Hydrogen Peroxide Turn-key Program Helps Refinery through Aeration Basin Maintenance Outage
[vc_row][vc_column][vc_column_text]US Peroxide’s 27% Hydrogen Peroxide Treatment Program offered the refinery several benefits:
US Peroxide’s turnkey supply scope provided a safe and cost effective solution for supply of supplemental dissolved oxygen to this large refinery during the maintenance outage.
The biological treatment system’s performance during the outage convinced the refinery to maintain the hydrogen peroxide storage and dosing system on site to provide supplemental dissolved oxygen (DO) on as “as needed” basis during periods of high BOD/COD loading, upstream process upsets, and filamentous bulking episodes.
In the summer of 2010, a large refinery complex in the Northeast was a facing a 2-3 month maintenance outage on one of two aeration basins in their activated sludge wastewater treatment system. During the outage, all of the refinery wastewater would need to be routed through the one remaining aeration basin. Since the refinery periodically had difficulty maintaining dissolved oxygen (DO) levels with both aeration basins in service, they needed a temporary (and non-capital) means to provide the biological treatment system with supplemental DO during the maintenance outage.
Hydrogen peroxide has been used as a source of supplemental dissolved oxygen (DO) in activated sludge treatment systems for decades. In the aeration basin mixed liquor, H2O2 converts to DO according to the following reaction:
2 H2O2 → O2 + 2 H2O
This decomposition to DO occurs very rapidly due to the catalytic effect of enzymes (i.e. catalase) present in all activated sludge mixed liquors, and thus provides an immediate source of DO to the biomass. Since hydrogen peroxide is a liquid, and infinitely soluble in water, the amount of DO provided is not limited by mass transfer of oxygen from the gas phase to the liquid as is the case with mechanical aeration. More information on this application is provided at this link: Supplemental Dissolved Oxygen.
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Re-Refinery Used Oil | Sour Water Treated with Hydrogen Peroxide
[vc_row][vc_column][vc_column_text]In North America, approximately 1 billion gallons of used oil are collected annually from generators such as quick lubes, truck fleets, and manufacturers. Several companies have begun the process of re-refining this hydrocarbon-rich waste product. Re-refining allows the lubricating oil to be repeatedly re-used as a higher value product.
Re-refining involves operations which will separate and remove contaminants in the used oil so that this oil becomes suitable for reuse. The re-refining process is much like that of a traditional refinery with similar waste treatment requirements. Such was the case for a major used oil re-refinery facility in the mid-west. They had a “sour water” treatment system that was not performing as designed, resulting in operational problems and safety concerns. Sour water is hydrogen sulfide rich wastewater water that is generated from a variety of sources including hydrotreaters, reformers and hydrocrackers.
Hydrogen peroxide has been shown to be a convenient, cost effective and environmentally friendly part of hydrogen sulfide gas scrubbing technologies. Scrubbing of hydrogen sulfide using sodium hydroxide and hydrogen peroxide is a well-established technology.
A typical scrubbing solution consists of dilute sodium hydroxide to which enough hydrogen peroxide is added to react with the hydrogen sulfide according to the equation:
4H2O2 + H2S → H2SO4 + 4H2O
The above reaction predominates at pH > 9.2, and yields soluble sulfate as the reaction product. The stoichiometry calls for 4.25 lbs H2O2 per lb S 2– and it is not unusual for reaction efficiencies to approach 100%, provided that the hydrogen peroxide is added in a controlled fashion and the reaction medium is thoroughly mixed.
Enough sodium hydroxide must be present to neutralize the sulfuric acid formed according to the equation:
2NaOH + H2SO4→ Na2SO4 + 2H2O
This indicates that for each weight part of hydrogen sulfide, approximately 2½ weight parts of sodium hydroxide are needed.
USP Technologies provides a full scope of supply (chemicals, equipment and services) to support emergency and ongoing applications for hydrogen peroxide and a range of water and wastewater treatment chemicals.[/vc_column_text][/vc_column][/vc_row]
Advanced Oxidation for High Strength Caustic Wastewater
A refinery in the Northeast was looking at options to dispose of 10,000 bbls of a high strength, high pH caustic wastewater that had been stored in one of its tanks. The wastewater had very high phenol levels (14,000 mg/L), which did not allow for processing through the activated sludge system due to biological toxicity issues.
Off-site hazardous waste treatment options were available, but would have cost over $600,000. A less expensive, temporary, non-capital and on-site treatment approach that would eliminate the phenols and allow for processing through the activated sludge system was evaluated and implemented at this facility.
Earlier in the year, the refinery had a major activated sludge system upset caused by high chemical oxygen demand (COD) loading that killed the nitrifying bacteria and lowered the dissolved oxygen (DO) levels, which made it difficult to recover and achieve required ammonia removal. USP Technologies (USP) successfully solved this problem using hydrogen peroxide for sulfide oxidation and supplemental DO, which helped the activated sludge system recover and created an environment that allowed the nitrifying bacteria to reestablish. Having successfully solved this problem, USP was asked to look at the high strength, high pH caustic water in order to determine if it could be treated on-site and processed through the activated sludge system in a safe and economic manner.
A Gulf Coast Refinery was using hydrogen peroxide (H2O2) in 55-gallon drums at their WWTU Bio Unit to supply supplemental dissolved oxygen (D.O.) to maintain target D.O. levels in the aeration basins during high COD loading periods. The drums were stored on wood pallets, which violated industry safety standards and also required handling (changing out the drums), which increased the risk of spills and exposure to operators. Furthermore, during a turnaround of an upstream unit, higher COD loading depleted the dissolved oxygen level in the WWTU Aeration Basins, resulting in ineffective treatment.
The refinery approached USP Technologies (USP) to engineer a bulk H2O2 chemical dosing system sized to meet the plant’s D.O. demand. USP responded to the refinery’s immediate need by quickly mobilizing a four-person Project Team that included a local account manager and experts in the areas of technical applications, equipment system design and equipment installation/maintenance.
The team installed a USP Rapid Response System consisting of a 5,000-gallon temporary storage trailer and a modular dosing control system. Upon the addition of Refinery Grade 27% H2O2, a class 1 oxidizer, to influent of the WWTU Bioreactor System, the D.O. target was maintained during the high COD loading period.
Once the temporary system was commissioned, the USP Project Team turned their attention to providing a permanent full service chemical storage and dosing system including a 5,000-gallon double-wall HDPE tank, dual pump dosing module, chemical, field service and monitoring system.
USP worked with the plant’s engineers to determine the optimum dose point as well as the proper location for the chemical storage tank. The changeover occurred following the plant turnaround and was completed by the USP Field Services Team without incident and without disruption to the treatment program.