Sewage Treatment Research Articles

Wastewater discharges and urban land cover dominate urban hydrology signals across England and Wales

Abstract Urbanisation is an important driver of changes in streamflow. These changes are not uniform across catchments due to the diverse nature of water sources, storage, and pathways in urban river systems. While land cover data are typically used in urban hydrology analyses, other characteristics of urban systems (such as water management practices) are poorly quantified which means that urbanisation impacts on streamflow are often difficult to detect and quantify. Here, we assess urban impacts on streamflow dynamics for 711 catchments across England and Wales. We use the CAMELS-GB dataset, which is a large-sample hydrology dataset containing hydro-meteorological timeseries and catchment attributes characterising climate, geology, water management practices and land cover. We quantify urban impacts on a wide range of streamflow dynamics (flow magnitudes, variability, frequency, and duration) using random forest models. We demonstrate that wastewater discharges from sewage treatment plants and urban land cover dominate urban hydrology signals across England and Wales. Wastewater discharges increase low flows and reduce flashiness in urban catchments. In contrast, urban land cover increases flashiness and frequency of medium and high flow events. We highlight the need to move beyond land cover metrics and include other features of urban river systems in hydrological analyses to quantify current and future drivers of urban streamflow.

MiDAS 5: Global diversity of bacteria and archaea in anaerobic digesters.

Anaerobic digestion of organic waste into methane and carbon dioxide (biogas) is carried out by complex microbial communities. Here, we use full-length 16S rRNA gene sequencing of 285 full-scale anaerobic digesters (ADs) to expand our knowledge about diversity and function of the bacteria and archaea in ADs worldwide. The sequences are processed into full-length 16S rRNA amplicon sequence variants (FL-ASVs) and are used to expand the MiDAS 4 database for bacteria and archaea in wastewater treatment systems, creating MiDAS 5. The expansion of the MiDAS database increases the coverage for bacteria and archaea in ADs worldwide, leading to improved genus- and species-level classification. Using MiDAS 5, we carry out an amplicon-based, global-scale microbial community profiling of the sampled ADs using three common sets of primers targeting different regions of the 16S rRNA gene in bacteria and/or archaea. We reveal how environmental conditions and biogeography shape the AD microbiota. We also identify core and conditionally rare or abundant taxa, encompassing 692 genera and 1013 species. These represent 84-99% and 18-61% of the accumulated read abundance, respectively, across samples depending on the amplicon primers used. Finally, we examine the global diversity of functional groups with known importance for the anaerobic digestion process.

Imidacloprid removal by modified graphitic biochar with Fe/Zn bimetallic oxides

Coping with the critical challenge of imidacloprid (IMI) contamination in sewage treatment and farmland drainage purification, this study presents a pioneering development of an advanced modified graphitic white melon seed shells biochar (Fe/Zn@WBC). The Fe/Zn@WBC demonstrates a substantial enhancement in adsorption efficiency for IMI, achieving a remarkable removal rate of 87.69% within 30 min and a significantly higher initial adsorption rate parameter h = 4.176 mg g−1·min−1. This significant improvement outperforms WBC (12.22%, h = 0.115 mg g−1·min−1) and highlights the influence of optimized adsorption conditions at 900 °C and the graphitization degree resulting from Fe/Zn bimetallic oxide modification. Characterization analysis and batch sorption experiments including kinetics, isotherms, thermodynamics and pH factors illustrate that chemical adsorption is the main type of adsorption mechanism responsible for this superior ability to remove IMI through pore filling, hydrogen bonding, hydrophobic interaction, electrostatics interaction, π-π interactions as well as complexation processes. Furthermore, we demonstrate exceptional stability of Fe/Zn@WBC across a broad pH range (pH = 3–11), co-existing ions presence along with humic acid under various real water conditions while maintaining high removal efficiency. This study presents an advanced biochar adsorbent, Fe/Zn@WBC, with efficient adsorption capacity and easy preparation. Through three regeneration cycles via pyrolysis method, it demonstrates excellent pyrolysis regeneration capabilities with an average removal efficiency of 92.02%. The magnetic properties enable rapid separation facilitated by magnetic analysis. By elucidating the efficacy and mechanistic foundations of Fe/Zn@WBC, this research significantly contributes to the field of environmental remediation by providing a scalable solution for IMI removal and enhancing scientific understanding of bimetallic oxides-hydrophilic organic pollutant interactions.

Nitrogen cycling and resource recovery from aquaculture wastewater treatment systems: a review

Nitrogen cycling and resource recovery from aquaculture wastewater treatment systems: a review

Possibility and Prospects for Using Combined Coagulants-flocculants in the Urban Wastewater Treatment System

A method is proposed for producing a powdered combined reagent, including an aluminum-silicon coagulant-flocculant, a sorption material and an acidity regulator of treated wastewater, as well as using this reagent in the treatment system of multi-component urban wastewater treatment plants. It has been shown that the use of powdered reagents of various compositions ensures purification efficiency for suspended solids in the range from 66.1 to 94.1 %, and for COD – from 70.1 to 78.0 %.

Investigation of the adsorption performance and mechanism of multi-source mineral composite calcination materials on heavy metal ions

To address the challenges of plume generation and the release of heavy metal ions caused by deep-sea mining operations, this study utilized multi-source minerals, including steel slag (SS), oceanic manganese nodules (OMN), attapulgite (AT), and sawdust (SD), to fabricate a multi-source mineral composite calcination material (MMCCM) through a sintering process, and then the preliminary heavy metal ion adsorption experiment was carried out. The results indicated that both Langmuir and Freundlich models can describe the adsorption behavior of Cu2+ in a single system, while the Freundlich model was more applicable in competitive systems. The adsorption of Co2+ and Ni2+ consistently aligned with the Langmuir model across all systems. The adsorptive behavior conformed to pseudo-second-order kinetics, indicating that chemisorption played a leading role. The intraparticle diffusion was the principal rate-limiting step, and the adsorption process was spontaneous. BET, TG-DTG, SEM-EDS, XRD, FT-IR and XPS elucidated that surface physical adsorption, ion exchange, complexation with functional groups, electrostatic attraction, and co-precipitation, which were the predominant adsorption mechanisms for MMCCM. Evaluations of regenerability, economy, security, and suitability demonstrated that MMCCM is an eco-friendly adsorbent, which provides materials and data support for future heavy metal marine sewage treatment, especially for immobilizing heavy metal in deep-sea sediments.

Unraveling the Pollution and Discharge of Aminophenyl Sulfone Compounds, Sulfonamide Antibiotics, and Their Acetylation Products in Municipal Wastewater Treatment Plants.

Aminophenyl sulfone compounds (ASCs) are widely used in various fields, such as the pharmaceutical and textile industries. ASCs and their primary acetylation products are inevitably discharged into the environment. However, the high toxicity of ASCs could be released from the deacetylation of acetylation products. Still, the occurrence and ecological risks of ASCs and their acetylation products remain largely unknown. Here, we integrated all of the existing ASCs based on the core structure, together with their potential acetylation products, to establish a database covering 1105 compounds. By combining the database with R programming, 45 ASCs, sulfonamides, and their acetylation products were identified in the influent and effluent of 19 municipal wastewater treatment plants in 4 cities of China. 13 of them were detected for the first time in the aquatic environment, and 12 acetylation products were newly identified. The cumulative concentrations of 45 compounds in the influent and effluent were in the range of 231-9.96 × 103 and 26-2.70 × 103 ng/L, respectively. The proportion of the unrecognized compounds accounted for 60.6% of the influent and 62.8% of the effluent. Furthermore, nearly half of the ASCs (46.7%), other sulfonamides (49.9%), and their acetylation products (46.2%) were discharged from the effluent, posing a low-to-medium risk to aquatic organisms. The results provide a guideline for future monitoring programs, particularly for sulfadiazine and dronedarone, and emphasize that the ecological risk of ASCs, sulfonamides, and their acetylation products needs to be considered in the aquatic environment.

A Strategic Approach to Sustainable Wastewater Management and Reuse in Saudi Arabia

A Strategic Approach to Sustainable Wastewater Management and Reuse in Saudi Arabia

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.

Evaluation of River and Groundwater Quality in the Mzimvubu to Tsitsikamma Water Management Area (WMA7)

This paper assessed and evaluated the river and groundwater quality of five major catchments in the Mzimvubu to Tsitsikamma Water Management Area (WMA7). The river assessment and evaluation considered the present state maximum, minimum and mean seasonal values of physiochemical parameters (EC, NO3 + NO2, Cl, pH, NH4-N, PO4-P and Mg). The study was able to successfully make use of statistical analysis and a water quality index in order to explain seven-year trends and the present state of all five catchments within the study area. The statistical analysis results showed that water quality parameters such as PO4, NH4 and NO3 + NO2 were not complying with the South African Water Quality Guidelines (SAWQG) limits, suggesting that the study area was impacted by anthropogenic activities such as agriculture, sewage works, etc. The application of WQI showed that the Gamtoos catchment was in a good water quality state (49.71) while the other four catchments were in a poor to very poor state, according to the WQI classification. Based on the groundwater quality assessment, the physicochemical parameters (NH4, EC, Ca, NO3 + NO2, pH, Na, Cl, Mg, F, K, SO4 and CaCO3) were selected and the main parameters of concern were EC (salinity), NO3 + NO2 and SO4. However, groundwater assessment revealed that groundwater quality was chemically suitable for drinking purposes in most parts of the study area. Therefore, the study recommended resource-directed measures to improve surface and groundwater resource protection, especially in areas where surface and groundwater quality for other uses remains a challenge. Further, strong water resource compliance monitoring and enforcement to control water resource pollution sources is critical.

Striking a Balance: Decentralized and Centralized Wastewater Treatment Systems for Advancing Sustainable Development Goal 6

Water scarcity and sanitation pose a critical global challenge worsened by population growth and the finite nature of freshwater resources. Despite the United Nations’ Sustainable Development Goal 6 (SDG6) advocating for universal water and sanitation access, progress remains insufficient. Presently, approximately 50% of generated wastewater is released into the environment without adequate treatment, emphasizing the urgent need to address this issue. This article examines the socio‐economic and technical aspects of both centralized and decentralized wastewater treatment systems (DWTS) and assesses the environmental impact, spatial footprint, and energy usage across treatment technologies. An economic analysis underscores the cost advantages of DWTS, especially in sparsely populated regions. With modular designs, DWTS not only provides environmental and economic advantages but also enables water reuse. The research concludes that adopting DWTS is crucial in achieving SDG6 targets and ensuring universal access to safe sanitation, especially in low‐density and newly developed areas. This thorough investigation of wastewater management contributes to the ongoing dialogue on sustainable solutions amidst escalating global challenges of water scarcity and sanitation.

Advanced Technology for Energy, Plant Nutrients and Water Recovery at Wastewater Treatment Plants

In present times, with increasing emphasis on circular economies, municipal wastewater treatment plants (WWTPs) are considered resource recovery facilities. The targeted resources are water, biogas, and sludge, organic residuals containing nutrients and elements needed by plants (nitrogen and phosphorus). Sludge is a byproduct that constitutes the largest volume of all other byproducts obtained in wastewater treatment plants. Its processing and disposal are challenging for environmental engineers because of its complexity. Thus, quick development and implementation in industrial practice of sludge valorization and utilization technologies is required, where high nutrient content must be taken into account. Also, the occurrence of a variety of pathogens in sewage sludge is a matter of concern, even in the case of developed countries. The use of untreated sludge or wastewater in agricultural activities poses a serious risk of bacterial and parasitic infection in human beings. To overcome such issues, the application of ionizing radiation processing, especially electron beam (EB), can be considered a promising method. Its effectiveness in pathogen removal has been proven by researchers. Water radiolysis products created during irradiation of water are highly reactive and cause some effects such as DNA damage, OH • radical production, etc. Additionally, ionizing radiation technologies in sewage sludge treatment enhance the efficiency of the methane fermentation process. Depending on specific needs, different types of ionizing radiation sources can be discussed. Based on the review information and our research results, the basic engineering parameters of hybrid installation have been presented as the conclusion of the report. In this technical solution, a notably effective additional step would be the use of EB irradiation, combined with conventional wastewater treatment, to achieve efficient removal of pollutants.

Efficient Nimesulide degradation via chlorination and sun-simulated radiation: Kinetic insights, reactive species formation, and application to real wastewater

Hypochlorite mediated oxidation had been established as an efficient process for degrading organic pollutants in water. In this research work, it was evaluated the synergistic potential of solar light irradiation combined with hypochlorite on a emerging contaminant model such as Nimesulide (NIM), a nonsteroidal anti-inflammatory drug. These experiments shown that at pH 3.0, where only hypochlorous acid (HOCl) prevails, the degradation constant of NIM exhibited an increase from 2.50 × 10−4 s−1 (under dark conditions) to 1.53 × 10−3 s−1 (sun-simulated radiation), signifying an approximately six-fold acceleration in degradation. Moreover, under approximately neutral pH value (7.5) wherein both HOCl and hypochlorite ion (ClO−) coexist, the enhancement observed was approximately twofold, in particular a mineralization up to 32 % was observed. This investigation also included quenching experiments conducted at varying pH levels, shedding light on the role of specific reactive species and their contributions to the degradation mechanism. The impact of synergistic effect between solar-simulated irradiation and hypochlorite systems on NIM degradation showcases a remarkable kinetic enhancement, particularly evident at lower pH values. The degradation byproducts have been identified via high resolution HPLC-MS and the main ion formed during the reaction have been monitored by IC-MS. Experiments in real sewage treatment plant waters using sun radiation revealed the promising potential and efficiency of this alternative method, despite a comparatively lower degradation rates when compared with UV lamp application. This approach offers a sustainable and economically advantageous solution for wastewater treatment.

Modified rare earth waste composite material for simultaneous denitrification and recovery of phosphate in water

Nitrogen and phosphorus discharged into water bodies with sewage are the main causes of water eutrophication.Currently,the adsorption method is a cost-effective and efficient denitrification and phosphorus removal technology. In this study, waste polishing powder, manganese dioxide and sepiolite are used as raw materials, and a novel adsorbent of Sep-pp-MnO2 is prepared through co-precipitation and redox methods for simultaneous removal of ammonia nitrogen and recovery of phosphate in water.The physicochemical properties of the adsorbent are characterised, and the adsorption performances and denitrification and phosphorus removal mechanisms are determined. Results showed that,at a temperature of 25°C and pH of 8, the maximum removal of ammonia nitrogen reaches 11.47 mg/g, while the adsorption capacity for phosphates is 14.93 mg/g. Adsorption mechanisms indicated that the removal mechanism of phosphate is ligand exchange, while the removal mechanism of ammonia nitrogen involves electrostatic attraction and oxidation to nitrogen. Recycling experiments showed that after five desorption cycles, the material could achieve a removal of 4.7 mg/g for ammonia nitrogen, an adsorption capacity of 8.25 mg/g for phosphate and a phosphate recovery rate of 55 % after desorption with 0.1 M NaOH solution. Municipal wastewater validation experiments demonstrated that when the dosage of Sep-pp-MnO2 was 4 g/L,Treated water met the Class B requirements of the comprehensive emission standard for pollutants from urban sewage treatment plants in China (GB18918–2002). This study explores a new method for efficient simultaneous nitrogen and phosphorus removal in water and provides a feasible idea for alleviating the shortage of phosphate rock resources.

Multi‐strategy Grey Wolf Optimizer for Engineering Problems and Sewage Treatment Prediction

Multi‐strategy Grey Wolf Optimizer for Engineering Problems and Sewage Treatment Prediction

Evidence of autotrophic direct electron transfer denitrification (DETD) by Thiobacillus species enriched on biocathodes during deep polishing of effluent from a municipal wastewater treatment plant

Cathodes can play a pivotal role as electron donors for denitrification in wastewater treatment plants, facilitating the removal of nitrogen-containing compounds such as nitrate. Denitrifying bacteria can either accept electrons directly from the electrode or indirectly via electron shuttling intermediaries generated at the cathode. In this study, comparative analyses were conducted between two denitrifying electrochemical reactors with biocathodes poised at different potentials, one that generated H2 through water electrolysis and one that did not (−500 mV and −800 mV vs. SHE). Nitrogen removal efficiencies were much higher in the −500 mV (vs. SHE) system, >93 % compared to only 20 %. Notably, a biofilm formed exclusively on the −500 mV (vs. SHE) cathode, predominantly composed of Thiobacillus species, with the majority most similar to Thiobacillus strain 65-29. Metatranscriptomics showed that genes from Thiobacillus strain 65-29 encoding outer surface c-type cytochrome and porin proteins that could facilitate direct electron uptake, were markedly up-regulated in the −500 mV (vs. SHE) reactor. Reduced sulfur species generated by the cathode and sulfate reducing bacteria might have also provided a source of electrons for nitrate reduction. In fact, Thiobacillus in the −500 mV (vs. SHE) system exhibited elevated expression of genes involved in thiosulfate (soxABXYZ), sulfite (soeABC), and sulfide (fccAB) oxidation. These findings offer valuable insights into the mechanisms of autotrophic denitrification by Thiobacillus in mixed culture systems and provide practical guidance for engineering applications.

Radiation impact of ashes from the combustion of bottom sediments in a municipal sewage treatment plant, Czajka, located in Warsaw, Poland

Abstract The aim of the present research was to assess the radiological importance of the fly ashes generated from the incineration of sludge from the “Czajka” sewage treatment plant located in Warsaw, Poland. The γ-spectrometry technique was employed for their radiometry. The high purity germanium (HPGe) detector was mathematically energy-efficiency calibrated. The ash samples were measured two times, i.e., after 24 days and after 3 months of storage. Storage was supposed to provide a radioactive equilibrium. Radionuclides from three natural decay series, i.e., uranium–radium, uranium–actinium, and thorium, were detected in the ash samples. Apart from these, 40K, 137Cs, and 7Be were also detected. The indicated levels of radionuclides do not produce radioactive hazards, regardless of the method used for further management.

Exploring diclofenac potassium adsorption on activated carbon: A comprehensive statistical physics and experimental approach

This study aims to contribute to understanding the removal processes of diclofenac potassium (DP) medicine in wastewater treatment systems, employing activated carbon (AC) as an adsorbent. To achieve this goal, a multidisciplinary approach was adopted, integrating experimental and theoretical analyses of equilibrium data regarding the adsorption of DP on AC. Five statistical physics models were applied to determine the model best for the adsorption process. The selection of the most appropriate model considered both the performance of the models and the analysis of the estimated parameters. Statistically, all models exhibited satisfactory results. However, when analyzing the estimated parameters, the double-layer model with single adsorption energy emerged as the most suitable model to describe the analyzed process. Based on the chosen model’s parameters, we observed that as the temperature increases, the number of active sites occupied during adsorption and their availability on the adsorbent also increases. However, the number of available adsorption sites decreases as the temperature rises. The half-saturation concentration, in turn, increases with increasing temperature, suggesting that the process is favored when temperatures above room temperature are used. Additionally, higher temperatures provide better removal results, indicating that DP molecules’ non-parallel and parallel orientations on the AC surface favor the adsorption process. Finally, our combined results led to the proposal of a mechanism for DP adsorption on AC, which is based on physical adsorption interactions between adsorbate-adsorbent and adsorbate–adsorbate.

Growth, gas exchange, and leaf anatomy of Echinodorus grandiflorus (Cham. & Schltr.) Micheli under Pb contamination.

Lead (Pb) can be deposited in aquatic environments that are especially subject to pollution due to wastewater and sewage disposal. This study aimed to evaluate the tolerance of Echinodorus grandiflorus (Cham. & Schltr.) Micheli to Pb and changes in growth, gas exchange, and leaf anatomy. Experiments were conducted with E. grandiflorus plants exposed to the following Pb concentrations in nutrient solution: [0; 0.75; 1.5; 3.0 and 9.0μM Pb (NO 3)2] in a greenhouse for 60days. At the end of the experiment, the lead concentration, growth, leaf gas exchange, and changes in leaf anatomy were evaluated. There was no mortality of E. grandiflorus plants, and they accumulated higher concentrations of Pb proportional to the concentration of the pollutant in the solution. Pb did not cause significant changes in growth, stomatal conductance, transpiration, and Ci/Ca rate but reduced the photosynthesis in E. grandiflorus. The leaf anatomy showed significant changes in the presence of Pb, reducing the epidermis and chlorophyll parenchyma. E. grandiflorus demonstrated tolerance to Pb, surviving and growing under contamination; however, it negatively modified its leaf anatomy and photosynthesis in the presence of the metal.

Oxygen-doped defects modified C3N5 in enhanced molecule oxygen photoactivation for tetracycline hydrochloride degradation and H2O2 in situ production: Double pathways of 1O2 and O2–· high yield

The study aims to investigate the mechanism by which O-doped defect engineering in C3N5 enhances molecular oxygen photoactivation. A feasible one-step roasting method was adopted to synthesize a novel C3N5 with multiple O-doped defects sites (O-C3N5). The experimental characterizations and DFT analysis reveal that O atoms were doped into the in-plane structure of C3N5 to form O-doped defects located at both linked and terminal positions on triazine units. The O-doped defects transform C3N5 morphologies and diminish the band gap, favoring charge migration and electron accumulation under visible-light irradiation. Furthermore, O-doped defects improve the adsorption performance for molecular oxygen, which provides the prerequisite for photoactivating molecular oxygen. The prominent photoelectric property can high effectively photoactivate the adsorbed O2 to directly generate 1O2 in the energy transfer-mediated pathway and O2–· in the electron oxygen reduction reaction pathway. In addition, the well photoelectric property also facilitates the interconversion between 1O2 and O2–·, which enables diverse reaction applications to be achieved. Hence, the outstanding performance of O-C3N5 can be verified in photoactivating molecular oxygen for TC degradation and H2O2 in situ production. The results not only demonstrate the universality and feasibility of utilizing O-C3N5 photoactivating molecular oxygen for the advanced treatment of the complicated sewage, but also provide a comprehensive understanding on the enhanced molecule oxygen photoactivation of C3N5 through O-doped defects.