Ami Patel and J.B. Prajapati
Abstract
Sewage disposal poses a serious challenge to municipal authorities and the problems related to pollution and safety are agitating the minds of policy makers, regulators and all citizens. Disposal of solid sewage waste for landfill is no longer considered to be a satisfactory environmental solution due to many health hazards linked with it. Therefore, alternative methods which can produce wealth from the waste are always in vogue. One such approach is application of sewage sludge on agricultural land as manure. However, before applying to land, it has to be made safe by some means and irradiation has been found to be most successful. The present investigation aims at finding effects of using irradiated sewage sludge as manure on soil and crop microflora. A total of 162 trials were conducted on plots of 4.0m x 1.8 m with three root crops and samples of soil before sawing and after harvest as well as crop it self were examined for various types of microbial counts. The total bacterial count of soil before sowing in all the samples ranged from 6.07-6.32 log cfu/g for different levels of manure while in the crops it ranged from 5.38-6.69 log cfu/ g. There was no significant difference observed in the values of coliform, yeast & mold count or anaerobic spore formers with respect to use of Farm Yard Manure (FYM), Irradiated Undigested Sewage Sludge (IUSS) and Non-irradiated Undigested Sewage Sludge (NIUSS). The study indicated that use of irradiated sewage sludge as manure does not affect the microbial count significantly. Moreover, Irradiation treated sewage sludge may serve to improve the fertility level of soil since it supported the growth of nitrogen fixing bacteria.