餐厨垃圾的黑水虻处理中含钙矿物及微生物对油脂转化效率的影响

黑水虻处理是近年来发展起来的一种餐厨垃圾的有效资源化方法,但由于黑水虻的生理特性,油脂类物质经常不能被彻底降解和去除,残渣仍有酸败气味,需堆肥化二次处理.为了提高油脂类成分的降解效率,提升黑水虻富集油脂的资源化能力,本研究拟以含钙矿物和微生物为主要辅助手段,通过向餐厨垃圾中添加湿重比例为0~10%的CaCO₃、0~10%的Ca(OH)₂、5%CaCO₃和菌液的混合物及6种不同菌液,研究含钙矿物和微生物对于油脂减量化和虫油转化效率的影响.结果发现,向餐厨垃圾中添加含钙矿物,能够显著调节和缓冲黑水虻处理过程中的环境pH值,但对增加油脂的去除效率和黑水虻油脂的转化能力没有显著作用.而且添加7%~10% 的CaCO₃对于餐厨垃圾的减量化率和黑水虻的虫产率有负作用,添加5%~10%的Ca(OH)₂会导致显著的幼虫死亡率.同时添加CaCO₃和菌液对于油脂的去除不利.仅添加微生物菌液是提高垃圾油脂减量化率和黑水虻油脂富集率的最有效方法.枯草芽孢杆菌NJZ菌株、地衣芽孢杆菌NY菌株、植物乳酸杆菌RS72菌株和粪肠球菌L102菌株,是提高黑水虻油脂转化效率的有效菌株.添加微生物后,黑水虻的虫油产率由对照组的10.4%提升至12.8%~14.4%,虫油富集率由对照组的93.9%提升至116%~130%.虫油富集率超过100%,说明餐厨垃圾中碳水化合物、蛋白质等非油脂成分的一部分转化为黑水虻的体脂,而微生物的辅助降解可能是强化这一过程的主要因素.但即使在接种微生物以后,虫沙中仍然有29%~44%的油脂在处理结束时剩余,说明餐厨垃圾中的油脂较难被彻底降解和利用.未来研究中,可以继续筛选高效降解油脂的微生物,与黑水虻共同处理餐厨垃圾,实现油脂成分的资源化全利用.

Effects of calcium mineral and microbial inoculum on the lipid conversion efficiency during food waste treatment by black soldier fly larvae

The food waste treatment by black soldier fly larvae (BSFL) is an effective method for nutrient recycle, which has been developed rapidly in recent years. However, due to the physiological limitation of BSFL, lipid substances in the food waste generally can not be fully degraded, and the residue frass still has rancidity odor and needs to be further composted. In order to improve the degradation efficiency of lipid component and elevate the lipid conversion rate of BSFL, calcium minerals and microorganisms were utilized in this study. Generally, 0~10% CaCO₃, 0~10% Ca(OH)₂ , 5% CaCO₃ with bacterial culture, and pure bacterial cultures were added to the food waste during the BSFL treatment. The effects of calcium minerals and microbial inoculum on lipid reduction and conversion rates were studied. The results showed that addition of calcium minerals to food waste could significantly adjust and buffer the environmental pH value, however limited effects were observed on the lipid removal and conversion efficiency. The addition of 7% ~10% CaCO₃ resulted in negative effect on the food waste reduction and BSFL yield. The addition of 5%~10% Ca(OH)₂ could lead to significant larval mortality. Moreover, the addition of both CaCO₃ and bacterial inoculum resulted in unreliable results of lipid removal. Addition of microbial culture alone is the most effective way to improve the lipid reduction and BSFL lipid enrichment rate. Bacillus subtilis NJZ, Bacillus licheniformis NY, Lactobacillus plantarum RS72 and Enterococcus faecalis L102 were effective strains for improving the lipid conversion efficiency. Following the microbial inoculation, the BSFL lipid yield increased from 10.4% to 12.8%~14.4%, and the lipid enrichment rate elevated from 93.9% to 116%~130%. The lipid enrichment rates were more than 100%, indicating that part of the non-lipid components, e.g. carbohydrate and protein in the food waste were transformed into the larval body fat, and the microbial assistance might be the main factor that strengthen this effect. However, even with the microbial inoculum, there are still 29%~44% of the lipid in the food waste remained in the frass by the end of the treatment, indicating that the lipid component is difficult to be thoroughly degraded or recycled. Thus, it is highly recommended to screen microorganisms with high lipid degradation ability, in order to use them associated with BSFL, to achieve complete lipid conversion during food waste treatment by the BSFL.