Reduction Of Adverse Environmental Impacts Caused By Urban Sewage: Application Of Green Soil Fertilizers
Nazi Baversiha, Kamran Parvanak, Mahnaz Nasrabadi
This research was designed with the aim of feasibility study on the production of safe fertilizers from urban sewage sludge in Isfahan refinery and assessment of the nutritional value of produced fertilizers in comparison with standard. For this purpose, the effects of different ratios of sewage sludge and manure on different treatments (including: 0, 25, 40, 55, 70 and 85 % wt/wt) along with 15 % bulking materials (including dry residues of Pine trees and grass waste) were tested in a randomized complete block design with three replications for a period of 75 days. Then, the nutrients content of each treatment was measured according to standard methods. The results showed that the concentration of heavy elements in the vermicompost produced in all treatments was lower than the standard recommended by EPA. The concentration of nutrients (total phosphorus and potassium, organic carbon, iron, zinc, copper, manganese) was very high in different treatments up to the application level of 70%. However, with increasing sludge consumption from 70% to 85%, the C / N ratio decreased significantly. Based on these results, an application of 70% sludge with 15% manure and 15% bulking material in a vermicompost production site can be used to produce a biological fertilizer with high fertilizer value and reduces the accumulation of sludge and environmental damage.