Effluent Standards Research Articles

Performance and bacterial community analysis of a two-stage A/O-MBBR system with multiple chambers for biological nitrogen removal.

A two-stage anoxic/oxic (A/O)-moving bed biofilm reactor (MBBR) system with multiple chambers was established for municipal wastewater treatment. At the total hydraulic retention time (HRT) of 11.2h and nitrate recycling ratio of 1, the removal efficiencies reached 83.8%, 82.5%, and 77.8% for soluble chemical oxygen demand (SCOD), 98.0%, 97.5%, and 94.9% for ammonia nitrogen (NH4+-N), and 91.8%, 92.0%, and 87.7% for total inorganic nitrogen (TIN) in summer, autumn and winter, respectively. Biofilms with functional bacterial populations were formed in the pre-anoxic reactors, the pre-oxic reactors, the post-anoxic reactors and the post-oxic reactors of the two-stage A/O-MBBR system. The highest nitrification potential was found in the last oxic reactor of the first A/O-MBBR subsystem with the highest relative abundances of the functional genes including [EC:1.14.99.39] and [EC:1.7.2.6]). The highest denitrification potential was found in the post-anoxic reactors with the highest relative abundances of the functional genes including [EC:1.7.2.1], [EC:1.7.2.5] and [EC:1.7.2.4]. This work constructed an efficient municipal biological nitrogen removal technology to achieve high effluent nitrogen standards in winter, and investigated its working mechanism to provide a basis for its design and optimization.

축산폐수처리에 있어서 전처리 약품주입이 없는 친환경적인 HM공법의 특성에 관한 연구

This study was conducted for the purpose of using the HM method as basic data for livestock waste treatment facilities. As a result of analyzing the treatment characteristics of each process of the eco-friendly HM method and analyzing the effluent water treatment characteristics, the following conclusions were obtained. In the pretreatment process, the removal efficiency by centrifugation was found to be 59.1 %, TOC 55.2 %, SS 61.1 %, T-N 46.7 %, and T-P 38.0 % removed. In the analysis by process, the removal efficiency of water quality items of discharged water was high at BOD 97.7 %, TOC 99.0 %, SS 99.7%, T-N 98.2 %, and T-P 99.6 %. In order to analyze the water quality characteristics of the effluent water, the water quality standard items of the 120 m³/day treatment facility were analyzed as BOD 1.9 mg/L to 4.2 mg/L, COD 16.6 mg/L to 48.8 mg/L, SS 1.6 mg/L to 11.0 mg/L, T-N 8.400 mg/L to 38.030 mg/L, and T-P 0.051 mg/L to 0.644 mg/L. This resulted in a relatively high treatment rate due to a very high concentration of inflow water, and in all items, it was measured below the effluent water quality standard of the treatment facility installed by the livestock manure treatment company. According to the calculation of the cost of injecting coagulant and carbon source, which can be saved by the eco-friendly construction method without using chemicals, the cost of a daily treatment amount of 120 m3/day is reduced by about 130 million won per year.

Microalgal-bacterial consortia for efficient wastewater treatment: Optimization using response surface methodology.

The performance of microalgal-bacterial consortia in wastewater treatment and biomass production needs to be further optimized to meet increasingly stringent effluent standards and operating costs. Besides, due to uncontrollability of ambient conditions, it is generally believed that operating conditions (e.g., aeration) respond to ambient conditions (e.g., illumination). Therefore, response surface methodology (RSM) based on Box-Behnken design was used in this study to analyze the removal of chemical oxygen demand (COD), NH3 -N and TP, and algal biomass of the microalgal-bacterial consortia within 48 h. The results showed that under medium illumination intensity (5000 lx), photoperiod (12:12) and aeration rate (0.55 L min -1 ), the removal efficiency of COD, NH3 -N and TP was the highest, and the maximal biomass growth rates were 95.43%, 95.49%, 89.42% and 99.63%, respectively. However, as the limited critical removal requirements of TP, the effluent standards can only be achieved within the small illumination intensity and photoperiod available range, even under medium aeration conditions, which means that under fixed operating conditions, the effective operation range will be very limited. In addition, based on RSM and differential equation analysis, the further study indicated that the effective treatment range can be greatly expanded within aeration responding, which meets the discharge standard of pollutants in China. PRACTITIONER POINTS: Illumination was responded by aeration for optimizing performance of microalgal-bacterial consortium for wastewater treatment and biomass productivity. The strategy of optimization was based on response surface methodology. The maximum effect on wastewater treatment and biomass productivity was based on partial differential equations and quadratic inhomogeneous equations. Limited to critical TP-removal requirements, effluent standards can meet only in the small-usable range of illumination, under medium aeration.

The impact of wastewater treatment effluent on Crocodile River quality in Ehlanzeni District, Mpumalanga Province, South Africa

Excessive discharge of poorly treated effluent has impacted global water resource systems intensely. The declining state of wastewater treatment plants (WWTPs) is a significant source of pollution in water resources. There is evidence of water resource quality deterioration in natural environments caused by effluent discharges. We assessed the impact of wastewater treatment effluent on the quality of the Crocodile River. For spatial distribution, we collected data from three WWTPs discharging effluent into the Crocodile River and from three points situated downstream of each WWTP. Physicochemical and microbiological parameters such as pH, electrical conductivity, chemical oxygen demand, phosphates, nitrates, ammonia, and Escherichia coli were analysed using standard methods of the American Public Health Association. The water quality index was also calculated to give an overall indication of pollution within the catchment. The results show that WWTPs were not complying with the effluent standards set out in their water use licence. The WWTP effluent had a negative impact on downstream water quality, with the water quality index indicating low quality of discharged effluent. It is recommended that a regular and consistent water resource quality monitoring programme be implemented, particularly in areas where effluent discharges are prevalent. Significance: In many African nations, water pollution is a serious problem that may be traced to a variety of sources. Surface water pollution has adverse effects on aquatic ecosystems and reduces the availability of clean water. In most semi-arid to dry southern African regions (e.g. South Africa), water scarcity is a significant concern. In these regions, water is a vital resource that must be protected at all times, given that the inadequate infrastructure of wastewater treatment facilities adds to the decline in South Africa’s water quality standards.

Analysis and Simulation of Waste Water Treatment Plant by Using GPS-X Software

Abstract: Kerala is rich in water resources, which helps to achieve the state to meet most of the water requirements. Due to increased population, most of the water resources are getting depleted. Among the types of water generated according to source , there is a big gap in the treatment of water. The proposed work present is planning to do a review about the modeling of water treatment plants with the help of GPS – X simulation softwares available in the industry . Also it focuses on the role of simulation tools for a better understanding of the treatment process and major trends emerging in the field of water treatment process .water supply and treatment often received more priority than waste water collection and treatment. However, water treatment deserves greater emphasis and should receive greater attention. The purpose of this project is to study the efficiency of the waste water Treatment Plant at karanthoor markaz, calicut This is done by monitoring the main physical, chemical water quality parameters, and comparing them with standards for effluents discharged into surface water. And simulation with the GPS-X software is used and results shows the performance of water treatment plant. In addition, with the software GPS-X, we are trying to improving capacity, operating efficiency and effluent quality by properly optimizing the existing facility can be obtained. This program has a clear-cut graphical interface and uses a specialized translator that converts the graphical process into material balance equations, based on dynamic models. These models allow, besides the kinetic descripton of the treatment process carried out at the water treatment plant, to simulate new scenarios towards the study of critical parameters for the process as well as optimization and control of the water treatment plant. For the modelling of the process it was necessary to collect historical data related to the water treatment plant’s performance over the last 3 years. This data was used as input values for the influent characterisation and as output values to achieve the treated effluent characterisation. Since the first simulation did not lead to the desired output results, it was necessary to proceed to the model calibration, by means of a more detailed study concerning the nutrient and organic fractions of the influent.

Use of aquatic plants in removing pollutants and treating the wastewater: A review

This study illustrates the importance of aquatic plants in removing pollutants and treating wastewater. Aquatic plants provide many benefits to humans, with many new applications still to be identified. However, introducing aquatic plant species that become problematic under specific conditions is putting both marine and freshwater environments at risk right now. These plant species are frequently imported from other regions for medicinal or horticultural purposes, but they eventually escape domestication and establish natural populations. Other pollutants, such as hydrocarbons and other hazardous and carcinogenic substances, can be removed from water using these aquatic plants. The application of growth-promoting bacteria that stimulate the growth of rhizosphere plants and the overgrown plants could be another modification that can have the maximum treating effect. Aquatic plants have many applications in wastewater treatment due to their much lower cost and higher efficiency. Numerous studies have proved Aquatic plants to be sinks for wastewater treatment, and they are also used in the treatment process and to reduce or limit pollutant wastewater. The treated wastewater was of acceptable quality, according to the international effluent standards for irrigation.

Insight into a novel post-anoxic integrated biofilm process for wastewater treatment and reclamation

A novel pilot scale post-anoxic integrated biofilm activated sludge system of capacity 50 m3/d, was used to treat municipal wastewater. Treatment process comprised of three biological reactors which includes aerobic tank with PVA-gel beads followed by anoxic tank and aerobic tank. The plant was operated at HRT of 6 h, with an average SRT of 10 days. Long term performance evaluation of the combined system showed that BOD, COD, TSS and TN removal efficiencies were 91, 90, 93 and 84 % respectively. In PVA-gel tank, significant removal of NH4-N and NO3-N occurred due to nitrification and denitrification process (85 %) in the system. It was observed that the efficiency of SND process varied with temperature and COD/N ratio variation. Maximum TN removal of 80–90 % was noted at temperature range (10–25 °C) and COD/N ratio was 10–22 kg COD/kg of TN. Removal of organic matter and NH4-N in first media tank was dependent on temperature and the loading rates. Significant removal was observed at loading rate 16 kg SCOD/m3 gel/d and 2.4 kg NH4+/m3 gel/d, respectively. The pathogens removal efficacy of the system was higher (>90 %). Bacterial community analysis of immobilized biomass (PVA-gel beads) revealed the presence of Alpha proteobacteria genera, Actinobacterium, Nitrosococcus, Pseudomonas, Fusobacterium and Nitrosomanas species responsible for high carbon and nitrogen removal efficiency of the system. The study concluded that BOD, TSS and TN (<10 mg/L) values were below Indian effluent discharge standards. Average cost to treat 1 m3 of wastewater was calculated as INR 36.05 (electricity input cost: INR 9.6). Overall, post-anoxic integrated biofilm process achieved significant removal of nitrogen and carbon.

Enhancement on the degradation of naproxen in Cu0 activated peroxymonosulfate system by complexing reagents

In recent years, there has been growing interest in the mechanism (radical or nonradical) of persulfate activation processes. In this study, the enhancement of naproxen (NPX) degradation in a Cu0/peroxymonosulfate (PMS) system by complexing reagents was investigated. Surprisingly, neocuproine (NCP) alters the nature of reactive species in the Cu0/PMS system. A high-valent copper species, Cu(III)-NCP, was found to dominate NPX degradation rather than radicals under acid conditions for the first time. Moreover, systematically designed experiments revealed that the Cu(III)-NCP complex was a strong selective oxidant that reacted with organics through a single electron transfer pathway. Meanwhile, the degradation efficiency of NPX was highly dependent on the solution pH and dosage of Cu0 and NCP, but was irrelevant to the concentration of NPX. Additionally, the enhancement of NCP on other copper based PMS activation systems (i.e., Cu2+/HA/PMS and Cu0/HA/PMS systems) was investigated. Considering that the released copper can be removed by a simple precipitation method to meet the effluent standards, the new complex-enhanced Cu0/PMS system provided a new method to enhance the degradation efficiencies of pollutants by a copper-catalyzed Fenton-like system.

Municipal wastewater discharge standards for ammonia nitrogen in Brazil: technical elements to guide decisions.

In Brazil, domestic effluents represent the primary source of pressure on water resources. Water pollution can be controlled by defining, applying, and enforcing the effluent standards for wastewater discharge. Discussions are ongoing in Minas Gerais State regarding the possibility of setting a discharge standard for ammonia nitrogen in municipal wastewater, which is currently not required. However, providing technical support for decision-making is challenging because of the difficulties in accessing monitoring data from sewage treatment plants. This study aimed to analyze the monitoring data from 49 sewage treatment plants operating in Minas Gerais to offer guidance for decision making. High concentrations of ammonia nitrogen in the effluents of the treatment plants were found, reinforcing the need for better control and the adoption of more advanced technologies. Furthermore, it was observed an increase in concentrations downstream of the discharges in the receiving water bodies. Adopting a progressive and adaptable discharge standard can be a solution for better control of treatment systems.

불용성 전극을 이용한 착유세척수 전처리특성 연구

Dairy farmers are required to have a purification facility that meets the legalization of unlicensed livestock and the increasingly stringent effluent water quality standards, with the alternative requirement of consignment treatment application. However, there is no defined standard model that addresses these requirements. Furthermore, even with a purification facility in place, many cases exist in which the purpose of the facility loses its significance because it does not meet the effluent water quality standard. For this reason, the National Institute of Livestock Research published the “Technical Guideline for Purification of Milk Washing Wastewater” in 2016, including data from the Livestock Environment Management Agency which evaluates methods relevant to dairy farmers, including the use of milking washing water purification facilities, livestock manure treatment facilities, and other related technical applications. However, a standard model has not yet been established. In this study, a non-aggregation electrolytic oxidation experiment was performed on raw water used as milking washing water. The results showed that the efficiency of the treatment of total nitrogen and ammonia nitrogen increased proportionally with treatment time, resulting in a removal rate of 81.8% of total nitrogen and 80.7% of ammonia nitrogen. In addition, the results demonstrated that the chromaticity item also increased proportionally to the oxidation time. When considering the water quality measurements of organic substances (BOD₅ and COD_Mn), the treatment efficiency was determined to be limited, with the removal of organic substances limited by the single electrolysis process.

A feasible electro-Fenton treatment of landfill leachate diluted by electro-Fenton effluent: Evaluation of operational parameters, effect of dilution ratio and assessment of treatment cost

In recent years, treatment of landfill leachate is becoming a hot issue in the disposal of municipal solid waste. In this study, electro-Fenton (EF) was conducted to dispose landfill leachate pre-treated by membrane bio-reactor (MBR). The optimum operating parameters were evaluated by the orthogonal experiment: U = 5.5 V, t = 50 min, H2O2/COD0 = 1.5, H2O2/Fe2+ = 2.5 and pH = 4.0. Average COD removal reached 93.90% at a 95% confidence level and voltage, HRT and H2O2/Fe2+ were found to significantly affect COD removal. Landfill leachate was further diluted by distilled water or EF effluent with different dilution ratio and then followed by EF treatment. With a dilution ratio of EF effluent: landfill leachate = 2:1, electro-Fenton got the best treatment performance, whose COD decreased to 36.2 mg/L, meeting the effluent discharge standard of China. The residual active chlorine species and oxidizing matters in EF effluent improved the effect of following electro-Fenton process. Through analysis of ultraviolet-visible spectrometry (UV–vis) and three-dimensional excitation emission matrix fluorescence spectrometry (3D-EEM), humic acids, ultraviolet fulvic acids, visible fulvic acids in landfill leachate was effectively decomposed and the humification of landfill leachate decreased significantly in this treatment mode. Comparing with other reported works, this treatment obtained high removal efficiency (91.90–93.35%), low energy consumption (3.32–6.24 kWh/kgCOD) and low treatment cost (0.853–1.418 US$/m3). This work provided a new perspective in the EF treatment of landfill leachate through diluted by EF effluent with suitable dilution ratio and operating parameters.

Acid Mine Drainage Treatment Using a Process Train with Laterite Mine Waste, Concrete Waste, and Limestone as Treatment Media

Without treatment, the harmful effects of acid mine drainage (AMD) lead to the destruction of surrounding ecosystems, including serious health impacts to affected communities. Active methods, like chemical neutralization, are the most widely used approach to AMD management. However, these techniques require constant inputs of energy, chemicals, and manpower, which become unsustainable in the long-term. One promising and sustainable alternative for AMD management is to use passive treatment systems with locally available and waste-derived alkalinity-generating materials. In this study, the treatment of synthetic AMD with laterite mine waste (LMW), concrete waste, and limestone in a successive process train was elucidated, and the optimal process train configuration was determined. Six full factorial analyses were performed following a constant ratio of 0.75 mL AMD/g media with a 15-min retention time. The evolution of the pH, redox potential (Eh), total dissolved solids (TDS), heavy metals concentration, and sulfates concentrations were monitored as the basis for evaluating the treatment performance of each run. LMW had the highest metal and sulfates removal, while concrete waste caused the largest pH increase. A ranking system was utilized in which each parameter was normalized based on the Philippine effluent standards (DENR Administrative Order (DAO) 2016–08 and 2021–19). Run 4 (Limestone-LMW-Concrete waste) showed the best performance, that is, the pH increased from 1.35 to 8.08 and removed 39% Fe, 94% Ni, 72% Al, and 52% sulfate. With this, the process train is more effective to treat AMD, and the order of the media in treatment is significant.

Perceived drivers and barriers in the governance of wastewater treatment and reuse in India: Insights from a two-round Delphi study

Wastewater treatment and reuse practices are limited in India despite the known benefits of preventing water resources pollution and contributing to sustainable production and consumption systems. We identify the perceived key drivers and barriers to wastewater treatment and reuse governance in a two-round Delphi study, including literature and case study analyses and consultation with 75 panelists. Panelists indicated that the most significant driver for wastewater treatment and water reuse is persistent water scarcity that necessitates diversification to alternative water supplies. In contrast, the most significant barriers are the lack of enforcement of pollution monitoring and control, the lack of an umbrella directive for integrated water resources management, and insufficient collaboration between responsible governmental organizations, central and state water authorities. Given the absence of central guidelines, only a few Indian states such as Maharashtra, Gujarat or Punjab have adopted effective governance structures. These states showcase that defined reuse standards can create successful wastewater treatment and reuse practices but require target-based regulations which are enforced and regularly monitored and financing mechanisms for their long-term operation. The new effluent discharge standards by the National Green Tribunal, the government support programmes, and increasing water scarcity in many parts of India will supposedly drive innovative wastewater treatment and reuse structures. Panelists agreed that efforts are needed to develop technology guiding frameworks following the fit-for-purpose principle and that strengthening institutional and monitoring capacity is crucial to increase confidence in the quality of recovered water resources, create demand, and ultimately safeguard human health and the environment.

Integrating online differential titrimetry and dynamic modelling as innovative energy saving strategy in a large industrial WWTP

Wastewater treatment plants (WWTP) are required to meet increasingly stringent effluent quality standards as well as to improve process sustainability in terms of energy efficiency, in line with the call for a paradigm shift towards the more sustainable concept of wastewater resource recovery facility (WRRF). In this context, optimised Instrumentation, Control and Automation (ICA) systems as well as process and plant-wide modelling have become key tools for optimising economic and environmental costs. The present work reports on the successfull integration of an innovative on-line continuous titrimeter and plant-wide modelling as a support tool for the optimisation of the nitritification unit in a large-scale industrial WWTP. The information gathered from the on-line titrimeter allowed for real-time estimation of the Ammonia Oxidation Rate of the activated sludge and, ultimately, of the nitrification residual capacity of the plant. Results on the titrimeter long-term operation and historical data modelling supported plant managing decisions, such as lowering the dissolved oxygen (DO) set-point of the oxidation unit, straightforwardly resulting in energy saving.Graphical abstract

Investigation of fluoride and silica removal from semiconductor wastewaters with a clean coagulation-ultrafiltration process

Fluoride and silica contamination in water is a worldwide issue due to the wastewater discharge from semiconductor industry. Coagulation-ultrafiltration (UF) process is commonly used to treat semiconductor wastewaters, but it requires excessive amounts of coagulant/flocculant. In this study, a clean coagulation-UF process using chemical mechanical polishing (CMP) wastewater as a coagulant to treat fluoride-containing wastewater was firstly proposed. The fluoride-containing wastewater, CMP wastewater, mixed fluoride-containing wastewater and CMP wastewater, and mixed fluoride-containing wastewater and polyaluminium chloride/polyacrylamide were compared to investigate turbidity removal efficiency, fluoride removal efficiency and membrane fouling resistance. The negatively charged SiO2 particles in CMP wastewater were found to be adsorbed on the positively charged CaF2 particles surface through electrostatic interaction. Results indicated that CMP wastewater provided a superior turbidity removal efficiency and a minimal membrane fouling resistance compared to conventional coagulant. After UF filtration, the fluoride concentration and turbidity were 2.09 mg L−1 and 0 NTU, respectively, which met the median fluoride effluent standard. The extended Derjaguin-Landau-Verwey-Overbeek theory showed that increasing molar ratio of SiO2 to CaF2 improved the interfacial free energy between membrane and suspended particles, thus mitigating membrane fouling. This clean design principle and strategy will broaden the sustainability of coagulation-UF process for wastewater treatment.

공공폐수처리시설의 연계처리 방안에 관한 연구 – 달성1차 산업단지 위주로

In this study, economical and efficient sewage and wastewater treatment methods were analyzed by distributing sewage flowing into the public wastewater treatment facility from the residential area of Dalseong 1st industrial complex to nearby sewage and wastewater treatment facilities. In the future, it was attempted to predict the increase in the amount of wastewater by industry by analyzing the change trend by industry within the Dalseong 1st Industrial Complex. Therefore, the environmental infrastructure around the Dalseong 1st Industrial Complex with the possibility of linked treatment was investigated. Based on this, the Hyeonpung Sewage Treatment Plant was judged to be suitable in consideration of various legal considerations such as the flow rate of each facility and effluent water quality standards. The distance from the public wastewater treatment facility in the Dalseong Industrial Complex to the Hyeonpung sewage treatment plant, the diameter of the pipe, and the type of pipe were reviewed, and the total project cost was more than KRW 2.8 billion. The Dalseong 1st Industrial Complex treats both sewage from residential areas and wastewater from industrial complexes, and the Hyeonpung Sewage Treatment Plant selected as the linked treatment area is a sewage treatment plant. Therefore, it is judged that the administrative procedure for changing the residential area of the Dalseong 1st Industrial Complex from a public wastewater treatment plant to a sewage treatment plant and consultation with related organizations is necessary.

Functionalization of MXene-based nanomaterials for the treatment of micropollutants in aquatic system: A review

The increased industrialization and urbanization generate a larger quantity of effluent that is discharged into the environment regularly. Based on the effluent composition produced from various industries, the number of hazardous substances such as heavy metals, hydrocarbons, volatile organic compounds, organic chemicals, microorganisms introduced into the aquatic systems vary. The conventional wastewater treatment systems do not meet the effluent standards before discharge and require a different treatment system before reuse. Adsorption is an eco-friendly technique that uses selective adsorbents to remove hazardous pollutants even at microscale levels. MXene, a 2-Dimensional nanomaterial with resplendent properties like conductivity, hydrophilicity, stability, and functionalized surface characteristics, is found as a potential candidate for pollutant removal systems. This review discusses the fabrication, characterization, and application of MXene based nanoparticles to remove many pollutants in water treatment systems. The improvement in surface properties and adsorption capacity of MXene based NPs, when modified using different modification agents, has also been discussed. Their feasibility in terms of economic and environmental aspects has been evaluated to understand their scope for practical application in large-scale industries. The challenges towards the synthesis and toxicity's importance have been discussed, with the appropriate recommendations.

Greening Urban Areas with Decentralized Wastewater Treatment and Reuse: A Case Study of Ecoparque in Tijuana, Mexico

In rapidly growing urban areas, such as Tijuana, Mexico, the presence of urban green spaces (UGSs) can help stem soil erosion, improve infiltration, slow runoff, decrease flooding, reduce air pollution, and mitigate climate change. In many water-scarce parts of the world, where centralized wastewater treatment is not accessible or practical, decentralized wastewater treatment systems (DEWATSs) have the potential to supply the water needed for irrigating UGSs. Here, we first review UGS systems supported by DEWATSs and the water quality guidelines and challenges associated with implementing DEWATSs for urban greening in different countries, including Mexico. We also critically examine the linkages between the lack of UGSs in Tijuana, Mexico, extensive soil erosion, and failing sanitation infrastructure that has led to the infamously poor water quality in the Tijuana River. Tijuana’s Ecoparque Wastewater Treatment Facility, a low-energy, aerobic DEWATS, which collects, treats, and discharges residential sewage for localized landscape irrigation, demonstrates how DEWATSs can meet the water demands for urban greening in rapidly urbanizing cities. The aerobic decentralized treatment using a gravity-fed trickling biofilter resulted in a &gt;85% removal of chemical oxygen demand and dissolved organic carbon. Prior to treatment facility upgrades, there was a ~2 log reduction in total coliform and Escherichia coli and a &lt;20% decrease in ammonia from the influent to final effluent. After the addition of a maturation pond in 2020, the effluent met Mexico standards for irrigation reuse, with a ~4 log reduction in fecal coliforms from the influent to final effluent. Case study results demonstrated the potential for decentralized wastewater treatment to meet effluent standards for landscape irrigation, provide water for urban greening, and prevent pollution in the Tijuana River and other urban waterways.

Cost of raising discharge standards: A plant-by-plant assessment from wastewater sector in China

China has implemented increasingly stringent effluent standards for wastewater treatment plants (WWTPs) to protect the aquatic environment, but at the cost of more resource consumption and greenhouse gas emissions. To elaborate tradeoffs between the elevated standard and the additional burden, we compile a 10-year inventory of 6032 WWTPs across China to estimate the impacts of changes in effluent pollutant concentration on operating costs and electricity consumption. Coupled with the increasing demand for wastewater treatment, upgrading standards to the Special Discharge Limit (SDL) by 2030 would increase electricity consumption and operating costs of the wastewater treatment sector by 86.59% and 70.44% compared to the status quo in 2015. The electricity consumption-induced GHG emissions would also increase by 72.21%, which accounts for 29.16% of total emissions in the domestic wastewater treatment sector. Substantial regional differences exist in terms of upgrade-induced resource burden. Less developed regions generally suffer more stress when encountering similar standards elevation. With large-scale microdata, our findings deepen the understanding of the potential cost of raising standards and provide insights into region-customized pollutant effluent standards implementation.

Potential Impacts of Oil and Grease on Algae, Invertebrates and Fish in the Bujagali Hydropower Project Area

This study determined the concentration of oil and grease and inferred its impacts on algae, invertebrates and fish. Water samples were collected in April and September from 2012 to 2018 at the upstream and downstream transects and in the reservoir, and analysed for oil and grease following standard procedures. Environmental compliance was compared to NEMA’s discharge standard of 10 mg/l, and its PAH effluent discharge standard of ≤ 0.1 mg/l. At all sites, average concentrations of oil and grease were below 10 mg/l throughout the sampling period. Out of the 14 data sets for each transect, only 3 along the upstream transect, and 2 at each of the downstream transect and the reservoir were compliant with the effluent discharge standard. Although impacts of oil and grease on aquatic biota were not assessed, their relatively high concentration compared to total Polycyclic Aromatic Hydrocarbon (&gt; 0.1 µg/l) is considered hazardous to most aquatic organisms. The diverse activities around the project area implied that sources of oil and grease were proportionately diverse. Hence, the observed trends may not solely be attributed to the hydropower project. Accordingly, assessment of the various sources of oil and grease and their impact on aquatic biota in the area is recommended.