Faculty Publications
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Item Artificial neural network based modeling to evaluate methane yield from biogas in a laboratory-scale anaerobic bioreactor(Elsevier Ltd, 2016) Nair, V.V.; Dhar, H.; Kumar, S.; Thalla, A.K.; Mukherjee, S.; Wong, J.W.C.The performance of a laboratory-scale anaerobic bioreactor was investigated in the present study to determine methane (CH4) content in biogas yield from digestion of organic fraction of municipal solid waste (OFMSW). OFMSW consists of food waste, vegetable waste and yard trimming. An organic loading between 40 and 120 kg VS/m3 was applied in different runs of the bioreactor. The study was aimed to focus on the effects of various factors, such as pH, moisture content (MC), total volatile solids (TVS), volatile fatty acids (VFAs), and CH4 fraction on biogas production. OFMSW witnessed high CH4 yield as 346.65 L CH4/kg VS added. A target of 60–70% of CH4 fraction in biogas was set as an optimized condition. The experimental results were statistically optimized by application of ANN model using free forward back propagation in MATLAB environment. © 2016 Elsevier LtdItem The combined effects of carbon/nitrogen ratio, suspended biomass, hydraulic retention time and dissolved oxygen on nutrient removal in a laboratory-scale anaerobic–anoxic–oxic activated sludge biofilm reactor(IWA Publishing, 2018) Manu, D.S.; Thalla, A.K.The current trend in sustainable development deals mainly with environmental management. There is a need for economically affordable, advanced treatment methods for the proper treatment and management of domestic wastewater containing excess nutrients (such as nitrogen and phosphorus) which can cause eutrophication. The reduction of the excess nutrient content of wastewater by appropriate technology is of much concern to the environmentalist. In the current study, a novel integrated anaerobic–anoxic–oxic activated sludge biofilm (A2O-AS-biofilm) reactor was designed and operated to improve the biological nutrient removal by varying reactor operating conditions such as carbon to nitrogen (C/N) ratio, suspended biomass, hydraulic retention time (HRT) and dissolved oxygen (DO). Based on various trials, it was seen that the A2O-AS-biofilm reactor achieved good removal efficiencies with regard to chemical oxygen demand (95.5%), total phosphorus (93.1%), ammonia nitrogen concentration (NH4þ-N) (98%) and total nitrogen (80%) when the reactor was maintained at C/N ratio of 4, suspended biomass of 3 to 3.5 g/L, HRT of 10 h, and DO of 1.5 to 2.5 mg/L. Scanning electron microscopy (SEM) of suspended and attached biofilm showed a dense structure of coccus and bacillus bacteria with the diameter ranging from 0.3 to 1.2 ?m. The Fourier transform infrared (FTIR) spectroscopy results indicated phosphorylated macromolecules and carbohydrates mix or bind with extracellular proteins in exopolysaccharides. © IWA Publishing 2018.Item Life cycle assessment of municipal solid waste management options for India(Elsevier Ltd, 2019) Khandelwal, H.; Thalla, A.K.; Kumar, S.; Kumar, R.Life Cycle Assessment (LCA) tool can be used for environmental assessment of Municipal Solid Waste Management (MSWM) system. The present study aims to evaluate the impact of MSWM system in Nagpur city, India under four different scenarios. i.e., composting combined with landfilling (S1), material recovery facility (MRF) & composting combined with landfilling (S2), MRF & anaerobic digestion (AD) combined with landfilling (S3) and MRF, AD & composting combined with landfilling (S4) using LCA tool. The sensitivity analysis was also performed for evaluating the influence of recycling rate of valuable resources in all the considered scenarios. The scenarios were compared using Gabi 8.5.0.79 model and CML-1A impact characterization method. S2 was found to have the least environmental impacts on global warming, human toxicity, eutrophication, and photochemical ozone creation potential categories. The sensitivity analysis indicated an inversely proportional relation between change in recycling rate and total environmental burdens. © 2019 Elsevier LtdItem Occurrence and environmental risks of nonsteroidal anti-inflammatory drugs in urban wastewater in the southwest monsoon region of India(Springer, 2020) Thalla, A.K.; Vannarath, A.S.Municipal wastewater treatment plants (MWWTPs) are considered to reduce the amount of pollutants that enter water reservoirs as a result of wastewater disposal. An assessment of the occurrence and removal of pharmaceutical compounds, mainly nonsteroidal anti-inflammatory drugs (NSAIDs), in wastewater from the Kavoor MWWTP (southwest monsoon region), India, is presented in this paper. The performance of the MWWTP was monitored in the summer (May) and monsoon (September) periods. The highest inlet concentrations of diclofenac, naproxen, ibuprofen, ketoprofen, and acetylsalicylic acid in the wastewater were observed in May and were 721.37, 2132.48, 2109.875, 2747.29, and 2213.36 ?g/L, respectively. The ketoprofen content was found to be higher than that of other NSAIDs in the influent in both seasons, whereas the diclofenac content was found to be the lowest. The removal efficiency (RE) of the target NSAIDs in the Kavoor secondary treatment plant varied from 81.82–98.92% during the summer season. During the monsoon season, the influent NSAID concentration level dropped, probably because of infiltration in old sewer pipes. In addition, a 100% RE was achieved for all the target NSAIDs in the wastewater of the MWWTP. The results showed that secondary treatment plants have the potential to remove NSAID compounds from municipal sewage with consistent performance. The environmental hazards caused by the accumulation of such compounds in water reservoirs are due to open discharge. The environmental risk levels of these compounds were also studied by the environmental risk assessment (ERA) using the European Agency for Evaluation of Medicines approach. © 2020, Springer Nature Switzerland AG.Item Polymer-based immobilized Fe2O3–TiO2/PVP catalyst preparation method and the degradation of triclosan in treated greywater effluent by solar photocatalysis(Academic Press, 2021) Pragada, S.C.; Thalla, A.K.The present study involves a novel protocol to develop a ternary composite catalyst for an effective post-treatment technique for greywater. The ternary film of Fe2O3–TiO2/polyvinyl pyrrolidine (PVP) is coated on a glass tube using spray coating with annealing at 320 °C. The structure, thermal, microstructure, and surface properties of the coated film are characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and Thermo Gravimetric Analysis (TGA). The scratch hardness of photocatalysts at different Fe2O3/TiO2 compositions is investigated based on the width measurement of scratch using FESEM analysis. Results show that at an optimum coating of 5% of Fe2O3/TiO2 composition catalytic film, the maximum scratch hardness (7.984 GPa) is obtained. Also, the photocatalyst has the highest cohesive bond strength and wearing resistance. The degradation of triclosan (TCS) in treated greywater, discharged from the anaerobic-aerobic treatment system, is investigated at a lab-scale using a solar photocatalytic reactor. The response surface analysis has been performed from the different sets of experimental trials for various optimal parameters. It is observed that the TCS degradation efficiency of 83.27% has resulted under optimum conditions. © 2021 Elsevier LtdItem Effects of chemical pretreatments on material solubilization of Areca catechu L. husk: Digestion, biodegradability, and kinetic studies for biogas yield(Academic Press, 2022) Vannarath, A.; Thalla, A.K.This study aimed to understand the pretreatment-aided anaerobic digestion of lignocellulosic residues and to assess the substrate solubilization capacity of pretreatment processes. We evaluated the feasibility of biogas production using chemically pretreated Areca catechu L. (Arecanut husk, AH). AH was pretreated for 24h at two different temperatures—25 °C and 90 °C with four different chemicals viz. H2SO4 (acidic), NaOH (alkaline), H2O2 (oxidative), and ethanol in 1% H2SO4 (organosolv) under each temperature. AH solubilization assessment included analyses of parameters such as volatile solids to total solids (VS:TS) ratio, soluble chemical oxygen demand, total phenolic content, and biomass composition. Alkaline pretreatment of AH at 90 °C resulted in the maximum biogas yield of 683.89mL/gVS, which was 2.3 times more than that obtained using raw AH without pretreatment. Methane content of biogas produced using AH pretreated with 2–10% of NaOH was found to be between 71.53% and 75.06%; methane content of biogas using raw AH was 62.31%. In order to describe the AH degradation patterns, biogas production potential from pretreated AH was evaluated using bacterial kinetic growth models (First-order exponential, logistic, transference, and modified Gompertz models). The modified Gompertz and logistic models (correlation coefficient >0.99) were found to have the best fit of all kinetic models for the cumulative experimental biogas curve. We formulated a multiple linear regression equation depicting the biodegradability index (BI) as a technical tool to determine biomethane production; BI is represented as a function of biomass composition (cellulose, hemicellulose, and lignin), with a high correlation (>0.95). Based on our analyses of AH pretreatment and substrate utilization for biogas production, we propose that the biochemical composition of lignocellulosic residues should be carefully considered to ensure their biodegradability when subjected to anaerobic digestion. © 2022 Elsevier LtdItem Extraction of iron from laterite soil and green synthesis of laterite nano iron catalyst (GLaNICs) for its application as Fenton's catalyst in the degradation of triclosan(IWA Publishing, 2022) Rashmishree, K.N.; Bhaskar, S.; Shrihari, S.; Thalla, A.K.Laterite based nano iron particles were synthesized using natural laterite extract as a precursor and Psidium guajava plant extract for its application as Fenton's catalyst in the degradation of triclosan. Chemical digestion method was used for the extraction of iron from laterite soil. Synthesized nano iron catalyst was characterized using SEM-EDS, XRD and FTIR and evaluated for its catalytic application in the Fenton's oxidation of triclosan. Maximum triclosan degradation of 69.5% was observed with nano iron catalyst dosage of 0.1 g/L and hydrogen peroxide dosage of 200 mg/L at acidic pH of 3. Hydrogen peroxide influence on the process was observed with Fenton's oxidation. Role of iron in the process has been accessed by control experiment with no nano catalyst addition in which degradation is considerably low. Fenton's oxidation was compared with conventional Fenton's oxidation driven by a green nano iron catalyst. Study claims the usage of natural laterite iron as a replacement for commercial iron in Fenton's degradation of triclosan. Regeneration and reusability studies on catalyst were studied and synthesized catalyst was observed to be reusable in three consecutive cycles. Degradation of triclosan in Fenton's oxidation follows pseudo-second order reaction with linear fit. © 2022 The Authors.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