Removal of nitrate from groundwater by heterotrophic denitrification using the solid carbon source

Abstract

Removal of nitrate from groundwater was investigated using biodegradable meal box (BMB) and poly(ɛ-caprolactone) (PCL) as carbon source and biofilm carrier. The experimental results show that nitrate in groundwater can be effectively removed using BMB and PCL as carbon source. Denitrification rates supported by BMB and PCL were 52.80 and 42.77 mg (NO3-N)/(m2·h), respectively, at 30°C and pH 7.5. The pH value of effluent ranged from 7 to 8, and NO2-N concentration was less than 0.1 mg/L. Compared with BMB, PCL could decrease nitrite accumulation; however, more significant influence of temperature on denitrification was observed for PCL as carbon source. Temperature constants for BMB and PCL were 0.045 and 0.068, respectively, at 10–30°C. Based on denitrification efficiency and cost, BMB is more suitable as a carbon source for denitrification of groundwater than PCL.