Bioextract production using distillery slop as a carbon source for the anaerobic digestion process

Abstract

Distillery slop is the waste from alcohol manufacture, as from breweries or distilleries, which produce highly organic pollutants. This experiment studied bioextract that used distillery slop instead of molasses as a carbon source for the anaerobic digestion process. In this study, raw materials consisting of water spinach (Impomoea aquatica) residual, pineapple (Ananus comosus) residual, and fresh fish residual were used in the process to obtain the bioextract. The experiment was divided into three parts: a controlled experiment, mixed carbon sources (molasses and distillery slop), and a single carbon source (only distillery slop). The anaerobic digestibility of the bioextract was evaluated by a batch reactor at ambient temperature for a period of 90 days. The results of this study showed, by observing chemical oxygen demand (COD) at the initial and final processes, that the anaerobic digestive processes have a gradually decreasing rate throughout the fermentation period. The pH of the bioextract decreased at the beginning phase from pH 4 and increased to pH 7 in the last phase during the 90-day period. The results of a test with bean seeds showed compost maturity of over 80% following the organic fertilizer standard requirements of Thailand. With respect to variability, the optimal ratio generating the maximal compost maturity was 1:500 for the bioextract using only molasses as a carbon source and 1:250 for the bioextract using only distillery slop as a carbon source.