Dolomite limits acidification of a biofilter degrading dimethyl sulphide

The applicability of dolomite particles to control acidification in a Hypho microbium MS3 inoculated biofilter removing dimethyl sulphide (Me2S) was st udied. While direct inoculation of the dolomite particles with the liquid m icrobial culture was not successful, start-up of Me2S-degradation in the bi ofilter was observed when the dolomite particles were mixed with 33% (wt/wt ) of Hyphomicrobium MS3-inoculated compost or wood bark material. Under opt imal conditions, an elimination capacity (EC) of 1680 g Me2S m(-3) d(-1) wa s obtained for the compost/dolomite biofilter. Contrary to a wood bark or c ompost biofilter, no reduction in activity due to acidification was observe d in these biofilters over a 235 day period because of the micro environmen t neutralisation of the microbial metabolite H2SO4 with the carbonate in th e dolomite material. However, performance of the biofilter decreased when t he moisture content of the mixed compost/dolomite material dropped below 15 %. Next to this, nutrient limitation resulted in a gradual decrease of the EC and supplementation of a nitrogen source was a prerequisite to obtain a long-term high EC (> 250 g Me2S m(-3) d(-1)) for Me2S. In relation to this nitrogen supplementation, it was observed that stable ECs for Me2S were obt ained when this nutrient was dosed to the biofilter at a Me2S-C/NH4Cl-N rat io of about 10.