The effect of lime stabilization on E. coli destruction and heavy metal bioavailability in sewage sludge for agricultural utilization

The addition of lime as Ca(OH)2 to sewage sludge to destroy pathogens( Escherichia coli), was evaluated also in relation to heavy metal bioavailability. The obtained results show that the use of calcium hydroxide at the dose of 3% effectively destroyed pathogens ensuring the stability at high pH values over long period and the duration of sewage sludge stabilization. In general, lime addition decrease the total exctractability of heavy metals indicating a reduced bioavailabity of these elements. This is particularly important for a safe utilization in agricultural soils to reduce the possible transfer of heavy metals to the food chain.