NO3−-N removal with sulfur-lime porous ceramic carrier (SLPC) in the packed-bed bioreactors by autosulfurotrophic denitrification

The performance of sulfur-lime porous ceramic carrier (SLPC) in the packed-bed bioreactors (PBBRs) was evaluated. SLPC showed the applicability of energy substrate as well as physical support to the microbial biofilm for the contaminated groundwater treatment. The PBBRs fed with influent concentration range of 20–60 mg NO3−-N/L also showed the maximum denitrification efficiency of 99.5% at the loading rate range of 0.22–1.2 kg NO3−-N/m3 SLPC/d. A comparison with the previous results showed that NO3−-N removal rates of the PBBRs were significantly higher than those of sulfur packed-bed reactors. The nitrous oxide content in the produced gas was found to be less than 1%. Good mass transfer of NO3−-N to the biofilm on sulfur surfaces and absence of clogging problems could be the main reasons for the higher NO3−-N removal rate in the PBBRs. Results presented here also constitute the usability of an innovative SLPC and suggest that the PBBRs with SLPC is suitable for post-denitrification of NO3−-N contaminated groundwater due to unnecessary external energy and alkalinity source.

► The feasibility of an innovative PBBR system was evaluated. ► Sulfur-lime porous ceramic carrier (SLPC) was used. ► SLPC supplied 2.0 g as CaCO3/kg SLPC/d by the dissolution of lime. ► Sulfate was generated 7.3 g SO42−/g NO3−-N reduced in the PBBRs. ► Maximum denitrification resulted up to 0.7 kg NO3−-N/m3 SLPC/d without alkalinity supply.