ABSTRACT
Human faeces from urine diverting dry toilets can serve as valuable soil conditioners. For a successful agricultural application, an efficient pathogen reduction needs to be ensured, with no negative effects on the plants. This study assessed the efficiency of lactic acid fermentation combined with thermophilic composting on pathogen removal from human faeces and the post-treatment effects on germination and growth of radish (Raphanus sativus) and tomatoes (Lycopersicum esculentum) compared to lactic acid fermentation combined with vermi-composting and the control. The NH4+-N/NO3−-N ratio of 2.99 and 3.6, respectively, indicated the obtained compost and vermi-compost was not yet mature. A complete reduction in the concentration of all investigated bacterial indicators (i.e. coliforms, Escherichia coli, Enterococcus faecalis and Clostridium perfringens) from 5-7 log CFU g−1 to below the detection limit (< 3 log CFU g−1) was achieved after lactic acid fermentation combined with thermophilic composting. Lactic acid fermentation combined with vermi-composting also contributed to pathogen die-off, but coliform bacteria were reduced to only 5 log CFU g−1. Compost obtained after lactic acid fermentation combined with thermophilic composting to seeds of radish had a higher germination index than vermi-compost obtained after lactic acid fermentation combined with vermi-composting (90 versus 84%). Moreover, significantly bigger average fruit weight and total biomass per tomato plant (P<0.05) were obtained after compost amendment compared to vermicast or the unamended control.
