I am our facility’s environmental, health and safety manager. Periodically, we have very high-pH wastewaters that cause the pH within the cyanide oxidation step to be well above our desired upper limit of 11. Our operator has requested that we add sulfuric acid into the cyanide oxidation stage whenever the pH rises above 11. I am very concerned about the release of hydrogen cyanide if something goes wrong and the system accidentally drives the pH well below 7. Are there any safer acid substitutes?
Over the last several months, we have had difficulty with calibration of our pH sensors, particularly the pH adjustment sensor that controls pH in the range of 9.1– 9.5 for precipitation. Somehow the sensor still works well enough for us to achieve metal precipitation to maintain compliance, although our effluent’s metal concentrations are a little higher than in the past. We feel very uncomfortable continuing this way. Any ideas to help?
Do you know of any papers or charts that give water evaporation rates? We have an opportunity to reduce our cleaner tank temperature from 180 to 80°F and want to know how much water we can save.
What is the best way to treat this rinse water to reclaim the palladium? I’ve heard reclaiming palladium can be costly. Is it even worthwhile to treat this rinse water?
My question is this: Do we still need to run this incinerator since we aren’t producing anything that would harm the environment, or can we at least turn the temperature down? We currently run it at 1200°F. I have asked, but nobody seems to know.
Now our wastewater treatment operator pays much more attention to the firmness quality of the sludge, and we send out a sludge sample for total solids analysis on a monthly basis. Over the last several years, our annual sludge analysis for TCLP chromium has given results within historical norms.
We are considering switching to magnesium hydroxide since jar tests performed by a chemical supplier indicate a 30% reduction in filter press cake at a pH of 8.5. Our flow consists of 2/3 tumbling and 1/3 nickel-chrome plating with a combined flow of 60 gal/min. Is this realistic?
One company said since our waste stream had a lead concentration of 40 mg/liter and this is over the TCLP threshold of five mg/liter, it is a RCRA-hazardous waste and gave us a quote from transportation and disposal as such. The other company claimed they can handle it as a non-hazardous waste since the waste stream’s concentration is less than 19 times the TCLP threshold of five mg/liter. Obviously, disposal as a hazardous waste is much more expensive than non-hazardous waste. Can you help us decide which way to go?
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