Existing Sewage Treatment Plants Research Articles

OVERVIEW OF ROOT ZONE TECHNOLOGY

Central Pollution Control Board (2007) study found that discharge of untreated sewage is sthe single most important cause for surface and ground water pollution n India. There is a large gap between the generation and treatment of domestic wastewater in India. The problem is not only that India lacks sufficient treatment capacity but also that the existing sewage treatment plants are not operated and are not maintained. Most of the government-owned sewage treatment plants remain closed due to improper design, poor maintenance, or lack of reliable electricity supply to operate the plants, absentee employees, and poor management. The wastewater generated in these areas normally percolates in the soil or evaporates. The uncollected wastes accumulate in the urban areas cause unhygienic conditions and release pollutants that leach to surface and groundwater. Moreover, where these treatment plants exist, the cost of treatment is so high that industrialists favour not treating the waste generated and directly dumping the untreated waste into the rivers.The Root Zone Treatment system (RZTS) also known as the reed bed system or constructed wetland system is a sealed filter bed consisting of a sand/gravel/ soil system, occasionally with a cohesive element, planted with vegetation that can grow in wetlands. After removing coarse and floating material, the wastewater passes through the filter bed where biodegradation of the wastewater occurs. The functional mechanisms in the soil matrix responsible for the mineralization of biodegradable matter are characterized by complex physical, chemical and biological processes resulting from the combined effects of the filter bed material, wetland plants, micro-organisms and wastewater. The root zone treatment system also known as the reed bed or constructed wetland system is a sealed filter bed consisting of a sand /gravel/soil system.

Anaerobic co-digestion of food waste and bio flocculated sewage sludge towards bio-methane production

The existing sewage treatment plants are energy consumers rather than producers and integration of anaerobic reactor can be a viable approach for enhancing their commercial viability. Therefore, anaerobic co-digestion of food waste and bio-flocculated sewage sludge was studied in a continuous stirred tank reactors (R1 and R2) having a working volume of 6.5 Litre at organic loading rates of 2.5 and 2.4 g VS L−1D−1. At mesophilic temperature, the stabilisation of inoculum was performed in batch mode for 60 days followed by continuous mode feeding for 120 days. The feeding ratio was decided based on availability of food waste and bio-flocculated sewage sludge from a typical domestic household for analysing the effect of volatile fatty acids accumulation on reactor performance. The R1 was fed with equal proportion of bio-flocculated sewage sludge and food waste while R2 was fed in 98:2 (v/v), respectively. To analyse the mixing and temperature distribution within the digester, the velocity and temperature profiles were obtained using Ansys Fluent. In R1, more biogas yield were observed than R2 due to 80% average VS reduction as compared to 55% in case of R2. The highest volatile fatty acids accumulation of 10951 mg L−1 was observed in R1 whereas R2 showed 2800 mg L−1, respectively. The more fluctuations in pH were observed in R1 as compared to R2 due to more food waste concentration and maximum bio-methane production was 133 and 233 mL CH4 g−1 VSadded in R1 and R2, respectively.

Assessing sustainability of microalgae-based wastewater treatment: Environmental considerations and impacts on human health

An integrated life cycle assessment (LCA) and quantitative microbial risk assessment (QMRA) were conducted to assess microalgae-mediated wastewater disinfection (M-WWD). M-WWD was achieved by replacing ultraviolet disinfection with a microalgal open raceway pond in an existing sewage treatment plant (STP) in India. Regarding impacts on human health, both M-WWD and STP yielded comparable life cycle impacts, around 0.01 disability-adjusted life years (DALYs) per person per year. However, QMRA impacts for M-WWD (0.053 DALYs per person per year) were slightly lower than that for STP while considering exposure to E. coli O157:H7 and adenovirus. Additionally, a comparative LCA resolved the dilemma about the appropriate utilization of microalgal biomass. Among biodiesel, biocrude, and biogas production, the lowest impacts of 0.015 DALYs per person per year were obtained for biocrude for 1 m3 water treated by M-WWD. Electricity consumption in microalgae cultivation was a major environmental hotspot. Overall, M-WWD, followed by production of microalgal biocrude, emerged as a sustainable alternative from environmental and public health perspectives. These findings set the foundation for pilot-scale M-WWD system development, testing, and economic evaluation. Such comprehensive investigations, encompassing LCA, QMRA, and resource recovery scenarios, offer crucial insights for stakeholders and decision-makers in wastewater treatment and environmental management.

Tertiary treatment using ultrafiltration in an existing sewage treatment plant for industrial reuse: a modelling approach using artificial neural network with uncertainty estimation

Abstract Navi Mumbai Municipal Corporation of Maharashtra state, India, unified a tertiary treatment plant (TTP) of 20 × 103 m3/day capacity with ultrafiltration technology in an existing Koparkhairane sewage treatment plant (STP) for producing effluent quality usable for industrial purposes. As prior art, an artificial neural network-genetic algorithm (ANN-GA) along with uncertainty estimation using prediction interval is employed to model secondary treated effluent (STE) flow rate (QT) and other quality parameters such as biochemical oxygen demand, chemical oxygen demand, and total suspended solids (TSS) to conclude the reliability of the range in which the input available to TTP. ANN-GA model provides a coefficient of determination above 0.90 for all STE parameters modelled other than TSS. Inferring that a good quantity and quality of 20 × 103 m3/day STP treated water is currently available, where a decreasing trend of QT is also noticed and highlighted. Further, the Wilcoxon signed-rank test on the quality parameter of effluent TTP for industrial reuse standard infers TSS shows infringement during the initial period but started adhering to standards over time. The research delineates at the outset of exploring water reuse policy in India, emphasizing Maharashtra state, modelling STE using ANN-GA and performance evaluation of TTP.

Challenging treatment of food wastes for cleaner production after the African swine fever outbreak in South Korea

Food waste is a growing global concern, necessitating effective treatment solutions. South Korea stands out with over 90% of its food waste being recycled, driven by robust resource circulation policies. Across Asia, anaerobic digestion processes are favored for food waste treatment due to their economic and environmental advantages. The South Korean Government aims to expand anaerobic digestion to ensure stable organic waste treatment. However, the 2019 outbreak of African swine fever (ASF) in pig farms led to the cessation of wet feed production, comprising 22% of total feed. This has increased the pressure on alternative recycling methods. The handling of food waste leachate, generating around 1080 t/d during treatment, has become a concern due to the discontinuation of wet feed production. The objective of this study is to develop a food waste policy. It begins by assessing food waste and leachate generation through field surveys of 346 treatment facilities engaged in pretreatment, feeding, composting, and biogasification. To mitigate the impact of ASF outbreaks in the short term, a proposed solution involves diverting food waste leachate to existing sewage treatment plant digesters during non-injection weekends and other off-peak times. This measure aims to completely treat the maximum discharge of approximately 2000 t/d during the peak summer ASF outbreak periods. For the long term, a strategy involving anaerobic digestion is suggested in response to the gradual reduction in wet or dry feed production, along with composting, the conventional treatment method. This transition not only curbs greenhouse gas emissions but also enhances biogas production, a renewable energy source. These efforts align with the Korean Green New Deal’s goal of achieving a 20% share of renewable energy by 2030.

Performance appraisal of microbial inoculants treating polluted surface water through bench‐scale investigation

AbstractBACKGROUNDThis study investigates the performance of microbial inoculants by exploring pollutant removal efficiency, microbial viability and substrate removal kinetics for treating polluted surface water. The morphological, elemental composition and biochemical characterization of inoculants were analyzed using field emission scanning electron microscopy with energy dispersive X‐ray spectroscopy (FESEM‐EDX) and Fourier transform infrared (FTIR) techniques. The identification of bacterial strains in polluted feed water also was performed using 16S rRNA partial sequencing. Bench‐scale efficacy of selected microbial inoculants (MI) along with control for each study was performed at variable retention times ranging from 6 to 72 h, under optimum operating conditions.RESULTSThe maximum removal (86% and 90%) of the organic load (chemical and biological oxygen demand, COD and BOD) was achieved by inoculants containing Bacillus subtilis along with other microbial species after 72 h of treatment. The microbial inoculant MI‐2 containing Paracoccus pantotrophus and Pseudomonas Putida exhibited the highest TN removal (66%) after 72 h of contact time. Adenosine triphosphate (ATP) analysis revealed that the active biomass ratio is a more precise indicator of healthy biomass instead of the conventionally used parameter MLVSS (mix liquor volatile suspended solids) in a biological treatment system, which apparently provides a significant addition to the existing knowledge base for the operational wastewater treatment plants (WTPs).CONCLUSIONIn this study, microbial inoculants were found to be frugal and viable treatment tools for the remediation of polluted surface water. Exploiting such inoculants also can overcome the inefficiencies of existing sewage treatment plants by serving as potential tools for bio‐augmenting the indigenous microbial fingerprint of aeration tank/secondary treatment systems. © 2023 Society of Chemical Industry (SCI).

Integrating life cycle assessment with quantitative microbial risk assessment for a holistic evaluation of sewage treatment plant

An integrated approach was employed in the present study to combine life cycle assessment (LCA) with quantitative microbial risk assessment (QMRA) to assess an existing sewage treatment plant (STP) at Roorkee, India. The midpoint LCA modeling revealed that high electricity consumption (≈ 576 kWh.day−1) contributed to the maximum environmental burdens. The LCA endpoint result of 0.01 disability-adjusted life years per person per year (DALYs pppy) was obtained in terms of the impacts on human health. Further, a QMRA model was developed based on representative sewage pathogens, including E. coli O157:H7, Giardia sp., adenovirus, norovirus, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The public health risk associated with intake of pathogen-laden aerosols during treated water reuse in sprinkler irrigation was determined. A cumulative health risk of 0.07 DALYs pppy was obtained, where QMRA risks contributed 86 % of the total health impacts. The annual probability of illness per person was highest for adenovirus and norovirus, followed by SARS-CoV-2, E. coli O157:H7 and Giardia sp. Overall, the study provides a methodological framework for an integrated LCA-QMRA assessment which can be applied across any treatment process to identify the hotspots contributing maximum environmental burdens and microbial health risks. Furthermore, the integrated LCA-QMRA approach could support stakeholders in the water industry to select the most suitable wastewater treatment system and establish regulations regarding the safe reuse of treated water.

소규모 하수처리장 유입 유량의 신뢰성에 관한 연구

To provide the basic data necessary to establish maintenance plans for existing sewage treatment plants in severely depopulated areas, the reliability of the inflow measurements for small-scale sewage treatment facilities was investigated. It was found that the population trends in sewage treatment districts and those in administrative districts did not coincide with each other, so the reliability of population-related data was very low. In addition, despite the low possibility of the inflow of water from unknown sources, more than 78% of the surveyed sewage treatment plants reported an inflow that was higher than the amount of tap water used within the treatment area. In particular, for sewage treatment plants with a capacity of 50 ㎥/day or less, the reliability of the flow rate measured using a flow meter installed in the sewage treatment plants was very low because the value calculated based on tap water consumption ranged from about 25% to 120% of the flow rate measured by the flow meter. These results indicate that, in small-scale sewage treatment plants where the reliability of the flowmeter is questionable, it is important to estimate the inflow rate based on the tap water consumption within the treatment area.

Practice and Research on Upgrading and Renovation of Sewage Treatment Plant in Guangxi Province

The construction of sewage treatment plant upgrading and renovation projects often needs to be completed under the conditions of ensuring the normal operation of existing sewage treatment plants. The renovation construction process is complicated, and the management and coordination are difficult. Taking the upgrading and renovation project of A sewage treatment plant in N City, Guangxi as the background, the problems faced in the process of upgrading and renovation of sewage treatment plant were analyzed, and reasonable and feasible solutions and management measures were put forward. certain reference value.

Peculiarities of formation of water quality of surface sources of water supply as a factor of a choice of a method of water treatment

The current state and formation of water quality in reservoirs that serve as sources of drinking water supply were considered. It was revealed that phytoplankton becomes one of the main factors influencing the formation of water quality in reservoirs in the warm period from June to November, especially during the period of reservoirs “blooming”. Mostly these processes are triggered by the explosive development of blue-green algae (cyanobacteria). The factors accompanying this phenomenon are shown. The characteristic of the influence of global climate change and new composition of wastewater on water quality in surface water supply sources is given. If earlier the sewage contained significant volumes of heavy metals, oil products, phenols, etc., now they are observed to decrease at several times and vice versa - an increase in the volume of biogenic compounds, especially phosphates is observed. The emergence of phosphates is caused both by the ingress of phosphate fertilizers into water bodies, and by household reasons - the massive distribution of phosphate-based detergents and the inability of existing sewage treatment plants to efficiently process them. Screening monitoring of the Dnieper river basin showed extremely high levels of the predicted safe concentration of herbicides, insecticides, fungicides, as well as pharmaceutical substances such as carbomazepine, lopinavir, diclofenac, efavirenz, etc. in water.
 That is, among organic pollutants, the focus changes from classic petrochemical products to the products related to agricultural and pharmaceutical production, which, in certain concentrations, can stimulate the development of phytoplankton.
 The effective methods for treating surface water in modern conditions are as follows:
 - physical retention of coarse fractions of phytoplankton using new designs of water intake structures;
 - the use of new filter materials that effectively trap finely dispersed phytoplankton fractions at the main treatment facilities and are capable of regenerating the filter media;
 - the use of new oxidizing agents-disinfectants that do not form toxic organochlorine compounds, with preliminary extraction of phytoplankton masses;

Biocrude Oil Production by Integrating Microalgae Polyculture and Wastewater Treatment: Novel Proposal on the Use of Deep Water-Depth Polyculture of Mixotrophic Microalgae

Microalgae have attracted significant attention worldwide as one of the most promising feedstock fossil fuel alternatives. However, there are a few challenges for algal fuels to compete with fossil fuels that need to be addressed. Therefore, this study reviews the R&D status of microalgae-based polyculture and biocrude oil production, along with wastewater treatment. Mixotrophic algae are free to some extent from light restrictions using organic matter and have the ability to grow well even in deep water-depth cultivation. It is proposed that integrating the mixotrophic microalgae polyculture and wastewater treatment process is the most promising and harmonizing means to simultaneously increase capacities of microalgae biomass production and wastewater treatment with a low land footprint and high robustness to perturbations. A large amount of mixotrophic algae biomass is harvested, concentrated, and dewatered by combining highly efficient sedimentation through flocculation and energy efficient filtration, which reduce the carbon footprint for algae fuel production and coincide with the subsequent hydrothermal liquefaction (HTL) conversion. HTL products are obtained with a relatively low carbon footprint and separated into biocrude oil, solid, aqueous, and gas fractions. Algae biomass feedstock-based HTL conversion has a high biocrude oil yield and quality available for existing oil refineries; it also has a bioavailability of the recycled nitrogen and phosphorus from the aqueous phase of algae community HTL. The HTL biocrude oil represents higher sustainability than conventional liquid fuels and other biofuels for the combination of greenhouse gas (GHG) and energy return on investment (EROI). Deep water-depth polyculture of mixotrophic microalgae using sewage has a high potential to produce sustainable biocrude oil within the land area of existing sewage treatment plants in Japan to fulfill imported crude oil.

Spatial patterns and influencing factors of sewage treatment plants in the Guangdong-Hong Kong-Macau Greater Bay Area, China

Over the past few years the discharge of waste and sewage in the Guangdong-Hong Kong-Macau Greater Bay Area (GHMB) of China has increased, exerting a great amount of pressure on ecological protection. In this study, we focus on achieving a balanced spatial layout of sewage treatment plants in order to reveal the regional differences and spatial patterns of sewage treatment plants in the GHMB and identify the key factors influencing the spatial patterns. In particular, we employ POI (point of interest) geographical data to evaluate the spatial patterns and agglomeration status of sewage treatment plants in the GHMB using Exploratory Spatial Data Analysis (ESDA). We then explore the principle influencing factors of the determined spatial patterns using the geographical weighted regression model (GWR). Results demonstrate that: (1) the absolute number of sewage treatment plants is highest in the central and western regions, while the per capita of sewage treatment plants is clearly clustered in the northwest and southwest regions; (2) the absolute number of sewage treatment plants exhibits larger spatial dissimilarity than that of the per capita values, with High-High cluster types principally distributed in the conjunction areas of Jiangmen, Foshan and Zhaoqing in western GHMB and Low-Low clusters in the western Pearl River Delta (PRD) estuary; and (3) the key influencing factors are identified as GDP per capita, the output value of the primary and secondary industries and industrial water consumption. Regions with high regression coefficient fluctuations of the four influencing factors are centralized within the PRD estuary and adjacent regions. Policy recommendations including optimizing the sewage treatment plant layout, enhancing the service capacity potential of the existing sewage treatment plants and upgrading the industrial structure are proposed to promote a spatial equilibrium configuration of sewage treatment plants in the GHMB.

Preliminary Investigation of an Installed Pilot-Scale Biological Nutrient Removal Technology (BNRT) for Sewage Treatment

Water utilities, commercial and industrial establishments are required to upgrade or install new treatment systems to comply with the revised effluent standards issued by the Department of Environment and Natural Resources – Environment Management Bureau (DENR – EMB) which now includes removal and monitoring of nutrients (nitrogen and phosphorus components). One solution is to utilize a biological nutrient removal technology (BNRT) system capable of removing nutrients from sewage. The on-going study aims to investigate the performance of the pilot-scale system in the removal of nutrients from sewage. The designed pilot-scale anaerobic-anoxic-oxic (A2O) process with a total hydraulic retention time of 8.37 hrs. was operated in an existing sewage treatment plant (STP). System modification was adapted to ensure continuous operation. Dissolved oxygen (DO) and temperature of each compartment were evaluated after 45 days of system modification. The DO of the anaerobic and oxic compartment remained within the required range, while the internal recycling flowrate and/or aeration must be adjusted to achieve a DO concentration of 0.20 – 0.50 mg/L in the anoxic compartment. The research is financially supported by the Philippine Council for Industry, Energy and Emerging Technology Research and Development of the Department of Science and Technology (PCIEERD Project No. 04176).

Study of the Efficiency of Sludge Conditioning by the Method of Advanced Oxidation Process (AOP) During Dewatering of Excess Activated Sludge

The issue of sludge disposal is a complex task that needs to be addressed, taking into account not only economic indicators but also local conditions, such as: the availability of existing sewage treatment plant infrastructure, energy availability, climatic conditions and so on. Currently, more and more municipal enterprises in European countries are building sludge incineration plants. Preparation of sludge for incineration occupies a significant part of the budget since its humidity and caloric content have the greatest impact on the parameters of the sludge incineration unit and its energy balance. Chamber-membrane filter presses are one of the few types of equipment that allows to ensure the maximum reduction of sludge moisture, and the possibility of its completion with heat treatment systems in one closed housing make it an even more attractive solution for small and medium wastewater treatment plants. Of great interest at the present stage of development of wastewater treatment and sludge disposal technology is the technology of advanced oxidation of AOR, which allows to remove biologically stable organic pollutants and leads to inactivation of pathogenic microorganisms. The purpose of this stage was to evaluate the possibility of using the technology of advanced oxidation of AOP for conditioning sludge of municipal treatment plants before their mechanical dehydration and to determine the technological parameters of the sludge filtration process. The studies included laboratory and industrial tests. Based on the research, it was found that AOP technology can be used to reduce the consumption of reagents (iron, lime) in the conditioning of municipal sewage sludge in the case of filtration on a chamber-membrane filter press. The most economically and technologically optimal ratio of Fe / Ca / H2O2 is equal to 2/5/1 at the dosage of hydrogen peroxide H2O2 at the level of 1 g / l. At the proposed dosages of reagents, it is possible to obtain a filtration sludge with a residual moisture content of 64–65% compared to 72–73% using only iron and lime (initial dry matter content in the sludge at 3%).

Application of Decision Making Tool to Determine Effluent Quality Index of Existing Sewage Treatment Plants

Water is one of the most essential resources for living and is utilized for different purposes including domestic, industrial, and agricultural and other such applications. The water supplied from city municipalities is primarily used for domestic purposes with about 80% of the supplied water being considered as being generated into wastewater. The scarcity of water in different parts of the world and particularly in developing countries has led to potential reusability of the generated wastewater. However, the reusability of the generated wastewater is significantly dependent on the efficiency of the treatment plants for the treated effluent to be deemed fit for different applications. The efficiency of the existing sewage treatment plant can be determined using the parameter effluent quality index (EQI). It is an important tool which tells the quality of effluent generated by the treatment plants and hence it’s potential for reuse for different purposes. It is determined by assigning suitable weightage to different parameters of wastewater for determining the final effluent quality. As such, this paper uses EQI approach to evaluate existing sewage treatment plants in Himachal Pradesh.

Foundation Design and Construction Challenges with Marsh Deposits in a High Seismic Risk Zone

Driven piles are ideal for supporting structures over very soft ground, especially in high seismic risk zones. Challenges include achieving sufficient vertical and lateral load capacities within the constraints of pile spacing and geologic conditions. Through a unique case study, the authors will describe the process of site exploration, foundation selection, pile design, and installation of over 3,000 concrete piles in a small 4.5-acre (1.8 hectare) site (average of one pile per 65 square feet). A state-of-the-art, $180 million plant for biosolids processing, biogas management and energy recovery was sited in marshland next to an existing sewage treatment plant. The new construction included a 70-foot (21 m) tall building and three closely spaced, 90-foot (27 m) high, 65-foot (20 m) diameter, egg-shaped steel digester tanks. The site, classified as class “F”, was underlain by up to 45 feet (14 m) of highly compressible peat and organic clays, below which was a dense sand and gravel layer. The groundwater was very shallow and site-specific seismic hazard analyses were required. Particularly challenging was achieving the needed lateral resistance to seismic loads in the very weak clay and peat deposits. The project was instructive of the importance of adequate characterization of geologic conditions even in small sites; the necessary iterative collaboration process between geotechnical and structural engineers; and the value of a well-designed indicator pile program. The test pile program allowed for refining (shortening) the design pile lengths for considerable cost savings and reduced installation time. Of interest to the reader will be the surprising depth to refusal for some areas of the site, despite the test pile program.

ВДОСКОНАЛЕННЯ ТЕХНОЛОГІЇ ОЧИЩЕННЯ СТІЧНИХ ВОД ФАРБУВАЛЬНО-ОЗДОБЛЮВАЛЬНОГО ВИРОБНИЦТВА ШЛЯХОМ ВПРОВАДЖЕННЯ ПРОЦЕСІВ КАВІТАЦІЇ Й ЕЛЕКТРОАКТИВАЦІЇ ТА МОЖЛИВОСТІ ПОВТОРНОГО ВИКОРИСТАННЯ СТІЧНИХ ВОД

The problem of sewage treatment with the content of organic dyes is urgent now. Existing dyeing and finishing textile industries are not efficient and highly profitable. Wastewater enters a large number of unused dyes, which cause significant damage to the ecological system of the water region. That is why the problem of reuse of wastewater in technological processes of textile production (dyeing of fabric) and deep purification of wastewater of this production is urgent. The article presents the results of the analysis of sewage dyeing and finishing textile production after averaging and dilution, as well as production sewage immediately after the fabric dyeing process (at the outlet of the dyeing plant). Based on the obtained results, the technology of wastewater treatment of dyeing and finishing production containing organic dyes is proposed, using the processes of filtration, coagulation and flocculation in the cavitator, flotation and electroactivation for the development of effective technology of water cycle and reuse of industrial processes textile production. The results of sewage research are obtained at the cascade type pilot plant, the stages of which have been located above the sump of the existing sewage treatment plant. The analysis of sewage at the outlet of the dyeing plant allows to predict the creation of promising technology for the conversion of industrial wastewater into a state suitable for reuse in the technological cycle of dyeing fabrics. Having implemented such technology in practice, the problem of minimizing the cost of expensive dyes, reducing the cost of textile products while maintaining its quality, as well as reducing the environmental hazard of waste in the form of wastewater is solved.

Performance evaluation and upgrade options for existing sequencing batch reactor for nutrient removal

Assessment and upgrade of existing sewage treatment plants (STPs) are necessary due to the revision of the existing effluent regulations which now monitors nutrients including ammonia, nitrate and phosphates. The aim of this study is the performance evaluation of four sequencing batch reactor (SBR) type of STP based on the following parameters: biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), nitrates, ammonia, phosphates and pH; and their potential upgrade based on the revised regulations stated in DAO 2016-08. Four sequencing batch reactor (SBR) type of STP were assessed for 12 weeks for this study. Results showed noncompliance with nutrient levels, thus upgrade is necessary. Analytical Hierarchy Process (AHP), a Multi-Criteria-Analysis (MCA) tool, was used to select the best option for upgrade among options that include (1) additional SBR tank, (2) diverting wastewater to another treatment facility, and (3) converting the SBR into membrane bioreactor (MBR). Considering the criterion for upgrade, option 2 was the most preferred decision followed by option 1 then option 3.

In-vessel co-composting – a rapid resource recovery option for septage treatment in Indian cities

Abstract Septage management is a challenging task across India as more than 44% of the population depends on septic tanks for human waste management. Septage collected from Chennai city, India, was found to be rich in nutrients even though the total solids content (<2%) and C/N are low. The current practice of septage disposal in Chennai city is co-treatment in existing sewage treatment plants. The main drawback of this method is that treatment efficiency could deteriorate if the organic load increased much beyond the design load of the treatment plant and would result in poor treated-water quality. In this context, the present study focused on the potential of in-vessel co-composting as a sustainable treatment option. In order to enhance the co-composting process, suitable co-substrates were identified for making the process efficient and cost-effective. The area under the temperature profile during composting was used as an assessment tool for the identification of the proper mix. Addition of mixed organic waste and coir pith waste (bulking agent) to the dewatered septage gave the highest area among the different combinations. Different waste combinations were investigated in order to assess the suitability for field scale application.

Groundwater contamination by sewage causes benthic algal outbreaks in the littoral zone of Lake Baikal (East Siberia)

Abstract Lake Baikal, an ancient lake in Siberia, contains more endemic species than any other lake in the world with most of them residing in the benthic littoral zone. Explosive growth of benthic Spirogyra, a filamentous green alga, began approximately in 2011 in localized coastal areas, with the most severe examples occurring near coastal towns that lack a wastewater treatment facility or have a malfunctioning system. At other sites (small settlements, harbors), however, the cause of its excess growth is less obvious. Multiple hypotheses have been offered including lake level fluctuations, climate warming, a relaxation of grazing pressure, and coastal eutrophication. We assessed these hypotheses using data on historical lake levels, water temperature, the spatial-temporal distribution of Spirogyra along inhabited and non-inhabited shorelines, and measurements of fecal coliform bacteria and nutrients in ground water, interstitial water, and lake water. These data suggest that groundwater contamination is the primary cause of coastal eutrophication. Most houses and buildings in small settlements around Lake Baikal lack septic tanks but use unlined cesspools to collect human waste. This untreated human waste enters groundwater via passive filtration through permeable soils and flows to the coastal zone where it drives excess growth of Spirogyra. Remediation — including installation of septic systems, modernization of existing sewage treatment plants in coastal towns, and the adoption of non-phosphate containing detergents — as well as a reconsideration of the federal monitoring system regarding the coastal zone is urgently needed to protect this extraordinary lake.