factor for variability of PBDEs concentration. In contrast, alkaline treatment reduced PBDE concentrations in biosolids. Overall, mass balance approaches confirmed that PBDEs were removed from the liquid stream through partitioning to solids. Variability of PBDE levels in biosolids could result in different PBDEs burdens to agricultural land, and different exposure levels to soil organisms.     

The removal of pharmaceuticals, personal care products, endocrine disruptors and illicit drugs during wastewater treatment and its impact on the quality of receiving waters

A 5-month monitoring program was undertaken in South Wales in the UK to determine the fate of 55 pharmaceuticals, personal care products, endocrine disruptors and illicit drugs (PPCPs) in two contrasting wastewater plants utilising two different wastewater treatment technologies: activated sludge and trickling filter beds. The impact of treated wastewater effluent on the quality of receiving waters was also assessed.PPCPs were found to be present at high loads reaching 10 kg day⁻¹ in the raw sewage. Concentrations of PPCPs in raw sewage were found to correlate with their usage/consumption patterns in Wales and their metabolism. The efficiency of the removal of PPCPs was found to be strongly dependent on the technology implemented in the wastewater treatment plant (WWTP). In general, the WWTP utilising trickling filter beds resulted in, on average, less than 70% removal of all 55 PPCPs studied, while the WWTP utilising activated sludge treatment gave a much higher removal efficiency of over 85%. The monitoring programme revealed that treated wastewater effluents were the main contributors to PPCPs concentrations (up to 3 kg of PPCPs day⁻¹) in the rivers studied. Bearing in mind that in the cases examined here the WWTP effluents were also major contributors to rivers' flows (dilution factor for the studied rivers did not exceed 23 times) the effect of WWTP effluent on the quality of river water is significant and cannot be underestimated.     

Determination and occurrence of phthalates, alkylphenols, bisphenol A, PBDEs, PCBs and PAHs in an industrial sewage grid discharging to a Municipal Wastewater Treatment Plant

Industrial and urban discharges release organic contaminants which might affect the quality of receiving waters if not properly eliminated in Wastewater Treatment Plants (WWTP). This study is aimed to evaluate the source, transport and fate of contaminants of industrial origin in a sewage grid discharging to a WWTP and finally to the sea. The sampling network covered an industrial and urban area and wastewaters, influents and effluents of a WWTP were analyzed using a newly developed multiresidual method to capture a wide range contaminants (phthalates, alkylphenols, bisphenol A, PBDEs, PCBs and PAHs). Alkylphenols and phthalates followed by PAHs were the main compounds detected at levels between 0.01 to 698 µg l^− 1 in the sewage pipelines. At the WWTP influent they were detected at concentrations up to 345 µg l^− 1. The contaminant load was eliminated in a 64-92% during the primary and secondary treatment of the plant. However, alkylphenols, phthalates bisphenol A and traces of PAHs were discharged with the effluent, producing a total net input of 825 g d^− 1 to the sea. The study of wastewaters herein proposed can be used to better predict the loads into WWTP to improve treatment conditions according to specific sewage inputs and to assess the risks associated with the continuous discharge of contaminants to receiving plants.     

Burdens of PBBs, PBDEs, and PCBs in tissues of the cancer patients in the e-waste disassembly sites in Zhejiang, China

This study was conducted to explore the burdens of PBBs, PBDEs, and PCBs among cancer patients living in the e-waste disassembly sites. The contents of 23 PBB congeners, 12 PBDE congeners, and 27 PCB congeners in kidney, liver, and lung samples were measured by GC-MS. The results showed that low-brominated PBBs and PBB153 were the predominant congeners. PBDE47 were the most predominant PBDE congeners. PBDE209 were detected in > 70% of the samples, with geometric means ranging from 64.2 to 113.9 ng g^− 1 lipid. Among the three subfamilies of PHAHs, PCB concentrations were the highest. The detected levels of PHAHs were in the same order of magnitude in the three tissues, which indicated that any of the three tissues could be the suitable indicator for assessing body burdens of PHAHs. PBB contents (181-192 ng g^− 1 lipid) were obviously higher than those reported in the general USA population (3-8 ng g^− 1 lipid). PBDE levels (174.1-182.3 ng g^− 1 lipid) were comparable to those reported in the USA population, but significantly higher than those of the European population. PCBs levels were comparable to those of the European population. The high cancer incidence in the disassembly sites may be related to higher burdens of PBBs, PBDEs, and PCBs in tissues.     

Classic and novel brominated flame retardants (BFRs) in common sole (Solea solea L.) from main nursery zones along the French coasts

Brominated flame retardants (BFRs) were investigated in juvenile common sole from nursery zones situated along the French coast in 2007, 2008 and 2009. Extensive identification was performed with regard to PBDEs, novel BFRs 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and decabromodiphenylethane (DBDPE), and other non-PBDE BFRs, namely, hexabromobenzene (HBB) and 2,2′,4,4′,5,5′-hexabromobiphenyl (BB-153). Polybrominated diphenyl ether (PBDE) concentrations (Σ 14 congeners) ranged from 0.01 ng/g to 0.16 ng/g wet weight (ww) in muscle, and 0.07 ng/g to 2.8 ng/g ww in liver. Concentrations were in the lower range of those reported in the literature in other European locations. Lower PBDE concentrations, condition indices and lipid contents were observed in the Seine estuary in 2009, possibly in relation to a lower water flow. The PBDE patterns and ratios we observed suggested that juvenile sole have a relative high metabolic degradation capacity. Non-PBDE BFRs were detected at lower levels than PBDEs, i.e., within the < method detection limit - 0.005 ng/g ww range in muscle, and < method detection limit - 0.2 ng/g ww range in liver. The data obtained is of particular interest for the future monitoring of these compounds in the environment.     

Time-trends of metals and organic contaminants in sewage sludge

The occurrence of chemicals in sludge from sewage treatment plants (STPs) is of concern for human health and the environment. Legislations and regulations are put in place to minimize the release of harmful chemicals into the environment and arable land, e.g. via application of sewage sludge. Temporal trends analysis of sludge contaminants can be used to assess the effectiveness of such actions. Such analyses can be performed retrospectively, using sludge stored in environmental specimen banks, to investigate new or emerging environmental contaminants. The present study provides data from time-trend analyses of metals, persistent organic pollutants, pharmaceuticals, personal care products, and other organic compounds in sludge from Swedish. The analysis showed that sludge is a suitable matrix for time-trend studies and it can take on average 12 years (range, 5-26 years) to track an annual change of ±10% (with a power of 80%). Statistically significant trends were found for 18 out of the 77 compounds subjected to analysis, of which 75% showed decreasing trends. Triclosan and the antibiotic norfloxacin followed the same trend as the national recorded usage and decreased annually by 65% and 60%, respectively. The opposite was true for the methylsiloxanes, which showed an annual average increase of about 30%. A downward trend (about 20% year⁻¹) was observed for the polybrominated diphenylethers (PBDEs 154 and 183), while PBDE 209 increased by 16%. Further measurements are required to determine if the substitution of PBDEs by chlorinated paraffins or organophosphorus compounds have resulted in increased concentrations of the latter in sludge.     

Fate and distribution of pharmaceuticals in wastewater and sewage sludge of the conventional activated sludge (CAS) and advanced membrane bioreactor (MBR) treatment

In this paper we report on the performances of full-scale conventional activated sludge (CAS) treatment and two pilot-scale membrane bioreactors (MBRs) in eliminating various pharmaceutically active compounds (PhACs) belonging to different therapeutic groups and with diverse physico-chemical properties. Both aqueous and solid phases were analysed for the presence of 31 pharmaceuticals included in the analytical method. The most ubiquitous contaminants in the sewage water were analgesics and anti-inflammatory drugs ibuprofen (14.6-31.3 μg/L) and acetaminophen (7.1-11.4 μg/L), antibiotic ofloxacin (0.89-31.7 μg/L), lipid regulators gemfibrozil (2.0-5.9 μg/L) and bezafibrate (1.9-29.8 μg/L), β-blocker atenolol (0.84-2.8 μg/L), hypoglycaemic agent glibenclamide (0.12-15.9 μg/L) and a diuretic hydrochlorothiazide (2.3-4.8 μg/L). Also, several pharmaceuticals such as ibuprofen, ketoprofen, diclofenac, ofloxacin and azithromycin were detected in sewage sludge at concentrations up to 741.1, 336.3, 380.7, 454.7 and 299.6 ng/g dry weight. Two pilot-scale MBRs exhibited enhanced elimination of several pharmaceutical residues poorly removed by the CAS treatment (e.g., mefenamic acid, indomethacin, diclofenac, propyphenazone, pravastatin, gemfibrozil), whereas in some cases more stable operation of one of the MBR reactors at prolonged SRT proved to be detrimental for the elimination of some compounds (e.g., β-blockers, ranitidine, famotidine, erythromycin). Moreover, the anti-epileptic drug carbamazepine and diuretic hydrochlorothiazide by-passed all three treatments investigated.Furthermore, sorption to sewage sludge in the MBRs as well as in the entire treatment line of a full-scale WWTP is discussed for the encountered analytes. Among the pharmaceuticals encountered in sewage sludge, sorption to sludge could be a relevant removal pathway only for several compounds (i.e., mefenamic acid, propranolol, and loratidine). Especially in the case of loratidine the experimentally determined sorption coefficients (K_ds) were in the range 2214-3321 L/kg (mean). The results obtained for the solid phase indicated that MBR wastewater treatment yielding higher biodegradation rate could reduce the load of pollutants in the sludge. Also, the overall output load in the aqueous and solid phase of the investigated WWTP was calculated, indicating that none of the residual pharmaceuticals initially detected in the sewage sludge were degraded during the anaerobic digestion. Out of the 26 pharmaceutical residues passing through the WWTP, 20 were ultimately detected in the treated sludge that is further applied on farmland.     

Levels of brominated flame retardants and other pesistent organic pollutants in breast milk samples from Limpopo Province, South Africa

The non-occupational exposure to brominated flame retardants, and other persistent organic pollutants (POPs) was studied by collecting human breast milk samples from mothers residing in Thohoyandou area, a rural district in the Limpopo Province, northern part of South Africa (SA). Of all collected samples to be analysed (n = 28), those with large enough milk volumes, (n = 14) were quantified for polybrominated diphenyl ethers (PBDEs) (9 congeners: BDE-28, 47, 66, 99, 100, 138, 153, 154, and 183) and hexabromocyclododecane (HBCD) on a GC equipped with dual capillary columns and dual electron-capture detectors (ECD). The levels of PBDE congeners (median sumBDE 1.3 ng/g of lipids) and of HBCD were not far from levels generally found in European studies, and this study may be the first report on the presence of PBDEs and HBCD in SA breast milk. On a congener basis, the finding of comparably high BDE-183 levels suggests a specific PBDE usage, or contamination situation in SA. Apart from BFRs, the high DDT levels found in the breast milk from this area (median and maximum sumDDT levels of about 4 600 and over 20 000 ng/g of lipids, respectively; n = 28) have earlier been reported. In addition, other POPs (PCBs, HCB and HCHs) were found in SA breast milk, at relatively low levels. To conclude, measurable levels of PBDEs and HBCD, and a specific BDE congener pattern, were found in breast milk from the Limpopo province, SA. A number of other POPs, including DDTs in high levels, were also present.     

Bioaccumulation of polybrominated diphenyl ethers and hexabromocyclododecane in the northwest Atlantic marine food web

Seven species of teleost fishes comprising major prey of northwest Atlantic harbor seals were analyzed for polybrominated diphenyl ethers (PBDEs). PBDE concentrations in whole fish samples (n = 87) were compared with those measured previously in harbor seal blubber to evaluate the transfer of PBDEs from prey to predator. Hexabromocyclododecane (HBCD) concentrations were measured in three fish species to provide an initial estimation of HBCD contamination in this ecosystem. HBCD was detected in 87% of the fish samples at concentrations ranging from 2.4 to 38.1 ng/g, lw (overall mean 17.2 ± 10.2 ng/g, lw). ∑PBDE concentrations in fish ranged from 17.9 to 94 ng/g, lw (overall mean 62 ± 34 ng/g, lw). ∑PBDE concentrations in the harbor seals were two orders of magnitude higher than levels in the fish. Biomagnification factors (BMFs) from fish to seals averaged from 17 to 76, indicating that tetra- to hexa-BDEs are highly biomagnified in this marine food web. BDE-47 was the dominant congener in all samples, suggesting exposure to the penta-BDE mixture. The presence of higher brominated congeners including BDE-209 at measurable levels in fish and seal tissue, along with the very high biomagnification of BDE-153, as well as − 155, and − 154, suggests recent exposure to the octa- and deca-BDE formulations in this US coastal marine food web, as well as the additional contribution of BDE-209 debromination in fish to the loading of persistent PBDEs in the seals. This is the first study to report the occurrence of BDE-209 and other higher BDEs in commercially important marine fishes from the northwest Atlantic.     

Progress and perspectives of sludge ozonation as a powerful pretreatment method for minimization of excess sludge production

The treatment and disposal of excess sludge represents a bottleneck in wastewater treatment plants (WWTP) worldwide, due to environmental, economic, social and legal factors. The ideal solution to the problem of sludge disposal is to combine sludge reduction with the removal of pollution at the source. This paper presents an overview of the potential of ozonation in sludge reduction. The full-scale application of ozonation in excess sludge reduction is presented. Improvements in the biodegradability of the ozonated sludge were confirmed. The introduction of ozonation into activated sludge did not significantly influence effluent quality but improved the settling properties of the sludge. An operation with a suitable sludge wasting ratio seems to be necessary to prevent accumulation of inorganic and inert particles for long-term operation. Sludge ozonation to reduce excess sludge production may be economical in WWTP which have high sludge disposal costs and operational problems such as sludge foaming and bulking. The recommended ozone dose ranges from 0.03 to 0.05 g O₃/g TSS, which is appropriate to achieve a balance between sludge reduction efficiency and cost. An effort to design and optimize an economic sludge reduction process is necessary.     

Selected personal care products and endocrine disruptors in biosolids: an Australia-wide survey

Personal care products (PCPs) and endocrine disrupting compounds (EDCs) are groups of organic contaminants that have been detected in biosolids around the world. There is a shortage of data on these types on compounds in Australian biosolids, making it difficult to gain an understanding of their potential risks in the environment following land application. In this study, 14 biosolids samples were collected from 13 Australian wastewater treatment plants (WWTPs) to determine concentrations of eight compounds that are PCPs and/or EDCs: 4-t-octylphenol (4tOP), 4-nonylphenol (4NP), triclosan (TCS), bisphenol A (BPA), estrone (E1), 17β-estradiol (E2), estriol (E3) and 17α-ethinylestradiol (EE2). Concentration data were evaluated to determine if there were any differences between samples that had undergone anaerobic or aerobic treatment. The concentration data were also compared to other Australian and international data. Only 4tOP, 4NP, TCS, and BPA were detected in all samples and E1 was detected in four of the 14 samples. Their concentrations ranged from 0.05 to 3.08 mg/kg, 0.35 to 513 mg/kg, < 0.01 to 11.2 mg/kg, < 0.01 to 1.47 mg/kg and < 45 to 370 μg/kg, respectively. The samples that were obtained from WWTPs that used predominantly anaerobic treatment showed significantly higher concentrations of the compounds than those obtained from WWTPs that used aerobic treatment. Overall, 4NP, TCS and BPA concentrations in Australian biosolids were lower than global averages (by 42%, 12% and 62%, respectively) and 4tOP concentrations were higher (by 25%), however, of these differences only that for BPA was statistically significant. The European Union limit value for NP in biosolids is 50 mg/kg, which 4 of the 14 samples in this study exceeded.     

Polybrominated diphenyl ethers, perfluorinated alkylated substances, and metals in tile drainage and groundwater following applications of municipal biosolids to agricultural fields

Polybrominated diphenyl ethers (PBDEs), perfluorinated alkylated substances (PFAS), and metals were monitored in tile drainage and groundwater following liquid (LMB) and dewatered municipal biosolid (DMB) applications to silty-clay loam agricultural field plots. LMB was applied (93,500 L ha^− 1) in late fall 2005 via surface spreading on un-tilled soil (SS_LMB), and a one-pass aerator-based pre-tillage prior to surface spreading (AerWay SSD) (A). The DMB was applied (8 Mg dw ha^− 1) in early summer 2006 on the same plots by injecting DMB beneath the soil surface (DI), and surface spreading on un-tilled soil (SS_DMB). Key PBDE congeners (BDE-47, -99, -100, -153, -154, -183, -209) comprising 97% of total PBDE in LMB, had maximum tile effluent concentrations ranging from 6 to 320 ng L^− 1 during application-induced tile flow. SS_LMB application-induced tile mass loads for these PBDE congeners were significantly higher than those for control (C) plots (no LMB) (p < 0.05), but not A plots (p > 0.05). PBDE mass loss via tile (0-2 h post-application) as a percent of mass applied was ~ 0.04-0.1% and ~ 0.8-1.7% for A and SS_LMB, respectively. Total PBDE loading to soil via LMB and DMB application was 0.0018 and 0.02 kg total PBDE ha^− 1 yr^− 1, respectively. Total PBDE concentration in soil (0-0.2 m) after both applications was 115 ng g^− 1 dw, (sampled 599 days and 340 days post LMB and DMB applications respectively). Of all the PFAS compounds, only PFOS (max concentration = 17 ng L^− 1) and PFOA (12 ng L^− 1) were found above detectable limits in tile drainage from the application plots. Mass loads of metals in tile for the LMB application-induced tile hydrograph event, and post-application concentrations of metals in groundwater, showed significant (p < 0.05) land application treatment effects (SS_LMB > A > C for tile and SS_LMB and A > C for groundwater for most results). Following DMB application, no significant differences in metal mass loads in tile were found between SS_DMB and DI treatments (PBDE/PFAS were not measured). But for many metals (Cu, Se, Cd, Mo, Hg and Pb) both SS_DMB and DI loads were significantly higher than those from C, but only during < 100 days post DMB application. Clearly, pre-tilling the soil (e.g., A) prior to surface application of LMB will reduce application-based PBDE and metal contamination to tile drainage and shallow groundwater. Directly injecting DMB in soil does not significantly increase metal loading to tile drains relative to SS_DMB, thus, DI should be considered a DMB land application option.     

Release of infectious human enteric viruses by full-scale wastewater utilities

In the United States, infectious human enteric viruses are introduced daily into the environment through the discharge of treated water and the digested sludge (biosolids). In this study, a total of 30 wastewater and 6 biosolids samples were analyzed over five months (May-September 2008-2009) from five full-scale wastewater treatment plants (WWTPs) in Michigan using real-time PCR and cell culture assays. Samples were collected from four different locations at each WWTP (influent, pre-disinfection, post-disinfection and biosolids) using the 1MDS electropositive cartridge filter. Adenovirus (HAdV), enterovirus (EV) and norovirus genogroup II (NoV GGII) were detected in 100%, 67% and 10%, respectively of the wastewater samples using real-time PCR. Cytopathic effect (CPE) was present in 100% of the cell culture samples for influent, pre- and post-disinfection and biosolids with an average log concentration of 4.1 (2.9-4.7, range) 1.1 (0.0-2.3, range) and 0.5 (0.0-1.6, range) MPN/100 L and 2.1 (0.5-4.1) viruses/g, respectively. A significant log reduction in infectious viruses throughout the wastewater treatment process was observed at an average 4.2 (1.9-5.0, range) log units. A significant difference (p-value <0.05) was observed using real-time PCR data for HAdV but not for EV (p-value >0.05) removal in MBR as compared to conventional treatment. MBR treatment was able to achieve an additional 2 and 0.5 log reduction of HAdV and EV, respectively. This study has demonstrated the release of infectious enteric viruses in the final effluent and biosolids of wastewater treatment into the environment.     

Screening of antimycotics in Swedish sewage treatment plants - Waters and sludge

Concentrations of six pharmaceutical antimycotics were determined in the sewage water, final effluent and sludge of five Swedish sewage treatment plants (STPs) by solid phase extraction, liquid/solid extraction, and liquid chromatography-electrospray tandem mass spectrometry. The antimycotics were quantified by internal standard calibration. The results were used to estimate national flows that were compared to predictions based on sales figures. Fluconazole was the only one of the six investigated antimycotics that was detected (at concentrations ranging from 90 to 140 ng L⁻¹) in both raw sewage water and final effluent. Negligible amounts of this substance were removed from the aqueous phase, and its levels were below the limit of quantification in all of the analyzed sludge samples. In contrast, clotrimazole, ketoconazole and econazole were present in all of the sludge samples, at concentrations ranging between 200 and 1000 μg kg⁻¹, dry weight. There were close correlations between the national measured and predicted antimycotic mass flows. Antimycotic fate analysis, based on sales figures, indicated that 53% of the total amount of fluconazole sold appeared in the final effluents of the STPs, while 1, 155, 35, 209 and 41% of the terbinafine, clotrimazole, ketoconazole, econazole and miconazole sold appeared in the digested dewatered sludge.     

Measured physicochemical characteristics and biosolids-borne concentrations of the antimicrobial Triclocarban (TCC)

Triclocarban (TCC) is an active ingredient in antibacterial bar soaps, a common constituent of domestic wastewater, and the subject of recent criticism by consumer advocate groups and academic researchers alike. Activated sludge treatment readily removes TCC from the liquid waste stream and concentrates the antimicrobial in the solid fraction, which is often processed to produce biosolids intended for land application. Greater than half of the biosolids generated in the US are land-applied, resulting in a systematic release of biosolids-borne TCC into the terrestrial and, potentially, the aquatic environment. Multiple data gaps in the TCC literature (including basic physicochemical properties and biosolids concentrations) prevent an accurate, quantitative risk assessment of biosolids-borne TCC. We utilized the USEPA Office of Prevention, Pesticides, and Toxic Substances (OPPTS) harmonized test guidelines to measure TCC solubility and log K_ow values as 0.045 mg L⁻¹ and 3.5, respectively. The measured physicochemical 2 properties differed from computer model predictions. The mean concentration of TCC in 23 biosolids representative of multiple sludge processing methods was 19 ± 11 mg kg⁻¹.     

Brominated flame retardants in Belgian home-produced eggs: levels and contamination sources

The extent and the sources of contamination with brominated flame retardants (BFRs), such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD), in home-produced eggs from free-foraging chicken of Belgian private owners were investigated. Various factors, such as seasonal variability, exposure of chickens through diet (kitchen waste) and soil, and elimination of BFRs through eggs and faeces were assessed. PBDEs were more important than HBCD in terms of concentrations and detection frequency. Concentrations of PBDEs and HBCD in Belgian home-produced eggs were relatively low and comparable with reported levels from other European countries and the US. The concentrations of PBDEs (sum of 13 congeners, including BDE 209) ranged between not detected and 32 ng/g lipid weight (lw), with medians of 3.0 and < 2.0 ng/g lw for the autumn 2006 and spring 2007 campaigns, respectively. When present, BDE 209 was the major PBDE congener (45% of sum PBDEs). When BDE 209 was not detected, the PBDE profile was composed of PentaBDE (BDE 99 and BDE 47), with, in some cases, higher contribution of OctaBDE (BDE 183 and BDE 153). HBCD was also detected (< 0.4 and 2.9 ng/g lw for the autumn 2006 and spring 2007 campaigns, respectively), but at lower detection frequency. The highest HBCD value was 62 ng/g lw. The similarity between profiles and seasonal variations in the concentrations of BFRs in soil and eggs indicate that soil is an important source, but not the sole source, for eggs laid by free-foraging chicken. The contamination of eggs with PBDEs and HBCD appears to be of low concern for public health and the contribution of eggs to the total daily intake of PBDEs appears to be limited (10% for chicken owners and 5% for the average Belgian consumer).     

Biochar for the mitigation of nitrate leaching from soil amended with biosolids

Countries with sewage treatment plants produce on average 27 kg of dried biosolids/person/yr. Concerns about nitrate leaching limit the rate at which biosolids are added to soil. We sought to determine whether biochar, a form of charcoal that is added to soil, could reduce nitrate leaching from biosolids amended soil. We set up 24 (0.5 m × 0.75 m) lysimeters, filled with two soil types (Templeton Silt Loam and Ashley Dene silt loam) and amended with combinations of biochar (102 t/ha equivalent) and biosolids (600 and 1200 kg N/ha equivalent). Pasture and leachates were sampled over 5 months. Nitrate leaching from biochar plus biosolids amended soils were reduced to levels at or below the control treatments. Pasture N concentrations were similarly affected by biochar addition. Future research should focus on unravelling the mechanism responsible for the change in the nitrogen cycle in soils amended with biosolids and biochar.     

Degradation of phthalate esters in an activated sludge wastewater treatment plant

Efficient removal of phthalate esters (PE) in wastewater treatment plants (WWTP) is becoming an increasing priority in many countries. In this study, we examined the fate of dimethyl phthalate (DMP), dibutyl phthalate (DBP), butylbenzyl phthalate (BBP), and di-(2-ethylhexyl) phthalate (DEHP) in a full scale activated sludge WWTP with biological removal of nitrogen and phosphorus. The mean concentrations of DMP, DBP, BBP, and DEHP at the WWTP inlet were 1.9, 20.5, 37.9, and 71.9 μg/L, respectively. Less than 0.1%, 42%, 35%, and 96% of DMP, DBP, BBP, and DEHP was associated with suspended solids, respectively. The overall microbial degradation of DMP, DBP, BBP, and DEHP in the WWTP was estimated to be 93%, 91%, 90%, and 81%, respectively. Seven to nine percent of the incoming PE were recovered in the WWTP effluent. Factors affecting microbial degradation of DEHP in activated sludge were studied using [U-¹⁴C-ring] DEHP as tracer. First order rate coefficients for aerobic DEHP degradation were 1.0×10⁻², 1.4×10⁻², and 1.3×10⁻³ at 20, 32, and 43 °C, respectively. Aerobic degradation rates decreased dramatically under aerobic thermophilic conditions (<0.1×10⁻² h⁻¹ at 60 °C). The degradation rate under anoxic denitrifying conditions was 0.3×10⁻² h⁻¹, whereas the rate under alternating conditions (aerobic-anoxic) was 0.8×10⁻² h⁻¹. Aerobic DEHP degradation in activated sludge samples was stimulated 5-9 times by addition of a phthalate degrading bacterium. The phthalate degrading bacterium was isolated from activated sludge, and maintained a capacity for DEHP degradation while growing on vegetable oil. Collectively, the results of the study identified several controls of microbial PE degradation in activated sludge. These controls may be considered to enhance PE degradation in activated sludge WWTP with biological removal of nitrogen and phosphorus.     

Comparing steroid estrogen, and nonylphenol content across a range of European sewage plants with different treatment and management practices

The effluent of 17 sewage treatment works (STW) across Norway, Sweden, Finland, The Netherlands, Belgium, Germany, France and Switzerland was studied for the presence of estradiol (E2), estrone (E1), ethinylestradiol (EE2) and nonylphenol (NP). Treatment processes included primary and chemical treatment only, submerged aerated filter, oxidation ditch, activated sludge (AS) and combined trickling filter with activated sludge. The effluent strength ranged between 87 and 846 L/PE (population equivalent), the total hydraulic retention time (HRT) ranged between 4 and 120 h, sludge retention time (SRT) between 3 and 30 d, and water temperature ranged from 12 to 21 °C. The highest estrogen values were detected in the effluent of the STW which only used primary treatment (13 ng/L E2 and 35 ng/L E1) and on one occasion in one of the STW using the AS system (6.5 ng/L E2, 50.5 ng/L E1, but on three other occasions the concentrations in this STW were at least a factor of 6 lower). For the 16 STW employing secondary treatment E2 was only detected in the effluent of six works during the study period (average 0.7-5.7 ng/L). E1 was detected in the effluent of 13 of the same STW. The median value for E1 for the 16 STW with secondary treatment was 3.0 ng/L. EE2 was only detected in two STW (1.1, <0.8-2.8 ng/L). NP could be detected in the effluent of all 14 STW where this measurement was attempted, with a median of 0.31 μg/L and values ranging from 0.05 to 1.31 μg/L. A comparison of removal performance for E1 was carried out following prediction of the probable influent concentration. A weak but significant (α<5%) correlation between E1 removal and HRT or SRT was observed.