ObjectiveDriven by the digital transformation wave, municipal wastewater treatment plants (WWTPs) are evolving from traditional “treatment” mode toward intelligent “smart management” mode. In China, activated sludge is commonly used in urban WWTP, highlighting an urgent need for digital modeling tools to achieve refined process control. BioWin, a simulation platform developed on ASM foundations, offers functionalities such as process design optimization, effluent quality prediction, and energy-saving analysis, demonstrating substantial potential for broader adoption. However, systematic studies on its practical applications remain limited.MethodsThis study presents a structured review of BioWin-related research over the past decade, encompassing both domestic and international literature. The general modeling workflow is delineated, and applications are categorized across key areas: engineering design, process diagnosis, operational optimization, and pollutant reduction simulation. Typical case examples are examined to illustrate application characteristics and identify method ological trends.ResultsBioWin delivers reliable and adaptable performance for precise simulation and process control, effectively supporting multi-dimensional technical management in WWTP. Its capabilities facilitate scenario analysis for design modifications, assessment of operational strategies, and evaluation of energy and resource savings. However, there are certain technical bottlenecks in model localization, input parameter acquisition, and long-term operation (such as influent characteristics and kinetic coefficients), as well as ensuring the long-term stability of the model under different operating mechanisms.ConclusionAs a key tool for promoting the intelligent management of WWTP, BioWin exhibits clear technical advantages and promising applicability. Future research should focus on model localization adaptation, deep integration with real-time monitoring systems, and improvement of user-friendliness to achieve dynamic model updating and online decision support; enhance the user interface and automation functions to improve the availability of operation personnel and engineers in WWTPs. Addressing these aspects will further broaden BioWin's application depth and scope in WWTP contexts, thereby advancing the digital and intelligent transformation of the sector.

ObjectiveNitrous oxide (N2O), a potent greenhouse gas, contributes over 80% of the carbon footprint in wastewater treatment systems. Accurately analyzing its generation mechanism is critical for optimizing treatment processes and reducing carbon emissions.MethodsUsing microelectrode technology, this paper systematically reviewes the in situ monitoring of N2O within sludge aggregates and quantifies the regulation of N2O generation by dissolved oxygen gradients through a coupled diffusion-reaction model. The study encompasses traditional nitrification-denitrification processes and novel short-cut nitrogen removal systems (e.g., anaerobic ammonium oxidation).ResultsIn traditional nitrification-denitrification systems, N2O release exhibite significant spatial heterogeneity within sludge aggregates. The N2O emission factor in aerobic zone reaches 2.1%, of which 53.6% is contributed by aeration stripping. During denitrification, low carbon/nitrogen ratios (C/N<3) and low pH value (<6.5) increases N2O yields to 2.7 times and 65.0% of baseline values, respectively, due to electron donor competition and nitrous oxide reductase (NOS) inhibition. In anaerobic ammonium oxidation granules, N2O production hotspots (600~1 300 m) showes limited correlation with anaerobic ammonium oxidation bacterial activity, while ammonia-oxidizing bacteria denitrification contributes 68% ± 5% of total N2O. Optimizing oxygen mass transfer via the diffusion-reaction model [e.g., membrane aeration biofilm reactor (MABR)] reduces the N2O emission factor to 0.005 8%.ConclusionMicroelectrode technology elucidates microscale N2O generation mechanisms. Future efforts should focus on developing multi-parameter microelectrode arrays integrated with microbiomics and computational fluid dynamics (CFD) simulations to enable cross-scale analysis of "mass transfer-reaction-microbial community" interactions, advancing decarbonized and precision-controlled wastewater treatment.

ObjectiveAs the world's largest producer and consumer of chemical nickel plating, China generates a massive annual volume of chemical nickel plating wastewater. The toxicity of nickel poses significant threats to ecological environments and human health. However, as an important resource, nickel is widely used in various fields such as alloys, batteries, electronics, chemicals, military, and aerospace, and the demand for nickel is expected to grow continuously in the future. In the context of the “dual carbon” goal, the treatment and disposal of chemical nickel wastewater needs to be considered from the perspective of total process pollution prevention and control, taking into account nickel pollution prevention, pollutant removal and resource recovery.MethodsThis paper summarizes the sources and characteristics of chemical nickel plating wastewater, analyzes the improvement directions of clean production in chemical nickel plating enterprises. In the chemical nickel wastewater treatment, this paper systematically analyzes the mechanism and application of traditional technology, new technology and combined technology, and summarizes the advantages and disadvantages of these technologies in application. In the resource recovery of chemical nickel wastewater, this paper systematically analyzes and introduces the recovery technology mechanism and application of phosphorus resources, nickel resources and water resources, and classifies and explains the recovery technology of wastewater with different nickel concentrations.ResultsThe improvement paths for clean production of chemical nickel plating in enterprises are clarified, including improving the utilization rate of nickel, reducing nickel emissions, and applying intelligent technologies. The advantages and disadvantages of various technologies in the treatment of chemical nickel plating wastewater are summarized, and it is found that new and combined technologies can significantly improve treatment efficiency and effectiveness. Different resource recovery technologies for wastewater with different nickel concentrations are sorted out, providing references for engineering applications.ConclusionThrough multi-faceted research on the treatment and resource recovery of chemical nickel plating wastewater, this paper provides references and guidance for the treatment and resource recovery of chemical nickel plating wastewater under the "dual carbon" goals, and looks forward to the future development of chemical nickel plating wastewater treatment, promoting the further optimization and application of related technologies.

ObjectiveAs a pretreatment unit in seawater desalination, ultrafiltration (UF) serves as a critical barrier to ensure the stable operation of the core desalination reverse osmosis membrane. However, under low winter temperatures in northern China, traditional organic UF membranes face significant challenges, including reduced water production capacity and increased membrane filament breakage rates. To address these issues, this study conductes pilot-scale demonstrations of low-temperature seawater desalination pretreatment using domestically developed inorganic ceramic UF membranes, which exhibit high mechanical strength and thermal stability.MethoodsUnder both ambient (from 16.7 to 20.9 ℃) and low-temperature (from 2.2 ℃ to 5.0 ℃) conditions, constant-pressure and constant-flow operational modes were employed to evaluate and compare the permeate flux, transmembrane pressure difference (TMP), and water production variations of ceramic and organic membranes.ResultsUnder constant-pressure operation, ceramic membranes demonstrated significantly higher permeate flux than organic membranes at ambient temperatures. Although the permeate flux of ceramic membranes declined more markedly than that of organic membranes under low-temperature conditions, they still outperformed organic membranes. Under constant-flow operational mode, ceramic membranes could enhance filtration driving force by increasing the TMP, thereby maintaining stable water production. In contrast, low-temperature conditions exerted a more pronounced adverse effect on organic membranes, with their water yield dropping to merely from 37% to 41% of that observed under ambient temperatures.ConclusionThe domestically developed ceramic membranes exhibit superior water production stability compared to organic membranes in low-temperature pilot-scale trials. These findings provide technical references and operational parameter guidelines for the practical application of ceramic membranes in low-temperature seawater desalination pretreatment processes.

ObjectiveThe production tailwater from water treatment plants (WTPs) primarily includes sludge discharge water from sedimentation tanks and backwash water from filters, accounting from 6% to 10% of the water production capacity of the WTP. By analyzing the water quality characteristics of production tailwater and investigating its direct reuse technologies, this study can provide technical references for the recycling of WTP tailwater, which holds significant practical importance for advancing the construction of a water-saving society.MethodsIn the paper, a pilot-scale plant for the reuse of supernatant from a concentration tank was used to systematically study the water quality characteristics of the supernatant from the concentration tank and the impact of direct reuse of supernatant from the concentration tank (reuse ratio of 3∶1) on the water quality of raw water, sand filter outflow, sedimentation tank sludge discharge, and filter backwash water.ResultsThe turbidity of the supernatant in the concentration tank was less than 6 NTU, significantly lower than the turbidity of the raw water. The ammonia content was from 0.04 mg/L to 0.12 mg/L, almost equivalent to the ammonia content in the raw water. The permanganate index was equivalent to the raw water, and it was lower than 4 mg/L. The total bacterial count fluctuated between 500 CFU/mL and 1 000 CFU/mL, significantly higher than the raw water. The aluminum content was about 10 times higher than that in raw water, and the overall fluctuation was from 0.04 mg/L to 0.12 mg/L. The formation potential of chloroform, dichloroacetic acid and dichloroacetonitrile were slightly lower than that of raw water. After direct reuse of supernatant from the concentration tank to raw water, the turbidity of the raw water and the formation potential of chloroform, dichloroacetic acid and dichloroacetonitrile slightly decreased, the ammonia content did not change significantly, the permanganate index slightly increased, and the aluminum and total bacterial count significantly increased, suggesting that aluminum and total bacterial count were water quality indicators that urgently need to be focused on for the reuse of supernatant from concentration tanks. Based on the continuous operation study of the pilot scale plant, it was found that the direct reuse of the supernatant from the concentration tank had no significant effect on the effluent quality of the carbon sand filter, and the direct reuse of the supernatant from the concentration tank would not lead to the enrichment of aluminum in the sludge water of the sedimentation tank and the backwash water of the carbon sand filter.ConclusionThis paper indicats that the supernatant from the concentration tank can be directly reused in the process of drinking water treatment.

ObjectiveThe water source of the Pearl River West Channel, as an important backup water source in Guangzhou, has been significantly improved through water environment treatment in recent years, and now has the possibility of being used as a formal source of drinking water. Clarifying the water quality characteristics and treatment efficiency of the water source of the Pearl River West Channel can provide process, technology and parameter support for Guangzhou to launch the water source of the Pearl River West Channel in the future.MethodsIn this study, the raw water quality characteristics and the removal efficiency of the whole process were studied by taking the water source of the Pearl River West Channel as the test raw water, and the water quality characteristics and treatment efficiency of the raw water source were clarified.ResultsThe water source of the the Pearl River West Channel was a slightly polluted water source with high turbidity, chromaticity, organic matter, inorganic salt and other pollutants; Biological contact oxidation pretreatment could effectively remove inorganic salts from water, with a maximum removal rate of 60.60%; The conventional treatment of flocculation sedimentation filtration had a good removal effect on various pollutants in water, with removal rates of turbidity and chromaticity exceeding 80%, and organic matter and inorganic salts maximum removal rate of 41.21% and 89.72%, respectively; Adding advanced treatment could further remove pollutants from water and improve the quality of drinking water. Among them, ultrafiltration nanofiltration had the best removal effect, with a removal rate of over 80% for turbidity and chromaticity, while maximum removal rate of organic matter and inorganic salts were about 84.12% and 71.95%, respectively; Next was ultraviolet advanced oxidation, which had a maximum removal rate of organic matter and inorganic salts 42.65% and 37.45% respectively; Ozone activated carbon had relatively poor performance, with removal rates ranging from 25.46% to 35.99% for maximum removal rate of turbidity and chromaticity, and about 20% and 30% for organic matter and inorganic salts, respectively.ConclusionThe water source of the the Pearl River West Channel is a slightly polluted water source. Pretreatment + conventional treatment can remove most of the pollutants in the raw water. Increasing advanced treatment can further remove the pollutants in the water and improve the quality of drinking water. Overall, the removal effect and operating cost of different advanced treatment processes generally show a trend of ultrafiltration nanofiltration>ultraviolet advanced oxidation> ozone activated carbon.

ObjectiveFilamentous bulking is one of the most severe operational issues in wastewater treatment plants (WWTPs), which typically causes reduction of treatment capacity and excessive effluent suspended solids. Particularly for sequencing batch processes, the normal operation would be destructed by filamentous bulking due to failed sludge-water separation in biological systems. Therefore, controlling the excessive growth of filamentous bacteria is significantly important for stable operation of WWTPs.MethodsThis paper introduced a case study of cyclic activated sludge system (CASS) process WWTP in a certain county town with a design capacity of 20 000 m3/d, that experienced severe sludge bulking due to the combined effects of influent load shock and low influent temperature in winter. The effluent COD, ammonia nitrogen and TN parameter were exceeded. In order to restore normal operation of CASS process, a two-phase system adjustment was implemented. In phase I, the measures such as polyacrylamide (PAM) dosing, extended aeration duration, and dissolved oxygen (DO) control were employed, but without achieving significant improvement in operation effects. In phase Ⅱ, a comprehensive measures were implemented, including accelerated sludge wasting, manual floating sludge removal, operation sequence optimization, influent loading rate stabilization, aeration and DO strictly controlling. Fortunately, the sludge bulking was effectively controlled.ResultsThe settling velocity (SV30) was reduced from 98% to below 70%. And the major effluent parameters decreasing from averages (COD: 37.14 mg/L, ammonia nitrogen: 3.60 mg/L, TP: 0.33 mg/L, TN: 16.12 mg/L) to compliant levels. System recovery was achieved within 40 days, and the treatment capacity was restored from 14 000 m3/d during the commissioning period to designed 20 000 m3/d.ConclusionLow temperature constitutes the primary factor for filamentous bulking. And influent loading rate shock directly causes effluent quality non-compliance. Meanwhile, high sludge loading rate combined with sustained low DO levels promotes filamentous bacteria proliferation as indirect contributing factors. It is recommended that WWTPs should promptly discharge and replace sludge and adjust their operating conditions before entering winter to inhibit the growth of filamentous bacteria. In daily operation, it is necessary to arrange reasonable operating procedure and strict control of parameters such as loading rate, DO and sludge retention time (SRT) to keep stable operation in WWTPs.

ObjectiveAccurately identifying water intrusion points outside the municipal wastewater network is an important basis for the development of quality and efficiency improvement of wastewater treatment plants (WWTPs). Compared with traditional pipe network investigation method, the internet of things (IOT) technology can quickly lock problem areas and improve wastewater treatment efficiency.MethodsTaking a municipal WWTP in Shanghai as the research object, this paper proposed a real-time monitoring of water quality and quantity based on IOT sensing and a classification diagnosis method for drainage zones, analyzed the water quality changes of main wastewater pipes and branch pipes in the study area, and identified the problem areas with external water intrusion.ResultsThe average influent volume of the WWTPs from February 2021 to June 2022 was 31 082 m3/d, and the maximum daily inflow volume was 1.85 times that of the minimum daily influent volume. By comparing the data of regional water supply and wastewater volume, it can be seen that the actual monthly wastewater volume was always greater than the calculated theoretical wastewater volume, with a difference ranging from 6 725.58 m3/d to 18 107.11 m3/d. The influent volume and water quality of the WWTPs were greatly affected by rainfall. The influent and quality of WWTPs were greatly affected by rainfall. Compared with dry days in non-flood season, the influent rate in rainy season increased by 16.25%, the COD concentration decreased by 14.45%, the ammonia nitrogen concentration decreased by 40.26%, the total phosphorus concentration decreased by 49.84%, and the total nitrogen concentration decreased by 22.56%. The study area was divided into 18 sub-regions of drainage, and water quality online monitoring equipment was installed on the main wastewater trunk pipes and main branch pipes. Among the three main wastewater pipes, during most monitoring periods, the COD quality concentration of the north area trunk pipe was below 100 mg/L, and the phenomenon of external water intrusion was obvious, and the Laozhen District and the Lake District drainage area within the scope of the wastewater pipe network damage led to the mixing of external water into the wastewater pipe network, which was one of the main reasons for the influent BOD5 concentration of the downstream WWTP to be lower than 100 mg/L.ConclusionThrough the classification method, the detection efficiency of external water intrusion in wastewater network can be improved, the cost of problem tracing in pipe network can be reduced, and the quality and efficiency of WWTP can be improved.

ObjectiveTo reduce the dosage of coagulants and coagulants in coagulation, thereby reducing the production of coagulation sludge, a microsand loading flocculation experiment was conducted.MethodsBased on the research findings from multiple studies, the effects of coagulant types and concentrations, anionic polyacrylamide (PAM), microsand particle size, microsand dosage, and sedimentation time on Total Phosphorus (TP) removal are systematically analyzed below, along with orthogonal test result evaluating the influence hierarchy of these factors.ResultsUnder the same coagulant concentration, the removal effect of polymeric ferric sulfate (PFS) on TP was due to polymeric aluminum chloride (PAC) and ferric trichloride (FeCl3); the higher the concentration of PFS, the higher the removal rate of TP. The removal of TP showed a trend of first increasing and then decreasing with the increase of PAM concentration. The smaller the particle size of the added microsand, the higher the removal of TP. When the precipitation time was less than 40 minutes, the removal of TP increased with the increase in precipitation time. When PFS was 40 mg/L, PAM was 1.5 mg/L, the particle size of microsand was 50 m, the amount of microsand dosage was 4.0 g/L, and the sedimentation time was 40 min, the removal of TP could reach 81.46%, and the TP concentration decreased from 0.5 mg/L to 0.093 mg/L. From the result of orthogonal experiments, the influence of each experimental factor on TP removal from high to low was PFS concentration, microsand dosage, PAM concentration, and sedimentation time. The flocs formed by PFS and PAM as coagulants had smaller particle sizes than the flocs adding micro sands, larger flocs were more conducive to sedimentation and could improve the removal of TP.ConclusionThe study reduces the dosage of coagulant by adding microsand, effectively improves the TP treatment efficiency and reduces the economic cost, which provides a theoretical basis for engineering application.

ObjectiveDue to the uneven development of urban areas, the wastewater load borne by wastewater treatment facilities in different regions varies. This has led to some wastewater treatment plants (WWTPs) operating beyond their design capacity, resulting in wastewater overflow, while others are running at low capacity, incurring high operational costs. In a certain watershed in Beijing, the reclaimed WWTP A and B were located in the upstream and downstream sections, respectively. The wastewater volume and quality were imbalanced between the two WWTPs, with the reclaimed WWTP A receiving more water than its design capacity, while the reclaimed WWTP B received less than its designed capacity.MethodsTo ensure a high rate of wastewater collection and treatment, reduce overflow, and lower operational costs, a wastewater distribution network was built between the two WWTPs.ResultsThis study examined the environmental and economic benefits of the wastewater allocation between the two reclaimed WWTPs. The analysis showed that the wastewater distribution effectively reduced upstream overflow, generating positive environmental benefits. The allocation had little impact on the operating costs of the reclaimed WWTP A, while it significantly improved the water quality at the reclaimed WWTP B, enhancing its carbon/nitrogen ratio (C/N) and reducing its operational costs. The overall costs of both plants benefit from the water allocation.ConclusionTherefore, wastewater distribution is an effective measure for improving both environmental and operational efficiency in WWTPs with imbalanced influent loads that are in close proximity to each other.

ObjectiveThis paper aims to explore the environmental and economic value of reusing industrial waste, particularly using steel industry pickling iron mud as a raw material to prepare efficient catalysts through hydrothermal method for water treatment, especially for removing organic pollutants such as tetracycline hydrochloride (TCH) from water. The goal is to promote resource recycling and reduce environmental pollution.MethodsHydrothermal method was employed to convert pickling iron mud into CoFe2O4 composite catalyst, and a composite catalyst/peroxymonosulfate (PMS) advanced oxidation system was constructed. The reaction system was optimized by adjusting pH, catalyst dosages, and PMS dosages. The degradation mechanism was analyzed using free radical trapping experiments.ResultsUnder optimal conditions (pH value was from 3.5 to 10.0, composite catalyst dosage of 0.3 g/L, PMS dosage of 0.6 g/L), the removal rate of TCH reached 80% after 30 minutes of reaction. The CoFe2O4 composite catalyst maintained high catalytic activity and stability after multiple uses. Free radical trapping experiments confirmed that ·OH and SO4·&#x2212; were the main active species responsible for TCH degradation, indicating that the system efficiently degraded pollutants through a free radical oxidation mechanism. This paper successfully achieved the high-value utilization of industrial waste pickling iron mud. The prepared CoFe2O4 composite catalyst demonstrated excellent catalytic performance and stability in the advanced oxidation system.ConclusionThis technology not only reduces catalyst preparation costs but also provides a green and sustainable solution for water pollution control, contributing significantly to promoting resource recycling and environmental protection.

ObjectiveTo control combined sewer overflow (CSO) pollution, this study explores a design method for storage tank volume in CSO pollution control.MethodsTaking the ecological park area of Dongguan City as the research object, based on the storm water management model (SWMM), the drainage channels and related catching-up zones were generalized to construct the regional CSO hydraulic model, and the influence of the designed volume of the storage tank on the pollution control effect of the CSO under typical hydrological year conditions, annual total overflow volume, annual total overflow frequency and the annual total overflow COD load as the indices to evaluate the pollution characteristics of the CSO.ResultsIncreasing the volume of the storage tank could enhance the control rate of overflow water volume. However, due to the diminishing marginal benefit, there exised an optimal point. Before this point, increasing the volume of the storage tank could significantly improve the control effect of overflow pollution. After the optimal point, further increasing the volume of the storage tank had limited effect on improving the control effect of overflow pollution. In this study case, the optimal volumes of the storage tanks corresponding to the four drainage channels were 8 000, 10 000, 15 000, and 1 000 m3, respectively. The control rates of the overflow pollutant load and overflow water volume in the corresponding study area were 62.4% and 51.8% respectively. Compared with the working condition without storage tanks, the number of overflows in the following year was reduced by 43.ConclusionThere is an initial scouring effect in the pollution of CSO. When the volume of the storage tank is the same, the control rate of the storage tank for the pollutant load of the overflow is higher than that for the overflow water volume. Adopting the mathematical model method that can reflect the real confluence process is conducive to seeking a technical and economic balance point between the pollution control efficiency of the storage tank and the construction scale. The design method proposed in the research is a beneficial supplement to the current technical specifications' design guidelines for the volume of CSO pollution control and storage tanks.

ObjectiveNitrogen and phosphorus pollution is commonly observed in the rivers of a city in southern China during rainy seasons. It is found that the main sources of pollution in this river are the rainfall runoff from surrounding roads and vegetable farmland alongshore the river. To further determine the contribution rate of farmland rainfall runoff to the pollution of the river, this study monitors and analyzs the output patterns and characteristics of pollutants of rainfall runoff from typical vegetable farmland alongshore the river.MethodsIn this study, a typical vegetable farmland along a river in a southern city was selected as the research object, and rainfall runoff was monitored from June 2022 to August 2022, including water level and flow velocity, and sampling points were set up to collect rainwater runoff, and the pH value of the water samples was adjusted to below 2 by adding acid to the site, and the suspended solids (SS), total phosphorus (TP), phosphate (PO43&#x2212;), total nitrogen (TN), ammonia nitrogen and other indices of the water samples were subsequently detected and analyzed.ResultsIt was showed that TP was the main pollutant in farmland rainfall runoff, with the average and maximum mass concentrations of 6.91 mg/L and 13.32 mg/L, respectively. Dissolved inorganic phosphorus was the main form of phosphorus discharge, accounting for 74% of TP on average. When rainfall scoured farmland, the initial scouring intensity of each pollutant was ranked as ammonia nitrogen> TP > SS > TN > dissolved organic matter (DOM), and the initial scouring effect was more likely to occur when continuous rainfall scoured farmland.ConclusionThrough the study of this region, it is found that dissolved inorganic nitrogen and inorganic phosphorus in rainfall runoff are the main forms of nitrogen and phosphorus in runoff, and the main task of controlling agricultural non-point source pollution in this region is to reduce phosphorus emissions.

ObjectiveAddressing technical challenges in integrating sewage pipelines into underground utility tunnels during China's accelerated urbanization, including gravity-flow slope gradient matching difficulties, prominent pipeline crossover conflicts, and insufficient durability in highly corrosive environments. This study systematically explores optimized design solutions using a new town construction project in Zhengzhou City as a representative case.MethodsFor slope gradient cooperative control, a coordinated design harmonizing utility tunnel longitudinal slope, sewage pipe slope gradient, and road slope gradient are established, with finite element analysis optimizing support pier spacing and structural parameters. For corrosion protection, an independent sewage compartment layout employs ductile iron pipes lined with epoxy ceramic coatings combined with fiberglass-reinforced plastic-encapsulated inspection well nodes, creating a "rigid substrate + flexible protection" composite anti-seepage system. The intelligent safe system integrates variable-frequency ventilation, distributed toxic gas monitoring, and liquid-level-linked drainage devices to form a multi-dimensional protection mechanism.ResultsThe project realizes that the longitudinal slope gradient of gravity flow sewage pipeline is controlled within ±0.1% accuracy of deviation from design. The leakage of the pipeline corridor is reduced to 0.05 L/(m2·d). Temperature fluctuation in the chamber in a single day is no more than 2 ℃. Methane volume fraction is controlled within 1%, which is below the explosion threshold, and hydrogen sulfide mass concentration is controlled within 5 mg/L. The project significantly reduces the accident rate of pipe burst and leakage caused by corrosion and sedimentation of sewage pipes.ConclusionThe developed "three-dimensional slope gradient coupling design-composite anti-corrosion system-intelligent operation and maintenance" framework effectively resolves technical bottlenecks for wastewater integration in Zhengzhou's alluvial strata utility tunnels. Its spatially adaptive design, long-term anti-corrosion techniques, and smart resilience management model provide a replicable paradigm for utility tunnel construction in alluvial plains.

ObjectiveTaking a 1.2 million ton per year differentiated polyester project as an example, this paper analyzes the design, installation, commissioning, and operational effectiveness of a 3 000 m3/d wastewater treatment plant (WWTP) at a chemical fiber enterprise in Jinzhou City. Aiming at the characteristics of the wastewater [poor biodegradability (BOD5/COD<0.3)], high organic matter concentration (average COD mass concentration is 8 000 mg/L), and containing refractory aromatic compounds and trace acetaldehyde (a highly efficient and stable advanced treatment process system is constructed to overcome the limitations of traditional biological method for low BOD5 to COD ratio wastewater while achieving dual goals of wastewater resource reuse and energy recovery.MethodsThe designed adopts classified pretreatment + dissolved air flotation + homogenization acidification (enhancing biodegradability) + upflow anaerobic sludge blanket reactor [UASB, organic loading is 8 kg COD/(m3·d)] + two-stage anoxic-oxic (AO, strengthening nitrogen and phosphorus removal) + high-efficiency sedimentation (chemically enhanced phosphorus removal) + fiber disk micro-filtration + ozone catalytic oxidation (degrading refractory organics) + ultrafiltration and reverse osmosis (ensuring reuse water quality). Key design parameters of major structures are systematically introduced.ResultsOperational result demonstrates that the effluent COD concentration is consistently below 30 mg/L. All effluent indices (including ammonia nitrogen and total phosphorus) surpass the Grade A standards of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918—2002). Simultaneously, the effluent meets Class Ⅳ criteria of the Environmental Quality Standards for Surface Water (GB 3838—2002). COD removal efficiency reaches 99%, with over 80% of the effluent reused, at a treatment cost of 2.63 yuan/m3.ConclusionThis wastewater treatment process performs effectively in practical applications, efficiently treating high-concentration, refractory wastewater from chemical fiber enterprises. It exhibits advantages including high treatment efficiency, operational stability, strong resistance to shock loads, and cost-effectiveness, providing valuable guidance for upgrading or expanding similar WWTPs.

ObjectiveAssessing the uncertainty of ion chromatography in determining the content of perchlorate in drinking water to improve the accuracy and scientificity of detection result.MethodsBased on the evaluation principles and method of uncertainty measurement, this paper analyzed and discussed various factors that affected measurement, including standard substances, standard curve fitting, standard solution preparation process, instrument itself, sample repeatability measurement, sample stability, etc. Simultaneously, this paper compared and evaluated the repeatability measurements of standard solutions and samples at different times. And used WPS Office 2023 software for data organization and statistical analysis, analyzed and calculated the mean values, test standard deviation, and uncertainty values. The uncertainty components were statistically described using the composition ratio.ResultsWhen both the standard solution and the sample were measured once, a large degree of uncertainty was introduced. The number of measurements gradually increased, and the introduced uncertainty values gradually decreased. By parallel measuring the standard point 3 times and the sample 6 times, the determination result of perchlorate in the sample was 9.68 g/L, and an extended uncertainty was 0.93 g/L (the inclusion factor k was 2).ConclusionThe main sources of uncertainty in this method are calibration curve fitting (39.34%) and standard solution preparation process (19.36%), followed by standard substances (15.21%) and sample repeatability measurements (10.34%). Suggestions and strategies for reducing uncertainty have been proposed.

ObjectiveWith the extensive use of antibiotics, antibiotic resistance genes (ARGs) are frequently detected in water environments, and the associated health risks of water quality have attracted increasing attention. Traditional wastewater treatment processes are ineffective in removing these contaminants, making ultraviolet (UV)-advanced oxidation processes (AOPs) a research hotspot, particularly regarding their potential to reduce ARGs in water environments.MethodsThis paper reviews the combinations of UV with hydrogen peroxide (H2O2), persulfate (PS), chlorine (Cl2), Fenton reagent, and titanium dioxide (TiO2), which have achieved effectively removal of ARGs to various degrees. It focuses on analyzing their working principles, reduction mechanisms, and reduction effects, and further discusses how different UV-AOPs processes generate highly reactive oxygen species [such as hydroxyl radicals (·OH), sulfate radicals (SO4·&#x2212;)] to disrupt cell surfaces and deoxyribonucleic acid (DNA) structures, thereby inactivating bacteria and eliminating ARGs.ResultsAmong them, the UV/H2O2 process utilizes hydroxyl radicals (·OH) to degrade ARGs, UV/PS exhibits a broader pH range of applicability, UV/Cl2 enhances ARGs removal through the photolysis of Cl2 to generate reactive species, UV/Fenton reactions generate a large amount of ·OH with high removal efficiency, and UV/TiO2 inhibits the spread of ARGs through photocatalytic production of reactive oxygen species. By comparing the application effects in different water environments, the article explores the advantages and disadvantages of these processes and their feasibility in practical applications. The results show that although UV-AOPs demonstrate significant effects in reducing ARGs in water environments, the degradation efficiency of different processes is influenced by various factors such as water quality conditions, oxidant dosages, and process configuration.ConclusionOverall, UV-AOPs represent a promising water treatment technology that provides an effective mean for reducing ARGs. However, in practical applications, further research is needed on the synergistic effects of different processes and how to optimize various parameters to improve treatment efficiency and ensure stable performance in variable water environments, while minimizing potential secondary pollution. This aims to provide technical references for water environment protection and public health safety.

ObjectiveMicrobial contamination in drinking water distribution system is a critical factor affecting water supply safety, particularly in multi-source mixed water supply areas. Dynamic water quality variations and hydraulic fluctuations further complicate microbial community structures. This study aims to explore the effects of such fluctuations on microbial composition in blended supply zones.MethodsThis paper investigated blended water supply zones in Beijing, where water samples were collected from multiple locations to analyze the spatial variation of water quality parameters. In addition, high-throughput sequencing was applied to characterize the microbial community structures associated with planktonic and particle-attached fractions.ResultsResults indicated that electrical conductivity, residual chlorine, turbidity, and adenosine triphosphate (ATP) concentrations fluctuated across sampling points, highlighting the impact of blended water supply on water quality stability. Correlation analysis indicated that certain high-abundance microbial taxa were significantly associated with water quality parameters (p<0.05), with particle-associated microorganisms showing higher sensitivity to water quality fluctuations. Alpha diversity analysis showed that while the species richness of particle-associated communities was slightly higher than that of planktonic communities, the difference was not statistically significant (p>0.05), likely due to chlorine disinfection reducing the disparity between the two and the protective role of particulate matter in providing microbial refugia. Beta diversity analysis revealed that microbial community differentiation was primarily driven by water quality fluctuations associated with mixed water supply rather than by microbial phase states. Differences in microbial composition between planktonic and particle-associated communities were observed, with particulate matter enhancing the selective influence of water source variability and affecting the distribution of low-abundance microbial flora. The abnormal proliferation of Ralstonia spp. at specific sites intensified community divergence, while the high relative abundance of uncultured microbial flora suggested that unstable pipe network water quality could pose a potential risk for pathogen transmission.ConclusionThis paper provides insights into the spatial heterogeneity and potential risks of microbial communities in blended water supply systems, highlighting the need for enhanced dynamic monitoring of key water quality parameters and improved particulate control, thereby offering a scientific basis for water quality monitoring and management strategies in drinking water distribution system.

ObjectiveRecently, nitrate contamination still exists in water bodies in China, which not only leads to frequent eutrophication, but also potentially endangers human health. Therefore, this study aims to effectively address nitrogen-containing water pollution issues.MethodsIn the experiment, autotrophic denitrification process of elemental sulfur powder was combined with gravity-driven dynamic membrane bioreactor technology to investigate the denitrification potential and membrane fouling behavior of the coupling system at different hydraulic retention times (HRTs).ResultsWhen the initial sulfur powder/sludge ratio was 4 and the influent NO3&#x2212;&#x2212;N was approximately 22 mg/L, the HRT was shortened from 12 h to 4 h, and the removal rate of NO3&#x2212;&#x2212;N reached 100% in a short time. However, when the HRT was 2 h, the operating effect of the reactor began to deteriorate, the NO3&#x2212;&#x2212;N removal rate decreased significantly, and the accumulation of NO2&#x2212;&#x2212;N was serious. During the whole operation, the transmembrane pressure difference increased from 0 to 1 470 Pa. Meanwhile, the disparity in pollutant concentration between supernatant and effluent revealed that the dynamic membrane exhibited notable secondary removal performance of NO3&#x2212;&#x2212;N, indicating that the dynamic membrane had formed stably and had good metabolic activity. The observation of dynamic membranes at different stages by scanning electron microscopy showed that a large number of bacilli and filamentous bacteria adhering to the sulphur powder accumulated within the dynamic membrane mesh, ultimately resulting in severe irreversible membrane contamination.ConclusionThe sulfur-autotrophic dynamic membrane bioreactor proposed in this study demonstrates high denitrification performance and resilience to shock loads. The findings are expected to provide a certain technological foundation for the development of green and low-consumption wastewater denitrification technologies.

ObjectiveThe pollution caused by municipal pumping stations releasing rivers during rainy days has become one of the main factors affecting the sustained and stable improvement of river water quality in the central urban area of Shanghai. In order to reduce the impact of pumping stations on the water environment of rivers, relevant research has been carried out on the elimination of pollution caused by pumping stations discharging water into the river in the central area of Shanghai based on sluice scheduling. This study can provide technical support for promoting the continuous and stable improvement of river water quality and creating a "happy river and lake" that satisfies the people.MethodsBased on comprehensive foundational data, this study constructed a high-precision integrated hydraulic model of Suzhou Creek and its municipal pumping stations along the riverbanks, and conducted calibration and validation of the model using measured data. Multiple operational scenarios were designed by considering factors including sluice gate regulation capacity, tidal fluctuations, and rainfall characteristics, with the objective of rapidly restoring water quality in discharge zones following stormwater release. Through multi-scenario comparative analysis using the model, optimized pump-gate operation strategies applicable to diverse rainfall scenarios were proposed.ResultsModel simulation analysis demonstrated that under the optimized operation strategy, Suzhou Creek achieved greater daily average discharge capacity, enhanced water exchange efficiency, and a significantly shortened duration of water quality impacts induced by pumping station discharges. Taking the heavy rainfall scenario as an example, Suzhou Creek's daily discharge volume under the optimized strategy doubles compared to current levels, reaching 4.49 million m3. The water renewal cycle is reduced from 2.47 days to 1.08 days, while the duration of water quality impacts caused by pumping station discharges can be shortened by over 30%.ConclusionThrough integrated analysis of historical data and model simulation validation, the optimized sluice gate operation strategy proposed in this study for post-discharge scenarios at municipal pumping stations along Suzhou Creek demonstrates operational feasibility without flood prevention warning or rainstorm warning, achieving rapid pollution mitigation following pumping station discharges.

ObjectiveWith the development of the Zhijiang region, the wastewater volume in the region is expected to reach 130 000 m3/d in the near future and 160 000 m3/d in the long term. To meet the demand for wastewater treatment in the region, a new wastewater treatment plant (WWTP) needs to be built to receive 80 000 m3/d of wastewater in the near future (another 50 000 m3/d will be transported to the Qige WWTP through existing pipelines), and 160 000 m3/d of wastewater in the long term. At the same time, considering that the project is located in an important area of the Zhijiang Resort, with high land value and high environmental requirements, in order to minimize land use and eliminate the nimby effect, the project adopts a fully underground construction form.MethodsA new Hangzhou Zhijiang WWTP with a total capacity of 160 000 m3/d and a recent capacity of 80 000 m3/d will be constructed entirely underground. The wastewater treatment process adopts pre-treatment + pre-high-efficiency sedimentation tank + pre-denitrification biological filter + nitrification biological filter + post-denitrification biological filter + post-high-efficiency sedimentation tank + filter cloth filter + chlorination contact tank. The main pollutants COD, BOD5, and TP emissions in the effluent will comply with the Class Ⅲ water quality standard of the Environmental Quality Standards for Surface Water (GB 3838—2002). Ammonia nitrogen will comply with the Class Ⅲ water quality standard (1.0 mg/L) of the Environmental Quality Standards for Surface Water (GB 3838—2002) from April to October each year, and comply with the Class Ⅳ water quality standard (1.5 mg/L) of the Environmental Quality Standards for Surface Water (GB 3838—2002) from November to March of the next year. SS of effluent is no more than 5 mg/L, TN of effluent is no more than 10 mg/L, all effluent indices are superior to the Class A standard of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918—2002) The sludge treatment process includes mechanical concentration and dewatering + low temperature drying, and the sludge is transported out after the water content is no more than 45%.ResultsThe land occupation indicator per ton of water in the entire WWTP is only 0.18 m2/(m3·d), which is 1/5 of the national land occupation indicator for WWTP construction. The WWTP has been in operation for nearly a year, and the effluent can stably meet the designed standard. The effluent COD mass concentration is below 20.0 mg/L, with a removal rate of 93.3%; the effluent BOD5 mass concentration is below 4.00 mg/L, with a removal rate of 97.3%; the effluent SS mass concentration is below 5.0 mg/L, with a removal rate of 97.5%; the effluent TN mass concentration is below 10.0 mg/L, with a removal rate of 75%; the effluent ammonia nitrogen mass concentration is below 1.00 mg/L, with a removal rate of 96.7%; the effluent TP mass concentration is below 0.20 mg/L, with a removal rate of 95%.ConclusionWhen the combined process of biological filter is used for secondary treatment, the effluent can stably meet the designed standards of effluent, and the occupied area is extremely small, making it suitable for engineering projects with high treatment requirements and limited land.

ObjectiveTo make up for the deficiencies of traditional microbial determination method in water, a standard method for detecting the adenosine triphosphate (ATP) content of microorganisms in water is established. This enriched the detection system of microbial indices in water and provides a rapid detection means, thereby enhancing the detection capability of water quality in laboratories.MethodsBased on the method of the American Society for Testing and Materials——Standard Test Method for Adenosine Triphosphate (ATP) Content of Microorganisms in Water (ASTM D4012—23a), a standardized ATP determination procedure had been established. Multiple laboratories had verified the limit of detection, lower limit of determination, precision, and accuracy. This method had also been applied in the detection of the entire water supply process and ice slurry cleaning of water supply pipelines.ResultsThe verification result showed that the method detection limit was 0.170 pg/mL, the lower limit of determination was 0.680 pg/mL, the range of the relative standard deviation was from 0.6% to 17.5%, the range of relative error was from -5.7% to 8.6%, the range of adding standard recovery was from 105.7% to 125.4%, and the results of the blank test were all less than the method detection limit. The method application showed that the ATP standard method could reflect the changes in microorganisms during the water purification process, the characteristics of water age in the water supply pipeline network, and the degree of microbial contamination on the inner wall of the pipeline.ConclusionThe method has the characteristics of a wide detection range, large concentration span, accurate data, convenient steps, and low waste and environmental protection. It can reflect the differences in water quality, water purification processes, and water age. And it is suitable for the microbial total quantity monitoring of the entire water supply process. It has been officially released as a group standard ——Determination of Microorganisms Content in Water-Adenosine Triphosphate (ATP) Bioluminescence Method (T/SAWP 003—2024) and can serve as an effective supplement of the microbial indices determination system in water.