Ask the Expert Question-and-Answer Archive (Wastewater Treatment)
by Mike McGinness, EcoShield Environmental Systems, Inc.
Industrial Wastewater Filtration Systems
What technologies are available for treating industrial wastewater streams that have high concentrations of disolved metals, high percent suspended solids, and significant percent of cleaners, degreasers, and soaps? Flow rates are 500,000 gpd, 400gpm peak, 0.2% TSS, 2% TDS by weight.
If it was my problem, the first thing I would do is fire the people that designed and built the system that is producing such a hard to treat waste water stream. That mix is nearly impossible to treat, and certainly not one that can be cost effectively treated or recycled. In today's world we design systems to produce designer waste water streams, so that we can recycle some of them and make the remaining ones much easier and cheaper to treat.
Electrocoagulation is one of the few treatment methods I know of that I would bother with trying, but it has serious operational (electrical energy) and maintenance (electrode replacement, time and materials) costs. That waste stream and volume would be a daunting task to tackle even for electrocoagultion!!! And electrocoagultion would require follow up steps to complete the treatment, and would produce a large amount of sludge.
The problem is this. First, I am assuming the dissolved metals you mention include one or more that are toxic to bacteria at just a few ppm (copper, silver to name a few) and I assuming that they at levels that would be toxic to bacteria, so that eliminates biological treatment of the soaps and organics. The first rule of industrial waste water treatment from metal finishing is you keep dissolved metals waste water streams separate from those with soaps and cleaners, especially those with chelating agents.
I am afraid to ask how you ended up with such a daunting waste stream to tackle?
Let me know if I can be of any further service?