Generally, in a ...

Generally, in a well-functioning and designed biogas digester, the pathogen removal in the slurry is sufficient so the  treated sludge  can be reused for soil fertilisation. To increase the safety, it may be aerobically composted (or processed in a  sludge  drying or humification bed) before reuse .

A small-scale  biogas reactor  or  anaerobic digester  is an  anaerobic treatment technology that produces (a) a digested slurry ( digestate ) that can be used as a  fertilizer and (b)  biogas  that can be used for  energy .  Biogas is a mix of  methane , carbon dioxide and other trace gases which can be converted to heat, electricity or light. Small-scale biogas  reactors  are typically designed to produce  biogas  at the household or community level in rural areas. The airtight  reactors  are filled with animal manure from the farm. Kitchen and garden wastes can also be added and  toilets  can directly be linked to the  reactor  for co-treatment of  excreta .

A  biogas reactor  is an airtight chamber that facilitates the  anaerobic  degradation of black water ,  sludge , and/or  biodegradable  waste (e.g. animal manure, kitchen and garden wastes). It also facilitates the collection of the  biogas , a mixture of  methane  (CH4) and carbon dioxide (CO2) produced in the  fermentation  processes in the  reactor . The gas forms in the slurry and collects at the top of the chamber, mixing the slurry as it rises.The pressure exerted by the rising gas can be used to transport the gas to the collection vessel or directly to where it is going to be used. The  digestate is rich in  organics  and  nutrients , almost odourless and pathogens  are partly inactivated.