Collaborative research at Rhodes University, South Africa on the enzymology of anaerobic bio-reaction (digestion) has been in progress for several years.
The research illustrates the enormous complexity of the bio-reactions which need to be understood, and shows why ‘simple’ commercial guesstimates of microbial/enzyme/nutrient mixture requirements are extremely unlikely to be based on adequate research on this particular form of digestion.
From work based primarily on investigation of the enzymology of anaerobic bio-reactors designed for the accelerated digestion and hydrolysis of primary sewage sludge under sulphate reducing conditions, the low-cost high-efficiency the Rhodes BIOSURE process was established.
Further work has focused on the hydrolases of the hydrolytic or fermentative group of bacteria, which has found that the activities of all the enzymes (except for alpha-glucosidase) are dramatically enhanced in the presence of sulphide which is produced by sulphate reducing prokaryrotes, which are bacteria that live in symbiosis with the hydrolytic, acidogenic, acetogenic and methogenic bacteria in anaerobic digestion.
That there was an 80% reduction in solids and a 97% reduction in chemical oxygen requirement (COD) when two particular hydrolytic enzymes were added as a mixture. But the same enzymes used alone had little or no impact on sludge solubilisation The group has therefore made very interesting discoveries which could lead to ‘greater methane yields, lower sludge liquors, and a significant reduction in the requirements for and costs of digested sludge dewatering and disposal’. This clearly has implications for extending the life of pit latrines, as well as the possibility of considerably reducing the costs in conventional wastewater treatment plants.
Roman, H.J., Burgess J.E. and Pletschke, B.I. (2006). Enzyme treatment to decrease solids and improve digestion of primary sewage sludge. African Journal of Biotechnology [online]. Vol 5 , No 10 pp 963-967.
26 Apr 2010 03:39