Discharge Standards Research Articles

Comparison of Soil Nitrate and Phosphorus Concentrations Prior to and Five to Eleven Years after Recycled Water Irrigation

Increasing demand on water supplies in western US and more stringent wastewater discharge standards have made recycled water a common water source for irrigating urban green spaces. Studies are needed to evaluate nitrate-N leaching potential and phosphorus (P) movement along soil profile when recycled wastewater is used for irrigation. We collected and analyzed soil samples at the commencement and 5 and 11 years after recycled water irrigation on 2 golf courses, 5 metropolitan parks, and 1 school ground. Samples were taken at 0-20, 20-40, 40-60, 60-80, and 80-100 cm depths on golf courses and at 0-20 and 20-40 cm depths at other locations. Soil samples were tested for soil pH, soil nitrate, and AB-DTPA extracted P level. No increase in soil nitrate-N was observed over 5 and 11 years with recycled water irrigation, suggesting leaching of nitrogen to the groundwater was not a great concern. Soil P concentration at the surface soil depth was the highest 11 years after recycled water irrigation. Moreover, soil P increasing below the surface layer was observed on sites with sandy soil, suggesting long-term recycled water irrigation could impose some risk for P leaching on sandy soil.

Treatment of catalyst wastewater through an environmentally friendly electrodeposition-precipitation-electrooxidation coupling process: Recovery of copper and silicate, and removal of COD

An environmentally friendly coupling process of electrodeposition—chemical precipitation—electrooxidation was explored to recover copper and silicate, and remove COD, showing a promising effect in treating catalyst wastewater. The feasibility and the key influencing factors of the process were investigated. The results showed that more than 99.8% of copper and 89.7% of silicate were recovered through the electrodeposition process and precipitation process, and 96.4% of COD was removed in the electrooxidation process. The purification of recovered copper was higher than 99.12% and the residual COD was lower than 500 mg/L. A higher initial pH value (>12.9) or the addition of a certain amount of NaCl is essential in avoiding the fouling of the anode in the electrodeposition process. In the chemical precipitation process, CaCl2 was selected as the precipitator, and the dosage of Ca: Si molar ratios of 1:1 was feasible for silicate removal. After processing, the content of copper and COD met the discharge standard.

Understanding advances and challenges of urban water security and sustainability in China based on water footprint dynamics

Sustainability of China’s numerous cities are threatened by both quantity- and quality-induced water scarcity, which can be measured by the water footprint from a consumption (WFcons) or production (WFprod) perspective. Although WFcons was widely assessed, the changes in WFprod of China’s cities were still unclear. A large-scale decrease in urban WFprod in China was found, with the average WFprod decreasing from 13.8 billion m3 to 10.3 billion m3 and the per capita WFprod decreasing from 1614.8 m3/person to 1184.0 m3/person (i.e., falling by more than a quarter in just six years). Such shrinkage was particularly evident in drylands, eliminating the water deficit in Xi’an and Xining. The reduction in grey WFprod caused by implementing water pollution prevention policies and other relevant measures played the most important role in the savings. In the future, the implementation of updated pollution discharge standards is projected to allow more cities to escape water deficits; however, the rapid growth of the domestic and ecological blue WFprod caused by urbanization and urban greening would destabilize this prospect. Thus, attention should be given to both water pollution prevention and domestic and ecological blue WFprod restriction to further alleviate urban water scarcity in China.

Molecular insights into the dissolved organic matter of leather wastewater in leather industrial park wastewater treatment plant

Leather wastewater (LW) effluent is characterized by complex organic matter, high salinity, and poor biodegradability. To meet the discharge standards, LW effluent is often mixed with municipal wastewater (MW) before being treated at a leather industrial park wastewater treatment plant (LIPWWTP). However, whether this method efficiently removes the dissolved organic matter (DOM) from LW effluent (LWDOM) remains debatable. In this study, the transformation of DOM during full-scale treatment was revealed using spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry. LWDOM exhibited higher aromaticity and lower molecular weight than DOM in MW (MWDOM). The DOM properties in mixed wastewater (MixW) were similar to those in LWDOM and MWDOM. The MixW was treated using a flocculation/primary sedimentation tank (FL1/PST), anoxic/oxic (A/O) process, secondary sedimentation tank (SST), flocculation/sedimentation tank, denitrification filter (FL2/ST-DNF), and an ozonation contact reactor (O3). The FL1/PST unit preferentially removed the peptide-like compounds. The A/O-SST units had the highest removal efficiencies for dissolved organic carbon (DOC) (61.34 %) and soluble chemical oxygen demand (SCOD) (52.2 %). The FL2/ST-DNF treatment removed the lignin-like compounds. The final treatment showed poor DOM mineralization efficiency. The correlation between water quality indices, spectral indices, and molecular-level parameters indicated that lignin-like compounds were strongly correlated with spectral indices and CHOS compounds considerably contributed to the SCOD and DOC. Although the effluent SCOD met the discharge standard, some refractory DOM from LW remained in the effluent. This study illustrates the composition and transformation of DOM and provides theoretical guidance for improving the current treatment processes.

Sequential treatment of landfill leachate by electrocoagulation/aeration, PMS/ZVI/UV and electro-Fenton: Performance, biodegradability and toxicity studies

This study presents a systematic study on sequential treatment of highly resistant landfill leachate by electrocoagulation (EC)/aeration, sulfate radical advanced oxidation process (SR-AOP) and electro-Fenton (EF). In case of SR-AOP, peroxymonosulfate (PMS) catalyzed by zero valent iron (ZVI) and ultraviolet irradiation (UV) system was developed. Treatment process was optimized in respect to COD removal. Analysis of results revealed that sequential application of EC/aeration, PMS/ZVI/UV, and EF processes provide an extraordinary performance and meet the environmental regulations. The source of iron for EF process was provided from previous process reducing the cost of sequential process. Separately, EC/aeration (inlet COD = 4040 mg/L), PMS/ZVI/UV (inlet COD = 1560 mg/L), and EF (inlet COD = 471 mg/L) removed 61, 69 and 82% of COD respectively. Overall, sequential processes of EC/aeration, PMS/ZVI/UV and EF could remove the COD, TOC and ammonia of the landfill leachate around 98%, 93% and 94%, respectively. The comparison of different sequences of following processes indicated that current configuration (EC/aeration-PMS/ZVI/UV-EF) could meet the discharge standards. Furthermore, humification degree was significantly improved after oxidative processes. Biodegradability study was also performed by means of BOD/COD, average oxidation state (AOS), and Zahn-Wellens test, and the best results associated with these indices were obtained 0.56, 2.37, and over 98%, respectively. Phytotoxicity of leachate was remarkably reduced and the final effluent can be considered as a non-phytotoxic wastewater.

Municipal Wastewater Treatment in Iran: Current Situation, Barriers and Future Policies

With population and economy growth, water usage, wastewater generation and treatment, treatment plants capacity and innovation ability in Iran have increased dramatically in the last decades. Currently, Iran is in the grip of severe water scarcity, with renewable water availability of less than 1700 m3 /capita/y. Total municipal wastewater generated in Iran is 4.61 billion m3 /y out of which only 42% is treated. The conventional activated sludge process accounted for the largest share (>60%) in municipal wastewater treatment in Iran. The treatment plants operational costs usually amount up to 0.2 US $/m3 wastewater. About 55% of treated municipal effluent is reused in Iran, with an emphasis on the agricultural sector. The electricity consumption in municipal wastewater treatment facilities amounts for 0.1% (241 million kWh/y) of the total electricity consumption of the country. Meanwhile, the current laws and policies are sometimes inefficient or do not prompt the ideal outcomes. Thus, the present study provides an overview of municipal wastewater treatment in Iran by describing the current situation and collecting data from 68 treatment plants, and defining key barriers and future policies needs towards Iran’s sustainable municipal wastewater management (up to 2040). Here, the opinions of 50 experts from the governmental sector, industry division, and faculty members were surveyed through the meetings of the technical and steering committee. Overall, sustainable municipal wastewater management in Iran would be obtained by developing water resources, increasing the population covered by wastewater facilities (90%), improving effluent discharge standards, and lowering energy usage to 0.45 kWh/m3 wastewater.

Performance and microbial analysis of a fluidized bed membrane bioreactor operated in the partial nitrification and anammox (PN/A) mode for polishing anaerobically treated effluent to industrial discharge standard

This study evaluates the performance and microbial dynamics of an ORP-controlled fluidized bed membrane bioreactor impregnated with partial nitrification and anammox culture (FMBRPN/A) for polishing the low COD/NH4+ anaerobically treated effluent of the seafood processing industry. Results showed that the highest average removal of COD and total nitrogen were 68.6% and 75.0% at COD/NH4+ 0.44 and 0.33, respectively. Heterotrophic denitrification accounted for only 3.0–7.1% of the overall nitrogen removals at COD/NH4+ 0.33–0.55. A low nitrite oxidation rate observed indicated that almost all NO3- came from anammox reactions. Data on ammonia oxidation rate, nitrite oxidation rate, and anammox nitrogen removal rate pointed to the competitive advantage between heterotrophic and nitrifying/anammox consortia at higher and lower COD/NH4+ ratios. When salinity threat at 5 g/L NaCl in the influent was imposed to FMBRPN/A, nitrogen removal was almost completely eliminated but quickly recovered to 25.5% as organic removal was not affected. Activities of the nitrogenous autotrophic organisms and heterotrophic microbes were strongly dependent on the presence of organic and salinity in the wastewater. Microbial analysis of biofilm formed on the membrane surface showed a significant difference in the succession of dominant bacteria during the experiments. Next Generation Sequencing indicated the dynamic shifting proportions of ammonium oxidizing bacteria (AOB), nitrite oxidization bacteria (NOB), denitrifying bacteria (DNB), and anammox bacteria (AMX) ranging from 49.4% to 64.2% at various COD/NH4+ ratios, which suggested their syntrophic relationship. Superior membrane retention of FMBRPN/A for heterotrophic and slow-growing autotrophic cells facilitated system stability and efficiency to meet the industrial effluent standard.

Oxidation treatment of shale gas produced water: Molecular changes in dissolved organic matter composition and toxicity evaluation

Produced water (PW) is the largest waste stream generated by hydraulic fracturing in an unconventional shale gas reservoir. Oxidation processes (OPs) are frequently used as advanced treatment method in highly complicated water matrix treatments. However, the degradation efficiency is the main focus of research, organic compounds and their toxicity have not been properly explored. Here, we obtained the characterization and transformation of dissolved organic matters of PW samples from the first shale gas field of China by two selected OPs using FT-ICR MS. CHO, CHON, CHOS, and CHONS heterocyclic compounds associated with lignins/CRAM-like, aliphatic/proteins, and carbohydrates compounds were the major organic compounds identified. Electrochemical Fe2+/HClO oxidation preferentially removed aromatic structures, unsaturated hydrocarbons, and tannin compounds with a double-bond equivalence (DBE) value below 7 to more saturated compounds. Nevertheless, Fe (VI) degradation manifested in CHOS compounds with low DBE values, especially single bond compounds. Oxygen- and Sulfur-containing substances, primarily O4–11, S1O3-S1O12, N1S1O4, and N2S1O10 classes, were the main recalcitrant components in OPs. The toxicity assessment showed that the free-radical-formed Fe2+/HClO oxidation could cause significant DNA damage. Therefore, the toxicity response byproducts need spcial attention when conducting OPs. Our results led to discussions on designing appropriate treatment strategies and the development of PW discharge or reuse standards.

Stimulating carbon and nitrogen metabolism of Chlorella pyrenoidosa to treat aquaculture wastewater and produce high-quality protein in plate photobioreactors

Wastewater treatment by microalgae is the economical and environmentally friendly strategy, but is still challenged with the strict discharge standards and valuable biomass exploitations. The carbon and nitrogen metabolism of Chlorella pyrenoidosa was improved by the red LED light and starch addition to treat Tilapia aquaculture wastewater (T-AW) and produce protein simultaneously in a plate photobioreactor. The red LED light was applied to improve the nutrient removals at an outdoor temperature, but the concentrations except total nitrogen did not satisfy the discharge standards. After starch addition, the removal efficiencies of total phosphorus, total nitrogen, chemical oxygen demand, and total ammonia nitrogen were 85.15, 96.96, 88.53, and 98.01 % in a flat-plate photobioreactor, respectively, which met the discharge standards and the protein production reached 0.60 g/L. At a molecular level, the metabolic flux and transcriptome analyses showed that red light promoted carbon flux of the Embden-Meyerhof-Pranas pathway and tricarboxylic cycle, and upregulated the levels of genes encoding α-amylase, glutamine synthetase, glutamate dehydrogenase, nitrate transporter, and ammonium transporter, which facilitated nutrients removal and provided nitrogen sources for protein biosynthesis. The harvesting C. pyrenoidosa possessed the 62 % essential amino acids and great lipid composition for biofuels. This study provided a new orientation for outdoor wastewater treatment and protein production by collaboratively regulating the carbon and nitrogen metabolism of microalgae.

Pilot experimental study on pollutant emission characteristics from co-combustion of coal and spent cathode carbon block

Spent cathode carbon block (SCCB) is a hazardous waste produced by the electrolytic aluminum industry. Collaborative treatment of the SCCB in pulverized coal boilers is a potentially valuable technology. Pilot experiments were carried out on a 240 t/h pulverized coal boiler and its supporting flue gas treatment measures as a function of the mixing ratio of SCCB to verify the feasibility of coal collaborative disposal of SCCB. The thermal conversion characteristics of fluoride after mixing SCCB with coal were studied. A continuous emission monitoring system was used to monitor the impact on SO2, NOx and particulate matter in real time. The effectiveness of existing flue gas control measures was evaluated, and optimization suggestions of the flue gas control measures were postulated. The content of heavy metals (Hg, Cd, Ni, Pb, As, Se) in solid waste from co-combustion and the physical phase of solid waste were investigated. In addition, the transformation of heavy metals such as Hg, Cd, Ni, Pb, Cr, As and fluoride in defluorination wastewater during flue gas treatment were analyzed. The results show that it is feasible to use a pulverized coal boiler to dispose SCCB. The existing flue gas treatment measures proved to be appropriate, and desulfurization wastewater can achieve the discharge standards. Defluorination gypsum, fly ash and slag are not hazardous waste. When the mixing ratio of SCCB is increased, the existing neutralization and flocculation precipitation processes of the desulfurization wastewater are affected. It is suggested to add Al2O3 for the defluorination process before the desulfurization tower.

Fate of Naturally Dissolved Organic Matter and Synthetic Organic Compounds Subjected to Drinking Water Treatment Using Membrane, Activated Carbon, and UV/H2O2 Technologies.

Organic pollutants are toxic and are present in drinking water. The conventional processes of most water plants can basically meet the discharge standard. However, based on the improvement of the objective of organic pollutants control and the constant change of water characteristics, the results may not be ideal. This study evaluates the effectiveness of different treatments such as microfiltration, nanofiltration, reverse osmosis, activated carbon, and ultraviolet irradiation/H2O2 in terms of the removal of organic pollutants. Among the DOM results, nanofiltration, reverse osmosis, and activated carbon showed optimal performance due to the characteristics of processes and the compound properties. However, the risks of low-molecular-weight organic residue and byproduct formation are still present. Thirty-nine species of synthetic organic compounds (SOC) were qualitatively and semiquantitatively analyzed. Different technologies showed varying removal capabilities for SOC based on their properties and many substances coexisted leading to abnormal removal performances. These residual organics showed the characteristics of lower molecular weight, more hydrophilicity, further unknown impacts, and with risk of DBPs. Based on the above insights, possible methods can be rationally chosen for on-demand decontamination of organics in unconfined aquatic environment and long-time impact on water characteristics and human health also should be considered.

Reductive roasting of arsenic-contaminated red mud for Fe resources recovery driven by johnbaumite-based arsenic thermostabilization strategy

Arsenic-contaminated red mud (As-RM) is a hazardous waste with limited recycling approaches. Generally, through reductive roasting and magnetic separation, RM could be transformed into Fe-rich concentrate for Fe resource recovery. However, due to the poor thermostabilization of As species, reductive roasting of As-RM would cause severe As volatilization pollution together with high As leaching risks from heated residue. Herein, a novel johnbaumite-based As thermostabilization strategy is developed for clean Fe resources recycling from As-RM. We found that in the presence of Ca(OH)2, the As species in As-RM could be immobilized as thermostable and insoluble johnbaumite (Ca5(AsO4)3OH) at 900 °C, effectively enhancing the As thermostability and insolubility. Introducing 1.5% Ca(OH)2 into As-RM suppressed the As volatilization ratio from 60.3% to 15.7% during reductive roasting. Meanwhile, the As leaching concentration of the reduced residue was reduced to < 100 µg/L, thus satisfying the Japanese wastewater discharge standard. A concentrate with approximately 67.5% total iron grade was obtained from As-RM through this clean reductive roasting and magnetic separation. Overall, the approach introduced in this work effectively reduces the As diffusion pollution deriving from As-RM thermal reduction, which could contribute to hazardous As-RM reutilization, clean Fe resources recovery, and As pollution mitigation.

Separation of butyl acetate and propyl acetate from wastewater by liquid-liquid extraction and molecular dynamics simulation

Pharmaceutical production processes produce ester-containing wastewater, and the concentration of esters must be reduced to a specific limit for wastewater discharge. Therefore, this study investigated a synthetic menthol eutectic solvent to separate the ester-water mixture and meet industrial discharge standards. A deep eutectic solvent (DES) composed of menthol as the hydrogen bond acceptor and lauric acid as the hydrogen bond donor in a molar ratio of 2:1 was synthesized to study the liquid–liquid extraction experiment by separating mixtures of water and propyl acetate (PA) and water and butyl acetate (BA) at 1 atm. In addition, a temperature range of 273.15–318.15 K was used to measure the influence of temperature on the experimental results within a 5 K interval. The experimental results indicated that the increase in temperature promoted the extraction efficiency of ester to some extent, but the fluctuation range was unclear. The DES had a high distribution coefficient (β) and selectivity (S) for ester, enabling a better separation of ester and water. Thereafter, molecular dynamics (MD) simulations were performed to ascertain the mechanism of the DES extraction of esters, and the molecular simulations were used to calculate the interaction energy, radial distribution function (RDF), spatial distribution function (SDF), and self-diffusion coefficient (D). The results of the MD simulations illustrated that menthol played an important role in the extraction process, and the hydrogen bond force between menthol and ester was the main force in the extraction process. Both BA and PA were effectively removed from the water by the DES. In general, the excellent extraction ability of the DES for esters was verified by experiments and simulation, which provides solid theoretical support for ester separations in other fields.

Impact of the Controlled Dump of Fez City (Morocco): Evaluation of Metallic Trace Elements Contamination in the Sediments

In order to qualify and quantify the impact of sediment contamination in hydric settings by metallic trace elements (MTE) emanating from the controlled dump of Fez city (northern Morocco), leachate and sediment sample analyses were carried out. The leachates collected from the 24 sites are characterised by a pH between 6.91 and 8, a COD varying between 430.7 and 7962 mg/L, an NTK content up to 1955 mg/L, with an average of 1514 mg/L, and a nitrate concentration reaching 46 mg/L in some samples, which exceeds the standards for discharges into the natural environment. The chromium content emanating mainly from household waste varies between 1.69 and 4.90 mg/L. The MTE content (As, Cd, Co, Cr, Cu, Ni, Pb, Zn and Fe) of the different leachates varies from one basin to another. The sediments downstream of the dump along the sampling profile show pH values between 7.34 and 8.21 (compared to 7.96–8.82 for the reference samples), and electrical conductivity values fluctuate between 1.21 ms/cm and 5.37 ms/cm for the contaminated sediments (compared to 0.8 ms/cm for the reference sediment). The analysis of metallic trace elements in the sediments by ICP-AES shows that their content varies slightly from one sampling point to another. Furthermore, they do not vary considerably from the surface (0 cm) to the depth (20 cm). The average values of metallic element concentrations are 45.83 ± 2.14 mg/Kg for Cu, 4.40 ± 0.07 mg/Kg for Cd, 43.76 ± 3.40 mg/Kg for Cr, 72.99 ± 1.85 mg/Kg for Ni, 21.71 ± 6.55 mg/Kg for Pb and 102.02 ± 7.28 mg/kg for Zn. In effect, the negative environmental impact of Fez controlled dumping site is ostensibly underlined both by (i) the pollution load index values, which indicate a strong and progressive deterioration along the thalweg, and (ii) the statistical analysis (PCA), which reveals a common origin of the deduced pollutants through the strong correlation between the majority of the analysed elements.

Treatment Technology and Research Progress of Residual Xanthate in Mineral Processing Wastewater

Xanthate is the most widely used and effective collector in the flotation of sulfide minerals. However, the residual xanthate in flotation wastewater may cause serious environmental pollution and even human health hazards. At present, a variety of treatment technologies have been developed to degrade xanthate pollutants in wastewater, with the aim of meeting safe discharge standards. This work reviews the research status of xanthate wastewater treatment technologies in recent years. Treatment technologies are evaluated, including coagulation flocculation, adsorption, microbiological, Fenton, ozone oxidation, and photocatalytic methods. The reaction mechanisms and advantages, as well as disadvantages, of the various treatment technologies are summarized. Future research on the treatment of xanthate wastewater should focus on combined methods, which will be conducive to achieving a high efficiency and low cost, with no secondary pollution, and with the aim of generating further original and innovative technologies.

A green hydrothermal synthesis of polyacrylonitrile@carbon/MIL-101(Fe) composite nanofiber membrane for efficient selective removal of tetracycline

Developing highly efficient, low-cost and reusable adsorbents toward antibiotics is a great challenge for the treatment of wastewater. Here, a polyacrylonitrile@carbon/MIL-101(Fe) composite nanofiber membrane (PAN@C/MIL-101(Fe)) has been prepared for the first time via the combination of electrospinning technique and green hydrothermal method and showed a high adsorption performance toward tetracycline (TC). The MIL-101(Fe) nanocrystals were uniformly grown in-situ on the surface of activated hydrothermal carbon coated electrospun PAN nanofiber membrane. The incorporation of hydrothermal carbon and MIL-101(Fe) in nanofiber membrane obviously enhanced its adsorption ability. The adsorption process followed pseudo-second-order kinetic model and Freundlich isotherm model, with an adsorption capacity of 392.64 mg/g for TC. Moreover, the PAN@C/MIL-101(Fe) exhibited high selectivity and good regenerability, and the removal efficiency remained above 94% after five cycles. After the real wastewater filtration experiment, chemical oxygen demand (COD) concentration of TC significantly decreased from 155.55 mg/L to 51.84 mg/L, which is below the standard of wastewater discharge (GB 21904-2008). This study provides a promising green strategy for uniform MOFs modified carbon coating nanofiber membrane adsorbent, which has potential application in practical antibiotic wastewater treatment.

An online intelligent management method for wastewater treatment supported by coupling data-driven and mechanism models

The management of traditional wastewater treatment plants(WWTPs) mostly rely on human experience, resulting in high cost and low efficiency under conservative operation mode. This study proposed an online intelligent management method based on plan library to improve the wastewater treatment performance. The operation plans in plan library were obtained based on the mechanism model (Activated Sludge Models) of a pilot Anaerobic-Anoxic-Oxic (A2/O) process, and each plan represents the optimal operation strategy under a specific influent condition. Then the plan library was input to train a data driven model, i.e. a Multi-Layer Perceptron (MLP) regression model. The trained MLP model can be used to generate more detailed online operation strategies for wastewater treatment process under different influent conditions. After a 124 days continuous operation of the A2/O process, the results shown, the proposed method can generate online operation strategies according to influent conditions, and the main effluent indicators meet the discharge standards continuously and stably. Meanwhile, compared with the manual operation mode, the aeration energy consumption was saved about 49.4 % by using the proposed method. The mechanism model and data-driven model were combined in this study, and it has scientific value and engineering significance for intelligent management of WWTPs.

Assessing groundwater recharge rates, water quality changes, and agricultural impacts of large-scale water recycling

The over-exploitation and insufficient replenishment of groundwater (GW) have resulted in a pressing need to conserve freshwater and reuse of treated wastewater. To address this issue, the Government of Karnataka launched a large-scale recycling (440 million liters/day) scheme to indirectly recharge GW using secondary treated municipal wastewater (STW) in drought-prone areas of Kolar district in southern India. This recycling employs soil aquifer treatment (SAT) technology, which involves filling surface run-off tanks with STW that intentionally infiltrate and recharge aquifers. This study quantifies the impact of STW recycling on GW recharge rates, levels, and quality in the crystalline aquifers of peninsular India. The study area is characterized by hard rock aquifers with fractured gneiss, granites, schists, and highly fractured weathered rocks. The agricultural impacts of the improved GW table are also quantified by comparing areas receiving STW to those not receiving it, and changes before and after STW recycling were measured. The AMBHAS_1D model was used to estimate the recharge rates and showed a tenfold increase in daily recharge rates, resulting in a significant increase in the GW levels. The results indicate that the surface water in the rejuvenated tanks meets the country's stringent water discharge standards for STW. The GW levels of the studied boreholes increased by 58–73 %, and the GW quality improved significantly, turning hard water into soft water. Land use land cover studies confirmed an increase in the number of water bodies, trees, and cultivated land. The availability of GW significantly improved agricultural productivity (11–42 %), milk productivity (33 %), and fish productivity (341 %). The study's outcomes are expected to serve as a role model for the rest of Indian metro cities and demonstrate the potential of reusing STW to achieve a circular economy and a water-resilient system.

Assessing the Effect of a Newly Implemented Basic Wastewater Discharge Standard on the Concentrations of Pharmaceutical and Personal Care Products in the Daqing River Basin, China

Wastewater discharge standards often play a crucial role in water environmental management. However, most of these standards only focus on conventional water pollutants such as chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD5), ammonia (NH3-N), total nitrogen (TN), and total phosphorus (TP). It is unclear if there is an impact on the removal of pharmaceuticals and personal care products (PPCPs). The Daqing River Basin is an important water system in China. In 2018, a new wastewater discharge standard for the Daqing River Basin (DB 13/2795–2018) was issued, which mainly limits the discharge of conventional water pollutants, including COD (20–40 mg L−1), BOD5 (4–10 mg L−1), NH3-N (1–2 mg L−1), TN (10–15 mg L−1), and TP (0.2–0.4 mg L−1). Herein, we evaluated the performance of the new wastewater discharge standard, especially the effect on the removal of PPCPs. We characterized the occurrence of PPCPs and the resulting ecological impact in the basin, and compared the occurrence of PPCPs before (2017) and after (2021) implementation of the standard. A total of 16 PPCPs were detected, of which diclofenac, carbamazepine, ibuprofen, and bezafibrate pose risks to crustaceans and fish in the basin. A positive impact from the implemented standard, on the removal of some PPCPs, was confirmed, especially for lincomycin and trimethoprim.

Стабильность выбросов радионуклидов при нормальной эксплуатации АЭС

The issue of stability of radionuclide discharges of nuclear power plants under normal operation is discussed in the article. A hypothesis about the stability of the characteristics of atmospheric emissions from nuclear power plants and the stability of the total dose created by the activity of the emissions under consideration has been proposed and tested. It is shown that the average characteristics of the discharges of nuclear power plants under normal operation are stable and can be used to establish discharge standards.