Anaerobic decomposition of algae

The major objective was to determine the rate and extent of algal degradation under simulated natural conditions. Decomposition of heterogeneous and unialgal cultures was studied under dark, anaerobic, constant-temperature laboratory conditions. Effects of high sulfate concentration, bacterial seedings, temperature, pH, and cell composition on the rate and extent of degradation were evaluated. After 200 days, decomposition of algal cultures was essentially complete, and the undecomposed particulate organic matter remaining was termed the refractory organic fraction. This fraction ranged from 20 to 60% of the ash-free dry weight for various culture with an average of 40%. The decomposition of the biodegradable organic fraction could be adequately described by first-order decay kinetics with a range for the decay constant k of 0.011-0.032/d with an average 0.022/day. The rate and extent of degradation were similar to those found by other investigators under aerobic decomposition conditions.