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Historically, Southern California's four largest publicly owned treatment works (POTWs) were major sources of contaminants in the Southern California Bight (SCB), home to over 22 million residents and diverse marine life. This study conducted a fifty-year review (1971–2020) to assess these facilities' performance in protecting human and aquatic life. We analyzed effluent discharge flow, total annual mass emissions into SCB, and the rate of change of mass emissions in five ten-year timeframes. Results show a significant decrease in contaminant concentrations (43% to 99%) from 1971 to 2020, with most reaching historically low levels. Despite a growing population, effluent volume decreased by 23%, reflecting successful local water conservation and recycling efforts. Some constituents experienced temporary increases that later decreased. Overall, the decline in mass emissions for all constituents over fifty years highlights the POTWs' efforts to treat effluent and reduce their impact on the SCB's ecosystem. [ABSTRACT FROM AUTHOR]

Municipal wastewater treatment plants (WWTPs) are frequently suspected as significant point sources or conduits of microplastics to the environment. To directly investigate these suspicions, effluent discharges from seven tertiary plants and one secondary plant in Southern California were studied. The study also looked at influent loads, particle size/type, conveyance, and removal at these wastewater treatment facilities. Over 0.189 million liters of effluent at each of the seven tertiary plants were filtered using an assembled stack of sieves with mesh sizes between 400 and 45 μm. Additionally, the surface of 28.4 million liters of final effluent at three tertiary plants was skimmed using a 125 μm filtering assembly. The results suggest that tertiary effluent is not a significant source of microplastics and that these plastic pollutants are effectively removed during the skimming and settling treatment processes. However, at a downstream secondary plant, an average of one micro-particle in every 1.14 thousand liters of final effluent was counted. The majority of microplastics identified in this study had a profile (color, shape, and size) similar to the blue polyethylene particles present in toothpaste formulations. Existing treatment processes were determined to be very effective for removal of microplastic contaminants entering typical municipal WWTPs. [ABSTRACT FROM AUTHOR]

The release into the environment of antimicrobial compounds from both human and agricultural sources is a growing global concern. The Grand River watershed, the largest mixed-use watershed in southern Ontario, receives runoff from intensive animal production as well as municipal wastewater effluents from a rapidly increasing human population. A survey of surface waters and wastewater effluents was conducted across the watershed to assess the occurrence and distribution of several antimicrobials (i.e., trimethoprim, sulfamethoxazole, sulfamethazine, lincomycin, and monensin) and chemical indicators (i.e., ammonia, nitrate, ibuprofen, venlafaxine, atrazine) and to characterize exposure levels. The human antimicrobials trimethoprim and sulfamethoxazole were detected in the urban areas of the main channel at mean concentrations of 8 ± 7 ng/L and 31 ± 24 ng/L, respectively, but at much lower concentrations in the agricultural tributaries. In contrast, the veterinary antimicrobial sulfamethazine was detected at a mean concentration of 11 ± 9 ng/L in the main channel, and at a much higher concentration in the agricultural tributaries. Lincomycin was detected in only two river samples and not in the effluents while monensin was not detected in all samples. The herbicide atrazine was detected at very low concentrations in the surface waters of both the tributaries and the main channel. The concentrations of the antimicrobials and chemical indicators generally increased downstream of the confluences with agricultural tributaries and effluent outfalls. In the wastewater effluents, the concentrations of trimethoprim, sulfamethoxazole, ibuprofen, and venlafaxine decreased with increasing treatment levels (i.e., secondary to tertiary) as indicated by ammonia/nitrate concentrations. There was a strong correlation among trimethoprim, sulfamethoxazole, and venlafaxine in the main channel and in the wastewater effluents. While the environmental concentrations of antimicrobials in the watershed are low relative to toxicity thresholds, their persistence in the environment may be an important consideration in defining strategies for future water management. [ABSTRACT FROM AUTHOR]

Designing and building a treatment facility is complex. To succeed, engineers and operators must break down barriers and collaborate during design, construction, and the initial years of facility operations. An operator typically understands the space, mechanical requirements, and actions required for day-to-day work, and can help the engineering design team account for practical considerations. Many older treatment facilities feel stuck at their current location. They also are often limited in their ability to implement upgrades based on the footprint of the existing facilities. However, based on dialog with the city of Ellsworth, Maine, planners, operators, and engineers were able to think outside the box and develop a plan to design and build a new facility at a new off-site location that was both economical and state-of-the-art. Building a new wastewater treatment facility (WWTF) at a new location has allowed the city to address the lack of adequate sanitary wastewater infrastructure that challenged goals for expansion of the local economy. This and the cost-saving features of the new WWTF demonstrate the value of the city's decision to invest in a new facility and provide sustainable utility service. [ABSTRACT FROM AUTHOR]

Abstract: Contaminants released from wastewater treatment plants can persist in surface waters for substantial distances. Much research has gone into evaluating the fate and transport of these contaminants, but this work has often assumed constant flow from wastewater treatment plants. However, effluent discharge commonly varies widely over a 24-hour period, and this variation controls contaminant loading and can profoundly influence interpretations of environmental data. We show that methodologies relying on the normalization of downstream data to conservative elements can give spurious results, and should not be used unless it can be verified that the same parcel of water was sampled. Lagrangian sampling, which in theory samples the same water parcel as it moves downstream (the Lagrangian parcel), links hydrologic and chemical transformation processes so that the in-stream fate of wastewater contaminants can be quantitatively evaluated. However, precise Lagrangian sampling is difficult, and small deviations – such as missing the Lagrangian parcel by less than 1h – can cause large differences in measured concentrations of all dissolved compounds at downstream sites, leading to erroneous conclusions regarding in-stream processes controlling the fate and transport of wastewater contaminants. Therefore, we have developed a method termed “verified Lagrangian” sampling, which can be used to determine if the Lagrangian parcel was actually sampled, and if it was not, a means for correcting the data to reflect the concentrations which would have been obtained had the Lagrangian parcel been sampled. To apply the method, it is necessary to have concentration data for a number of conservative constituents from the upstream, effluent, and downstream sites, along with upstream and effluent concentrations that are constant over the short-term (typically 2–4h). These corrections can subsequently be applied to all data, including non-conservative constituents. Finally, we show how data from other studies can be corrected. [Copyright &y& Elsevier]

Abstract: Antibiotic transport downstream from a wastewater treatment plant effluent discharge was evaluated along stream reaches on Mud Creek, Spring Creek, and Decatur Branch in northwestern Arkansas, USA. Water and streambed samples were collected during August and September 2006 and analyzed for multiple antibiotics representing five classes (beta-lactams, macrolides, quinolones, sulfonamides, and tetracyclines). Antibiotics within the classes macrolides, quinolones, and sulfonamides were detected in the water column at all three stream reaches. Several of these same antibiotics, as well as antibiotics from the class tetracycline, were measured in streambed material at quantities significantly greater than those observed in the water column. Pseudo-partitioning coefficients ranged from 4 to >8000Lkg−1. Most of the antibiotics studied were significantly retained in the reaches at Mud Creek and Spring Creek and traveled kilometer-scale distances (S net, 3.3–20.2km) with low uptake velocities (, 2.9–16.1×10−6 ms−1) and rates (U net 0.01–37.9×10−6 μgm−2 s−1). Some antibiotics increased in concentration downstream from the effluent discharge at Decatur Branch, suggesting possible release from within the fluvial channel or additional sources along the stream reach. In general, antibiotics traveled kilometer-scale distances before significant dilution occurred through in-stream processes (e.g., advection, dispersion, sorption, uptake and/or degradation) within the fluvial channel of these effluent-dominated streams. [Copyright &y& Elsevier]

Water authorities apply a diversity of models and input data to set water quality-based emission limits in discharge permits. To illustrate the consequences of model and data selection, two complete mixing models and four mixing zone models used in Germany, the United Kingdom (UK), the Netherlands and the United States of America (USA) were selected and applied to various discharges of cadmium. The maximum allowable annual cadmium load was calculated for each model and diverging input data for upstream flow, upstream concentration, effluent flowand effluent concentration. Due to model selection, differences in pollutant loads amounted to a factor 3. Harmonization of the derivation of water quality-based emission limits is necessary to prevent widely divergent pollutant loads under comparable environmental conditions. [ABSTRACT FROM AUTHOR]

An experimental microcosm has been designed for simulating and studying impacts of a wastewater treatment plant (WTP) discharge on a freshwater/sediment ecosystem. The study was focused on the changes in biodiversity of benthic populations, especially bacteria and oligochaetes. Effluents were discharged in the Saone river, near Lyon (France) from a small treatment plant which treated domestic raw water by an activated sludge process. Freshwater and sediments were sampled in theSaone river upstream of the discharge point and placed in microcosms. Following the WTP discharge, physicochemical parameters of the overlying water column and sediments exhibited only a slight change, as compared to a reference.Characterization of the sediment bacterial populations was conducted with the Biolog and API systems. Strain identification and interpretation of data was difficult using these two systems. Bacterial taxa in the sediments increased slightly below the WTP discharge. Gram negative strains dominated in the effluents, but G+and G- bacteria were balanced in the sediments. Pseudomonas sp. and Bacillus sp., were the dominant strains. Invertebrate populations indicated an effect of the WTP discharge, with increasing of pollution resistant strains (Tubificidae) and disappearance of pollution intolerant strains such as Limnodrilus udekemianus and Quistadrilus multicoetosus.Taken as a whole, biological parameters indicated an environmental changes despite only slight changes in the physicochemistry of water. This experimental microcosm has proven to be a useful tool for studying impact of wastewater discharge on benthic populations. [ABSTRACT FROM AUTHOR]