ABSTRACT
Studies show that source separated excreta have a good fertilizing potential for improving crop production and soil quality, the encountered effects are similar or even exceed those of mineral fertilizers. The main challenges with agricultural application of excreta are the high pathogenic risks (especially of the faeces fraction), increased loss of nutrients and odour emissions. The use of lactic acid fermentation of excreta for improving its resource- oriented value as well the post-treatment stages via vermi-composting and micro-aerobic composting is reviewed. The review shows that lactic acid fermentation of excreta can increase its agricultural value by reducing the amount of pathogens, minimizing the nutrient loss and inhibiting the production of malodourous compounds. While pathogens as Enterobateriacea, Staphylococcus and Clostridium can be reduced by 7 log CFU g−1 during 710 days of fermentation, Ascaris may not be always efficiently removed. Direct application of lacto-fermented faeces to agriculture may be constrained by incomplete decomposition, high content of organic acids or insufficient hygienization. Post treatment by biochar addition, vermi-composting or thermophilic composting will contribute to stabilization and sanitizing of the material. The pot and field experiments on soil conditioners obtained by lactic acid fermentation and post treatment steps by composting and biochar supplementation demonstrate an increased crop yield and growth as well as improved soil quality in comparison to the unfertilized control or other types of fertilizers (e.g. mineral fertilizer, stored faeces, urine or cattle manure).
