Denitrification modeling using natural organic solid substrates as carbon sources

Abstract

In recent years, Natural Organic Solid Substrates (NOSS) have been studied as economical and safe carbon sources for use in water denitrification. Although the denitrification results with NOSS have been satisfactory, the information of the processes involved in the NOSS-biofilm interface is still limited. In order to understand these processes, we developed a one-dimensional mathematical model of counter-graduate denitrification, with which we evaluated: the behavior of the biofilm adhered to NOSS and its effect on carbon release; transport and consumption of carbon; and transport and consumption of nitrate. For this purpose, Saccharum spontaneum L. was used as a reference NOSS, of which biocinetic and hydrolysis parameters were generated in previous denitrification studies. This paper presents the results of the mathematical modeling of denitrification, with NOSS as carbon sources, which was simulated with the AQUASIM program. The assumptions and simplifications defined allowed the theoretical prediction of denitrification in batch reactors and completely mixed with flow. The best simulations of the study were obtained under biofilm detachment conditions, where denitrification was greater than 80 %. The most significant parameters of this mathematical modeling were the net yield of bacteria (Y_h) and hydrolysis (k_h). These findings demonstrate the importance of posing conceptual and mathematical models of denitrification using NOSS. This study would be a first approximation of a mathematical model of counter-graduate denitrification, using NOSS as a carbon source and biofilm carrier.