Integration of a nitrification bioreactor and an anoxic biotrickling filter for simultaneous ammonium-rich water treatment and biogas desulfurization.

A preliminary assessment has been carried out on the integration of an anoxic biotrickling filter and a nitrification bioreactor for the simultaneous treatment of ammonium-rich water and HS contained in a biogas stream. The nutrient consumption in the biotrickling filter was as follows (mol NO-N): 6.3·10 ± 1.2·10 mol PO-P, 0.04 ± 0.05 mol NH-N and 0.04 ± 0.03 mol K-K. Furthermore, it was possible to supply a mixture of biogenic NO and NO into the biotrickling filter from the nitrification bioreactor to obtain a maximum elimination capacity of 152 gHS-S m h. The equivalence between the two compounds was 1 mol NO-N equal to 1.6 mol NO-N. The biotrickling filter was also operated under a stepped variable inlet load (30-100 gHS-S m h) and outlet HS concentrations of less than 150 ppm were obtained. It was also possible to maintain the outlet HS concentration close to 15 ppm with a feedback controller by manipulating the feed flow (in the nitrification bioreactor). Two stepped variable inlet loads were tested (60-111 and 16-102 gHS-S m h) under this type of control. The implementation of feedback control could enable the exploitation of biogas in a fuel cell, since the HS concentrations were 15.1 ± 4.3 and 15.0 ± 3.4 ppm. Finally, the anoxic biotrickling filter experienced partial denitrification and this implied a loss of the desulfurization effectiveness related to SO production.