Tiede’s 4 Recipes for Wastewater Success
Part 2: Know Your System Layout
Welcome to our four-part monthly series where Robin Tiede, Aquapure Product Manager, provides recommendations and tools that can help shorten the time it takes to solve any upsets in your wastewater system.
Last month Robin explained why data is so important, but in continuing to understand the changes that cause upsets in your industrial wastewater system it is important to understand the system layout and what happens in each tank.
Wastewater System Review:
The various streams flow into the equalizing tank where they are co-mingled after any pretreatment for reduction of hexavalent chrome and cyanide. These streams will even out the pH and then react with each other.
The wastewater then flows to the next tank where a coagulant is added and the pH is adjusted for optimum treatment of contaminants in the waste. If chelators are present they can be treated by the addition of special coagulants. Chelator containing streams should be segregated from metal bearing streams to minimize the impact of tying up the metals in the equalizing tank. The effect of chelators can also be overcome in many cases by the addition of metal precipitants. For maximum effectiveness they should be added on the alkaline side at a low dose.
Metal precipitants are always controlled by ORP (oxidation/ reduction potential) to insure the reaction can be monitored without adding excessive chemistry. Once a negative drop, measured in mV (millivolts), on the ORP is reached and stabilized, the wastewater particles are massed together in the flocculant mixer tank. This is achieved through slow movement with the addition of a flocculant polymer.
Once the particles have massed together in aggregates they are fed to the clarifier where the particles roll down the inclined plates to the bottom where they are then sent to a thickening tank to be further condensed before pressing out in the filter press.