Wastewater Treatment and Reuse for Urban Irrigation: A Case Study at Korle-Bu Vegetable Farm in Accra, Ghana.

Abstract

The use of untreated wastewater from open drains for irrigation in urban vegetable farms is increasing in Ghana due to high cost of treated water; meanwhile less than 50% of this wastewater undergoes prior treatment before disposal suggesting a potential health threat when used for irrigation. This research sought to develop a simple wastewater treatment system for reuse in irrigation. The mean chemical characteristics of wastewater were, Biochemical oxygen demand (325mg/l), Chemical oxygen demand (1072mg/l), Lead (0.35mg/l), As (1.6mg/l), Sodium absorption ratio (2.35meq/l). The recorded level of mercury was below detectable limit of 0.0005mg/l. Almost all parameters reduced by a significant percentage after treatment making it fit for use in irrigation. the mean difference in parameter of raw and treated wastewater were as follows; Electrical conductivity reduced by 79.6%, Total dissolved solids reduced by 40.81%, Total suspended solids reduced by 99.85%, S Turbidity reduced by 98.68%, Biochemical oxygen demand reduced by 99.65%, Chemical oxygen demand reduced by 89.04%, Lead reduced by 83.74%, Arsenic reduced by 99.16%, Escherichia coli reduced by 100% and Sodium absorption ratio reduced by 47.23%. At 95% confidence level (α=0.05). A t-test showed significant difference between the treated and intreated wastewater. The reduction rate was significant since most parameters considered conformed to regulatory standards for irrigation of vegetable crops after treatment. It is recommended that vegetable crop farmers adapt the system to prevent the spread of diseases caused by irrigating crops with contaminated water sources of similar characteristics.