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An Integrated Membrane Process for Oily Wastewater Treatment, Water Reuse and Valuable By-Products Recovery

Final Report Summary - O-WAR (An Integrated Membrane Process for Oily Wastewater Treatment, Water Reuse and Valuable By-Products Recovery)

Executive Summary:
O-WaR was a 24-month project, partially funded by the EC under the FP7 programme, aimed at developing an integrated process able to efficiently remove highly emulsified oil from wastewater, to reuse treated wastewater, to recover valuable byproducts in wastewater and to reduce volumes of oily waste for disposal. A large amount of wastewater in the form of oil-in-water is generated in different industries such as vegetable oil, metal processing, transportation, petrochemical and oil and gas (produced water). These oily wastewater streams also feature high chemical oxygen demand (COD) and high suspended solids (SS). All relevant industries face the same problem: how to separate emulsified oil from water in a cost-effective way and to handle large volumes of oily waste in an economical way. The project involved 7 partners from 4 EU countries. The partnership included 2 RTD performers, 2 large industries and 3 SME.
The final report describes the characterization of various oily wastewaters, as well as the characterization of different membranes developed in the scope of the O-WaR project for processing these wastewaters. Several studies were then performed to (a) optimize the permeate flux using two different flux maintenance strategies (backpulse and backwash); (b) characterize the membrane filtration effectiveness; and (c) optimize the chemical cleaning procedures. A final concentration study was conducted under real conditions and several volatile compounds that may be present in the different wastewaters identified.
Six oily wastewater samples were received from four project partners: two olive mill wastewaters (from Sovena and Adventech), one sunflower refining wastewater (Sovena), one produced water (Liqtech) and two metal processing industry wastewaters (Venture). The samples were physically and chemically characterized. Parameters such as total solids, suspended solids, volatile solids, pH, conductivity, viscosity and particle size distribution were measured. Chemical oxygen demand, total organic carbon and several trace elements were quantified.
The silicon carbide surface properties of a substrate and coated membranes developed by Liqtech (1st and 2nd generation ceramic membranes) were characterized by scanning electron microscopy and contact angle measurements. Novel materials comprising titanium dioxide (TiO2), silicon dioxide (SiO2) and silicon carbide (SiC) semiconductors as well as a Fe-dopant, were also deposited over silicon-carbide substrates aiming to develop membranes with higher effectiveness and antifouling properties. After this characterization, different oily wastewaters were processed by ultrafiltration using the second generation silicon carbide (SiC) ceramic membranes developed. The filtration/rejection behavior of the membranes developed was characterized and the optimal flux maintenance strategies and cleaning procedures reported.
Even though several membrane modifications were tested, the second generation membranes, due to their high permeabilities and rejection results as well as reduced production time and manufacturing costs were addressed as the solution for the O-War project. The 2nd generation SiC membrane ensured high removal of total suspended solids and oil and grease, and it was found that the combination of backpulse every 10 minutes and backwash every 1 or 2 hours helps minimize fouling (maintaining flux), increases the percent rejection (improved permeate quality) and facilitates membrane cleaning (less chemicals used and higher membrane lifetime). To recover the membrane permeability acid and alkaline cleaning solutions should be employed in sequence at controlled temperature.
Furthermore, it was found that backpulse and backwash did not increase the energy demand costs and several volatile compounds were identified in the wastewater samples. Compounds such as toluene, ethylbenzene, o-xilene, styrene, indene and naphtalene may be removed to a certain extent due to adsorption on the membrane surface.
As an overall conclusion O-WaR introduced and successfully validated a conceptually simple approach for
Project Context and Objectives:
The final report describes the characterization of various oily wastewaters, as well as the characterization of different membranes developed in the scope of the O-WaR project for processing these wastewaters. Several studies were then performed to (a) optimize the permeate flux using two different flux maintenance strategies (backpulse and backwash); (b) characterize the membrane filtration effectiveness; and (c) optimize the chemical cleaning procedures. A final concentration study was conducted under real conditions and several volatile compounds that may be present in the different wastewaters identified.
Six oily wastewater samples were received from four project partners: two olive mill wastewaters (from Sovena and Adventech), one sunflower refining wastewater (Sovena), one produced water (Liqtech) and two metal processing industry wastewaters (Venture). The samples were physically and chemically characterized. Parameters such as total solids, suspended solids, volatile solids, pH, conductivity, viscosity and particle size distribution were measured. Chemical oxygen demand, total organic carbon and several trace elements were quantified.
The silicon carbide surface properties of a substrate and coated membranes developed by Liqtech (1st and 2nd generation ceramic membranes) were characterized by scanning electron microscopy and contact angle measurements. Novel materials comprising titanium dioxide (TiO2), silicon dioxide (SiO2) and silicon carbide (SiC) semiconductors as well as a Fe-dopant, were also deposited over silicon-carbide substrates aiming to develop membranes with higher effectiveness and antifouling properties. After this characterization, different oily wastewaters were processed by ultrafiltration using the second generation silicon carbide (SiC) ceramic membranes developed. The filtration/rejection behavior of the membranes developed was characterized and the optimal flux maintenance strategies and cleaning procedures reported.
Even though several membrane modifications were tested, the second generation membranes, due to their high permeabilities and rejection results as well as reduced production time and manufacturing costs were addressed as the solution for the O-War project. The 2nd generation SiC membrane ensured high removal of total suspended solids and oil and grease, and it was found that the combination of backpulse every 10 minutes and backwash every 1 or 2 hours helps minimize fouling (maintaining flux), increases the percent rejection (improved permeate quality) and facilitates membrane cleaning (less chemicals used and higher membrane lifetime). To recover the membrane permeability acid and alkaline cleaning solutions should be employed in sequence at controlled temperature.
Furthermore, it was found that backpulse and backwash did not increase the energy demand costs and several volatile compounds were identified in the wastewater samples. Compounds such as toluene, ethylbenzene, o-xilene, styrene, indene and naphtalene may be removed to a certain extent due to adsorption on the membrane surface.

Project Results:
Detailed informaiton on the achievements/results of the project per workpackage (WP) is provided in
the attached document.
Potential Impact:
The final result of the O-WaR project is a fully automated treatment system for oily waste waters. During the first reporting period special emphasis has been on understanding especially the olive oil production method and the water streams associated with this production. Due to the large seasonal variations in this type of production technologies for this type of industries needs to be able to handle large variations, and stand still for prolonged periods of time. At the same time the waste waters has never been seen as a product, but only a waste that has to handled. During the initial periods of the project the technology providers that are not experienced within this field had to apply resources to get this thorough understanding. As this knowledge now has been established the goal of the project seems even clearer than prior to start-up of the project, a setup that can handle the highly variable water streams, a system that can contribute to re-use of an important organic source and finally a system that can help the producers to be able to discharge their water to local water bodies, rather than paying large sums to discharge to local waste water treatment plants that are not constructed to handle neither this water type nor the volumes. Such a system has huge possibilities within an agricultural area that are struggling with prices and legislation. At the same time the thorough understanding of the water and requirements can be a withal part of introducing the solution on the market, as the individual customers are small and therefore do not have expert knowledge within the field. For the metal processing industry the same setup will help the involved industries to discharge their water, and thereby enabling them to extending their production without having large problems with legislation.
List of Websites:
http://o-war.eu/
Main contact
Head of Projects LiqTech International, Haris Kadrispahic
+4531232940
hak@liqtech.com
CTO LiqTech International, Project Coordinator, Johnny Marcher
+4531135517
jom@liqtech.com