Stripping System Rinse Water Handling Requirements
Our entire stripping proess is designed for staff and customer's item safety and proper stripping. This requires that we give attention to neutralizing the rinse water used. Most shops don't even understand the enviornmental implications of their waste water.
The process of using methylene chloride chemicals for the stripping of finish from furniture items for eventual refinishing generates a potential hazardous waste, if not handled correctly. Just like having a correct process to utilize for the handling of methylene chloride chemicals for the finish removal and the eventual processing and disposal of the chemicals, there must also be a process for the water used to rinse the stripped item.
The rinse booth or other rinse area should reasonably confine the water usage and spray to within a limited area. An appropriate exhaust fan should remove the water mist away from the operator. The air flow requirements are much like those for a spray booth for finishing. The target booth design is 100-125 fpm at the face of the booth. Our booth accomplishes the flow rate by using sneeze curtains to reduce the area of in-flow. The stripped and rinsed furniture item should be removed to a properly enclosed drying area that also confines and exhausts the drying vapors.
The question becomes how to properly handle the contaminated rinse water. The dirty water still contains some residues of the removed finish and certainly some of the methylene chloride chemicals. A goal should be to remove as much of the stripper while still in the strip tray by various means, to include using a squeegee.
You can NOT dispose of contaminated rinse water into:
- the ground, PERIOD.
- the storm drain system, PERIOD.
- the sanitary sewer system, without a proper permit from your sanitary sewer district.
The sewer district will likely be unfamiliar with such a permit requirement. Ours had to be helped along by the state environmental officials.
The pump sends this filtered but still dirty water over to a holding tank located behind the rinse booth.
The holding tank has a capacity of 300 gallons. Based on its total capacity we have created a dip stick that tells us about how many gallons it is holding. The tank is capped with a hinged exterior mdf cover to control for the off-gassing that will occur.
The bottom of the tank has a 12’ long loop of ½ copper tubing with hundresds of small holes drilled into it. It is fed by an air line with a control valve for quantity of air needed. Since our rinse pump is a high pressure but low volume pump, we can normally strip 2 to 3 times before the farm tank gets ¾ full. When that point arrives we pump air into the copper tubing and out the small holes in the bottom of the tank. The goal is to reach something like a slow boil on the stove when cooking. The process is called spurging. We operate it for three 8 hour work days. The bubbling effect lifts the remaining methylene chloride chemicals to the top of the wate where they can then off-gas through a seperate vent in the holding tank lid.
The tank cover has a 5" flexible tubing that goes up to a heavy duty exhaust fan that sucks the air from the tank to outside the roof of the building.
We also use the rinse booth to further clean the floor mop and personal protective equipment used so that any residue cleaned off of our equipment is also contained.
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