Study on the Protein Extraction from Excess Sludge by Papain Hydrolysis

The efficiency of excess sludge disintegration play a major role in protein extraction qualification. Hence, the use of optimal method is likely to promote the study of protein extractive rate in excess sludge. The objective of this study was to develop protein extraction by papain hydrolysis. There are four different factors were correlated to the protein yield during papain hydrolysis. These factors are protease content ,the ratio of solid to liquid, reaction time and temperature. The ratio of solid to liquid had a more significant influence on the total amount of protein than papain content. protein extraction concentration ranged from 8.23g/l to 9.98 g/l, and protein recovery rate was in the range of 42.3-52.7%.According to these data corresponded with high crude protein. In addition, the results showed that heavy metals of extractive protein was analysed below limited value. Thereby, papain hydrolysis treatment is recommended for practical extraction method because of its shorter extraction time. The nutrient composistion of protein recovered from excess sludge were feasible with animal protein feed.