The use of a specific function to estimate maximum methane production in a batch‐fed anaerobic reactor

A readily biodegradable substrate was used to assess the value of using a mathematical function of y = y max exp m / x as a simplified method of determining the maximum methane production ( G max ) in a batch anaerobic reactor. Experimental results to test the method used three different initial substrate loadings in pre‐acclimatised completely mixed anaerobic reactors. Gas production was found to follow a typical trend that has previously been described by first order reaction kinetics; for the purpose of fitting the linearisation, it requires a value for maximum cumulative methane production. Use of the modified specific function to yield the equation G = G max exp m / t showed that the experimental gas production curve could be estimated with a high degree of similarity. This was confirmed by a statistical analysis using the method of residuals which gave a correlation coefficient ( R 2 ) greater than 0.97 between experimental and estimated values. Using a graphical linearisation of the specific function produced a simplified method of predicting G max . The value obtained was then used in a first order kinetic model to derive the specific coefficient rate ( K o ), which was in agreement with other methods used for its determination. Copyright © 2004 Society of Chemical Industry