Flocculation and Nanofiltration Processes with Insight of Fouling Phenomena for the Treatment of Olive Mill Wastewater

Abstract

Olive oil production is one of the main agriculture activities in many Mediterranean countries and it usually produces huge quantities of wastewaters. The management, treatment and safe disposal causes serious environmental issues. The adverse characteristic properties of OMW, which are the main responsible of their hazardous disposal, generally do not permit the treatment only by biological processes. Combined innovative processes should be adopted to remove the various organic and inorganic hazardous compounds from these wastewaters. Among the typical olive mill wastewater (OMW) treatments the most widely used are: drying / evaporation, forced evaporation, thermal treatment, electrocoagulation, composting, lagooning, adsorption, powdered activated carbon, sand filtration, membrane filtration, precipitation / flocculation, distillation, electrolysis, co-composting, advanced oxidation processes (AOPs). To define an efficient pre-treatment and to overcome major obstacles of membrane treatment (fouling), economic organic coagulant has been tested. Chitosan, a natural linear bio-polyaminosaccharide, is obtained by alkaline deacetylation of chitin. The main purpose of this study was to investigate the effects of chitosan as coagulant aid to reduce phenols content, COD and TOC in OMW, in addition to control membranefouling, which is used in the sequential step of the treatment. A conventional jar test apparatus was employed for the flocculation tests followed by photo catalysis and membrane treatment includes Nano Filtration process by means of a pilot-scale plant.