‏Methane biofiltration under different strategies of nutrient solution addition

Abstract

Two biofilters B1 and B2 packed with non-porous inorganic materials were operated for 283 days to eliminate methane (CH4), an important greenhouse gas. The biofilters ran under a constant empty bed residence time of 6 min at CH4 inlet loads of 7–63 g m−3.h−1. B1 was fed with a fresh nutrient solution every day (2 L d−1, flow rate of 1 L min−1) whereas B2 was supplied by a recycled nutrient solution from a 10 L tank. The flexibility of both biofilters were evaluated and compared in absence of nutrient solution for 35 days. Also, the performance of both biofilters under a different nutrient solution addition frequency (0.5 L every 6 h, flow rate of 1 L min−1) was investigated. B2 performed appropriately with an average removal efficiency of 62 ± 3% for an inlet load of 13 g m−3.h−1. B1 showed an average removal efficiency of 66 ± 4% for the same inlet load as B2. Analysis of nutrient solution in the recycle tank showed that the highest nutrient consumption over the time was at an inlet load of 63 g m−3.h−1. B1 and B2 were tolerant to nutrient solution deprivation for 25 and 21 days, respectively. Frequent addition of nutrient solution (0.5 L every 6 h, flow rate of 1 L min−1) improved the performance with corresponding average removal efficiency of 64 ± 4% for B1, compared to 57 ± 4% with nutrient solution addition of 2 L every 24 h with a flow rate of 1 L min−1, while no significant change was observed in B2.