Comparative values of various wastewater streams as a soil nutrient source

In order to assess whether wastewaters from different industries (winery, abattoir, dairy and municipal) could be used safely to irrigate agricultural crops, a pot experiment in glass house was conducted in a sandy clay loam soil (pH = 6.12) from South Australia. Different concentrations (0, 0.05, 5, 25, 50, 75 and 100%) of the wastewaters diluted in an ordinary tap water were applied to soils sown with sunflower and maize seeds, and the effect of these irrigation treatments were evaluated at the early crop growth stages by recording the biomass yields, plant mineral nutrient contents, and also the soil chemical properties. Results showed that the winery effluent reduced the early growth of maize and sunflower when applied without any dilution, but increased yields of both plants when applied at 25% dilution with tap water. At this dilution of the winery wastewater, 80% more dry shoot yield (DSY) of sunflower and 58% more DSY of maize were obtained in comparison to the application of 100% concentration of the wastewater. Abattoir wastewater showed the highest yields at 100% concentration. Furthermore, municipal effluent did not show any inhibitory effect on both the crops. It was observed that metal contents in both the crops were different due to the application of different wastewaters, but did not exceed any toxic level. This study demonstrated that abattoir wastewater as such, and winery and dairy wastewaters at appropriate dilutions could be used for irrigation in agricultural fields to enhance crop productivity.