Biodegradability of meat industry wastes under anaerobic and aerobic conditions

In this study the biodegradation kinetics and the different biologically degradable fractions (readily, slowly and inert fractions) of the organic wastes generated in a meat industry have been estimated under both anaerobic and aerobic conditions. Three of these could be degraded under both conditions, whereas one (pig/cow waste slurries) could only be aerobically degraded since the high ammonia concentration caused inhibition in anaerobic experiments. Mathematical models for anaerobic and aerobic degradations were used to estimate the readily (SS) and slowly (X) biodegradable fractions of the meat industry wastes. Using these models, a good agreement was observed between the calculated SS fractions for each waste under anaerobic and aerobic conditions, while the calculated X fractions in the aerobic tests were lower than in the anaerobic tests. The experiments, in combination with the modelling, showed that aerobic respirometric test may be used for predicting readily biodegradable fractions under both anaerobic and aerobic conditions provided that ammonia concentration is not significantly high. Thus, for complex organic wastes the length of experiments for estimating biodegradable fractions may be considerably reduced (in this case by 10–12 days).