3.3. Effect of the amount of Rid-X on the BSFL grease yield
Rid-X contains millions of natural active bacteria that facilitate in breaking down the solid organic wastes, and the active ingredients are cellulase, lipase, protease and amylase. For better utilization of organic matter in rice straw and RSW, microbial agents were added to improve the conversion efficiency, especially the degradation of cellulose and hemicellulose in the rice straw. Different concentration of Rid-X was added to mixture of RSW(80%) and rice straw (20%) for co-conversion.
The results (Fig. 2B) indicated that when the amount of Rid-X was added from 0.05% to 0.4% (w/w) into the substrate, the insect biomass and larval grease yield increased correspondingly,showing a positive relationship between Rid-X dosage and grease
accumulation. With the assistance of microbes and its associated enzymatic degradation, more nutritive from the substrate became available for the development of BSFL. Some microbes may also aid in the digestion of food. This phenomenon has also been confirmed
in the previous studies [19]. Although more data is needed, shorter production cycle may be expected by this co-conversion technology. However, when inoculum dosage was higher than 0.4%, the larval grease yield increased only slightly. It is indicated that the
optimal dosage of Rid-X for the co-conversion should be about 0.4%. Therefore, mixing ratio (8:2) and 0.4% of Rid-X addition was used as a reference for the further optimization by uniform design.