Central Treatment Plant Research Articles

Equity-centered adaptive sampling in sub-sewershed wastewater surveillance using census data.

Sub-city, or sub-sewershed, wastewater monitoring for infectious diseases offers a data-driven strategy to inform local public health response and complements city-wide data from centralized wastewater treatment plants. Developing strategies for equitable representation of diverse populations in sub-city wastewater sampling frameworks is complicated by misalignment between demographic data and sampling zones. We address this challenge by: (1) developing a geospatial analysis tool that probabilistically assigns demographic data for subgroups aggregated by race and age from census blocks to sub-city sampling zones; (2) evaluating representativeness of subgroup populations for COVID-19 wastewater-based disease surveillance in Davis, California; and (3) demonstrating scenario planning that prioritizes vulnerable populations. We monitored SARS-CoV-2 in wastewater as a proxy for COVID-19 incidence in Davis (November 2021-September 2022). Daily city-wide sampling and thrice-weekly sub-city sampling from 16 maintenance holes covered nearly the entire city population. Sub-city wastewater data, aggregated as a population-weighted mean, correlated strongly with centralized treatment plant data (Spearman's correlation 0.909). Probabilistic assignment of demographic data can inform decisions when adapting sampling locations to prioritize vulnerable groups. We considered four scenarios that reduced the number of sampling zones from baseline by 25% and 50%, chosen randomly or to prioritize coverage of >65-year-old populations. Prioritizing representation increased coverage of >65-year-olds from 51.1% to 67.2% when removing half the zones, while increasing coverage of Black or African American populations from 67.5% to 76.7%. Downscaling had little effect on correlations between sub-city and centralized data (Spearman's correlations ranged from 0.875 to 0.917), with strongest correlations observed when prioritizing coverage of >65-year-old populations.

Urban wastewater management in Nepal: generation, treatment, engineering and policy perspectives

ABSTRACT Rapid urbanization has caused a worldwide increase in the discharge of wastewater effluent. Although Nepal has a noteworthy history of wastewater management, progress in this field has been hindered by persistent issues. These problems encompass insufficient sewer coverage, deficient treatment and sludge disposal facilities, inadequate treatment infrastructure, lack of coherent institutional frameworks, and a lack of comprehensive planning. This review provides a glimpse into Nepal's current urban wastewater landscape while also offering a concise historical overview of its wastewater management trends. The study gathered data, information from government organizations, as well as related research, review articles, and reports from 1999 to 2023. Our findings reveal that more than 85% of urban households in Nepal rely on onsite sanitation, with limited access to septage treatment facilities. The ratio of wastewater treatment to generation is disconcertingly low, further emphasized by the concentration of centralized treatment plants in the capital city. This low ratio underscores the inadequacy of the existing wastewater system and the novice approaches of the government, which contribute to the poor sewerage facilities in Nepal. This study unequivocally highlights the imperative need for functional and institutional hierarchy emphasizing local communities, substantial changes in resource allocation, governance practices, and technical infrastructure.

Techno-Economic Assessment of Anaerobic Digestion for Olive Oil Industry Effluents in Greece

Olive mill wastes are some of the most important waste streams in Mediterranean countries, such as Greece, and their uncontrolled disposal without treatment imposes serious environmental impacts. In the last few decades, the European Union has defined the framework for a sustainable circular economy, aiming for viable waste treatment solutions. Under this scope, anaerobic digestion could be a remarkable solution for efficiently reducing waste organic matter and producing green energy, at the same time. In this study, the economic sustainability of an anaerobic digestion unit for olive mill effluents was assessed. It was found that a centralized treatment plant that can process liquid olive mill effluents during the olive harvesting season and other agro-industrial by-products (such as fruit and vegetable waste) for the rest of the year could be a viable solution, with waste capacities of 780 m3OMW d−1 and 245 kgFVW d−1. The internal rate of return was estimated at 6%, the net present value was estimated to be EUR 2 million, while the payback period was calculated to be 12 years. Furthermore, through the sensitivity analysis, the selling price of the electricity produced and the productivity of the waste processed in the plant alongside the olive mill wastewater were identified as the main factors affecting the viability of the process. The findings of this study can be applied in the development of a biomass-processing facility, taking into consideration the economic feasibility and the processing of challenging-to-treat wastes to generate green energy.

Assessment of surface water quality using the Water Quality Index (WQI) and multivariate statistical analysis (MSA), around tannery industry effluent discharge areas

Abstract The study attempted to assess the water quality around the tannery effluent discharge areas for suitability for irrigation purposes using different indices (Water Quality Index (WQI)) and statistical analysis in Savar Upazilas, Dhaka, Bangladesh. The samples were collected three times, from monsoon 2021 to pre-monsoon 2023. The analysis results showed that the concentrations of various parameters at most of the sampling points exceeded the surface water standard. Pollution levels were found in the following order: pre-monsoon, post-monsoon, and monsoon. At SW1 point, the CWQI, WWQI, and MWQI of the surface water quality showed a ‘poor’ category. The IWQI values showed that the surface water at all the sampling points was suitable for irrigation purposes, except for the SW1 sampling point. The NPI indicates that EC, BOD, COD, TSS, Cl−, Na+, and NO3--N parameters were potentially responsible for polluting most sampling sites. Multivariate statistical analyses like principal component analysis, cluster analysis, and Pearson correlation matrix showed significant anthropogenic intrusions of these variables in surface water in the area. A strong correlation between these parameters indicated their common origin, i.e., poorly treated tannery industry effluent entered the surface water, suggesting an improvement in the efficiency of the Central Effluent Treatment Plant (CETP).

A decision support model to investigate the pandemic recovery challenges and strategies in the leather supply chain

AbstractThe COVID-19 has caused unprecedented disruptions to supply chains (SC) worldwide, posing numerous challenges for industries, particularly in the emerging economies (EE). These economies are undergoing a phase of recovery from the pandemic devastations now, requiring investigation into the recovery challenges (RCs) and propositions for effective recovery strategies (RSs) to address RCs. Given this backdrop, this study aims to explore the COVID-19-related RCs in the Bangladeshi leather industry and build an integrated decision-making model to formulate RSs to counteract the RCs while the industry seeks to recover. This study used Pareto analysis to deduce lists of the nine most critical RCs and nine vital RSs for the Bangladeshi leather industry. This study also applied the best worst method (BWM) to identify a long-term liquidity crisis and an increasing bankruptcy of business stakeholders as the most urgent RCs, highlighting financial sustainability as a significant matter of concern for the sector. With regard to the RSs, the application of the fuzzy Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) indicated a need to solve the existing problems of central effluent treatment plant (CETP) and provisioning of solid waste management facilities for long run business as priorities to make the leather industry SC more financially and operationally sustainable. The RSs formulated in this study have managerial implications for decision-makers in reducing the adversities caused by the pandemic and hence improving the SC performance of the leather industry. Although not totally, these valuable insights into the RCs and RSs for the leather industry during and following COVID-19 periods can be generalized across other industries in Bangladesh and EE regions affected by the pandemic.

Leachate management in medium- and small-sized sanitary landfills: a Greek case study

The sustainable management of landfill leachates remains a matter of important concern in many countries. We used as case study a medium-sized Greek landfill, and we initially investigated the performance of the existing secondary leachate treatment system. The activated sludge process removed chemical oxygen demand (COD), biochemical oxygen demand (BOD), NH4-N, and PO4-P by 55%, 84%, 94%, and 14%, respectively, but the effluents did not meet the legislation requirements for discharge or reuse. Afterwards, different management options of these effluents (co-treatment with sewage in the centralized treatment plant, onsite tertiary treatment with reverse osmosis, granular activated carbon (GAC), ozonation, photo-Fenton, or constructed wetlands) were evaluated regarding their operational costs and environmental footprint. The use of constructed wetlands presented the lower operational cost, energy requirements, and greenhouse gas (GHG) emissions, not exceeding 21.5 kg CO2eq/day. On the other hand, the power consumption and the GHG emissions of the other on-site technologies ranged from 0.37 kWh/m3 and 5.56 kg CO2eq/day (use of GAC) to 39.19 kWh/m3 and 588.6 kg CO2eq/day (use of ozonation), respectively. The co-treatment of the leachates with municipal wastewater required 0.6 kWh/m3 and emitted 30.18 kg CO2eq/day. For achieving zero-discharge of the treated leachates, a system consisting of constructed wetlands and evaporation ponds in series was designed.

Evaluation of effects of wastewater on socio-economic activities of residents in Kano Metropolis, Kano State, Nigeria

The paper assessed the effects of wastewater on socio-economic activities of residents in Kano metropolis, Kano State, Nigeria. High population, poor drainage channels and lack of central wastewater sewerage and functional treatment plants have necessitated indiscriminate discharge of wastewater into the environment. Using Krejcie and Morgan (1970) table for determining sample size, a total of 384 population size was sampled and purposefully, systematically and randomly administered questionnaires in Likert Scale Format. Interviews were also conducted with stakeholders and community elders and direct filed observation for elucidation of the socioeconomic effects of wastewater. Results were presented in tables and charts and further expressed in strength of associations using Spearman rho statistics analysis. Findings show that 89.75% of respondents are of the view that wastewater from households and commercial areas is let loose into the environment and affects land-use as well as domestic activities. It also shows that 88.5% reported that wastewater affects the means of livelihood of residents and 92.19% opined that economic cost of construction of drainage channels, embankment and sandbags while 92.5% strongly and agreed that wastewater affects the health of the residents and causes different kinds of diseases. The study further shows that wastewater has effect on businesses and recreations while making some places inaccesible and affectng their economic activities. The study therefore recommends public enlightenment, strong legislations and enforcement of principle of polluter pays, attitudinal change and population decongestion, centralized sewerages system should be implemented among others should strictly be adhered to harness to encourage socio-economic activities.

Chlorella vulgaris has been used in the biological treatment of some pollutants and heavy metals in municipal wastewater

This study aims to prove the ability of Chlorella vulgaris to treat some pollutants such as nitrates, nitrites, phosphates, ammonia, the chemical oxygen requirement and some heavy metals such as cadmium and copper present in the water of municipal wastewater treatment plants. Water samples were taken from Al-Rumaitha Central Water Treatment Plant, Al-Muthanna Governorate, Iraq. Contaminated water was added to the algal culture after the algae reached the Stationary phase after 10 days of growth. The tests were performed on the water after two periods, the first after 4 days of the algae reaching the Stationary phase and the second after 8 days before the arrival of the algae to the Death phase. The results showed a high efficiency of Chlorella vulgaris in treating polluted water. The removal percentage after 4 days of exposure period was as follows: BOD5 86.6%, nitrate 62.9%, nitrite 14.7%, ammonia 94.2%, and phosphate 86.2%. As for the heavy elements, they were as follows: copper 98.9%, cadmium 94.75%. After 8 days of the treatment process, the efficiency of the algae was better than the previous days, where the results showed the following removal percentages, BOD5 88.4%, nitrate 63.7%, nitrite 23%, ammonia 97.9%, phosphate 87.3%. As for heavy metals, the percentages were as follows: copper 99.2%, cadmium 97.9%. The results of this study showed the efficiency of Chlorella vulgaris in the treatment process and its high ability to remove pollutants from water, especially nutrients and heavy metals, and green algae is a promising, highly efficient and environmentally friendly biological treatment technology. Keywords: heavy metals, Chlorella vulgaris, wastewater

Impacts of seasonal variations and wastewater discharge on river quality and associated human health risks: A case of northwest Dhaka, Bangladesh

Surface water pollution caused by the discharge of effluents from industrial estates has become a major concern for Dhaka (Bangladesh). This study aims to have a concise look at the severe river water pollution, mainly from effluents discharged from the tannery village. Effluent samples were collected from five ejected points, including the central effluent treatment plant (CETP), twenty adjacent river water, and two pond water nearby Hemayetpur, Savar. Thirty-one parameters have been observed at these sampling points for three seasons, from April 2021 to January 2022. The results obtained from water quality indices, i.e., water quality index (WQI), entropy water quality index (EWQI), and irrigation water quality index (IWQI), show that most studied surface water samples ranked “unsuitable” for consumption, irrigation, and anthropogenic purposes. The highest health risk was observed downstream of Hemayetpur city at the Savar CETP discharge site, indicating higher levels of heavy metal in the river water following the tannery village. Carcinogenic and non-carcinogenic human health risks could be triggered mainly by water consumption as concentrations of arsenic (As), chromium (Cr), nickel (Ni), and lead (Pb) exceeded the upper benchmark of 1 × 10−4 for adults and children. The results of the carcinogenic risk assessment revealed that children were more vulnerable to health hazards, and quick corrective action is required to control the increased levels of heavy metals at all sample locations. Therefore, through bioaccumulation, human health and the environment are affected in these areas. Using river water for consumption, household work, or even irrigation purposes is not advisable. This study's result highlighted that properly implementing compatible policies and programs is required to improve effluent treatment methods and provide biodegradability to the Dhaleshwari River.

Environmental and economic assessment of the construction, operation, and demolition of a decentralized composting facility

Decentralized waste treatment facilities are recently highlighted for the treatment of solid waste in rural areas for being cheap, flexible, and reliable. Among them, decentralized composting is most commonly used. Many forms of decentralized composting facilities also develop and apply in developing countries, but the environmental and economical performances remain unknown. Therefore, this study analyzed the environmental impacts and cost of a decentralized composting facility through life cycle assessment and life cycle cost. The functional unit was the construction, operation, and demolition the composting facility. Contribution and sensitivity analysis were also performed to find out the most influential processes and parameters. The facility had a 10-year designed life span and could treat about 5840 t organic waste in its life cycle. The life cycle environmental impacts were 646,700 kg CO2-eq, 8980 kg SO2-eq, −28 kg P-eq, 7.09 × 10−3 CTUh, 0.13 CTUh, and 16,754 kg oil-eq for climate change, terrestrial acidification, freshwater eutrophication, human toxicity cancer effects, human toxicity non-cancer effects, and fossil resources scarce, respectively. The life cycle cost was 1080.925 k CNY. When scaling to treating 1 t organic waste, the environmental impacts were close to those of similar decentralized and centralized composting facilities and the cost was lower than those of centralized biological treatment plants when excluding revenues from compost. According to the contribution and sensitivity analysis, the operation stage had the largest environmental impacts. The composting and compost substitution processes in the operation stage were the most sensitive processes. This study proved quantitatively that the decentralized facility was feasible both environmentally and economically and enriched the study cases for decentralized composting facilities.

Characterization of Tannery Effluent and Efficiency Assessment of Central Effluent Treatment Plant (CETP) at Savar in Bangladesh

The industry discharges a large volume of effluent, many of which contain lots of chemicals and toxic substances that have the potential to cause distress to the environment. The study focused on analyzing various physicochemical parameters of the effluent discharge from the Central Effluent Treatment Plant (CETP) at the Savar Tannery Industrial Zone. The effluent was collected four times (pre-monsoon, monsoon, and post-monsoon) a year, from 2021-2022. The effluent was inspected for vital water quality parameters, such as pH, COD, BOD, TDS, TSS, NO3-, SO42-, HCO3-, PO43-, Cl-, Na, Ca, Cr, Fe, Cu, Zn, and Pb. Most of the parameters exceed the standard permissible limit of the Department of Environment, Bangladesh (DoE, BD), NQES, and ISW-BDS for inland water. The mean concentrations of COD, BOD, TSS, and Cr were 337, 97.5, 209, and 6.1 mg/L, and these values were far above the permissible limit with a removal efficiency of 51%. The study observed that industrial discharge of unproperly treated effluent deteriorates the surface water quality and causes huge threats to aquatic life and sustainable water resource management.

Characterization and Removal Efficiency of Central Effluent Treatment Plant (CETP)

Tannery industries are one of the most pollution-generating industries in the world. Tannery wastewater is usually characterized by high BOD, COD, TDS, and TSS and a high percentage of dissolved organic and inorganic matter. The central effluent treatment plant (CETP) of industry plays a vital role in sustainable industrial waste management and saves different lives from harmful effects. The study aimed to analyze various physicochemical parameters of the composite tannery influent and effluent as well as the removal efficiency of the CETP of the Savar Tannery Industrial Zone in Bangladesh. It was carried out at Savar Upazila, situated in the northwest part of Dhaka, Bangladesh. The samples were collected three times (pre-monsoon, monsoon, and post-monsoon) in a year, from monsoon 2021 to pre-monsoon 2022. The major water quality parameters for the influents and effluents included pH, BOD, COD, TDS, TSS, NO3-, SO42-, HCO3-, PO43-, Cl-, Na, Ca, Cr, Fe, Cu, Zn, and Pb. Most of the parameters, especially BOD, COD, TDS, and TSS after treatment, exceeded the standard permissible limits of effluent discharge prescribed by the ISW-BDS-ECR (1997), DoE-BD, and NEQS (2000), and these values were two times higher than the permissible limit. The DO value was four times lower than the permissible limit, indicating heavily polluted water. The concentration of the cations in the tannery effluents was in the following order: Na>Ca>Cr>Fe>Cu>Zn>Pb. The analysis results illustrated that the overall removal efficiency of the CETP was about 47%. The study observed that the performance of the CETP was not satisfactory, and hence it needs further improvement in the treating capacity for sustainable industrial wastewater management.

Industrial Water Demand and Wastewater Generation: Challenges for Bangladesh’s Water Industry

Bangladesh has experienced massive industrial growth in the past century. With the impressive industrial development, the country struggles to meet the demand for water and manage the wastewater generated. This paper critically analyzes Bangladesh’s three significant industrial wastewaters: textile, tannery, and landfill leachate. The textile and leather industries are major freshwater consumers and wastewater generators in Bangladesh. Most textile factories across Bangladesh operate without effluent treatment plants, causing severe water pollution. Unlike textile plants, most tanneries are located in Savar, Dhaka. Savar’s newly constructed central effluent treatment plant has serious design flaws and cannot meet discharge standards. Bangladesh has only three sanitary landfills for municipal solid waste disposal. With inadequate leachate collection and treatment facilities, the landfills have become point sources of surface water and groundwater pollution. The pollution of water resources is devastating as Bangladesh depends on surface water for irrigation and groundwater for drinking. Although Bangladesh has mandated laws and regulations for water pollution control, the lack of implementation is a significant problem. To get a better handle on industrial water demand and wastewater treatment, the Bangladesh government and the Department of Environment should work together to implement stricter laws and regulations and emphasize technical workforce development and stakeholder training.

The feasibility of SARS-CoV-2 surveillance using wastewater and environmental sampling in Indonesia.

Wastewater-based epidemiology (WBE) surveillance as an early warning system (EWS) for monitoring community transmission of SARS-CoV-2 in low- and middle-income country (LMIC) settings, where diagnostic testing capacity is limited, needs further exploration. We explored the feasibility to conduct a WBE surveillance in Indonesia, one of the global epicenters of the COVID-19 pandemic in the middle of 2021, with the fourth largest population in the world where sewer and non-sewered sewage systems are implemented. The feasibility and resource capacity to collect samples on a weekly or fortnightly basis with grab and/or passive sampling methods, as well as to conduct qualitative and quantitative identification of SARS-CoV-2 ribonucleic acid (RNA) using real-time RT-PCR (RT-qPCR) testing of environmental samples were explored. We initiated a routine surveillance of wastewater and environmental sampling at three predetermined districts in Special Region of Yogyakarta Province. Water samples were collected from central and community wastewater treatment plants (WWTPs), including manholes flowing to the central WWTP, and additional soil samples were collected for the near source tracking (NST) locations (i.e., public spaces where people congregate). We began collecting samples in the Delta wave of the COVID-19 pandemic in Indonesia in July 2021. From a 10-week period, 54% (296/544) of wastewater and environmental samples were positive for SARS-CoV-2 RNA. The sample positivity rate decreased in proportion with the reported incidence of COVID-19 clinical cases in the community. The highest positivity rate of 77% in week 1, was obtained for samples collected in July 2021 and decreased to 25% in week 10 by the end of September 2021. A WBE surveillance system for SARS-CoV-2 in Indonesia is feasible to monitor the community burden of infections. Future studies testing the potential of WBE and EWS for signaling early outbreaks of SARS-CoV-2 transmissions in this setting are required.

Finding the best combination of autochthonous microorganisms with the most effective biosorption ability for heavy metals removal from wastewater.

The presence of heavy metals (HMs) in the environment represents a serious environmental problem. In this regard, this work was conceived with the aim of finding, among indigenous microorganisms, the species and their combinations with the best biosorption activity for the following HMs: zinc, lead, cadmium, copper, and nickel. The experiment was carried out in several steps: (1) isolation and identification of microbial strains from the Central Effluent Treatment Plant’s wastewater; (2) studying the interaction of microorganisms and the ability to form biofilms in 96-well plates; (3) testing the resistance of biofilms to HMs; (4) testing the growth of biofilms on AMB media carriers in the presence of HMS; and (5) biosorption assay. The selected strains used in this study were: Enterobacter cloacae, Klebsiella oxytoca, Serratia odorifera, and Saccharomyces cerevisiae. The best biofilm producers in control medium were K. oxytoca/S. odorifera (KS), followed by K. oxytoca/S. odorifera/S. cerevisiae (KSC), and E. cloacae/K. oxytoca/S. odorifera (EKS) after 10 days of incubation. Mixed cultures composed of three species showed the highest resistance to the presence of all tested metals. The best biosorption capacity was shown by KSC for Cu2+ (99.18%), followed by EKS for Pb2+ (99.14%) and Cd2+ (99.03%), K. oxytoca for Ni2+ (98.47%), and E. cloacae for Zn2+ (98.06%). This research offers a novel approach to using mixed biofilms for heavy metal removal processes as well as its potential application in the bioremediation of wastewater.

Integrated Design and Optimization of Water-Energy Nexus: Combining Wastewater Treatment and Energy System

Designing more sustainable urban infrastructure is an essential topic in practice and research. While many have tried to address this challenge by focusing on sustainability of either supply or demand in a single infrastructure system, few studies have integrated the decisions for both supply and demand across several infrastructure. This paper proposes a novel method to design and optimize the hourly demand and supply of integrated energy and water system in an urban district for environmental and economic sustainability. This modular framework concurrently designs the optimal building mix of an urban district and the systems supplying the district with wastewater treatment, cooling, heating, and electricity. The model is tested on a sample neighborhood from San Francisco, California, with 21 building prototypes, 32 combined heating and power engines, 16 chillers, and 3 wastewater treatment systems (a central treatment plant and two decentralized membrane-based systems). The results of this study show that the median values of normalized life-cycle cost, social cost of carbon, annual energy demand, and annual wastewater production of the integrated designs of water-energy system are, respectively, 20, 75, 8, and 20% lower than those of the traditional segregated designs. The results also demonstrate the economic and environmental viability of using decentralized advanced treatment in urban areas when energy system, wastewater treatment, and building mix are designed together.

AN ANALYSIS ON THE LEATHER INDUSTRY OF BANGLADESH: IDENTIFICATION OF BARRIERS, CHALLENGES, AND WAY OUTS

The leather industry of Bangladesh has huge potential. Despite the availability of raw skins, low-cost labor, and the fact that this sector began a few decades ago, it has not evolved to its full potential. Furthermore, this sector's performance is deteriorating. The main purpose of this study is to explore the major causes behind such a downturn and also try to point out the major barriers, challenges, and make suggestions for combating these challenges. The data acquired via a questionnaire from officials of 45 different companies were reviewed by the researcher in order to achieve these objectives. In analyzing and making interpretation simple tabular along with graphical methods have been employed. The majority of participants gave positive replies when it came to the availability of high-quality indigenous raw hides, low-cost efficient labor, electricity, gas, and water supplies. Respondents had negative attitudes toward the availability of indigenous sub-materials and chemicals, infrastructural development in accordance with international standards, the Central Effluent Treatment Plant (CETP), the existence of an appropriate integrated plan, and the use of sophisticated technology, among other things. The study's last section outlines the significant limitations/barriers, challenges/threats, and recommendations for overcoming these potential challenges in Bangladesh's leather sector. This section was created primarily from the responses to four descriptive questions in the questionnaire's lower section.
 Keywords: Leather industry, Relocation, CETP, LWG certification.

Industrial Symbiosis for Optimal Bio-Waste Management and Production of a Higher Value-Added Product

A considerable amount of food waste ends up in centralized treatment plants due to the lack of preventive measures, resulting in significant environmental impacts. Hospitality food waste management is even more resource-intensive because of animal by-products regulation. According to this regulation, companies must store and then consign waste to specific waste managers. The extensive need for transportation of high-moisture-content materials is the leading cause of the impact. Moreover, the management of category III animal by-products is costly for companies. A previous study has shown the economic benefits of decentralized animal by-product treatment by intensive composting in catering companies. Although the produced compost was characterized by exceptional quality parameters, it was phytotoxic. The investigation of hospitality waste management is scarcely discussed among scholars, and waste management on a regional scale is nearly absent. This study examines the regional management of hospitality food waste by exploiting the municipal waste management infrastructure and intensive composting at the source. The co-maturation experiment with animal by-products and municipal green waste primary composts showed that the phytotoxicity parameters of the cured compost were in the optimal range or below the thresholds (conductivity (1.1 mS cm−1), dissolved organic carbon (82 mg kg−1), and NH4+/NO3− ratio (0.0027)). Additionally, the amounts of total nitrogen, water-soluble nitrogen, and water-soluble phosphorus in the compost were rated as very high. Finally, inventory and environmental impact analysis of the current and planned management approaches showed a reduction in 12 of 18 impact categories.

A Simple Method for Identifying Appropriate Areas for Onsite Wastewater Treatment

Onsite Domestic Wastewater Treatment Systems (ODWTS) are increasingly important for treating domestic wastewater in metropolitan contexts, especially in suburban sectors isolated from sewer networks and centralized treatment plants. When ODWTS are not correctly planned and located in suitable places, or are not properly designed, they can cause groundwater contamination and generate risks for human health. This work presents a Spatial Decision Support System (SDSS) to zone specific areas based on a few simple parameters. The proposed tool can be easily adapted to different contexts, even where institutional capacities are low. Results obtained in the metropolitan area of the Lerma Valley (Salta, Argentina) show strong contradictions between our zoning and current urbanization features in the study area. As a result, environmental impacts and health hazards are likely to manifest in the short or medium term. The sectors with the best receptivity conditions were found in the southern sector of the study area. We argue that ODWTS can be safely implemented in many areas as long as this concept is embedded in urban planning initiatives, which usually also require the consolidation or development of appropriate institutions and control systems.

Assessing inter and intra-variation in the characteristics of faecal sludge from Vadgaon Maval, Maharashtra: For better faecal sludge management in India

Faecal Sludge (FS) produced in developing countries has become a significant source of water pollution. The optimal treatment of FS can lead to a sustainable economy. In India, the second phase of the open defecation free (ODF) initiative (energy recovery by providing city- or town-level centralised FS treatment plants) has begun from 2019 to sustain millions of toilets. However, to achieve this goal, India must address significant knowledge gaps such as the type of available on-site sanitation treatments (OSTs), optimal time of emptying the OSTs, and variations in the FS characteristics with age. Thus, the present study analysed FS samples collected from Vadgaon Maval, Maharashtra, India, to understand the inter- and intra-variation in FS characteristics. The pH, electrical conductivity, total solids (TS), specific gravity (SG), organic matter (OM), chemical oxygen demand (COD), and pathogen content of FS samples were observed to be in the range of 7–7.65, 1.19–4.01 mS/cm, 1–123 g/L, 0.88–1.26, 18.4%–100%, 960–6080 mg/L, and 105–109 number/L of FS, respectively. The inter-variation of FS characteristics exhibited that the pH, EC, TS, and SG increased, whereas OM, settling, and drying capacity decreased with an increase in age. Fresh FS (excreta degraded for ≤3 years) was yellowish-brown in colour and exhibited low TS, low SG, and high OM. On the other hand, older FS (excreta degraded for >3 years) was blackish-brown in colour and exhibited high TS, SG, and pathogen content. This observation indicates that FS vacuum pumping may be difficult in the sludge zone after 3 years of excreta degradation, which may encourage the manual scavenging practice. Additionally, the analysis of FS treatment plant (FSTP) process control parameters (settled sludge volume, sludge volume index, and sludge drying capacity) indicated that the treatment time required for older FS is long, which increases the FSTP cost. Furthermore, FS intra-variation in OST exhibited that effluent FS could be directly sent for effluent treatment without any solid–liquid separation process. Thus, the present study can help practitioners in establishing or modifying FS treatment systems for addressing conditions based on the variation in FS characteristics at the town level in India.