Simple, Safe Solution to In-line Dechlorination

By Brandon Burg

Ray Stevens, director of facilities and grounds with the City of Council Bluffs, Iowa, needed to dechlorinate wash water after it was used to clean their traveling screens and before being discharged to the Missouri River. In addition to searching for suitable equipment, Stevens was concerned with finding the safest chlorine-neutralizing chemistry for his application. This search led him to Integra Chemical Company in Kent, Wash. Initial conversations focused around using Vita-D-Chlor tablets in his application but soon led to discussions of the ZDe-chlorinator in-line dechlorination unit with the Vita-D-Chlor tablets, which had not been released yet.

The Equipment

The new device from ZDe-Chlorinator, the NEMA-C, is an in-line tablet dechlorination unit. With 2.5” NPT in and out, and measuring only 7 inches in length and height, Stevens found it easy to mount in-line using 2.5” piping, valves and check valves. Stevens’s application has a flow that can be as low as 160 gpm, which is lower than the unit’s operation range, so a valve was installed after the ZDe-chlorinator unit to ensure water filled the unit properly and received the necessary tablet contact.

Another concern was in-line pressure. The unit needed to be able to withstand varying pressures, and its 6061-T6 high-strength, aircraft-grade aluminum construction met those demands.

Dechlorination tablets are preserved between flushes by installing a system drain valve in the hole taped in the bottom of the unit. Once all systems were installed and checked, a tablet extension tube was added to hold additional tablets for this ongoing demand.

The Chemistry

Setting up an in-line system puts unique demands on tablet dechlorination. Dosing is the primary concern. This set-up properly dosed the Vita-D-Chlor tablets for which it was designed at flow rates and chlorine levels within its specifications. Once testing confirms a sufficient quantity of tablet is being dissolved, the environmentally safe chemistry of Vitamin C dechlorination ensures the system can operate without direct management for every backwash without risk of minor levels of over-dechlorination.

Integra worked with Stevens to devise the system that ensured a safe and cost-efficient dechlorination of the backwash water from Council Bluffs’ routine cleanings of its traveling screens - and protected the Missouri River from possible discharges of chlorinated water.

About the Author:Brandon Burg is vice president of sales for Integra Chemical, a Vita-D-Chlor Company.

Integra Chemical is exhibiting at AWWA’s ACE16 expo in Booth 2042.