The Evaluation of Small Scale Composting of Human Feces for Household Application

Qian Li, Xiaochang Wang, Honglei Shi

 

ABSTRACT

In this study, in order to evaluate the efficiency of small scale composting of human feces based on the household application, 14-day batch experiments were conducted under ambient temperatures with sawdust as bulky matrix. The results showed that microbial communities changed significantly with the biomass decreasing in the first day, probably due to the die out of the pathogens existed in human feces. Meanwhile, the non-soluble organic matters was hydrolyzed to soluble fatty acids and resulted in the sharply decline of pH. However, with the adaption of microorganism, biomass increased fast in the 2nd day, and SCOD was degraded effectively accompanied with pH rising above 8.5. After available SCOD was depleted, temperature of compost decreased to ambient temperature, biomass and microbial communities tend to be stable. The total nitrogen loss during composting process was 15% and mainly resulted by ammonia gas emission, however the total phosphorous could be retained in compost completely. Although there was no thermophilic phase could be observed during composting process, the typical pathogens of feces die out in the first few days, meanwhile the seed germination index reached 93% at the end of composting, indicating the compost was manure. In addition, the Pseudomonas putida and Pseudomonas panipatensis showed strong signal in manure compost, both of them could function as soil inoculant and be exploited for soil bioremediation. Therefore, this small scale aerobic composting could achieve effective removal of organic matter and nutrient retention, the safe and stable final product could be used as fertilizer and soil conditioner. It would benefit the rural area where the feces could be treated in household scale and utilized for agriculture in-situ.

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doi:10.11912/jws.2016.6.4.113-124