GENER-OX™

Force mains are nutrient-rich wastewater environments that can become anaerobic under conditions of low flow, where Sulfate Reducing Bacteria can convert sulfate (SO42-) to hydrogen sulfide (H2S), while simultaneously depressing the alkalinity and pH of the sewage. As the sewage pH declines, H2S volatilizes from manholes, air vents, and lift stations, leading to odor complaints. Where oxygen from air can be present, such as in the top-half of the pipe, manholes, and lift stations, the H2S will be oxidized to sulfuric acid, which condenses on surfaces, causing accelerated corrosion to concrete and steel.

Most odor control treatment approaches "shock" the anaerobic bacteria using hazardous chemicals such as peroxide, bleach, or caustic soda, or they add a sulfide precipitating chemical, such as ferric chloride, which leads to large sludge volumes. A third popular approach is to feed a nitrate (NO3-) salt, which the anaerobes preferentially select instead of sulfate. All of these approaches focus on the symptom of the problem.

IER's Gener-Ox™ chemical-free technology addresses the root cause of the problem by converting the force main from an anaerobic to an aerobic environment, using Mother Nature's oxygen to maintain aerobic conditions throughout the force main. No anaerobes → no sulfide formation. No sulfide formation → no odor or corrosion. Without the never-ending cost of chemical feed.

In a force main, the sewage experiences the pressure created by the lift pump. The higher the pressure on the liquid, the higher the concentration of any gases that can be dissolved into that liquid. Gener-Ox™ takes advantage of this science to generate and feed the maximum dissolved oxygen (DO) concentration that can be maintained based on the pressure of a given force main. In a typical installation, IER's Gener-Ox™ system draws a side-stream of sewage from a wet well, pressurizes it above that of the lift pump, and dissolves oxygen into the sewage to achieve the maximum DO saturation level for that force main. The Gener-Ox™ side-stream, now containing the very high DO level (no bubbles), is then injected into the force main on the discharge side of the lift pump, taking advantage of the force main pressure to maintain the O2 in a dissolved state and the sewer line in an aerobic environment. Again, no bubbles. A small fraction of the Gener-Ox™ side-stream can also be injected into the wet well, to maintain aerobic conditions in that environment as well. Utilizing DO sensors in the wet well and downstream in the force main, the desired DO concentration is continuously maintained in each location. The key for Gener-Ox™ success is the ability to monitor, control, and deliver on-the-fly the necessary DO concentrations to maintain aerobic conditions in the wet well and force main sewage environments, thus changing the microbiology, to completely mitigate sewer line odor and corrosion.

As an example, a lift station pumping 1000 gpm through a 30 psi force main with an oxygen uptake rate of 0.10 mg/L/min will require a Gener-Ox™ system that will pull a side-stream from the wet well of 350 gpm at a pressure of 50 psi to create a DO level of ~160 mg/L. Injection of this side-stream into the force main will result in diluting the DO down to ~40 mg/L, which will provide a DO residual for about 6-7 hours within the force main. Assuming the force main detention time is typically 5-6 hours during low flow times of the day, then there will be a measurable DO residual in the wastewater through the entire force main.

Gener-Ox™ - cost-effective, simple, and "green" odor control solution.

READ MORE ABOUT THE GENER-OX™ SUPER OXYGENATION PROCESS

For further information, please contact: Joe Hennessy
509-885-3992  |  jhennessy@inlande.com