Optimisation of a novel biofilm technology for the removal of nuisance odours and greenhouse gases at low temperatures

The emission of greenhouse gases from activities in the waste and wastewater sectors can cause both environmental concern and public opposition to these facilities. The novel Horizontal Flow Biofilm Reactor (HFBR), recently developed and optimised as a wastewater treatment technology, has been adapted and is being tested for its efficacy in treating such gases. Three pilot scale HFBR reactors (HFBR 1, 2 and 3) were used to treat methane (CH4)-contaminated air. The study was conducted over two phases (Phase 1, lasting 90 days and Phase 2, lasting 45 days). The reactors were operated at 10oC (which is typical of ambient air and wastewater temperatures in northern Europe), and were simultaneously dosed with methane-contaminated air and a synthetic wastewater (SWW). The influent loading rates to the reactors were 8.6 g CH4 m3 hr (4.3 g CH4 m2 TPSA hr; where TPSA is Top Plan Surface Area). Despite the low operating temperatures, an overall average removal of 4.63 g CH4 m3 day was observed during Phase 2. The maximum removal efficiency (RE) for the trial was 88%. Potential and in situ microbial activity rates were measured and indicated (i) that biofilm samples taken from various regions in the HFBRs had mostly equal CH4 removal potential and (ii) that in situ rates were dependant on the region from which samples were taken.  These results indicate the excellent potential of the HFBR to biologically treat greenhouse gases.