Sewage Treatment Technology Research Articles

Biochar reduces plasmid-mediated antibiotic resistance gene transfer in earthworm ecological filters for rural sewage treatment.

The spread of antibiotic resistance genes (ARGs) in rural wastewater threatens both ecological environment and human health. Earthworm ecological filters (EEFs) represent a green technology for rural sewage treatment. However, their effectiveness in removing ARGs remains a significant challenge. This study aims to investigate the role and underlying mechanisms of biochar addition in enhancing ARGs removal in rural sewage using EEFs. To achieve this, the fate of chromosome- and plasmid-carried ARGs was quantified in constructed EEFs, both with and without biochar addition. The results showed that the biochar could effectively remove ARGs from rural sewage, with a better removal efficiency for plasmid-carried ARGs. The absolute abundance of plasmid-carried ARGs in the effluent was reduced by 0.4-11 times compared to chromosomal ones, showing removal stability improved by 13.11-74.51 %. Additionally, the functional microbial community attached on the high porosity of biochar surface promoted ARGs retention, increasing diffusion limitation in microbial assembly mechanisms by 4.61-29.44 %, which played a key role in plasmid-mediated horizontal gene transfer (HGT). Partial least squares structural equation modeling (PLS-SEM) revealed that biochar-mediated environmental changes and the HGT of mobile genetic elements (MGEs) were critical factors in reducing plasmid-carried ARGs in EEFs.

A MODEL FOR SELECTION OF DECENTRALIZED SANITARY SEWER SYSTEMS FOR SMALL MUNICIPALITIES

The precariousness of sanitation services in small Brazilian municipalities is exacerbated by technical and financial limitations. In these places treatment technologies need to be simple, sustainable, economically viable, and socially accessible. This work aims to propose a selection model for decentralized sewage treatment technologies for small municipalities. The PROMETHEE II multi-criteria method was used to rank the technologies with aid decision-making agents to prioritize technical, environmental, economic, and social criteria based on the characteristics of the sewer basins. After validating the method in the sewage catchment areas of four municipalities in Paraíba, the results showed that the constructed wetlands technology occupied the best position in 88.9% of the sewer basins. This technology stands out for its high organic matter and suspended solids removal efficiency, in addition to not generating sludge and performing well in terms of social criteria (odor production and vectors). The septic tank and septic tank + anaerobic filter alternatives ranked lower in the basins studied. The robustness of the method and the assignment of preferences to criteria for sewer basins with different classifications indicate that the model is replicable for small municipalities. Thus, the study contributes to the optimization of decision-making for sewage treatment systems, allowing the better use of resources, the reduction of vulnerabilities, and promotion of municipal development.

Systematic Assessment of Practical Challenges in Rural Domestic Sewage Treatment in China: Examining Treatment Models, Ecological Risks, and Management Dilemmas

The treatment and purification of rural domestic sewage (RDS) is a pivotal focus in enhancing the living environment in rural areas. Since 2008, special funds for comprehensive rural environmental improvement have been established by the Chinese government. Numerous projects have been implemented to treat RDS, resulting in a significant enhancement of China’s rural sewage treatment ratio. However, current discussions often focus on technical investigations, process selection, and operation modes pertaining to urban sewage while overlooking the unique challenges posed by decentralized sewage treatment facilities in rural areas. This work aims to provide technical support for addressing rural sewage treatment and purification in China through an analysis of limitations associated with prevailing mainstream sewage treatment and separation technologies, ecological risks arising from new pollutants present in domestic wastewater, and subsequent management difficulties.

Theoretical insight into the removal process of isoquinoline by UV/Cl and UV/PDS: Oxidation mechanism and toxicity assessment

Isoquinoline (IQL), as a typical nitrogen-containing heterocyclic contaminant in coking wastewater, poses a serious threat to the aquatic environment and human health. Due to its chemical stability, traditional sewage treatment technology is not highly efficient in IQL removal. Advanced oxidation processes (AOPs) driven by ultraviolet radiation could be an effective treatment method, but it could generate toxic byproducts. In this work, the removal of IQL initiated by HO•, ClO•, Cl•, and SO4•- in UV/chlorine and UV/persulfate (PDS) process was comprehensively investigated, clarifying the degradation mechanism, reaction kinetics, and ecological toxicity. The findings indicate that the dominant oxidation mechanism of IQL by HO•, ClO•, and Cl• is radical adduct formation (RAF), while single electron transfer (SET) is the main reaction pathway of SO4•- with IQL. At 298 K and 1 atm, the order of rate constants for the reactions of IQL with active radicals is Cl• (6.23 × 1010 M−1 s−1) > SO4•- (8.81 × 109 M−1 s−1) > HO• (1.66 × 109 M−1 s−1) > ClO• (1.62 × 108 M−1 s−1). The acute and chronic toxicity of IQL and its degradation byproducts at three different trophic levels were evaluated using ECOSAR program. The byproducts produced by the oxidative degradation of IQL by HO• and SO4•- are mostly “not harmful”, and their toxicity shows a decreasing trend compared to that of IQL. The byproducts derived from the reaction of IQL with Cl• are all “toxic” or “harmful”, and the ranking of harm to three types of aquatic organisms is green algae > fish > daphnia. Hence, UV/PDS process could be more secure in pollutant disposal in wastewater. In actual water treatment process, merit attention should be paid to the potential hazards of the byproducts generated by various contaminants.

Shining a Light on Sewage Treatment: Building a High-Activity and Long-Lasting Photocatalytic Reactor with the Elegance of a “Kongming Lantern”

Photocatalysis is a promising technology for efficient sewage treatment, and designing a reactor with a stable loading technique is crucial for achieving long-term stability. However, there is a need to improve the current state of the art in both reactor design and loading techniques to ensure reliable and efficient performance. In this study, we propose an innovative solution by employing polydimethylsiloxane as a bonding layer on a substrate of 3D-printed polyacrylic resin. By means of mechanical extrusion, the active layer interacts with the bonding layer, ensuring a stable loading of the active layer onto the substrate. Simultaneously, 3D printing technology is utilized to construct a photocatalytic reactor resembling a “Kongming Lantern”, guaranteeing both high activity and durability. The reactor exhibited remarkable performance in degrading organic dyes and eliminating microbes and displayed a satisfactory purification effect on real water samples. Most significantly, it maintained its catalytic activity even after 50 weeks of cyclic degradation. This study contributes to the development of improved photocatalysis technologies for long-term sewage treatment applications.

Synergistic Enhancement of Oxytetracycline Hydrochloride Removal by UV/ZIF-67 (Co)-Activated Peroxymonosulfate

This study developed a new system for removing antibiotics using UV/ZIF-67 (Co)-activated peroxymonosulfate. The presence of antibiotic organic pollutants in urban sewage presents a substantial challenge for sewage treatment technologies. Due to the persistent chemical stability of antibiotics, their low environmental concentrations, and their resistance to degradation, effectively removing residual antibiotics remains a significant issue in urban wastewater treatment. This study introduces an eco-friendly photocatalytic technology designed to enhance the removal of oxytetracycline (OTC) from municipal wastewater using a UV/ZIF-67 (Co)/PMS system. The results showed that compared with UV, UV/PMS, ZIF-67 (Co), ZIF-67 (Co)/PMS, and UV/ZIF-67 (Co) systems, the UV/ZIF-67 (Co)/PMS system had the highest OTC removal rate. When 10 mg ZIF-67 (Co) and 1 mM PMS were applied to 100 mL 30 mg/L OTC solution, the degradation efficiency reached 87.73% under 400 W ultraviolet light. Increasing the dosage of ZIF-67 (Co) and PMS can improve the removal rate of OTC, but the marginal benefit of additional dosage is reduced. The highest degradation efficiency was observed at weakly acidic pH, which may be due to potential damage to the internal structure of the catalyst and reduced performance under extreme pH conditions. The influence of chloride ions and nitrate ions on the reaction system is minimal, while bicarbonate ions exhibit a significant inhibitory effect on the removal of OTC. The UV/ZIF-67 (Co)/PMS system exhibits adaptability to various water sources, including tap water, Guitang River water, and pure water. The results of free radical identification indicate the presence of hydroxyl and sulfate groups in the UV/ZIF-67 (Co)/PMS system, both of which play important roles in the degradation of OTC. This study offers valuable insights and technical support for the green, efficient, and environmentally friendly removal of antibiotics from urban wastewater.

Revealing the Viable Microbial Community of Biofilm in a Sewage Treatment System Using Propidium Monoazide Combined with Real-Time PCR and Metagenomics.

Microbial community composition, function, and viability are important for biofilm-based sewage treatment technologies. Most studies of microbial communities mainly rely on the total deoxyribonucleic acid (DNA) extracted from the biofilm. However, nucleotide materials released from dead microorganisms may interfere with the analysis of viable microorganisms and their metabolic potential. In this study, we developed a protocol to assess viability as well as viable community composition and function in biofilm in a sewage treatment system using propidium monoazide (PMA) coupled with real-time quantitative polymerase chain reaction (qPCR) and metagenomic technology. The optimal removal of PMA from non-viable cells was achieved by a PMA concentration of 4 μM, incubation in darkness for 5 min, and exposure for 5 min. Simultaneously, the detection limit can reach a viable bacteria proportion of 1%, within the detection concentration range of 102-108 CFU/mL (colony forming unit/mL), showing its effectiveness in removing interference from dead cells. Under the optimal conditions, the result of PMA-metagenomic sequencing revealed that 6.72% to 8.18% of non-viable microorganisms were influenced and the composition and relative abundance of the dominant genera were changed. Overall, this study established a fast, sensitive, and highly specific biofilm viability detection method, which could provide technical support for accurately deciphering the structural composition and function of viable microbial communities in sewage treatment biofilms.

Solutions for urban sanitation: A case study of Imhoff tank technology in Bandung, Dutch East Indies (1917‒1938)

This research investigates how municipalities managed wastewater in the Dutch East Indies in the early 20th century. We focus on Bandung, one of the most important cities in the Dutch East Indies, which transformed into a modern residential area, economic center, and seat of government. This research combines primary data from written sources and field observations using historical-archaeological methods. The written sources include official reports from the Public Works Department, Civil Health Department, Bandung City Council, old maps, sewer network designs, environmental engineering journals, and newspapers published from 1909 to 1941. Using the techno-environmental approach introduced by Martin V. Melosi, this study considers urban technology as a strategic response by decision-makers to address the challenges faced by developing cities in the early 20th century. The study reveals that Bandung City faced environmental problems, such as the natives' habit of defecating in rivers and open spaces, spreading diseases, and potentially polluting river water. These problems arose due to the lack of sanitation facilities and the densely populated settlements, especially in the native and Chinese residential areas. To address these challenges, policymakers, environmental engineers, and researchers initiated the design and implementation of sewers, public toilets, and wastewater treatment plants in 1917. The Municipality integrated sewers with the Imhoff Tank sewage treatment technology developed by researchers and engineers from 1932 to 1938 to introduce circular sewage treatment. Imhoff Tanks was a significant technological innovation in the Dutch East Indies. In the early 20th century, only a handful of cities in the Dutch East Indies, including Bandung, Medan, and Yogyakarta, had integrated sewer networks. Among the cities that did have sewer networks, Bandung pioneered the implementation of the Imhoff Tank. As a result, it emerged as an important laboratory and development center for Bandung and the entire Dutch East Indies. The Imhoff Tank treatment process, which produces clean water, fertilizer, and methane gas that can be used as vehicle fuel, was part of a proactive strategy pioneered by policymakers in Bandung in the early 20th century, reflecting their vision to create a healthy and sustainable city.

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.

Early Introduction and Practice of Activated Sludge Sewage Treatment Technology in Shanghai

Early Introduction and Practice of Activated Sludge Sewage Treatment Technology in Shanghai

Analysis and Design of Sequencing Batch Reactor Basin for Sewage Treatment Plant by using Autocad

bstract: The objectives of this project are to review and evaluate sewage treatment technologies and propose a method to improve or select appropriate technology. Sequencing batch reactor (SBR) is a part of the secondary treatment process of sewage treatment. It is fill and draw-type of activated sludge system involving a single complicated mix reactor where all steps of an activated sludge process take place. The objectives of this project are to review and evaluate sewage treatment technologies and propose a method to improve or select appropriate technology. Sequencing batch reactor (SBR) is a part of the secondary treatment process of sewage treatment. It is fill and draw-type of activated sludge system involving a single complicated mix reactor where all steps of an activated sludge process take place.

Comparative study of the removal of sulfate by UASB in light and dark environment.

At present, the application of sewage treatment technologies is restricted by high sulfate concentrations. In the present work, the sulfate removal was biologically treated using an upflow anaerobic sludge blanket (UASB) in the absence/presence of light. First, the start-up of UASB for the sulfate removal was studied in terms of COD degradation, sulfate removal, and effluent pH. Second, the impacts of different operation parameters (i.e., COD/SO42- ratio, temperature and illumination time) on the UASB performance were explored. Third, the properties of sludge derived from the UASB at different time were analyzed. Results show that after 28days of start-up, the COD removal efficiencies in both the photoreactor and non-photoreactor could reach a range of 85-90% while such reactors could achieve > 90% of sulfate being removed. Besides, higher illumination time could facilitate the removal of pollutants in the photoreactor. To sum up, the present study can provide technical support for the clean removal of sulfate from wastewater using photoreactors.

Activation of peroxymonosulfate (PMS) by rGO supported Co3O4 catalyst for iohexol degradation

Sulphate radical (SO4·-) -based advanced oxidation process (SR-AOP) is a promising sewage treatment technology. Reduced graphene oxide (rGO) supported Co3O4 composites were synthesized by a hydrothermal method for the degradation of iohexol (IOH) in the rGO/Co3O4/peroxymonosulfate (PMS) system. Experimental results show that rGO/Co3O4 possessed much better PMS activated ability than pure GO or Co3O4, which is ascribed to the summation of rGO and Co3O4. The efficiency of rGO/Co3O4 composite, single GO and Co3O4 nanocrystals for the degradation of IOH were 98.7%, 15.8% and 79.8% at 15 min, and their corresponding reaction rate constants (kapp) were 0.21 min−1, 0.0077 min−1 and 0.080 min−1, respectively. The results of active species capture experiment and electron paramagnetic resonance (EPR) experiment, showed that singlet oxygen is the main active species, which is non-radical degradation. rGO is conducive to the electron conduction of Co3O4, thus improving the efficiency of PMS activation. The system is simple and efficient, which is an effective technology to remove IOH.

Application and effect evaluation of membrane bioreactor technology in municipal wastewater treatment

Due to the increasing amount of urban sewage and improved standards in sewage discharge, simple traditional biological sewage treatment fails to meet the needs of municipal sewage treatment. Therefore, to treat wastewater more efficiently, the process of combining biofilm technology with traditional biological wastewater treatment appeared. This paper analyzes the advantages and problems of the combined processes of membrane separation technology and traditional biological sewage treatment technology from and perspective of complementary processes, and puts forward relevant measures to alleviate membrane fouling. The study found that Membrane Bioreactor (MBR) technology occupies a small area, and has a better sewage effluent quality and strong stability, also the sludge output is low. Anaerobic Membrane Bioreactor (AnMBR) technology can increase the effectiveness of removing organic matter and enable resource reuse, which satisfies the demand for low energy consumption. Membrane Aeration Bioreactor (MABR) technology involves bubble-free aeration that greatly improves the quality of sewage effluent, and the production of sludge in MABR technology decreases. Anaerobic ammonium nitrogen membrane bioreactor technology can enhance the efficiency of Anammox bacteria, and the energy consumption and economic cost of this technology are low. Although these membrane combination processes can effectively treat sewage, they can easily be limited by factors such as temperature, microbial communities, and membrane fouling. This paper provides guiding opinions for decision makers in the field of urban sewage treatment so that they can apply appropriate sewage treatment technology to local municipal sewage treatment, promoting the sustainable development of sewage treatment.

Case Study of Deterioration of Mansar Lake and Comparative Study of FAB and SBR Technologies in Sewage Treatment Plant

The deterioration of Mansar Lake, a significant tourist attraction and a vital water resource in India, has become a matter of concern due to the discharge of untreated sewage and industrial effluents. The present study aims to investigate the factors leading to the degradation of Mansar Lake and the effectiveness of two advanced sewage treatment technologies, Fixed Activated Beds (FAB) and Sequencing Batch Reactors (SBR), in treating sewage waste. The study begins with a comprehensive analysis of the factors contributing to the degradation of Mansar Lake, including the inflow of untreated sewage, industrial effluents, and agricultural runoff, as well as the impact of climate change and anthropogenic activities. The research then moves on to the comparative study of FAB and SBR technologies, evaluating their performance in terms of pollutant removal efficiency, energy consumption, and operational costs. The results of the study show that both FAB and SBR technologies are effective in treating sewage waste, with SBR technology having a slight edge in terms of pollutant removal efficiency. However, FAB technology is more cost-effective and energy-efficient, making it a more viable option for developing countries with limited resources. The study concludes with recommendations for the implementation of FAB technology in the sewage treatment plant serving Mansar Lake, as well as the need for stricter regulations and enforcement to prevent the inflow of untreated sewage and industrial effluents into the lake. The study also emphasizes the importance of public awareness and education in preserving the lake's ecological balance and promoting sustainable tourism practices. Mansar Lake, sewage treatment, FAB technology, SBR technology, pollutant removal efficiency, cost-effectiveness, energy efficiency, sustainable tourism.

A review on sustainable sewage treatment technologies applicable to semi-arid regions

Sustainability in the context of Wastewater Treatment Plants (WWTPs) is manifested when the principles of circular economy are prioritized, and the use of by-products takes center stage. From this perspective, a notable gap exists in the literature, as no bibliometric analysis has evaluated the sustainability of sewage treatment technologies in semi-arid climates. Addressing this, the current study aims to contextualize, map, and analyze the evolution and trends of sustainable WWTPs through bibliometric analyses, to assess the hypothesis of the existence of sustainable wastewater treatment plants and, in the affirmative, to evaluate which ones are best suited to the semi-arid climate. The research utilized documentary research data. To this end, the VosViewer software was employed to map information from titles and abstracts. Furthermore, the Bibliometrix software was used for bibliometric analyses. Additionally, a systematic analysis of selected articles was carried out to validate the results obtained in the integrative analysis. The integrative review revealed an evolution in scientific production related to the sustainability of WWTPs, with a significant increase in publications over time. As a result, it can be observed that sewage treatment technologies such as constructed wetlands, pond systems, sand filtration, and septic tanks were highlighted as more sustainable and applicable approaches in semi-arid regions compared to other sewage treatment technologies analyzed. Bibliometric analysis identified prominent authors, leading countries in scientific production, and key scientific journals in the field. The validation of results through systematic analyses reinforced the reliability and robustness of the information obtained in the study. As seen, this study contributes to a significant advancement in knowledge about sustainable sewage treatment in semi-arid regions, providing relevant insights for public and private stakeholders in making informed and sustainable decisions.

Comparison of the typical traditional and advanced sewage treatment technologies

Comparison of the typical traditional and advanced sewage treatment technologies

Application prospect of new sewage treatment technology in urban environment

Application prospect of new sewage treatment technology in urban environment

Research on the Technical Model of Resource Utilization of Rural Domestic Sewage

At present, China’s rural sewage treatment technology is mostly used in municipal sewage treatment methods, with high energy consumption and complicated operation and maintenance. Through analyzing the problem of rural sewage management, we discussed the necessity and feasibility of rural sewage resource utilization, presented the principles that should be followed in the resource utilization according to local conditions, promoting the treatment, economic rationality, and ecological safety, and Summarized the technical models of irrigation utilization, ecological dissipation and decentralized on-site utilization for the resource utilization of rural domestic wastewater. The expansion of the resource utilization model will be more conducive to reducing the cost of rural sewage management and enhancing the quality of the rural environment and human settlements.

Technical and Economic Feasibility of Different Urban Sludge Treatment Technologies

Currently, the level of urban sewage treatment technology in China is very mature, but the development of urban sludge technology lags behind. In some cities, sludge has not been effectively treated for a long time, emitting foul odors that seriously affect people’s daily lives. Moreover, heavy metals and pathogens cause corrosion and damage to the land. Therefore, it is particularly important to choose an efficient and environmentally friendly approach to urban sludge treatment. This article lists three routes for urban sludge treatment. The Ebsilon software was used to simulate the co-combustion process of coal and sludge in the sludge incineration route. Based on domestic and international research results, the technical characteristics of sludge pyrolysis and composting were analyzed. The research method of comparative analysis was adopted to comprehensively compare and analyze the technical characteristics and return on investment (ROI) of the three routes. This research method can intuitively demonstrate the advantages and disadvantages of the three routes, and accurately and quantitatively determine the best route. In conclusion, Route 1: the comprehensive treatment process of drying and incineration is currently the most suitable route for China’s development prospects. It has the most mature technology and the widest range of applications, achieving the highest efficiency in sludge treatment. In the foreseeable future, sludge incineration technology will remain the cornerstone of sludge treatment and disposal in China.