Effects of Rice Mill Wastewater on Cocoon Production and Total Population of Earthworm, Eisenia Fetida (Savigny 1826) under Laboratory Condition

Water scarcity can be overcome through the reuse of treated wastewater for irrigation especially in arid and semiarid regions. However, there are several potential environmental and health risks associated with this practices. Improved plant growth and nutrients for microorganisms are also gotten from wastewater which has high nutritive value. This study investigated the effect of rice mill waste water on cocoon production and total population of earthworm Eisenia fetida under laboratory conditions. A total of five hundred (500) clitella earthworms were used for this study. The physico-chemical parameters of the rice mill wastewater were analyzed using standard methods of APHA-AWWA-WEF (2000). The study on the cocoon production and total population of E. fetida were conducted from 0 to 100% wastewater (0, 25, 50, 75 and 100%) by serial dilution for a period of 60 days to assess the suitability of rice mill wastewater for irrigational purpose. The significant difference between treatments was tested by one-way ANOVA. The wastewater had an alkaline pH (8.5), low sulphate (0.95 mg/l), DO (3.10mg/l) and COD (2.0mg/l); moderate concentration of TDS (421mg/l), calcium (47.7 mg/l), phosphate(102.27 mg/l) and high concentration of conductivity (20.50 dsm-1), total solid (2550mg/l), total dissolved solids (2028 mg/l), total hardness (100 mg/l) and sodium (25.0 mg/l), earth population(53.2) At 50% of the wastewater usage there was a significant increase in cocoon production (24.24). On the basis of this research, it shows that rice mill wastewater should be either diluted to at least 50% or treated to make it suitable for irrigational purpose.