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Reuse of purified industrial waste water using membrane filtration

To update the existing wastewater treatment plant of rinse water from electroplating procedures. A combination of uf and nf or the ro system would be adopted for the improvement of wastewater quality, in order to reuse the treated water.

Industrial wastewater occurring at the manufacture Gorenje d.d., which gathers in their wastewater treatment plant is treated using conventional physical-chemical cleaning. There are maximum allowed values when determining physical and chemical parameters according to Slovenian regulation about the emission of substances at effluent from metal production (UL RS št. 6/07: 227), which are, in this case, stricter because of the low watercourse flow. At Gorenje d.d., 48 % of fresh water is consumed as cooling water and 34% as process water. In 2007, the total amount of wastewater generation at Gorenje d.d. was 115.000 m3. Aqueous solutions are used during each stage of the processing and pre-treatment of semi-finished goods, depending on the design process and technological lines, and various types and combinations of rinses, which mostly have a stream characteristic. Current working baths (concentrates), mainly from the pre-treatment procedures (mostly detergents) after being discharged are eliminated to be treated in the treatment plant, but the release of electrolytes (nickel, chromium) in galvanic treatment and release of baths for phosphating with lacquering, seldom appears. Therefore, this technological wastewater consist of: acids, bases, iron, chromium, nickel, zinc, aluminium, zirconium, and copper, phosphates, nitrates, nitrites, fluorides, sulphates, borates, silicates, carbonates, chlorides, biodegradable tensides, fats, salts of organics fats, salts of organics acids and particles of enamels. The used rinse water from electroplating procedure consists of above mentioned heavy metals and chemicals that can be detrimental to the health of organic bodies when exposed in the environment. At the same time, however, the rinse water has a great possibility for reuse if the heavy metals can be effectively removed and collected. From the viewpoint of environmental protection and resource saving, effective recycling and reusing of the metal wastewater is strongly expected. Closed-loop system or so-called effluent-free technology should be developed. Consequently, the operational costs would then be reduced. Only membrane separation, such as ultrafiltration (UF)/nanofiltration (NF) and UF/reverse osmosis (RO) are promising techniques, as already applied in many industries for water reuse and recycling. The selection of membrane technologies for treating the rinse water from electroplating effluent relies on costs based on the balance between flux and selectivity. Ultrafiltration (UF) has been successfully applied in many industries, but it has not been as widely accepted by the metal industry because it does not remove low molecular weight components. The rejection range from 30 to 90 % makes the direct use of UF impossible, and further filtration is required by either reverse osmosis (RO) or nanofiltration (NF). In RO, problems with fouling are present which result in low fluxes due to dense polymeric membrane use and poor separation. Also RO becomes less effective when osmotic pressure becomes too high to obtain a reasonable transmembrane permeate flux, caused by the high salt concentrations. When this occurs, NF provides a possible alternative to reducing the osmotic pressure with lower rejection of electrolytes by maintaining high dye rejections. However, in NF, both steric (sieving or size exclusion) and charge repulsion are used to reject species. For uncharged molecules, sieving is most responsible for separation; for ionic species, both sieving and electrostatic interactions are responsible for separation. The selectivity must be well controlled by membrane selection, as well as hydrodynamics, in order to reduce osmotic pressure building up to minimum yet maintaining very high dye rejections to produce acceptable colour removal. Because the osmotic pressures of the solutions are already high, even a slight increase in the wall concentration of the salt due to poor hydrodynamics or increased intrinsic rejection will decrease flux substantially. The project consortium would consist of three research/industrial partners from two different Eureka countries, two from Slovenia, and one from Belgium. The main participant and leader of the project would be the University of Maribor, Faculty of Chemistry and Chemical Engineering (UM, FKKT). The second Slovenian partner would be Gorenje Group, which has its headquarters in Slovenia, consists of the parent company Gorenje, d.d., and 93 subsidiary companies, of which 69 are based abroad. The third company is a Belgian membrane supplier called Pantarein bvba.
Acronym: 
IWW-REUSE
Project ID: 
5 854
Start date: 
01-07-2011
Project Duration: 
24months
Project costs: 
300 000.00€
Technological Area: 
Water Pollution / Treatment
Market Area: 
Water treatment equipment and waste disposal systems

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