Impact Of Wastewater Treatment Plants Research Articles

The impact of wastewater treatment plants on the composition and toxicity of pollutants in urban rivers in Nanjing, China

Widespread wastewater pollution is one of the biggest challenges threatening the ecological health of rivers. It is crucial to identify the toxic changes of effluents after entering urban rivers as well as the toxic substances in the complex chemical mixtures found in these urban rivers. This study used HepG2 cell line for cytotoxicity test to evaluate the ecological impact of effluents on urban rivers. Water samples were collected from the Xingwu River and Yunliang River in Nanjing, China. The bacterial communities in the lower reaches of urban rivers were altered due to the differences in total nitrogen and nitrate nitrogen. The complex chemical mixtures collected in the urban rivers were divided into 10 fractions, >100 chemicals were screened in each fraction. The substances with LC50 < 1000 mg/L were listed as toxic substances, and the number of toxic substances dominated the toxicity of urban rivers. Our study highlights toxicity as a comprehensive indicator for assessing river pollutants and reveals relationship between the number of toxic substance and river toxicity. These findings have direct implications for the monitoring and management of environmental stressors and the protection of aquatic organisms and human health.

Variable contribution of wastewater treatment plant effluents to downstream nitrous oxide concentrations and emissions

Abstract. Nitrous oxide (N2O), a potent greenhouse gas and ozone-destroying agent, is produced during nitrogen transformations in both natural and human-constructed environments. Wastewater treatment plants (WWTPs) produce and emit N2O into the atmosphere during the nitrogen removal process. However, the impact of WWTPs on N2O emissions in downstream aquatic systems remains poorly constrained. By measuring N2O concentrations at a monthly resolution over a year in the Potomac River estuary, a tributary of the Chesapeake Bay in the eastern United States, we found a strong seasonal variation in N2O concentrations and fluxes: N2O concentrations were larger in fall and winter, but the flux was larger in summer and fall. Observations at multiple stations across the Potomac River estuary revealed hotspots of N2O emissions downstream of WWTPs. N2O concentrations were higher at stations downstream of WWTPs compared to other stations (median: 21.2 nM vs. 16.2 nM) despite the similar concentration of dissolved inorganic nitrogen, suggesting the direct discharge of N2O from WWTPs into the aquatic system or a higher N2O production yield in waters influenced by WWTPs. Meta-analysis of N2O measurements associated with WWTPs globally revealed variable influence of WWTPs on downstream N2O concentrations and emissions. Since wastewater production has increased substantially with the growing population and is projected to continue to rise, accurately accounting for N2O emissions downstream of WWTPs is important for constraining and predicting future global N2O emissions. Efficient N2O removal, in addition to dissolved nitrogen removal, should be an essential part of water quality control in WWTPs.

Occurrence of emerging contaminants in three river basins impacted by wastewater treatment plant effluents: Spatio-seasonal patterns and environmental risk assessment

The concern on the fate and distribution of contaminants of emerging concern (CECs) is a burning topic due to their widespread occurrence and potential harmful effects. Particularly, antibiotics have received great attention due to their implications in antimicrobial resistance occurrence. The impact of wastewater treatment plants (WWTP) is remarkable, being one of the main pathways for the introduction of CECs into aquatic systems. The combination of novel analytical methodologies and risk assessment strategies is a promising tool to find out environmentally relevant compounds posing major concerns in freshwater ecosystems impacted by those wastewater effluents. Within this context, a multi-target approach was applied in three Spanish river basins affected by different WWTP treated effluents for spatio-temporal monitoring of their chemical status. Solid phase extraction followed by ultra-high-performance liquid chromatography were used for the quantification of a large panel of compounds (n = 270), including pharmaceuticals and other consumer products, pesticides and industrial chemicals. To this end, water samples were collected in four sampling campaigns at three locations in each basin: (i) upstream from the WWTPs; (ii) WWTP effluent discharge points (effluent outfall); and (iii) downstream from the WWTPs (500 m downriver from the effluent outfall). Likewise, 24-h composite effluent samples from each of the WWTPs were provided in all sampling periods. First the occurrence and distribution of these compounds were assessed. Diverse seasonal trends were observed depending on the group of emerging compounds, though COVID-19 outbreak affected variations of certain pharmaceuticals. Detection frequencies and concentrations in effluents generally exceeded those in river samples and concentrations measured upstream WWTPs were generally low or non-quantifiable. Finally, risks associated with maximum contamination levels were evaluated using two different approaches to account for antibiotic resistance selection as well. From all studied compounds, 89 evidenced environmental risk on at least one occasion in this study.

Evaluation of the Environmental Impact and Energy Utilization Efficiency of Wastewater Treatment Plants in Tumen River Basin Based on a Life Cycle Assessment + Data Envelopment Analysis Model

The environmental impacts from energy consumption account for a high percentage of the environmental impacts of wastewater treatment plants (WWTPs) throughout their life cycle; therefore, controlling energy use in WWTPs could bring substantial benefits to the environment. In this study, according to the different percentages of electricity generation from renewable energy compared to fossil energy, the global warming, acidification, eutrophication, human toxicity, and photochemical smog, the environmental impacts of WWTP operation were considered. Furthermore, to explore a more sustainable way of operating WWTPs under the “dual-carbon” strategic decision, the environmental impacts and energy utilization efficiency of different power allocation scenarios at present and in the next 40 years were compared based on the LCA+DEA integrated model. The study revealed that in scenarios 1–5, as the proportion of renewable energy power generation gradually increased, all LCA results showed a gradual decrease, of which GWP decreased by 83.32% and human toxicity decreased by 93.34%. However, in scenarios 2–5, the contribution ratio (proportion) of gas and electricity to GWP and POCP gradually increased, reaching 77.11% and 59.44%, respectively, in scenario 5. The contribution ratio (proportion) of biomass generation to AP and EP gradually increased as well, reaching 65.22% and 68.75%, respectively, in scenario 5. Meanwhile, the combined technical efficiency in energy utilization in the five scenarios showed a decreasing trend; only scenario 1 was fully efficient, and the combined efficiency was 1. The values of combined technical efficiency in scenarios 2, 3, 4, and 5 gradually decreased and were 0.7386, 0.4771, 0.2967, and 0.1673, respectively. This study discusses whether the use of renewable energy in place of fossil energy power elicits an environmental impact in WWTPs. We explore the feasibility of achieving energy savings and emission reductions in WWTPs within the Tumen River Basin, to provide a theoretical basis for their sustainable development.

Potential Linkage between Heavy Metal Pollution Risk Assessment and Dissolved Organic Matter Spectra in the WWTPs-River Integrated Area-Case Study from Ashi River.

Direct sewage discharge can cause severe damage to the water environment of the river. However, the impacts of dissolved organic matter (DOM) in the discharge on the original pattern of DOM and the distribution of heavy metals (HMs) in the river are little known. How to monitor such areas in a long-term and systematic manner also needs to be urgently addressed. In this paper, we characterized the DOM of the sediments in the WWTPs (wastewater treatment plants)-river integrated zone by ultraviolet-visible absorption spectroscopy (UV-vis), three-dimensional excitation-emission matrix (3D-EEM) combined with parallel factor (PARAFAC) method. The effects of WWTP on receiving waters were investigated, and the potential link between DOM and HM pollution was explored. Hg (Igeo: 3.94 ± 0.65; EF: 44.83 ± 31.11), Cd (Igeo: 1.81 ± 0.69; EF: 8.02 ± 2.97), Cu (Igeo: 1.61 ± 0.83; EF: 6.85 ± 2.37), Zn (Igeo: 1.55 ± 0.54; EF: 7.24 ± 3.58), and Ni (Igeo: 1.46 ± 0.56; EF: 6.12 ± 1.99) in rivers were the primary risk sources of HM. The combined pollution risk indicates that the WWTPs-river integrated area is in a high pollution risk state. Moreover, α(254) has a significant correlation with pollution indicators and can be used as a proxy indicator. These results help to understand better the impact of WWTPs on receiving water bodies and the potential connection between DOM and HM pollution and provide new ideas for monitoring the water environment in highly polluted areas.

Distribution of Antibiotic Resistance in a Mixed-Use Watershed and the Impact of Wastewater Treatment Plants on Antibiotic Resistance in Surface Water.

The aquatic environment has been recognized as a source of antibiotic resistance (AR) that factors into the One Health approach to combat AR. To provide much needed data on AR in the environment, a comprehensive survey of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs), and antibiotic residues was conducted in a mixed-use watershed and wastewater treatment plants (WWTPs) within the watershed to evaluate these contaminants in surface water. A culture-based approach was used to determine prevalence and diversity of ARB in surface water. Low levels of AR Salmonella (9.6%) and Escherichia coli (6.5%) were detected, while all Enterococcus were resistant to at least one tested antibiotic. Fewer than 20% of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (17.3%) and carbapenem-resistant Enterobacteriaceae (CRE) (7.7%) were recovered. Six ARGs were detected using qPCR, primarily the erythromycin-resistance gene, ermB. Of the 26 antibiotics measured, almost all water samples (98.7%) had detectable levels of antibiotics. Analysis of wastewater samples from three WWTPs showed that WWTPs did not completely remove AR contaminants. ARGs and antibiotics were detected in all the WWTP effluent discharges, indicating that WWTPs are the source of AR contaminants in receiving water. However, no significant difference in ARGs and antibiotics between the upstream and downstream water suggests that there are other sources of AR contamination. The widespread occurrence and abundance of medically important antibiotics, bacteria resistant to antibiotics used for human and veterinary purposes, and the genes associated with resistance to these antibiotics, may potentially pose risks to the local populations exposed to these water sources.

Antibiotic resistance indicator genes in biofilm and planktonic microbial communities after wastewater discharge.

The spread of bacteria with antibiotic resistance genes (ARGs) in aquatic ecosystems is of growing concern as this can pose a risk of transmission to humans and animals. While the impact of wastewater treatment plant (WWTP) effluent on ARG abundance in surface waters has been studied extensively, less is known about the fate of ARGs in biofilms. The proximity and dense growth of microorganisms in combination with the accumulation of higher antibiotic concentrations in biofilms might render biofilms a reservoir for ARGs. Seasonal parameters such as water temperature, precipitation, and antibiotic concentrations should be considered as well, as they may further influence the fate of ARGs in aquatic ecosystems. Here we investigated the effect of WWTP effluent on the abundance of the sulfonamide resistance genes sul1 and sul2, and the integrase gene intI1 in biofilm and surface water compartments of a river in Germany with a gradient of anthropogenic impact using quantitative PCR. Furthermore, we analyzed the bacterial community structure in both compartments via 16S rRNA gene amplicon sequencing, following the river downstream. Additionally, conventional water parameters and sulfonamide concentrations were measured, and seasonal aspects were considered by comparing the fate of ARGs and bacterial community diversity in the surface water compartment between the summer and winter season. Our results show that biofilm compartments near the WWTP had a higher relative abundance of ARGs (up to 4.7%) than surface waters (<2.8%). Sulfonamide resistance genes were more persistent further downstream (>10 km) of the WWTP in the hot and dry summer season than in winter. This finding is likely a consequence of the higher proportion of wastewater and thus wastewater-derived microorganisms in the river during summer periods. We observed distinct bacterial communities and ARG abundance between the biofilm and surface water compartment, but even greater variations when considering seasonal and spatiotemporal parameters. This underscores the need to consider seasonal aspects when studying the fate of ARGs in aquatic ecosystems.

The impact of wastewater treatment plants on aquatic ecosystems

The impact of wastewater treatment plants on aquatic ecosystems

Spatio-seasonal patterns of the impact of wastewater treatment plant effluents on antibiotic resistance in river sediments

There is a growing concern about the risk of antibiotic resistance emergence and dissemination in the environment. Here, we evaluated the spatio-seasonal patterns of the impact of wastewater treatment plant (WWTP) effluents on antibiotic resistance in river sediments. To this purpose, sediment samples were collected in three river basins affected by WWTP effluents in wet (high-water period) and dry (low-water period) hydrological conditions at three locations: (i) upstream the WWTPs; (ii) WWTP effluent discharge points (effluent outfall); and (iii) downstream the WWTPs (500 m downriver from the effluent outfall). The absolute and relative abundances of 9 antibiotic resistance genes (ARGs), 3 mobile genetic element (MGE) genes, and 4 metal resistance genes (MRGs) were quantified in sediment samples, as well as a variety of physicochemical parameters, metal contents, and antibiotic concentrations in both sediment and water samples. In sediments, significantly higher relative abundances of most genes were observed in downstream vs. upstream sampling points. Seasonal changes (higher values in low-water vs. high-water period) were observed for both ARG absolute and relative abundances in sediment samples. Chemical data revealed the contribution of effluents from WWTPs as a source of antibiotic and metal contamination in river ecosystems. The observed positive correlations between ARG and MGE genes relative abundances point out to the role of horizontal gene transfer in antibiotic resistance dissemination. Monitoring plans that take into consideration spatio-temporal patterns must be implemented to properly assess the environmental fate of WWTP-related emerging contaminants in river ecosystems.

Evaluation of sedimentary bacterial community dynamics and contamination assessment of lower Des Plaines River

Urban rivers often contain elevated concentrations of contaminants such as organic pollutants and heavy metals which can be amplified in lotic ecosystems receiving effluents from wastewater treatment plants (WWTP). However, the impact of WWTPs on the microbial parameters of the urban river sediments has not been well documented compared to urban surface water. Collecting sediment samples at five different locations over a 9,000 m transect during four sampling periods, we investigated spatiotemporal variations of microbial parameters in sediments of lower Des Plaines River; the largest effluent-dominated stream in the United States and the effects of sediment physicochemical properties on the variations were explored. We reported reduced microbial biomass, CFUs, and distinct bacterial communities at the WWTP outfall compared to other sites, indicating that WWTP effluents have the potential to moderate bacterial community structure. Seasonal variations in the sedimentary bacterial community structure were evident regardless of the spatial variations imposed by the effluents. Our community-level physiological profiling of the sedimentary bacterial community structure indicated that temperature was more important than water chemistry, whereas total microbial biomass by phospholipid phosphate analysis responded to the influences of both temperature and water chemistry. Metal concentrations showed values that fall within the “fair” to “very poor” range of biological conditions outlined by the Midwest Biodiversity Institute. We posit that the increased sediment metal loads select for metal-tolerant microorganisms that help to maintain microbial biomass. In the spring, sequencing of bacterial 16S rRNA genes revealed significant effects of effluent on bacterial community composition at the WWTP outfall, showing increases in abundances of Caldilinea, Candidatus, Allochromatium, Sulfuritalea, and Nitrospira sequences, linked to anthropogenic inputs from WWTP effluents. Given that human dependence on effluent-dominated ecosystems for water resources will increase with rapidly increasing urbanization, studies focusing on remediation and policy changes are dire to develop effective management of existing urban rivers.

Effect of 45 full-scale WWTPs on tropical receiving water bodies in Brazil by partial least squares-discriminant analysis

Abstract Treated wastewater may affect water quality and thereby significantly alter physicochemical and biological water quality parameters. The impact of wastewater treatment plants (WWTPs) on receiving water bodies is a multivariate problem. In this study, we investigated the effect of 45 full-scale WWTPs on tropical receiving water bodies in Mato Grosso do Sul State, Brazil. Most of the Pantanal wetland area lies within Mato Grosso do Sul State, thus representing a region of great hydrological relevance. Partial least squares-discriminant analysis (PLS-DA) was employed to discriminate samples collected at four WWTPs monitoring sites: influent, final effluent, upstream, and downstream of the discharges. The model demonstrated excellent accuracy when discriminating the influent from the effluent samples, but poor accuracy when discriminating upstream and downstream samples, indicating the high dilution capacity of the receiving water bodies as a critical factor in the water resources management. The results demonstrate the great potential of the methodology for better water resources management, which can be used in even more complex WWTP databases, allowing the assessment of effluent disposals' impacts in detail. It is recommended to use this methodology in water-limited regions to determine the effect of disposals in areas with different characteristics.

Impact of wastewater treatment plants on microbiological contamination for evaluating the risks of wastewater reuse

BackgroundWastewater reuse represents a promising alternative source of water supply considering the water scarcity related to climate change. However, if not adequately treated, wastewater represents a source of microbiological health risk. The purpose of this work was to investigate the role of wastewater treatment on microbiological contamination by evaluating the possible risks associated with wastewater effluent reuse, taking into account new EU legislation (2020/741) on minimum requirements for water reuse. E. coli that produce Shiga toxins (STEC) and thermotolerant Campylobacter were monitored using an enrichment step associated with specific PCR, while Salmonella spp. and Legionella were detected with both cultural and molecular methods (PCR and q-PCR, respectively). Culture method was also used for the enumeration of different microbial indicators. The bacteria detection was compared in different wastewater plants with membrane bioreactor (MBR) system or with disinfection step with chlorine dioxide (ClO2). Moreover a comparison between molecular and culture methods was discussed.ResultsThe results obtained showed good abatement performance for WWTPs equipped with MBR. The high concentrations of E. coli (range between 0.88 and 5.21 Log MPN/100 mL) and contamination by Salmonella spp. in effluent disinfected with ClO2 (17% of samples) showed the need to control the quality of this effluent. In addition, despite the absence of Legionella spp. with the culture method required by EU regulation, high concentrations of Legionella spp. (range between 2 and 7 log GU/L) and the presence of Leg. pneumophila with qPCR (15% of samples) highlight the need to carry out further investigations for reuse associated with aerosol formation (e.g. spray irrigation in agriculture).ConclusionsThe results obtained underline that the MBR technology can be suitable for wastewater reuse applications allowing to achieve the requirement proposed by the new European legislation. More attention should be given to wastewater reuse of effluents treated with ClO2. The use of the molecular methods for pathogens detection in wastewater could allow a more precautionary risks estimation associated with reuse. The overall results highlight that an evaluation of the effectiveness of the wastewater treatments is required for the prevention of a possible risk to public health.

OPERATIONAL EFFICIENCY AND ENVIRONMENTAL IMPACT OF WASTEWATER TREATMENT PLANTS IN LITHUANIAN RURAL AREAS

The aim of the paper was to determine the operational efficiency and environmental impact of five small wastewater treatment plants (WWTPs) in Ukmergė district. The efficiency of these WWTPs, reconstructed by applying the same vertical flow labyrinth technology was calculated according to the most important pollution indicators: biochemical oxygen consumption in 7 days (BOD7), total phosphorus (TP) and total nitrogen (TN) in period 2017-2020. It was found that the lowest operational efficiency of Taujėnai wastewater treatment plant was according to BOD7 (94-96%). The lowest treatment efficiency of total nitrogen was determined in Dainava WWTP (88-95%). The highest treatment efficiency according to total phosphorus was in Šventupė WWTP (86-92%), the lowest in Žemaitkiemis WWTP (72-85%). In order to evaluate the impact of wastewater treatment plants on the environment, their Life Cycle Assessment (LCA) was performed. Sludge from wastewater treatment process has been found to have the highest environmental impact and fuel consumption for transport the lowest. Of the five wastewater treatment plants examined, the Vidiškiai wastewater treatment plant has the largest impact on the environment, and Šventupė WWTP has the lowest.

Review of Methods for Assessing the Impact of WWTPs on the Natural Environment

Environmental management in facilities such as wastewater treatment plants (WWTPs) allows for the implementation of the Deming cycle, and thus the constant improvement of the mitigation of the environmental impact. The correct diagnosis of the current state of functioning of the WWTPs, the identification of aspects that may have a measurable impact on the environment, and their assessment are of key importance. The article discusses the possible causes of the impact of WWTPs on the natural environment. Among other problems, such issues as energy consumption, noise and the formation of bioaerosols and odor nuisances were taken into account. Different ways of assessing the impact of wastewater treatment plants on the environment were collated, taking into account the need to assess not only the technological process itself but also the buildings during their use. The results of methods for assessing the environmental impact of wastewater treatment plants in selected countries were also compared.

Comparison of life cycle toxicity assessment methods for municipal wastewater treatment with the inclusion of direct emissions of metals, PPCPs and EDCs

The occurrence of various micropollutants such as pharmaceuticals personal care products, endocrine disrupting chemicals (PPCPs/EDCs) and metals in municipal wastewater, and their poor removal efficiencies can lead to toxicity impact on humans, and freshwater and terrestrial ecosystems. Life cycle assessment is an efficient and effective tool to evaluate the environmental impact of wastewater treatment plants, but guidelines for toxicity assessment are lacking due to the complexity. This study aims to evaluate both life cycle inventory by including metals and PEC, and life cycle toxicity assessment (LCIA) methods namely CML-IA, Recipe, USEtox, EDIP 2003 and IMPACT 2002+ in midpoint category with a large centralised wastewater treatment plant in Malaysia as a case study. The removal efficiencies of metals and PPCPs/EDCs in the wastewater ranged from 9% to 99% and no clear patterns were found about occurrence and removal efficiencies of metals and PPCPs/EDCs in developing and developed countries. The inclusion of metals and PPCPs/EDCs in effluent resulted in 76% increase in freshwater ecotoxicity potential (FEP) and 88% increase in terrestrial ecotoxicity potential (TEP) while only 4% increase in human toxicity potential (HTP). The results indicate the importance of including direct emissions such as metals and PPCPs/EDCs even in low-strength municipal wastewater for environmental toxicity assessment. The comparison of five LCIA methods suggests that HTP assessment is more challenging due to inconsistency between five LCIA methods while CML-IA, Recipe, and IMPACT 2002+ achieved consistent human toxicity and ecotoxicity assessment results in the WWTP. The results highlight the importance of sampling and inclusion of metals and PPCPs/EDCs data especially prioritised micropollutants for life cycle toxicity assessment and recommends LCIA methods for ecotoxicity assessment of WWTPs in the current scientific development situation on toxicity studies, which can provide guidance to researchers for life cycle toxicity assessment of wastewater treatment.

Employing complementary multivariate methods for a designed nontarget LC-HRMS screening of a wastewater-influenced river

Environmental pollution issues, such as the impact of wastewater treatment plants (WWTPs) to contaminate the recipient waters, are multivariate problems in which several variables with varying correlation values contribute. Chemometrics-based methods can play a critical role to study the occurrence and fate of contaminants of emerging concern (CECs) in an environmental pollution question. This study performed nontarget screening (NTS) with liquid chromatography-high resolution mass spectrometry (LC-HRMS) for the investigation of pollution patterns of river water samples affected by the effluent of a WWTP (upstream/downstream) at three sampling times. The complex data sets collected in a designed experiment were analyzed using the ROIMCR approach, using data selection from MS regions of interest (ROI). Then, multivariate curve resolution alternating least-squares (MCR-ALS) was applied for simultaneous resolution of 18 upstream/downstream river water samples. The resolved and cleaned matrix of peak areas were subjected to group-wise ANOVA-simultaneous component analysis (GASCA) for interpretation of the variations induced by location and time factors in a sparse principal component analysis way and to uncover the groups of pollutants co-occurring in the environment. The resolved groups of significant features based on sampling site factor were compared with the prioritized features using partial least squares-discriminant analysis (PLS-DA) least squares-discriminant analysis ures using partial least-squares-discriminant analysis (PLS-DA). Here, we focused on the environmental relevance of groups of compounds with significant variations for a few tentatively identified contaminants. This study clearly shows that employing complementary chemometric tools for NTS can improve the current knowledge on exposure trends of CECs in water bodies for further investigation.

Impact of treated sewage effluent on the bacterial community composition in an intermittent mediterranean stream

Water quality monitoring is essential to safeguard human and environmental health. The advent of next-generation sequencing techniques in recent years, which allow a more in-depth study of environmental microbial communities in the environment, could broaden the perspective of water quality monitoring to include impact of faecal pollution bacteria on ecosystem. In this study, 16 S rRNA amplicon sequencing was used to evaluate the impact of wastewater treatment plant (WWTP) effluent on autochthonous microbial communities of a temporary Mediterranean stream characterized by high flow seasonality (from 0.02 m3/s in winter to 0.006 m3/s in summer).Seven sampling campaigns were performed under different temperatures and streamflow conditions (winter and summer). Water samples were collected upstream (Upper) of the WWTP, the secondary effluent (EF) discharge and 75 m (P75) and 1000 m (P1000) downstream of the WWTP.A total of 5,593,724 sequences were obtained, giving rise to 20,650 amplicon sequence variants (ASV), which were further analysed and classified into phylum, class, family and genus. Each sample presented different distribution and abundance of taxa. Although taxon distribution and abundance differed in each sample, the microbial community structure of P75 resembled that of EF samples, and Upper and P1000 samples mostly clustered together. Alpha diversity showed the highest values for Upper and P1000 samples and presented seasonal differences, being higher in winter conditions of high streamflow and low temperature.Our results suggest the microbial ecology re-establishment, since autochthonous bacterial communities were able to recover from the impact of the WWTP effluent in 1 km. Alpha diversity results indicates a possible influence of environmental factors on the bacterial community structure. This study shows the potential of next-generation sequencing techniques as useful tools in water quality monitoring and management within the climate change scenario.

Tool for selecting indicator substances to evaluate the impact of wastewater treatment plants on receiving water bodies

The elimination of organic micropollutants (OMPs) from wastewater could in future become mandatory for operators of wastewater treatment plants (WWTPs). Indicator substances are a great help and a cost-efficient way in monitoring the pollution of water bodies with OMPs caused by the discharge of WWTPs. However, with the still increasing number of OMPs in our environment, the selection of suitable indicator substances presents a challenge. A concept was developed to help identify representative indicator substances. The derived indicator substances are not only used to assess water pollution, but can also be used to calculate elimination efficiencies of WWTPs. In the present investigations, the indicator substances were used to evaluate the reduction of OMPs in the water body on the basis of the expansion of a WWTP with an ozonation plant. The transferability of the tool was verified with a second WWTP. Furthermore, the impact of the number of measurements was analysed via statistical combinatorics. With the tool, 36 substances were classified, leading to the identification of 9 suggested indicator substances. Among them ibuprofen and diclofenac attracted attention due to their ecotoxicological relevance. Detailed data analyses were carried out using principal component analysis (PCA) and loads.

The Chlorination Impact of Wastewater Treatment Plants in the Danube River

An appropriate appraisal of the water quality parameters has an essential contribution in identification of main pollution factors in a certain region. In Romania, the lower course of Danube River Basin covers more than 1,075 kilometres and a significant percentage of the population lives in this area and depends on the Danube for potable water, industry, agriculture, and transport. The biodiversity, species and habitats, is markedly significant, taking in account that the Danube is the largest uninterrupted wetland area in the world and one of the last relatively undisturbed regions of Europe. The main focus of this article is to analyze the capability of chlorine removal in the municipal wastewater treatment plants in five counties of Romania, starting from 2013 to 2017. The five years average of influent fluctuates from 77.56 mg/dm3 to 111.03 mg/dm3 comparing with 82.94 mg/dm3 and 116.29 mg/dm3 the average of effluent. It should be specified that the limit imposed by the European legislation is 500 mg/dm3. Even if the measured values are below a quarter of the imposed limit, chlorinated wastewaters can be poisonous and may have a harmful impact on aquatic flora and fauna that are exposed to them, and consequently, that chlorination dechlorination might not be appropriate treatment approach for the protection of receiving waters.

Life Cycle Assessment of Upgrading Primary Wastewater Treatment Plants to Secondary Treatment Including a Circular Economy Approach

Although significant progress has been achieved in the field of environmental impact assessment in many engineering disciplines, the impact of wastewater treatment plants has not yet been well integrated. In light of this remarkable scientific progress, the outputs of the plants as treated water and clean sludge have become potential sources of irrigation and energy, not a waste. The aim of this study is to assess the environmental impacts of upgrading the wastewater treatment plants from primary to secondary treatment. The Lifecycle Assessment Framework (ISO 14040 and 14044) was applied using GaBi Software. Abu Rawash wastewater treatment plant (WWTP) has been taken as a case study. Two scenarios were studied, Scenario 1 is the current situation of the WWTP using the primary treatment units and Scenario 2 is upgrading the WWTP by adding secondary treatment units. The study highlighted the influence and cumulative impact of upgrading all the primary WWTPs in Egypt to secondary treatment. With the high amount of energy consumed in the aeration process, energy recovery methods were proposed to boost the circular economy concept in Abu Rawash WWTP in order to achieve optimal results from environmental and economic perspectives.