Metal plating and finishing requires an ample amount of various chemicals for an efficient operation. However, the chemicals found in these wastewater streams are not only expensive to remove but also potentially damaging to the environment. Read on for tips for avoiding these negative impacts as well as industry best practices for wastewater treatment and disposal.
Collecting the Right Information
When it comes to metal finishing wastewater treatment, it’s important to understand certain baseline information. Four areas to keep in mind are rinse tanks, ventilation systems, acid cleaners and acid etches, and alkaline cleaners. Making a layout of these areas to collect appropriate information can help clarify the process and build awareness of initial costs.
The metal finishing industry involves processes that use more water than many other industries, resulting in stringent EPA regulations. The most cost-effective and environmentally sound options for metal finishing wastewater treatment are multiple counterflowing immersion rinse tanks, reactive rinsing, spray rinsing, and combination rinses.
Metal finishing operations have an in-house treatment system so that acids, alkali, oils, and dissolved metals are economically disposed of and sent to sewers since the water becomes unsuitable for use again. However, reverse osmosis, a relatively simple and low-maintenance system, can help recover at least half of the water and make it safe for use.
Ventilation systems remove dangerous fumes from process tanks. The highest cost involved with ventilation is the electricity used for the operation. The secondary cost depends on the location and the reconditioning (heating or cooling). Some industries utilize automatic tank covers and fan controls, which can reduce the fumes, thus resulting in lower costs.
Acid Cleaners and Acid Etches
Acids used in metal plating are cleaned via acid baths. If the acid bath does not have effective process controls, it can lead to defective metal plating and finishing over time because of inconsistencies in the acid strength level. An ineffectively managed acid tank can become useless and will have to be disposed of, resulting in costs to replace the tank and the acid cleaners. To extend the life of the acid bath and reduce costs, any dissolved metal content should be removed through metal dissolving methods such as diffusion dialysis and acid sorption.
During metal finishing wastewater treatment, alkaline cleaning tanks clean a large amount of dirt, oils, grease, wax, polishing compound, and light oxides at the beginning of the process. It is important to keep track of the cleaning strength of the alkaline cleaners to reduce costs and the environmental footprint.
Metal Finishing Wastewater Treatment
The metal finishing process produces wastewater that must be treated to separate the dissolved metals in the wastewater from the liquids following chemical treatment and precipitation. A filter press with polypropylene filter plates and cloths is typically used, as polypropylene is resistant to the corrosive nature of this type of waste stream. Gasketed filter plates and cloths (versus non-gasketed) are also well suited for a corrosive slurry, as there is less chance of leakage.
After the metal finishing wastewater has been processed via pressure filtration, the resulting filter cake is then discharged from the filter press. The filter cake can then be further dehydrated using a continuous sludge dryer. For example, the M.W. Watermark continuous sludge dryer can reduce the waste volume and weight significantly, offering an average yearly savings in disposal costs of up to 60%.
Not only can changing up a business’s wastewater cleaning processes reduce overall costs, but it can also help the industry remain competitive and environmentally sound.
Contact M.W. Watermark to learn more about saving money in metal finishing wastewater treatment while preserving the environment.
About M.W. Watermark
M.W. WATERMARK wants to make a difference. We are passionate about the world’s water. We are innovative, focused on customer service and always try to exceed expectations. We are an environmentally conscious company with people who are energized, encouraged and inspired to make a difference on our planet by helping to keep our shared, finite water supply clean and usable for generations to come. We build amazing, custom water and wastewater treatment equipment. Together, we can make a difference.
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