Effect of wastewater irrigation of sweet sorghum on soil and plant

Abstract

The experiment was conducted at Isfahan East Waste Water Treatment in 2011 growing season by using a randomized complete block design with three replications. The treatments were managed for irrigation: municipal water, untreated waste water and treated waste water. Results showed irrigation with untreated and treated waste water had significantly higher biomass (86.00 t/ha) than municipal water (66.00 t/ha). Highest ethanol yield (6540 l/ha) was obtained for sweet sorghum irrigated with raw waste water. Both pH and P was accumulated in the soil irrigated with untreated and treated waste water. At the end of growing season the amount of Cd, Pb and Ni were accumulated in these soils. The amount of measured heavy metals in sweet sorghum grain, leaf and stem were significantly higher in untreated waste water than both municipal water and treated waste water. Number of coliform in untreated waste water was significantly higher than treated and municipal water. The number of coliform in grain, leaf and stalk for surface non- sterilized was higher than surface sterilized but it was less than 100 MPN 100 ml-1. Based on the results, in order to produce bioethanol without accumulation of heavy metals in the soil, it is suggested to plant sweet sorghum and irrigated with treated waste water.