CRITERIA TO ASSESS THE OPERATION OF ANAER OBIC PURIFICATION INSTALLATIONS FOR SACCHARIDE-CONTAINING WASTE-WATER .1. SPECIAL CONSIDERATION OF THE HYDROLYSIS AND ACIDIFICATION STAGE

The behaviour of the successive degradation stages in the anaerobic pu rification process of waste water (hydrolysis and acidification, aceto genesis and methanogenesis) was studied in the laboratory to obtain re liable process parameters and the optimal operating point of the respe ctive stage. The first of these degradation stages, hydrolysis and aci dification, was examined to see to what extent it can be tuned to a pr oduct spectrum favourable for the following degradation stage. The dis tribution of the acids formed in the acidification stage was found to be clearly dependent on the pH value and the spatial load. A pH value of 5 was found to be the optimal operating point in the acidification stage for the formation of easily methanizable compounds (ethanol, ace tic acid). The proportion of propionic acid difficult to degrade rises with increasing pH. The relationships found in the laboratory served to interpret the operating conditions of actual waste water installati ons.