Removal of biodegradable natural organic matter from seawater using biofiltration

Problems associated with biofouling are common in facilities that handle seawater, despite the low biodegradability of natural organic matter (NOM) in seawater.

In this Spanish–French work, a fixed-film aerobic biofilter is proposed as an effective unit to prevent biofouling in such facilities.

A packed-bed biofilter with an empty bed contact time (EBCT) of 6–11 minutes was employed. The results demonstrate that dissolved organic carbon (DOC) is reduced by 6%, and the biochemical oxygen demand at 7 days (BOD7) is reduced by up to 15%.

Analysis using liquid chromatography coupled with organic carbon detection (LC-OCD) revealed that biofiltration abates the low molecular weight (LMW) neutrals and biopolymer fractions by 33% and 17%, respectively.

However, fractionation with an ultrafiltration (UF) membrane showed that the biofiltration process is able to degrade the more biodegradable compounds that have molecular weights greater than 1 kDa and compounds with molecular weights of less than 1 kDa.

After biofiltration, the biological activity measured in terms of adenosine triphosphate (ATP) removal was reduced by 60%.

Finally, a test to evaluate the biofilm formation capacity of a water sample revealed reductions of approximately 94% when comparing biofiltered and non-biofiltered seawater.

Therefore, a fixed-film aerobic biofiltration process could be a useful treatment for the removal of biodegradable organic matter from seawater, and to improve water quality in terms of less biofilm formation capacity.

Desalination, Volume 316, 1 May 2013, Pages 8–16.