School Of Environment And Earth Sciences

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Subject: search.filters.subject.Enzyme activity

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    Influence of urban sewage sludge amendment on agricultural soil parameters
    (Elsevier B.V., 2021-05-19T00:00:00) Dhanker, Rinku; Chaudhary, Suman; Goyal, Sneh; Garg, Vinod Kumar
    Using sewage sludge for agricultural soil conditioning may be a potential alternative for its proper disposal and enhancing soil fertility by virtue of its high content of organic matter and several important plant nutrients. But the presence of toxic heavy metals and pathogens limits its use. Accordingly, the aim of this study was to assess the impact of different doses of sewage sludge (5, 10, 20, 30 and 50 t ha?1) on physico-chemical and biological properties of sandy loam soil. It was observed that different soil parameters significantly changed according to the addition of different sewage sludge doses as compared to untreated control soil. Total organic carbon (TOC) and nitrogen (N) consistently improved up to the application of 50 t ha?1 sewage sludge. Consequently, it led to a significant and rapid increase in soil microbial properties like microbial biomass, basal respiration and enzyme activities (alkaline phosphatase, dehydrogenase and urease) during the initial days of incubation, which gradually decreased up to 90 days. Sewage sludge also increased the Diethylenetriamine Pentaacetic Acid (DTPA) extractable available form of heavy metals (Ni, Cr, Pb, Cu and Cd). However, all values of available forms of heavy metals were below the threshold values for contaminated soil. � 2021 Elsevier B.V.
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    Effect of enzyme secreting bacterial pretreatment on enhancement of aerobic digestion potential of waste activated sludge interceded through EDTA
    (Elsevier Ltd, 2013) Kavitha, S.; Adish Kumar, S.; Yogalakshmi, K.N.; Kaliappan, S.; Rajesh Banu, J.
    In this study, the effect of Ethylene diamine tetra acetic acid (EDTA) on Extracellular polymeric substance (EPS) removal tailed with bacterial enzymatic pretreatment on aerobic digestion of activated sludge was studied. In order to enhance the accessibility of sludge to the enzyme secreting bacteria; the extracellular polymeric substances were removed using EDTA. EDTA efficiently removed the EPS with limited cell lysis and enhanced the sludge enzyme activity at its lower concentration of 0.2. g/g SS. The sludge was then subjected to bacterial pretreatment to enhance the aerobic digestion. In aerobic digestion the best results in terms of Suspended solids (SS) reduction (48.5%) and COD (Chemical oxygen demand) solubilization (47.3%) was obtained in experimental reactor than in control. These results imply that aerobic digestion can be enhanced efficiently through bacterial pretreatment of EPS removed sludge. ? 2013 Elsevier Ltd.
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    Laccase immobilized magnetic iron nanoparticles: Fabrication and its performance evaluation in chlorpyrifos degradation
    (Elsevier Ltd, 2017) Das, A.; Singh, J.; Yogalakshmi, K.N.
    Chlorpyrifos degradation was studied using laccase immobilized on magnetic iron nanoparticles (CENPs). The magnetic iron nanoparticles (MNPs) prepared by co-precipitation method were characterized using Transmission electron microscopy (TEM), Scanning electron microscopy- Energy dispersive spectroscopy (SEM-EDS) and Thermogravimetric analysis (TGA). The size of the nanoparticles ranged between 10 and 15 nm. The MNPs were coated with chitosan, surface modified with carbodiimide (EDAC) immobilized with laccase enzymes. The chlorpyrifos degradation studies were performed in batch studies under constant shaking for a period of 12 h. Results of the study showed that laccase immobilized on magnetic iron nanoparticles were effective in degrading more than 99% chlorpyrifos in 12 h at pH 7 and 60 ?C. In the overall degradation percentage, MNPs contributed to 32.3% of chlorpyrifos removal while ENPs resulted in 58.8% chlorpyrifos degradation. Immobilization of enzyme decreased the overall activity of the free enzyme. The CENPs showed 95% activity after five repeated washing and hence possess good reusability potential. ? 2017 Elsevier Ltd