Chlorine Contact

Overview

Chlorination is one of the most common methods of disinfection for wastewater discharges. Contact time and mixing must be provided for chlorine to kill the bacteria in the wastewater stream. The contact time will differ based on the potential for the contact reactor to short circuit. Many codes will allow a design of 30 minutes retention only if a contact chamber is provided with a 20:1 length to width ratio for proper contact time. If the residual chlorine may itself pollute, then dechlorination may be required. This takes the same feed unit but different tablets. The dechlorination process is nearly instantaneous, so no contact time is needed. However, it does rob the water of free oxygen, so reaeration may then be required if discharging into a live aquatic environment.

Reactor Design

The American Manufacturing Company Chlorine contact chamber provides both a 20:1 ratio and 30 minute contact time for residential gravity flows. The Chlorine Contact Chamber is designed with an up and down flow pattern using three modules in series to achieve an average 20:1 length to width ratio. The water will flow down the 4″ diameter drop pipe and then rise in the 13″ wide (average) box. The resulting turbulence will enhance mixing. In conventional chambers, the length to width ratio is based on rectangular shapes. The drop pipe is circular, plus being in the center of the box will decrease the flow path between the pipe and the side wall, resulting in a better-than-conventional configuration.

Chlorinator & Dechlorinator

The Model LF-2000 has a 4 1/2″ diameter inlet and outlet. It is designed to handle the flow of treated effluent for design flows up to 1500 gallons per day. The Tablet Chlorinator has no moving or electrical parts. It uses Disinfecting Tablets – not powders or gases. The Chlorinator works by gravity flow alone – chlorine dosage automatically adjusts with increases and decreases in effluent flow. This same unit works as a Dechlorinator.

Reaeration

This reaeration module provides a 25-gallon reservoir for influent water to mix with and reaerate with air induction from a fish tank aerator readily replaceable from most local fish stores. Dechlorination will remove free oxygen from the effluent, and this device will reaerate for residential applications.