Question: We use several adhesives and sealants in our plant, and dissolve or emulsify residues in our process water during cleaning operations. Can we safely dispose of this water into the drains?
Answer: I suspect that the concentration of your products in the water is very low, but the answer is almost certainly no. First, you have to distinguish between water that is disposed into the drains with your storm water (which means that it flows directly into streams and rivers) and the wastewater that goes to a municipal water treatment plant. Many adhesives and sealants are biodegradable, which is good for the environment. However, it means that they increase the biological oxygen demand (BOD) of the water; thus, the water needs to be treated.
BODs are normally five-day values measured in a laboratory and are designed to simulate what happens in a biological sewage plant. BOD levels from industrial plants are not mandated by the U.S. Environmental Protection Agency (EPA) but will be set by your local municipal treatment plant. Typically, if your waste exceeds a BOD value of 300-400 mg/l, they will charge you extra fees, although most plants can actually handle 1,000mg /l or more.
It’s essential that you get a water laboratory to measure the BOD of your entire waste measured, because dilution with ordinary sanitary waste will usually lower the BOD level substantially. In some cases, you may contaminate the water with other impurities, such as heavy metals; in this case, you will need to get that water measured as well.
Any views or opinions expressed in this column are those of the author and do not represent those of ASI, its staff, Editorial Advisory Board or BNP Media.