Sewage Treatment Research Articles

Microplastic Contamination in Landfill Leachate and Surface Water: Assessment of Wastewater Treatment Efficiency at the Nonthaburi Waste Management Center, Thailand

Microplastics (MPs), plastic particles smaller than 5 mm, have emerged as a significant environmental concern, particularly as contaminants originating from landfills. Landfills can serve as a major source of MPs, potentially releasing them into surface water through leachate. This study aims to investigate the contamination of MPs in leachate and surface water, as well as to evaluate the efficiency of landfill wastewater treatment in removing these particles. The research was conducted at the Waste Management Center of the Nonthaburi Provincial Administrative Organization, Thailand, with samples collected in June 2023. Sampling included two leachate sources, influent and effluent from the treatment system and surface water. The abundance and characteristics of MPs in each sample were analyzed. Results indicated a significant presence of MPs in leachate, with an average concentration of 173.98 pieces/L, while concentrations in influent, effluent and surface water were 38.40 pieces/L, 10.80 pieces/L and 11.33 pieces/L, respectively. MPs in all samples were predominantly in the size range of 16-100 µm, corresponding to 71.28-93.75% of the total particles. Polypropylene was the dominant polymer in leachate (69.66%) and effluent (48.94%), whereas acrylate copolymer (96.53%) and polytetrafluoroethylene (44.12%) were the major types found in influent and surface water, respectively. The wastewater treatment system of the landfill demonstrated an overall removal efficiency of 71.88% for MPs in leachate. These findings highlight the extent of MP contamination in landfill environments and the importance of improving treatment processes to mitigate their release into surrounding ecosystems.

Evaluation of the effect of disposal of landfill leachate in a sewage treatment plant composed of stabilization ponds

This study aimed to evaluate the combined treatment system of domestic sewage and leachate by serial stabilization ponds in a Wastewater Treatment Plant (WWTP). The WWTP had two parallel pond modules, one receiving (module II—pond M10) and the other not receiving leachate (module I—pond M5). Physical, chemical, and biological monitoring parameters collected from January 2017 to December 2021 were evaluated. High reducing efficiency for ammonium nitrogen was found, with an average of 95.7 ± 2.5%. BOD5 and COD can be considered statistically different for a 95% confidence level in the two pond modules. The phytoplankton community was composed of 46 taxa distributed in four taxonomic classes: 6 belonging to the Cyanobacteria group (13%), 22 to the Green Algae group (48%), 4 to the Diatoms group (9%), and 14 to the Phytoflagellate group (30%). No ecotoxicity was detected for the evaluated pond effluent samples. Thus, although the insertion of leachate impacted the quality of the final effluent of the ponds and the organic matter, it may not have affected the effluents’ ecotoxicity. This research helps to understand the impacts of long-term leachate insertion in a real treatment system using stabilization ponds for combined treatment. In addition to the usual efficiency evaluation parameters, ecotoxicological tests and phytoplankton are also evaluated.

Ultrasound-Assisted Community Bureau of Reference (BCR) Procedure for Heavy Metal Removal in Sewage Sludge

Sewage sludge (SS) resulting from wastewater treatment plants (WWTP) is commonly applied worldwide as a fertilizer in agriculture. This can be done following a rigorous analysis of the sewage sludge composition. Due to its toxic potential, heavy metal ion content is one of the key parameters to test when evaluating SS sample usage as fertilizer. The distribution of metals present in SS samples produced by five municipal WWTPs in Romania was studied. To obtain information regarding metal distribution in SS, a modified ultrasound-assisted extraction procedure of the Community Bureau of Reference (BCR) was employed for As, Cd, Cr, Cu, Mo, Ni, Pb, Zn, and Co quantitation. Concentrations of these metals were measured using ICP-EOS spectrometry. Method extraction accuracy was verified using CRM-483 certified reference material. Results show that extraction efficiency was lowest for the exchangeable fraction for all studied metals. The detected ion metals were found distributed in fractions (F) 2 and 3, which are unavailable for plants and groundwater under natural environmental conditions. One noteworthy finding was that using ultrapure water for the leachate test resulted in low metal solubility, indicating slight metal desorption in real environmental samples. Furthermore, maize stalk bio-adsorbent was used to minimize metal ion content in WWTP leachate samples produced by the storage of SS in terms of metal ion adsorption.

Study on Operation Effect of Two-Stage MSL System for Rural Decentralized Sewage Treatment

To improve the removal efficiency of rural domestic sewage, a two-stage multi-soil-layer sewage treatment system with an “aeration section + non-aeration section” was designed, and its treatment performance was observed under different influent loads and aeration intensities. The experiment ran for a total of 150 days, and the results showed that the two-stage multi-soil-layer (MSL) system could effectively reduce the effluent concentration of sewage to meet discharge standards. Under the operating conditions of an influent hydraulic load of 1000 L·m−2·d−1 and an air–water ratio of 4:1, the final effluent average concentrations of COD, NH3-N, TN, and TP were 106.5 mg·L−1, 7.4 mg·L−1, 13.9 mg·L−1, 0.12 mg·L−1, and 18.6 mg·L−1, respectively, with average removal rates of 85.3%, 82%, 72.5%, 96%, and 85%. A longer hydraulic retention time and ideal anoxic conditions were ensured by designing a certain effluent height in the system. Adding aeration to the system allowed for a synchronous nitrification–denitrification reaction under reasonable influent loads, ultimately enabling the effluent to meet discharge standards.

Optimization of sewage treatment processes: Process control based on artificial intelligence

Abstract. The optimization of sewage treatment processes is critical for improving efficiency and reducing energy consumption. This paper explores the application of machine learning and artificial intelligence algorithms in optimizing key processes such as aeration, sedimentation, and filtration. By leveraging real-time monitoring and adaptive control, these algorithms can dynamically adjust operational parameters to enhance treatment efficiency and minimize energy usage. This study provides detailed insights into the implementation and benefits of AI-driven process control in sewage treatment, supported by case studies and data analysis. The findings indicate significant improvements in treatment performance, showcasing the transformative potential of AI in environmental engineering.

Customized Measurable Availability Framework of Sewage Treatment Plant Through Risk Priority Number

Customized Measurable Availability Framework of Sewage Treatment Plant Through Risk Priority Number

Electrocoagulation as a Remedial Approach for Phosphorus Removal from Onsite Wastewater: A Review

Onsite wastewater treatment systems (OWTSs), although essential for managing domestic sewage in areas without centralized sewerage treatment plants, often release phosphorus (P) into the environment due to inadequate treatment. This unregulated P discharge exacerbates water quality degradation and jeopardizes aquatic habitats and human health. Among different treatment technologies, electrocoagulation (EC) demonstrates considerable potential for addressing this challenge by efficiently removing P from OWTSs and thus protecting water resources and ecological integrity. Through electrochemical reactions, EC destabilizes and aggregates P-bearing particles, facilitating their removal through precipitation. Compared to conventional treatment approaches, i.e., chemical and biological methods, EC offers several advantages, including high efficiency, minimal chemical usage, and adaptability to varying wastewater compositions. This review underscores the urgent need for mitigating P discharge from OWTSs and the efficacy of EC as a sustainable solution for P removal, offering insights into its mechanisms, reactor design considerations, important operational factors, performance, and potential applications in OWTSs as well as providing future research directions.

Acid mine drainage bioremediation using bacteria enriched from the confluence zone between its flow and treated sewage

AbstractSediments from the confluence zone between an acid mine drainage stream and a water stream receiving the effluent from a municipal wastewater treatment plant were inoculated in a Postgate B medium base having methanol, glycerol, or ethanol as carbon source/electron donor, over a pH range between 2.00 and 6.00, aiming to obtain native cultures enriched in acidophilic/acid-tolerant sulfate-reducing bacteria. The most effective sulfate reduction observed in acidic conditions was in the enrichment cultures with methanol. Thus, the microbial consortium enriched in these conditions was further used in acid mine drainage bioremediation experiments at an initial pH of 4.50 and using different doses of nutrients medium base and methanol as carbon source/electron donor. The most promising results, with more than 99% removal of metals, were obtained in the mixture of 20% Postgate B medium base plus 80% acid mine drainage (v/v), which corresponds to 0.115% basal salts and 0.02% yeast extract (w/v). Metataxonomic analysis based on 16S rRNA gene sequences showed the presence of Desulfosporosinus spp. in all enrichment cultures, with the highest relative abundance in cultures at pH 4.00 with methanol. Furthermore, metataxonomic analysis in the acid mine drainage remediation tests revealed the presence of Desulfosporosinus spp. in all tested conditions. In addition, the study also revealed Clostridium members in all tests. Plus, their relative abundances were related to the dose of nutrient medium base and in balance with the abundances of Desulfosporosinus spp.

Profiling the bacterial microbiome diversity and assessing the potential to detect antimicrobial resistance bacteria in wastewater in Kimberley, South Africa

Wastewater treatment plants (WWTPs) are hotspots for pathogens, and can facilitate horizontal gene transfer, potentially releasing harmful genetic material and antimicrobial resistance genes into the environment. Little information exists on the composition and behavior of microbes in WWTPs, especially in developing countries. This study used environmental DNA (eDNA) techniques to examine the microbiome load of wastewater from WWTPs. The DNA was isolated from wastewater samples collected from the treatment trains of three WWTPs in Kimberley, South Africa, and the microbial diversity and composition was compared through 16 S rRNA gene sequencing. The microbes detected were of the Kingdom Bacteria, and of these, 48.27% were successfully identified to genus level. The majority of reads from the combined bacterial data fall within the class Gammaproteobacteria, which is known to adversely impact ecological and human health. Arcobacteraceae constituted 19% of the bacterial reads, which is expected as this family is widespread in aquatic environments. Interestingly, the most abundant bacterial group was Bacteroides, which contain a variety of antibiotic-resistant members. Overall, various antibiotic-resistant taxa were detected in the wastewater, indicating a concerning level of antibiotic resistance within the bacterial community. Therefore, eDNA analysis can be a valuable tool in monitoring and assessing the bacterial microbiome in wastewater, thus providing important information for the optimization and improvement of wastewater treatment systems and mitigate public health risks.

Mathematical model of dissolved microbial products in sewage treatment system

Water is the source of life, but all kinds of water resources in the world are suffering from different degrees of pollution. Water pollution leads to a serious shortage of available fresh water resources, and sewage treatment is the main way to solve water pollution. For the sewage after biological treatment of activated sludge, the organic matter contained in the effluent is mainly the dissolved microbial products (SMPs) produced in the process of microbial metabolism. The composition of SMPs is complex, mainly including macromolecular substances such as protein, polysaccharide, humic acid and DNA and cell fragments. The mathematical model of activated sludge is a quantitative description of the mathematical relationship between substrate degradation parameters and microbial growth. Starting from the Monod equation representing the relationship between substrate consumption and microbial growth, it combines the reactor theory and microbiology theory in the chemical field. Based on the principle of conservation of materials and Monod equation, the mathematical expression of organic degradation model was determined according to the collected data and empirical values of parameters. The general idea of activated sludge model No.1 (ASM1) for activated sludge process simulation was introduced, and the influence of sludge concentration on SBR process water treatment was explored. It was found that the removal rate of COD, ammonia nitrogen, total nitrogen and total phosphorus increases with the increase of sludge concentration. When C/N=8, the removal rate of ammonia nitrogen increased from 62% to 81%, and the removal rate of total nitrogen increased from 64% to 82%, with the most obvious effect.

The role of information and participation in overcoming users’ initial reluctance: a case study of a decentralized wastewater treatment plant

Decentralized wastewater treatment systems are a potential solution to the water crisis. However, in addition to advanced technology, successful implementation of these systems requires broad public willingness to use them. This paper presents the results of a three-phase psychosocial intervention with the users of a business building where a decentralized wastewater treatment plant was installed. The intervention, motivated by complaints from users due to their lack of knowledge about the existence of the plant, aimed at understanding and improving users’ perceptions of the building’s decentralized system. In the first phase, we conducted a focus group with a sample of workers (n = 6) to understand their knowledge and perception of the building’s decentralized wastewater treatment system. Once the main obstacles and facilitators were identified, we designed a second phase where a group of employees (n = 46) were exposed to environmental priming to improve attitudes toward the decentralized plant installed in the building. Finally, in the third phase, a bidirectional informative session was proposed, conducted by experts, to another group of workers (n = 25). Findings suggest that implementing specific psychosocial strategies, such as promoting environmental awareness and providing informative sessions, along with incorporating potential users throughout the process, contributes to better acceptance of the decentralized wastewater treatment plant. This work presents a real case in a pilot plant that can serve as a guide for addressing psychosocial resistance in similar projects.

Enhancing Expert Decision-Making for Wastewater Treatment Plants with Seidel Laplacian Energy and Cosine Similarity Measure in Intuitionistic Fuzzy Graphs

Wastewater treatment facilities’ main goal is to protect the public and environment from the hazardous and poisonous materials found in wastewater. Water treatment facilities were developed to speed up the natural process of cleansing water. A novel cosine similarity measure across intuitionistic fuzzy graphs has been proven to be more effective than certain present ones in group decision-making issues using example verification. This paper provides a unique approach for calculating expert-certified, well-known scores by finding the ambiguous information of intuitionistic fuzzy preference relations as well as the regular cosine similarity grades from one separable intuitionistic fuzzy preference relation to another. The new technique considers both "objective" and "subjective" information provided by experts. Using intuitionistic fuzzy preference relations, we provide workable techniques for judging experts’ eligible reputational ratings. This can be used to raise or decrease the relevance of the stated criteria in an evaluation that takes into account several competing elements. We give a solution to a decisional problem by using two effective methods: the newly constructed cosine similarity measure and the Seidel Laplacian energy (SLe+) of an intuitionistic fuzzy graph. Finally, two working procedures and circumstances are offered to show the effectiveness and superiority of the proposed techniques.

Aerobic–anaerobic DHS reactor for enhancing denitrification in municipal wastewater treatment

Providing anaerobic environments can enhance the denitrification capacity of wastewater treatment systems. This study developed an aerobic–anaerobic downflow hanging sponge (DHS) reactor to increase denitrification. A siphon tube was integrated with a conventional DHS to create anaerobic conditions by controlling a water column inside the reactor. The siphon heights were set in the middle of the reactor, representing 2/5 of the total volume. Anaerobic conditions were maintained at the bottom (1/5), whereas aerobic conditions were maintained at the top (2/5). The middle part experienced alternating aerobic–anaerobic conditions within a siphon cycle. The hydraulic retention time (HRT) was 3 h, and the temperature was maintained at 30 °C. The study was divided into the low-loading and standard phases based on the influent soluble chemical oxygen demand (sCOD) concentration. During the low-loading phase, the aerobic–anaerobic DHS exhibited a higher sCOD removal rate (53.6 ± 26.6 %) than the control aerobic DHS (35.6 ± 31.9). However, the removal efficiencies for NH₄+–N and total nitrogen (TN) were lower, averaging 37.1 ± 24.7 % and 31.5 ± 21 %, respectively. In the standard phase, the aerobic–anaerobic DHS achieved an sCOD removal rate of 69.3 ± 14.8 % and an NH₄+–N removal rate of 17.2 ± 11.4 %. The control aerobic DHS showed higher sCOD and NH₄+–N removal at 84.7 ± 10.8 % and 54.1 ± 12.8 %, respectively, possibly due to the reduced aerobic zone volume in the aerobic–anaerobic DHS. The TN removal rates were also lower in the aerobic–anaerobic DHS (17.1 ± 11.4 %) than in the control DHS (25 ± 12.3 %). However, based on the ratio of nitrification to TN removal, the aerobic–anaerobic DHS showed a high denitrification rate of 85 %–100 %. The highest number of denitrifiers was in the middle section of the aerobic–anaerobic DHS, with Rhodocyclaceae the most prominent, followed by Comamonadaceae. Maintaining an anaerobic zone improved the denitrification capacity, indicating the potential of the aerobic–anaerobic DHS for efficient municipal wastewater treatment.

Toward Zero Waste: Sustainable Practices in Waste Management at ETUT

The paper discusses Oguz Han Engineering and Technology University of Turkmenistan's (ETUT) waste management initiatives, particularly its Zero Waste Program aimed at minimizing waste generation and promoting sustainability across campus. Strategies include educational campaigns, eco-friendly purchasing, and collaboration with vendors for waste reduction, reuse, and recycling. ETUT employs structured waste categorization, centralized repositories for reusable items, and a recycling plant with advanced sorting machinery. Innovative methods like paper recycling and composting are used, along with exploring plastic repurposing into fibers and fuel. Organic waste management includes composting, notably reducing landfill waste. Inorganic waste reduction involves paper recycling, plastic conversion, and electronic repair and donation. The program emphasizes waste reduction through recycling and reuse, including upcycling workshops. Hazardous waste from laboratories is managed with local authorities for safe disposal, while relevant associations for environmental safety oversee sewage disposal. These strategies highlight ETUT's commitment to sustainability, positioning it as a regional leader in responsible waste management.

Surface water quality in Costa Rica: new initiatives and challenges

ABSTRACT Despite Costa Rica's reputation for being a leader in environmental policy and its thriving nature-based tourism industry, the nation has had poor surface water quality. Reasons for poor water quality include the lack of sewerage treatment, overuse of septic tanks, and the application of large quantities of agrichemicals. Although Costa Rica has policies to maintain surface water quality, they have not been sufficiently implemented. Recent initiatives have addressed surface water quality, including an ambitious plan to expand treated sewerage systems in all urban areas. Current efforts to meet this goal have focused on the San Jose metropolitan area and coastal communities. This paper reviews the advances and challenges to Costa Rica's efforts to improve water quality.

Genomic surveillance of Canadian airport wastewater samples allows early detection of emerging SARS-CoV-2 lineages

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has shown wastewater (WW) surveillance to be an effective means of tracking the emergence of viral lineages which arrive by many routes of transmission including via transportation hubs. In the Canadian province of Ontario, numerous municipal wastewater treatment plants (WWTPs) participate in WW surveillance of infectious disease targets such as SARS-CoV-2 by qPCR and whole genome sequencing (WGS). The Greater Toronto Airports Authority (GTAA), operator of Toronto Pearson International Airport (Toronto Pearson), has been participating in WW surveillance since January 2022. As a major international airport in Canada and the largest national hub, this airport is an ideal location for tracking globally emerging SARS-CoV-2 variants of concern (VOCs). In this study, WW collected from Toronto Pearson’s two terminals and pooled aircraft sewage was processed for WGS using a tiled-amplicon approach targeting the SARS-CoV-2 virus genome. Data generated was analyzed to monitor trends of SARS-CoV-2 lineage frequencies. Initial detections of emerging lineages were compared between Toronto Pearson WW samples, municipal WW samples collected from the surrounding regions, and Ontario clinical data as published by Public Health Ontario. Results enabled the early detection of VOCs and individual mutations emerging in Ontario. On average, the emergence of novel lineages at the airport preceded clinical detections by 1–4 weeks, and up to 16 weeks in one case. This project illustrates the efficacy of WW surveillance at transitory transportation hubs and sets an example that could be applied to other viruses as part of a pandemic preparedness strategy and to provide monitoring on a mass scale.

Interactions between SDBS and Hydrilla verticillata − epiphytic biofilm in wetland receiving STPs effluents: Nutrients removal and epiphytic microbial assembly

The fate and effects of sodium dodecyl benzene sulfonate (SDBS) in sewage treatment plants (STPs) effluents on nutrients and submerged macrophytes are far from clear in wetlands. This study conducted a 24-day experiment to investigate changes in nutrients and epiphytic biofilm of Hydrilla verticillata in wetlands receiving effluents with 0.5, 2 and 5 mg L−1 SDBS. The decrease of SDBS in overlying water followed pseudo-first-order kinetic equation, with over 80 % of SDBS removal achieved. 2 and 5 mg L−1 SDBS decreased nutrient removal efficiency, induced oxidative stress response and damaged cells of H. verticillata. SDBS altered bacterial and eukaryotic community diversity. 0.5 mg L−1 SDBS can promote carbon fixation and methane oxidation of microorganisms. Network analysis revealed that 0.5 mg L−1 SDBS decreased the stability of epiphytic ecosystems. Mantel tests indicated significant influences of SDBS, temperature, and total nitrogen on epiphytic microbial communities.

Environmental behavior and risk of the emerging organic contaminants halogenated carbazoles in chemical industrial park clusters

Polyhalogenated carbazoles (PHCZs) are emerging organic contaminants and have attracted extensive concern because of their widespread occurrence and dioxin-like toxicity. However, the distribution characteristics, environmental behavior, and fate of PHCZs are still poorly understood. In this study, 74 composite environmental samples from 21 Chinese cities were collected around industrial parks in the Yangtze River Delta. The PHCZ concentration ranges in sediment and soil samples were 12.7–5.21 × 103 and 34.6–1.81 × 103 ng/g, respectively, which is equivalent to or higher than those of well-known persistent organic pollutants in the similar areas. The dominant congeners of PHCZs in sediment and soil were 3-chlorocarbazole and 3,6-dichlorocarbazole. Industrial emissions, especially from printing and dyeing textiles, were the main contributors to the high PHCZ environmental concentrations. Potential toxic effects of the PHCZs were evaluated using the toxic equivalent (TEQ) method. The TEQs of PHCZs in sediment and soil were up to 550 and 554 pg TEQ/g dry weight, respectively. The estimated TEQ value of sediment and soil exceeded the corresponding safety guideline, which indicated that PHCZs in the Yangtze River Delta posed high health risks. This study provides an important theoretical basis for controlling and reducing the ecological risks of PHCZs in the chemical industry. At the same time, it also provides reference for the priority control and revision of discharge standards for PHCZs in sewage treatment plants in future.

Environmental Protection for Bureaucratic Promotion: Water Quality Performance Review of Provincial Governors in China

We show including quantitative environmental targets for bureaucratic promotion incentivizes government officials to enforce environmental regulation but at significant economic costs. Taking advantage of the gradual expansion of China’s water quality performance review (WQPR) over time and space, we find that WQPR significantly reduced ambient concentrations of criteria pollutants, digestive cancer mortality, and GDP growth rate. WQPR’s effects are more pronounced along provincial borders, which are targeted by WQPR, and when provincial governors have more promotion potential. An important mechanism is investment in wastewater treatment facilities. There is evidence that WQPR passed the benefit-cost test, especially in rural areas.

The Geysers Is a Unique Geothermal Resource Presenting Equally Unique Challenges to Drillers

_ For drillers, The Geysers is a unique sort of hell. It is one of the only places on Earth where a shallow well can reach a highly fractured reservoir so hot that it only produces steam. That steam powers 18 power plants generating 835 MW of electricity, making this 45-square-mile area the world’s most prolific geothermal power producer. High drilling costs there also stand out. Drilling a well requires 60 days or so and generates a lot of damaged drill bits and drillpipe. The drilling rigs have the size and power of modern onshore rigs, but a close look reveals there’s no topdrive. Below the rig floor there is a rotary table, known as a Kelly drive because it can spin drilling pipe without being in the line of fire of the steam flowing out when running slotted casing into the steam-production zone. When they get to that zone, they switch from drilling fluid and mud to injecting a high-pressure stream of air because of the enormous fluid losses anticipated when they reach that highly fractured level. A drill bit that lasts 500 ft in this harsh, highly fractured rock has had a long run. And the rugged terrain—mountains to a Texan but hills to a Californian—makes this a hard place to move a rig. “The Geysers is its own animal, for sure,” said Sam Noynaert, a Texas A&M professor who was a key member of a team of drilling experts and scientists that drilled a well in The Geysers to test if faster drilling methods from the oil business could work there. The two upper sections went pretty well, considering. As they went deeper, they repeatedly had to deal with severe fluid losses. Still, they had shaved nearly 6 days off the average drilling time. But when they reached the highly fractured steam-producing payzone and their drilling method changed to air drilling, things got worse with drill bits failing after runs as short as 21 ft. As a Geysers drilling paper presented at the Stanford Geothermal Workshop earlier this year delicately put it: “The air section proved to be more challenging.” The Blob The Geysers has a long history. The heat source is “a large blob of silica-rich magma (which) forced its way through Earth’s crust beneath the Coast Range,” according to the description of an image from NASA. That flow about 1.3 million years ago from deep within the earth heated the overburden, making the rock brittle and prone to fracturing. Over time, water seeped into those hot fissures, creating hot springs that were awed by Native Americans and later attracted tourists to a nearby resort hotel. By the 1960s drillers were tapping the steam in those payzones for commercial power generation, which peaked at 2,000 MW in 1987. It declined from there as steam production depleted the reservoir. Eventually, the output was stabilized at its current level by injecting water from sewage-treatment plants into the production zone.