Sewage Research Articles

Study on the implementation and operational cost calculation of by-product utilization system in sewerage management

Study on the implementation and operational cost calculation of by-product utilization system in sewerage management

Molecular Characterization and Phylogenetic analyses of Rotaviruses Circulating in Municipal Sewage and Sewage-Polluted River Waters in Durban Area, South Africa.

Globally, rotavirus continues to be the leading etiology of severe pediatric gastroenteritis, and transmission of the disease via environmental reservoirs has become an emerging concern in developing countries. From August to October 2021, a total of 69 samples comprising 48 of raw and treated sewage, and 21 surface waters, were collected from four Durban wastewater treatment plants (DWWTP), and effluent receiving rivers, respectively. Rotaviruses recovered and identified from the samples were subjected to sequencing, genotyping, and phylogenetic analysis. Of the 65 (94.2%) rotavirus-positive samples, 33.3% were from raw sewage, 16% from activated sludge, 15.9% from final effluents, and 29.0% were from the receiving river samples. A total of 49 G and 41 P genotypes were detected in sewage while 15 G and 22 P genotypes were detected in river samples. G1 genotype predominated in sewage (24.5%) followed by G3 (22.4%), G2 (14.3%), G4 (12.2%), G12 (10.2%), G9 (8.2%), and G8 (6.1%). Similarly, G1 predominated in river water samples (33.3%) and was followed by G2, G4 (20.0% each), G3, and G12 (13.3% each). Rotavirus VP4 genotypes P[4], P[6], and P[8] accounted for 36.6%, 29.3%, and 9.8%, respectively, in sewage. Correspondingly, 45.5%, 31.8%, and 13.6% were detected in river samples. The G and P genotypes not identified by the methods used were 2.1% versus 24.3% and 0.1% versus 9.1% for sewage and river water samples, respectively. Sequence comparison studies indicated a high level of nucleotide identity in the G1, G2, G3, G4, G8 VP7, and P[4], P[6], and P[8] VP4 gene sequences between strains from the environment and those from patients in the region. This is the first environmental-based study on the G and P genotypes diversity of rotavirus in municipal wastewater and their receiving rivers in this geographical region. The high similarity between environmental and clinical rotavirus strains suggests both local circulation of the virus and potential exposure risks. In addition, it highlights the usefulness of sewage surveillance as an additional tool for an epidemiological investigation, especially in populations that include individuals with subclinical or asymptomatic infections that are precluded in case-based studies.

Pollution Status and Research Progress of Azole Fungicides in Environment

Because of its broad spectrum, low toxicity and high efficiency, azole fungicides are widely used in various types of agricultural production, personal care products, medicines and material surface protection, which inevitably makes them enter various environmental media through surface runoff, rainfall, atmospheric volatilization and farmland irrigation, posing potential threats to the surrounding environment and human health. In rural areas, fungicides sprayed on crops are usually difficult to play a full role, most of which tend to enter the surface by wet sedimentation and other ways, and then directly into the environment through surface runoff. It is well known that China has been a big agricultural producer since ancient times, and the annual application amount of pesticides is as high as 500,000-600,000 tons, ranking first in the world. As an important part of pesticide products, the annual sales of fungicides account for about 25% of the total sales of pesticides, which makes a large number of fungicides into the environment, causing pollution to the surrounding environment. In urban areas, the population density is large, and the large use of all kinds of personal care products makes a considerable part of fungicides enter the municipal pipe network with domestic sewage. At the same time, the fungicides used to protect the urban vegetation landscape will also flow into the municipal pipe network with rainfall and eventually enter the sewage treatment plant. At present, most of the sewage treatment process design, whether domestic or foreign, considers the removal of conventional organic matter, and the removal rate of trace organic matter such as fungicides is often very low, which makes the residual fungicides in sewage eventually return to the environment.

The effect of chemical oxygen demand of domestic wastewater on workability, mechanical, and durability of self- compacting concrete

Due to worldwide water scarcity, especially in arid regions, and the substantial use of drinking water in concrete production, the consideration of gray water usage is growing. However, wastewater contamination adversely affects concrete's mechanical strength and durability, with Chemical Oxygen Demand(COD) as one of the indicator. In the present work, the effect of COD of different types of domestic wastewater on workability, mechanical, and durability properties of self-compacting concrete (SCC) with 400 kg/m3 and 440 kg/m3 of cement, and water-to-cement ratios of (w/c) 0.36 and 0.5 for 12 different SCC mixture designs were investigated. The results of the experiments indicated that increasing the COD of domestic wastewater negatively impacts the workability of fresh concrete. Additionally, as the COD of the wastewater increases, the compressive strength of SCC decreases at 7 and 28 days when using raw sewage, sewage sludge, and artificial wastewaters. However, by 90 days, the compressive strength showed no significant difference compared to SCC made with tap water. With increasing COD of wastewater, the 28-day tensile strengths of SCC decreased by 6–10 %. The COD of wastewater did not significantly affect the flexural strength. However, the fracture toughness, at a water-cement ratio (w/c) of 0.5, decreased with increasing COD, reaching a reduction of 36 % at a COD of 940 mg/L. As the COD concentration rises, water absorption increases. In SCC samples containing sludge water and raw sewage, capillary water absorption was at its maximum due to the presence of impurities, as well as organic and mineral materials.

NUTRITIONAL STUDIES ON FISH CATLA CATLA FOUND IN GANGA RIVER WITH HYDROBIOLOGICAL STUDIES

Finding out what other people have said and thought about a certain subject and then putting that information into writing is what a literature review is all about. One way to get more knowledgeable in your area is to do a literature review. Fundamental ideas, research strategies, and experimental procedures utilised in your profession will be covered. Discover real-world challenges. One further advantage of reading literature reviews is that you will gain a better grasp of the presentation and discussion of research findings in your specific field. Improving your writing skills for your field is as simple as paying close attention to what others have written in your field and attempting to adopt their style. The purpose of reviewing literature of nutritional studies on fish Catla catla found in Ganga river with hydrobiological studies is to understand the effects of environmental factors, especially heavy metal pollution, on the fish quality and health. Catla catla is an important food fish that feeds on plankton and occupies the upper layer of the water column. It is widely distributed in India and other South Asian countries. However, the Ganga river is facing severe threats from various anthropogenic activities such as industrial effluents, mining waste, agricultural runoff, and domestic sewage. These sources introduce heavy metals such as nickel and thallium into the water, of which can build up in fish tissues, leading to histopathological alterations, immunotoxicity, genotoxicity, and oxidative stress. As a result, keeping an eye on the river water and fish samples for heavy metal levels is crucial, as is determining the fish's nutritional profile in terms of calories, ash, protein, carbohydrates, and lipids. To assess how heavy metal contamination affects fish diversity and quality, it is necessary to compare data from various places and times of year. Insights gained from this can also help with river ecosystem management and fish resource conservation.Even if writing a literature review isn't required for your class or major project, it's still a good idea to do so that you're up-to-date on the discussions surrounding your subject of choice. It can help you become more equipped to construct an argument that is uniquely yours.

Efficient biological treatment: Achieving exceptional reductions in pollutants and ensuring environmental compliance

The study assessed the effectiveness of treatment processes in removing organic matter, biogenic compounds and suspended solids at the subsequent treatment stages one of the Polish municipal wastewater treatment plant. In a comprehensive mechanical-biological treatment, for all tested pollution indicators, i.e. biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP) and total suspended solids (TSS), outstanding results, surpassing regulatory standards, were obtained. The achieved average percentage reduction was from 87 % for TN (standard deviation of 2.7 %) to average 99 % for BOD5 (standard deviation of 0.3 %). The observed average BOD5/COD ratio of 0.45 aligned with typical values reported, and the decrease in the ratio to 0.13 after biological treatment underscored the efficacy of these processes in organic compounds decomposition and managing difficult-to-degrade substances. The BOD5/TN values emphasized the effectiveness of the treatment, maintaining well-balanced proportions between organic carbon and nitrogen compounds. Moreover, raw sewage showed notable susceptibility to nitrogen removal, indicated by the highest average BOD5/TN ratio of 6.72, suggesting a high propensity for biodegradation. This study highlighted that the average BOD5/TP value of 56 in raw sewage indicated a significant susceptibility to phosphorus compound removal. The treated sewage consistently adhered to environmental regulations, demonstrating minimal variability in pollution indicators. That underscored the effectiveness of treatment processes in meeting stringent standards and achieving significant reductions in pollutants. Effective sewage treatment is even more significant, because it is possible to reuse treated sewage e.g. for irrigation in agriculture, what contributes to the sustainable water management.

Ecological processes in separated structures of electroactive wetlands: Determinism versus stochasticity

Combined systems are an important direction in electroactive wetlands (EWs) research, with unique advantages in treating high-nutrient wastewater, but neither series nor parallel mode is conducive to system stabilization and performance enhancement. To evaluate the relationships between different series and parallel combined designs and the performance of systems, two combined designs based on two-stage EWs were proposed: pre-multiple parallel (MP) (A) and post-MP (B). The two-stage series design (C) was used as the control. Design A exhibited superior nitrogen (72.81 % ± 0.30 %) and phosphorus (92.78 % ± 0.01 %) removal efficiency as well as power production. There was coupling of shortcut nitrification denitrification (SCND) and anaerobic ammonium oxidation (ANAMMOX) in A, which increased the maximum series current density (27.03 mA/m2) and reduced the internal resistance (39.97 Ω). The pre-MP design increased the stochasticity of microbial community assembly (R2 = 0.8781) in accordance with neutral community model, which led to the enhancement of diversity and the functional potential of the microbial community. Proteobacteria was the dominant phylum of the cathodic microbial community and was mainly present in A, accounting for 38.86 %–65.06 %, and played a dominant role in nitrogen removal. Metabolites mediated information exchange between plants and microorganisms; this signaling rate was more rapid in A, which increased the sensitivity of the organisms to environmental changes. This study offers a new approach for practical treatment of rural domestic sewage and engineering applications of EWs.

Nitrate sources and transformations in a river-reservoir system: Response to extreme flooding and various land use

Nitrate (NO3−) pollution poses a global aquatic threat, promoting eutrophication and endangering human health. Large floods can swiftly drive significant nitrogen load into rivers and downstream water bodies, nevertheless, precisely quantifying NO3− sources in watersheds with complex land use patterns remains challenging. In June 2020, heavy and persistent rainfall triggered severe floods across southeastern China, causing Lake Qiandao, the largest reservoir in this region, to reach its highest recorded level. This study investigated NO3− sources and transformations within the Xin'an River-Lake Qiandao system, particularly focusing on the impact of the catastrophic summer flooding event. Through extensive sampling, we identified a distinct nitrogen concentration gradient: from the pristine Xin'an River source, characterized by 95 % forest cover and consistently low nitrogen levels for the initial 125 km, to a gradual rise as the river traversed human-impacted regions, culminating in peak concentrations within residential and agricultural areas. Isotopic analysis identified a general upward trend in nitrate stable isotope (δ15N–NO3–) associated with the expansion of agricultural and urban lands. Mean values of δ15N–NO3– gradually increased from headwaters and forest-dominant catchments (+2.88 ‰) to agricultural regions (+6.64 ‰) and residential areas (+7.10 ‰). A Bayesian modeling identified that during the flood season, soil erosion and chemical fertilizers were the primary contributors, collectively accounting for 74 % of NO3− sources in the Xin'an River. However, accumulated sewage in tributaries and the overflow of sewage from treatment plants, exacerbated by the flood, significantly impacted Lake Qiandao, particularly in densely populated urban areas, contributing 53 % of the total NO3− input. Additionally, NO3− levels and isotopic values in Lake Qiandao were influenced by a mixture of sources and nitrogen cycling processes, including nitrification and algae assimilation following the flood event. In contrast, during baseflow conditions, the contribution of domestic sewage and livestock wastewaters increased to 41 % in the upper river, while Lake Qiandao remained affected by non-point source pollution, with soil erosion and chemical fertilizers contributing 58 % to the total nitrogen pollution. This study sheds light on the complex dynamics of NO3− dynamics within river–reservoir systems, particularly in the context of extreme flooding, emphasizing the critical need for comprehensive water quality management strategies along the entire watershed.

How does village cadres' quality affect farmers' approach to domestic sewage treatment? Evidence from Jiangxi Province, China

The clean transformation of domestic sewage treatment is essential for addressing the challenges of current rural environmental pollution. Village cadres, as rural leaders, play a crucial role in organizing and coordinating farmers' participation in improving sewage treatment. Although previous studies have highlighted the importance of domestic sewage treatment, research on how rural leaders' qualities influence farmers' sewage treatment practices remains significantly limited. To fill this gap and clarify the relationship between the qualities of village cadres and farmers' participation in domestic sewage treatment, this study focuses on analyzing whether improving the village cadres’ quality can lead to enhanced scientific treatment of rural domestic sewage by farmers. Through linear regression analysis of a sample of rural residents in Jiangxi Province, China, this study demonstrates that the improved quality of village cadres positively affects farmers' scientific treatment of domestic wastewater. The study also finds that farmers' trust in village cadres plays a significant role in aiding high-quality leaders to improve farmers' scientific wastewater treatment behaviors. Moreover, compared to farmers in villages without a representative village council system, those in villages with such a system are more likely to be influenced by high-quality village cadres, thereby improving their wastewater treatment practices. Based on these findings, this article offers practical implications for policymakers and researchers aiming to strengthen rural environmental governance and sustainable development efforts.

Traceability of gushing water in the MiddleRoute of the South-to-North Water Diversion (Beijing section) through the river area

To trace the origin of the gushing water in the riverine area of the Beijing section of The Middle Route of South-to-North Water Diversion Project, a dataset was established comprising water chemistry, three-dimensional fluorescence spectra, and stable isotopes for different water bodies. Results indicated significant differences in Electrical Conductivity (EC), Total Dissolved Solids (TDS), and Ca2+ concentration among the gushing water, river water, and the water from the Middle Route of South-to-North Water Diversion Project (MRSD). Analysis using parallel factor analysis (PARAFAC) and fluorescence index revealed that dissolved organic matter (DOM) in the MRSD mainly originated from endogenous sources, while the river water and gushing water showed influences from both endogenous and exogenous sources. Nitrate sources varied among the water bodies, with distinct contributions from domestic sewage and fertilizer sources. The evaporation lines of river water and gushing water exhibited similar intercepts and slopes, but their intercepts and slopes are much smaller than those of the MRSD, suggesting stronger kinetic evaporative fractionation. In conclusion, the gushing water in the riverine area of the MRSD was determined to originate from the river, providing a fast and efficient method for gushing water source identification.

Environmental and socioeconomic aspects related to the acceptance of direct potable reuse in a metropolitan city in Brazil

Water scarcity is a real global threat that must be tackled to ensure biodiversity conservation, human welfare and development, and sustainability. Direct potable reuse (DPR) has been considered a promising strategy to guarantee public supply in regions with severe problems with water scarcity and high-water demand. The success of reuse practices mainly depends on the triad technology, regulation, and public acceptance. This study investigated public acceptance as a technical parameter to assess the implementation feasibility of DPR in large cities of developing countries. Residents of Campinas City (São Paulo, Brazil) were consulted through a multiple-response questionnaire addressing sociodemographic aspects, personal environmental perceptions, and the acceptable uses for wastewater reuse. The results showed a low rejection rate (∼7%) to DPR despite this not being regulated in Brazil. A total of 47% of the volunteers declared that they would accept the DPR of domestic sewage after appropriate treatments and technologies approved by the World Health Organization (WHO), and 46% would accept it after more information. Age was an essential factor for DPR acceptance, being greater among those between 30 and 45 years old. No statistically significant differences in potable reuse acceptability were observed among participants' sex and self-declaration of race. The majority of volunteers (85%) considered water reuse very important, and most participants (51%) already practice non-potable household water reuse daily and do so out of environmental awareness. Trust in the water supply concessionaire was a key factor in DPR acceptance. This study is essential for discussing innovative public-oriented solutions to achieve water security in developing countries, especially considering the scarcity of investigations on DPR acceptability in South America.

Spatial and temporal characteristics of non-point source pollution and risks in the drinking water source area: A case study of Heihe River in Xi’an

Climate change and human activities have posed challenges to the availability and quality of drinking water resources. In water-stressed regions of northern China, pollution in water source areas has significantly impacted public health and hindered socio-economic development. This study focuses on an important water source area in Xi’an city and utilizes high-resolution multi-source integrated remote sensing images from Google Earth and Sentinel-2 remote sensing data to interpret land use information in the water source area. The Analytic Hierarchy Process (AHP) and Non-Point Source Pollution Risks Index (NPPRI) method were employed to assess non-point source pollution risks and analyze their spatial distribution characteristics. Additionally, water quality data from 2011 to 2021 in the water source area were combined to analyze the impact of land use changes on water quality. The results indicate that most water quality indicators meet Class II standards, with total nitrogen being the main pollutant exceeding the standards, primarily originating from non-point sources such as domestic sewage, livestock, and agricultural fields within the region. The overall non-point source risk within the water source area is relatively low. The NPPRI is influenced by three factors: the proportion of non-point source risk areas within the first-level protection zone, the second-level protection zone, and the small watershed. High-risk level small watersheds are the main areas affected by non-point source pollution and should be given priority in management efforts. Therefore, based on the spatial distribution of risk factors, regional pollution prevention and control measures should be implemented to mitigate water source risks and ensure drinking water security. The research findings can provide data support for the refined management of water source area risks.

Comparison and analysis of discharge standards of rural domestic sewage in different regions

China rural habitat remediation work has made significant progress. As part of this effort, various regions have implemented rural sewage treatment pollutant discharge standards, taking into account their unique economic foundations, management levels, and characteristics of rural sewage discharge. A comparative analysis of the rural domestic sewage discharge standards in the southeastern and northwestern regions of China reveals that these standards primarily consider the water environment quality of the receiving water bodies. However, there are substantial variations in pollutant concentration limits for rural sewage discharged in different regions. This research aims to guide the transition of rural sewage treatment from high-standard discharge to resource utilization. Additionally, it seeks to provide valuable insights for the selection of sewage treatment technologies, models, and governance strategies in different regions of China.

Rural integrated sanitation assessment at community level in Chongqing, China—A cluster analysis

Equitable access to sanitation for all is a goal of sustainable development, notably in rural areas. However, studies including economic, socio-cultural, and other factors that have been conducted to comprehensively assess rural sanitation at the community level in developing countries are limited. This study aimed to investigate the current state of rural environmental sanitation on the community level and to evaluate the characteristics of the diverse sub-clusters. A multidimensional environmental sanitation survey was conducted on 400 communities in Chongqing, China in 2020, and the priority options for improving sub-clusters’ sanitation were explored using cluster analysis. Among all communities, more than 60 % had positive village appearance, 50.50 % had domestic sewage treatment, and the coverage rate of household sanitary toilets was 72.28 %. The average content for lead, cadmium (Cd), and chromium in soil was 26.01, 0.53, and 54.47 mg/kg, respectively. The communities were clustered into 3 groups (I, II, III) based on similar characteristics including basic information, village appearance, water, sanitation, hygiene management, bio-vector control, and soil pollution. The proportion of cluster I, II, and III was 39.25 % (157/400), 31.75 % (127/400), and 29.00 % (116/400), respectively. Each cluster had its sanitation characteristics, and significant differences among the sub-clusters were observed in Cd of soil (p = 0.001), domestic sewage disposal ratio (p < 0.001), and environmental health funding (p = 0.001). To sum up, the environmental sanitation in rural areas of Chongqing was better than that of the national average in China, but the Cd content of farmland soil was higher. Our study provides novel evidence for assessing the characteristics of rural sanitation at the community level, and communities with similar environmental health status were clustered into the same group, while the heterogeneity of different sub-cluster was thoroughly characterized. The hierarchical control strategy should be performed in communities based on different characteristics and deficiencies of the clusters to improve environmental sanitation.

Partial nitrification and simultaneous denitrification in sequential anaerobic and aerobic reactors: performance and microbial community dynamics

ABSTRACT The removal of organic matter and nitrogen from domestic sewage was evaluated using a system composed of two sequential reactors: an anaerobic reactor (ANR) with suspended sludge and an aerobic (AER) reactor with suspended and adhered sludge to polyurethane foams. Nitrogen removal consisted of AER operating at low dissolved oxygen (DO) concentrations; this favoured the simultaneous nitrification and denitrification (SND) process. The concentration of COD and N were 440 mgO2.L−1 and 37 mgTN.L−1, respectively. The operation was divided into three phases (P), lasting 51, 53, and 46 days, respectively. The initial DO concentrations applied in the AER were: 3.0 (PI) and 1.5 mg.L−1 (PII and PIII). In PIII, the AER effluent was recirculated to the ANR at a ratio of 0.25. Kinetic assays were performed to determine the nitrification and denitrification rates of the biomasses (ANR and AER in PIII). Changes in the microbial community were evaluated throughout phases PI to PIII by massive sequencing. In PIII, the best results obtained for chemical oxygen demand (COD) and total nitrogen (TN-N) removal efficiencies, were close to 94% and 65%, respectively. Under these conditions, system effluent concentrations below 30 mg COD.L−1 and 15 mg TN-N.L−1 were verified. The nitritation and nitration rates were 10.5 and 6.5 mg N.g VSS−1.h−1, while the denitrification via nitrite and nitrate were 6.8 and 5.8 mg N.g VSS−1.h−1, respectively. A mixotrophic community was prevalent, with Rhodococcus, Nitrosomonas, Pseudomnas, and Porphyromonas being dominant or co-dominant in most of the samples, confirming the SND process in the AER sludge.

Enhanced performance and mechanism of adsorption pretreatment for alleviating membrane fouling in AGMBR: Impact of structural variations in carbon adsorbents

The structural variances of adsorbents play a crucial role in determining the number of effective adsorption sites and pretreatment performance. However, there is still a gap in comprehending the impact of different carbon structural adsorbents on membrane fouling. Therefore, this study aimed to compare the efficacy of granular activated carbon (GAC), powdered activated carbon (PAC), and activated carbon fiber (ACF) in mitigating membrane fouling during municipal sewage reclamation using an aerobic granular sludge membrane bioreactor (AGMBR). The results demonstrated that the utilization of PAC significantly enhanced the normalized flux and reduced fouling resistance in comparison to GAC and ACF systems. PAC effectively adsorbed low and medium-molecular-weight pollutants present in raw sewage, resulting in an increase in average particle size and a decrease in foulant content on the membrane surface. The Hermia model indicated that adsorption pretreatment minimized standard blocking while promoting the formation of a sparse and porous cake layer. Moreover, according to the extended Derjaguin–Landau–Verwey–Overbeek theory, PAC has been demonstrated as the optimal antifouling system owing to its enhanced repulsion between membrane-foulant and foulant-foulant interactions. Correlation analysis revealed that the exceptional antifouling performance of the PAC system was due to its high removal rates of chemical oxygen demand (~78 %) and suspended solids (~97 %). This research offers valuable insights into the mitigation of membrane fouling through the utilization of adsorbents featuring diverse carbon structures.

Control of overflows in interception wells based on water quantity and quality in rainwater pipelines for reducing pollution to rivers

ABSTRACT The separate sewer system has led to severe river pollution because of domestic sewage infiltrations and initial rainfall pollution. Therefore, interception wells (IWs) are installed to divert sewage to the wastewater treatment plant but similarly contribute to overflow-induced river pollution on rainy days. The aim of the present study is to propose a control strategy for the regulation of IWs’ overflow based on the online monitoring data, control measures, and software simulation. The results indicate that during light rain, overflow from the IWs is minimal, requiring no control measures. However during heavy rainfall, the overflow of sewage leads to an increase in the river’s concentration of NH3-N from 0.25 to 3.04 mg/L. Finally, Simulations demonstrate a reduction in river NH3-N levels from 2.27 to 1.33 mg/L after implementation. The results indicated the substantial effectiveness of measures in mitigating the pollution originating from IWs’ overflows during rainfall events.

Investigating the Behavior and Pattern of Optimal Water Consumption in Continuous Water Distribution Networks

Due to the complexity of water distribution systems and the large scale of decision-making in their analysis, design, operation and maintenance, the need to use optimization methods in upgrading and calibrating the model has become more important than in the past. The most important issue in the simulation modeling of these systems is the consistency between the calculated and measured data. The review of records showed that in the absence of the results of unaccounted water studies in the network, the use of recommended and empirical statistical methods is still needed as one of the main elements in model calibration. The current research was carried out with the aim of improving calibration methods, investigating the effects of different patterns of unaccounted water based on the calculated water consumption pattern and determining the optimal pattern of unaccounted water within the scope of the water distribution network covered by the number of 6 ground reservoirs. Due to the fact that the exact determination of unaccounted water was not available, and on the other hand, the model calibration was affected by the amount and behavior of unaccounted water, so the difference in water production and all measured uses was considered as unaccounted water and its different behaviors in the network, it was investigated according to the behavior (pattern) of water consumption. 3 different hypotheses were evaluated based on the behavior of the network (reservoir output flow rate in the hydraulic model) with the actual behavior of the reservoir output (according to the data and statistics of the tank output meter). The comparison of three statistical and graphic parameters of pressure distribution showed that the use of the inverse model option of the customers' consumption was not considered as a water model, for calibrating the hydraulic model of the distribution network, more acceptable limits for the closeness of the predicted values to the recorded values of the hourly output reservoirs provided. The confirmation of the hypothesis of the model according to consumption as the pattern of unaccounted water for the studied network indicated that the amount of unaccounted water (unlicensed and unregistered consumers) changed along with the amount of consumption. The present research-applied method in obtaining the results can be a very effective help in designing and optimizing distribution networks for urban water and sewage management organizations (especially in big cities).

Enhanced Simultaneous Nitrogen and Phosphorus Removal in a Continuous-Flow Granular Sludge System under Gradient-Controlled Hydraulic Loading

The feasibility of the aerobic granulation of activated sludge was investigated in a continuous-flow anaerobic–anoxic–oxic system under gradient-controlled hydraulic loading on the surface of a cyclone separator. Concentrated domestic sewage was used. After 80 days of operation, 80% of activated sludge in the system was in the form of granular sludge with an average particle size of 373 μm. High removal efficiency was achieved for chemical oxygen demand (94.40%), NH4+-N (99.93%), total nitrogen (89.44%), and total phosphorus (96.92%). A batch study revealed that Pseudomonas (1.34%) and Dechloromonas (1.05%) as the main denitrifying phosphorus-accumulating organisms could efficiently remove phosphorus using nitrate as an electron acceptor, which improved the utilization efficiency of carbon sources and achieved simultaneous denitrification and phosphorus removal. Overall, the study demonstrates the feasibility of enhanced denitrification and phosphorus removal in a continuous-flow granular sludge system. The sludge system enables simultaneous nitrogen and phosphorus removal under low carbon-to-nitrogen ratios.

Cold-chain free nucleic acid preservation using porous super-absorbent polymer (PSAP) beads to facilitate wastewater surveillance

The instability of viral targets including SARS-CoV-2 in sewage is an important challenge in wastewater monitoring projects. The unrecognized interruptions in the ‘cold-chain’ transport from the sample collection to RNA quantification in the laboratory may undermine the accurate quantification of the virus. In this study, bovine serum albumin (BSA)-modified porous superabsorbent polymer (PSAP) beads were applied to absorb raw sewage samples as a simple method for viral RNA preservation. The preservation efficiency for SARS-CoV-2 and pepper mild mottle virus (PMMoV) RNA were examined during storage for 14 days at 4 °C or room temperature against the control (no beads applied). While a non-significant difference was observed at 4 °C (∼80 % retention for both control and PSAP-treated sewage), the reduction of SARS-CoV-2 RNA concentrations was significantly lower in sewage retrieved from PSAP beads (25–40 % reduction) compared to control (>60 % reduction) at room temperature. On the other hand, the recovery of PMMoV, known for its high persistence in raw sewage, from PSAP beads or controls were consistently above 85 %, regardless of the storage temperature. Our results demonstrate the applicability of PSAP beads to wastewater-based epidemiology (WBE) projects for preservation of SARS-CoV-2 RNA in sewage, especially in remote settings with no refrigeration capabilities.