Upgrading Of Wastewater Treatment Plants Research Articles

Coupling hydrological and sanitation datasets to simulate wastewater-derived contamination in European rivers: model development and calibration

Wastewater treatment plant (WWTP) discharges of microcontaminants negatively impact freshwater streams, underscoring the need for accurately mapping wastewater-derived contamination in water bodies across Europe (EU). In this study, we present a fast and open-source code for a microcontaminants fate and transport (MFT) model, capable of simulating contamination at a high resolution (15 arc second scale) across the EU. The model was developed using the best publicly available hydrological (HydroSHEDS) and sanitation (UWWTD) datasets and was rigorously calibrated, with a goodness of fit of 77.5% as measured by the . Importantly, the model demonstrated the ability to predict wastewater-derived contamination in water bodies, making it a valuable tool for planning the upgrade of WWTPs and improving the ecological condition of freshwater streams in the EU.

Environmental Impact Analysis and Carbon Emission Reduction Pathways by Upgrading Wastewater Treatment Plant: A Case Study of Upgrading Project at a Wastewater Treatment Plant in Dongguan, China

The potential environmental impact and increased operational costs associated with the upgrading and renovation of sewage treatment plants are acknowledged. This study employs the upgrading and expansion project of a municipal sewage plant in Dongguan City, Guangdong Province, as a case study. Utilizing the principles and methods of the Life Cycle Assessment (LCA), a comprehensive assessment of the environmental benefits during the upgrading and renovation process of the sewage treatment plant, is conducted and targeted solutions are proposed. The research findings indicate that upgrading and renovating sewage treatment plants can significantly augment the adverse environmental effects of such facilities. Therefore, this study strategically proposes measures such as the utilization of clean energy, sludge resource utilization, and recycled water use as carbon emission reduction pathways. Through calculations, it is demonstrated that the utilization of clean energy and sludge resource can respectively reduce electricity consumption by 12.41% and 59.06%. Concurrently, recycled water use can lead to a reduction of 68.65% in carbon emissions, thereby markedly enhancing positive environmental outcomes.

Conflict between urbanization and water environmental protection: Lessons from the Xiangjiang River Basin in China

China, the largest developing country, has experienced rapid urbanization since its reform and opening-up. However, the increasing pollution load from urban areas has deteriorated urban river water quality, contradicting the concept of sustainable and green development promoted by the Chinese government. This situation elucidates governmental shortcomings in systematic environmental protection. Our study revealed that the current wastewater treatment plant (WWTP) discharge standards in urban areas are insufficient for attaining the desired urban river water quality and thus intensify the conflict between urbanization and water environmental protection. As urbanization continues, the urban population will grow, further exacerbating pollution and conflict. Our focus was the Xiangjiang River basin in Zunyi, a typical urbanized city in China. Using a validated one-dimensional mathematical model, we compared the water quality in the Xiangjiang River between current and upgraded WWTP discharge standards. The results showed that the water quality in the Xiangjiang River falls short of the standards, with more than 60 % of the river exceeding limits. However, upgrading WWTP discharge standards significantly reduces the proportion of river sections exceeding limits, with only 0.4 % exceeding standards during specific periods. This enhancement greatly improved the Xiangjiang River's water quality, aided in restoring the entire water environment in the basin, and supported water environmental protection goals. Our research findings offer crucial support for local governments in shaping comprehensive water environmental protection policies and insights for addressing similar environmental challenges caused by rapid urbanization in other developing regions.

Implication of self-organizing map, stable isotopes combined with MixSIAR model for accurate nitrogen control in a well-protected reservoir

Nitrogen pollution and eutrophication in reservoirs is a global environmental geochemical concern. Occasional algal blooms still exist in reservoirs that have undergone pollution treatment. The lack of quantitative evidence of nitrogen sources and fate limits long-term stable ecological safety management. This work applied an approach integrated zonal mapping, stable isotopes (δ18OH2O, δ15Nnitrate, δ18Onitrate, and δ13C-DIC) and a Bayesian isotope model to analyze regional and seasonal differences in the contribution and sources of nitrogen to a well-protected reservoir. The values of δ18Onitrate and the positive relationship between NO3− and δ13C-DIC suggested that nitrification was the primary NO3− production in the rivers. While Denitrification was present at only a few sites. Results of the MixSIAR model coupled the NO3−/Cl− indicator revealed that the domestic sewage contributed high riverine NO3− loading (68.6 ± 10.6 %) in the dry season. In the wet season, the main nitrate sources of upper watershed were ammonia and carbamide fertilizers (47.5 % and 40.3 %). While the domestic sewage was still the major contributor of downstream region (a dense residential area), indicating possible problems with rainwater and sewage drainage networks. The results implied that the colleting and treatment of sewages were the priority in downstream region, and non-point source pollution control and wastewater treatment plant upgrading were essential to control nitrate pollution in the two upstream regions. These findings provide new insights into precise nitrogen pollution traceability and identification of treatment priorities in the sub-region, and promote the management other well-protected watershed in similar need of further nitrogen contamination control.

Municipal wastewater for energy generation: a favourable approach for developing nations

This study focuses on understanding municipal wastewater (MWW) constituents and assessing technological options to harness the energy content of wastewater in developing countries. There are numerous research studies related to water treatment technologies and wastewater energy value. However, it remains to be seen which perspectives actually make technology adoption feasible. This study explores and presents the potential for some viable and innovative MWW treatment plant (WWTP) systems as a paradigm shift towards resource recovery, energy neutrality and the production of renewable energy by WWTPs. Various cost-effective opportunities related to operational strategies, plant redesign and the upgrading of current WWTPs that can foster self-reliant communities were visualised. Thermal and chemical pretreatments, sequential batch reactors, anaerobic membrane fluidised bioreactors, ammonia-based aeration control and combined heat and power systems can collectively contribute to energy recovery by WWTPs, ranging from 85 to 111%. The study suggests that upgrading the system to become an energy self-reliant water treatment system outweighs the multimode costs associated with health and ecological damages by reducing diseases, pollution and poor productivity regimes.

Integrated control strategy for dual sludge ages in the high-concentration powder carrier bio-fluidized bed (HPB) technology: Enhancing municipal wastewater treatment efficiency

The high-concentration powder carrier bio-fluidized bed (HPB) technology is an emerging approach that enables on-site upgrading of wastewater treatment plants (WWTPs). HPB technology promotes the formation of biofilm sludge with micron-scale composite powder carriers as the core and suspended sludge mainly composed of flocs surrounding the biofilm sludge. This study proposed a novel integrated strategy for assessing and controlling the sludge ages in suspended/bio-film activated sludge supported by micron-scale composite powder carrier. Utilizing the cyclone unit and the corresponding theoretical model, the proposed strategy effectively addresses the sludge ages contradiction between denitrifying bacteria and polyphosphate-accumulating organisms (PAOs), thereby enhancing the efficiency of municipal wastewater treatment. The sludge age of the suspended (25 d) and bio-film (99 d) sludge, calculated using the model, contribute to the simultaneous removal of nitrogen and phosphorus. Meanwhile, the model further estimates distinct contributions of suspended and bio-film sludge to chemical oxygen demand (COD) and total nitrogen (TN), which are 55% and 42% for COD, 20% and 57% for TN of suspended sludge and bio-film sludge, respectively. This suggests that the contribution of suspended sludge and bio-film sludge to COD and TN removal efficiency can be determined and controlled by the operational conditions of the cyclone unit. Additionally, the simulation values for COD, ammonia nitrogen (NH4+-N), TN and total phosphorus (TP) closely align with the actual values of WWTPs over 70 days (p < 0.001) with the correlation coefficients (R2) of 0.9809, 0.9932, 0.9825, and 0.837, respectively. These results support the theoretical foundation of HPB technology for simultaneous nitrogen and phosphorus removal in sewage treatment plants. Therefore, this model serves as a valuable tool to guide the operation, design, and carrier addition in HPB technology implementation.

Simultaneous enhanced removal of pharmaceuticals and hormone from wastewaters using series combinations of ultra-violet irradiation, bioremediation, and adsorption technologies

Pharmaceuticals and hormones presence in effluent of conventional municipal wastewater treatment plants (WWTPs) have been widely reported. Medicinal mushrooms such as Ganoderma species and bentonite clay were recently found to have promising results in wastewater treatment with potential advantages in the removal of pharmaceuticals. Here we investigated a hybrid treatment comprising of three separate processes (no chemicals) i.e., UV irradiation, biological, adsorption (bentonite + dolomite) in a series to enhance the simultaneous removal pharmaceuticals and hormone from wastewaters (real and synthetic). In this study, fungal species Ganoderma lucidum (GLSB) and Ganoderma neo-japonicum (GJSG) are used separately in bioreactors. The work investigated removal efficiencies of four (4) pharmaceuticals and a hormone. The results showed that all investigated pharmaceuticals and hormone were removed in hybrid treatment during 54.5 h treatment. Both GLSB and GJSG reactor series treatments achieved maximum removal in both synthetic and real domestic wastewater. Overall, this study provides promising suggestions for the upgrade and design of WWTPs to simultaneous complete removal of pharmaceuticals and hormone. Present study is a beginning for future development of sustainable tertiary hybrid treatment process in addition to existing WWTPs processes to completely remove the emerging pollutants.

Assessing impacts of municipal wastewater treatment plant upgrades on bacterial hazard contributions to the receiving urban river using SourceTracker

Upgrading municipal wastewater treatment plants (MWTPs) has been implemented in many megacities of China to reduce the discharges of nutrients and other pollutants and improve water quality of highly urbanized rivers. However, the contribution of MWTP discharge to bacterial hazards in the receiving rivers after upgrades has been largely unknown. In this study, high-throughput sequencing and shotgun metagenomics were applied to investigate the changes in the abundance, composition, potential risks, and contributions of bacteria and antibiotic resistance genes (ARGs) from effluent to receiving river after upgrading the third-largest MWTP in China with denitrification biofilters, ultrafiltration, ozonation, and disinfection processes. The annual loadings of total nitrogen and 27 types of pharmaceuticals were reduced by 42.4% ± 13.2% and 46.2% ± 15.4%, respectively. Bacterial biomass decreased from (3.58 ± 0.49) to (1.23 ± 0.27) × 107 16S rRNA gene copies/mL, and identified biomarkers in effluent and downstream shifted due to the adopted processes. Opportunistic pathogen bacteria downstream were also reduced. Although the relative abundance of total ARGs in MWTP effluent increased from 1.10 ± 0.02 to 2.19 ± 0.03 copies/16S rRNA gene after upgrades, that of total and high-risk ARGs downstream showed no significant difference. More importantly, the Bayesian-based SourceTracker method provided valuable insight by revealing that the contributions of MWTP discharge to downstream bacteria (from 44.2% ± 1.5%–31.4% ± 0.9%) and ARGs (from 61.2% ± 5.3%–47.6% ± 4.1%) were significantly reduced following the upgrades, indicating upgrading MWTP showed integrated benefits to the bacterial hazards in the receiving river. This study provides useful information for better control of bacterial hazard risks and operational strategy for the improvement of the urban aquatic ecosystem.

Upgrade of the biggest catalytic ozonation wastewater treatment plant in China: From pollution control to carbon reduction

Catalytic ozonation is a widely used effective technology in advanced treatment for the removal of refractory organics from wastewater. However, it is also a highly energy-consuming technology, usually accounting for 30%∼40% of the total electricity consumption of a wastewater treatment plant (WWTP). The O3 consumption per unit of COD removed (g-O3/g-COD) is usually higher than 1.5 g-O3/g-COD, and the total carbon emission from catalytic ozonation is usually higher than 393.12 kgCO2 e/m3 of wastewater. In this study, we investigated an energy reduction strategy for the biggest catalytic ozonation WWTP, from laboratory-scale experimentation to corresponding engineering application. Laboratory-scale experiments showed that the mass transfer rate of dissolved O3 to the catalyst surface is crucial for COD removal efficiency. To improve the efficiency of catalytic ozonation, adding effluent backflow is a simple method that can enhance the removal of extracellular polymeric substances (EPS) from the catalyst surface and promote surface exposure. In the pilot-scale experiment (48 m3/d), when the backflow ratio increased from 0% to 100% (the optimal value), the proteins in EPS on the catalyst surface decreased significantly by 66.7%. The corresponding O3 consumption per unit of COD removed was reduced from 2.0 to 1.0 g-O3/g-COD. Furthermore, in the engineering application (52,000 m3/d) with a backflow ratio of 100%, the average effluent COD reduced from 52.0 to 43.3 mg/L, and the O3 consumption per unit of COD removed decreased from 0.98 to 0.69 g-O3/g-COD. In terms of carbon reduction, the indirect carbon emission reduction was approximately 3.0 × 103 t CO2 e/a. This study demonstrates the advantages of catalytic ozonation improvement and provides an engineering model of energy conversation and carbon emission reduction for over 35 similar WWTPs in China.

Enhanced nitrogen removal in the upgrading of municipal wastewater treatment plants by using zero-valent iron-modified biofilm carriers and clinoptilolite-modified biofilm carriers

A municipal wastewater treatment plant (WWTP) was initially operated as an anaerobic/aerobic (A/O) process and designed with the second grade of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002, Table S1). To upgrade for meeting the first grade A of the GB18918-2002 (COD, BOD5, NH4+-N, and TN are 50 mg/L, 10 mg/L, 5/8 mg/L, and 15 mg/L, respectively), the original process was reformed to a process of anaerobic/anoxic/aerobic-integrated free-moving biofilm and activated sludge (A2O-IFFAS) by filling zero-valent iron (ZVI)-modified biofilm carriers into anoxic bioreactors, as well as clinoptilolite-modified biofilm carriers into aerobic bioreactors. ZVI-modified biofilm carriers were used to enhance denitrification, whereas clinoptilolite-modified biofilm carriers were used to enhance nitrification. The effluent COD, BOD5, NH4+-N, and TN of the new process were 26 ± 14 mg/L, 7 ± 1 mg/L, 1.3 ± 0.2/4.7 ± 0.7 mg/L (summer/winter), and 12.1 ± 2.4 mg/L, respectively, and their removal efficiencies were 95 %, 96.1 %, 90.1 %/97.3 %, and 78.8 %, respectively, which meet the first grade A of the GB18918-2002. Compared with flocculent sludge, the biofilm of ZVI-modified biofilm carriers increased the relative abundance of Hyphomicrobium (facultative autotrophic denitrifying bacteria) from 1.5 % to 8.7 %, the biofilm of clinoptilolite-modified biofilm carriers increased the relative abundance of nitrifying bacteria (composed of Nitrosomonas and Nitrospira) from 4.0 % to 39.2 %. The case demonstrated that the A2O-IFFAS equipped with ZVI-modified biofilm carriers and clinoptilolite-modified biofilm carriers could significantly increase the nitrogen removal efficiency and had a good prospect for upgrading municipal WWTPs.

Mathematical modelling and comparative analysis of treatment technologies for upgrading wastewater treatment plants: A case study of biofilm reactors in El-Gouna, Egypt

In recent years, Moving Bed Biofilm Reactors (MBBRs) have been preferred to conventional processes with suspended biomass. The main reason for this preference is that it can achieve better removal efficiencies than conventional systems with smaller footprints. However, unlocking the full potential of MBBRs in large-scale WWTPs remains challenging in real life. In this study, the performance of three different treatment technologies, Extended Aeration Activated Sludge (EAAS), Hybrid Fixed Bed Biofilm Reactor (HFBBR), and Hybrid Moving Bed Biofilm Reactor (HMBBR), was investigated over a year in a WWTP located in El-Gouna, Egypt. The COD removal efficiencies of the three systems were comparable, with the EAAS achieving 93.5%, HFBBR 94%, and HMBRR 95%. Nevertheless, the NH4 removal efficiency of the EAAS was slightly lower (97.5%) than that of the HFBBR and the HMBBR, that achieved a removal efficiency of 98%. BioWin Software was able to mimic the real case of the WWTP of El-Gouna and critically defined all plant limitations and operational data. Different simulations were modeled to test the hydraulic and organic loading capacities of the three systems under different scenarios and operating conditions. The HMBBR system failed to withstand the increase in organic load because of the biomass sloughing effect and subsequently high TSS loads in the settlers. Biomass sloughing overloaded the settlers and lead to biomass loss in the effluent. As the settleability of the HMBBR sludge was significantly lower than for the HFBBR the TSS loss in the effluent happened that much earlier that the moving carrier application had an adverse effect contradicting with the primary purpose of adding media carriers. Model simulations and data analysis findings were used to recommend the most suitable configuration for upgrading an existing system using the attached growth technique with all kinetic parameters and operational conditions. The recommended configuration focuses mainly on the separation of plastic media in a compartment with a very low hydraulic retention time to absorb the incoming shock load.

Assessment of Wastewater Treatment Plant Upgrading with MBR Implementation.

Modernization of wastewater treatment plants is usually caused by their significant wear and changes in the flow rate and concentration of pollutants. If there is no initial data on the flow or pollution, their determination by calculation is required, which may lead to an increase in concentration. Within the study, the modernization of treatment facilities was estimated under conditions of reduced flow and increased pollution concentration. Calculations were carried out both manually and using the CapdetWorks software package. The focus was on secondary treatment facilities as the main element of the municipal wastewater treatment plant within their upgrade from only organic pollutants removal (plug-flow reactor) to removal of both organic pollutants and nutrients (technology of the University of Cape Town). The calculations of tank volumes have shown that the concentration of pollutants has a much greater impact on them than the change in flow, especially when improvement in the treatment quality is required. The study revealed that membrane sludge separation allows tanks to be reduced in volume by 1.5-2.5 times (depending on the value of mixed liquor suspended solids) in comparison with gravity separation, which means smaller capital costs. However, membrane application requires significant energy costs for membrane aeration. For the initial data of the study, the specific energy costs for aeration before the upgrade, after the upgrade (gravity separation), and after the upgrade (membrane separation) were 0.12 kWh/m3, 0.235 kWh/m3, and 0.3 kWh/m3, respectively. If the membrane lifetime is 10 years, membrane costs were determined to be 10-15% of the energy costs for aeration.

Hybrid granule-floc sludge distribution and its potential for upgrading a tropical continuous-flow wastewater treatment plant

Hybrid granule-floc sludge, previously overlooked, is now recognized for its efficient pollutant removal and reduced land footprint, offering potential for upgrading wastewater treatment plants (WWTPs). This study investigated its distribution in a tropical continuous-flow WWTP, focusing on microbial activities and community structure within granules and flocs. Results showed that 13.5 % of total sludge was granules, settling excellently with a sludge volume index ratio of 1.58 (5 min to 30 min) and three times faster than flocs. However, granules did not surpass flocs in nitrogen‑phosphorus removal activity and slow-growing bacteria enrichment, with similar relative abundances of nitrifying and anaerobic ammonia oxidation bacteria in granules (3.68 % and 0.015 %) and flocs (3.3 % and 0.008 %), respectively. These similarities may result from the absence of intensified granule retention, yielding a similar solids retention time as flocs. Based on these findings, a novel strategy involving intensified granule retention and flocs treatment was proposed for WWTP upgrades.

Advanced low-strength wastewater treatment, side-stream phosphorus recovery, and in situ sludge reduction with aerobic granular sludge

Modern paradigm has upgraded wastewater treatment plants (WWTPs) to water resources recovery facilities (WRRFs), where aerobic granular sludge (AGS) is a sewage treatment technology with promising phosphorus recovery (PR) potential. Herein, the AGS-based simultaneous nitrification, denitrification, and phosphorus removal coupling side-stream PR process (AGS-SNDPRr) was developed with municipal wastewater. Results revealed that AGS always maintained good structural stability, and pollutant removal was unaffected and effective after 40 days of anaerobic phosphorus-rich liquid extraction (fixed rate of 30%). The AGS-SNDPRr achieved a stable phosphorus recovery efficiency of 63.40%, and the side-stream PR further exaggerated in situ sludge reduction by 7.7–10%. Apart from responses of extracellular polymeric substances (EPS), the Matthew effect of typical denitrifying glycogen accumulating organisms (DGAOs) Candidatus_Competibacter up to 67.40% mainly contributed to enhanced performance of this new process. This study demonstrated a new approach for simultaneous advanced wastewater treatment, phosphorus recovery, and excess sludge minimization.

Carbon footprint analysis and comprehensive evaluation of municipal wastewater treatment plants under different typical upgrading and reconstruction modes

The issue of greenhouse gas (GHG) emissions resulting from the upgrading and reconstruction of municipal wastewater treatment plants (MWWTPs) along with improved water quality is receiving attention and research. There is an urgent need to explore the impact of upgrading and reconstruction on carbon footprint (CF) in order to address concerns that the upgrading and reconstruction will increase GHG emissions while improving water quality. Here we accounted for the CF of five MWWTPs in Zhejiang Province, China, before and after three different upgrading and reconstruction models - “Improving quality and efficiency” (“Mode I”), “Upgrading and renovation” (“Mode U”) and “Improving quality and efficiency plus Upgrading and renovation” (“Mode I plus U”). The upgrading and reconstruction was found to not necessarily result in more GHG emissions. In contrast, the “Mode I” had a more significant advantage in terms of CF reduction (1.82–12.6 % reduction in CF). Overall, the ratio of indirect emissions to direct emissions (indirect emissions/direct emissions) and the amount of GHG emitted per unit of pollutant removed (CFCOD、CFTN、CFTP) decreased, while both the carbon and energy neutral rates increased significantly (up to 33.29 % and 79.36 % respectively) after all three upgrading and reconstruction modes. In addition, the wastewater treatment efficiency and capacity are the main factors that affect the level of carbon emission. The results of this study can provide a calculation model that can be used for other similar MWWTPs during the upgrading and reconstruction processes. More importantly, it can provide a new research perspective as well as valuable information to revisit the impact of upgrading and reconstruction in MWWTPs on GHG emissions.

Synergetic effects of pyrrhotite and biochar on simultaneous removal of nitrate and phosphate in autotrophic denitrification system.

In the trend of upgrading wastewater treatment plants, developing advanced treatment technologies for more efficient nutrient removal is crucial. This study prepared a pyrrhotite-biochar composite (Fex Sy @BC) to investigate its potential for simultaneous removal of nitrate and phosphate under autotrophic denitrification conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were used to characterize the novel composite of Fex Sy @BC, which exhibited 9.2mg N/(L·d) NO3 - -N reduction rate, 97.3% N2 production, and 81.8mmol N/(kg·d) NO3 - -N material load with small solid/liquid ratio (0.008). The NO3 - -N removal with Fex Sy @BC was 1.2-2.2 times higher than that with pure iron sulfides or biochar or their mixtures, whereas the Δn(S)/Δn(N) of Fex Sy @BC was the lowest (1.80). Moreover, the PO4 3- -P reduction rate of Fex Sy @BC reached 3.23 mg P/(L·d), as high as that of pure pyrite or pyrrhotite. Thiobacillus was the most dominant denitrifying bacterium. Fex Sy @BC exhibited great promise for enhancing nutrient removal from secondary effluent without additional carbon source. PRACTITIONER POINTS: FexSy@BC enhanced nitrate and phosphate removal simultaneously. First-order kinetics and Monod model were fitted for denitrification with FexSy@BC. FexSy@BC had smaller molar ratio of sulfate release to nitrate removal. Thiobacillus was the dominant bacterium in FexSy@BC autotrophic denitrification. Synergistic effects on nutrients removal existed between biochar and pyrrhotite.

Study of the Influence of the Wastewater Matrix in the Adsorption of Three Pharmaceuticals by Powdered Activated Carbon.

The use of powdered activated carbon (PAC) as an absorbent has become a promising option to upgrade wastewater treatment plants (WWTPs) that were not designed to remove pharmaceuticals. However, PAC adsorption mechanisms are not yet fully understood, especially with regard to the nature of the wastewater. In this study, we tested the adsorption of three pharmaceuticals, namely diclofenac, sulfamethoxazole and trimethoprim, onto PAC under four different water matrices: ultra-pure water, humic acid solution, effluent and mixed liquor from a real WWTP. The adsorption affinity was defined primarily by the pharmaceutical physicochemical properties (charge and hydrophobicity), with better results obtained for trimethoprim, followed by diclofenac and sulfamethoxazole. In ultra-pure water, the results show that all pharmaceuticals followed pseudo-second order kinetics, and they were limited by a boundary layer effect on the surface of the adsorbent. Depending on the water matrix and compound, the PAC capacity and the adsorption process varied accordingly. The higher adsorption capacity was observed for diclofenac and sulfamethoxazole in humic acid solution (Langmuir isotherm, R2 > 0.98), whereas better results were obtained for trimethoprim in the WWTP effluent. Adsorption in mixed liquor (Freundlich isotherm, R2 > 0.94) was limited, presumably due to its complex nature and the presence of suspended solids.

EcoImprove: Revealing aquatic ecological effects of micropollutant discharge from municipal wastewater treatment plants

Micropollutants (MPs) discharged from municipal wastewater treatment plants are of great environmental concern due to their toxicities to aquatic organisms. Given the knowledge gaps on how MPs affect receiving aquatic ecosystems, we initiated the EcoImprove project to unravel the causal relationship between MP discharge and variation in biocommunity (especially microbial community) composition and function in receiving aquatic ecosystems. After integrating laboratory studies, field investigations, and flume simulation experiments from 2014 to 2021, we investigated how different MPs affect the growth and metabolic function of microbial species, developed several microbial indicators to evaluate the effects of MP discharge on receiving rivers, and evaluated the ecological benefits of municipal wastewater treatment plant upgrade on receiving aquatic ecosystems. Here, we summarize the main outcomes of the EcoImprove project and propose future research plans to deepen our understanding of the ecological impacts of anthropogenic activity.

Mitigating microbiological risks of potential pathogens carrying antibiotic resistance genes and virulence factors in receiving rivers: Benefits of wastewater treatment plant upgrade

Mitigating microbiological risks of potential pathogens carrying antibiotic resistance genes and virulence factors in receiving rivers: Benefits of wastewater treatment plant upgrade

Wild fish responses to wastewater treatment plant upgrades in the Grand River, Ontario

Municipal wastewater treatment plant (WWTP) effluent is one of several point sources of contaminants (nutrients, pharmaceuticals, estrogens, etc.) which can lead to adverse responses in aquatic life. Studies of WWTP effluent impacts on rainbow darter (Etheostoma caeruleum) collected downstream of WWTPs in the Grand River, Ontario have reported disruption at multiple levels of biological organization, including altered vitellogenin gene expression, lower levels of in vitro steroid production, and high frequency of intersex. However, major upgrades have occurred at treatment plants in the central Grand River over the last decade. Treatment upgrades to the Waterloo WWTP were initiated in 2009 but due to construction delays, the upgrades came fully on-line in 2017/2018. Responses in rainbow darter have been followed at sites associated with the outfall consistently over this entire time period. The treatment plant upgrade resulted in nitrification of effluent, and once complete there was a major reduction in effluent ammonia, selected pharmaceuticals, and estrogenicity. This study compared several key responses in rainbow darter associated with the Waterloo WWTP outfall prior to and post upgrades. Stable isotopes signatures in fish were used to track exposure to effluent and changed dramatically over time, corresponding to the effluent quality. Disruptions in in vitro steroid production and intersex in the darters that had been identified prior to the upgrades were no longer statistically different from the upstream reference sites after the upgrades. Although annual variations in water temperature and flow can potentially mask or exacerbate the effects of the WWTP effluent, major capital investments in wastewater treatment targeted at improving effluent quality have corresponded with the reduction of adverse responses in fish in the receiving environment.