Framework to Quantify Uncertainty in Microplastic Concentrations in Wastewaters and Sludges Incorporating Analytical Recovery Information into Data Analysis.

Wastewater treatment plants (WWTPs) serve a pivotal role in transferring microplastics (MPs) from wastewater to sludge streams, thereby exerting a significant influence on their release into the environment and establishing wastewater and biosolids as vectors for MP transport and delivery. Hence, an accurate understanding of the fate and transport of MPs in WWTPs is vital. Enumeration is commonly used to estimate concentrations of MPs in performance evaluations of treatment processes, and risk assessment also typically involves MP enumeration. However, achieving high accuracy in concentration estimates is challenging due to inherent uncertainty in the analytical workflow to collect and process samples and count MPs. Here, sources of random error in MP enumeration in wastewater and other matrices were investigated using a modeling approach that addresses the sources of error associated with each step of the analysis. In particular, losses are reflected in data analysis rather than merely being measured as a validation step for MP extraction methods. A model for addressing uncertainty in the enumeration of microorganisms in water was adapted to include key assumptions relevant to the enumeration of MPs in wastewater. Critically, analytical recovery, the capacity to successfully enumerate particles considering losses and counting error, may be variable among MPs due to differences in size, shape, and type (differential analytical recovery) in addition to random variability between samples (nonconstant analytical recovery). Accordingly, differential analytical recovery among the categories of MPs was added to the existing model. This model was illustratively applied to estimate MP concentrations from simulated data and quantify uncertainty in the resulting estimates. Increasing the number of replicates, counting categories of MPs separately, and accounting for both differential and nonconstant analytical recovery improved the accuracy of MP enumeration. This work contributes to developing guidelines for analytical procedures quantifying MPs in diverse types of samples and provides a framework for enhanced interpretation of enumeration data, thereby facilitating the collection of more accurate and reliable MP data in environmental studies.

A probabilistic approach to the quantification of methane generation in sewer networks.

Quantifying greenhouse gas (GHG) emissions from the conveyance of wastewater is an essential part of emissions reduction as it can identify areas of high emissions that can be targeted for mitigative action. In this study, a Monte Carlo algorithm that employs a reach-based methane generation sub-model was developed and applied to a full-scale municipal sewer system in Ontario, Canada. The algorithm employed eight categories of random variables including sewage temperature, slope, and coefficients described in the sewer reach model. Using best estimates for the employed distributions and algorithm design choices, it was estimated that 2.1-3.0 g CH4/m3 (of total wastewater conveyed) is generated in the sewer system. Gravity reaches contributed 1.3-2.2 g CH4/m3, and force main reaches contributed 0.6-0.9 g CH4/m3, or 30% of total sewer-generated methane despite contributing only 4.4% of total network length. The results suggest that addressing force main methane generation (such as employing chemical addition) could reduce a large fraction of sewer-generated methane while only requiring action on a small fraction of sewer reaches which is consistent with literature. Extending the results from this study to all sewage generated in Canada indicates that anthropogenic emissions from the wastewater sector are increased by 28-40% if sewer-generated methane is included in the assessment. After testing alternative distributions and model designs, it was determined that replacing the fullness and temperature distributions with constant (no distribution) average conditions yielded identical results to that of the base case assessment, suggesting that these random variables can be excluded from future modelling exercises. It was also observed that treating model coefficients as random variables resulted in a significant increase in the standard deviation of estimates, indicating that much of the uncertainty in the results is due to the uncertainty associated with the model coefficients. The results were sensitive to the temperature correction coefficient in the methane generation model and the Manning's n used in flow calculations; indicating that dedicating resources to accurately characterize these values will increase model accuracy.

Benchmarking the sustainability of sludge handling systems in small wastewater treatment plants.

A benchmarking strategy was developed to assess all aspects of sludge handling in small wastewater treatment plants and tested on a cross-section of Ontario facilities. Using operational data and on-site measurements, sustainability metrics that addressed energy consumption, chemical use, biosolids quality and disposition, and greenhouse gas (GHG) emissions were estimated. Electricity consumption for sludge handling ranged from 0.9 to 3.9 kW-hours per dry kilogram of raw sludge (kWh/dry kg) with thermo-alkali hydrolysis and auto-thermal thermophilic aerobic digestion (ATAD) processes consuming the least and most electricity for stabilization, respectively. Mechanical dewatering processes consumed between 2 and 5% of total sludge handling electricity, however, associated polymer dosages were higher than literature values in some cases. Disposition fuel requirements for plants with dewatering were up to 85% lower than facilities without dewatering. Biosolids contaminant (pathogen/metals) contents were observed to be substantially below Non-Agricultural Source Material (NASM) requirements. The copper content of the hauled biosolids exhibited the highest concentration relative to the NASM limit among all plants studied, ranging from 14 to 37% among facilities practicing land application of biosolids. Four biosolid products met Class A requirements for E. coli content, including one product generated via long-term storage. Carbon emissions ranged from -119 to 299 kg CO2 equivalents per dry tonne of raw sludge (g CO2 eq./kg). Six facilities that practiced land application exhibited net-negative GHG emissions; the carbon credits gained from fertilizer production avoidance outweighed emissions associated with sludge processing and transportation. The results provide evidence that this practice is sustainable from a GHG emissions standpoint. The benchmarking approach developed and information gathered is beneficial to plant owners and operators seeking to better understand how their utility is performing relative to peers, identify areas of need and further investigation, and improve the sustainability of their operations.

Characterization of performance of full-scale tertiary membranes under stressed operating conditions.

This study sought to identify factors responsible for enhanced fouling of ultrafiltration membranes used in tertiary wastewater treatment under challenging conditions of high flow and low temperature. A detailed analysis of full-scale membrane operating data was conducted, and this was supported by data gathered through a field sampling campaign. Higher average fouling rates and average recoveries were observed during periods of highest flows and lowest temperatures. The results demonstrated that the negative impact of seasonal changes on short-term fouling are readily reversible, while hydraulically irreversible fouling, which is responsible for intermediate and long-term fouling rates, is not effectively recovered by maintenance cleans (MCs) but is recovered by recovery cleans (RCs). An examination of membrane feedwater quality revealed that high fouling rates correlated to an increase in dissolved organic carbon (DOC) concentrations, with the biopolymer fraction of the DOC being most important. Increased capillary suction time (CST) values, which indicate reduced sludge dewaterability, were also observed during high fouling events. It was concluded that seasonal variations result in the increased release of extracellular polymeric substances (EPS) by microorganisms, which leads to higher membrane fouling and worsened dewaterability of the activated sludge.

Effect of solids residence time on dynamic responses in chemical P removal.

The impact of solids residence time (SRT) on the dynamics of phosphorus (P) removal by hydrous ferric oxide (HFO) floc was characterized through experimental and modeling studies. Three abiotic process conditions were considered in systems operated over a range of SRTs (~3 to 27 days): uptake in sequencing batch reactors (SBRs) under (a) constant and (b) dynamic P loading conditions, and (c) uptake in batch sorption tests with preformed HFO solids. P removal under all conditions was characterized by an initial period of fast removal followed by a period of slower removal until pseudo-equilibrium was reached. The initial removal rate increased with increasing P concentrations and was attributed to a larger concentration gradient between soluble- and adsorbed-phase concentrations. A kinetic model was developed and found to describe the dynamic behavior of P adsorption onto HFO floc under all conditions tested. A consistent mass transfer rate coefficient (k) was found to describe mass transfer over a range of SRTs for low initial P concentrations. At elevated SRTs (23-27 days) and elevated influent P concentrations, k values were found to deviate from those estimated at reduced SRTs. Differences in process mixing conditions were reflected in the estimated rate coefficients (k). Integration of the kinetic model with existing equilibrium models in wastewater process simulators will improve the ability to predict P uptake onto HFO floc under dynamic loading conditions in water resource recovery facilities. Models that consider the kinetics of P uptake will be particularly relevant for facilities that are required to achieve ultralow P concentrations. PRACTITIONER POINTS: This work provides a kinetic model that can be integrated with existing equilibrium models in wastewater process simulators to improve the ability to predict P uptake onto HFO floc under dynamic loading conditions. This research can be used to assist WRRFs to achieve ultralow effluent P requirements.

Behavioral and molecular analyses of olfaction-mediated avoidance responses of Rana (Lithobates) catesbeiana tadpoles: Sensitivity to thyroid hormones, estrogen, and treated municipal wastewater effluent.

Olfaction is critical for survival, facilitating predator avoidance and food location. The nature of the olfactory system changes during amphibian metamorphosis as the aquatic herbivorous tadpole transitions to a terrestrial, carnivorous frog. Metamorphosis is principally dependent on the action of thyroid hormones (THs), l-thyroxine (T4) and 3,5,3'-triiodothyronine (T3), yet little is known about their influence on olfaction during this phase of postembryonic development. We exposed Taylor Kollros stage I-XIII Rana (Lithobates) catesbeiana tadpoles to physiological concentrations of T4, T3, or 17-beta-estradiol (E2) for 48h and evaluated a predator cue avoidance response. The avoidance response in T3-exposed tadpoles was abolished while T4- or E2-exposed tadpoles were unaffected compared to control tadpoles. qPCR analyses on classic TH-response gene transcripts (thra, thrb, and thibz) in the olfactory epithelium demonstrated that, while both THs produced molecular responses, T3 elicited greater responses than T4. Municipal wastewater feed stock was spiked with a defined pharmaceutical and personal care product (PPCP) cocktail and treated with an anaerobic membrane bioreactor (AnMBR). Despite substantially reduced PPCP levels, exposure to this effluent abolished avoidance behavior relative to AnMBR effluent whose feed stock was spiked with vehicle. Thibz transcript levels increased upon exposure to either effluent indicating TH mimic activity. The present work is the first to demonstrate differential TH responsiveness of the frog tadpole olfactory system with both behavioral and molecular alterations. A systems-based analysis is warranted to further elucidate the mechanism of action on the olfactory epithelium and identify further molecular bioindicators linked to behavioral response disruption.

Characterization of Hydrolysis Kinetics in Staged Anaerobic Digestion of Wastewater Treatment Sludge.

The hydrolysis of mixed primary and secondary sludges in two-stage anaerobic digestion was evaluated and compared with conventional single-stage digestion, using various temperature-phased configurations of M1-M2, M1-T3, T1-T2, and T1-M3. A dual hydrolysis model best described the hydrolysis in all tests. This model was also able to consistently estimate the readily and slowly fractions of particulate chemical oxygen demand (COD) of raw sludge used in the tests. The hydrolysis kinetic coefficients (Khyd_s and Khyd_r) estimated for the mesophilic digesters were significantly greater in the short hydraulic retention time (HRT) M1 digester than those of the extended HRT digesters. Conversely, at thermophilic temperatures only Khyd_r was greater in short HRT T1 digester when compared to the extended HRT digesters. The increased Khyd_r and reduced Khyd_s values due to staging effect were explained with surface reaction models and endogenous decay. The temperature dependency of Khyd_s and Khyd_r was also explored in the staged digesters.

Dynamic characterization of a FeCl3-dosed anaerobic membrane bioreactor (AnMBR) treating municipal wastewater.

A transient study was conducted at pilot scale to assess the impact of Fe dosage on the dynamics of biological and membrane performance of an anaerobic membrane bioreactor (AnMBR) treating authentic municipal wastewater. A transient model of the AnMBR system was employed to assist with interpretation of the observed responses in the mixed liquor under different FeCl3 dosages. A high dosage (43 mg FeCl3/LSewage) resulted in a significant accumulation of fixed suspended solids and volatile suspended solids (VSS) and reduction of colloidal COD in the mixed liquor. The elevated dosages appeared to reduce the biodegradability of VSS that was present in the raw wastewater. Intermediate dosages of FeCl3 (21-12 mg/L) had less effect on these responses and did not appear to affect VSS biodegradation. Membrane performance was significantly affected by FeCl3 dosage as indicated by reversible resistance (RR) and physically irreversible resistance (IR). RR was closely related to the colloidal COD in the mixed liquor, thus responded quickly to Fe dosage. Physically, IR had a delayed response to changes in the colloidal COD concentrations in the mixed liquor and this was attributed to the effect of slow mass transfer of colloidal matter between the mixed liquor and the membrane.

Comparison of the impacts of thermal pretreatment on waste activated sludge using aerobic and anaerobic digestion.

A range of thermal pretreatment conditions were used to evaluate the impact of high pressure thermal hydrolysis on the biodegradability of waste activated sludge (WAS) under aerobic and anaerobic conditions. It was found that pretreatment did not increase the overall extent to which WAS could be aerobically biodegraded. Thermal pretreatment transformed the biodegradable fraction of WAS (XH) to readily biodegradable chemical oxygen demand (COD) (SB) (16.5-34.6%) and slowly biodegradable COD (XB) (45.8-63.6%). The impact of pretreatment temperature and duration on WAS COD fractionation did not follow a consistent pattern as changes in COD solubilization did not correspond to the observed generation of SB through pretreatment. The pretreated WAS (PWAS) COD fractionations determined from aerobic respirometry were employed in anaerobic modeling and it was concluded that the aerobic and anaerobic biodegradability of PWAS differed. It was found that thermal pretreatment resulted in as much as 50% of the endogenous decay products becoming biodegradable in anaerobic digestion. Overall, it was concluded that the COD fractionation that was developed based upon the aerobic respirometry was valid. However, it was necessary to implement a first-order decay process that reflected changes in the anaerobic biodegradability of the endogenous products through pretreatment.

Modeling the biotransformation of trimethoprim in biological nutrient removal system.

A pilot scale biological nutrient removal (BNR) process, batch experiments and modeling exercises were employed to investigate the removal and biotransformation of trimethoprim (TMP) in a BNR activated sludge process. The concentrations of the active microbial groups - ammonia oxidizing bacteria (AOB), ordinary heterotrophic organisms (OHOs) and polyphosphate accumulating organisms (PAOs) - in the BNR bioreactor were quantified through modeling of the pilot bioreactor. The overall TMP removal efficiency for the pilot BNR process was 64 ± 14% while the TMP biotransformation efficiencies in the anaerobic, anoxic and aerobic zones were 22 ± 20%, 27 ± 8% and 36 ± 5% respectively. Batch tests with and without nitrification inhibition showed that AOB played a role in the biotransformation of TMP in BNR activated sludge. A pseudo first order model which incorporated the contributions of PAOs, OHOs and AOB to the overall biodegradation of TMP was found to describe the biodegradation of TMP in batch tests with and without nitrification inhibition. This model showed that PAOs, OHOs and AOB contributed towards the biotransformation of TMP in aerobic BNR activated sludge with the biotransformation rate constants following the trend of kAOB > kOHOs > kPAOs.

Influence of SRT and HRT on Bioprocess Performance in Anaerobic Membrane Bioreactors Treating Municipal Wastewater.

This study investigated the impact of Solid Retention Time (SRT) (40 to 100 days) and Hydraulic Retention Time (HRT) (2.5 to 8.5 hours) on the treatment of municipal wastewater in pilot and bench scale AnMBRs. The results revealed good permeate quality with respect to concentrations of COD (<40 mg/L) and BOD5 (<10 mg/L) was achieved under all conditions. Over the range of values tested SRT and HRTdid not significantly influence COD and BOD5 removal efficiencies. Extended SRTs resulted in reduced sludge production and enhanced methane production. Oversaturation of dissolved methane in permeate appears to have been responsible for a consistent lack of COD mass balance closure in all tests. After calibration of biokinetic coefficients, PetWin 4 (EnviroSim Canada) was found to effectively simulate the concentrations of particulate COD, readily biodegradable COD and acetic acid over a range of SRTs and HRTs. The calibrated saturation coefficients for hydrolysis and aceticlastic methanogenesis processes were comparable to those reported in literature. The saturation coefficient of fermentation was significantly lower than those reported in literature. The simulated methane mass flows were consistently higher than the measured values which was consistent with the lack of COD mass balance closure and was attributed to reduction of sulfate and oversaturation of the permeate with respect to Henry's Law.

Evaluation of Dechlorinating Chemicals for Spent Membrane Cleaning Solutions.

The use of dechlorinating chemicals for removal of chlorine from spent membrane cleaning solutions was investigated. Addition of calcium thiosulfate resulted in a decrease in pH at low dosages of calcium thiosulfate, but when higher dosages were used, the pH was not affected. Other dechlorinating agents (sodium bisulfite, sodium sulfite, and ascorbic acid) generated smaller pH declines than calcium thiosulfate. The declines in pH were observed after the dechlorination reaction was effectively complete and pH did not appear to influence the rate of dechlorination. The rate of dechlorination in spent cleaning solution was slower than that observed in clean water. Dechlorination with calcium thiosulfate resulted in the lowest half-life and reaction time. At lower doses (less than 565 mg/L), it was not possible to discriminate between the different dechlorinating agents. The times required for dechlorination were more sensitive to increases in dechlorination chemical dose at lower doses.

The Effect of Solids Residence Time on Chemical Phosphorus Removal in Low Concentration Applications.

The effect of solids residence time (SRT) on steady state phosphorus (P) removal when striving for ultralow concentrations through metal salt addition was studied. Lab-scale continuous flow sequencing batch reactors (SBRs) were operated under high (6.4 mg P/L; 1.4 mol Fe/mol P) and low (3.4 mg P/L; 2.6 mol Fe/mol P) influent phosphate concentrations to characterize P removal. Residual P concentrations, particle size distribution, and microscopy analyses were determined over a range of SRTs. A majority of P removal (94% with 3.4 mg P/L; 83% with 6.4 mg P/L) occurred immediately after iron (Fe) addition with additional removal in the SBRs (3.3-4.8% with 3.4 mg P/L; 5.5-8.8% with 6.4 mg P/L). Soluble P uptake was higher for SRTs ≤ 7.4 days with 3.4 mg P/L and ≤ 14.3 days with 6.4 mg P/L. Normalized P uptake (µg P/mg total suspended solids [TSS]) decreased with SRT providing evidence that aging changed floc properties relevant to P removal. Floc size was found to have no distinguishable influence on P removal. However, changes in floc morphology were consistent with P removal trends.

Preliminary evaluation of biosolids characteristics for anaerobic membrane reactors treating municipal wastewaters.

This study assessed the characteristics of biosolids of a pilot-scale anaerobic membrane bioreactor (AnMBR) treating municipal wastewater. The production of total solids (TS) and volatile solids (VS) was comparable to that reported for the extended aeration system at solids residence time (SRT) longer than 40 days. The yields of TS and VS were reduced as SRT increased from 40 to 100 days and increased with the addition of 26 mg/L of FeCl3. The AnMBR destroyed 60-82% of the VS loading in feed wastewater and hence it was concluded the biosolids met the requirements for vector attraction reduction for land application. The concentrations of volatile suspended solids and total suspended solids in the sludge were less than those reported after anaerobic digestion of conventional primary and secondary sludge mixtures, and hence dewatering of the waste stream may be required for some applications. The nutrient content in terms of total Kjeldahl nitrogen and total phosphorus was similar to that of anaerobically digested municipal sludges. The dewaterability of the biosolids was poorer than that reported for sludges from aerobic treatment and anaerobically digested sludges. Dewaterability was improved by addition of FeCl3 and reduced SRT. The biosolids met standards for land application with regards to the concentration of heavy metals but would need further treatment to meet Class B pathogen indicator criteria.

Impact of organic matter constituents on phosphorus recovery from CPR sludges.

This study evaluated the influence of organic matter (OM) constituents on the potential for recovery of P from wastewaters when FeCl3 treatment is employed for P removal. The presence of OM constituents did not influence P release from Fe-P sludges when alkaline and ascorbic acid treatments were employed. However, the overall recovery of P from wastewater was impacted by the presence of selected OM constituents through the reduction of P uptake during coagulation. The presence of protein and humic matter showed remarkably low P removal values (3.0 ± 0.4% and 23 ± 1% respectively) when compared to an inorganic control recipe (62 ± 2%). Elevated soluble Fe (SFe) residuals in the presence of proteins (87 ± 5%) and humics (51 ± 1%) indicated interactions between Fe(III) cations and negatively charged functional groups like hydroxyl, carboxyl, and phenolic groups available in these organics. Significant negative correlations between P removal and residual SFe were observed suggesting Fe solubilization by OM constituents was the mechanism responsible for reduced P removal. The findings of this study identify, for the first time, the impact of OM constituents on overall P recovery when Fe(III) salts are employed and provide insights into recoveries that can be expected when Fe is added to primary, secondary treated, and industrial wastewaters. PRACTITIONER POINTS: Low P removal values were observed for protein and humic dominated wastewater recipes. Iron(III) solubilization counted for P removal reduction by proteins and humic acids. There is no effect of OM on P release from Fe-P sludge at pH 10 and ascorbic acid treatments. OM and agent employed to release P from sludges affected overall recovery of P.

Pilot-scale evaluation of cascade anaerobic digestion of mixed municipal wastewater treatment sludges.

This work assessed the performance of a pilot-scale cascade anaerobic digestion (AD) system when treating mixed municipal wastewater treatment sludges. The cascade system was compared with a conventional continuous stirred tank reactor (CSTR) digester (control) in terms of process performance, stability, and digestate quality. The results showed that the cascade system achieved higher volatile solids removal (VSR) efficiencies (28-48%) than that of the reference (25-41%) when operated at the same solids residence time (SRT) in the range of 11-15 days. When the SRT of the cascade system was reduced to 8 days the VSR (32-36%) was only slightly less than that of the reference digester that was operated at a 15-day SRT (39-43%). Specific hydrolysis rates in the first stage of the cascade system were 66-152% higher than those of the reference. Additionally, the cascade system exhibited relatively stable effluent concentrations of volatile fatty acids (VFAs: 100-120 mg/l), while the corresponding concentrations in the control effluent demonstrated greater fluctuations (100-160 mg/l). The cascade system's effluent pH and VFA/alkalinity ratios were consistently maintained within the optimal range. During a dynamic test when the feed total solids concentration was doubled, total VFA concentrations (85-120 mg/l) in the cascade system were noticeably less than those (100-170 mg/l) of the control, while the pH and VFA/alkalinity levels remained in a stable range. The cascade system achieved higher total solids (TS) content in the dewatered digestate (19.4-26.8%) than the control (17.4-22.1%), and E. coli log reductions (2.0-4.1 log MPN/g TS) were considerably higher (p < 0.05) than those in the control (1.3-2.9 log MPN/g TS). Overall, operating multiple CSTRs in cascade mode at typical SRTs and mixed sludge ratios enhanced the performance, stability digesters, and digestate quality of AD. PRACTITIONER POINTS: Enhanced digestion of mixed sludge digestion with cascade system. Increased hydrolysis rates in the cascade system compared to a reference CSTR. More stable conditions for methanogen growth at both steady and dynamic states. Improved dewaterability and E. coli reduction of digestate from the cascade system.

A comprehensive floc model for simulating simultaneous nitrification, denitrification, and phosphorus removal.

A comprehensive floc model for simultaneous nitrification, denitrification, and phosphorus removal (SNDPR) was designed, incorporating polyphosphate-accumulating organisms (PAOs), glycogen-accumulating organisms (GAOs), intrinsic half-saturation coefficients, and explicit external mass transfer terms. The calibrated model was able to effectively describe experimental data over a range of operating conditions. The estimated intrinsic half-saturation coefficients of oxygen values for ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, ordinary heterotrophic organisms (OHOs), PAOs, and GAOs were set at 0.08, 0.18, 0.03, 0.07, and 0.1 mg/L, respectively. Simulation suggested that low dissolved oxygen (DO) environments favor K-strategist nitrifying bacteria and PAOs. In SNDPR, virtually all influent and fermentation-generated volatile fatty acids were assimilated as polyhydroxyalkanoates by PAOs in the anaerobic phase. In the aerobic phase, PAOs absorbed 997 % and 171 % of the benchmark influent total phosphorus mass loading through aerobic growth and denitrification via nitrite. These high percentages were because they were calculated relative to the influent total phosphorus, rather than total phosphorus at the end of the anaerobic period. When considering simultaneous nitrification and denitrification, about 23.1 % of influent total Kjeldahl nitrogen was eliminated through denitrification by PAOs and OHOs via nitrite, which reduced the need for both oxygen and carbon in nitrogen removal. Moreover, the microbial and DO profiles within the floc indicated a distinct stratification, with decreasing DO and OHOs, and increasing PAOs towards the inner layer. This study demonstrates a successful floc model that can be used to investigate and design SNDPR for scientific and practical purposes.

Quantifying the removal of polybrominated diphenyl ethers (PBDEs) in physical, chemical, and biological sludge treatment systems.

Polybrominated diphenyl ethers (PBDE) are priority contaminants historically used as flame retardants. PBDEs are known to occur in wastewater biosolids posing potential concerns with the beneficial land application of the biosolids. This study evaluated the removal of 21 congeners in nine full-scale sludge treatment systems including pelletization (P), alkaline stabilization (AS), and aerobic (AE) and anaerobic (AN) digestion. It is the first study to conduct a mass balance analysis of a broad spectrum of PBDEs during physical, chemical, and biological sludge treatment. The PBDE congener pattern in raw sludge and biosolids samples was consistent with commercial formulations. The fully brominated congener BDE-209 dominated biosolids from all sites with an average concentration of 620 ng/g dry weight (dw), followed by BDE-99 (173 ng/g dw) and BDE-47 (162 ng/g dw). Mass balance analysis on the P and AS processes showed no change in PBDE mass flows with treatment. However, aerobic and anaerobic digestion processes reported significant levels of removal and formation of individual congeners, though the results were not consistent between facilities. One aerobic digestion process (AE2) reported an overall average removal of 48%, whereas the other (AE1) reported very high levels of accumulation of tri- and tetraBDE congeners. Similarly, there were significant variations in PBDE behavior across the five anaerobic digestion plants studied. The plant with the longest solids retention time (SRT) (AN1) reported a moderate removal (50%) of overall PBDE loading and lower congeners, whereas other plants (AN2-AN5) showed significant low (-19%) to high (-166%) levels of formation of lower congeners. The results suggest that reduced SRTs result in formation of lower congeners while extended SRTs can lead to moderate removal of some PBDEs. Conventional sludge treatment result in low to moderate PBDE removal and advanced thermal conversion technologies may be needed to improve the contaminant removal during sludge treatment.

Implementing an adaptive, two-tiered SARS-CoV-2 wastewater surveillance program on a university campus using passive sampling.

Building-level wastewater-based surveillance (WBS) has been increasingly applied upstream from wastewater treatment plants to conduct targeted monitoring for SARS-CoV-2. In this study, a two-tiered, trigger-based wastewater surveillance program was developed on a university campus to monitor dormitory wastewater. The objective was to determine if passive sampling with cotton gauze as a sampling medium could be used to support institution-level public health action. Two nucleocapsid gene targets (N1 and N2) of SARS-CoV-2 as well as the endogenous fecal indicator pepper mild mottle virus (PMMoV) were quantified using RT-qPCR. >500 samples were analyzed during two contrasting surveillance periods. In the Fall of 2021 community viral burden was low and a tiered sampling network was able to isolate individual clinical cases at the building-scale. In the Winter of 2022 wastewater signals were quickly elevated by the emergence of the highly transmissible SARS-CoV-2 Omicron (B.1.1.529) variant. Prevalence of SARS-CoV-2 shifted surveillance objectives from isolating cases to monitoring trends, revealing both the benefits and limitations of a tiered surveillance design under different public health situations. Normalization of SARS-CoV-2 by PMMoV was not reflective of upstream population differences, suggesting saturation of the material occurred during the exposure period. The passive sampling method detected nearly all known clinical cases and in one instance was able to identify one pre-symptomatic individual days prior to confirmation by clinical test. Comparisons between campus samplers and municipal wastewater influent suggests that the spread of COVID-19 on the campus was similar to that of the broader community. The results demonstrate that passive sampling is an effective tool that can produce semi-quantitative data capable of tracking temporal trends to guide targeted public health decision-making at an institutional level. Practitioners of WBS can utilize these results to inform surveillance program designs that prioritize efficient resource use and rapid reporting.

Impact of wastewater treatment configuration and seasonal conditions on thyroid hormone disruption and stress effects in Rana catesbeiana tailfin.

Improved endocrine disrupting compound (EDC) removal is desirable in municipal wastewater treatment plants (MWWTPs) although increased removal does not always translate into reduced biological activity. Suitable methods for determining reduction in biological activity of effluents are needed. In order to determine which MWWTPs are the most effective at removing EDC activities, we operated three configurations of pilot sized biological reactors (conventional activated sludge, CAS; nitrifying activated sludge, NAS; and biological nutrient removal, BNR) receiving the same influent under simulated winter and summer conditions. As frogs are model organisms for the study of thyroid hormone (TH) action, we used the North American species Rana catesbeiana in a cultured tadpole tailfin (C-fin) assay to compare the effluents. TH-responsive (thyroid hormone receptors alpha (thra) and beta (thrb)) and stress-responsive (superoxide dismutase, catalase, and heat shock protein 30) mRNA transcript levels were examined. Effluents infrequently perturbed stress-responsive transcript abundance but thra/thrb levels were significantly altered. In winter conditions, CAS caused frequent TH perturbations while BNR caused none. In summer conditions, however, BNR caused substantial TH perturbations while CAS caused few. Our findings contrast other studies of seasonal variations of EDC removal and accentuate the importance of utilizing appropriate biological readouts for assessing EDC activities.