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Water 2018, 10(2), 161; https://doi.org/10.3390/w10020161

Evaluation of the Digestibility of Attached and Suspended Growth Sludge in an Aerobic Digester for a Small Community

Department of Environmental Sciences, School of Agriculture and Environmental Sciences, University of South Africa, P.O. Box 392, Florida 1710, South Africa
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Received: 7 August 2017 / Revised: 14 November 2017 / Accepted: 21 November 2017 / Published: 7 February 2018
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Abstract

The aerobic sludge digestion process for waste sludge generated from suspended biomass (i.e., activated sludge process, ASP) and attached biomass (i.e., moving bed bioreactor, MBBR and modified packed bed biofilm, PBBR) reactors in a residential complex were analyzed. The rate of digestion with respect to different sludge characteristics generated through these various treatment processes were examined; the results revealed that waste sludge from ASP took 16 days to achieve complete digestion while MBBR and PBBR took nine and seven days, respectively. The most important factors influencing the sludge digestion such as sludge volume index (SVI), mixed liquor suspended solid (MLSS), and mixed liquor volatile suspended solid (MLVSS) were examined. The ASP which had the highest initial MLSS and MLVS took a longer time for digestion. Aerobic sludge digestion in all the treatment reactors was studied under laboratory scale conditions in batch experimentation to evaluate sludge characteristics and the rate of digestion as well as through a continuous bench scale pilot system to optimize the process parameters. Removal efficiencies of volatile solids (VS) 90.71% in ASP, 84.27% in MBBR and 84.07% in PBBR in aerobic digestion during batch mode were also observed. The study revealed that the aerobic sludge digestion process utilized in curbing sludge is not feasible application for a small community due to very long digestion times and a large amount of space although Packed Bed Biofilm (PBBR) used the lowest time (seven days) compared to the other systems. View Full-Text
Keywords: aerobic digestion; waste sludge; small community; activated sludge process; moving bed bioreactor; packed bed biofilm aerobic digestion; waste sludge; small community; activated sludge process; moving bed bioreactor; packed bed biofilm
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Azizi, S.; Kamika, I.; Tekere, M. Evaluation of the Digestibility of Attached and Suspended Growth Sludge in an Aerobic Digester for a Small Community. Water 2018, 10, 161.

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