A comparative study of anaerobic digestion systems to treat piggery waste

The work presented here concentrates on the use of a high rate Down-flow Stationary Fixed Film (DSFF) digester to treat piggery waste. Comparison of the results of the DSFF-type digester with the continuous stirred tank reactor (CSTR) showed that the former was capable of handling much larger loading rates and had higher rates of methane production than the latter. Results also indicated that microbial liquefaction of organic solids was the rate limiting step of the process in terms of conversion efficiency. Comparison of the results of the pilot and laboratory scale DSFF showed that the scale factor is not unfavorable, taking into account the large difference in diameter-height ratio and also the less important difference in specific support surface.