Tank Venting: How to reduce Trihalomethanes (THM) from drinking water

Area of Expertise = Active Tank Headspace Ventilation

Active tank headspace ventilation is the practice of adding a powered blower system to your tank. There are two reasons to consider this treatment approach:

To create ideal conditions for removal of any volatile gasses that are dissolved in the stored water, i.e. trihalomethanes, sulfides, methane, carbon dioxide, etc.
To decrease the average humidity and temperature of your tank headspace, reducing condensation and thereby prolonging tank coating life.

Weather stripping THMs to keep in regulatory compliance, or controlling tank headspace humidity levels to prolong your tanks operating life, our proven line of active headspace ventilation systems come with all the correct controls to ensure the operational status of the system can be remotely verified, and seamlessly integrate with your SCADA system. Our controls also come standard with a VFD so that the blower can be tuned to match the exhaust capacity of your existing tank, ensuring that our Powervent blower motors operate at the correct amperage draw.

Three Ways to Achieve Cost Effective and Efficient THM Removal

Successful tank-based trihalomethane (THMs) aeration requires three elements:

A well-mixed tank
A continual supply of fresh air circulating through the tank headspace
Enough water surface area to achieve the desired level of removal

Active mixing and ventilation are the first steps in THM removal. A PAX Mixer is used to continually move THM-concentrated water to the surface where THMs are volatilized and evacuated by the Powervent®.

Enhanced THM Mass Transfer with Surface Aeration

In situations that require higher THM removal rates, or where tank turnover requires rapid treatment, additional mass transfer (the movement of THMs in the water into the air or tank headspace) is accomplished by adding surface aerators.

These electrically powered devices float on the water surface inside the tank and create additional surface area for THMs to volatilize into the tank’s headspace.

The cost of additional horsepower is often necessitated by the regulatory need to remove large quantities of THM species.