Heater and Control Unit Prevent Freezing in Wastewater Tanks

Chromalox catalog tli

The Challenge

Filtration membranes in two wastewater treatment tanks at an Iowa ethanol producer were susceptible to damage from freezing temperatures. Each filtration membrane is valued at $1 million; any membrane damage due to freezing could result in the need to replace the entire membrane and the loss of production. The tanks 11 deep, 8 wide and 15 long are part of a closed loop system that holds thousands of gallons of water used in ethanol production. The process is critical to production, and the water must be treated before reuse or release.  A loop system was considered to keep water flowing, but the addition of such a system would have added energy and piping costs.

The Solution

A modified Chromalox TLI L-shaped metal heater was installed in each tank, mounted on a 156 riser and 4 sludge legs. Each 480V heater unit holds two tiers of three elements and is controlled by a Chromalox 4468 Contactor Panel.  The systems maintain the water in each tank between 40° and 50° F. The company also purchased a third heater/contactor system to keep on hand as a backup unit.


  • Ensuring stability of critical and expensive filtration membrane components
  • Turn-key system assures facility remains online and maintains production
  • Energy savings over alternative solution