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Case Study

Biological Treatment of Petrochemical Waste Water

Conventional wisdom dictates that biological treatment of strong wastes must be diluted to keep the reactor COD below 5000 mg/L, and that aerobic treatment of strong wastes creates vast quantities of sludge. We developed a bioreactor that disproves both myths.

Figure 1. Fixed-Film Bioreactor

A client produced a wastewater with COD ranging from 30,000 - 60,000 mg/L. Many of the compounds in this water were difficult-to-degrade organics present at high concentrations.We developed a multi-compartment, fixed-film aerobic bioreactor that successfully treated this wastewater. The unit can be operated at ambient temperature in batch mode or continuous flow. Remarkably, our bioreactor reduced COD by 80% with an 8 hour retention time. Concentrations of recalcitrant compounds like pyridine, tetrahydrofuran (THF) and dimethylformamide (DMF) were reduced to < 20 mg/L., from initial concentrations of 450-750 mg/L (See GC traces, Figure 2). Few have attempted to biologically treat such strong wastewater, never mind attaining our success!

Ours is one of the few bioreactors designed to treat high strength wastewater biologically. This work demonstrated that with sufficient captive biomass even recalcitrant compounds can be treated, provided conditions are manipulated carefully.

Figure 2. Wastewater before (left) and after (right) treatment in our bioreactor.