Faculty Publications
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Item Aerobic sludge granulation and enhanced dicamba removal efficiency in the presence of AQS redox mediator in a lab-scale anaerobic-aerobic treatment method(Elsevier, 2021) Basappa, M.G.; Manu, B.The biodegrading of dicamba was conducted using the anaerobic-aerobic technique for influent concentrations 60-100 mg/L over 187 days of operation. The reactors were stabilized using starch and acclimated to 40 mg/L of dicamba. Dicamba and starch was fed to the anaerobic reactor. Effluent was collected after a hydraulic retention time of 24 h and analyzed in gas chromatography-high-resolution mass spectrometry to detect the biotransformation products. High concentration of benzoates, esters, and fatty acid groups were detected in the anaerobic reactor. Effluent of anaerobic reactor contained high chemical oxygen demand (COD) concentration 400-750 mg/L, which was then fed to the aerobic reactor. After aerobic posttreatment, the overall dicamba and COD removal obtained were >85 and 92% respectively. The aerobic reactor developed a thick granular biomass of up to 7 mm in size, which indicates the bacterial adaptation and hence attainment of stable reactor performance. © 2021 Elsevier B.V. All rights reserved.Item Anaerobic co-digestion of 2,4-dichlorophenoxyacetic acid with starch followed by aerobic post-treatment and identification of dominant bacteria(Springer Science and Business Media Deutschland GmbH, 2021) Mahesh, G.B.; Manu, B.This study was conducted to investigate the new method comprising of sequential anaerobic followed by aerobic batch reactor treatment for 2,4-dichlorophenoxyacetic acid (2,4-D). The various parameters influencing on the anaerobic digestion like pH, temperature, oxidation reduction potential (ORP) have been monitored during the 60 days study period. pH range of 6.5–7.2, temperature greater than 31.4 °C and ORP values between −250 and −300 mV have reported better reactor performance with high 2,4-D removal and biogas production. The complete biotransformation of 2,4-D in the anaerobic reactor is indicated by disappearance of intensity peak in the high-performance liquid chromatograph (HPLC) report, high biogas production of 12–18% than control and COD removal efficiency of 99%. Dominant bacterial community in the sludge was identified using SEM images. The results of this study indicate that anaerobic reactor and aerobic post-treatment method can make the treatment highly efficient. © Springer Nature Singapore Pte Ltd 2021.Item Inhibitory and stimulating effect of single and multi-metal ions on hexavalent chromium reduction by Acinetobacter sp. Cr-B2(Kluwer Academic Publishers, 2014) Hora, A.; Shetty K, V.Potential application of chromium reducing bacteria for industrial scale wastewater treatment demands that effect of presence of other metal ions on rate of Cr(VI) reduction be investigated, as industrial wastewaters contain many toxic metal ions. In the current study, the effect of different heavy metal ions (nickel, zinc, cadmium, copper, lead, iron) on chromium reduction by a novel strain of Acinetobacter sp. Cr-B2 that shows high tolerance up to 1,100 mg/L and high Cr(VI) reducing capacity was investigated. The alteration in Cr(VI) reduction capacity of Cr-B2 was studied both in presence of individual metal ions and in the presence of multi-metal ions at different concentrations. The study showed that the Cr(VI) reduction rates decreased in presence of Ni2+, Zn2+ and Cd2+ when present individually. Pb2+ at lower concentration did not show significant effect while Cu2+ and Fe3+ stimulated the rate of Cr(VI) reduction. In the studies on multi-metal ions, it was observed that in presence of Cu2+ and Fe3+, the inhibiting effect of Ni2+, Zn2+, Cd2+ and Pb2+ on Cr(VI) reduction was reduced. Each of these metals affect the overall rate of Cr(VI) reduction by Cr-B2. This work highlights the need to consider the presence of other heavy metal ions in wastewater when assessing the bioreduction of Cr(VI) and while designing the bioreactors for the purpose, as rate of reduction is altered by their presence. © 2014, Springer Science+Business Media Dordrecht.Item Biodegradation of ametryn and dicamba in a sequential anaerobic-aerobic batch reactor: A case study(IWA Publishing 12 Caxton Street London SW1H 0QS, 2019) Mahesh, G.B.; Manu, B.Agricultural runoff often contains persistent halogenated herbicide compounds like 2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine (ametryn) and 3,6-dichloro-2-methoxybenzoic acid (dicamba). These can enter the food chain through drinking water, causing serious effects for people and the environment. A sequential anaerobic reactor followed by an aerobic reactor was operated and investigated for herbicide removal efficiency at constant, three-day, hydraulic retention time (HRT) and organic loading rate (OLR) of 0.2025 kg-COD/m3/d. The effect of the herbicides on anaerobic bacteria was evaluated based on total biogas production and bacterial activity, which indicated that there was no inhibition on the acclimated biomass. The sequential reactor pair removed 72% of ametryn and 78% dicamba, with COD removal efficiencies of 86% and 85% respectively. The different high-performance liquid chromatography (HPLC) peaks indicate that the compounds are biotransformed and this was confirmed by gas chromatograph high resolution mass spectrometry (GC-HRMS). © IWA Publishing 2019.Item Removal of ametryn and organic matter from wastewater using sequential anaerobic-aerobic batch reactor: A performance evaluation study(Academic Press, 2019) Mahesh, G.B.; Manu, B.The present study was aimed to investigate biodegradation of 2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine (ametryn) in a laboratory-scale anaerobic sequential batch reactor (ASBR) and followed by aerobic post-treatment. Co-treatment of ametryn with starch is carried out at ambient environmental conditions. The treatment process lasted up to 150 days of operation at a constant hydraulic retention time (HRT) of 24 h and an organic loading rate (OLR) of 0.21–0.215 kg-COD/m3/d. Ametryn concentration of 4 and 6 mg/L was removed completely within 48–50 days of operation with chemical oxygen demand (COD) removal efficiencies >85% at optimum reactor conditions. Ametryn acted as a nutrient/carbon source rather causing toxicity and contributed to methane gas production and sludge granulation in the anaerobic reactor. Biotransformation products of ametryn to cyanuric acid, biuret, and their further conversion to ammonia nitrogen and CO2 are monitored during the study. Adsorption of ametryn on to reactor sludge was negligible, sludge granulation, presence of ANAMMOX bacteria, and low MLVSS/MLSS ratio between 0.68 and 0.72. The study revealed that ametryn removal occurred mainly due to biodegradation and co-metabolism processes. Aerobic post-treatment of anaerobic effluent was able to remove COD up to 95%. The results of this study exhibit that anaerobic-aerobic treatment is feasible due to easy operation, economic, and highly efficient. © 2019 Elsevier LtdItem Experimental investigation for treating ibuprofen and triclosan by biosurfactant from domestic wastewater(Academic Press, 2023) Jayalatha, N.A.; Devatha, C.P.The presence of emerging pollutants of pharmaceutical products and personal care products (PPCPs) in the aquatic environment overspreads the threat on living beings. Bioremediation is a promising option for treating wastewater. In the present study, an experimental investigation was carried out to produce a biosurfactant by Pseudomonas aeruginosa (MTCC 1688) for the removal of Ibuprofen (IBU) and Triclosan (TCS) from domestic wastewater. It was performed in three stages. Firstly, the production and optimization of biosurfactant was carried out to arrive at the best combination of crude sunflower oil, sucrose and ammonium bicarbonate (10%: 5.5 g/L: 1 g/L) to yield effective biosurfactant production (crude biosurfactant) and further extended to achieve critical micelle concentration (CMC) formation by dilution (biosurfactant at 10.5%). The stability of the biosurfactant was also confirmed. Biosurfactant showed a reduction in the surface tension to 41 mN/m with a yield concentration of 11.2 g/L. Secondly, its effectiveness was evaluated for the removal of IBU and TCS from the domestic wastewater collected during the dry and rainy seasons. Complete removal of IBU was achieved at 36 h & 6 h and TCS at 6 h & 1 h by crude biosurfactant and biosurfactant at CMC formation for the dry season sample. IBU removal was achieved in 2 h by both crude and biosurfactant at CMC and no TCS was detected in the rainy season sample. Thirdly, biotransformation intermediates of IBU and TCS formed during the application of the biosurfactant and degradation pathways are proposed based on the Liquid Chromatography-Mass Spectrometry (LC-MS) and it indicates that there is no formation of toxic by-products. Based on the results, it is evident that biosurfactant at CMC has performed better for the removal of IBU and TCS than crude biosurfactants without any formation of toxic intermediates. Hence, this study proved to be an eco-friendly, cost-effective and sustainable treatment option for domestic wastewater treatment. © 2022 Elsevier Ltd