Economical Study of Bioparticles used for Denitrification in Fluidized Bed Bioreactors (FBBR)

摘要

Economical study of different bioparticles for four Denitrifying Fluidized Bed Bioreactors (DFBBRs) using granulated maxi-blast plastic, granulated multi-blast plastic, natural zeolite, and lava rock were investigated to evaluate the feasibility of employing these media as carrier media or “bioparticles” for denitrification in a fluidized bed bioreactors. The work showed that the multi-blast plastic and natural zeolite achieved nitrogen and organic removal efficiencies of 99% and 87%, respectively whereas, the maxi-blast plastic and lava rock achieved removals efficiencies of 94% and 77%, respectively. Low biomass yields were observed for multi-blast plastic and natural zeolite of 0.12g VSS/g COD, while the yield for both the maxi-blast plastic and lava rock was 0.19 g VSS/g COD. Comprehensive economic evaluation of the fluidization energy consumption of each media considering the initial capital cost, operating and running cost, and replacement cost showed that the multi-blast plastic and maxi-blast plastic media were cheaper than natural zeolite and lava rock. Considering the average sphericity of each media, the particles with average sphericity of 0.9 i.e. multi-blast plastic and natural zeolite achieved nitrogen and organic removal efficiencies of 99% and 87%, respectively with a fluffy protruding biofilm whereas the particles with average sphericity of 0.5 i.e. maxi-blast plastic and lava rock achieved removals efficiencies of 94% and 77%, respectively with a patchy biofilm. Low biomass yields were observed for multi- blast plastic and natural zeolite with a sphericity of 0.9 of 0.12g VSS/g COD, while the yield for both the maxi-blast plastic and lava rock with sphericities of 0.5 and 0.6 respectively was 0.19 g VSS/g COD. Annualized unit media costs are mostly governed by fluidization energy costs which constitute 76%-97% of the total costs i.e. capital and media replacement costs are insignificant over the long-term. Considering denitrification performance and annualized overall media costs including fluidization energy, media loss, and capital cost, Multi-Blast (MB) plastic particle is the most suitable and economic media for the denitrification process in DFBBR, with a 20 years annualized capital and running cost of $1.56-$1.72 per kg, 30% cheaper than natural zeolite and 50% cheaper than lava rock.