Usage of Untreated Sewage Effluent for Irrigation and its Impact on Vegetables Quality

City effluent from Pakistan's third largest city (Faisalabad) is used as supplementary irrigation water to produce vegetables for human consumption. This paper reports a study to commence the assessment of risks and opportunities associated with this practice, with emphasis on cadmium (Cd), which is a toxic heavy metal that can enter the food chain as an impurity in vegetables. Cadmium and other properties were measured in typical effluents, four soils and a range of vegetables in the absence of fertilizer additions. It was found that the city effluent increased soil salinity, sodicity and cadmium concentrations. The Cd concentrations in the vegetables were also above those normally associated with suitability for human consumption. There were suggestions that soluble Cd concentrations in the effluent could be lessened by the addition of lime, concurrently lowering the sodium adsorption ratio of the effluent.