Improved Combined Chemical and Biological Treatments of Olive Oil Mill Wastewaters

Abstract

A novel system was investigated, finalized to reduce the impact of highly polluting wastewaters, and based on combined actions of catalytic oxidations and microbial biotechnologies. Olive oil mill wastewaters (COD 10,000-100,000 mg O(2)/L) were oxidized up to 80-90% by stoichiometric amounts of dilute hydrogen peroxide (35%) and in the presence of water soluble iron catalysts, either Fe(II) or Fe(III), at concentrations up to 1% w/w and more, i.e., much larger than those reported for conventional Fenton processes. In the combined action, the mineralization activity of a selected microbial consortium was used to degrade residual volatile and nonvolatile organic compounds into CO(2) and biomass. The results of this search could suggest an improved operational methodology capable to reduce the potential impact of wastewater.

Bioremediation of olive oil mill wastewater and production of microbial biomass

“…This is consistent with data reported by other authors as regards the presence of antimicrobial substances in OMWW (Amat di sanfilippo et al 1987;Bressan et al 2004;Capasso et al 1995;Isadori et al 2004). Previous alkalineoxidative treatment made the OMWW easily fermentable by the various seeded microorganisms.…”

“…In fact untreated OMWW are able to change the microbial composition of the soil through their antibacterial activity (Borya et al 1995;Tardioli et al 1997) and to produce phytopathogenic effects due to their high toxicity (Bressan et al 2004). In recent years, some methods have been proposed for OMWW bioremediation, such as chemical or microbiological treatment (Fountoulakis et al 2002;Isadori et al 2004;Kissi et al 2001;Maullu et al 1999;RigoniStern et al 1988;Sayady and Ellouz 1993).…”

“…However, simple chemical or microbiological treatment cannot completely reduce OMWW pollution; furthermore the costs are too high and up to 85% of the organic substances, which could be recycled, are destroyed. Combining both chemical and biological treatment is believed to produce the best results (Bressan et al 2004). Untreated OMWW and other agricultural wastes have been proposed for the production of animal feed, although digestibility and nutritional value were found to be somewhat unsatisfactory (Cabiddu et al 2004;Oliveira et al 2006).…”

Catalytic wet air oxidation of olive mill wastewater

“…As a result, in the last few years, there has been a great effort to develop efficient treatment solutions for OMW. Biological treatments are ineffective in practice, but when combined with chemical or physical processes the reduction of the OMW pollution parameters can be drastically improved (Bressan et al, 2004;Fiorentino et al, 2004). Other solutions, such as advanced oxidation processes and/or physico-chemical processes, have also been developed.…”

Effects of Combined Chemical and Biological Treatments on the Degradability of Vulcanization Accelerators

“…and, to a lesser extent, Escherichia coli, were capable of methylating several thiols including MBT. In the modified Fenton process used here, which has been described extensively by us in a previous paper (Bressan et al 2004), the oxidation is carried out in the presence of large amounts of iron salts (concentrations, higher than 0.05 mol l −1 ) and therefore far beyond the amounts usually reported for conventional Fenton processes. Under these conditions, and contrary to common belief, oxidation of strongly-polluted wastewater is definitely competitive with the dismutation of hydrogen peroxide, so that almost all of the added hydrogen peroxide is consumed to perform the abatement of chemical oxygen demand abatement (COD), leaving very few organic compounds in the reaction mixtures.…”