Technology offer: Wastewater treatment by electrocoagulation (EC)

Transcription

1 Technology offer: Wastewater treatment by electrocoagulation (EC)

2 Technology offer Wastewater treatment by Electrocoagulation (EC) Reference: TO-ECOAG SUMMARY The Department of Physical Chemistry (Applied Electrochemical Group LEQA) at the University of Alicante has a high experience and know-how to develop and carry out the removal of pollutants in wastewaters by electrocoagulation (EC). A pilot plant fully equipped with the necessary infrastructure and with ability to treat 100L/h of wastes is available in order to develop the pre-industrial phase and scaling-up of these processes. This technology could be of interest to several industries: chemical, tannery, textile, etc. TECHNICAL DESCRIPTION Applied Electrochemistry includes the use of electrochemical processes in any type of industrial application: synthesis of pharmaceutical products, batteries, effluent treatment, metallic electrodeposition, etc. The Department of Physical Chemistry at the University of Alicante is focused since several years on the investigation of new electrochemical processes and the transfer of knowledge and technology to the industry. Treatment of wastewater by EC has been practiced for most of the 20th century with limited success and popularity. However, in the last decade, this technology has been increasingly used in Europe for treatment of different types of industrial wastewater containing foodstuff waste, oil wastes, dyes, suspended particles, chemical and mechanical polishing waste, organic matter from landfull leachates, defluorination of water, synthetic detergent effluents, mine wastes and heavy metal containing solution. Coagulation is a phenomenon in which the charged particles in colloidal suspension are neutralized by mutual collision with counter ions and are agglomerated, followed by sedimentation. The coagulant is added in the form of suitable chemical substances. Alum [Al 2 (SO 4 ) 3.18H 2 O] is such a chemical substance which has been widely used for ages for wastewater treatment. The mechanism of coagulation has been the subject of continual review. It is generally accepted that coagulation is brought about primarily by the reduction of the net surface charge to a point where the coloidal particles, previously stabilized by electrostatic repulsion, can approach closely enough for van der Waal s forces to hold 2

3 them together and allow aggregation. The reduction of the surface charge is a consequence of the decrease of the repulsive potential of the electrical double layer by the presence of an electrolyte having opposite charge. In the EC process, the coagulant is generated in situ by electrolytic oxidation of an appropriate anode material. In this process, charged ionic species are removed from wastewater by allowing it to react with floccules of metallic hydroxides generated withing the effluent. The last stage of the R&D projects is carried out in the 120m 2 Pilot Plant that our group owns at the University of Alicante. This plant is equipped with vapour, cooling water, water softener, vacuum system, gases (air, nitrogen, CO 2, Ar, ). The plant owns a chemical reactor of 50L with a rectification column, an electrochemical filter press reactor, an electrodyalisis stack and an electro-floculation coagulation system. All these sytems are automated and can be used to develop and optimize various types of electrochemical processes: organic and inorganic electrosynthesis, electrodialysis, wastewater treatment by direct or indirect electrooxidation, electrocoagulation. The maximum production capacity in all cases is 1m 3 solution/day 3

4 Main Advantages OF THE TECHNOLOGY 1. EC requires simple equipment and is easy to operate. 2. Sludge formed by EC is easy to dewater. Also, EC produces low quantity of sludges. 3. Flocs formed by EC are similar to chemical floc, except that EC flocs contain less water, are and more stable, and therefore, can be separated faster by filtration. 4. The EC process has the advantage of removing the smallest colloidal particles, because the applied electric field sets them in faster motion, thereby facilitating the coagulation. 5. The gas bubbles produced during electrolysis can carry the pollutant to the top of the solution where it can be more easily removed. INNOVATIVE ASPECTS OF THE TECHNOLOGY - The EC cell is controlled electrically and have no moving parts, thus requires less maintenance - The EC process avoids uses of chemicals and so there is no problem of neutralizing excess chemicals. - EC produces effluent with less total dissolved solids (TDS) content as compared with chemical treatments. 4

5 Current state of the technology Pilot Plant scale tested. Intellectual property rights Secret Know-How. Market applications EC could be of interest to Industries that generate wastewater containing oil wastes, dyes, suspended particles, chemical and mechanical polishing waste, organic matter from landfull leachates, defluorination of water, synthetic detergent effluents, mine wastes and heavy metal containing solution. Cooperation sought The Department of Physical Chemistry is seeking for: Partners willing to introduce the electrocoagulation system in its facilities. R&D departments of any company interested in carrying out feasibility studies on the use, industrial or not, of this technology. Department of Chemistry Physics profile The group of Applied Electrochemistry of the Department of Physical Chemistry at the University of Alicante was created in 1983, the present staff consisting of one Professor, 2 Senior Lecturers, three Associate Professors, two electrochemical pilot-plant specialists, an electronic engineer and several post and pre-doctoral students. The research carried out by the group comprises: Electrocatalysis and Applied Electrochemistry (batteries, organic an inorganic electrosynthesis and water electrochemical treatment). 5

6 The aim of this group is to develop electrochemical processes for industrial purposes. Thus the research in this area field comprises different subjects. We have worked in the development of redox batteries and have built a 2 kw / 20 kwh accumulator based on Fe (III) / Fe (II) and Cr (III) / Cr (II) couples. Other subjects of research are electro-organic synthesis of fine and pharmaceutic chemicals and Electrochemistry applied to the environment. As a result of our work on this first subject, we hold several patents for the synthesis of l-cysteine derivatives and citiolone (one of them is a world-wide patent). To carry out electrochemical processes to industrial scales, we have designed and built an electrochemical pilot plant at the University in which, in co-operation with a Spanish industry, we have been able to synthesise 14Tm of carboxymethyl l-cysteine, a widely used pharmaceutical product. We have also taken part in a project for the recovery of lead from lead oxide secondaries such as used lead batteries (a BRITE-EURAM project). In this project we were in charge of the study and development of the cathodic process, lead deposition, to a pre-industrial scale, of the recovering of NaCl by electrodialysis and of the elimination of lead from the wastewater by electrochemical means. The aim was to demonstrate the feasibility of the process at an industrial scale. At the moment, we are developing a pre-industrial prototype for the electrochemical treatment of the wastewater of a textile industry. To do all this work, we have not only acquired a deep knowledge of Electrochemistry (both Fundamental and Applied) but also the expertise for developing different types of electrodes - single crystal, DSA, gas diffusion electrodes etc., and of different electrochemical reactors. This has all contributed to our wide experience in the development of electrochemical processes at a pre-industrial scale. CONTACT DETAILS Víctor Manuel Pérez Lozano Phone: Fax: otri@ua.es URL: Phone: Fax: otri@ua.es 6