Maitha Al Majid Almheiri, James Peter Terry and Munawwar Ali Khan
Abstract
In this study, mineral sandy soils typical of the UAE were treated with two types of recovered organic waste (ROW): the autoclaved organic fraction (AOF) of municipal solid waste and anaerobically-digested wet and dry sewage sludges (SS), to assess their potential risks and benefits for application to soils in the UAE. Moisture content, pH, electrical conductivity, heavy metals (Cu, Cd, Pb, and Zn) and bacteriological properties of AOF and SS were examined. Results show that moisture content of untreated sandy soil improved after the addition of AOF and dry sludge, although salinity also increased. Heavy metal concentrations in both wet and dry sludge were found to be within allowable limits set by Dubai Municipality standards. However, for AOF recovered from municipal solid waste, cadmium and zinc concentrations exceeded allowable limits according to European standards for compost. AOF and dry sludge samples were free of bacterial growth, although the wet sludge showed a presence of coliforms, Pseudomonas aeruginosa and Salmonella bacteria. The properties of both AOF and dry SS show that there is potential for these types of recovered organic waste to be used as commercial organic fertilizers to improve sandy soils of the UAE for agriculture.