WATER & EFFLUENT TREATMENT
Dewatering of paint sludge with centrifuges
90 % cost reduction combined with a positive environmental impact
Wet absorption systems are the standard method to catch and discharge overspray from paint booths . For dewatering of its paint sludge a Polish paint shop purchased a cleaning centrifuge from Rösler . With sizable cost savings this investment paid for itself within the first year of operation . At the same time the dewatering of the paint sludge by centrifuge saves resources and is more eco-friendly .
In 1996 the painting job shop Hannex , located in Ordzin , Poland , started with the manual wet painting of components for household appliances . Since then the company has developed into a sophisticated operation with modern work places for manual paint applications as well as several fully automatic painting lines equipped with 6-axis robots and computer controlled paint supply systems . The company is coating metal , plastic and glass components with solvent- and water-based wet paint materials . Krzysztof Iwanicki , general manager at Hannex , explains : “ Besides the household appliance industry our customers also include automobile companies and their suppliers around the world ”.
A focus on costs and the environment
To ensure top quality and cost efficiency , the company utilises the latest paint application technologies from renowned suppliers . This helps reduce overspray but does not prevent it completely . The catching of the paint mist takes place with the classic Venturi wet absorption method . This uses atomised water to pick up the excess paint particles in the paint booth and discharge the paint / water mixture into three collecting tanks with a total volume of ten cubic meters . To maintain the stability of the process water various chemicals had to be added for controlling the pH value , for defoaming and for protection against bacteria infestation . The addition of coagulants and flocculants made sure that the paint particles were separated from the water and floated to the surface . The resulting sludge was then
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General manager Krzysztof Iwanicki explains : " The centrifugal process is so effective that we no longer need coagulants and flocculants to separate the sludge from the liquid phase . Furthermore , no other chemicals for stabilizing the water in the collecting tanks are required . This is why , beginning with the second year of operation , our operating costs for paint sludge treatment could be reduced by 89 %”.
removed from the surface and pushed into a separate container with a sludge scraper . Subsequently , it was disposed of . On average about 4 tons of sludge and dirty water accumulated per week . The professional disposal of this waste material was not only extremely expensive , but under environmental aspects the resulting high consumption of fresh water was not very eco-friendly . Last-but-not least , this paint sludge disposal system also caused an unpleasant odor , a real nuisance for the employees . Krzysztof Iwanicki continues : “ These disadvantages had annoyed me for quite some time . Therefore , I became very interested in paint sludge dewatering with a cleaning centrifuge and was grateful to Filip Kapela , the representative of Rösler Oberflächentechnik in Poland , informing me about this possibility in 2016 ”. After this first information a joint visit at the headquarters of the equipment manufacturer was arranged . During his visit Krzysztof Iwanicki was able to acquaint himself with the working principle and the performance characteristics of centrifugal filters for paint sludge dewatering . The general manager remembers : “ I immediately specified my requirements and subsequently decided to purchase a centrifuge RZ 120 M-V ”.
Efficient separation of solids and water from the paint sludge
The semi-automatic cleaning centrifuge can handle a volume of 120 liters per minute . A feed pump continuously feeds the process water into the centrifuge drum , rotating at a speed of 2,750 RPM . The high rotational speed ensures not only an excellent performance in terms of throughput , but it also ensures that very small and light-weight particles are deposited on the drum wall as solid sludge with a residual water content of 20 to 30 %. This represents a significant improvement over the sludge scraper with the
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