Circular economy approach for sustainable solid waste management: A developing economy perspective.

The notion of circular economy (CE) strengthens the approach to sustainable development (SD). It is perceived that the adoption of CE can unlock half a trillion dollars of economic value in India by the year 2030. However, embracing the CE concept can be considered a panacea to the existing issues associated with solid waste management (SWM). The proposed study explores current waste management practices and assesses the inadequacy to infer the CE as a solution for successful waste management practices. The work provides an overview of SWM in India and emphasizes the inclusion of CE in the Indian SWM sector. The comprehensive review depicts existing, and emerging waste management approaches to form a CE by processing the waste efficiently and fuelling an SD movement. The cradle-to-cradle approach in CE, national solid waste compliances/legislation, key initiatives taken by the Governments, and the influence of industry and legal framework on CE were also discussed. The work will facilitate policy and decision-makers to include CE in the Indian SWM sector.

Life-cycle assessment approach for municipal solid waste management system of Delhi city.

The life-cycle assessment (LCA) approach with route optimization technique was adopted in the present study to evaluate environmental and economic aspects associated with the prevalent waste management system in Delhi city. With an objective of cost minimization and abating environmental hazards from waste transportation systems, ArcGIS was used to identify the most appropriate route for waste transportation. The study was conducted considering four landfills located at Bawana, Bhalswa, Ghazipur and Okhla present in Delhi city. Landfilling, composting, anaerobic digestion, and recycling methods were analyzed for global warming potential (GWP), eutrophication potential (EP), acidification potential, abiotic resource depletion potential and photochemical oxidation potential parameters using LCA software GaBiPro. The results from the LCA studies for the municipal solid waste management system of Delhi city revealed that transportation emissions and landfilling negatively impact the environment. The effect of recycling rate on the landfilling, composting, anaerobic digestion was also studied using sensitivity analysis. Results of sensitivity analysis depicted that recycling of waste is inversely related to the impact categories. Overall, the results exhibited a detrimental effect of landfilling on the environment in terms of GWP and EP. Further, considering the geospatial analysis, two waste recycling stations are proposed in the vicinity of existing waste management plants to reduce the time and cost of waste transport from the landfills to the waste management plants.

Assessment of polybrominated diphenyl ether contamination and associated human exposure risk at municipal waste dumping sites.

The reports concerning the occurrence and fate of polybrominated diphenyl ethers (PBDEs) at municipal solid waste (MSW) dumping sites are scarce, and considering the Indian context, no study has been conducted to assess PBDE contamination at MSW dumping sites and associated exposure and health risk. Therefore, in the present study, the concentration of PBDE congeners was investigated in soil samples amassed from MSW dumping sites of India and the factors affecting the dissemination of different PBDE congeners in soil were evaluated. Also, the human exposure and health risk through soil intake and dermal contact were also evaluated the first time in India. The total PBDE concentrations from tri- to deBDE congeners in soil ranged from 6.81 to 33.67 µg/g dw and showed a trend towards higher levels of PBDEs in the dumping sites of more populous cities. BDE 183 was found to be the main congener in the soil of the dumping sites. The congener profile in the soil exhibited the composition of the octa- and deBDE technical mixture and possibilities of biological and photodegradation of deBDE into lower brominated congeners. A significant correlation was observed between the measures of BDE 183 and BDE 209 congeners and carbon, nitrogen and hydrogen contents of the soil. The measured exposure doses of PBDEs through soil intake and dermal contact and the hazard index was estimated higher in children as compared to adults, which indicates the increased risk and susceptibility of infants and children to PBDE exposure. The results of the present study revealed that the MSW dumping sites in India are a sink of PBDEs and might have detrimental effects on human health.

Enhanced nodulation and higher germination using sludge ash as a carrier for biofertilizer production.

Sludge ash, a byproduct resulting from the combustion of the dewatered sludge generated in the sewage treatment plants, is recognized as a hazardous solid waste throughout the world. This solid waste, which is produced in behemoth volume, has very limited applications and is directly disposed to landfills. The present study aims to explore a novel strategy for utilizing this solid waste for the development of Rhizobium biofertilizer and thus reducing the burden on landfills. The Rhizobium inoculum was prepared and mixed with sludge ash to formulate Rhizobium biofertilizer, and shelf life of this formulation was evaluated by counting colony forming unit. The prepared formulation was applied on lentil seeds, and its effect was analyzed by assessing the plant growth along with other yield characteristics. Enhanced colony forming unit count (6487.78) was observed in sludge ash carrier combination with a better shelf life of five months in comparison to lignite carrier formulation from the beginning of the experiment (9.1%) till 150th day (69.8%). Lentil seeds treated with sludge ash based biofertilizer showed luxuriant growth with 19% enhanced root length, 42% in number of nodules, 10% in plant growth and 53.40% in seed yield as compared to conventional lignite formulations. Hence, biofertilizer produced from waste material sludge ash is not supposed to cause a hazard for the soil and plants when incorporated in defined amount and can prove to be a substitute for conventional lignite carrier in biofertilizer production.

Rapid composting techniques in Indian context and utilization of black soldier fly for enhanced decomposition of biodegradable wastes - A comprehensive review.

In the present scenario, solid waste management (SWM) has become one of the main concerns for urban waste managers in the developing world. This article reviews the recent trends and technologies associated with the process of composting. Utilization of black soldier fly (BSF) larvae can be one of the rapid methods for treatment of biodegradable wastes. A detailed review of the literature indicated that more importance is to be given on the pre-processing of Municipal Solid Waste (MSW) which includes segregation of biodegradables, inerts, metals for preparing the requisite substrate for application of the suitable technology. In developing countries, major emphasis should be given on curtailing the environmental and health impacts caused due to improper management of MSW and for developing some innovative as well as economically feasible systems for proper handling of MSW. BSF can transform the biodegradable wastes into biofuels and byproducts at a minimal cost. The utilization of BSF for treating various organic waste (OW) has been thoroughly studied and discussed in detail. The salient observations on the factors affecting the growth of BSF larvae as well as comprehensive analysis of patents on breeding and utilization of BSF are also presented in this paper. The present review also assesses the potential of various rapid composting techniques and advocates about the planning and development of real-scale treatment systems by the researchers, environmental planners and policy makers to eradicate the problem of solid wastes.

Polybrominated diphenyl ethers (PBDEs) in Indian wastewater treatment plant: Occurrence, mass flow and removal.

Polybrominated diphenyl ethers (PBDEs) are categorized as a group of brominated flame retardants that cause hazardous health impacts but are still being used consistently worldwide. The studies on their occurrence and fate in wastewater treatment plants are scarce, and considering the Indian scenario, no study has been reported till date in this context. Therefore, in the present study, PBDE congeners of primary concern were investigated first time to assess the existence, dissemination and fate of PBDEs in the municipal wastewater treatment plant (MWTP) located in Nagpur city, Maharashtra, India. BDE 209 and 47 were detected as the predominant PBDE contaminants in all the analysed samples. The concentration of PBDEs was primarily found in the particulate phase of wastewater. According to mass loading analysis, 1297 mg/day concentration of PBDEs is disposed of at landfill sites in the form of sludge, while 77.46 mg/day is released via final effluent. The present investigation is the first of its kind of study conducted to evaluate the PBDE contamination in Indian MWTP, which reveals the presence of high PBDE concentration in Indian municipal sewage. The findings of the current study exhibit the need for appropriate action toward the sound surveillance of PBDEs in the Indian context.

Co-digestion of municipal solid waste with lignocellulosic waste in mesophilic Environment.

The present study deals with the dual problem of municipal solid waste and lignocellulosic waste in which authors tried to use these two waste materials as clean and renewable energy source. In the present study, anaerobic digestion of organic fraction of municipal solid waste and lignocellulosic waste in varying combinations was carried out. Five-set of experiments (S1, S2, S3, S4, and S5) under mesophilic conditions were conducted in batch reactors. From all the combinations, reactor S3 (organic fraction of municipal solid waste: lignocellulosic waste, 1:1 ratio) was observed to be the best combination producing 70.09 ml concentration of methane out of 78.76 ml of biogas as compared to all other combinations. The increase in methane production rate was observed by 53.67% due to the addition of lignocellulosic waste. The decline in methane production at the end of the 50th day was observed due to a fall in pH, which created acidic conditions, thus inhibiting the conversion process. It was found that the mesophilic condition acted as a governing factor in the process of digestion.

Antibiotic resistance in the environment: a critical insight on its occurrence, fate, and eco-toxicity.

The overuse, misuse, and underuse of antibiotics tend to increase the antibiotic burden in the environment resulting into the evolution in microbial community to possess resistance that renders antibiotics ineffective against them. The current review recapitulates the present state of knowledge about the occurrence and fate of antibiotics in various environmental matrices. Also, the prevalence of antibiotic-resistant bacteria/antibiotic-resistant genes (ARB/ARGs) in various biological and non-biological systems, eco-toxicity of antibiotics on non-target organisms, and remediation methods for antibiotics and ARB/ARGs removal were critically reviewed. Furthermore, a comparison of various technologies for their efficiency to eliminate antibiotic residues and ARB/ARGs is made. The study identified gaps in the investigation of toxic effects of low concentration of antibiotics and the mixture of multiple antibiotics on non-target organisms. The study of antibiotics' phytotoxicity and toxicity towards sediment and soil-dwelling organisms are also recognized as a knowledge gap. The review also details policies implemented across the globe to fight against antibiotic resistance, and the scarcity of data on lab to land transferred remediation technology was identified. The present study entails a critical review of literature providing guidelines for the articulation of policies for prudent use of antibiotics, limits on the amount of antibiotics in pharmaceutical formulations, and regular surveillance in the Indian context.

Aerobic degradation of decabrominated diphenyl ether through a novel bacterium isolated from municipal waste dumping site: Identification, degradation and metabolic pathway.

In the present study, a novel bacterium capable of degrading BDE-209 aerobically was isolated from a municipal waste dumping site and identified as Bacillus tequilensis strain BDE-S1 through 16S rRNA gene sequencing. A correlation between BDE-209 and bromide concentration, COD, TOC, and cell biomass was established. 65% of 50 mg/L initial concentration of BDE-209 was degraded within eight days of incubation by BDE-S1 strain. Two hexa, two penta, one tetra-BDE congener, and benzamide were detected as metabolites. The bromide release, COD, TOC and cell biomass were found to be significantly correlated parameters with BDE-209 degradation. Based on the metabolite analysis, ortho and meta debromination, cleavage of diphenyl ether bond and ring-opening were suggested as possible degradation pathways. This is the first study demonstrating the use of indigenously isolated Bacillus tequilensis strain BDE-S1 for aerobic degradation of BDE-209, which could provide new comprehension for bioremediation of PBDEs from contaminated environments.

Polybrominated diphenyl ethers in the environment: a wake-up call for concerted action in India.

Polybrominated diphenyl ethers (PBDEs) are a class of persistent organic pollutants (POPs) used as flame retardants in the products utilized in day-to-day life. Their bioaccumulation, low volatility, and high persistence in the environment have led to their global spread even to remote and distant regions. The present study identifies gaps in the investigation of the neurotoxic potential of PBDEs, their effects on brain development, toxicokinetic, and their potential as a carcinogen. In India, to date, only human breast milk was assessed for levels of PBDEs, and it is suggested that other human tissues can also be explored. No data on the reproductive toxicity of PBDEs are reported from Indian cohorts. Long-range transport and deposition of PBDEs in colder regions necessitates monitoring of Himalayan regions in India. An inventory of PBDEs is required to be made for addressing the worrisome situation of the unregulated import of E-waste from the developed countries in India. The study also emphasizes providing guidelines for the articulation of policies regarding sound surveillance and management of PBDE production, consumption, and release in the Indian context. It is recommended that a separate cell for monitoring and follow-up of PBDEs should be established in India. Also, the development of better alternatives and environment-friendly remediation technologies for PBDEs is the need of the hour.

Rapid-in-house composting of organic solid wastes with fly ash supplementation: Performance evaluation at thermophilic exposures.

The present work was envisaged to design, fabricate, and evaluate the performance of rapid in-house composters (RICs) for composting of organic wastes comprising kitchen waste and brown waste with fly ash supplementation in the fixed combination. The prime objective of the present study was to evaluate the ideal operating temperature suitable for rapid action of pro-composting microorganisms in indigenously developed RIC. Four identical RICs were exposed to temperatures of 40 â„ƒ, 45  â„ƒ, 55 â„ƒ, and 65 â„ƒ, respectively. The factors governing the composting process were regulated through specifically designed components. Qualitative parameters like pH, moisture content (MC), C/N ratio and heavy metals were analyzed at regular intervals. Principal component analysis was used to evaluate the relationship between the obtained results. The RIC with 55 â„ƒ temperature exposure, 70% MC for nine days and aeration at 4 L per minute exhibited the best results with 15.13C/N ratios of compost.

Exploring the synergic effect of fly ash and garbage enzymes on biotransformation of organic wastes in in-vessel composting system.

The aim of the present work was to study the synergic effect of fly ash (FA) and garbage enzymes (GE) on biotransformation of organic wastes in in-vessel composting system. In-vessel composting of organic waste (household + brown in vessel 1) was performed with fly ash (mixed 5% in vessel 2; 10% in vessel 3; 15% in vessel 4; and 20% in vessel 5) by addition of extra carbon source (5%) and garbage enzyme in a fixed-dose (5%) for 15 days and changes in chemical properties (C: N ratio, nitrates, sulphates, phosphates and macro-elements) were analyzed at maturity. Vessel 5 showed better results in terms of organic matter degradability and C: N ratio (13.68) of mature compost. Principal Component Analysis (PCS) also confirmed vessel 5 as the best performing among other vessels. FTIR analysis indicated a major shift in chemical structure of organic waste due to the composting action.

Fly ash as an additive for enhancing microbial and enzymatic activities in in-vessel composting of organic wastes.

In the present study, fly ash was used as an additive for the rapid composting of biomass and kitchen waste with jaggery as an activator. The in-vessel composting experiments were carried out in ten plastic vessels of 15 L capacity containing varying amounts of fly ash, biomass waste, and kitchen waste. The effect of fly ash on the microbial and enzymatic activity of the composting system was also ascertained. The compost in Vessel No. 10 having a combination of 50% biomass waste, 30% kitchen waste, and 20% fly ash seemed to have a significant effect on the compost quality. Statistical analysis revealed Vessel No. 10 as significantly separated from other vessels whereas microbial activity (342.67 CFU 108/g), pH (8.15), temperature (48.50 °C), and heavy metals, such as Ni (0.1239 mg kg-1), Ba (0.6109 mg kg-1), Cd (0.0004 mg kg-1) were the most influential variables for the separation.

Synergistic effect of fly ash in in-vessel composting of biomass and kitchen waste.

The present study aims to utilize coal fly ash for its property to adsorb heavy metals and thus reducing the bioavailability of the metals for plant uptake. Fly ash was incorporated into the in-vessel composting system along with organic waste. The in-vessel composting experiments were conducted in ten plastic vessels of 15 L capacity comprising varying proportions of biomass waste, kitchen waste and fly ash. In this study, maximum degradation of organic matter was observed in Vessel 3 having k value of 0.550 d-1. In vessel 10, 20% fly ash with a combination of 50% biomass waste and 30% kitchen waste along with the addition of 5% jaggery as an additive produced the best outcome with least organic matter (%C) loss and lowest value of rate constant (k).