Stabilization Ponds Research Articles

All About Wastewater Treatment Technologies and Application Options

Nowadays, an enormous amount of wastewater is generated, whether by industrial or human activities. Wastewater contaminated with toxic compounds can endanger the ecosystem and human health if released into the environment untreated or partially treated. For this reason, polluted industrial wastewater must be effectively treated before it is discharged into the environment. Although conventional wastewater treatment can efficiently reduce nitrogen and carbon concentrations, it is ineffective in removing so-called emerging pollutants (e.g., pharmaceuticals, pesticides, and personal care products). These compounds pass through the wastewater treatment plant unchanged and enter the environment in this way, posing a threat to nature and human life. Many of the emerging pollutants cause endocrine disruption or are carcinogenic. Efficient treatment is therefore urgently needed to remove these compounds before they enter the environment or water bodies. This special issue of the journal CLEAN – Soil, Air, Water includes the latest available technologies to treat industrial wastewater. It covers extensively the advancement in biological treatments, advanced oxidation techniques, and membrane technology to remove water pollutants. Having an easy-to-use guider manual for all the enlisted smart techniques, it also describes and discusses the emerging futuristic technologies in industrial pollutant removal from wastewater. Here, the new and emerging innovative trends in bioremediation of hazardous pollutants present in wastewater are discussed in depth. It also includes the fate of pollutants produced after the treatment process both at the laboratory scale and at the industrial scale. The special issue intrusively explores the unique biological aspects of the wastewater treatment process and highlights the advantages they provide for engineering applications in various industries. Each paper covers a different biological-based approach and examines the basic principles, practical applications, recent breakthroughs, and associated limitations. It presents an array of cutting-edge wastewater treatment research and thereafter its applications in treatment, remediation, sensing, and pollution prevention processes. The biological process for application in wastewater research has a significant impact on maintaining the long-term quality, availability, and usability of water. In this special issue, biological wastewater treatment technologies are explained. The biological processes presented in wastewater treatment processes include: 1) bioremediation of wastewater that includes aerobic treatment (oxidation ponds, aeration lagoons, aerobic bioreactors, activated sludge, percolating or trickling filters, biological filters, rotating biological contactors, and biological removal of nutrients) and anaerobic treatment (anaerobic bioreactors and anaerobic lagoons); 2) phytoremediation of wastewater that covers constructed wetlands, rhizofiltration, rhizodegradation, phytodegradation, phytoaccumulation, phytotransformation, and hyperaccumulators; and 3) mycoremediation of wastewater. The special issue describes a broad area of biological processes and water research which are considered key components for advanced water purification. It also includes the desalination technologies that remove, reduce, or neutralize water contaminants that threaten human health and/or ecosystem productivity and integrity. This special issue is mainly related to each of the main factors contributing to the removal of toxic pollutants from wastewater, namely, methods and procedures, materials (especially low-cost materials originating from industrial and agricultural waste), wastewater management, valorization possibilities of waste resulting from wastewater treatment processes, etc. This special issue is especially devoted to industrial wastewater treatment and aims to present the current state-of-the-art and innovative research that addresses these challenges, so that wastewater treatment systems can adapt and be fit for purpose, robust, and resilient for the next 100 years. It is equally beneficial for students and professors for understanding the new research advancements in this field. The main objective of this special issue is to summarize the work of the eminent scientists in this field to provide a clear but concise chapter that can be used as a quick reference for environmental engineers and researchers, and to be effectively implemented in higher education teaching undergraduate and graduate students, as well as extension and outreach.

Eichhornia crassipes-rhizospheric biofilms contribute to nutrients removal and methane oxidization in wastewater stabilization ponds receiving simulative sewage treatment plants effluents

Wastewater stabilization ponds (WSPs) have been used in treating sewage treatment plants (STPs) effluents. However, little is known about the role of rhizospheric biofilms on methane release in WSPs with floating plants. In the present study, the nutrient removal, CH4 fluxes, CH4 oxidization potential and rhizospheric bacterial community were investigated in WSPs with Eichhornia crassipes under simulate STPs effluents for 31 days. At the end of the experiment, E. crassipes biomass was 5.60–8.81 times of initial weight and increased with increasing nutrients concentration. E. crassipes effectively reduced methane release and nutrients. Compared to control, E. crassipes reduced 52.30%–83.21% of CH4 fluxes at water-atmosphere interface and had better inhibition effect on CH4 fluxes in treatments with high nutrients. However, methane oxidization rates of E. crassipes roots were higher in low nutrients (0.83 ± 0.046 mg CH4 (kg fresh plant)−1 day−1) than high nutrients (0.12 ± 0.04 mg CH4 (kg fresh plant)−1 day−1). Structural equation modeling revealed that biomass of E. crassipes has negative effect on CH4 fluxes (−0.453, p = 0.000). Proteobacteria, Bacteroidetes, Planctomycetes, Chloroflexi and Actinobacteria were the predominant phyla in the rhizospheric biofilm of E. crassipes and contributed to nutrients removal. Aerobic methanotrophs and pomA abundances were higher in rhizospheric biofilm exposed to high nutrients than low nutrients and aerobic methanotrophs had close interactions with other microorganisms and participated in the carbon and nitrogen cycle, demonstrating that many bacteria harboring pmoA gene did not fully involve in methane oxidization. These data highlight plants E. crassipes have an important role in both reducing methane release and nutrients removal.

Methane Emissions from Municipal Wastewater Collection and Treatment Systems.

Municipal wastewater collection and treatment systems are critical infrastructures, and they are also identified as major sources of anthropogenic CH4 emissions that contribute to climate change. The actual CH4 emissions at the plant- or regional level vary greatly due to site-specific conditions as well as high seasonal and diurnal variations. Here, we conducted the first quantitative analysis of CH4 emissions from different types of sewers and water resource recovery facilities (WRRFs). We examined variations in CH4 emissions associated with methods applied in different monitoring campaigns, and identified main CH4 sources and sinks to facilitate carbon emission reduction efforts in the wastewater sector. We found plant-wide CH4 emissions vary by orders of magnitude, from 0.01 to 110 g CH4/m3 with high emissions associated with plants equipped with anaerobic digestion or stabilization ponds. Rising mains show higher dissolved CH4 concentrations than gravity sewers when transporting similar raw sewage under similar environmental conditions, but the latter dominates most collection systems around the world. Using the updated data sets, we estimated annual CH4 emission from the U.S. centralized, municipal wastewater treatment to be approximately 10.9 ± 7.0 MMT CO2-eq/year, which is about twice as the IPCC (2019) Tier 2 estimates (4.3-6.1 MMT CO2-eq/year). Given CH4 emission control will play a crucial role in achieving net zero carbon goals by the midcentury, more studies are needed to profile and mitigate CH4 emissions from the wastewater sector.

Types and Treatment Technology of Industrial Wastewater

In the recent past, water contamination is an alarming topic for humans, the environment and other living beings. Water becomes wastewater after its use for different purposes in daily life or industries. As the population is growing rapidly, the amount of wastewater is increasing day by day for its high demand which has a large adverse effect on our environment and daily life. Industries are the major consumers of fresh water and so they produce a large amount of industrial effluents. Due to the large effluents containing toxic pollutants (e.g., dyes, heavy metals, surfactants, personal care products, pesticides, pharmaceuticals) from agricultural, municipal, and industrial resources, water becomes contaminated and its properties like the smell, color, COD, BOD, Turbidity, pH, TDS, etc. have been changed drastically. This change in water quality has a great effect on human health and the aquatic environment. To maintain the ecological environmental balance and to ensure fresh water for living beings, water has to be treated effectively. There are several techniques for the treatment of industrial wastewater such as adsorption, coagulation/Flocculation, chemical precipitation, advanced oxidation process, anaerobic system, stabilization pond, etc. The selection of treatment procedure varies from one type of industry to another as wastewater contains different pollutants. This paper focuses on the characteristics of industrial wastewater, its treatment steps, different treatment methods and sludge treatment used in industries for the treatment of effluents.

Pollution status and risk assessment of heavy metals in the sediment of a historically contaminated lake treated by oxidation pond in China.

Sediment plays animportant role in controlling biogeochemical cycling of heavy metals in aquatic environment. The Ya-Er Lake is a typical lake which was historically contaminated by heavy metals in Hubei province, China. After industries surrounding the Ya-Er Lake being shut down, oxidation pond treatment and dredging program were conducted for pollution management since 1970s. To date, the Ya-Er Lake has been used for aquaculture for several decades. However, the status of heavy metal levels and ecological risks in this lake remains unclear. Herein, concentrations, chemical fractions, and risk assessment of heavy metals were investigated in the Ya-Er Lake sediment. Results showed that concentrations of heavy metals in the Ya-Er Lake sediment were higher than other reported lake systems, suggesting that heavy metal pollution in the Ya-Er Lake is still serious. Relatively higher proportions of carbonates bound form of Cd and Ni indicated high-risk potential of these two heavy metals, and Cd and Ni should be listed as the primary heavy metal pollutants in the Ya-Er Lake according to the results of potential ecological risk index (PERI) and sediment quality guidelines (SQGs). The risk assessment code (RAC) analysis showed that Ni and Cd poses higher bioavailability and mitigation potential, and may affect the Ya-Er Lake ecosystem and downstream aquatic environment. These findings reflected that oxidation pond treatment and dredging sediment to near place are not effective to control heavy metal pollution, and a long-term ecological risk is still posed to surrounding aquatic environment. Our study provides scientific basis on pollution control and management in aquatic system contaminated by heavy metals.

Pond-in-Pond's anaerobic pit performance over conventional anaerobic ponds – A computational fluid dynamics comparison

Waste stabilization ponds (WSP) are recommended to treat wastewater in small communities. However, due to lack of pond hydraulics knowledge and uncertainties in conventional pond designs, a novel design, the Pond-in-Pond (PIP), was proposed. This design combines an anaerobic pit surrounded by berms into an integrated aerobic pond. Although this design promotes a more reliable operation, the unknown factor is the most appropriate configuration. Thus, to improve the anaerobic pit's design, a series of computational fluid dynamics (CFD) simulations were evaluated. In total, 13 configurations were compared, consisting of three different length-to-width ratios (LWR), 1:3, 1:1, and 3:1. Each LWR was simulated with the outflow exiting the pit through 1, 2, 3, or 4 sides; and, a conventional anaerobic pond with a 3:1 LWR was simulated for reference. The assessment was based on 1) the hydrodynamic velocity profile; 2) a computational tracer test using an Eulerian model to identify the short circuit index, hydraulic retention time and hydraulic efficiency; and 3) the solids' retention capacity in the critical path using Helminths eggs as a reference. The CFD simulations showed the 1:1 LWR (square pit) performed better overall when compared to the 1:3 and 3:1 LWR, and much better than the anaerobic pond. The square pit presented lower velocities, larger hydraulic efficiency, and higher solids' retention capacity, settling particles as small as 50 μm, such as Hookworms. Despite the velocity profiles presented statistically significant differences in the number of sides outflowing, the tracer test demonstrated that the differences were negligible.

Seasonal Species Diversity and Dominance of Phytoplankton in Different types of tropical Domestic Sewage Oxidation Ponds

Planktons are small microscopic organisms, comprising diatoms and algae, which form the basis of primary production and the zooplankton, which are mainly crustaceans, rotifers and larval stages of larger animals. Both are the bio-indicators of a water body, constituting the main food for the carnivorous and omnivorous fishes in any aquatic ecosystem. In the present study, the species diversity, and their abundance with a total and average population of various species of phytoplankton have been studied in the primary and secondary domestic oxidation ponds along with a freshwater control pond situated at Shahpura. Bhopal, Madhya Pradesh, India. Physicochemical parameters like light penetration, water temperature, pH and DO were also analyzed along with the phytoplankton population in both types of ponds to assess their impacts. The samples were collected and identified using standard methods. The results revealed that the phytoplankton groups like Chlorophyceae, Bacillariophyceae, Cyanophyceae and Euglenophyceae were dominantly found in the sewage oxidation ponds along with about 20 species of phytoplankton in varying population densities in different seasons. A similar analysis was done in a freshwater control normal pond for comparison. Physicochemical parameters in these secondary sewage oxidation ponds with a high nutrient load were found to be highly favourable for the growth of the plankton species. A comparatively low number of phytoplankton was recorded in the freshwater control pond, which was highly deficient in nutrients.

Mathematical modeling and optimization of wastewater stabilization ponds using nonlinear programming

This research work proposes a mathematical optimization model for constructing two ponds (1. Facultative pond and 2. Maturation pond) provided in series. The model uses concrete volume as its objective minimization function. There were two decision variables; the first was the detention time (DT) and the second in the list was the number of provided baffle walls (NBW) in both ponds. The constraint parameters include fecal coliforms and biochemical oxygen demand (BOD5). The model was applied with the help of an Add-Ins of MS Office: Excel solver. The generalized reduced gradient algorithm was utilized in the solver (GRG). Before applying the mathematical optimization model, ponds were designed with the conventional method and then using optimized values of the variables. A comparison of the findings reveals that a 13.79 percent reduction in the DT, an 11.55 percent reduction in the area, and a 7.19 percent reduction in the volume of concrete occurred. The reduction values mentioned above are significant since these systems' fundamental drawback is the area's requirement. In addition, sensitivity analyses of the objective function and the removal of pollutants are also provided. The model described above is sensitive to variations in the parameters. Both analyses demonstrated that the effluent characteristics comply with the class-B irrigation standards in Turkey. It is advised to do more optimization studies for WSPs with the help of other algorithms and tools available in the literature for distinct wastewater treatment plants.

Wastewater treatment effectiveness is facilitated by crucial bacterial communities in the wetland ecosystem.

Microorganisms play essential roles in nutrient removal and biogeochemical cycling during wastewater treatment. However, little is known about the main roles of key functional bacterial communities in wastewater treatment processes. We collected 18 water samples and 15 sediment samples from the six operational subsystems of the constructed wetland, among which the contact oxidation pond, enhanced hybrid biofilm reactor, and central stabilization pond are the main wastewater treatment units in the constructed wetland, and then investigated the bacterial communities using 16S rRNA gene targeting and sequencing to address this knowledge gap. The results indicated that the composition of the bacterial community is closely related to the efficiency of pollutant removal. The abundant carbon metabolism function increased the removal of nitrate‑nitrogen (NO3--N) and total nitrogen (TN) by the contact oxidation pond by 89.84 % and 38.91 %, respectively. The overlap of ecological niches and the presence of pathogenic bacteria substantially affect effluent wastewater treatment. Second, NO3--N (p < 0.001) was the most important factor driving the bacterial community composition in water and sediments. Furthermore, the positive structure was prevalent in the cooccurrence network of water samples (87.24 %) and sediments (76.53 %) of the wetland, and this positive structure with keystone species was critical for the adaptation of the bacterial community to environmental filtration. In summary, this study reveals the distribution patterns of bacterial communities in different wastewater treatment processes and their driving factors and provides new perspectives on the link between the bacterial community composition and wastewater treatment.

Evaluation of the Richness, Species Diversity, and Biosafety of Saprotrophic Fungal Communities in Constructed Wetlands and Biological Wastewater Ponds

The present study was focused on the characterization of the biocenotic diversity of saprotrophic fungi, taking into account the impact of various treatment systems and technological stages as well as the physicochemical properties of wastewater. The biodegradation potential, the hazard posed to humans, animals, and the environment, and the effectiveness of elimination of propagules were evaluated. The most effective elimination of fungal propagules was recorded in hybrid constructed wetland systems with horizontal (HF-CW) and vertical (VF-CW) wastewater flow, especially in the VF-HF objects. The fungal communities present in wastewater from small constructed wetland (CW) and wastewater stabilization ponds (WSP) were dominated by ubiquitous terrestrial molds accompanied by a minimal number of yeasts. The similarity of the species composition of the fungal communities between the treatment plants was generally low, whereas the species diversity together with the population size was very high at the various stages of wastewater treatment. Species with potential pathogenicity to humans and animals accounted for over 45%, i.e., were classified as BioSafety Level 1 and 2 (BSL-1 and BSL-2 groups), and potentially phytopathogenic fungi represented 31.5% of the mycobiota species composition. The dynamics of fungal growth were correlated with the content of organic pollutants and nutrients (nitrogen and phosphorus) and with oxygen deficiency. The accumulation of nitrates corresponded to the decline in the frequency of fungi in treated wastewater. The lowest efficiency of the removal of fungi was exhibited by the biological wastewater stabilization ponds.

Migration mechanism and risk assessment of per- and polyfluoroalkyl substances in the Ya'Er Lake oxidation pond area, China

The migration mechanisms, sources, and environmental risks of 29 legacy and emerging perfluorinated and polyfluoroalkyl species present in an oxidation pond (Ya'Er Lake) were investigated for treating sewage based on the analysis of their occurrence and distribution. The concentration of per- and polyfluoroalkyl substances (PFAS) in pond area was between 0.30 and 63.2 ng/g dw (dry weight), with the overall average concentration of 8.00 ng/g dw. Notably, the PFAS concentrations in the surface sediments near the sewage outlet in Pond-1 (50.2 ng/g dw) and Pond-5 (average 15.1 ng/g dw) were 1–2 orders of magnitude higher than those in other areas. In general, the legacy PFAS, i.e., perfluorooctane sulfonic acid was considered to be the major pollutant in the polluted area, on average, accounting for 73.0% of the total concentration of PFAS pollutants. By evaluating the regional distribution of different PFAS homologs, the short-chain PFAS pollutants with lower Kow were found to migrate farther in both horizontal and vertical directions. The sewage outlets in Pond-1 and Pond-5 are the main pollution sources in polluted area and the emerging PFAS pollutants in Pond-5 have replaced the legacy PFAS pollutants as the main pollutants. Based on positive matrix factorization analysis, three main industrial sources of PFAS pollutants in the study area were identified: protective coating, fire-fighting, and food packaging sources. Moreover, the environmental risk assessment results showed that most study areas exhibited medium environmental risk (0.01 ≤ Risk quotient (RQ) < 1), indicating that the ecological environment risks in this area need further attention.

Removal of emerging contaminants in conventional and advanced biological wastewater treatment plants in India-a comparison of treatment technologies

Emerging contaminants (ECs) are a growing concern for the environment and human health. The study investigates 20 commonly reported ECs in 10 wastewater treatment plants (WWTPs) in urban to semi-urban settlements of north India over two years in the summer and winter. The selected plants were based on waste stabilization pond (WSP), up-flow anaerobic sludge blanket (UASB), activated sludge process (ASP), anoxic-aerobic process (AO), anaerobic-anoxic-oxic process, biodenipho process, sequencing batch reactor, and densadeg-biofor process. Of the 20 ECs, all 20 were identified in the influent and effluent, and 13 were identified in the final sludge on at least one occasion. The concentration in the influent, effluent, and sludge varied in the range from 2.5 ng/L to 77.4 μg/L, below limit of detection (LOD) to 1.984 μg/L, and < LOD to 1.41 μg/g, respectively. Acetaminophen and caffeine were predominately detected in the influent, whereas naproxen, ciprofloxacin, and carbamazepine were predominant in the effluent. The total removal in the plants was found in the range of 40.3–68.6%, mainly attributed to biodegradation/biotransformation. Removal of ECs by WWTPs, ranked by a relative removal criterion, followed the order: Biological nutrient removal based plants > WSP > UASB > densadeg-biofor > AO > ASP > combitreat-SBR. The risk assessment showed the risk to algae from antibiotics and triclosan, daphnia from triclosan, and fish from triclosan and hormones.

Polychlorinated dibenzo-p-dioxins/dibenzofurans and mercury in vegetable of the contaminated Ya-Er Lake area: Concentrations, sources, and health risk

The Ya-Er Lake is a seriously polychlorinated dibenzo-p-dioxins/dibenzo-furans (PCDD/Fs) and mercury (Hg)-contaminated lake by pesticide and chlor-alkali plants in China. The oxidation pond method has been conducted to control pollution, moreover, the contaminated sediment was dredged and stacked, becoming a sediment stack yard for vegetable cultivation. To assess effects of oxidation pond method and dredging programme on pollution management and long-term risks of PCDD/Fs and Hg, the concentrations of PCDD/Fs, total Hg (THg), and methylmercury (MeHg) in soil and vegetable sampled from the sediment stack yard were measured and analyzed. Significantly positive relationships between concentrations of PCDD/Fs (p < 0.01), THg, and MeHg (p < 0.05) in edible parts of vegetable and soil were found, suggesting that bioaccumulation from contaminated soil derived from sediment dredging is important sources of PCDD/Fs and Hg in vegetable. Much higher PCDD/Fs (12 ± 9 pg/g dw) and Hg (THg, 0.14 ± 0.23 μg/g dw; MeHg,12.63 ± 13.31 ng/g dw) levels in vegetable were found compared with those from other contaminated regions, indicative of serious PCDD/Fs and Hg pollution in vegetable harvested from contaminated soil. Finally, the calculated provisional tolerable daily intake (PTDI) values showed higher health risk of PCDD/Fs and Hg exposure to local residents through consumption of purple and white flowering stalk, and oilseed rape. Our study established a good model to evaluate the long-term risks of PCDD/Fs and Hg. Moreover, the results indicate that the oxidation pond method and dredging programme were not effective to remove PCDD/Fs and Hg in sediment, which shed new light on management strategy of PCDD/Fs and Hg pollution in contaminated regions.

Characterization of residual solids from mine water passive treatment oxidation ponds at the tar creek superfund site, Oklahoma, USA: Potential for reuse or disposal

Ecologically engineered passive treatment systems have been successfully implemented world-wide to decrease concentrations of ecotoxic metals in mine drainage without continuous energy or material inputs. Typical design life of such treatment systems is approximately 20 years, at which point rehabilitative maintenance must occur. For example, oxidation ponds, designed to accumulate iron (oxyhydr)oxide solids, must be dredged to sustain effective hydraulic retention time, creating large volumes of potentially hazardous waste. In this study, total recoverable and leachable metals in iron (oxyhydr)oxide solids from the oxidation ponds of two multi-cell passive treatment systems in the historic and now derelict Tri-State Lead-Zinc Mining District in Ottawa County, Oklahoma, United States were characterized using several batch leaching tests. This assessment informs potential disposal and reuse scenarios for the solids once they have been removed from the systems. Solids leached nonhazardous concentrations of metals under Resource Conservation and Recovery Act guidelines. However, some metals exceeded Oklahoma Water Resources Board criteria for protection of public water supplies, and total metals exceeded some consensus-based toxicity benchmarks for soils and sediments. Beneficial reuse plans for the iron (oxyhydr)oxides must consider these potential risks. • Batch leaching tests were used to determine trace metal leachability • Iron oxides from hard rock mine drainage were found to be nonhazardous under RCRA • Leachates from SPLP and FLT exceeded some state water quality standards • Iron oxides contained trace metals exceeding sediment and soil quality guidelines

Potentialities of plant based hybrid wetland systems for the treatment of household waste water using Canna indica, Agave americana, Pistia stratiotes and Tagetes erecta

The ever increasing population is generating large amount of waste water and it is increasing with time especially with the higher per capita consumption of water in the country. Besides, the ample amount of energy required by the conventional water treatment methods is hampering the economic viability of the procedure. This asks for newer and efficient low cost nature based water treatment system which along with cost takes into consideration the sustainability of the ecosystem. In this study a hybrid plant based wetland system consisting of four plant species were used to treat the household grey water. Agave americana and Tagetes erecta were used in constructed wetland, Canna indica plant was used in floating raft wetland and Pistia stratiotes in oxidation pond for a period of 24 h retention to know the efficiency. The pollution reduction was analysed after 2 h, 4 h, 6 h, 8 h and 24 h hydraulic retention period (HRT) in all these systems. Three parameters basically BOD, COD and salinity reduction were checked as an initial research to know the viability. The results showed that BOD reduction ranged from 6.67 to 41.18% in various systems within 24 h of retention, whereas COD showed a reduction range of 5.32–35.47% and salinity exhibited a reduction range of 6.93–21.49% based on the different systems.

Multi-Criteria Analysis for Evaluating Constructed Wetland as a Sustainable Sanitation Technology, Jordan Case Study

There is a growing demand for integrating an assessment tool to select wastewater treatment alternatives based on sustainability in the Jordanian wastewater sector. The sector in Jordan has a unique and critical situation that has raised concerns among stakeholders, including donors, and international and national organizations, to carefully select a sustainable treatment system for each case. The Jordanian government set a tool to distinguish between treatment systems, and this tool is mainly focused on financial criteria. However, the sector needs to integrate assessment tools with a wider consideration of other sustainability criteria. Usually, stakeholders are not equipped with a clear methodology to perform sustainability assessments. Therefore, this study proposes and develops a Multi-Criteria Analysis (MCA) tool to evaluate wastewater treatment alternatives from a sustainability perspective for a case study in Jordan—Al Azraq town. Firstly, the study explored the decision and organizational context of the wastewater sector through several interviews. Secondly, assessment criteria and indicators were proposed to compare three proposed treatment alternatives. Finally, the Analytical Hierarchy Process (AHP) was applied with composite scores to evaluate wastewater treatment alternatives. Finally, The results of the composite scores indicated that French Constructed Wetland (FCW) was the best option for this case study, with a score of 3.13, followed by Stabilization Pond (SP) as the second sustainable option, with a score of 2.67, and lastly, Activated Sludge (AS), with a score of 2.07. Several conclusions have been highlighted during the process development, such as the importance of selecting sustainability indicators carefully, and engaging stakeholders during the design and implementation of the assessment.

Insights into the Domestic Wastewater Treatment (DWWT) Regimes: A Review

It is expected that, by 2050, the rapid rise in population and simultaneous urbanization shall deplete clean water supplies. Domestic wastewater (DWW) contains inorganic and organic components that can be harmful to aquatic organisms. Traditional remediation approaches (physical, chemical and biological) can be used on-site or off-site to purify polluted domestic water (activated sludge, built-wetlands, stabilization ponds, trickling filters and membrane bioreactors), and each has its own advantages and limitations. Biosorption through microorganisms, bacteria (microbe-mediated remediation), fungi (mycoremediation) and algae (phycoremediation) has shown promising results in removing toxic chemicals and nutrients. The type of waste and its concentration, heterogeneity level and percentage of clean-up required; and the feasibility of the clean-up technique and its efficiency, practicability, operational difficulties, environmental impact and treatment costs are all factors that are to be considered when choosing a technique for domestic wastewater treatment (DWWT). This review focuses on the roles of conventional methods in DWWT, including their merits, demerits and future prospects. It promotes the concept of “reduce, reuse and recycle” of DWWT and also highlights the problem of emerging contaminants in WWT regimes. We provide insights into the different membrane filtration procedures and water purification techniques and the synergism of conventional and non-conventional WWT strategies for human and environment health security.

The reliability and process capability assessment of suspended growth sewage treatment plant in Melaka, Malaysia.

This paper presents the promising method of synchronizing the Six Sigma and reliability analyses at 15 sewage treatment plants (STPs) operating in Melaka, Malaysia. Five different suspended growth treatment technologies in various capacities were investigated. The sequential batch reactor (SBR) and extended aeration activated sludge (EAAS) processes, conventional activated sludge (CAS), aerated lagoon (AL), and oxidation pond (OP) were compared using innovative Niku's treatment reliability and Six Sigma process capability method for biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), oil and grease (O&G), and ammoniacal nitrogen (NH3-N) effluent parameters and justified the importance of understanding the lognormal behavior of the effluent parameters in interpreting the performance monitoring results and discharge compliance. The results showed that the SBR and EAAS systems relatively fulfilled the highest performance (>95%) compared to conventional systems to ensure the high quality of effluent discharge. Although the whole system is incapable of removing nutrients efficiently, ranging between 42.31% and 90.48%, may lead to eutrophication issues. Process modification and treatment control should become a critical priority in order to reduce variability, improve stability, and increase the efficiency of nutrient removal. These initiatives promote global sustainable development goals (SDGs) 2030 and the domestic water sector transformation (WST) 2040 by treatment cost reduction, improving environmental sustainability and guaranteeing social and health benefits.

Contaminants of emerging concerns (CECs) in a municipal wastewater treatment plant in Indonesia

This study provides the first set of quantitative data on the occurrence and fate of a wide range of contaminants of emerging concerns (CECs) in Indonesia’s largest wastewater treatment plant (WWTP). The WWTP employs waste stabilization ponds (WSPs) as the secondary treatment before discharging the effluent to the Citarum River. Fourteen out of twenty-two monitored CECs were detected in the wastewater influent, and seven were present in the effluent, with a total concentration of 29.8 ± 0.4 µg/L and 0.5 ± 0.0 µg/L, respectively. The occurrence of the CECs in this study was found to be well correlated with their possible use and known detection in surface waters in Indonesia. Caffeine (CAF) at 12.2 ± 0.1 µg/L, acetaminophen (ACT) at 9.1 ± 0.1 µg/L, N,N-diethyl-m-toluamide (DEET) at 5.0 ± 0.1 µg/L, ibuprofen (IBU) at 2.3 ± 0.0 µg/L, and triclosan (TCS) at 470 ± 64 ng/L were discovered as the five most prevalent CECs, followed by bisphenol A (BPA), trimethoprim (TMP), Tris(2-chloroethyl) phosphate (TCEP), sulfamethazine (SMZ), carbamazepine (CBZ), fluoxetine (FLX), benzotriazole (BTA), sulfamethoxazole (SMX), and metformin (METF). Biodegradable CECs (SMX, SMZ, ACT, IBU, TCS, BPA, CAF, DEET, and TMP) were efficiently removed (83–100%) by the WSP. In contrast, recalcitrant CECs achieved poor removal efficiencies (e.g., FLX at 24%), and for others, treatment processes even resulted in elevated concentrations in the effluent (CBZ by 85%, TCEP by 149%, and BTA by 92%). The CECs’ influent concentrations were determined to pose a moderate aquatic cumulative risk, while no such risk was associated with their effluent concentrations. The study demonstrates the importance of conventional WWTPs in reducing the concentrations of CECs to minimize their aquatic contamination risk. The findings are relevant for countries, such as Indonesia, with limited resources for advanced centralized wastewater treatments, and which are exploring the efficacy of centralized WSP against the existing decentralized treatments.

Effect of Attached Growth on Treatment Performance in Waste Stabilization Ponds

Waste stabilization ponds (WSPs) rely upon natural biochemical reactions for treatment and are used widely across the world. However, WSPs often fail to meet treatment performance expectations due to insufficient hydraulic performance. Installation of baffles can improve hydraulic performance of WSPs by increasing the mean residence time, reducing dead zones, and short circuiting, thus improving pond treatment performance. Theoretically, baffles with the ability to sustain attached growth will increase the possible attachment area of microorganisms and further contribute to nutrient removal. However, to date there have been no full-scale studies exploring attached growth baffles in WSPs. The main objective of this study was to investigate and quantify the effect of attached growth baffles on WSP treatment performance, specifically in terms of improvements in treatment performance provided by attached biofilm compared with hydraulic improvement. A first-order kinetic model was used to predict biological oxygen demand (BOD) removal efficiency, including suspended and biofilm biomass reactions, to determine whether attached growth or hydraulics had the most influence on performance improvement. At the operational WSP scale, we found that although the presence of attached growth on baffles results in a modest (~0.6%) improvement in treatment performance, the most influential factor for improving treatment was improved hydraulics (~5.3%). In model generalization, the change in biofilm thickness and biofilm area had less effect on treatment in WSPs in higher organic loading scenarios; however, a considerable improvement (~12%) in treatment efficiency could be achieved by doubling the total biofilm area. Overall, this study shows that baffles can not only improve WSP hydraulics but can also be used as a medium for increasing biofilm area to improve WSP biological treatment efficiency.