Membrane Filtration of Olive Mill Wastewater and Exploitation of Its Fractions

Abstract

Olive mill wastewater (OMW) produced from small units scattered in rural areas of Southern Europe is a major source of pollution of surface and subsurface water. In the present work, a treatment scheme based on physical separation methods is presented. The investigation was carried out using a pilot‐plant unit equipped with ultrafiltration, nanofiltration, and reverse osmosis membranes. Approximately 80% of the total volume of wastewater treated by the membrane units was sufficiently cleaned to meet the standards for irrigation water. The concentrated fractions collected in the treatment concentrates were characterized by high organic load and high content of phenolic compounds. The concentrates were tested in hydroponic systems to examine their toxicity towards undesired herbs. The calculations of the cost of the overall process showed that fixed and operational costs could be recovered from the exploitation of OMW byproducts as water for irrigation and/or as bioherbicides.

Fundamentals and Technoeconomical Analysis of Exploitation of Olive Mill Wastewater to Highadded Vale By-Products

“…These methods were investigated in previous work [10,11] through a systematic parametric study changing accordingly the operational parameters, such as temperature, pressure, ionic strength and initial pH of different source of OMW, size of membranes (pore diameter), etc., in order to lead to a higher separation of toxic fraction from the nutritious one. Different fractions were derived from the whole process: a nutritious fraction as pre-or after-UF concentrate containing the larger components of the solution in terms of molecule size, a toxic fraction as RO concentrate containing the main part of phenols (ecological herbicide), a plant nutritious fraction as RO permeate containing the inorganic salts (fertilizer), and almost pure water for recycling/or irrigation or for free disposal to aqueous acceptors (lakes, rivers or sea).…”

“…Provided that the fixed cost for the installation of OMW treatment systems seems to be inelastic, operational cost reduction may be attained through the exploitation of the waste byproducts. The proposed separation techniques (prefiltration, ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO)) of the OMW treatment using membranes filtration have already presented in a previous work by the authors [10,11]. The idea of using membrane technology is revisited in the present work in which a new costeffective system for complete exploitation of OMW is suggested, offering a viable solution to the problem of OMW disposal.…”

“…This goal was succeeded by applying a conceptual design to find the best process and estimate the optimum design conditions. After definition of the operational parameters, the process flowchart was constructed via a hierarchy of design decisions, namely structure of input-output, recycling, separation and thermal integration [10].…”

“…Total operational cost (taxes exclude), OCʹ′: 1,008,000 €/yr 3.4 Economical potential -Assessment of the investment Production of an amount of 50,000 t/yr OMW treatment gives [10][11]: 5% nutritious fraction: 2,500 t/yr 15% toxic fraction: 7,500 t/yr Pure water for recycling or irrigation: 40,000 t/yr…”

“…Use of the proposed separation techniques produces byproducts that might have high additional benefits. A pilot plant was developed in an olive mill operating in Achaia region (Patras, Greece) during an olive harvesting season [10,11]. A feasibility-exploitation study was performed to estimate if the depreciation of the expensive investment may be done in a short period.…”