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.

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