Faculty Publications
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Item Biocatalytic Remediation of Industrial Pollutants(Springer Science and Business Media Deutschland GmbH, 2023) Pallavi, P.; Manikandan, S.K.; Nair, V.The release of an significant amount of pollutants from various industrial activities pose a serious threat to environmental sustainability and ecological integrity. Toxic pollutants, such as dyes, pesticides, metal ions, plastics, and antibiotics, can cause detrimental diseases to diverse living beings in their ecosystems. Biocatalytic remediation is one efficient method of removing toxic industrial pollutants by applying microorganisms or enzymes. Microorganisms in the environment typically produce a variety of enzymes to immobilize and degrade contaminants by using them as a substrate for growth and development. Biocatalytic remediation has attracted enormous interest worldwide due to its affordability and eco-friendliness. The use of microbial enzymes and microorganisms, especially immobilized biocatalysts, has been established as a flexible approach for the sustainable alleviation of industrial pollutants, in contrast to physical and chemical methods. This chapter presents and discusses recent scientific and technological advancements related to biocatalytic remediation of industrial pollutants. It also considers different biocatalysts and novel methodologies to mitigate various pollutants. This article also examines current trends, challenges, and directions for efficiently removing pollutant using biocatalysis method. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.Item Developing a biocatalyst showcasing the synergistic effect of rice husk biochar and bacterial cells for the removal of heavy metals(Royal Society of Chemistry, 2023) Manikandan, S.K.; Nair, V.Heavy metals like cadmium (Cd) and nickel (Ni) are toxic pollutants that affect the environment and pose health risks. Removal of Cd and Ni through bioremediation in the presence of biochar is a sustainable strategy. This study investigated the removal of Cd and Ni by Pseudomonas stutzeri immobilized on rice husk biochar (PRHB). The removal efficiency was calculated by varying the culture incubation time, pH, temperature, biocatalyst dosage, and initial metal ion concentration. PRHB showed a maximum metal removal capacity of 95% Cd and 92% Ni. The removal efficiency of PRHB was higher than that of free cells, which could be attributed to simultaneous adsorption, ion exchange, complexation, precipitation, and bioaccumulation caused by the biochar carrier and bacteria. The rice husk biochar material served as both an adsorbent and a carrier supplying nutrients for the growth of the bacteria. Considering the excellent metal ion removal capability and reusability, the use of PRHB could be a promising, cost-effective, and environment-friendly strategy for treating wastewater containing heavy metals. © 2023 The Royal Society of Chemistry.Item Optimization and mechanistic study on bioremediation of Cr (VI) using microbial cell immobilized sugarcane bagasse biochar(Elsevier Ltd, 2024) Pallavi, P.; Manikandan, S.; Nair, V.Hexavalent chromium (Cr (VI)), a highly toxic heavy metal, contaminates water bodies due to its heavy usage in industrial processes. The present study proposes an environmentally friendly strategy for the bioremediation of Cr (VI) from water systems. Bacillus sp. was immobilized onto sugarcane bagasse biochar (BSCB) to remediate Cr (VI). The Cr (VI) removal process was optimized through one-factor-at-a-time (OFAT) and response surface methodology (RSM). Results showed that BSCB effectively removed 93.56 % of Cr (VI), with optimum conditions of 100 mg L−1 initial Cr (VI) concentration, 12 h incubation time, 40 °C temperature, pH 7.0, and 0.1 % BSCB dosage. The study also investigated reusability of BSCB across five consecutive cycles for the removal of Cr (VI) under optimized operating conditions, showcasing its consistent high performance compared to both sugarcane bagasse biochar (SCB) and free cells. BSCB maintained an average removal efficiency of 88.2 % across three cycles, outperforming SCB (56.67 %) and free cells (82.24 %). This immobilization approach enables better recovery of bacterial cells from water bodies and presents a sustainable, cost-effective bioremediation solution for Cr (VI) removal. © 2024 Elsevier LtdItem Mechanistic understanding of biochar-bacteria system for enhanced chlorpyrifos bioremediation in water and soil medium(Elsevier B.V., 2024) Manikandan, S.; Mariyam, A.; Gowda, N.G.; Singh, A.; Nair, V.Chlorpyrifos (CP) is a commonly used chlorinated organophosphorus insecticide in agriculture, but its improper handling and long-term application have led to the contamination of groundwater, soil, and sediments. The use of functional microorganisms immobilized on biochar is an innovative and sustainable solution to this issue. In this study, CP-degrading Aeromonas veronii (A.veronii) was immobilized on rice husk biochar (ARHB) to investigate its efficacy in remediating CP-contaminated water and soil. Box-Behnken designs were employed to optimize the parameters, resulting in 96.25 % removal within 24 h in water medium. Adding 2 g kg−1 ARHB in soil achieved a maximum removal rate of 92.4 % within 42 days. Moreover, ARHB enhanced soil properties and plant growth through bio-augmentation and bio-stimulation. LC-MS analyses identified the degradation products, signifying a synergistic effect of bacterial metabolism and adsorption in the CP removal mechanism. These findings highlight the potential of immobilized A.veronii and biochar for efficient remediation of pesticide-contaminated environments. © 2024 Elsevier B.V.Item Mechanistic studies on bioremediation of dye using Aeromonas veronii immobilized peanut shell biochar(Academic Press Inc., 2024) Singh, A.; Manikandan, S.K.; Nair, V.Recalcitrant chemicals in the environment not only present obstacles to living organisms but also contribute to the degradation of natural resources. One contribution to environmental pollution is the discharge of synthetic dyes from the textile sector. This study investigates the combined effect of microbial cells and biochar on eliminating methyl orange (MO) dye. The immobilization of Aeromonas veronii on peanut shell biochar (APSB) was conducted to investigate its efficacy in removing MO dye from water. PSB synthesized by pyrolysis at 300 °C for 120 min showed maximum bacterial immobilization potential. The highest degradation rate of 96.19 % was achieved in APSB within 96 h using MO dye concentration of 100 mg L?1, incubation temperature of 37 °C, pH 7, and biocatalyst dosage of 1g L?1. In comparison, free cells achieved degradation rates of 72.53 % and 61.56 % for PSB. Moreover, the adsorption process was primarily controlled by PSB, with subsequent dye mineralization by A. veronii, as supported by FTIR and LC-MS studies. Moreover, this innovative approach exhibited the reusability of the biocatalyst, giving 76.23 % removal after fifth cycle, suggesting sustainable alternative in dye remediation and potential option for real-time applications. © 2024 Elsevier Inc.Item Dual-role of coconut shell biochar as a soil enhancer and catalyst support in bioremediation(Springer Science and Business Media Deutschland GmbH, 2025) Manikandan, S.K.; Nair, V.The application of soil amendments has been proposed to influence soil properties, thereby improving agricultural productivity. They are known to increase the organic matter content, water holding capacity, and soil porosity, which play a significant role in the growth and development of plants. In work, experiments were carried out to evaluate the impact of coconut shell biochar as a soil amendment and microbial cell support to remediate cadmium-contaminated soil. To investigate the roles of biochar size and concentration on soil water holding capacity, the laterite loam soil is mixed with the biochar having different particle sizes of less than 1 mm, 1–2 mm, and 2–5 mm and concentrations of 1%, 5%, and 10% (w/w). The effects of combining biochar with different concentrations of 1%, 5%, and 10% (w/w) of farmyard manure on plant growth of Solanum lycopersicum L, soil nutrient changes, and enzyme activity are also investigated. The biochar particle size of <1 mm and concentration of 10% showed the highest (41.5%) water holding capacity and 90.47% germination, and 464.25 seed vigour index for Solanum lycopersicum L. Further 21 days soil incubation experiments were conducted to explain the effect of the biochar, and P. stutzeri immobilized on biochar on cadmium adsorption and bioavailability in soil. Cadmium removal of about 73.84% was obtained from contaminated soil compared to the control. It is suggested that coconut shell biochar generation from coconut shells could be a sustainable crop residue management option to enhance the soil physico chemical properties and also to remediate soil. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.