Capacity Of Wastewater Treatment Plants Research Articles

Lessons in Legacies: Treatment Plant Expansion Under the Clean Water Act

The US Clean Water Act of 1972 required cities to build secondary wastewater treatment plant capacity to improve the environment and protect public health. The expansion of the Southeast Pollution Control Plant in San Francisco’s Bayview-Hunters Point, a historically Black neighborhood, illustrates how planners employed rational-comprehensive approaches as the bases for their decision-making, worsening the community’s environmental burdens. This occurred even as the community used recently adopted environmental policy frameworks to mitigate the plant’s consequences. The Clean Water Act should be evaluated on clean water objectives and in terms of how communities were harmed to achieve these environmental goals.

Is Africa Ready to Use Phycoremediation to Treat Domestic Wastewater as an Alternative Natural Base Solution? A Case Study

This review outlines the potential of phycoremediation as a natural, cost-effective solution for domestic wastewater treatment in Africa, particularly focusing on its application in less densely populated and rural areas. The urgency of improving sanitation access, a key objective in both the Millennium Development Goals (2000–2015) and the Sustainable Development Goals (2015–2030), is underscored by the fact that half of Africa’s population suffers from diseases linked to inadequate water and sanitation facilities. South Africa, a focal point of this study, faces significant challenges in wastewater management. These include the limited capacity of wastewater treatment plants to handle the burgeoning wastewater volumes due to population growth, unregulated discharges causing fluctuating pollution levels, and high operational costs leading to improper sludge disposal and odor issues. Compounding these problems are frequent power outages, financial constraints impacting wastewater treatment plant operations and maintenance across Africa, and a lack of skilled personnel to manage these facilities.

Performance and life cycle assessment of moving-bed biofilm and integrated fixed-film reactors to upgrade activated sludge systems

Upgrading the capacity of existing wastewater treatment plants (WWTPs) is hindered by the limited space for extension. This matter is particularly crucial in developing countries where dense urban areas experience unexpectedly growing populations. Herein, we study the capacity upgrading of a WWTP working by a conventional activated sludge (CAS) system from 180,000 m3/d to 240,000 and 300,000 m3/d. The WWTP case study focuses on a large plant in Mansoura, Egypt, requiring capacity upgrades to accommodate population growth. For this purpose, we used mathematical modeling to simulate current and suggested WWTP designs. Moving bed biofilm reactor (MBBR) and integrated fixed film-activated sludge (IFAS) systems were designed to increase the WWTP capacity to 240,000 and 300,000 m3/d by the addition of plastic biofilm carrier to 25% and 50% of the aeration basins, respectively. IFAS outperformed conventional and MBBR systems in terms of BOD, COD, TSS, NH4, TP, and PO4, in addition to increased capacity. We moreover used life cycle assessment (LCA) to comprehend the environmental favorability of upgrading scenarios. The most affected environmental categories are global warming and eutrophication due to the operation stage (especially electricity). Global warming potential for CAS, MBBR, and IFAS (300,000 m3/d) are 2.19, 1.69, and 1.73 kg CO2 eq respectively. Eutrophication potential for CAS, MBBR, and IFAS (300,000 m3/d) are 0.0025, 0.0022, and 0.0017 kg PO4- eq respectively. We also estimated the amortization and running costs for various upgrading scenarios, providing an integrated analysis for decision-making purposes.

Linking elevated rainfall with sewage discharge volume

Abstract The intricate hydrological processes elucidating the interplay between rainfall and flow manifest through rainwater's traversal along diverse routes, encompassing surface runoff and subsurface flow. While the foundational association between these entities is discernible, the convoluted intricacies characterizing this correlation defy straightforward comprehension. Examining the data between 2019 and 2022, the average daily sewage outflow was 12,518 m3/d, with occasional peaks of up to 50,440 m3/d. The wastewater treatment plant's capacity of 35,000 m3/d was usually not exceeded. Overall, average daily sewage outflows varied between 11,716 m3/d and 13,969 m3/d during the studied period. Comprehending this interrelationship holds pivotal significance for the optimization of water-resource-management strategies. A moderate correlation (r = 0.42) between daily rainfall levels and sewage discharge was found in the dataset covering 2018–2023. When categorizing daily rainfall into groups labelled “A” through “G” and comparing them to sewage flows, a pattern emerged: Rain-free days in group “A” had the lowest average sewage flow (10,996 m3/d), while heavy rain days in group “G”, had the highest average flow (22,112 m3/d). This observation underscores a significant correlation between intensified rainfall and increased volume of sewage discharge. Through a comprehensive analysis of factors such as sewage composition, meteorological dynamics and chronological sequences, we will gain an enhanced ability to prognosticate and govern sewage systems. The significance of this is heightened within the context of evolving climatic dynamics.

Concentration of the main persistent organic pollutants in sewage sludge in relation to wastewater treatment plant parameters and sludge stabilisation

Concentration of 16 polycyclic aromatic hydrocarbons (PAHs), 7 polychlorinated biphenyls (PCBs), and 11 organochlorine pesticides (OCPs) in sewage sludge from 40 wastewater treatment plants (WWTPs) was investigated. Relationship between pollutant sludge contents, main WWTP parameters and type of sludge stabilisation was carefully evaluated. Average load of PAHs, PCBs, and OCPs in different sludges from Czech Republic was 3096, 95.7 and 76.1 μg/kg dry weight, respectively. There were moderate/strong correlations among the individual tested pollutants in sludge (r = 0.40–0.76). Relationship between total pollutant contents in sludge, common WWTP parameters and sludge stabilisation was not evident. Only individual pollutants such anthracene and PCB 52 correlated significantly (P < 0.05) with biochemical oxygen demand (r = −0.35) and chemical oxygen demand removal efficiencies (r = −0.35), suggesting recalcitrance to degradation during wastewater treatment. When sorted according to the design capacity, a linear correlation between WWTP size and pollutant contents in sludge was evident with growing WWTP capacity. Our study indicated that WWTPs with anaerobic digestion are prone to accumulate a statistically higher content of PAHs and PCBs (P < 0.05) in digested sludges compared to aerobically digested ones. The influence of anaerobic digestion temperature of treated sludge on tested pollutants was not evident.

Effect of Saline Sludge on Anaerobic Digestion of Kitchen Waste for Methane Generation: Modeling and Fertilizer Recovery

AbstractA comparative study of methane recovery by co‐digesting kitchen waste and saline sewage sludge is performed to evaluate its feasibility for waste minimization. The experiment is performed at 37 °C having a mixing speed of 100 rpm and pH of 6.49–7.5 in anaerobic mixed batch reactors. The higher salinity level of the saline sewage sludge reduces the degradation rate of kitchen waste causing an enhancement in soluble chemical oxygen demand by 133% compared with 280% when co‐digesting with the non‐saline sample. The inhibitory behavior is in line with the low volatile solid elimination efficiency of 31% of saline against 55% of non‐saline sludge. The Gompertz modeling, based on the outcomes, fits the cumulative methane generation trends quite well, with a strong correlation coefficient (&gt;0.994). Besides, use of the non‐saline sludge results in three times more methane production than the saline sample digestion. Sludge recovery is 0.07 m3 sludge m−3 wastewater, and water recovery is 0.84 m3 m−3 wastewater. The liquid produced from the fermentation of the slurry can be used for irrigation as well as fertilization. Kitchen waste co‐digestion with both sludge samples has been proven to be a practical method for exploiting the extra digestion capacity of wastewater treatment plants currently in operation, but it is more practical for non‐saline sludge.

Bacterial Community Structure and Antibiotic Resistance Gene Changes in IFAS+Magnetic Coagulation Process Wastewater Treatment Plant in Cold Regions

The main objective of this study was to explore the changes in bacterial communities and antibiotic resistance genes (ARGs) in an integrated fixed-film activated sludge (IFAS)+magnetic coagulation process wastewater treatment plant (WWTP) in Xinjiang. The bacterial communities and ARGs in the influent, suspended activated sludge, attached biofilm, and effluent were studied using 16S rRNA gene sequencing and metagenomic sequencing. The results showed that the average relative abundances of Chloroflexi and Nitrospirae in activated sludge were 3.50% and 0.03%, respectively, and their relative abundances in biofilm reached 10.02% and 2.12%, respectively. The average removal rates of NH4+-N and TN increased from 91.89% and 66.76% to 97.71% and 91.90% after the reformation of this wastewater treatment plant, respectively, indicating that IFAS enhanced the biological nitrogen removal capacity of wastewater treatment plants in cold regions. The average relative abundances of Ferruginibacter and Rhodoferax related to iron redox in the biological treatment section were 5.24% and 3.72%, respectively, and the relative abundance of Rhodoferax in effluent reached 9.48%, indicating that the magnetic powder had an impact on the bacterial community. The IFAS wastewater treatment plant had an obvious removal effect on ARGs, and the relative abundance of ARGs decreased from 191.08×10-3‰ in the influent to 32.58×10-3‰ in the effluent. The relative abundance of ARGs in activated sludge was 63.25×10-3‰-72.38×10-3‰, which was significantly higher than 41.31×10-3‰ in biofilm. However, the relative abundances of dominant subtypes of ARGs such as sul2, floR, and rpoB2 in biofilm were 5.77×10-3‰, 2.52×10-3‰, and 2.03×10-3‰, respectively, which were higher than the 3.15×10-3‰-3.57×10-3‰, 1.73×10-3‰-2.24×10-3‰, and 1.28×10-3‰-1.76×10-3‰ in activated sludge. The network analysis indicated that Caldilineaceae_norank and Trichococcus were respectively positively correlated with sul2 and floR. These results can provide theoretical reference for the optimal operation and ARGs control of WWTPs in cold regions.

High concentration powder carrier bio-fluidized bed process: A new perspective for domestic wastewater treatment

The nitrogen removal mechanism of the high concentration powder carrier bio-fluidized bed (HPB) process was investigated with actual domestic wastewater. The micron-size (10–70 μm) powder carriers were diatomite and Fe–C. Results showed diatomite enriched the relative abundances of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, accordingly increasing the rate of nitrification. Even a 100% increase of genes associated with the ammonia oxidation was achieved. Fe–C enhanced the rate of substrate utilization mainly by increasing the activity of the electron transfer system. Hydrocyclone separator, as a key device of HPB, was able to recover the carriers with high efficiency (recovery efficiency of 72.66 ─ 82.50% after 75 days), thus, indirectly improving the functionality of the carriers. Furthermore, it could renew the surface of microbial aggregations, consequently improving the adsorption capacity to substrates. HPB could provide the feasibility of shortening the hydraulic retention time and expanding the capacity of wastewater treatment plants.

The structure of microbial communities of activated sludge of large-scale wastewater treatment plants in the city of Moscow

Microbial communities in wastewater treatment plants (WWTPs) play a key role in water purification. Microbial communities of activated sludge (AS) vary extensively based on plant operating technology, influent characteristics and WWTP capacity. In this study we performed 16S rRNA gene profiling of AS at nine large-scale WWTPs responsible for the treatment of municipal sewage from the city of Moscow, Russia. Two plants employed conventional aerobic process, one plant—nitrification/denitrification technology, and six plants were operated with the University of Cape Town (UCT) anaerobic/anoxic/oxic process. Microbial communities were impacted by the technology and dominated by the Proteobacteria, Bacteroidota and Actinobacteriota. WWTPs employing the UCT process enabled efficient removal of not only organic matter, but also nitrogen and phosphorus, consistently with the high content of ammonia-oxidizing Nitrosomonas sp. and phosphate-accumulating bacteria. The latter group was represented by Candidatus Accumulibacter, Tetrasphaera sp. and denitrifiers. Co-occurrence network analysis provided information on key hub microorganisms in AS, which may be targeted for manipulating the AS stability and performance. Comparison of AS communities from WWTPs in Moscow and worldwide revealed that Moscow samples clustered together indicating that influent characteristics, related to social, cultural and environmental factors, could be more important than a plant operating technology.

Exceedance probability assessment of bathing water quality standards in lake Van based on a geostatistical analysis

Monitoring bathing water quality (BWQ) is highly important in Turkey both for public health issues and tourism income. Lake Van is one of the largest lakes of Turkey and serves as one of the most important tourist attractions in the eastern part of Turkey. This study aims to assess critical bathing sites in Lake Van by using historical BWQ data that was collected twice a month during the swimming season from June 15 to August 31, between the years 2010 and 2020. To avoid public health hazards, it is very important to determine the spatial dimension of inland water pollution and provide visual tools for its presentation. Geostatistical data analysis and the determination of critical locations have been done by a spatial interpolation method, named Probability Kriging (PK) using Geographic Information System (GIS) based software ArcMap 10. Probability maps for exceeding the threshold values identified for the two microbiological water quality parameters of Escherichia coli and intestinal enterococci (IE) were generated, and used for the identification of four critical regions: İskele (4), west side of Gevaş (1), Edremit (3) and Muradiye/Erciş (7). Insufficient wastewater treatment plant capacity serving to high population in these regions may indicate the most pressing issues disturbing the BWQ.

Mapping multiple water pollutants across China using the grey water footprint

The primary pollutants and pollution levels of surface water present spatial and temporal changes. This study quantified the grey water footprint (GWF) and surface water pollution level (WPL) in China from 2003 to 2018 based on four pollutants: chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total nitrogen (TN) and total phosphorus (TP). Additionally, the spatiotemporal distribution of the primary water pollutant (PWP) and driving forces of the GWF were analyzed based on the WPLs and the logarithmic mean Divisia index (LMDI) decomposition method. The results showed that the GWF in China decreased by 13% from 2003 to 2018 and the WPL decreased from 1.11 in 2003 to 0.94 in 2018. An analysis of regional GWFs with multiple pollutants could prevent the underestimation of GWFs and WPLs caused by changes in the PWPs. The GWF spatial distribution was high in the southeast and low in the northwest, while the provinces with larger WPLs were mainly concentrated in northern China. The PWP changed from COD to TN in 2007 because of the increase in nitrogen application in China, the low TN reduction capacity of wastewater treatment plants and the improved comprehensive utilization rate of livestock and poultry manure. The driving force analysis results showed that water efficiency and technological and industrial structural effects promoted the reduced GWF. Our research conclusions and policy suggestions could provide references for reducing the GWF and improving the water quality in China.

Supersaturated-oxygen aeration effects on a high-loaded membrane bioreactor (HL-MBR): Biological performance and microbial population dynamics

Conventional diffused aeration systems (such as fine-bubble diffusers) exhibit a poor oxygen transfer in wastewater treatment plants (WWTPs), particularly when operating at sludge concentrations higher than 15 g L−1. The supersaturated dissolved oxygen (SDOX) system has been proposed as an alternative for supplying dissolved oxygen (DO) at high mixed liquor suspended solids (MLSS) concentrations. The advantages introduced by such technology include the possibility of operating WWTPs at much higher than usual MLSS concentrations, increasing the treatment capacity of WWTPs. Recent studies have demonstrated that the SDOX system has higher oxygen transfer rates (OTRs) and oxygen transfer efficiencies (OTEs) relative to fine-bubble diffusers. However, it is unknown if the high-pressure conditions introduced by SDOX may possibly impact the biological performance of WWTPs. In this study, the effects of SDOX technology on the biological performance of a membrane bioreactor (MBR) were evaluated. The MBR was operated at an MLSS concentration of approximately 15 g L−1 in four phases as follows: (P1) with bubble diffusers, (P2) with an SDOX unit, (P3) with the bubble diffusers, and (P4) with the SDOX unit. The performance of the MBR was assessed by monitoring the sludge concentration, as well as changes in the particle size distribution (PSD), sludge activity, organic matter removal and nitrification performance, and changes in the microbial community within the MBR. The operational conditions exerted by the SDOX technology did not affect the concentration of active biomass during the study period. The biological performance of the MBR was not affected by the introduction of the SDOX technology. Finally, the microbial community was relatively stable although some variations at the family and genus level were evident during each of the study phases. Therefore, the SDOX system can be proposed as an alternative technology for DO supply in WWTPs increasing the overall treatment capacity.

A Novel Method to Determine Blower Capacity of Wastewater Treatment Plants for Dry and Wet Weather Conditions

A Novel Method to Determine Blower Capacity of Wastewater Treatment Plants for Dry and Wet Weather Conditions

An Integrated Methodology Using Extended Swara and Dea for the Performance Analysis of Wastewater Treatment Plants: Turkey Case.

Public and private companies make significant water infrastructure investments to meet increasing water demand. In this context, investments in wastewater treatment plants (WWTPs), which play an important role in recycling of used water, are also increasing. This study investigates determination of the efficiency scores of WWTPs considering each metropolitan municipality as a decision-making unit (DMU). In this study, a two-step methodology is established to determine efficiency scores of WWTPs. In the first step, the input and output parameters are searched by a literature review for the performance evaluation, and candidate parameters are determined. Then, to determine the most appropriate and related parameters, the importance weights of all candidate inputs and outputs are computed using the extended stepwise weight assessment ratio analysis (SWARA) method. Next, the inputs and outputs are chosen according to their importance weights. In the second step, efficiency scores of WWTPs are calculated using output-oriented data envelopment analysis (DEA) models. Based on the expert opinions, the parameters used as input variables are as follows: Daily Wastewater Amount per Person Discharged in Municipalities, WWTP Capacity, and Number of WWTPs; and the parameters used as output variables are as follows; Amount of Wastewater Treated in WWTPs and Municipal Population Served by WWTPs. The results are presented and discussed by sensitivity analysis. Results show that 14 metropolitan municipalities have total efficiency, 19 metropolitan municipalities have technical efficiency, and 21 metropolitan municipalities have scale efficiency.

Evaluasi Pengelolaan Instalasi Pengolahan Air Limbah Puskesmas

Community health centers are releasing infectious wastewater that must be treated using a Wastewater Treatment Plant (WWTP). The performance of WWTP will affect the quality of effluent wastewater, while the quality has been determined by the Governor of East Java Regulation No. 72 of 2013, so as not to pollute the environment. This research purposed to evaluate the management of WWTP incommunity health center in Surabaya, which covers the north, south, east and west. This research analyzed the installation of 5 wastewater treatment plants, consisting of 2 WWTP Non-Inpatient Health Centers with the highest population category, and 3 Inpatient Health Centers with the highest number of beds. Data collection was obtained from observations, interviews and laboratory tests. Wastewater samplings were carried out at the inlet, after filtration and outlet. Data were analyzed descriptively and compared with East Java Governor Regulation No. 72 of 2013 and WWTP Technical Guidelines. The results of the research showed that the effluent quality of the Surabaya City Health Center wastewater treatment plant has met the quality standards. The discharge of wastewater community health centersnot exceed the maximum discharge of wastewater, but the Tanah Kalikedinding and the Jagir Health Center produced wastewater exceeding the discharge capacity of WWTP, so that the performances becomes less efficient. In terms of management, only Dr. Soetomo health center had sufficient grades, while others got excellent grades.

Upgrade of the Taskila WWTP with an MBR line: the first treatment results, performance assessment and lessons learnt

Abstract In this paper, we present the first results of a large-scale membrane bioreactor application implemented for increasing the wastewater treatment plant capacity. The Taskila plant in Finland was upgraded in 2018 and is now operated as a hybrid system with parallel membrane bioreactor and conventional biological lines. The results showed that membrane filtration improved the plant performance significantly in terms of the solids and pathogens removal. Nitrogen removal has been stable with the current operating set-points and notably better than before the plant expansion. The analysis using key performance indicators showed that there were no significant differences in operational expenditures between the membrane and conventional lines. The membrane filtration results highlight the importance of maintaining the good sludge filterability properties that enable higher operational fluxes and reduced energy consumption. The low membrane aeration flow-rate mode, the standard operating mode with good sludge filterability, enabled reduction of total aeration energy consumption by 34% for the membrane bioreactor, including both activated sludge and membrane aeration. Fine-tuning of the hybrid plant is still going on and, therefore, improved overall results are expected in the forthcoming years.

Performance analysis and economic assessment of a combined cooling heating and power (CCHP) system in wastewater treatment plants (WWTPs)

Wastewater treatment plants (WWTPs) have great potential as a renewable energy source because of producing biogas. Due to electrical, heating and cooling demands in WWTPs, combined cooling heating and power (CCHP) systems are an appropriate choice through the energy systems. In this study, a novel integrated WWTP-CCHP system is performed to investigate the system performance from energy and economic perspectives. The effect of various parameters on the performance, payback period and profitably index of the system are studied. To increase the system electrical efficiency, a combination of a micro gas turbine and an organic Rankine cycle (ORC) is utilized. The excess heat is used to provide thermal demand for an anaerobic digester. Due to declining digester thermal demand in the hot season, the residue of heat is employed for absorption chiller. Also, hot water is produced as a byproduct throughout the year. The CCHP system shows a lower energy efficiency and greater payback period and profitably index at high capacity of WWTP. The optimization of the system increases the electrical efficiency with a shorter PB and higher PI in all working conditions.

First quantification of semi-crystalline microplastics in industrial wastewaters

Microplastics enter natural water bodies by a variety of pathways, one of them being wastewater streams. The role of industrial wastewater in overall microplastic emissions has so far only been estimated, because access is usually restricted. This is the first report providing quantitative data on microplastics in industrial wastewaters. The wastewater discharge of three different industrial sites was sampled in the size ranges of small microplastics (10–1000 μm) and large microplastics (1000–5000 μm). Differential scanning calorimetry (DSC) was used to detect and quantify semi-crystalline thermoplastics. Polyethylene (PE) and polypropylene (PP) were the most abundant polymers, but polyamide (PA) and polyethylene terephthalate (PET) were also found. As all three industrial sites had wastewater treatment plants (WWTP), the total concentrations were in the μg L−1 range, comparable to organic micropollutants in municipal WWTP effluents. At one industrial site, the removal capacity of the WWTP was evaluated by sampling and analyzing the influent as well as the effluent. The total microplastics concentration in the influent was in the g L−1 range, yielding a removal capacity of the industrial WWTP of >99.99 %.

Scenarios for treatment of sewage sludge from municipal wastewater treatment plants in Hanoi towards energy efficiency and resource recovery

Wastewater treatment plants (WWTPs) generate significant amount of sewage sludge (SS). Besides, faecal sludge (FS) generated from popularly existing septic tanks in cities need also adequate treatment. Selection of appropriate sludge treatment options is among most challenging wastewater management issues for fast growing cities. The case study has selected the central part of Hanoi city, with expected population of 2,145,437 persons by 2030, total design capacity of WWTPs 588,300 m3/day, whereas different options of SS and FS management were analysed. The calculation results shown that an energy required for operation of sludge treatment processes in scenarios 2, 3 and 4 could be fully self-sufficient. Besides, with total energy demand for operation of WWTPs was of 311,799 kWh/day, 21.3% (scenario 2), 99.3% (scenario 3) or 71.3% (scenario 4) of demand could be covered by remaining biogas produced from anaerobic co-digestion of SS and FS. A conventional SS treatment process, dewatering by centrifuge and dumping dewatered sludge to the landfill (scenario 1) did not generate any energy but required an energy of 17,371 kWh/day for SS treatment and dumping. Anaerobic co-digestion of SS, FS, other organic fractions, can be a promising sludge management solution aiming at energy efficiency and resource recovery.

Repeated Hurricanes Reveal Risks and Opportunities for Social-Ecological Resilience to Flooding and Water Quality Problems.

Hurricanes that damage lives and property can also impact pollutant sources and trigger poor water quality. Yet, these water quality impacts that affect both human and natural communities are difficult to quantify. We developed an operational remote sensing-based hurricane flood extent mapping method, examined potential water quality implications of two "500-year" hurricanes in 2016 and 2018, and identified options to increase social-ecological resilience in North Carolina. Flooding detected with synthetic aperture radar (>91% accuracy) extended beyond state-mapped hazard zones. Furthermore, the legal floodplain underestimated impacts for communities with higher proportions of older adults, disabilities, unemployment, and mobile homes, as well as for headwater streams with restricted elevation gradients. Pollution sources were repeatedly affected, including ∼55% of wastewater treatment plant capacity and swine operations that generate ∼500 M tons/y manure. We identified ∼4.8 million km2 for possible forest and wetland conservation and ∼1.7 million km2 for restoration or altered management opportunities. The results suggest that current hazard mapping is inadequate for resilience planning; increased storm frequency and intensity necessitate modification of design standards, land-use policies, and infrastructure operation. Implementation of interventions can be guided by a greater understanding of social-ecological vulnerabilities within hazard and exposure areas.