Abstract
Sewage sludge from ERWAT (East Rand Water
Care Company) was investigated to determine its potential as
a source of P. The raw sewage sludge was found to be a
potential source of P. At least 84% P could be leached from
the raw sewage sludge after 60 min using either HCl or
H2SO4. Selective precipitation of P as magnesium
tetraphosphate could be achieved using ammonia and
magnesium oxide to give yield a 92.2% pure magnesium
tetraphosphate and 9.8% P.