Biological treatment of wastewater denitrification using a biofilm reactor with rice husk as an energy source

Two systems of biological treatment of denitrification in wastewater were evaluated, using anaerobic biofilm reactors with different external energy source. The first system used methanol as carbon source (conventional system) and the second, rice husk substrate, both operated with hydraulic retention times of 2.38, 5.56, 6.67, and 8.33 hours, with a nitrate feed of 40 mg _# ^$/ L. The system with rice husk substrate had greater efficiency in the removal of nitrates, with 97.58%, while the system with methanol has an efficiency of 93.46%, for the same time of retention. The two systems have a similar behavior in the removal of organic load, with a maximum efficiency of 94%. The concentration of biomass in the reactor with rice husk substrate is 14 286 mg/l, being higher than that of the reactor with methanol, which is 10 220 mg/l. The coefficient of biomass production, Y, is 0.007 and 0.0045 for the reactor with methanol and with rice husk, respectively, which indicates a low generation of sludge.