Before the “dirty” process water coming from a mass finishing operation can be discharged to sewage, it must be cleaned to meet the legal discharge limits for hazardous materials. Likewise, for cycling the water back to the mass finishing process, the process water must also be cleaned. Uncleaned process water would cause a mass finishing process to collapse very quickly.
Rosler has more than 80 years of surface finishing expertise. In that time, we’ve developed countless efficiencies in both the design of our equipment and the processes they support. Centrifuge technology has long been an effective and cost-efficient tool, not only for cleaning the process water, but also for reusing it for the actual mass finishing operation.
Previous Cleaning Methods
To a large extent, this technology has replaced traditional waste water cleaning methods. Until recently, the most common cleaning systems for mass finishing applications were settlement tanks and flocculation (“floc & drop”) systems.
In settlement tanks the “dirty” water is collected in big tanks. The solid particles suspended in the liquid settle to the bottom over time, creating a time-consuming and rather messy cleaning method.
Above all, this method does not meet the legal discharge limits for removing contaminants from the solution, including:
- COD values (chemical oxygen demand).
- Solid particles.
As a result, settlement tanks are rapidly being replaced by more environmentally friendly cleaning systems.
“Floc & Drop” Systems
“Dirty” process water is collected in a large tank in “floc & drop” systems. Flocculants are added to the water to coagulate the tiny solid particles and emulsified oil droplets into larger flocs. These flocs sink to the bottom of the tank and are then pumped to a filter press or bag.
Unlike settlement tanks, water discharged from “floc & drop” systems meets legal standards and can be discharged to sewage. These systems are very labor intensive and often rely on operator to ensure all steps are taken to meet the authorized discharge limits.
Other Methods & Special Uses
Evaporators and membrane filtration systems are occasionally used for mass finishing operations as well.
Except for settlement tanks, which are pretty much obsolete, the other waste water systems mentioned still have a place in mass finishing operations particularly for special applications. In general, these systems are costly and somewhat difficult to operate compared to centrifuges.
Above all, non-centrifugal methods do not allow the recycling of the cleaned process water for reuse in the respective mass finishing process!
In recent years, centrifuges (also called centrifugal filters) have proven to be the most effective, cost-efficient, and ecologically sustainable cleaning systems for the “dirty” process water generated in mass finishing operations.
Centrifuges are very easy to handle and require no special knowledge to operate them. Furthermore, they require no permits from local water authorities.
Centrifuge Recycling Schematic
They also excel when it comes to cost savings and consumption. Centrifuge technology can reduce the water and compound consumption in mass finishing operations by up to 95%. This saves not only money but makes a substantial contribution toward environmental sustainability in manufacturing.
In short, cleaning centrifuges represent a rare industrial equipment category, where economic benefits go hand-in-hand with ecological objectives and environmental stewardship!
The Rosler Way
“Finding a better way…” is more than a motto at Rosler; it’s our mission. The use of centrifuge technology in mass finishing operations is just one of our many innovations. Contact us today to learn how we can help solve your unique surface finishing challenges.
Previous posts in the Centrifuge Technology series include:
- Part 1 – “Water Cleaning Systems Replace Outdated Methods.”
- Part 2 – “Operational and Economic Benefits of Recycling Process Water.”
- Part 3 – “Mechanics and Limitations of Water Recycling.”
- Part 4 – “Pre-Conditions and Consumables Enhance Process Efficiency.”
Upcoming posts in the Centrifuge Technology series will include:
- Part 5 – “Potential Issues and Remedies for Water Recycling.”
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