Olive Oil Mill Wastewater Purification by Combination of Coagulation- Flocculation and Biological Treatments

Abstract

In order to define an efficient pre-treatment of Olive Oil Mill Wastewater (OOMW) to overcome major obstacles to biological treatment, various organic and mineral coagulants have been tested. In particular, the application of quicklime until a pH around 12 - 12.4 was reached, allowed the reduction of almost 37% of the initial COD, and approximately 88% and 71% of the colour and phenolic content of the waste. Hence, further biological treatments with an adapted aerobic consortium (AC) and a white rot fungus (WRF) strain were improved. The WRF Coriolopsis polyzona was more efficient than AC to reduce colour and polyphenols when the waste was prior diluted or pre-treated; however, it was less effective in COD removal. The combined treatment: lime - AC of OOMW having initial COD of 102 g l(-1) led to the elimination of about 77, 91 and 63%, of the COD, phenols and colour, respectively. Interestingly, the opposite combination AC - lime permitted better COD, phenols and colour reduction to respectively, 21, 11 and 11% of the initial values. This latter condition is technically recommended since only one step separation was needed and no pH correction was necessary before undergoing aerobic treatment. Moreover, the process would produce a sludge potentially rich in organic matter, and consequently, useful as an agricultural amendment or/and as an additive in animal nutrition.

Treatment of olive mill effluents by coagulation–flocculation–hydrogen peroxide oxidation and effect on phytotoxicity

“…Fe(III) at 1000 mg/L led to about 14%, 10% and 50% TSS, TP and COD reduction, respectively; these values were reduced to 5.6%, 7% and 10%, respectively, increasing Fe(III) concentration to 2000 mg/L, while further increase to 3000 mg/L gave no separation (data not shown). Jaouani et al [6] who studied OME treatment by Fe(III) coagulation reported the existence of an optimum coagulant concentration at which treatment efficiency was maximised; at concentrations greater than the optimum one, separation was suppressed and this was attributed to colloids being restabilised. PAC at a concentration of 1000 mg/L gave moderate TSS removal of about 60%, while COD decrease did not exceed 10%.…”

“…Coagulation with materials such as lime, alum, ferric chloride and ferrous sulphate has also been employed in OME treatment. Jaouani et al [6] recently demonstrated a two-stage process comprising aerobic degradation followed by lime coagulation, while Beccari et al [7] proposed a process comprising OME pre-treatment by means of lime coagulation and adsorption on bentonite followed by anaerobic digestion; they reported that pre-treatment was capable of enhancing considerably the anaerobic treatability of the original effluent. The effect of several OME pre-treatments such as lime or ammonium iron sulphate coagulation, resin adsorption and H 2 O 2 oxidation on subsequent anaerobic degradability was investigated by Zouari [8] who found that the pre-treated effluent was always more readily amenable to biodegradation than the original un-treated effluent.…”

Reduction of phenolics content and COD in olive oil mill wastewaters by indigenous yeasts and fungi

“…Activated sludge plants and other conventional biological treatment are barely proficient in removing such pollutants. A sequence of various physicochemical and biological treatments is thus commonly required to treat efficiently OOMW (Ranalli 1991; Khoufi et al 2004;Jaouani et al 2005). Microorganisms, in particular white rot fungi (WRF), were proposed as possible candidates for the biological step of OOMW treatment.…”

Caractérisation des margines issues d’une huilerie moderne et essais de leur traitement par coagulation-floculation par la chaux et le sulfate d’aluminium.

“…Les procédés physico-chimiques : coagulation-floculation (KISSI, 2002;JAOUANI et al, 2005;SARIKA et al, 2005), neutralisation avec la chaux (AKTAS et al, 2001;FLOURI et al, 1996;KHOUFI et al, 2000;RANNALI, 1991b;), électro-coagulation (INAN et al, 2004), adsorption sur charbon actif (ERSOY et al, 1998;MORINO-CASTILLO et al, 2001) et adsorption sur l'argile (AL-MALLAH et al, 2000AZZOUZI, 1997). …”