Rice Husk as Carbon Source and Biofilm Carrier for Water Denitrification

We investigated rice husk as the sole carbon source as well as biofilm carrier in the biological denitrification of wastewater in up-flow laboratory reactors. Fast startup of the reactor and high nitrate removal efficiency was observed. The highest denitrification rate (about 0.096kg/m·d) was achieved when flow rate and nitrate concentration were 41.4L/d and 25.0mg/L, respectively. Flow rate and nitrate concentration of the influent were observed to have a significant effect on nitrate removal efficiency. The reactor had the ability to accommodate a wide range of pH (6.5-8.5) and DO (1.5-4mg/L). A time-dependent decrease in nitrate removal efficiency was observed after 72 days of operation. And the addition of new rice husk brought about a rapid increase of nitrate removal efficiency. Results showed that rice husks can be an economical and effective carbon source for the nitrate removal process.