USE OF CLEAN TECHNOLOGY IN SLUDGE TREATMENT UNDER SANDY SOIL APPLICATION

摘要

Radiation is a new technology for treatment of sewage and sludge. Radiationtechnology provides a safe approach to sludge recycling without introducing any environmental problem. During the last few decades numerous microorganisms have been shown to exert beneficial effects as a biological agent in controlling certain soil bome diseases and reducing the toxicity of heavy metals such as mycorrhizal fungi and pseudomonas bacteria. A study was carried out to assess the role of gamma radiation and biofertilizers to reduce pathogenic microorganisms and eliminate heavy metals uptake by cowpea plants grown in sludge amended sandy soil. Sludge samples were treated with different levels of each gamma radiation in comparison with lime in order to minimize the population densities of certain microbial groups of hygienic significance. Results showed that 10 kGy dose level of gamma radiation and 20% lime were the optimum treatments to reduce the microbial load of sludge. Another experiment was conducted in sandy soil to evaluate the role of biofertilizers (arbuscular mycorrhizal fungi and Pseudomonas fluorescens) as a biological agent to reduce the heavy metals uptake by cowpea plants grown in sludge amended sandy soil as compared with the role of the pretreated sludge with (20%) lime and (10 kGy) gamma radiation. Obtained results showed that biofertilizers treatments reduced the heavy metals uptake by cowpea plants. Although the addition of lime reduced the heavy metals uptake, the growth parameters of the plant were negatively affected. The greatest values of growth parameters and cowpea yield were observed under biofertilizers and gamma radiation treatments.