Domestic Wastewater Treatment Facilities Research Articles

Performance Assessment of Rural Decentralized Domestic Wastewater Treatment Facilities in Foshan, China

Rural decentralized domestic wastewater treatment (DDWT) facilities, as an alternative to centralized sewage treatment plants, have been rapidly developed in rural areas worldwide. However, the lack of performance evaluations and operational status assessments of these facilities poses a significant obstacle to advancements in rural domestic wastewater treatment strategies. In the present study, 30 rural DDWT facilities with AO (anoxic/oxic) and AAO (anaerobic/anoxic/oxic) processes were investigated. The results revealed that only two facilities reached the first A-grade discharge standards of China, and twelve facilities met the first B-grade discharge standards for all ten wastewater quality indicators. Low standard-achieving ratios for biochemical oxygen demand (BOD5) (63.3%), total nitrogen (TN) (60.0%), ammonia nitrogen (NH3-N) (63.3%), total phosphorus (TP) (30.0%), suspended solids (SS) (46.7%), and fecal coliforms (FC) (26.7%) were calculated. Thus, it is essential to improve the treatment efficiency for BOD5, TN, NH3-N, TP, SS, and FC for rural wastewater treatment facilities. In addition, the AAO process had a median weighted average removal efficiency of 82.02%, which was better than that of the AO process (72.48%). Minor equipment failure rates, i.e., less than 20%, did not affect the operation of the rural DDWT facilities, since most equipment in the DDWT facilities was backed up. Notably, problems in several areas, e.g., process design, equipment selection, construction, and especially operations, influencing treatment performance should be investigated and proactively addressed. These findings provide specific suggestions for improvements that could benefit the long-term operation and management of rural DDWT facilities.

Application of the Monte-Carlo Method to Assess the Operational Reliability of a Household-Constructed Wetland with Vertical Flow: A Case Study in Poland

The objective of this study was to model the operation of a vertical-flow constructed wetland (VF-CW) for domestic wastewater, using Monte-Carlo simulations and selected probability distributions of various random variables. The analysis was based on collected wastewater quality data, including the values of the pollutant indicators BOD5 (biochemical oxygen demand), CODCr (chemical oxygen demand), and TSS (total suspended solids), in the 2017–2020 period. Anderson–Darling (A–D) statistics were applied to assess the fit of the theoretical distributions to the empirical distributions of the random variables under study. The selection of the best-fitting statistical distributions was determined using the percentage deviation (PBIAS) criterion. Based on the analyses that were performed, the best-fitting statistical distributions for the pollution indicators of the raw wastewater were the generalised extreme value distribution for BOD5, the Gaussian distribution for CODCr, and the log-normal distribution for TSS. For treated effluent, the log-normal distribution was the best fit for BOD5 and CODCr; the semi-normal distribution, for TSS. The new data generated using the Monte-Carlo method allowed the reliability of the VF-CW operation to be assessed by determining the reliability indices, i.e., the average efficiency of the removal of pollutants (η), the technological efficiency index (R), the reliability index (CR), and the risk index of the negative control of the sewage treatment plant operation (Re). The obtained results indicate that only in the case of CODCr, the analysed treatment facility may fail to meet the requirements related to the reduction of organic pollutants to the required level, which is evidenced by the values of the indicators CR = 1.10, R = 0.49, and η = 0.82. In addition, the risk index of the negative operation of the facility (Re) assumes a value of 1, which indicates that during the period of its operation, the VF-CW system will not operate with the required efficiency in relation to this indicator. The novelty of this work is the implementation of the indicated mathematical simulation methods for analysing the reliability of the operation of the domestic wastewater treatment facility.

Organophosphate esters in rural wastewater along the Yangtze river Basin: Occurrence, removal efficiency and environmental implications

Organophosphate esters (OPEs) discharged from rural domestic wastewater were one of the important sources of OPEs in receiving water bodies, which has posed a potential threat to the ecological environment. However, very little information on the characteristics of OPEs in the rural domestic wastewater is available. Herein, the occurrence, removal efficiency and environmental implication of OPEs in rural domestic wastewater treatment facilities (RD-WWTFs) along the Yangtze River Basin were investigated. Results indicated that the median concentrations of ΣAlkyl-OPEs, ΣHalogenated-OPEs, ΣAryl-OPEs and the total OPE (ΣOPEs) in influents were 28.28, 99.25, 10.22 and 136.84 ng/L, while the median concentrations of them in effluents were 25.80, 141.86, 7.98 and 173.31 ng/L, respectively. Undoubtedly, halogenated OPEs were the most abundant in both influent and effluent, followed by alkyl and aryl OPEs, and they accounted for average proportions of 69.50%, 19.96%and 10.54% for influents, and 78.16%, 16.14%and 5.71% for effluents, respectively. Specifically, tris(2-chloroisopropyl) phosphate (TCPP, median: 55.17 ng/L in influents and 85.75 ng/L in effluents) was the dominant contributor to the ΣOPEs concentrations with average proportions of 37.75% and 47.33% for influents and effluents, respectively. Moreover, the concentration ranks for most OPEs except for aryl OPEs from high to low were upper reaches > lower reaches > middle reaches. However, negative values of tris(2-chloroethyl)phosphate (TCEP, −32.4%), TCPP (−55.4%) and tris(1,3-dichloroisopropyl) phosphate (TDCPP, −26.3%) were observed. The removal rates of alkyl OPEs (10–20%) and aryl OPEs (20–30%) were also not sufficient. Ecological risk values of ΣOPEs showed that there were 2.44% of high risk, 31.7% of moderate risk and 41.5% of low risk for effluents; while 0.00%, 48.8% and 46.3% were exhibited in high, moderate and low risk for influents, indicating that very slight reduction in risk was achieved by the RD-WWTFs.

Analysis on the Utilization of Renewable Energy for Carbon Neutralization in Sewage Treatment Facilities

Domestic wastewater treatment facilities(WTF) in Korea consume a lot of energy and generate greenhouse gases in the process of treating contaminated sewage. In response to climate change and the government's carbon neutrality, measures for energy reduction in WTF is an important issue along with water quality management, and simultaneously, diversification of renewable energy based on treatment facilities is essential. The energy independence and renewable energy utilization by facility capacity were analyzed based on sewage statistics (2019) and operation data of the National Sewage Information System. The amount of energy consumed by WTF was analyzed to be 83.6 million TOE, and the renewable energy produced was 10.8 million TOE. In consequence of analysis, the energy independence of domestic WTF in Korea was 12.9%. Among renewable energy, the contribution of biogas was the highest at 83.6%, but the current status of energy independence is somewhat insufficient to energy independence plan of WTF, requiring support for alternatives and policies to produce and secure additional renewable energy. In order to increase and diversify the use of renewable energy, the integrated digestion biogas of organic waste resources, the use of cooling and heating energy based on sewage heat, and the development of salinity gradient power generation were reviewed. Based on this, it was intended to contribute to the preparation of measures to achieve carbon neutrality in sewage treatment facilities.

Treatment of High Nutrient-Loaded Wastewater in a Constructed Floating Wetland with Different Configurations: Role of Lantana Biochar Addition

Constructed wetlands (CW) with carbon stock in substrate matrix show high efficiency in wastewater nutrient removals. In this study, five batch-scale CW setups with varying Lantana weed biochar (BC) doses (5, 10, and 15%) in substrate matrix were established and changes in high nutrient-loaded wastewater parameters, ammonium N (NH4+-N), chemical oxygen demand (COD), nitrate (NO3-N), sulfate (SO4−2), and phosphate (PO4−3), were monitored for 240 h hydraulic retention time (HRT). BC amount directly affected the removal mechanism of CWs and a significant reduction in COD (>92.71%) was recorded. CW setup with a 15% BC dose showed the maximum removal of PO4−3 (79.06%), NH4+-N (78.79%), SO4−2 (67.93%), and NO3-N (77.42%) from wastewater. The theory of BC facilitated physical removal, microbial facilitation, and chemical kinetics improvements are proposed for better removal of wastewater nutrients in studied CWs. Research results could be utilized to design a low-cost domestic wastewater treatment facility using BC for rural areas under a decentralized water treatment program.

Insights into the occurrence, elimination efficiency and ecological risk of antibiotics in rural domestic wastewater treatment facilities along the Yangtze River Basin, China.

China is embarking on the treatment of rural domestic wastewater, but little information on the characteristics of antibiotics in the rural domestic wastewater is available. As one of the most important new-emerging pollutants, antibiotic has been explicitly proposed to be controlled and treated since the fifth plenary session of the 19th Central Committee of the Communist Party of China. Thus, the occurrence, elimination efficiency and ecological risk of antibiotics, as well as conventional wastewater quality parameters were investigated in influents and effluents from 41 rural domestic wastewater treatment facilities (RD-WWTFs) along the Yangtze River Basin. Results showed that elimination efficiencies of routinely monitored conventional pollutants in 33 RD-WWTFs (accounting for 80.5%) were effective based on conventional wastewater quality parameters. Of 39 target antibiotics selected, 26 ones were detected in the influents and effluents with a detection frequency (DF) between 2.4% and 100%. No significant decrease of antibiotics was observed in the effluents compared with that in the influents except chlortetracyclin (CTE) and tetracycline (TCs). The composition characteristics of antibiotics showed regional differences. Among the investigated antibiotics, ofloxacin (OFX), doxycycline (DOX), roxithromycin (ROX) and lincomycin (LIN) were the predominant, totally accounted for a median percentage of more than 60% of ΣAB concentrations in both influents and effluents. Ecological risk values of ΣABs showed that 11 effluents presented high risks (26.8%), 18 ones had moderate risks (43.9%), and the rest 12 ones showed low risks (29.3%). Moreover, oxytetracycline (OXY), norfloxacin (NOR), LIN and ROX was the dominant contributors to the ecological risk values. Overall, the elimination effect of antibiotics was limited in RD-WWTFs along the Yangtze River Basin, which was likely to pose potential adverse impacts on aquatic ecosystems.

Application of an Anaerobic–Anoxic–Oxic–Oxic (AAO/O) Model to the Treatment of Real Domestic Wastewater

Untreated or inadequately treated domestic wastewater has adversely affected the aquatic environment and public health in many cities in Vietnam. A conventional anaerobic–anoxic–oxic (AAO) process is recognized as an easy-to-handle approach that constrains chemical use during the procedure. Herein, we improve an AAO system by adding more oxic orders in association with a biological membrane in order to increase the hydraulic retention time (HRT) of the oxic zone in the system. The investigated system was applied to the treatment of real domestic wastewater during 168 days of operation. The performance of the system reached a stable state after 60 days of operation. The removal efficiency of total nitrogen (TN), total phosphorus (TP), total suspended solids (TSS), biological oxygen demand (BOD5), and chemical oxygen demand (COD) was found to be 93.6 ± 3.0%, 91.9 ± 3.5%, 88.6 ± 1.2%, 82.6 ± 1.4%, and 71.8 ± 0.7%, respectively. After the operation process, the TN, TP, and TSS contents in the wastewater effluents met the A level in accordance with the QCVN 14-MT:2015/BTNMT regulation, and the effluents of COD and BOD5 almost satisfied the requirement, with only some points being slightly higher than the limit values. The obtained data revealed that the AAO/O system was capable of treating domestic wastewater in small and medium-sized domestic wastewater treatment facilities.

FEASIBILITY STUDY OF COMMUNAL DOMESTIC WASTEWATER TREATMENT PLANT IN SEKANAK AREA, PALEMBANG CITY

Pollution, whether in the form of domestic wastewater or solid waste generated by daily activity, is to blame for this. In Indonesia, most domestic wastewater treatment still takes place locally, on-site, for instance, using septic tanks. The septic tank essentially only serves to precipitate the sludge content in home waste water, allowing it to contaminate soil, ground water, and eventually surface water bodies. There have been several domestic wastewater treatment facilities (WWTP) in Palembang City throughout the previous five years, both on a local and regional level, all of which are still in use. One of the city of Palembang's current WWTP facilities, Sekanak's WWTP is located not far from the river's edge. This WWTP was constructed to deal with the liquid waste generated by households in order to prevent direct pollution of the Sekanak River. This study used a quantitative descriptive method to accurately explain and represent the field circumstances based on the quantitative data that was collected. Installing an equalization tank in accordance with the input discharge to balance out the discharge of the collection tank and the discharge of the incoming wastewater will improve the old Sekanak WWTP. This method can be used to lessen and prevent water quality pollution from WWTP outputs.

Insights into the Occurrence, Elimination Efficiency and Ecological Risk of Antibiotics in Rural Domestic Wastewater Treatment Facilities Along the Yangtze River, China

Insights into the Occurrence, Elimination Efficiency and Ecological Risk of Antibiotics in Rural Domestic Wastewater Treatment Facilities Along the Yangtze River, China

PLANNING OF DOMESTIC WASTEWATER FACILITIES (CASE STUDY: BABAKAN VILLAGE, CIPARAY DISTRICT, BANDUNG REGENCY)

Babakan Village has a problem that there is still a lack of facilities for wastewater. This condition can be seen from the access to the toilets of 2436 households; only around 1506 families have access to family/ shared latrines and 625 households that meet technical requirements. For this reason, this plan is useful for increasing access and meeting community needs for domestic wastewater treatment facilities in the study area. This planning stage begins with a survey and sanitation inspection to determine 3 priority areas for handling. Determinants of this priority area use the method of scoring and weighting the risk. The weighting results put sub village 02 with a score of 2.3, sub village 05 with a score of 2.25, and RW 10 with a risk value of 2 as the priority area for planning handlers. Primary data collected will be used as a consideration for determining the technology to be applied. The technology chosen for processing is the communal septic tank for people who do not have treatment. In contrast, for the washing bath, toilet with a biofilter unit for people who do not have wastewater infrastructure.

Occurrence of Antibiotics, Antibiotic Resistance Genes and Viral Genomes in Wastewater Effluents and Their Treatment by a Pilot Scale Nanofiltration Unit.

Broad-spectrum fluoroquinolone antibiotics (ciprofloxacin and levofloxacin), carbapenem and fluoroquinolone resistance genes, as well as viral genomes, were detected in grab samples of wastewater effluents. Passive samplers, which are simpler and easier to use and provide information about the concentrations and combination of contaminants present in a certain fluid matrix over time, proved to be extremely promising devices to monitor the presence of the target antibiotics in wastewater effluents. Nanofiltration was tested with a pilot-scale unit installed at a domestic wastewater treatment facility, using a Desal 5DK membrane operated at a constant transmembrane pressure of 6 bar and 70% recovery rate. In a 24 h experimental assay, the variation of the membrane permeance was low (6.3%). High rejections of the target contaminants from the wastewater effluent were obtained by the pilot-scale treatment. Hence, nanofiltration using the Desal 5DK membrane is considered to be a promising treatment to cope with chemical and biological contaminants present in wastewater effluents.

Distribution of Antibiotic Concentration in Domestic Wastewater Treatment Facilities in Villages and Towns

Antibiotics discharged into the environment cause increased environmental resistance. Four types of antibiotics (quinolones, tetracyclines, macrolides, and β-lactams) were selected for this study. In a comparison with the municipal wastewater plant, the concentration and removal of antibiotics in influent and effluent of domestic wastewater treatment facilities of different scales in villages and towns was investigated using high-performance liquid chromatography (HPLC) and tandem mass spectrometry (MS). The results showed that the highest amount of ofloxacin in rural wastewater treatment facilities reached 32663.5 ng·L-1. Due to the different situations of influent fluctuation, discharge requirements, and management between urban and rural wastewater plants, only 33% of the rural domestic wastewater facilities detected an antibiotics removal rate of more than 60%. The effective removal of some antibiotics can be achieved when the rural domestic wastewater treatment facilities maintain the standard discharge of conventional pollutants.

Domestic wastewater treatment facilities of small towns

The urgency of biogenic elements removal is caused by ever-increasing degree of eutrophication of surface water, which increases the mass of phytoplankton, water turbidity, oxygen concentration in the upper water layers and reduces in thickness. To remove biogenic elements from wastewater, a method based on the use of bioreagents – chemical compounds of trace elements based on biologically active copolymers – is successfully implemented.This article presents the results of a survey of existing facilities of a biological wastewater treatment plant in a small locality. The survey revealed low efficiency of processes at the stage of biological purification, primarily with regard to the speed of biochemical processes, namely, the time-limited ability of dephosphotation, and as a result, a small withdrawal of total phosphorus at the stage of biological purification directly by active sludge microorganisms. In order to intensify the work of biological wastewater treatment facilities, an experiment was conducted on the use of bioreactor in real operation at these treatment facilities.

Characteristics and removal of microplastics in rural domestic wastewater treatment facilities of China

The environment of the countryside is different from that of the city. Studying the abundance, characteristics, and removal of microplastics (MPs) in rural domestic wastewater treatment facilities (RD-WWTFs) is of great significance for understanding the impacts of human activities on the environment of the countryside. Therefore, we studied five such facilities in the Hangzhou region of China. The abundance of MPs in the influent was 430–2154 items/m3. Micro-Raman spectroscopic analysis indicates that the main type of polymer in the influent is polypropylene (PP, 54.6%), followed by polystyrene (PS, 29.7%) and polyethylene terephthalate (PET, 9.7%). The color of MPs is mainly white and clear (62.9%), red (13.3%) and gray (12.0%). Our results show that fragments (71.3%) are the dominant shape of MPs, followed by fibers (21.5%). The characteristics of MPs, such as sizes, shapes, and types, along with the treatment process, affect the removal of MPs in RD-WWTFs. Large MPs are easily removed by anaerobic processes, while small MPs are better removed by anaerobic/anoxic/oxic processes. Fibrous MPs are more difficult to be removed than the fragmented ones. Constructed wetlands play an important role in the removal of MPs.

Study on the evaluation method of operation performance for rural domestic wastewater treatment facilities

Rural domestic wastewater treatment has become one of the key and main battlefields of China’s sewage treatment industry, the operation performance of rural domestic wastewater treatment facilities is directly related to the realization of rural environment comprehensive renovation and rural revitalization strategic planning objectives. This paper expounds the present situation and existing problems of the operation of rural domestic wastewater treatment facilities in China, and the necessity of carrying out the research on the evaluation method of the operation performance of rural domestic wastewater treatment facilities, and rural domestic wastewater treatment facilities Operation Evaluation Index System Construction, evaluation index calculation method, scoring standards and evaluation methods. It is expected to promote the operation reliability and effectiveness of rural domestic wastewater treatment facilities in China through the use of evaluation methods of the operation effectiveness of rural domestic wastewater treatment facilities.

Visual Improvement of Slum Areas to Accelerate Universal Access to Domestic Wastewater Treatment (Case study of Yogyakarta, Semarang and Manado)

Lack of sanitation access is among characteristics of urban slums; therefore strategies to improve sanitation are needed. One possible strategy is to improve visual appearance of slum buildings by painting walls with colours. Other than improving community awareness to maintain cleanliness, this approach can provide economic benefit for the residents, as it creates tourism activities. This paper observes visual improvement of slum areas; besides ability to accelerate access to domestic wastewater treatment is compared. This study observe domestic wastewater treatment facilities after visual improvement carried out in three different slum locations in Indonesia. They are Kampung Code in Yogyakarta, Kampung Wonosari in Semarang and Kampung Sindulang in Manado. Initiation of coloring project of the three urban area is different. Community and private sector initiated Kampung Code painting project, while the local government initiated similar project of Kampung Wonosari and Kampung Sindulang. Observation was performed by distributing questionnaires to residents of the slum areas and path analysis executed afterward. A sample size of 64, 270 and 102 were taken from Kampung Code, Kampung Wonosari and Kampung Sindulang respectively, with 5% margin of error. Wastewater management behaviour was measured based on level of community intention to manage sanitation. Intention is derived from three different independent variables: attitude, subjective norms and perceived behaviour control. Significant effects of the colouring project to improve community awareness towards the importance of domestic wastewater treatment facilities was observed in all slums.

Kinetics of nutrient removal in an on-site domestic wastewater treatment facility

Domestic wastewater from office building has not been maintained well especially in the areas where the sewerage system is unavailable. The aims of this research were to investigate the performance and kinetics of nutrient removal in an on-site domestic wastewater treatment facility which consists of anaerobic and aerobic systems for treating wastewater from office building. The experimental data obtained from the variations of COD:N:P ratio 250:28:2.5, 350:38:2.9, 450:47:3.3, and 600:60:3.7 with three different HRT 48h, 24h, and 12h. A One-way ANOVA was performed to investigate the effects of HRT and initial concentration of TN and TP on the performance of nutrient removal. In order to obtain the kinetic coefficients, First Order, Second Order and Stover-Kincannon Models were employed. The results showed that maximum TN and TP removal efficiency were 56% and 86%, respectively. The results of one-way ANOVA showed that HRT and initial concentration of TN and TP gave the significant effects on nutrient removal (p < 0.05). Second Order and Stover-Kincannon Models were found to be more appropriate models for prediction of TN removal in this facility. Controlling HRT and C: N: P ratio may keep good performance of nutrient removal in this facility.

Fatty acids from high rate algal pond’s microalgal biomass and osmotic stress effects

The extraction of oil from a wild microalgae biomass collected from a domestic wastewater treatment facility’s high rate algal pond (HRAP) was investigated. An experiment plan was used to determine the most efficient extraction method, the optimal temperature, time and solvent system based on total lipids yield. Microwave-assisted extraction was the most efficient method whether in n-hexane or in a mixture of chloroform/methanol compared to Soxhlet, homogenization, and ultrasounds assisted extractions. This same wild biomass was cultivated in a photobioreactor (PBR) and the effect of osmotic stress was studied. The lipids extraction yield after 3days of stress increased by more than four folds without any significant loss of biomass, however, the quality of extracted total lipids in terms of saturated, monounsaturated and polyunsaturated fatty acids was not affected by salinity change in the culture medium.

Sludge settling prediction in sequencing batch reactor plants

Sequencing batch reactors are widely applied in domestic and industrial wastewater treatment facilities. Their use relies on the possibility of separating the sludges from the liquid phase by settling in an acceptable time. The aim of this work has been to develop a simple method for predicting the settling curve in pilot and industrial plants from the results obtained at laboratory scale. For this purpose, jar test settling experiments were carried out in a one-litre cylinder tube together with sludge volume index and volatile suspended solids determinations. For sludges with low content of filamentous microorganisms, a simple method consistent in obtaining settling velocities as a function of the relative height of the sludge blanket was developed. Additionally, a more general correlation between the sludge volume index and the ratio (settling velocities at pilot plant scale)/(settling velocities in the laboratory tests) was obtained. Having estimated the settling velocity, the necessary settling time may be calculated and the industrial equipment units can be dimensioned. The method yields good results for the values of sludge volume index between 30 and 240 mL/g.

Florida Biosolids: Rules for Biosolids Classes

Biosolids are the liquid, semisolid, and solid fractions of the treated waste stream from a domestic waste water treatment facility. This 5-page fact sheet, part of the Florida Biosolids series, provides an overview of biosolids, biosolids classes, pathogen reduction, vector attraction reduction, and metal contaminants, and also discusses the purpose, applicability, and history of Chapter 62-640, Florida Administrative Code. Written by John Hallas, Ann C. Wilkie, and Cheryl L. Mackowiak, and published by the UF Department of Soil and Water Science, December 2015. SL422/SS635: Florida Biosolids: Rules for Biosolids Classes (ufl.edu)