How to Treat Chelated Metals in Wastewater

Part of the water treatment process can be environmenally dangerous if left untreated.

Not every water treatment plant is meant to tackle sewer water. Some of them are part of metal-producing factories that produce wastewater considered dangerous to the environment as-is. One step in the treatment of wastewater full of metals is stabilizing them by chelation. Afterward, these new chemical structures need to be removed -- which can produce further treatment needs.

Things You'll Need

• Chelated wastewater in tank
• Treatment chemical of choice (DTC, ferrous sulfate, sodium sulfide, polyelectrolyte, sodium borohydride, or ferrous dithionite)

Instructions

1. Collect the pH-leveled wastewater into its tank during the treatment process. Once full, shut off the drainage system to prevent backflow.

2. Choose the treatment chemical to use according to your specific budget and needs. Add the treatment chemical to the wastewater, for example: polyelectrolytes. Though very expensive, the polymers will remove the chelated metals without producing an overabundance of sludge to process. DTC is commonly used, but has its own drawbacks.

3. Begin occasionally stirring the treated wastewater according to the chemical treatment maker's instructions. Though the metals will settle into sludge at the bottom, occasionally stirring the water will aid in the chemical processes involved in removing the metals as much as possible. Continue this action for at least 24 hours.

4. Separate the water from the sludge. Drain the water to its next stage in the water treatment process. Drain the sludge to its separate treatment process (such as dewatering).

Tips & Warnings

• Check the local, state and federal EPA guidelines on what constitutes safe water for businesses and the environment. The treatment of chelated metals in water is part of the water treatment process for factories. When in doubt, read their guidelines and rules set forth to find a detailed process.

• Never handle wastewater without protection. This includes masks. Some chemical treatments are poisonous to breathe in or can create poisonous fumes as part of their breakdown processes. Some of the gases may be explosive. Research your intended chemical beforehand and know the risks.

References

• SPER Chemical Corporation: The Chemistry of the Chelation Effect
• EPA; Printed Wiring Board Cleaner Technologies Substitutes Assessment: Making Holes Conductive - Ch. 6-2; Lori E. Kincaid et al.; August 1998