ABSTRACT
The use of sulfur and limestone autotrophic denitrification (SLAD) systems has been studied increasingly due to its reliability, high nitrate removal efficiency and cost effectiveness. SLAD processes for the ex situ treatment of nitrate-contaminated groundwater have been studied mostly in Europe. In the US, only a few researchers have conducted research on autotrophic denitrification systems. According to van der Hoek et al., most researchers counteract biofouling by frequent backwashing in the SLAD systems except for in The Netherlands where van der Hoek attempts to restrict backwashing to a very low frequency. To determine the optimum operating conditions of SLAD reactors, four individual column reactors were operated utilizing different influent nitrate-N concentrations. The quasi-steady-state experiment started at the highest hydraulic retention time (HRT) and was reduced to the lowest HRT. To experimentally verify the biofouling within the SLAD reactors, the biofilm thickness distributions were measured using microelectrode techniques as reported by Tian C. Zhang and M. Bishop.
