Domestic Sewage Treatment System Research Articles

Hybrid life-cycle and hierarchical archimedean copula analyses for identifying pathways of greenhouse gas mitigation in domestic sewage treatment systems

Electricity consumption and anaerobic reactions cause direct and indirect greenhouse gas (GHG) emissions within domestic sewage treatment systems (DSTSs). GHG emissions in DSTSs were influenced by the sewage quantity and the efficacy of treatment technologies. To address combined effects of these variables, this study presented an approach for identifying pathways for GHG mitigation within the DSTSs of cities under climate change and socio-economic development, through combining life cycle analysis (LCA) and the Hierarchical Archimedean copula (HAC) methods. The approach was innovative in the following aspects: 1) quantifying the GHG emissions of the DSTSs; 2) identifying the correlations among temperature changes, socioeconomic development, and domestic sewage quantity, and 3) predicting the future fluctuations in GHG emissions from the DSTSs. The effectiveness of the proposed approach was validated through its application to an urban agglomeration in the Pearl River Delta (PRD), China. To identify the potentials of GHG mitigation in the DSTSs, two pathways (i.e., general and optimized) were proposed according to the different technical choices for establishing facilities from 2021 to 2030. The results indicated that GHG emissions from the DSTS in the PRD were [3.01, 4.96] Mt CO2eq in 2021, with substantial contributions from Shenzhen and Guangzhou. Moreover, GHG emissions from the sewage treatment facilities based on Anaerobic-Anoxic-Axic (AAO) technology were higher than those based on other technologies. Under the optimized pathway, GHG emissions, contributed by the technologies of Continuous Cycle Aeration System (CASS) and Oxidation Ditch (OD), were the lowest. Through the results of correlation analysis, the impact of socioeconomic development on domestic sewage quantities was more significant than that of climate change. Domestic sewage quantities in the cities of the PRD would increase by 4.10%–28.38%, 17.14%–26.01%, and 18.15%–26.50% from 2022 to 2030 under three Representative Concentration Pathways (RCPs) 2.6, 4.5, and 8.5. These findings demonstrated that the capacities of domestic sewage treatment facilities in most cities of the PRD should be substantially improved from 0.12 to 2.99 times between 2022 and 2030. Under the optimized pathway, the future GHG emissions of the CASS method would be the lowest, followed by the OD method.

Treatment of domestic effluents using sustainable biofilter methods

The discharge of effluents is a permanent environmental and sanitation concern. Efficient water management must include water treatment and reuse. It is therefore necessary to study treatment systems to improve their performance throughout the entire chain, from drinking water to wastewater or, more specifically, waste effluent. Currently, technologies using bio-filtration processes have proven to be an effective and low-cost method for treating industrial effluents and domestic sewage. In this study, a low-cost domestic sewage treatment system made up of biofilters and pipes was built on a bench model as a means of teaching practical classes, and its efficiency was also studied. The results showed that the equipment can be made from recyclable material and is low-cost, easy to detail technically and easy to handle and operate. The students involved can easily replicate the technology in their communities, thus spreading low-cost sanitation treatment technologies to low-income populations without access to conventional sanitation systems. The parameters pH, turbidity, chlorination, temperature, and electrical conductivity were all at acceptable levels for discharge into receiving bodies and domestic use.

Analysis of fecal pollution load factor from septic tanks of residential area (study case: Bandung City, Indonesia)

According to the Ministry of Environment and Forestry, 2017, domestic waste is the most significant contributor to pollution sources in the Citarum watershed (62.16%) and Bandung City (94.15%). To overcome the problem, planning for infrastructure development and improvement of the domestic sewage treatment system is necessary. One of the essential characteristic parameters, which is the subject of this study, is the pollutant load factor parameter in the city of Bandung. Compared to sewage pipelines, the domination of domestic wastewater treatment in Bandung is the On-site Sanitation System (OSS) (38.47%), and the most widely used type of OSS is a septic tank. For this reason, thirty fecal sludge samples were taken from two fecal disposal points in Bandung City, and the concentrations of TSS, COD, BOD, and Ammonia were then analyzed. Based on the results of the study, the range of fecal sludge pollutant load factor for TSS in Bandung City is 57.28 g / person/day – 1,064 g / person/day with an average value of 546.39 g / person/day, the range for total COD is 30.06 g / person/day – 294.99 g /person/day with an average of 294.99 g / person/day, the total BOD range is 14.05 g /person/day – 504.97 g / person/day with an average of 175.5 g / person/day, and ammonia range 1.61 g/person/day – 3.11 g/person/day with an average of 2.62 g/person/day. Based on fecal sludge data, the result can be considered a recommendation to re-determine the main domestic wastewater pollution indicator generation. The new suggestions can be used to design an adequate domestic wastewater treatment system, especially in Bandung. The pollutant load factors can also be used to estimate the pollution loading of wastewater generated by present and future populations. It is important in urban growth planning.

Performance analysis of decentralized sewage solutions for multifamily residential condominiums in Aracaju

The adoption of decentralized sewage treatment systems appears as an alternative for regions lacking sanitary infrastructure. Regarding Brazilian municipalities, they presented, in 2020, a sewage collection service rate for the urban population equal to 63.2%. Also, according to data from the National Sanitation Information System, in the municipality of Aracaju, capital of the state of Sergipe, the rate of collection of generated sewage is only 53.5%. Due this reality, investment in individual effluent treatment systems becomes a valuable alternative for areas that lack of sanitary infrastructure. In this work, the performance of domestic sewage treatment systems, used as individual treatment solutions in two multifamily condominiums in the capital of Sergipe, was evaluated. Physical-chemical monitoring of the individual sewage treatment systems was carried out, and the results indicated negative efficiencies in most of the analyzed parameters. As for the requirements of the current environmental legislation for the release of effluents, there was non-compliance with the legislation in almost all the time of observation. The lack of systems operation supervision by public agencies leads to failures that cause degradation of groundwater and surface water. Moreover, there is a lack of commitment to inspections and maintenance of the systems by those responsible for the condominiums. According to the types of solutions adopted, treated sewage with higher quality should be achieved and, thus, effluents with high loads of pollutants would not be released into water bodies.

Application of activated carbon functionalized with graphene oxide for efficient removal of COVID-19 treatment-related pharmaceuticals from water

Currently, the COVID-19 pandemic has been increasing the consumption of some drugs, such as chloroquine (CQN) and dipyrone (DIP), which are continuously discharged into water resources through domestic sewage treatment systems. The presence of these drugs in water bodies is worrisome due to their high toxicity, which makes crucial their monitoring and removal, especially by means of advanced technologies. Given this scenario, a new adsorbent material was synthesized through the combination of babassu coconut activated carbon and graphene oxide (GAC-GO). This study was evaluated in batch adsorption processes, aiming at the treatment of water contaminated with CQN and DIP. Characterization analyzes using physicochemical and spectroscopic techniques indicated that the GAC-GO functionalization was successfully performed. The equilibrium time of the adsorption process was 18 and 12 h for CQN and DIP, respectively. Kinetic and isothermal data better fitted to pseudo-second-order and Langmuir models for both drugs. Thermodynamic parameters showed that the process is endothermic and the maximum adsorption capacities of CQN and DIP were 37.65 and 62.43 mg g−1, respectively, both at 318 K. The study of the effect of ionic strength, which simulates a real effluent, demonstrated that the synthesized adsorbent has potential application for the treatment of effluents. Furthermore, satisfactory removal rates were verified for the removal of other contaminants in both simple solutions and synthetic mixtures, evidencing the versatile profile of the adsorbent.

A Comparative Study of Improvement of Phycoremediation Using a Consortium of Microalgae in Municipal Wastewater Treatment Pond Systems as an Alternative Solution to Africa’s Sanitation Challenges

The reuse of wastewater has been observed as a viable option to cope with increasing water stress in Africa. The present case studies evaluated the optimization of the process of phycoremediation as an alternative low-cost green treatment technology in two municipality wastewater treatment pond systems that make up the largest number of domestic sewage treatment systems on the African continent. A consortium of specific microalgae (Chlorella vulgaris and Chlorella protothecoides) was used to improve the treatment capacity of domestic wastewater at two operational municipality wastewater pond systems under different environmental conditions in South Africa. Pre- and post-phycoremediation optimization through mass inoculation of a consortium of microalgae, over a period of one year under different environmental conditions, were compared. It was evident that the higher reduction of total phosphates (74.4%) in the effluent, after treatment with a consortium of microalgae at the Motetema pond system, was possibly related to (1) the dominance of the algal taxa C. protothecoides (52%), and to a lesser extent C. vulgaris (36%), (2) more cloudless days, (3) higher air temperature, and (4) a higher domestic wastewater strength. In the case of the Brandwag pond treatment system, the higher reduction of total nitrogen can possibly be related to the dominance of C. vulgaris, different weather conditions, and lower domestic wastewater strength. The nutrient reduction data from the current study clearly presented compelling evidence in terms of the feasibility for use of this technology in developing countries to reduce nutrient loads from domestic wastewater effluent.

Design of modular constructed wetland and its effect on rural domestic sewage treatment

According to the characteristics of large amount and scattered discharge of domestic sewage in rural residential environment, a rural domestic sewage treatment system based on modular constructed wetland was designed. The wetland is composed of three modules with a treatment scale of 30 m3/d. The plants are Arundo donax and Typha, and three kinds of filter media are selected to fill the substrate. The treatment capacity and treatment effect of the modular constructed wetland were studied through experiments. The results showed that the modular constructed wetland had a good treatment effect on sewage, and the average removal rates of BOD5, COD, SS, NH3-N, TN and TP were 83.3%, 83.5%, 90.5%, 70%, 66.9% and 68.3%, respectively. The treated water quality can meet the first class standard of water pollutants discharge standard for rural domestic sewage treatment and disposal facilities (DB37/3693-2019) of Shandong Province. The modular constructed wetland can be used to treat rural scattered domestic sewage with strong applicability, flexibility and feasibility.

Microbiome taxonomic and functional profiles of two domestic sewage treatment systems.

Anaerobic systems for domestic sewage treatment, like septic tanks and anaerobic filters, are used in developing countries due to favorable economic and functional features. The anaerobic filter is used for the treatment of the septic tank effluent, to improve the COD removal efficiency of the system. The microbial composition and diversity of the microbiome from two wastewater treatment systems (factory and rural school) were compared through 16S rRNA gene sequencing using MiSeq 2 × 250bp Illumina sequencing platform. Additionally, 16S rRNA data were used to predict the functional profile of the microbial communities using PICRUSt2. Results indicated that hydrogenotrophic methanogens, like Methanobacterium, were found in higher abundance in both systems compared to acetotrophic methanogens belonging to Methanosaeta genus. Also, important syntrophic microorganisms (Smithella, Syntrophus, Syntrophobacter) were found in the factory and rural school wastewater treatment systems. Microbial communities were also compared between stages (septic tank and anaerobic filter) of each wastewater treatment stage, revealing that, in the case of the rural school, both microbial communities were quite similar most likely due to hydraulic short-circuit issues. Meanwhile, in the factory, microbial communities from the septic tank and anaerobic filter were different. The school system showed lower COD removal rates (2-30%), which were probably related to a higher abundance of Firmicutes members in addition to the hydraulic short-circuit and low abundance of Chloroflexi members. On the other hand, the fiberglass factory presented higher COD removal rates (60-83%), harboring phyla reported as the core microbiome of anaerobic digesters (Bacteroidetes, Chloroflexi, and Proteobacteria phyla). The knowledge of the structure and composition of wastewater treatment systems may provide support for the improvement of the pollutant removal in anaerobic process.

Biogas standard system in China

Standardization of biogas technology is immensely important for the promotion of the biogas industry worldwide. China has built a complete biogas standard system, which is divided into common, household biogas, biogas engineering, biogas digester for domestic sewage treatment, output utilization, and service system standards. The problems and potential barriers for biogas standardization in China are analyzed and come down to sluggish standard, overlapped standard, government-dominated standard, and lagging international standard. Accordingly, all potential biogas standards should be evaluated and placed under the same department. China Biogas Society and China Association of Rural Energy Industry play leading roles in developing enterprise or group/association biogas standards and ISO biogas standards. The bio-natural gas standard system and experimental standardization should be developed as well to replenish biogas standard system. A paradigm shift in biogas standardization should be from government-dominated to market-oriented model. The lessons learned for other developing countries includes expanding standardization to multi-aspects to realize full lifecycle control and management, building rapid responding mechanism of standardization to adopt industry transformation, integrating outdated standards into new versions, and establishing market-based standard system.

Design of Domestic Sewage Treatment System Based on Programmable Logic Controller

This paper focuses on the design of software and hardware for the purification and recycling of domestic sewage discharged from a residential area. According to the characteristics of domestic sewage, the process used in this paper is determined to be Sequencing Batch Reactor (SBR) process and the allocation of system input/output (I/O) port. According to the determination of the process flow to select appropriate instruments, sensors and other equipment, using Programmable Logic Controller (PLC) to design the system in manual mode and automatic mode of the program respectively, to achieve the function of sewage treatment.

Activated sludge bacterial communities of typical wastewater treatment plants: distinct genera identification and metabolic potential differential analysis

To investigate the differences in activated sludge microbial communities of different wastewater treatment plants (WWTPs) and understand their metabolic potentials, we sampled sludge from every biological treatment unit of 5 full-scale waste water treatment systems in 3 typical Chinese municipal WWTPs. The microbial communities and overall metabolic patterns were not only affected by influent characteristics but also varied between different biological treatment units. Distinct genera in different wastewater treatment systems were identified. The important microorganisms in domestic sewage treatment systems were unclassified SHA-20, Caldilinea, Dechloromonas, and unclassified genera from Rhodospirilaceae and Caldilineaceae. The important microorganisms in dyeing wastewater treatment systems were Nitrospira, Sphingobacteriales, Thiobacillus, Sinobacteraceae and Comamonadaceae. Compared with the obvious differences in microbial community composition, the metabolic potential showed no significant differences.

Prevalence and transmission of antibiotic resistance and microbiota between humans and water environments

The transmission routes for antibiotic resistance genes (ARGs) and microbiota between humans and water environments is poorly characterized. Here, we used high-throughput qPCR analyses and 16S rRNA gene sequencing to examine the occurrence and abundance of antibiotic resistance genes and microbiota in both healthy humans and associated water environments from a Chinese village. Humans carried the most diverse assemblage of ARGs, with 234 different ARGs being detected. The total abundance of ARGs in feces, on skin, and in the effluent from domestic sewage treatment systems were approximately 23, 2, and 7 times higher than their abundance in river samples. In total, 53 ARGs and 28 bacteria genera that were present in human feces could also be found in the influent and effluent of rural sewage treatment systems, and also downstream of the effluent release point. We identified the bacterial taxa that showed a significant association with ARGs (P < 0.01, r > 0.8) by network analysis, supporting the idea that these bacteria could carry some ARGs and transfer between humans and the environment. Analysis of ARGs and microbiota in humans and in water environments helps to define the transmission routes and dynamics of antibiotic resistance within these environments. This study highlights human contribution to the load of ARGs into the environment and suggests means to prevent such dissemination.

Potential of resource recovery in UASB/trickling filter systems treating domestic sewage in developing countries

This paper aims to present perspectives for energy (thermal and electric) and nutrient (N and S) recovery in domestic sewage treatment systems comprised of upflow anaerobic sludge blanket (UASB) reactors followed by sponge-bed trickling filters (SBTF) in developing countries. The resource recovery potential was characterized, taking into account 114 countries and a corresponding population of 968.9 million inhabitants living in the tropical world, which were grouped into three desired ranges in terms of cities' size. For each of these clusters, a technological arrangement flow-sheet was proposed, depending on their technical and economic viability from our best experience. Considering the population living in cities over 100, 000 inhabitants, the potential of energy and nutrient recovery via the sewage treatment scheme would be sufficient to generate electricity for approximately 3.2 million residents, as well as thermal energy for drying purposes that could result in a 24% volume reduction of sludge to be transported and disposed of in landfills. The results show that UASB/SBTF systems can play a very important role in the sanitation and environmental sector towards more sustainable sewage treatment plants.

Rural sewage treatment processing in Yongjia County, Zhejiang Province

Issues regarding water pollution in rural areas of China have garnered increased attention over the years. Further discussion on the circumstances and results of existing domestic sewage treatment methods may serve as an appropriate reference in solving these important issues. This article explored the current conditions of water contamination in rural areas of China, introduced the characteristics and effects of applicable sewage treatment technology, and summarized the results of the planning, installation, and operation of rural sewage treatment facilities in Yongjia County in Zhejiang Province. However, relying on a single technical design rule is not adequate for solving the practical problems that these villages face. Instead, methods of planning rural sewage treatment should be adapted to better suit local conditions and different residential forms. It is crucial, ultimately, for any domestic sewage treatment system in a rural area to be commissioned, engineered, and maintained by a market-oriented professional company.

Design and Efficiency of a Domestic Sewage Treatment System with Microorganism-membrane on Island Based on Entropy Theory

Domestic sewage treatment by water drainage network plus septic tank is not suitable on very small islands because of traffic and urban infrastructure problem. This study deals with a microorganism-membrane domestic sewage treatment system on small islands, which can degrade and clean the domestic sewage locally by effective microorganism and membrane system and makes the emission in market. Eight kinds of commercial complex microorganisms decompose powder were chosen to analysis the activities of protease, lipase, cellulose and amylase. And relating model based on entropy theory was constructed to evaluate the effect of enzyme activity, then the best commercial complex microorganism decompose powder was confirmed. The designed microorganism- membrane wastewater treatment system was applied to treat domestic sewage on a small island. The results showed that the removal rate of organic matters including the five-day Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD) and ammonia nitrogen (NH 3-N) reached more than 98%. The removal rate of Total Dissolved Salts (TDS) of the outlet water was higher than 99%. This system was especially suitable for small islands domestic wastewater treatment.

Occurrence and removal of antibiotic resistance genes in municipal wastewater and rural domestic sewage treatment systems in eastern China

Antibiotic resistance genes (ARGs) are emerging environmental contaminants and pose a threat to public health. In this study, four tetracycline resistance genes (tetM, tetO, tetQ and tetW) and two sulfonamide resistance genes (sulI and sulII) were evaluated in 4 municipal wastewater and 8 rural domestic sewage treatment systems with different wastewater handling abilities and treatment processes using quantitative polymerase chain reaction (qPCR). In the influents, the relative abundance of different ARGs showed significant variations among the sampling sites. In addition, significant correlations (tetQ: R2=0.712, P<0.05; tetO: R2=0.394, P<0.05) between the gene copy numbers and wastewater-receiving capacity were observed. Statistical analysis revealed a positive correlation (R2=0.756, P<0.05) between the gene copy numbers of sulI and intI1, whereas the gene numbers of tetM and sulI were strongly correlated with 16S rDNA. Significant reductions (1–3 orders of magnitude) in ARGs were observed in municipal wastewater treatment systems, but a smaller reduction was found in the rural domestic sewage treatment systems. These results provide insights into the occurrence and removal of ARGs in wastewater treatment systems in both rural and urban areas in eastern China.

Survey of Rural Domestic Sewage Treatment Systems of Songjiang District in Shanghai, China

Due to the relatively unprogressive economic and social development of Songjiang rural areas of Shanghai city in China, the degree of rural domestic sewage treatment was relatively weak and hysteretic. The rural sewage treatment systems of Songjiang district were investigated through field survey. Finally, the systems of soil infiltration-constructed wetland and combinatorial biofilter, with obvious advantages, were proposed to popularize in Songjiang rural areas more suitably.

Technical Problems Ensuing From UASB Reactor Application in Domestic Wastewater Treatment without Pre-Treatment

The performance and stability of a domestic sewage treatment system consisting of an upflow anaerobic sludge blanket (UASB) reactor were assessed. This was to come up with a technical evaluation of using such a system to treat directly such wastewater containing high amounts of suspended solids (SS) in developing countries like Lesotho. Through time, the evolution of the sludge bed was monitored closely, in terms of accumulation of particulate matter and its general quality. The average total chemical oxygen demand (CODt) of the wastewater was 522 mgL-1, and the system could remove 80 % of the organic matter. The sludge production in the reactor system was high (up to 70 % of influent chemical oxygen demand found as suspended solid), necessitating repeated sludge discharges from the reactor, on average every 100 days. Considering the delicate balance of the methanogens in anaerobic reactors, perturbations of the microbiota arose following the sludge extractions, and these promoted reactor imbalance. This further brought about a decrease in reactor performance and hence of the general sustainability of the UASB process when treating domestic sewage directly. In addition, the system could not remove the macronutrients nitrogen and phosphorus. Additional treatment steps would be necessary to remove the suspended solids and nutrients, and thus to effectively treat such a wastewater.

Anaerobic treatment of domestic sewage: established technologies and perspectives

The use of anaerobic reactors for domestic sewage treatment has increased significantly since the UASB configuration started to be efficiently applied for this purpose in the beginning of the 1980s. Nowadays, hundreds of UASB reactors, or similar anaerobic units, are used in domestic sewage treatment systems, particularly in developing countries. These units have been operated at ambient temperature, normally higher than 20 degrees C, at hydraulic detention time in the range of 6 to 10 hours, and organic loading rates lower than 3.0 kg COD.m(-3).d(-1). They have presented COD removal efficiencies in the range of 65% to 80%. Besides, new configurations have been developed and assayed in research centres, aiming to amplify the range of application and to improve process performance. At the same time, research is being conducted on the post-treatment of anaerobic effluents attempting to offer alternatives to the existing conventional systems. It takes into consideration not only sanitation and environmental protection, but also considers resources conservation at lower construction and running costs as the main supporting concepts for further development. This text presents some aspects of the consolidated technologies and suggests on further developments in the conception of domestic sewage treatment systems having the anaerobic process as their core.

Properties of a new strain of Nitrosomonas isolated from an aerobic biofilm in a domestic sewage-treatment system

A new ammonia-oxidizing strain, isolated from an aerobic biofilm in a domestic sewage-treatment system, was identified as a species of Nitrosomonas different from Nitrosomonas europaea. This strain had morphological features and growth characteristics typical of members of the genus Nitrosomonas. The G+C content of the DNA of this strain was 48.5 mol%, being lower than that of known strains of N. europaea. The extent of the homology between the DNA of this strain and that of other strains of N. europaea was less than 30%. After cells of this isolate, immobilized in a polyacrylamide gel, had been added to the aerobic reactor of a laboratory-scale sewage-treatment system, the concentration of ammonium nitrogen in the effluent decreased to 2 mg/ l without the accumulation of nitrite, and removal of more than 70% of the nitrogen from the input sewage was achieved.