Electrokinetic Supply of Nutrients in Soil Bioremediation

Abstract

Biodegradation processes in soil and groundwater often require a supply of nutrients. Pretreatment of soil with the addition of nitrogen compounds is often necessary to achieve the required C:N:P ratio. In addition, a uniform supply of these nutrients is essential for an effective technology. However, the difficulty in supplying the required nutrients increases in fine soil and for greater depths. Electrokinetics can be a cost-effective method for obtaining a more uniform distribution of nitrogen compounds. The laboratory scale tests were performed on natural soil that was supplied with three concentrations of ammonium nitrogen: 13 000 mg l−1, 1 000 mg l−1 and 100 mg l−1. The introduction of these nutrient solutions into the soil was performed by applying a DC electrical field for 27 days. The measurement of electrical parameters and the analysis of the cathode effluent permitted the monitoring of processes occurring in soil. The analysis of soil at the end of the experiment showed that the ammonium distribution in soil was relatively uniform and it was related to the initial concentration of the supplied liquid. The nitrate concentration was found to be the highest in the anode area. Results also showed that soil moisture content can be controlled by the electrokinetic method. Continuous measurements of electrical parameters showed the resistance changes in soil during nutrient application. Resistivity changes of the soil, especially in the cathode area, were observed.