Authors: Takashima M Kudoh Y Tabata N
Publish Date: 1996/09/01
Volume: 34, Issue: 5-6, Pages: 477-481
Abstract
The objective of this laboratory study was to improve the particulate solids decomposition of activated sludge by combining solidsliquid separation and posttreatment to anaerobic digestion The application of membrane separation has been shown to enhance the anaerobic biodegradability of sewage sludge In this study an anaerobic membrane digester with a volume of 51 and UF membrane of 177 cm2 was operated at 35 °C and a HRT of 30 days without considerable sludge wastage For the first 83 days the membrane digester was operated without posttreatment For the succeeding 41 days the membrane digester was combined with alkaline heat posttreatment This was done by taking out 50 ml per day of the digester sludge posttreating it under the condition of 01M NaOH and 175 °C for 1hr and returning it to the digester The particulate solids decomposition percentage averaged for each operating phase was 61 without the posttreatment and about 100 with the posttreatment These results indicate that the posttreatment was able to selectively destroy unbiodegradable components of the labcultivated activated sludge In addition because the feed activated sludge can be concentrated in the membrane digester the posttreatment requires less volume to be treated than pretreatment On the other hands the operation and application of this posttreatment combined process are limited by the allowable digester sludge level imposed by the membrane separation The problem to be solved is the deterioration of membrane permeate quality and methane production efficiency
Keywords: