Biodegradability of wastewater and activated sludge organics in anaerobic digestion


Show simple item record Ikumi, D S Harding, T H Ekama, G A 2018-03-26T11:54:56Z 2018-03-26T11:54:56Z 2014
dc.identifier.citation Ikumi, D. S., Harding, T. H., & Ekama, G. A. (2014). Biodegradability of wastewater and activated sludge organics in anaerobic digestion. Water Research, 56, 267-279. doi:10.1016/j.watres.2014.02.008
dc.description.abstract The investigation provides experimental evidence that the unbiodegradable particulate organics fractions of primary sludge and waste activated sludge calculated from activated sludge models remain essentially unbiodegradable in anaerobic digestion. This was tested by feeding the waste activated sludge (WAS) from three different laboratory activated sludge (AS) systems to three separate anaerobic digesters (AD). Two of the AS systems were Modified Ludzack – Ettinger (MLE) nitrification-denitrification (ND) systems and the third was a membrane University of Cape Town (UCT) ND and enhanced biological P removal system. One of the MLE systems and the UCT system were fed the same real settled wastewater. The other MLE system was fed raw wastewater which was made by adding a measured constant flux (gCOD/d) of macerated primary sludge (PS) to the real settled wastewater. This PS was also fed to a fourth AD and a blend of PS and WAS from settled wastewater MLE system was fed to a fifth AD. The five ADs were each operated at five different sludge ages (10–60d). From the measured performance results of the AS systems, the unbiodegradable particulate organic (UPO) COD fractions of the raw and settled wastewaters, the PS and the WAS from the three AS systems were calculated with AS models. These AS model based UPO fractions of the PS and WAS were compared with the UPO fractions calculated from the performance results of the ADs fed these sludges. For the PS, the UPO fraction calculated from the AS and AD models matched closely, i.e. 0.30 and 0.31. Provided the UPO of heterotrophic (OHO, fE_OHO) and phosphorus accumulating (PAO, fE_PAO) biomass were accepted to be those associated with the death regeneration model of organism "decay", the UPO of the WAS calculated from the AS and AD models also matched well - if the steady state AS model fE_OHO = 0.20 and fE_PAO = 0.25 values were used, then the UPO fraction of the WAS calculated from the AS models deviated significantly from those calculated with the AD models. Therefore in plant wide wastewater treatment models the characterization of PS and WAS as defined by the AS models can be applied without modification in AD models. The observed rate limiting hydrolysis/acidogenesis rates of the sludges are listed.
dc.source Water Research
dc.subject.other Municipal wastewater
dc.subject.other Unbiodegradable particulate organics
dc.subject.other Primary sludge
dc.subject.other Activated sludge
dc.subject.other Endogenous residue
dc.subject.other Anaerobic digestion
dc.subject.other Plant wide modelling
dc.title Biodegradability of wastewater and activated sludge organics in anaerobic digestion
dc.type Journal Article 2016-01-20T13:22:56Z
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Engineering & the Built Environment en_ZA
dc.publisher.department Department of Civil Engineering en_ZA
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