Supplemental Dissolved Oxygen - Refinery

The use of hydrogen peroxide to supply supplemental dissolved oxygen (DO) to activated sludge and other biological treatment systems at oil refineries is well documented and has been successfully practiced for decades. USP Technologies (USP) is an industry leader in the safe & effective application of peroxide for this purpose and has implemented numerous programs at refineries across North America for over 20 years.

Although peroxide is applied in this way across a wide variety of industries, the specific challenges faced by oil refinery wastewater treatment systems make peroxide a particularly useful tool for refinery wastewater operators. These challenges include highly variable levels of influent COD, flow rates, ammonia/total nitrogen, to name a few. High influent temperatures also reduce the solubility of oxygen and therefore lower the mass transfer efficiency of mechanical aeration systems. Experience has shown that these variations in influent characteristics are often associated with refinery maintenance “turn arounds”, changes to the refinery crude slate, or “bleeding” spent caustic streams into the biological treatment system. These factors can overload the wastewater system aeration capacity and acceptable DO levels can’t be sustained – this is where hydrogen peroxide feed to the aeration basin influent can provide an immediate source of supplemental DO needed to handle these periodic upsets. Maintaining adequate dissolved oxygen levels in the aeration basin is critical to support effective biological COD removal & nitrification. Low mixed liquor DO levels are also associated with the excessive growth of several types of filamentous bacteria, which can result in poor settling and high effluent TSS.

In the aeration basin mixed liquor, H2O2 rapidly adds DO to the aeration basin according to the following reaction:

Catalase enzyme is a natural decomposition catalyst for hydrogen peroxide, and is found in all activated sludge mixed liquors, being produced by most aerobic organisms. Because this enzymatic decomposition of hydrogen peroxide to DO is very rapid, the oxygen supplied by hydrogen peroxide is immediately available for uptake by the aerobic microorganisms in the mixed liquor. Depending on the rate of peroxide addition, increases in aeration basin DO can be observed within a few hours of starting peroxide feed to the system. Since hydrogen peroxide is infinitely soluble in water, the above conversion of H2O2 to O2 occurs in the liquid phase, so is not limited by vapor to liquid phase mass transfer of O2 as is the case with mechanical aeration.

Once upset conditions pass and the treatment system regains normal operations, peroxide feed & associated chemical expense can be discontinued with the push of a button (or click of a mouse). Our customers enjoy the peace of mind of this dependable and easily implemented backup system.

USP’s turnkey and zero-capital supply scope includes a range of hydrogen peroxide product concentration options; state of the art storage and feed systems – including Class 1, Div. 2 (explosion proof) as required; equipment installation & maintenance services; remote system monitoring and controls; and the most experienced peroxide applications experts in the industry.