Current Status and Future Prospects of Small-Scale Household Biodigesters in Sub-Saharan Africa

Table 7

Feedstock and process parameters affecting digestate composition [80].

Feedstock parameter	Digestate composition impact	Process conditions	Digestate composition impact
Organic wastes	(i) Low organic content concentration in TS; (ii) Low content of total solids	High amount of fresh water	(i) High production of digestate; (ii) Low levels of salt and ammonia; (iii) Low TS content
Large amount of abattoir waste	(i) High concentration of nitrogen; (ii) High % of NH3 in total nitrogen	Recirculating liquid in large quantities (process water made from the liquid portion of digestate)	(i) Low production of digestate; (ii) Excessive salt/ammonia concentrations; (iii) A higher content of TS
High quantity of manure	(i) Low content of TS high nitrogen concentration	Short hydraulic retention time	(i) High quantity of volatile fatty acids; (ii) Organic content in TS; (iii) Low NH3 content in total nitrogen
Energy crops	(ii) High content of TS; (iii) High % of organics in TS (VS/TS ratio)