Wastewater Treatment Plant Emissions Research Articles

The new urban wastewater treatment directive from the perspective of the receiving rivers’ quality

BackgroundThe European Union is reformulating key water management directives: the Urban Wastewater Treatment Directive (UWWTD) and the Water Framework Directive. The UWWTD update mandates extended removal of nutrients and stricter limits on micropollutants, primarily at wastewater treatment plants with a constructed capacity above 10 000 population equivalents. The revised Environmental Quality Standards Directive expands the list of regulated pollutants and lowers permissible concentrations for priority substances, including pharmaceuticals. The present study, applied for the Central-European country Hungary as a pilot, examines the impact of the UWWTD recast on receiving water quality. Employing a mixing model to assess the impact of municipal wastewater treatment plant emissions on regional waters, the research aims to optimize resource allocation for plant improvements and enhance risk area designation methods.ResultsBased on the evaluation of 886 river water bodies, it was found that wastewater plant effluents explain most of the current river impairment. Stricter nitrogen and phosphorus standards foreseen in the UWWTD recast will reduce the fraction of water bodies failing to achieve good ecological status by ~ 10%. The introduction of the new environmental quality standards for pharmaceuticals, in particular clarithromycin and diclofenac, will reveal that almost half of the river water bodies fail to achieve the good chemical status. Even after the implementation of micropollutant removal at the largest plants, as required by the recast, this number will not improve substantially.ConclusionsThe UWWTD recast’s stricter effluent standards for nutrients are projected to remarkably reduce the number of water bodies failing to achieve good ecological status, particularly in lowland rivers. However, the chemical status for pharmaceuticals like diclofenac remains concerning, with more than 40% of streams expected to fail under the revised limits. To overcome this, it is suggested to revise how the implementation of micropollutant removal at plants is prioritized. In addition to plant constructed capacity, the receiving water’s dilution capacity is to be considered at the prioritization and the designation of areas at risk.

Source-tracing of industrial and municipal wastewater effluent in river water via fluorescence fingerprinting.

Fluorescence fingerprinting is a technique to uniquely characterize water samples based on their distinct composition of dissolved organic matter (DOM) measured via 3D fluorescence spectroscopy. It is an effective tool for monitoring the chemical composition of various water systems. This study examines a river affected by several municipal and industrial wastewater treatment plant (WWTP) effluents and aims to source-tracing them via fluorescence fingerprints based on parallel factor analysis (PARAFAC) components. Additional principal component analysis (PCA) clusters the WWTP effluents according to similarity. The results yield seven PARAFAC components characterizing the WWTP effluents. Considering the ratios among the components, these distinct fluorescence fingerprints are attributable to the studied industrial sectors: leather industry, meat processing, electronics industry, and municipal wastewater treatment. Furthermore, the fluorescence signal of the receiving river is examined by PCA and assessment of flow-weighted fluorescence intensities for source-tracing the fingerprints of the WWTP effluents. An analysis of the contribution of each WWTP effluent shows that during low flow, the fluorescence signal in the river is dominated by WWTP emissions. In contrast, during high flow events, the impact of WWTP emissions is masked by diffuse emissions. The techniques presented in this study have the potential to define generalizable fluorescence fingerprints for WWTP effluents of various industrial sectors and source-trace them in the receiving river. This approach represents a step closer to implementing complex fluorescence monitoring tools in rivers, tracing the impact of municipal and industrial WWTP effluents on riverine OM.

Seasonal variation of quantitative microbial risk assessment for three airborne enteric bacteria from wastewater treatment plant emissions

Airborne E. coli, fecal coliform, and Enterococcus are all related to sewage worker’s syndrome and therefore used as target enteric bioaerosols about researches in wastewater treatment plants (WWTPs). However, most of the studies are often inadequately carried out because they lack systematic studies reports bioaerosols emission characteristics and health risk assessments for these three enteric bacteria during seasonal variation. Therefore, quantitative microbial risk assessment based on Monte Carlo simulation was utilized in this research to assess the seasonal variations of health risks of the three enteric bioaerosols among exposure populations (academic visitors, field engineers, and office staffs) in a WWTP equipped with rotating-disc and microporous aeration modes. The results show that the concentrations of the three airborne bacteria from the rotating-disc aeration mode were 2–7 times higher than the microporous aeration mode. Field engineers had health risks 1.5 times higher than academic visitors due to higher exposure frequency. Health risks of airborne Enterococcus in summer were up to 3 times higher than those in spring and winter. Similarly, health risks associated to E. coli aerosol exposure were 0.3 times higher in summer compared to spring. In contrast, health risks associated with fecal coliform aerosol were between 2 and 19 times lower in summer compared to spring and winter seasons. Data further suggest that wearing of N95 mask could minimize health risks by 1–2 orders of magnitude. This research shed light on seasonal variation of health risks associated with bioaerosol emission from wastewater utilities.

Ground-based remote sensing of CH4 and N2O fluxes from a wastewater treatment plant and nearby biogas production with discoveries of unexpected sources.

This study is an attempt to assess CH4 and N2O emissions from all the treatment steps of a wastewater treatment plant (WWTP) in Sweden, serving 145000 persons, and an adjacent biogas production facility. We have used novel mid-IR ground-based remote sensing with a hyperspectral camera to visualize and quantify the emissions on 21 days during a year, with resulting yearly fluxes of 90.4±4.3 tonne CH4/yr and 10.9±1.3 tonne N2O/yr for the entire plant. The most highly emitting CH4 source was found to be sludge storage, which is seldom included in literature as in-situ methods are not suitable for measuring emissions extended over large surfaces, still contributing 90% to the total CH4 emission in our case. The dominating N2O source was found to be a Stable High rate Ammonia Removal Over Nitrite reactor, contributing 89% to the total N2O emissions. We also discovered several unexpected CH4 sources. Incomplete flaring of CH4 gave fluxes of at least 30kg CH4/min, corresponding to plume concentrations of 2.5%. Such highly episodic fluxes could double the plant-wide yearly emissions if they occur 2 days per year. From a distance of 250m we found a leak in the biogas production facility, corresponding to 1.1% of the CH4 produced, and that loading of organic material onto trucks from a biofertilizer storage tank contributed with high emissions during loading events. These results indicate that WWTP emissions globally may have been grossly underestimated and that it is essential to have effective methods that can measure all types of fluxes, and discover new potential sources, in order to make adequate priorities and to take effective actions to mitigate greenhouse gas emissions from WWTPs.

Combined Approaches to Predict Microplastic Emissions Within an Urbanized Estuary (Warnow, Southwestern Baltic Sea)

Microplastic river emissions are known to be one of the major sources for marine microplastic pollution. Especially urbanized estuaries localized at the land-sea interface and subjected to microplastic emissions from various sources exhibit a high microplastic discharge potential to adjacent coasts. To adapt effective measures against microplastic emissions a more detailed knowledge on the importance of various microplastic sources is necessary. As field data is scarce we combined different approaches to assess microplastic emissions into the Warnow estuary, southwestern Baltic Sea. Resulting microplastic emission estimates are based on in-situ measurements for the catchment emissions, whereas for the remaining microplastic sources within the estuary literature data on microplastic abundances, and various parameters were used (e.g. demographical, hydrological, geographical). The evaluation of the different emission scenarios revealed that the majority of microplastic is likely discharged by the Warnow river catchment (49.4%) and the separated city stormwater system (43.1%) into the estuary, followed by combined sewer discharges (6.1%). Wastewater treatment plant emissions exhibit the lowest percentage (1.4%). Our approach to estimate anti-fouling paint particles emissions from leisure and commercial shipping activities was associated with highest uncertainties. However, our results indicate the importance of this source highlighting the necessity for future research on the topic. Based on our assumptions for microplastic retention within the estuary, we estimate a potential annual emission of 152–291 billion microplastics (majority within the size class 10–100 µm) to the Baltic Sea. Considering all uncertainties of the different applied approaches, we could assess the importance of various microplastic sources which can be used by authorities to prioritize and establish emission reduction measures. Additionally, the study provides parameters for microplastic emission estimates that can be transferred from our model system to other urbanized Baltic estuaries.

Quantification of Active Ingredient Losses from Formulating Pharmaceutical Industries and Contribution to Wastewater Treatment Plant Emissions.

In this work, emissions of active pharmaceutical ingredients (APIs) from formulating pharmaceutical industries (FPIs) were investigated for the first time based on detailed production information and compared to overall API emissions in wastewater treatment plant (WWTP) effluents. At two municipal WWTPs, both receiving wastewater from several FPIs, two months' daily effluent samples were collected and measured using liquid chromatography high-resolution mass spectrometry (LC-HRMS). Thirty-three APIs formulated during the sampling period as well as >120 organic contaminants commonly present in WWTP effluents were quantified. On the basis of their time patterns and manufacturing data, industrial contributions were found for 22 of 26 APIs (85%) detected in the samples and processed by the FPIs. API emissions from FPIs led to daily concentration increases of up to 300-fold, despite pretreatment of the industrial wastewater. However, emissions from FPIs seemed to depend on the type of formulating activity, with granulation and mixing being most prone to API losses. Losses from FPIs were responsible for the highest concentrations and for up to 60% of the daily total API emissions measured. Furthermore, screening for suspects in LC-HRMS data resulted in the detection of unexpected emissions from FPIs, demonstrating the value of these data to comprehensively assess industrial API losses. Overall, this study showed that FPIs were relevant contributors of APIs emitted in the WWTP effluents, although only a minor fraction (<1%) of the total processed API quantity was lost to the wastewater, and despite the small percentage (<5%) of FPI wastewater compared to the total wastewater flow.

Role of wastewater treatment plant (WWTP) in environmental cycling of poly- and perfluoroalkyl (PFAS) compounds

The role of wastewater treatment plants (WWTP) in environmental cycling of poly- and perfluoroalkyl substances (PFASs) through aqueous effluent, sludge and air emission has been critically reviewed here. Understanding the role of WWTPs can provide better understanding of global cycling of persistent PFASs and assist in formulating relevant environmental policies. The review suggests that WWTP effluent is a major source of perfluoroalkyl acids (PFAAs) in surface water. Land application of biosolids (treated sludge) has shown preferential bioaccumulation of short chain (<C7) PFAAs in various plant compartments, leading to possible contamination of the food cycle. Elevated air concentration (1.5 to 15 times) of ?PFASs have been reported at the aeration tanks on WWTP sites, compared to reference sites not contaminated with WWTP emission. The air emission of neutral PFASs has important implications considering the long-range transport and subsequent degradation of neutral compounds leading to the occurrence of recalcitrant PFAAs in pristine remote environments. Research gap exist in terms of fate of polyfluroalkyl compounds (neutral PFASs) during wastetwater treatment and in aquatic and terrestrial environment. Considering the wide range of commercially available PFASs, measuring only perfluorocarboxylic acid (PFCA) and perfluorosulfonic acid (PFSA) can lead to underestimation of the total PFAS load derived from WWTPs. Knowledge of the various pathways of PFAS from WWTPs to receiving environments, outlined in this study, can help in adopting best possible management practices to reduce the release of PFASs from WWTPs.

Impact assessment of odours emitted by a wastewater treatment plant

Complaints from the Domingos Martins population about sewage odours in the city made the district attorney order an impact assessment of the odours emitted by the city wastewater treatment plant (WWTP). This study comprised various techniques, models and population surveys. In 2007, an odour emission model proved that the main hydrogen sulphide emitter was the aeration tank of the WWTP (13.5 g h(-1)) and such emissions, according to CALPUFF model, should be perceived in the whole Domingos Martins city centre area. In this area, 58% of those interviewed were annoyed by the WWTP odours. However, in 2009, the odour monitoring panel recorded few odour occurrences. A second population survey showed that hereafter only 20% of those interviewed were annoyed by the WWTP emissions. Odour emission and dispersion models run with 2010 data proved a drastic reduction of the WWTP aeration tank emissions and consequently the city centre was not bothered by WWTP emissions anymore. The odour emission reduction was due to the modification of the WWTP aeration tank system. Despite the odour emission reduction, houses located southeast of the WWTP were still annoyed by sewage odours. However, in this part of the town, other sources of sewage odours have been found.

An Engineering Example of Technological Transformation about Wastewater Treatment Plant

To alleviate the water pollution, the original wastewater treatment process was transformed based on the existing structures. Anaerobic-anoxic-aerobic process (A2/O process) was used as the main process, instead of the original two-stage aeration process (AB process). Pretreatment process and advanced treatment process were strengthened. After transformation, the effluent quality could meet the first class of A standard of the "municipal wastewater treatment plant emission standards" (GB18918-2002) and all the quality indexes of the treated water met the requirements of discharge standard of sewage treatment. The original structures were fully used in this transformation, saving investment, which provided a practical reference for the transformation of the wastewater treatment plants.

Spatio-temporal evaluation of organic contaminants and their transformation products along a river basin affected by urban, agricultural and industrial pollution

This study aims to assess the occurrence, fate and temporal and spatial distribution of anthropogenic contaminants in a river subjected to different pressures (industrial, agricultural, wastewater discharges). For this purpose, the Henares River basin (central Spain) can be considered a representative basin within a continental Mediterranean climate. As the studied river runs through several residential, industrial and agricultural areas, it would be expected that the chemical water quality is modified along its course. Thereby the selection of sampling points and timing of sample collection are critical factors in the monitoring of a river basin. In this study, six different monitoring campaigns were performed in 2010 and contaminants were measured at the effluent point of the main wastewater treatment plant (WWTP) in the river basin and at five different points upstream and downstream from the WWTP emission point. The target compounds evaluated were personal care products (PCPs), polycyclic aromatic hydrocarbons (PAHs) and pesticides. Results show that the river is clearly influenced by wastewater discharges and also by its proximity to agricultural areas. The contaminants detected at higher concentrations were the PCPs. The spatial distribution of the contaminants indicates that the studied contaminants persist along the river. In the time period studied no great seasonal variations of PCPs at the river collection points were observed. In contrast, a temporal trend of pesticides and PAHs was observed. Besides the target compounds, other new contaminants were identified and evaluated in the water samples, some of them being investigated for the first time in the aquatic environment. The behaviour of three important transformation products was also evaluated: 9,10-anthracenodione, galaxolide–lactone and 4-amino-musk xylene. These were found at higher concentrations than their parent compounds, indicating the significance of including the study of transformation products in the monitoring programmes.

Source apportionment of exposures to volatile organic compounds. I. Evaluation of receptor models using simulated exposure data

Four receptor-oriented source apportionment models were evaluated by applying them to simulated personal exposure data for select volatile organic compounds (VOCs) that were generated by Monte Carlo sampling from known source contributions and profiles. The exposure sources modeled are environmental tobacco smoke, paint emissions, cleaning and/or pesticide products, gasoline vapors, automobile exhaust, and wastewater treatment plant emissions. The receptor models analyzed are chemical mass balance, principal component analysis/absolute principal component scores, positive matrix factorization (PMF), and graphical ratio analysis for composition estimates/source apportionment by factors with explicit restriction, incorporated in the UNMIX model. All models identified only the major contributors to total exposure concentrations. PMF extracted factor profiles that most closely represented the major sources used to generate the simulated data. None of the models were able to distinguish between sources with similar chemical profiles. Sources that contributed <5% to the average total VOC exposure were not identified.