Anaerobic composting of pyrethrum waste with and without effective microorganisms

Abstract

This study investigated the use of effective microorganisms (EM) for enhancement of biogas production through composting of solid pyrethrum remains after extraction of pyrethrins (marc). The laboratory scale experiment involved composting of the waste as substrate mixed with EM at different ratios consisting of a control, substrate with EM at of 1:250, 1:500, and 1:1000 v/v. Results show highest production of biogas at EM ratio 1:500 v/v, while biogas produced at EM ratio of 1:250 v/v had the highest methane yield. It was also found that carbon to nitrogen (C/N) ratios for all mixtures fall within the optimal range (10:1 to 15:1) as compared to the control, which was out of range. This study was able to establish an optimal mixing ratio of the substrate and EM preferably to be 1:250 v/v at a dilution ratio of 1:4 m/m since it is observed to have the highest methane composition of 69% compared to the other treatments. The composted pyrethrum waste at all ratios can also be used as bio-fertilizer since the final COD of the compost is on an average of 134 g/L, suitable for soil conditioning.