Bioavailability reduction of cadmium in biosolids blended with limestone in agricultural utilization

At present, millions of biosolids are annually generated globally and their production is likely to rise due to the increasing population and expansion of sewage treatment plants in many countries. One reasonable and economical way to dispose of biosolids is to use them on land, especially agricultural area. This practice is becoming increasingly important in many countries because, biosolids are potentially a valuable resource containing 40-60% organic matter, macronutrients and micronutrients essential for plant growth (Chuasavathi et al., 2014; Bolan et al., 2003). However, the major problem in using biosolids for land application is that they can act as a source of metal input on land and form soluble metal complexes that are subject to leaching (Chuasavathi et al., 2014; Bolan et al., 2008). One suitable way to overcome this problem before applying them on land is to compost biosolids with other materials such as limestone. These materials can enhance metal immobilization. The cocomposted biosolids product can be safely used as a source of carbon and nutrients having a minimal impact on the bioavailability of heavy metals. Therefore, this study aims to investigate the bioavailability reduction of cadmium in biosolids blended with different concentration of limestone. (author)