Modified ADM1 structure for modelling municipal primary sludge hydrolysis.
This study elaborates the rate-limiting steps of particle disintegration/hydrolysis of primary sludge using methane production rate (MPR) curves from multiple batch experiments. Anaerobic batch degradation of fresh primary sludge showed a complex MPR curve marked with two well-defined temporal peaks. The first immediate peak was associated with the degradation of relatively readily hydrolysable substrates, while the second delayed peak was associated with the degradation of large-sized particles. For simulating the second delayed peak, it was necessary to consider a more elaborate particle disintegration/hydrolysis model. Based on the anaerobic respirograms of 17 runs in four datasets and using a substrate characterisation approach similar to activated sludge models (ASMs), the primary sludge was classified into three biodegradable fractions having different kinetics. These are (1) a hydrolysable substrate (X(Settle-I)) showing a degradation typical to slowly biodegradable compounds, (2) a substrate fraction (X(Settle-II)) having a degradation similar to lysis of biomass fraction and (3) a substrate requiring disintegration before hydrolysis (X(Settle-III)) representing the large-sized particles in primary sludge. Based on these results, modifications in the model structure of anaerobic digestion model no. 1 (ADM1) are proposed to improve the modelling of primary sludge solid degradation in anaerobic digesters.
Yasui
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Kurita Water Industries, 1-1, Kawada-Gochoyama, Nogi, Tochigi 329-0105, Japan. hidenari.yasui@kurita.co.jp
Goel
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Noike
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D000693:Anaerobiosis; D002264:Carboxylic Acids / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000378:metabolism; D006868:Hydrolysis; D008697:Methane / Q000378:metabolism; D008954:Models, Biological; D012722:Sewage / Q000382:microbiology*
D002264:Carboxylic Acids; D005232:Fatty Acids, Volatile; D012722:Sewage; D008697:Methane