Scale down and optimization of olive mill wastewaters decolorization by Geotrichum candidum

Microbiol flora acclimated in continuous pilot scale bubble column fed with OMW was analysed. The most efficient isolated fungus was identified to white-rot fungus Geotrichum candidum. Decolorization of OMW by Geotrichum candidum was investigated by using Hadamard's matrix for screening the important parameters and optimize them in order to control the biological decolorization. Agitation favours the conversion of COD removed into Geotrichum candidum biomass especially with high arthoconodia and few mycelium. Dilution of OMW and aeration enhanced the mycelium growth and rammification which that allowed polyphenols hydrolysis and then a decolorization. The initial pH of OMW is suitable for its decolorization by Geotrichum candidum growth. Ammonium sulfate concentrations tested with different OMW dilutions showed that the COD:N:S ratio of 100:5:2 is suitable for higher black colour removal. With optimized conditions Geotrichum candidum growth on OMW in laboratory scale bubble column, the OD removal reached 70% and all fractions of polyphenolic compounds of OMW were oxidized.