Modeling of solute transport and biological sulfate reduction using low cost electron donor

Serial data from soil-sawdust column experiments were used to develop a mathematical model to describe the biological sulfate reduction processes in porous media. The mathematical model numerically solves the equation of solute transport in one-dimensional saturated state. Solute transport is coupled to sulfate reducing bacteria sub model. Bacterial growth is assumed to follow double Monod kinetic equation. Two bacterial groups (X1 and X2) were described. Bacterial group X1 uses under aerobic conditions oxygen and under anaerobic conditions nitrate as electron acceptor. Under anaerobic conditions bacterial groups X2, use sulfate as an electron acceptor. Sulfate rich wastewater is usually deficient in electron donor and requires external addition of electron donors in order to achieve complete sulfate reduction. The organic carbon as electron donor is one of the most important factors that affect sulfate reduction bacterial activity. In this study the possible source of organic carbon is the solid organic carbon supplied to the system in the form of sawdust. The results of this study indicate that sawdust could be employed as low-cost materials to enhance the biological sulfate reduction processes in porous media. While the availability of organic carbon as electron donor is one of the most important factors that affect the sulfate reducing bacterial activity in porous media, this study demonstrates that using sawdust as a carbon source can improve the bacterial activity and increase the column permeability.