Quantity and quality varies according to mill configuration and moisture content
Electricity generation
ESKOM does not report sludge volumes specifically
Tanneries
7 200 m3/a (DEAT, 1997) effluent plant sludges
Petrochemical industries
Data not available
Textile industry
Effluent plant sludge 240 m3/a
Wool washing sludges20 700 m3/a (DEAT, 1997)
Timber processing industry
Treatment sludges: 95 m3/a (DEAT, 1997) – excludes paper industry
Smith and Vasiloudis (1989) estimate sewage sludge generation in South Africa at 16.5 kg of dry sludge per person per year (Quoted by other WRC reports). DWA 1997 used 50g dry sludge per person per day in their calculations to get to a total of 309 556 t/annum (Herselman et al. 2005). Sewage sludge production in South Africa is therefore estimated at between 45 and 50g of dry sludge per person per day. The production of sludge can be calculated based on population figures as well as on the number of households with access to flush toilets connected to municipal sewer systems. The results of such calculations are presented in Table 23.