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Subject: search.filters.subject.Anaerobic-aerobic treatment

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    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.
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    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 Ltd
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    Use of redox mediators for the enhanced degradation of selected nitrophenols
    (Springer Verlag, 2019) Yaseen, M.; Manu, B.; Kudri, N.; Govardhanaswamy, H.S.
    In the present study, sequential anaerobic–aerobic treatment was used for the enhanced degradation of selected nitrophenols. Five identical reactors were used to assess the degradation of 2-nitrophenol and 2,4-dinitrophenol. Reactor 1 was used as control, and another four reactors were operated in anaerobic phase followed by sequential aerobic treatment. The performance of reactors was studied for nitrophenol concentrations of 5, 10, 20 and 40 mg/l and in next phase effect of redox mediators [lawsone and anthraquinone sulphonic acid (AQSA)], along with kinetics of degradation studied for 40 mg/l of nitrophenols. More than 98% degradation of nitrophenols was achieved at lower concentrations but for 40 mg/l removal percentage was reduced, and also COD inhibition was observed. However, with the addition of redox mediators, both nitrophenols and COD removal percentage were greater than 95% and 85%, respectively. Kinetics of degradation revealed that the rate of degradation was found to increase with the increase in concentration of redox mediators from 10 to 20 mg/l, and it was found that degradation was faster with the use of AQSA in comparison with lawsone solution. It indicates that use of redox mediators is favourable for the enhanced degradation of nitrophenols. Sequential anaerobic–aerobic treatment is possible potential treatment method for treating nitrophenolic wastewaters. © 2019, The Author(s).