摘要:Improving the soil quality with organic matter content and presence of
elements such as N, P and K are some of sewage sludge benefits. Adjusting
carbonaceous materials such as plant wastes to dewatered sludge compost
increases its moisture and improves C/N ratio. So dewatered sludge has low C/N
ratio and should be mixed with bulking agents. This study was performed in a
three months period of the year 2002, in laboratory of Chemistry of Water and
Wastewater in the School of Public Health of Isfahan University of Medical
Science, to determine the C/N ratio and heavy metals concentration of bulking
agents in sawdust, leaves, rice hulls and dewatered sewage sludge. The results
showed that concentration of chromium and cadmium in the mixture of dewatered
sewage sludge and bulking agents was lower than the standard level. Means of
cobalt(115.44 mg/kg),nickel(57.44 mg/kg)and zinc(273.48 mg/kg) concentrations
were maximum in dewatered sludge but mean concentration of cobalt (25.66 mg/kg)
in rice hull samples and mean zinc( 8.99 mg/kg) and nickel (5.106 mg/kg)
concentrations in sawdust samples were minimum. The optimal conditions sewage
sludge composting, each kilogram of sludge needs 350 grams of saw dust, 470
grams of leaves and 388 grams of rice hull. Amount of heavy metals present in
the bulking agents is lower than the amount mentioned for the compost.
关键词:Bulking agents ، Dewatered sludge ، C/N ratio ، Heavy metals