Faculty Publications
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Item An approach to quantify the contamination potential of hazardous waste landfill leachate using the leachate pollution index(Institute for Ionics, 2024) Ambujan, A.; Thalla, A.K.A significant portion of the hazardous wastes generated by rapid industrialisation and urbanisation end up in landfills. The wastes disposed of in hazardous waste landfills are less biodegradable; thus, the leachate generated due to the physical and chemical changes in the landfill renders high toxicity. If not monitored and handled appropriately, this leachate could lead to contamination affecting human and livestock health and adversely affect the soil and agriculture in the vicinity of the landfill site. A tool to quantify the contamination caused by improper handling of hazardous waste landfill leachate is essential to understand which landfill site would need immediate attention. In the present study, the leachate pollution index is developed based on the predominantly available pollutants in hazardous waste landfill leachate and their toxicity limits. Fuzzy Delphi-Analytic Hierarchy Process has been used to develop the index. These techniques have been used for screening and assigning weights to the pollutants. Further, sub-index curves have been developed considering the available concentration, the toxicity, and the standard concentration limits for each pollutant. The weighted linear sum function has been used to aggregate the weights and sub-index scores. The hazardous waste landfill leachate pollution index developed in this study can serve as a potential tool for quantifying the leachate contamination potential. Furthermore, it can be used as a comparison tool for ranking landfill sites based on the contamination potential. © 2023, The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University.Item Screening, identification, and characterisation of bacteria in landfill leachate for polypropylene microplastic biodegradation(Taylor and Francis Ltd., 2025) Dubey, A.P.; Thalla, A.K.Plastic contamination is a serious concern for the environment, especially when it comes to microplastics. The biodegradation capability of bacterial strains isolated from landfill leachate against polypropylene microplastics (PPMPs) is examined in this study. A bacterial strain identified as Staphylococcus hominis with 99.77% sequence identity via 16S rRNA gene sequencing showed promising degrading capabilities. Over a 30-day incubation period at 37°C and 150 rpm, S. hominis reduced the weight of PPMPs from 995.2 mg to 833.5 ± 13.85 mg, suggesting a 16.25% degradation. Detailed examinations using bacterial growth tests, Field emission scanning electron microscope (FESEM), and energy-dispersive X-ray spectroscopy (EDS) show significant surface and chemical alterations in the PPMPs, confirming the degradation capability of the bacteria. The bacteria utilised carbon as an energy source, as indicated by the decrease in the percentage weight of molecular carbon from 98% to 78.5%. These findings promote the development of sustainable biological approaches to tackling plastics pollution and show the potential role of bacteria found in landfills, such as S. hominis, in the sustainable bioremediation of microplastic contamination. © 2025 Indian Institute of Chemical Engineers.Item Bioprospecting indigenous bacteria from landfill leachate for enhanced polypropylene microplastics degradation(Elsevier B.V., 2025) Dubey, A.P.; Thalla, A.K.Plastic pollution, especially microplastics (MPs), is a severe environmental threat. Due to the significant environmental issues posed by plastics, it is critical to use an effective and sustainable degradation technique. The study aimed to isolate and identify Indigenous bacterial strains from landfill leachate (LL) to evaluate its potential for degrading Polypropylene microplastics (PPMPs). The investigation identified two bacterial strains, Pseudomonas aeruginosa, and novel Staphylococcus haemolyticus, through 16S rRNA analysis, capable of decomposing PPMPs. Following a 30-day treatment period, it was noted that Staphylococcus haemolyticus reduced the dry weight of PPMPs by 25.46 % ± 1.35 %, whereas Pseudomonas aeruginosa strain reduced it by 7.01 % ± 0.85 %. Multiple tests, including weight loss, pH, optical density, total biomass yield, and BATH test of the medium, validated the growth of bacterial strains. The biochemical characteristics of the isolated strains were assessed through Biochemical tests. The study also investigated the surface, chemical, and structural changes in treated PPMPs using Scanning electron microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), and Ion Chromatography (IC) tests. The Fourier Transform Infrared Spectroscopy (FTIR) study also showed the creation of alcohol, methyl, as well as carbonyl groups due to hydrolysis and oxidation by both bacterial strains. This study implies that the Staphylococcus haemolyticus and Pseudomonas aeruginosa bacterial strains are secure and efficient for PPMP bioremediation. © 2025 Elsevier B.V.Item A comprehensive study on quantification and characterization of microplastics in compost, landfill-soil and leachate(SAGE Publications Ltd, 2025) Dubey, A.P.; Thalla, A.K.Microplastics (MPs), a category of synthetic emerging pollutants, have been detected in various environmental matrices. This study assesses the abundance of MPs in the soil, wet compost (WC), Black soldier compost (BSC) and landfill leachate (LL) of the municipal solid waste management plant. Samples were pretreated with a Fenton reagent, followed by density separation and analysed using a digital portable microscope. They were then categorized based on their shape, colour and size to provide information on their distribution. The work reveals an average MP count of 7590?±?1004.092 MP kg?1in soil. MPs were 5900?±?565.69 MP kg?1for BSC, 11,350?±?353.55 MP kg?1for WC and LL samples 98.83?±?6.83 MP L?1. Notably, a significant proportion of MPs, 85% in soil, 86% in compost and 72.6% in LL, measured size less than 300?µm. Samples showed different proportions of fragments, microbeads and fibres, with white/transparent and black being the predominant colours of MPs. Additionally, the study identifies the physicochemical properties of the samples, and the polymer types are identified using attenuated total reflectance-Fourier transform infrared spectroscopy. The study revealed that polypropylene and polyethylene are the most abundant polymers in the samples, indicating that landfills serve as significant sources of MPs. The adopted MP extraction method was tested for its recovery efficiency, and the recovery rates for leachate, compost and soil were found to be 94.3%, 80% and 77.9%, respectively. This research offers insight into the types and abundance of MPs in southern India’s landfills, prompting further studies on detection methods. © The Author(s) 2025