Sewage Concentration Research Articles

Remote monitoring and real-time abatement of odor emitted from sewer using odor sensors, wireless communication technique and microbial deodorant

<p>In this study, a new technology was introduced to monitor the odor occurrence situation at the remote site in real time and the technology to reduce sewage odor by using microbial deodorant. Long-term monitoring and full-scale test was carried out to investigate the odor concentration in the combined sewer using the real - time odor monitoring device which consist of 3 odor sensors with the wireless communication technique, and to investigate the effect of the microbial deodorant on the reduction of sewer odor. The odor monitoring device, which was fabricated using metal oxide semiconductor sensors and code division multi access communication technique, was installed at three sites of the gravity-flow type combined sewer (depth 3m and width 5m) in Gangnam, Seoul. Odor monitoring in field was carried out at the interval of 10 minutes for 304 days over the autumn, winter and summer. The measured results were transmitted to Woosong odor research center about 100km away from the site. The measured sensor value was converted to olfactory odor concentration by the co-relation equation of the sensor value and the olfactory odor concentration. As the monitoring results, more than 40,000 sewage odor data were obtained. The average odor concentration of raw sewage in combined sewer was 464 OUk, which was 321 OUk in winter and 412 OUk in autumn and 659 OUk in summer. The commercial microbial deodorant used in this study was the mixture culture of 48 microbial strains, and the microbial deodorant of 1 m3 d-1 to 2 m3 d-1 was mixed with raw sewage at the 1.5 km upstream of the site where odor complaints occurred. As the experimental results, the average odor concentration of sewage mixed with microbial deodorant was 113 OUk, which was 102 OUk in winter and 298 OUk in autumn and 153 OUk in summer. It was estimated that the odor reduction effect of sewer odor by microbial deodorant is about 74%.</p>

Temporal variability of parasites, bacterial indicators, and wastewater micropollutants in a water resource recovery facility under various weather conditions

Wastewater discharges lead to the deterioration of receiving waters through treated effluents and by-passes, combined and sanitary sewer overflows, and cross-connections to storm sewers. The influence of weather conditions on fecal indicator bacteria, pathogens and wastewater micropollutants on raw and treated sewage concentrations has not been extensively characterized. However, such data are needed to understand the effects of by-pass discharges and incomplete treatment on receiving waters. A water resource recovery facility was monitored for pathogenic parasites (Cryptosporidium oocysts, Giardia cysts), fecal indicator bacteria (Escherichia coli, Clostridium perfringens), and wastewater micropollutants (caffeine, carbamazepine, 2-hydroxycarbamazepine, acesulfame, sucralose, and aspartame) during 6 events under different weather conditions (snowmelt and trace to 32 mm 2-day cumulative precipitation). Greater intra- and inter-event variability was observed for Giardia, E. coli and C. perfringens than for studied WWMPs. Even with the addition of inflow and infiltration, daily variations dominated concentration trends. Thus, afternoon and early evening were identified as critical times with regards to high concentrations and flows for potential by-pass discharges. Peak concentrations of Giardia were observed during the June wet weather event (1010 cysts/L), with the highest flowrates relative to the mean monthly flowrate. Overall, Giardia, E. coli and C. perfringens concentrations were positively correlated with flowrate (R > 0.32, p < 0.05). In raw sewage samples collected under high precipitation conditions, caffeine, carbamazepine and its metabolite 2-OH-carbamazepine were significantly correlated (p < 0.05) with Giardia, E. coli, and C. perfringens demonstrating that they are useful markers for untreated sewage discharges. Data from the study are needed for estimating peak concentrations discharged from wastewater sources in relation to precipitation or snowmelt events.

Study on dynamic adsorption of p-nitrophenol by multi-walled carbon nanotubes dispersed cyclodextrin.

In this paper, the modified multi-walled carbon nanotubes were prepared by β-cyclodextrin denoted as β-CD-MWNTs. The structure and morphology of β-CD-MWNTs was characterized by TEM and the dynamic adsorption of p-nitrophenol on β-CD-MWNTs was studied by the Thomas model. Some affecting factors of dynamic adsorption and the adsorbent regeneration process such as the sewage concentration, the amount of absorbent in column, including the type of reagent, solid-liquid ratio, regeneration time, and regeneration times were investigated and optimized. The results indicated that the p-nitrophenol removal rate could reach 84% under stuffing 2g β-CD-MWNTs. The curves of p-nitrophenol's dynamic adsorption conformed to the Thomas model. Moreover, the adsorption capacity of regenerated β-CD-MWNTs was similar to the fresh β-CD-MWNT column. The optimal conditions of regenerations of β-CD-MWNTs were shown as follows: the type of reagent is anhydrous ethanol, the solid-liquid ratio is 200:40 (mg/mL) and the regeneration time is 120min.

Purification efficiency of zeolite and two planted grasses on sewage and relationship with carbon-nitrogen-phosphorus ratios in simulated constructed wetland system.

For achieving the economical and efficient configuration of constructed wetlands (CWs), a simulated device of vertical flow CWs was used to investigate the effects of different volume ratios of substrates to two cold-resistant plants on pollutant concentrations as well as their ratios in effluent under different inflow domestic sewage concentrations. The average removal rates (ARRs) of ammonia nitrogen, total nitrogen (TN) and total phosphorus were 82.7%, 84.9% and 80.6% respectively in the treatments with zeolite but no plants, which increased by 22.6%, 20.8% and 14.9% compared with those without zeolite and plants. However, in the treatments with zeolite and planted grasses, the ARRs of the three pollutants were over 90%, and those of chemical oxygen demand were lower. The removal rates of ammonia nitrogen, TN and total phosphorus had negative correlations with C:N and N:P ratios and positive correlations with the C:P ratios. Increasing the ratio of zeolite to soil from 1:1 to 2:1 had no significant effects in the removal efficiency. It was suggested that planting Lolium perenne or Poa annua on the substrate with a zeolite to soil volume ratio of 1:1 could be considered as the optimum combination to purify the domestic sewage in north rural areas of China.

Intensification of Biological Treatment of Industrial Wastewater in Aerotanks Using Adsorbents

The use of industrial wastes as alternative adsorbents for wastewater treatment is proposed. The effective concentration of the adsorbent was determined experimentally. The results of a study of the intensification of biological wastewater treatment using activated carbon and a pulverized coke fraction are presented. The efficiency of treatment in terms of "chemical oxygen demand" during the intake of highly concentrated sewage sludge with the use of an alternative adsorbent averaged 85 %. In the biosorption system, the conservation of the species diversity of the biocenosis of activated sludge and its purifying ability was noted. In the biological treatment system, purification efficiency was recorded on average 16 % less and destabilization of the system as a whole. The carried out researches prove expediency of use of adsorbents, including production wastes, for intensification of biological wastewater treatment in aero tanks.

Occurrence, removal and environmental risk of markers of five drugs of abuse in urban wastewater systems in South Australia.

The occurrence and fate of five drugs of abuse in raw influent and treated effluent wastewater were investigated over a period of 1year in the Adelaide region of South Australia. Four wastewater treatment plants were chosen for this study and monitored for five drugs which included cocaine in the form of its metabolite benzoylecgonine (BE), methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and two opioids (codeine and morphine) during the period April 2016 to February 2017. Alongside concentrations in raw sewage, the levels of drugs in the treated effluent were assessed and removal efficiencies were calculated. Drug concentrations were measured by mixed-mode solid phase extraction and liquid chromatography coupled to a quadrupole mass spectrometer. Drug concentrations detected in the raw wastewater ranged from 7 to 6510ng/L and < LOD to 4264ng/L in treated effluent samples. Drug removal rates varied seasonally and spatially. The mass loads of drugs discharged into the environment were in descending order: codeine > methamphetamine > morphine > MDMA > BE. Results showed that all the targeted drugs were on average incompletely removed by wastewater treatment, with removal performance highest for morphine (94%) and lowest for MDMA (58%). A screening-level environmental risk assessment was subsequently performed for the drugs based on effluent wastewater concentrations. Based on calculated risk quotients, overall environmental risk for these compounds appears low, with codeine and methamphetamine likely to pose the greatest potential risk to receiving environments. Given the recognised limitations of current ecotoxicological models and risk assessment methods for these and other pharmaceutical drugs, the potential for environmental impacts associated with the continuous discharge of these compounds in wastewater effluents should not be overlooked.

Phosphorus flows on ships: Case study from the Baltic Sea

Material flow analysis is used to identify and quantify the flow of phosphorus (P) in ship-generated food waste and wastewater. Passenger, cruise, RoPax and cargo ships in the Baltic Sea were investigated in three scenarios: (1) if all waste is discharged to sea, (2) if all waste is disposed of ashore or (3) if the food waste fraction is disposed of ashore and wastewater is treated on-board. About 107 tonnes of P is generated annually in the waste streams, with highest contribution of approximately 62 tonnes (58%) from wastewater in the ship-category RoPax. Approximately 24 tonnes of P is contained in the food waste generated by the ships in the study. Forthcoming regulations over allowed nutrient concentrations in sewage will lead to 80% reduction in P from passenger ships and can reduce about 31 tonnes of P entering the Baltic Sea environment. If both sewage and grey water instead are offloaded in port reception facilities, about 76 tonnes of P-reduction to the sea can be reached. As most phosphorus recovery practices currently only are available on land it is recommended to direct the waste streams to port reception facilities for further treatment ashore.

Operation of Moving Bed Biofilm Reactor in Terms of Organic Matter and Triethylene Glycol from Simulated Petrochemical Wastewater

Background Triethylene glycol (TEG) is an organic compound of the two-factor or di-alcohol alcohols and is used as a vinyl plasticizer. TEG has high toxicity and is classified in the chemical and polymer production group of petrochemical industry.Methods The current experimental study was conducted on a pilot scale. The total volume of the pilot study was 35.1 liters and its useful volume considering freeboard was 30 liters. The range of variables in the current study was input COD (chemical oxygen demand) (1000 - 3000 mg/L), pH (6, 7, and 8), C6H14O4 (600, 800, 1200, and 1800 mg/L), and hydraulic retention time (6, 8, 10, and 10 hours).Results The results of the study showed that by increasing the compatibility time within 30 days, the COD input to the system also increased, as the input organic loading of the system in the 10 days was 769 mg/L, and then this amount after 20 days, the time spent for 30 days was 941 mg/L, during which high concentrations of sewage could be significant. On the other hand, output organic loading also increased with the overtime and increase of the input organic loading. By increasing the moving bed biofilm reactor (MBBR) hydraulic retention time after 5 hours, residual COD level of input to the amount of 1165.2 mg/L reached 40.5 mg/L.Conclusion The obtained results showed that the MBBR system had the highest efficiency after 5 hours and optimized pH 8 for concentrations of TEG entering the system about 600 and 800 mg/L were 96.5% and 92.87%, respectively; and in the hydraulic time of 1 hour reached the efficiency of about 70% at 600 mg/L concentration, and no removal was observed in 800 mg/L, which can be concluded that in 1 hour or less and at concentrations of 800 mg/L and above, it can be used as pretreatment.

A comprehensive insight into the effects of microwave-H2O2 pretreatment on concentrated sewage sludge anaerobic digestion based on semi-continuous operation

This study gave a comprehensive insight into the effects of microwave-H2O2 pretreatment on concentrated sludge anaerobic digestion (AD). Results showed that mixture of activated sludge and pretreated sludge at mass ratio of 1:1 was efficient for enhancing AD, methane production was increased from 215.51 mL/g VSadded to 258.38 mL/g VSadded. Pretreatment resulted in the change of sludge properties, such as solubilization of organic matters, decrease of viscosity. For concentrated sludge AD, the “pH buffer system” ensured the “inhibitory steady state” during start-up period, and significant archaeal community shift from Methanosaeta to Methanosarcina ensured the true steady-state operation. Pretreatment further increased the relative abundance of functional microbia such as Bacteroidales, Clostridiales and Methanosarcina, and resulted in the decrease of viscosity of digested sludge in reactors. Based on the CFD simulation, the flow velocity became greater than the control. These comprehensive effects might contribute to enhanced efficiency of concentrated sludge AD.

Effect of urban waste water on some crop plants

The area around Meerut is rich in municipal sewage. Hence it will be worthwhile to study the effect of urban waste water on some crops under study. This pollutes waste water is generally used for irrigating crops. Due to their enormous use, these crops how been selected for the present study. The experiments have been done on physiological feature & Biochemical parameters of these crops. It was observed that the low concentration of sewage mixed with pure water for irrigation purpose is more beneficial, while the higher concentrations are harmful for crop production in general. Seedling growth was inhibited with increase in concentration and duration of experiment. At higher concentration all the seedling parts i.e. Plumule, Radicle, Residual Cotyledons, root and shoot were affected. Dry matter weight deceased with increase in concentration of sewage. In seed treatment there is slight increase at S-1, S-3 and S-6 in some cus of crops. Even it has been observed promoting effect in higher concentration of sewage also. The area around Meerut is rich in ununicpal sewage. Hence it will be worthwhile to study the effect of urban waste water on some crops under study. This polluted waste water is generally used for irrigating agriculture crops. Due to their enormous use, these crops how been selected for the present study. The experiments have been done on physiological feature & Biochemical parameters of these crops. All the parts of seedlings Plumule Radicle crease in concentration except some concentration of some viz. of different crops. However there was a slight increase in lower concentration sewage (10%, 820%) compare to control. The Acid phosphatase activity in all the 3 parts of seedlings viz. Plumule Radicle and Residual Cotyledons increased in control. However Acid phosphate activity decreased with the increase in concentration of sewage. The promotary effect have been observed in S-1 concentration of sewage of wheat CU PBW-16 and Gram CU's Sadhbhawana and Inhibitor effect have been observed in S-10 concentration of sewage. The Actitin of Acid phosphate in all the 3 parts of seedling viz. Plumule Radical and Residual Cotyledone increase in control. However Alkaline Phosphate activity decreased with the increase in concentration of sewage. The promotes effect have been observed in S-2 concentration of sewage of gram CV Sadhbhawana and S-1 Surya some promote effect was also observed in S-1 concentration of MOOng CU Pant Moong-1 and Mustard CU-1-30 Kranti, and Palak CV-All Green, Ulsi CU RLC-81 Tomato CV's Kasari-P-202 and Barley CU DWR-28 and Inhibitor effect in S-10 sewage.

Exposure to sewage from on-site sanitation and child health: a spatial analysis of linkages and externalities in peri-urban Bolivia

Abstract Exposure to fecal contamination is a leading cause of childhood infectious diseases in low- and middle-income countries. Low-quality sanitation infrastructure and inadequate maintenance can make on-site solutions prone to spillage, exposing children to sewage. This paper uses a unique dataset with independent verification of sewage in and around the parcels of more than 20,000 houses with on-site sanitation in peri-urban Bolivia. We analyze the relationship between exposure to sewage from overflowed sanitation infrastructure and the incidence of diarrhea in children under age five. The presence of sewage is associated with a 4 percentage point increase in the probability of diarrhea incidence – a relative increase of 22%. This relationship is driven by sewage within the boundaries of the property where the child resides, which is associated with a relative increase of 30% in the probability of the incidence of diarrhea. Our spatial analysis of sewage density shows that the probability of the incidence of diarrhea increases with the concentration of sewage in the immediate vicinity of the child's residence, suggesting negative spillovers from neighbors with overflowed on-site sanitation facilities. These potential negative health externalities provide a persuasive argument in favor of public interventions that adequately remove and treat fecal sludge.

Direct concentration of municipal sewage by forward osmosis and membrane fouling behavior

Forward osmosis (FO) draws attention due to its advantages compares to traditional pressure-driven membrane processes. In this study, a FO membrane concentrating system was built for sewage concentration to investigate membrane rejection, concentrating effect, membrane fouling behavior. Sewage could be concentrated to 1/10 original volume by FO membrane, while pollutants concentrating multiple could not reach 10. The FO membrane had excellent rejecting effect, with effluent COD, ammonia nitrogen, total nitrogen, total phosphorus concentration of 18, 2.5, 2.8, 0.4mg/L, respectively. The FO membrane flux was mainly associated with the draw solution (DS) concentration, which increased with DS concentration but more severe membrane fouling engendered in the meantime. Scanning electronic microscope and fourier transform infrared spectroscopy analysis indicated the formation and constitution of the fouling layer, which included humic acid, protein, and polysaccharide. After concentration, fouled FO membrane was remitted by physical and chemical cleaning, with recovery of 90% and 96%.

Optimization of the enhanced membrane coagulation reactor for sewage concentration efficiency and energy recovery

ABSTRACTThe application of an enhanced membrane coagulation reactor (E-MCR) for sewage concentration and energy recovery through anaerobic digestion (AD) was investigated. The results show that the addition of powder-activated carbon (PAC) and polyaluminum chloride (PACl) enhanced the sewage concentration efficiency and minimized the membrane fouling. The reactor was operated for 100 d with 70 d without severe fouling. The flux of 6 L/(m2 h) with sludge retention time of 2 d recorded a long-term stable performance and recovered concentrates with about 6000–9800 mg/L of chemical oxygen demand (COD) values. The concentrate was used as feed for AD using a continuous stirred tank reactor. The results show that at a thermophilic temperature of 35°C, a high biogas yield was achieved at 20 and 30 d hydraulic retention time (HRT). Meanwhile, biogas yields of 10, 220, and 295 mL/(gCOD) were achieved at 10, 20, and 30 d HRT, respectively. The addition of PAC/PACl and the low flux condition enhanced the concentration efficiency and minimized the membrane fouling during the long-term operation. Thus, with the optimization of the operation, E-MCR becomes a promising option for sewage concentration and energy recovery.

Helminth log reduction values for recycling water from sewage for the protection of human and stock health

The LRVs required to decrease HE concentrations in raw sewage to an acceptable level to manage the risk to human and livestock health were determined. An LRV of 3.0 was required to meet the HBT of 1 μDALY pppy in SE Australia where human helminth infections are not endemic. In comparison, a similar exposure volume and LRV in endemic regions would result in a HBT of 100 μDALY pppy.The risks posed by cattle- and pig-related helminths were also managed acceptably with the treatment of sewage providing an LRV of 3.0.New design equations were derived to determine LRVs based on hydraulic residence times (HRTs) in an activated sludge plant (ASP) and lagoons. The new equation for lagoons indicated that an LRV of 3.0 could be achieved with a HRT of 18 days or less.

Acute toxic effect of sewage effluent on the early life phase of an estuarine crab Scylla serrata.

The biological quality of secondary treated sewage effluent was evaluated using a toolbox approach, which combined a larval developmental bioassay and measurement of fecal indicator organisms. The zoea developmental toxicity of Scylla serrata from stage I to stage II was determined by exposing to a range of secondary treated sewage concentrations. Results indicated that the relative progress of zoea stage I to zoea stage II negatively correlated with increasing sewage concentrations. Data was analyzed statistically to determine lethal, median lethal, sublethal, low observed effect, and no observed effect concentrations. Water samples collected along the Buckingham canal discharge zone were also analyzed for its toxicity to the larval development. Fecal indicator organisms chosen to determine the water quality were E. coli, enterococci, C. perfrigens, and F+ coliphages. Concentrations of these fecal markers were determined in the raw influent, primary treated effluent, secondary treated effluent, and in four discharge zone sites. Data showed that this biological toolbox is helpful for providing baseline information on the effectiveness of the wastewater treatment and environmental health of the discharge zone.

Bioremediation of pit toilet sewage

The paper examines the efficacy of anaerobic, aerobic and denitrification reactions in reducing organic carbon (C), ammonium and nitrate concentrations in pit toilet sewage. The anaerobic character of pit toilet sewage causes nitrogen (N) to prevail as ammonium rather than as nitrate ions. Anaerobic decomposition of organic carbon is initially resorted to reduce competition for ammonium oxidation during subsequent aerobic treatment of sewage. A mixture of air-dried cattle manure, sand and gravel is used as a biobarrier medium for nitrate reduction. Cattle manure serves as an affordable organic carbon source; sand particles act as a medium for attached bacterial growth, while gravel improves the permeability of the barrier. Batch tests showed that anaerobic reactions reduce chemical oxygen demand (COD) concentration in pit toilet sewage by 85%. Comparatively, aerobic reactions reduce ammonium concentration in sewage by 77% through assimilation, nitrification and adsorption; 6–10 h of contact between the biobarrier mix and nitrate leads to acceptable levels of denitrification (residual nitrate concentration &lt; 45 mg/l). A modified twin-pit toilet that facilitates anaerobic decomposition of sewage in the first pit and aerobic treatment and denitrification of sewage in the second pit is constructed at Mulbagal town, Karnataka, India.

Influence of extraneous waters on the quality and loads of pollutants in wastewater discharged into the treatment plant

Abstract The aim of the study was to analyze an influence of an inflow penetrating into two selected small sewerage systems during a rainy weather on pollutant concentration and load in raw sewage. Studies were conducted in 2010–2015 on two small sewerage systems in Małopolska province. The studies confirmed that the inflow penetrating into the sewerage systems resulted in a decrease of pollutant concentrations in sewage. However, they also showed that this dilution was not constant for all types of pollutants. The most important outcome of the study was demonstrating that despite its diluting effect on pollutants, the intense inflow into a sewerage system resulted in an increase of a sewage pollutant load. This increase was not regular, but it was rising dramatically when the inflow share in sewage exceeded 50%. The study indicated that the inflow penetrating into the sewerage system should not be disregarded, as it actually presented a significant threat to the wastewater treatment process and in consequence to the quality of recipient waters.

Environmental Surveillance of Norovirus Genogroups I and II for Sensitive Detection of Epidemic Variants.

Sewage samples have been investigated to study the norovirus concentrations in sewage or the genotypes of noroviruses circulating in human populations. However, the statistical relationship between the concentration of the virus and the number of infected individuals and the clinical importance of genotypes or strains detected in sewage are unclear. In this study, we carried out both environmental and clinical surveillance of noroviruses for 3 years, 2013 to 2016. We performed cross-correlation analysis of the concentrations of norovirus GI or GII in sewage samples collected weekly and the reported number of gastroenteritis cases. Norovirus genotypes in sewage were also analyzed by pyrosequencing and compared with those identified in stool samples. The cross-correlation analysis found the peak coefficient (R = 0.51) at a lag of zero, indicating that the variation in the GII concentration, expressed as the log10 number of copies per milliliter, was coincident with that in the gastroenteritis cases. A total of 15 norovirus genotypes and up to 8 genotypes per sample were detected in sewage, which included all of the 13 genotypes identified in the stool samples except 2. GII.4 was most frequently detected in both sample types, followed by GII.17. Phylogenetic analysis revealed that a strain belonging to the GII.17 Kawasaki 2014 lineage had been introduced into the study area in the 2012-2013 season. An increase in GI.3 cases was observed in the 2015-2016 season, and sewage monitoring identified the presence of GI.3 in the previous season (2014-2015). Our results demonstrated that monitoring of noroviruses in sewage is useful for sensitive detection of epidemic variants in human populations.IMPORTANCE We obtained statistical evidence of the relationship between the variation in the norovirus GII concentration in sewage and that of gastroenteritis cases during the 3-year study period. Sewage sample analysis by a pyrosequencing approach enabled us to understand the temporal variation in the norovirus genotypes circulating in human populations. We found that a strain closely related to the GII.17 Kawasaki 2014 lineage had been introduced into the study area at least 1 year before its appearance and identification in clinical cases. A similar pattern was observed for GI.3; cases were reported in the 2015-2016 season, and closely related strains were found in sewage in the previous season. Our observation indicates that monitoring of noroviruses in sewage is useful for the rapid detection of an epidemic and is also sensitive enough to study the molecular epidemiology of noroviruses. Applying this approach to other enteric pathogens in sewage will enhance our understanding of their ecology.

Effects of adsorbent cake layer on membrane fouling during hybrid coagulation/adsorption microfiltration for sewage organic recovery

Direct organic recovery is an alternative option for enhanced energy recovery to achieve energy self-sufficiency or even carbon neutrality for wastewater treatment plants. Previous research reported that hybrid coagulation/adsorption microfiltration is efficient in recovering sewage organics. However, the fouling mechanism of adsorbent cake layer, which was formed during hybrid organic recovery process, needs to be evaluated to develop an appropriate fouling control strategy. In this study, the effects of adsorbent cake layer on the irreversible fouling during actual sewage concentration were analyzed quantitatively. Filtration resistance analysis based on dead-end filtration experiments provided evidences that the existence of adsorbent cake layer prevented severe irreversible fouling. After three filtration cycles, the reduced irreversible fouling by cake layer was as high as 20.84×1010m−1, which was nearly three times of the resistance 7.04×1010m−1 when no cake layer existed. This confirmed that the adsorbent cake layer controlled fouling, demonstrating that hybrid coagulation/adsorption microfiltration as a promising process for sewage organic recovery.

Understanding of Cyclic Volatile Methyl Siloxane Fate in a High Latitude Lake Is Constrained by Uncertainty in Organic Carbon-Water Partitioning.

Cyclic volatile methyl siloxanes (cVMS) are emitted to aquatic environments with wastewater effluents. Here, we evaluate the environmental behavior of three cVMS compounds (octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6)) in a high latitude lake (Storvannet, 70°N 23°E), experiencing intermittent wastewater emissions and high latitude environmental conditions (low temperatures and seasonal ice cover). Measured cVMS concentrations in lake water were below detection limits in both March and June 2014. However, mean concentrations in sediments were 207 ± 30, 3775 ± 973 and 848 ± 211 ng g-1 organic carbon for D4, D5 and D6, respectively. To rationalize measurements, a fugacity-based model for lakes (QWASI) was parametrized for Storvannet. The key removal process for cVMS from the lake was predicted to be advection due to the low hydraulic retention time of the lake, followed by volatilization. Predicted cVMS behavior was highly sensitive to the partition coefficient between organic carbon and water (KOC) and its temperature dependence. Predictions indicated lower overall persistence with decreasing temperature due to enhanced partitioning from sediments to water. Inverse modeling to predict steady-state emissions from cVMS concentrations in sediment provided unrealistically high emissions, when evaluated against measured concentrations in sewage. However, high concentrations of cVMS in sediment and low concentrations in water could be explained via a hypothetical dynamic emission scenario consistent with combined sewer overflows. The study illustrates the importance of considering compound-specific behavior of emerging contaminants that may differ from legacy organic contaminants.