Anaerobic degradation of organic materials: significance of the substrate surface area

• Published in: Water science and technology 2003-01, Vol.47 (12), p.231-238
• Main Authors: PALMOWSKI, L. M, MÜLLER, J. A
• Format: Article
• Language: English
• Subjects: Adsorption; Agreements; Anaerobic microorganisms; Anaerobic processes; Applied sciences; Bacteria, Anaerobic - enzymology; Biodegradation; Biological and medical sciences; Biological treatment of waters; Bioreactors; Biotechnology; Cellulose; Comminution; Degradation; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General purification processes; Hydrolysis; Industrial applications and implications. Economical aspects; Lignin; Measurement methods; Microbial degradation; Microorganisms; Nitrogen - chemistry; Organic Chemicals - metabolism; Organic materials; Organic matter; Particle Size; Particulate organic matter; Pollution; Specific surface; Substrates; Surface area; Surface chemistry; Waste Disposal, Fluid; Wastewaters; Water Pollutants - metabolism; Water treatment and pollution
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2003.0651

In anaerobic degradation of substrates containing mainly particulate organic matter, solids hydrolysis is rate-limiting. In these investigations, the particle size of various substrates was reduced by comminution to support hydrolysis. Two positive effects of comminution were observed. For substrates with high fibre content, which are particularly resistant to biodegradation, a significant improvement of the degradation degree was observed as a result of comminution. Secondly, for all substrates tested, and particularly for those rich in fibres, the degradation rate of comminuted samples was significantly higher. The first reason for both effects is an increase of the sample surface area. Several methods for measuring the specific surface area of organic materials, including particle size analysis, Nitrogen-adsorption and enzyme adsorption, were used and compared for the purpose of this study, where the surface area accessible to microbial enzymes is critical. The significance of the surface area in anaerobic degradation of particulate substrates was investigated through a kinetic model where the hydrolysis rate was based on the sample surface area. Good agreements were obtained between model and experiments carried out with samples of various specific surface areas. These results reinforced the significance of the sample area in anaerobic degradation processes. However, other effects of comminution responsible for the increased degradation degree and degradation rate were identified and discussed. These include: the increase of dissolved compounds due to cell rupture, exposition of surface areas previously inacessible for microbial degradation, and alteration of the sample structure such as the lignin-cellulose arrangements.