Montreal Wastewater Treatment Plant Research Articles

Fish Exhibit Distinct Fluorochemical and δ15N Isotopic Signatures in the St. Lawrence River Impacted by Municipal Wastewater Effluents

We examined the influence of Montreal wastewater treatment plant (WWTP) effluents on two top predators, Walleye (Sander vitreus) and Sauger (Sander canadensis), with a focus on δ15N isotopic signatures and per- and polyfluoroalkyl substances (PFAS). These two fish species were collected in the summer 2013 in the St. Lawrence River upstream and downstream from a major WWTP, as well as in background sites (semi-remote lakes). Most of the δ15N variations for Sauger and Walleye are attributable to 1) δ15N values of the primary producers and sewage-derived particulate organic matter (SDPOM) at the base of the trophic food chain, 2) agricultural activities combined with biogeochemical processes, and 3) food web length. δ15N was significantly lower in fish collected in the effluent-mixed water masses than other sites of the St. Lawrence River, attributed to the SDPOM of the WWTP effluent. Relative to the background sites, certain PFAS were present at much higher levels in the St. Lawrence River, with profiles dominated by perfluoroalkyl sulfonates (PFSA). However, PFSA profiles generally remained consistent along the St. Lawrence River. PFOS levels in fish from the St. Lawrence exceeded the current Federal Environmental Quality Guidelines for protecting piscivorous mammals or birds. However, the human chronic daily intake of PFOS remained below current thresholds suggested by national agencies.

Trophic transfer of polybrominated diphenyl ethers in a recently modified freshwater food web from the St. Lawrence River, Canada

Introduction of invasive species can have a profound impact on food web structure and therefore on trophic transfer of contaminants. In the St. Lawrence River (Canada), 20 years after its first detection in the system, invasive round goby (Neogobius melanostomus) has become the main prey for several piscivorous species. To evaluate the accumulation, trophic transfer, and the ecological risk of polybrominated diphenyl ethers (PBDEs) in this recently modified freshwater food web, samples of sediment, invertebrates, fish and aquatic bird eggs and plasma were collected. Sampling sites were located upstream and at two locations downstream of the Montreal wastewater treatment plant outfall. The results suggest that the influence of the WWTP effluent on PBDEs concentrations varied among the various compartments of this recently modified freshwater food web. The results also suggest that although predatory fish have switched to consuming round goby as a prey item instead of native yellow perch, this new feeding behaviour is not expected to have important impacts on the level of transfer of PBDE within this food web. The biota-sediment accumulation factors (BSAFs) ranged from 0.6 to 436, whereas biomagnification factors (BMFs) varied between 0.2 and 475. Despite our conservative method of risk assessment, we calculated an important risk for piscivorous fish and gull eggs within this study area.

Metal contamination of the St. Lawrence River following a major release of untreated wastewater.

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Integrated spatial health assessment of yellow perch (Perca flavescens) populations from the St. Lawrence River (QC, Canada), part B: cellular and transcriptomic effects.

Multi-biological level assessments have become great tools to evaluate the health of aquatic ecosystems. Using this approach, a complementary study was designed to evaluate the health of yellow perch (Perca flavescens) populations in the St. Lawrence River (Quebec, Canada). In the present study, stress responses were compared at the transcriptomic, cellular, and tissue levels in yellow perch collected at six sites along the river: Lake St. François, Lake St. Louis (north and south), Beauregard Island and Lake St. Pierre (north and south). These results complement the physiological and chemical parameters as well as pathogen infection investigated in a companion paper published in the present issue. Thiobarbituric acid reactive substance (TBARS) analyses indicated the presence of oxidative stress in fish collected in the southern part of Lake St. Louis and at the downstream sites of Lake St. Pierre. High lipid peroxidation levels were found in the muscle of yellow perch caught at Beauregard Island, located downstream of the Montreal's wastewater treatment plant, suggesting an impact of the municipal effluent on redox homeostasis. Transcriptomic results indicated the down-regulation of genes related to lipid, glucose, and retinoid in southern Lake St. Pierre as well as a decrease in retinoid storage. Overall, biochemical and molecular markers indicated that the health status of yellow perch followed a decreasing gradient from upstream to downstream of the St. Lawrence River. This gradient is representative of the cumulative negative impacts of human activities on water and habitat quality along the river.

Effects of a major municipal effluent on the St. Lawrence River: A case study.

The St. Lawrence River (SLR) is the second largest waterway in North America. The discharge of the City of Montreal wastewater treatment plant (WWTP) represents the largest volume of treated wastewaters being released into the river. It also ranks as the largest sewage treatment plant of its kind in North America. Over the last decade, intensive multidisciplinary research has focused on assessing the impacts of Montreal wastewater effluents on the SLR. We describe the major findings of these investigations, including the determination of the fate of contaminants, bioaccumulation in fish and invertebrates, ecotoxicological measurements of aquatic animal health, evaluation of endocrine disruption, parasitism in fish, and combined effects of multiple stressors on the SLR. Impacts of the effluents from the WWTP on aquatic organisms from the SLR are both toxicological and ecological, demonstrating the need for an integrated view of the impacts of municipal effluents on aquatic ecosystems.

Degradation of Selected Acidic and Neutral Pharmaceutical Products in a Primary-Treated Wastewater by Disinfection Processes

Anti-inflammatory and anti-convulsive drugs are being detected in measurable quantities in municipal wastewaters. Some of these emerging substances undergo major transformation at the sewage treatment plant after biological and chemical treatments. The degradation of pharmaceutical products from high-quality treated wastewaters by disinfection processes is well documented. However, the effect of disinfection processes on these products in physicochemical primary-treated municipal effluents remains to be investigated. Pilot projects using ozone, performic acid and UV-radiation disinfection processes were carried out at the Montreal wastewater treatment plant. Residues of pharmaceutical products like salicylic acid, clofibric acid, ibuprofen, naproxen, triclosan, carbamazepine, diclofenac, and 2-hydroxy-ibuprofen were found in the treated wastewaters before disinfection at concentrations ranging from 42 to 2556 ng/L. Most of these substances were eliminated at a rate greater than 50% at an ozone dose of 10 mg/L. Higher removal rates (as high as 70%) were observed when 20 mg/L of ozone was used. Removal rates for UV radiation, on the other hand, were often below 10% among the substances studied. Limited removal rate was observed after UV radiation for diclofenac and triclosan (25 and 40% efficiency, respectively). The irradiation used here (25 mJ/cm2) for bacterial treatment appeared, as previously reported, to be too low to cause the significant breakdown of many of the pharmaceutical substances contained in these wastewaters. Poor reduction efficiencies (< 8%) were observed with the performic acid treatment. Further investigations on analytical methodologies are therefore needed to assess the potential impact of degradation by-products on the environment and on human health.

Determination of Basic Antidepressants and Their N-Desmethyl Metabolites in Raw Sewage and Wastewater Using Solid-Phase Extraction and Liquid Chromatography−Tandem Mass Spectrometry

A novel analytical method has been developed for the determination of six basic antidepressants (venlafaxine, sertraline, paroxetine, citalopram, amitriptyline, and fluoxetine) and four of their metabolites (O-desmethylvenlafaxine, desmethylsertraline, nortriptyline, and norfluoxetine) in raw sewage and roughly primary-treated wastewater. For analytical development purposes, two ion exchange solid-phase extraction cartridges were compared. Extracts were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with positive-mode electrospray (+ESI) and selected reaction monitoring transitions. The choice of a basic mobile phase significantly improved the instrumental sensitivity (by up to 14-fold for norfluoxetine) relative to common +ESI acidic mobile phases. In addition to the remarkable gain in sensitivity, negligible matrix effects were also observed in the raw sewage samples. Analyte recoveries ranged from 80 to 103% and effluent detection limits from 0.048 to 0.10 ng/L. Samples collected at the Montreal Wastewater Treatment Plant showed the unequivocal presence of all the target compounds at concentrations of 2-346 ng/L. The target antidepressants were also detected in samples taken from the effluent receiving waters (i.e., the St. Lawrence River) but at lower concentrations (0.41-69 ng/L). The highly sensitive proposed method constitutes one of the best means for monitoring the environmental occurrence of tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), and some of their metabolites.

Effect of Suspended Particles on Disinfection of a Physicochemical Municipal Wastewater with Peracetic Acid

Abstract The aim of this study was to elucidate the role of total suspended solids (TSS, which are claimed to be responsible for protecting embedded microorganisms) during disinfection of wastewater with peracetic acid (PAA). In particular, the focus was on a physicochemical effluent, having been treated with ferric chloride for TSS and phosphorus removal. Batch disinfection tests with various PAA dosages and contact times were carried out on the effluent from Montreal's wastewater treatment plant which uses only chemical precipitation and primary sedimentation. In addition to these samples, disinfection of “medium” and “highly” filtered effluents, obtained by sequential filtration through 120- and 10-µm nominal pore size membrane laboratory filters, was investigated. Modified second-order and Selleck model kinetics were used with moderate success to describe disinfectant consumption and microbial inactivation rates, respectively. This study showed that the overall amount of protection afforded by TSS to the microbial indicator considered (i.e., fecal coliforms in this case) was approximately 1.9 logs. TSS size was a key variable in this protection; approximately 1.3 logs and an additional 0.6 logs was the protection afforded by TSS greater than 120 µm, and between 10 µm and 120 µm, respectively. Fecal coliform inactivation of 3.8 to 7.3 logs after 40 minutes contact time could be achieved with a PAA dosage of 2 or 8 mg/L, respectively, in a highly filtered effluent.

Reduction of Photoreactivation with the Combined UV/Peracetic Acid Process or by Delayed Exposure to Visible Light

Photoreactivation of microorganisms following UV inactivation is a well-known, but complex, phenomenon. It is affected by several factors, including UV fluence, wavelength, light intensity, and exposure time to photoreactivating light. The effect on photoreactivation of a combined peracetic acid (PAA)/UV process has not been investigated. Accordingly, this study compared the degree of photoreactivation, under both sunlight and artificial lights, following UV and combined PAA/UV inactivation of fecal coliforms. Effluent samples from the Montreal Wastewater Treatment Plant (MWTP) (Quebec, Canada) were exposed, for 3 hours, to both low- and high-intensity artificial lights and sunlight. All resulted in similar photoreactivation levels. However, average photoreactivation for UV-treated wastewater samples was 1.2 logs, compared with 0.1 log for the combined PAA/UV treatment. Hence, the use of PAA in combination with UV can significantly reduce the potential for photoreactivation. To simulate the photoreactivation conditions of the MWTP effluent (which passes through a 4-km outfall tunnel with approximately 3 hours detention time), UV-treated samples were kept in the dark for 3 hours before photoreactivating light exposure. After this period, photoreactivation levels were close to zero. Hence, the effects of photoreactivation may be diminished by use of a combined disinfection scheme and/or by delaying exposure of the disinfected wastewater to light.

Determination of acidic pharmaceutical products and carbamazepine in roughly primary-treated wastewater by solid-phase extraction and gas chromatography–tandem mass spectrometry

A gas chromatography–tandem mass spectrometry (GC–MS/MS) method has been developed for the determination of selected pharmaceutical residues (carbamazepine, salicylic acid, clofibric acid, ibuprofen, 2-hydroxy-ibuprofen, fenoprofen, naproxen, ketoprofen, diclofenac, and triclosan) in sewage influent and roughly primary-treated effluent. The method involved solid-phase extraction (SPE) with polymeric sorbents, and two SPE cartridges were compared for the extraction and elution of the targeted compounds in complex matrices. A successful chemical derivatization of carbamazepine and acidic compounds using N,O-bis(trimethylsilyl) trifluoroacetamide +10% trimethylchlorosilane is also described. The quantification limits of the analytical procedure ranged from 30 to 60 ng L−1 for 500 mL of wastewater. The best recovery rates (72–102%) in spiked effluent samples were obtained with Phenomenex Strata-X™ cartridges. Detection limits (S/N = 3) were estimated at between 1 and 18 ng L−1. The reported GC–MS/MS method significantly reduces the strong matrix effects encountered with more expensive LC-MS/MS techniques. Application of the developed method showed that most selected analytes were detected at concentrations ranging from low µg L−1 to trace level ng L−1 in Montreal's wastewater treatment plant effluent and influent, as well as in the receiving waters at more than 8 km downstream of the effluent outfall. The rugged alternative analytical method is suitable for the simultaneous analysis of carbamazepine and pharmaceutical acidic residues in wastewater samples from influents and effluents that have undergone rough primary treatment.

Odor Monitoring at the City of Montreal Waste Water Treatment Plant

Odor Monitoring at the City of Montreal Waste Water Treatment Plant

Contribution of Municipal Effluents to Metal Fluxes in the St. Lawrence River

The contribution of urban effluents to the total metal fluxes carried toward the sea by the St. Lawrence, a major world river, is 60% for Ag; 8-13% for Cu, Zn, Mo, Cd, and Bi; and less than 3% for all other measured elements (Al, V, Cr, Mn, Fe Co, Ni, As, Rb, Sr, Zr, Cs, Ba, W, Re, Pb, Th, U). This is inferred from measurements at the Montreal wastewater treatment plant. Except for Ag, municipal effluents do not weigh heavily on the St. Lawrence River metal budget, likely because of the physical-chemical primary treatment applied to most effluents. Compared to direct atmospheric deposition on the surface of the river, effluents would contribute half as much Pb and one-tenth as much Zn. In contrast, effluents deliver twice as much Cd and six times as much Cu as the atmosphere. Stable Pb isotope ratios (206Pb/207Pb, 206Pb/208Pb) in suspended particulate matter from the river indicate that the total Pb content in the river water is three times higher than the pristine level. The ratios of Cr, Ni, Cu, Zn, and Cd to Al in suspended particulate matter are high as compared to pre-industrial sediments, which suggeststhattrace elementfluxes are higher today. To decrease metal levels in the St. Lawrence River further will be a challenge since the sources of metals are not well-known.

Distribution, Fate, and Behavior of Nonylphenol Ethoxylates and Degradation Products in the Dispersion Plume of a Major Municipal Wastewater Effluent

The aim of this study was to estimate the distribution, fate, and behavior of p-nonylphenols (p-NPs: p-n-nonylphenol and its isomers), nonylphenol ethoxylates (NP1–17EOs), and nonylphenol carboxylic acids (NP1–2ECs) in the municipal wastewater effluent (MWWE) of the City of Montreal, Canada, and in the receiving waters of the St. Lawrence River. The MWWE was sampled at the Montreal wastewater treatment plant, while surface water was sampled at sites located upstream and downstream of the effluent outfall. Twenty-four hour composite samples were obtained at the treatment plant on three nonconsecutive days during the summer of 2002. Water samples were filtered, then particulate and dissolved phases were extracted using Soxhlet and solid-phase extraction techniques, respectively, prior to LC/MS/MS analysis for the compounds of concern. The effluent contained essentially dissolved (75.4%, 375 kg/day) and particulate (23.7%, 118 kg/day) NP1–17EOs. By contrast, the surface water downstream of the outfall contained p-NPs at an average of 9.8% and dissolved NP1–2ECs (1.3%), as well as dissolved NP1–17EOs (86.7%) and a small fraction of particulate NP1–17EOs (2.1%). All NPnEOs and their degradation products were present in higher amounts in the dissolved phase (particulate/dissolved ratio < 1) than in the particulate phase in both the wastewater and surface water. In the surface waters downstream of the effluent outfall, an average of 89% of the particulate NP1–17EOs was rapidly released (within 1.5 h) into the dissolved phase during the physical exchange, and there were variances in changes in the phase distribution among the compounds being studied. Following this relatively fast phase transfer in the receiving waters, 30% of total NP1–17EOs were lost, 25% of p-NPs and NP1–2ECs were formed by the degradation of a fraction (6%) of NP1–17EOs, and 24% of NP1–17EOs loss remains unexplained.

Disinfection efficiency of peracetic acid, UV and ozone after enhanced primary treatment of municipal wastewater

The City of Montreal Wastewater Treatment Plant uses enhanced physicochemical processes (ferric and/or alum coagulation) for suspended solids and phosphorus removal. The objective of this study was to assess the ability of peracetic acid (PAA), UV, or ozone to inactivate the indicator organisms fecal coliforms, Enterococci, MS-2 coliphage, or Clostridium perfringens in the effluent from this plant. PAA doses to reach the target fecal coliform level of 9000 CFU/100 mL exceeded 6 mg/L; similar results were obtained for enterococci, and no inactivation of Clostridium perfringens was observed. However a 1-log reduction of MS-2 occurred at PAA doses of 1.5 mg/L and higher. It was expected that this effluent would have a high ozone demand, and would require relatively high UV fluences, because of relatively high effluent COD, iron and suspended solids concentrations, and low UV transmittance. This was confirmed herein. For UV, the inactivation curve for fecal coliforms showed the typical two-stage shape, with the target of 1000 CFU/100 mL (to account for photoreactivation) occurring in the asymptote zone at fluences >20 mJ/cm 2. In contrast, inactivation curves for MS-2 and Clostridium perfringens were linear. Clostridium perfringens was the most resistant organism. For ozone, inactivation was already observed before any residuals could be measured. The transferred ozone doses to reach target fecal coliform levels (∼2-log reduction) were 30–50 mg/L. MS-2 was less resistant, but Clostridium perfringens was more resistant than fecal coliforms. The different behaviour of the four indicator organisms studied, depending on the disinfectant, suggests that a single indicator organism might not be appropriate. The required dose of any of the disinfectants is unlikely to be economically viable, and upstream changes to the plant will be needed.