Domestic Wastewater Treatment Research Articles

Sequential anaerobic–intermittently aerated treatment of textile and domestic wastewater

Sequential anaerobic–intermittently aerated treatment of textile and domestic wastewater

UTILIZATION OF CASSAVA PEEL AND CHITOSAN FOR THE PRODUCTION OF HYDROGEL AS A SUSTAINABLE SOLUTION FOR DOMESTIC WASTEWATER TREATMENT

Water pollution is a significant environmental issue, especially in developing countries where domestic wastewater often contains a high concentration of pollutants, posing risks to public health and the environment. Hydrogel from cassava peel and chitosan shows promise as a bioadsorbent for domestic wastewater treatment, but its capacity and optimal production temperature have not been fully studied. The study aimed to investigate the characteristics of hydrogel from cassava peel and chitosan, the optimal temperature for hydrogel production, and the efficacy of hydrogel as a bioadsorbent for domestic wastewater treatment. The study involved four stages: cellulose isolation, hydrogel preparation, wastewater treatment experimentation, and data analysis. The results showed that chitosan hydrogel synthesized at 750C had superior efficiency, achieving an optimal outcome of 88% in the treatment of household wastewater using a triad of chitosan hydrogel pellets. The degree of cross-linking in chitosan hydrogel diminished with an increase in heating temperature

Ceramic membranes production using quartzite waste for treatment of domestic wastewater

Ceramic membranes production using quartzite waste for treatment of domestic wastewater

Optimization of condensing tray shapes for a multi‐effect solar still coupled with parabolic solar collectors for domestic wastewater treatment: A comparative study

AbstractThe issue of water depletion emerged as a life‐threatening problem for the world due to urbanization, groundwater over‐extraction, industrialization, and global warming. Current study aimed to address this issue by proposing a solution to distill wastewater using a multi‐effect solar still. The study optimizes two condensation tray shapes, U and V, based on the yield produced and the temperatures achieved. Two solar still units with four stages of U and V‐shaped trays were connected to a parabolic solar collector. To determine the optimal tray shapes, a rigorous optimization process was carried out using SolidWorks 2020. The optimization process yielded optimum heat flux values of 3.04e01 and 2.84e01 W/m2 for U and V‐shaped trays, respectively. Higher the value of heat flux suggested more energy available for condensation. Which was corroborated by physical findings that the U‐shaped condensation tray was more efficient, producing an average per day yield of 2.519 L/m2 h compared to the V‐shaped tray's yield of 2.041 L/m2 h. The findings provide strong evidence that the U‐shape is a better tray shape for condensation purposes. Maximum yield for both units was observed during the peak temperature time between (13:00–15:00 h), indicating a direct correlation between yield and atmospheric temperature.

Application of Nano Bubble Aeration Technology in Domestic Wastewater Treatment: Optimization of Gas Flow and Reaction Time

Nano bubble aeration is an emerging technology with significant potential in wastewater treatment, particularly for removing suspended solids and organic matter. This study investigates the application of nano bubble aeration in the treatment of domestic wastewater, focusing on the reduction of chemical oxygen demand (COD) and total suspended solids (TSS). Nano bubbles, with diameters ranging from tens of nanometers to a few micrometers, exhibit slower rising velocities and prolonged stability in water due to their negatively charged surfaces. Various nano bubble air flow rates were tested over 90-minute intervals to determine the optimal treatment conditions. The results indicate that a flow rate of 2 liters per minute achieves the highest treatment efficiency, reducing COD by 84.73% and TSS by 77.51%. Increasing the flow rate beyond this level showed minimal improvement, demonstrating that 2 liters per minute is the optimal flow rate for efficient wastewater treatment using nano bubble aeration. This research highlights the advantages of nano bubble technology in enhancing the treatment efficiency of suspended solids and organic matter in wastewater.

Enhancing Domestic Wastewater Treatment: Integrating Vermifiltration and Biochar for Heavy metal and Microplastic Reduction and By-Product Utilization

Enhancing Domestic Wastewater Treatment: Integrating Vermifiltration and Biochar for Heavy metal and Microplastic Reduction and By-Product Utilization

Efficiency of Optimized Fabrication Process for Light-absorbing Membranes from Sewage Sludge Applied in Solar-driven Steam Generation Systems

Solar-driven evaporation systems have been studied to provide clean water, especially for islandic areas. Carbon materials made from sludge in domestic wastewater treatment plants have been studied to produce light-absorbing membranes in solar-to-steam (STS) systems. However, the technical limitation of this method is that the water evaporation rate is still low. In this study, the process of manufacturing light-absorbing membranes was optimized to simplify the process while increasing the water evaporation rate and testing the application of converting seawater into fresh water. The optimal evaporation rate was 2.65 kg.m-2.h-1, higher than the system using vacuum drying membranes (1.88 kg.m-2.h-1) under 0.6 kW/m2 illumination conditions. When illuminated, the surface temperature of the TN_0.1 light-absorbing membrane reached 36.5°C, meaning 2.5°C higher than that of the reference membrane (without carbon material). The results of analyzing some anion and cation indicators in the harvested water showed that the fabricated STS systems could be applied well to convert seawater into fresh water for domestic use. Especially, the treatment efficiencies for , , , reach 99.87%, 94.35%, 99.5%, 99.98%, and 99.44%, respectively.

Lack of wastewater treatment in a small town drives the spread of ESBL-producing Escherichia coli in irrigation waters.

Antibiotic resistance (ABR) is a critical and growing global challenge, especially in low- and middle-income countries. Ecuador has made great progress in connecting households to piped water supplies; however, the collection and treatment of domestic wastewater has lagged. This infrastructural gap may be accelerating the spread of ABR into surface waters used downstream for irrigation. We studied the contributions of a small town in Ecuador to the prevalence of extended-spectrum β-lactamase-producing Escherichia coli in a glacial stream used for irrigating crops. The study analyzed water samples upstream (n=60) and downstream (n=60) of the town of Píntag as well as 30 lettuce samples irrigated by surface waters downstream of the town. A subset of third generation cephalosporin resistant E. coli (3GCR-EC) isolates (n=58) were sequenced to characterize antibiotic resistance genes and pathogenic lineages. Our results showed that there was nearly a three-log increase in mean E. coli colony forming units in the downstream samples versus upstream. At the upstream sites above the town of Píntag, 6.7% of water samples were positive for 3GCR-EC compared to 100% of samples collected at the downstream sites. Additionally, 70.1% of sequenced 3GCR-EC isolates collected at downstream sites carried blaCTX-M genes and 3.4% belonged to pandemic lineages ST131 and ST10. As countries develop household piped water infrastructure, attention should focus on how the lack of domestic wastewater collection and treatment may accelerate the spread of ABR in waterways and the food system.

Comparative analysis and application of soft sensor models in domestic wastewater treatment for advancing sustainability

ABSTRACT This study focuses on the development and evaluation of soft sensor models for predicting NH3-N values in a wastewater treatment process. The study compares the performance of linear regression (LR), neural networks (NN) and random forest regression (RFR) models. The proposed methodology involves optimizing the sequencing batch reactor process using artificial intelligence and an automatic control system. Real-time NH3-N values are obtained by inputting data from electronic conductivity and temperature sensors into the prediction models. Once the predicted NH3-N value falls below the effluent standard, the cycle ends, improving energy efficiency and sustainability by cutting down the agitator and aerator. The research results demonstrate that the RNN-based NH3-N soft sensor built in this study exhibits the best performance, which is promising for wastewater treatment process optimization and evaluation. The results show that sensor model NNR[0.5Y]H exhibits exceptional performance, utilizing recurrent neural network with 5-step input delays. Sensor NNR[0.5Y]H exhibits an R2 of 0.921, an RMSE of 6.110, and an MAE of 4.558. Based on the findings, recurrent neural network (RNN) variants emerge as the most effective modeling technique due to their ability to capture temporal dependencies and handle variable-length sequences. This study provides satisfied performance results for the NNR[0.5Y]H soft sensor model in NH3-N monitoring and process optimization in wastewater treatment, highlighting the effectiveness of recurrent neural networks and their contribution to improving interpretability, accuracy, and adaptability of soft sensor models.

Use of embedding immobilized biofillers to improve hydrolysis acidification efficiency in domestic wastewater treatment

This study evaluated the effectiveness of embedding immobilization technology in wastewater treatment and its capacity to enhance the hydrolysis acidification process. Based on this technology, a stable anaerobic environment has been maintained. Results showed that the rates of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) conversion both exceeded 98 % under short hydraulic retention time (HRT = 2h) and ambient temperature. Notably, acetic acid and propionic acid comprised up to 90.9 % of the total volatile fatty acids in the effluent, providing suitable carbon sources for downstream denitrification. 16S rRNA gene sequencing indicated that biofillers effectively enriched and retained functional bacteria, causing norank_Anaerolineaceae (11.6 %-29.7 %) and norank_Bacteroidetes_vadinHA17 (10.8 %-14.9 %) as the dominant genera in the reactor, which were crucial for refractory organic matter degradation. Immobilized biofillers effectively improved wastewater biodegradability, supporting a stable microbial community with high DON and DOP conversion rates as well as increased VFA accumulation.

Performance Evaluation of a Pilot-Scale Constructed Wetland with Typha latifolia for Remediation of Domestic Wastewater in Zimbabwe

The management of wastewater remains a challenge, particularly in developing countries. The potential use of constructed wetlands to treat wastewater is promising but their contaminant removal efficiencies, particularly in a tropical country such as Zimbabwe, are not fully understood. A pilot-scale study was undertaken in Zimbabwe to evaluate the efficiency of vertical-flow constructed wetlands planted with Typha latifolia in the treatment of domestic wastewater. Four pilot subsurface vertical-flow constructed wetland units (measuring 1 m × 1 m × 1.1 m) were built from concrete. The units were filled with waste rock from a nickel mine. Three units were planted with Typha latifolia while the fourth one was left unplanted, acting as the control. Each unit was loaded with wastewater at a rate of 220 dm3/day. Physico-chemical and bacteriological parameters were analyzed during the winter season. Physico-chemical and bacterial contaminant concentrations were significantly lower in the effluent than in the influent, and the system achieved maximum removals for BOD5, COD, TDS, TSS, nitrates, phosphates, phosphate pentoxide, phosphorus, and E. coli of 56.01%, 82.87%, 30.61%, 90.40% 17.26%, 35.80%, 36.19%, 40.64%, and 90.28%, respectively. The study shows that constructed wetland systems can be successfully established for the removal of physical, chemical, and microbial contaminants from domestic wastewater.

The variation of resistome, mobilome and pathogen in domestic and industrial wastewater treatment systems

Wastewater treatment plants (WWTPs), including both domestic and industrial facilities, are key contributors to antibiotic resistance genes (ARGs) and human pathogens in the environment. However, the characteristics and dissemination mechanisms of ARGs in domestic (SD) and industrial (SI) wastewater treatment systems remain unclear, leading to uncertainties in risk assessment. Based on metagenomic analysis, we observed significant differences in the compositions of resistome (ARGs and metal resistance genes, MRGs), mobilome (mobile genetic elements, MGEs), and bacterial community between SD and SI. SI exhibited lower diversity of ARGs but higher abundance of MRGs compared to SD. The removal efficiency of resistome was lower in the SI than that in the SD. MGEs emerged as the primary driver of ARG dissemination in the WWTPs, followed by the bacterial community. Environmental conditions (physicochemical parameters, heavy metals, and antibiotics) indirectly influenced the variation of resistome. Significantly, environmental conditions and MGEs highly influenced the composition of resistome in the SI, while bacterial community more associated with resistome in the SD. Additionally, we identified 36 human bacterial pathogens as potential hosts of ARGs, MRGs, and MGEs in wastewater samples. This study provides new insights on the dissemination mechanisms and risk assessment of antimicrobial resistance in the different types of WWTPs.

Application of Decentralized Wastewater Treatment Technology in Rural Domestic Wastewater Treatment

The management of domestic wastewater in rural areas has always been challenging due to characteristics such as the wide distribution and dispersion of rural households. There are numerous domestic sewage discharge methods used in rural areas, and it is difficult to treat the sewage. To address this problem, decentralized wastewater treatment systems (DWTSs) have been installed around the globe to reuse and recycle wastewater for non-potable uses such as firefighting, toilet flushing, and landscape irrigation. This study compares the currently implemented treatment processes by investigating them from the point of view of their performance and their advantages and disadvantages to provide new ideas for the development of rural wastewater treatment technologies. According to conventional treatment technologies including activated sludge (OD, A/O, A/A/O, SBR), biofilm (biofilter, MBBR, biological contact oxidation, biofluidized bed) and biogas digesters, natural biological treatment technologies including artificial wetlands (surface flow, vertical flow, horizontal submerged flow artificial wetlands), soil percolation systems (slow, fast, subsurface percolation and surface diffusion) and stabilization pond technology and combined treatment technologies are categorized and further described.

Start-up phase performance evaluation of a pilot-scale sequential anaerobic-aerobic hybrid algal-bacterial suspended growth reactor for the domestic wastewater treatment

This study evaluated the start-up phase performance of an 80-cubic-meter pilot-scale anaerobic-aerobic hybrid algal-bacterial reactor treating real domestic wastewater operated at 24 h hydraulic retention time. The aerobic chambers of the reactor were inoculated with heterotrophic bacterial biomass and mixed microalgal culture. Blue light-emitting-diode (LED) lights were provided in the aerobic chambers to facilitate algal photosynthesis. The influent chemical oxygen demand (COD), total nitrogen (TN), and phosphorus (P) values were 241 ± 45 mg/L, 26.8 ± 4.2 mg/L, and 6.7 ± 0.9 mg/L, respectively. After thirty days of operation, the effluent COD, TN, and P values were observed to be 26.7 ± 6.5 mg/L, 15.6 ± 0.73 mg/L, and 4.45 ± 0.16 mg/L, respectively. The sludge volume index of the mixed liquor was 43 mL/g, indicating high settleability. During the operation, an increase in the chlorophyll to biomass ratio was observed, which implies that the algal-bacterial symbiosis might have played a role in simultaneous carbon and nitrogen removal from the domestic wastewater.

Innovative Use of Eco-Enzymes for Domestic Wastewater Purification

The rapid pace of urbanization and the resultant increase in waste generation have significantly escalated the challenges associated with managing organic waste. In line with contemporary sustainable practices, it is imperative to recycle and repurpose waste effectively. This study investigates the use of eco-enzyme, an environmentally friendly product derived from fruit and vegetable scraps, along with natural sweeteners, in the treatment of domestic wastewater. The study assessed the impact of eco-enzyme concentrations at 15% and 20% over a five-day period. Results demonstrated that treated wastewater met irrigation standards after the treatment period. Parameters such as acidity, dissolved solids, biochemical oxygen demand, chemical oxygen demand, and microbial counts were analyzed. The 15% eco-enzyme solution reduced biochemical oxygen demand by 90.54% and chemical oxygen demand by 83.33%, while the 20% solution achieved reductions of 94.20% and 86.34%, respectively. Dissolved solids levels were reduced to 412 ppm and 422 ppm for the 15% and 20% solutions, respectively, and microbial counts decreased significantly. However, the study is limited by the short duration of the treatment period and the scope of the parameters analyzed, which may not fully capture the long-term effectiveness and broader environmental impacts of eco-enzyme use. This research underscores the potential of eco-enzyme technology in enhancing wastewater treatment processes, promoting environmental sustainability, and alleviating the burden on waste management systems. The eco-enzyme production process is straightforward and accessible, involving the fermentation of kitchen waste, and can be readily adopted in both urban and rural settings. Further research is recommended to optimize the fermentation process, reduce digestion time, and explore the broader applications of eco-enzymes in fields such as agriculture and domestic cleaning.

Phycoremediation of Domestic Waste Water and Biodiesel Extraction from Fresh-Water Microalgae

ABSTRACT: Microalgae have recently drawn attention as a potential source for the sustainable production of biotechnologically valuable resources and improving the environment in various ways. They are widely distributed and can thrive even under extreme circumstances like high temperatures or high salinity. However, producing microalgae takes a lot of nutrients, which may have an adverse impact on the environment and the economy. The use of wastewater, particularly those from agro-industrial facilities, domestic waste waters, and industrial discharges, which often contain high nutrient concentrations, can serve as an alternative to synthetic culture media. Because the composition of wastewater and usual culture media is relatively similar, wastewater can be utilized to both clean itself and culture microalgae at the same time. Utilizing microalgae as wastewater bioremediation agents can efficiently remove N and P from domestic wastewater, maintain dissolved oxygen concentration, and reduce the various disease-causing pathogens and fecal bacteria that are present in domestic wastewater. The potential of microalgae to be used as a feedstock is increased by their ability to change the composition of their biomass under stress and accumulate lipids or carbohydrates that might be used to produce biodiesel. Methyl or ethyl esters of fatty acids produced from triglycerides by transesterification process by using renewable feedstocks are known as biodiesel. The microalgal biomass is considered as the next generation of feedstock for biofuel production. The Dual function of microalgae in domestic wastewater treatment and biomass growth for biodiesel production is outlined and discussed in detail in this review paper.

Insight into the impact of air flow rate on algal-bacterial granules: Reactor performance, hydrodynamics by Computational Fluid Dynamics (CFD) and microbial community analysis

This study evaluated the impact of air flow rates on nitrogen removal and the formation of algal-bacterial granules in domestic wastewater treatment, revealing that sodium acetate addition and aeration shifted the microbial community composition. Two separate feedings and the addition of external organic carbon significantly enhanced inorganic nitrogen removal efficiency (over 90 %), which might have contributed to the increased microbial diversity and the relative abundance of denitrifiers such as Acinetobacter. This study also demonstrates that the higher air flow rate (0.5 LPM) resulted in higher nitrification rates (up to 6.4 mg N/L/h) and produced smaller and denser granules. The higher air flow rate also led to the increasing relative abundances of nitrogen-related genera (such as Nitrospira) and the decreasing relative abundances of cyanobacteria and Chlorella. Computational Fluid Dynamics (CFD) simulations revealed that mechanical mixing predominantly generated shear force. Increasing the air flow rate from 0.2 LPM to 0.5 LPM only yielded a 12 % increment in the volume-averaged strain rate, suggesting diminishing returns from higher air flow rates in terms of shear force enhancement. Moreover, the decrease in total abundance of grazers and pathogens along with the operation, including Chytridiomycetes, Sessilida, and Operculariidae, might result from the shear force and the decrease of Chlorella spp.. This study underscores the critical roles of aeration and carbon source management in optimizing the performance and microbial ecology of algal-bacterial systems in wastewater treatment while minimizing energy inputs.

Numerical evaluation of vertical and horizontal distances for nitrogen attenuation from Onsite Sewage treatment and disposal systems (OSTDS)

Onsite Sewage Treatment and Disposal Systems (OSTDS) used for domestic wastewater treatment are a source of nitrogen (ammonium and nitrate) contamination to groundwater and surface water. One way to manage the contamination is to establish setback distances for nitrogen attenuation through nitrification and denitrification reactions within the setback distances. Determining the setback distances requires investigating nitrogen attenuation as a function of distance from OSTDS. While field investigations have been conducted, there have been few modeling investigations. Using an ArcGIS-based Nitrogen Load Estimation Toolkit, this study simulates nitrogen attenuation for over 20,000 OSTDS at five study areas across Florida, where a third of households are served by OSTDS. Different from conventional studies that only consider the horizontal distances (between an OSTDS and a surface water body that receives OSTDS effluents), this study also considers the vertical distances (between an OSTDS drainfield and water table beneath the drainfield) to account for the nitrogen reactive transport processes in the vadose zones and groundwater aquifers, making the assessment of nitrogen attenuation more comprehensive. Modeling results yield the following three empirical but quantitative relations: (1) vertical attenuation rate as a function of vertical distance and saturated hydraulic conductivity (Ks) available in the Soil Survey Geographic Database, (2) horizontal attenuation rate as a function of horizontal distance and Ks, (3) total attenuation rate as a multiplication of the vertical and horizontal attenuation rates. These relations can be used to determine nitrogen attenuation within vertical and horizontal distances to OSTDS for practical management of OSTDS nitrogen contamination.

Reuse of plastic waste as bio-carriers for domestic wastewater treatment – An approach towards circular economy

With the rapid growth of economic development, the circular economy has been raised in many internationalenvironmental and socio-economic conferences and forums nowadays. The recycling of plastic waste was oneof those aspects. This paper studied the potential of directly reusing plastic bottle caps as bio-carriers in movingbed bioreactors without further waste processing. As the caps had lower surface areas than the commercial carriers, total bacteria communities on the commercial carriers (K3) were 3-4 times higher than those on the bottle caps at different counting magnitudes. Nevertheless, the bottle caps could accommodate similar nitrogen-based bacteria (ammonia-oxidizing bacteria - AOB and nitrite-oxidizing bacteria - NOB density), which promotes well for the nitrification and denitrification processes. The COD and N-NH4 removal efficiencies were 92% and 86% on average, respectively. The high pollutant removal capacity reveals the very promising potential of bottle caps as bio-carriers for domestic wastewater treatment, promoting waste reduction and treatment expenses and presenting an excellent example of economic circular.

Treatment of Domestic Wastewater Using Membrane Bioreactor (MBR) Pilot Plant: A Case Study of Wastewater from Kklung Hok’s Treatment Pond and The Environmental Research and Training Centre (ERTC), Pathumthani, Thailand

This research performant of Membrane Bioreactor (MBR) pilot plant for treatment of Wastewater from Khlung Hok’s treatment pond volume of 250 liter and The Environmental Research and Training Centre (ERTC) volume of 100 liter, both wastewater was mix on MBR. Aeration was fed at air flow rate 150 l/min over two hours to provide the oxygen for microorganisms. Further, Aeration was fed continuously for 6 hours. sample were collected every one hour. Result found that: the wastewater variation of pH, DO, BOD, COD, NH4+, NO2– concentration of the feed tank from Khlung Hok’s treatment pond were 7.16, 0.60 mg/l, 95mg/l, 157 mg/l, 34.96 ppm and NO2 not found and from ERTC’s wastewater were 6.87, 0.41 mg/l, 93 mg/l, 160 mg/l, 21.23 ppm and 0.043 ppm, respectively. After air flow in MBR over 2 hour the concentration of influent was found 6.64, 0.60 mg/l, 48 mg/l, 105.67 mg/l, 22.30 ppm and 0.031 ppm, respectively. And during the whole process effluent pH concentration were between 6.64-7.46, DO were between 1.11-5.8 mg/l. The removal BOD efficiency were over 89.58% (on 5th hour), COD were over 75.39% (on 4th hour), NH4 were over 53.61% of (on first hour) and were over NO2 48.71% of (on 2nd hour), respectively. Result indicated that effective removal BOD, COD, NH4+ and NO2– by MBR could be achieved and increased in scale for use in the fieldwork or the treatment of wastewater in the environment.