Evaluation of Horseradish Peroxidase for the Treatment of Estrogenic Alkylphenols

The xenoestrogen alkylphenols 4-nonylphenol (3.4 mg/L) and octylphenol (6.0 mg/L) were oxidized by hydrogen peroxide using horseradish peroxidase (HRP) as a biocatalyst. Substrate transformation required about one mole of peroxide per mole of phenolic compound. A high degree of conversion of alkylphenol was achieved within a 3-h reaction time. In the case of 4-nonylphenol, HRP treatment led to complete disappearance of Microtox toxicity. Results of the yeast estrogen screen (YES) assay demonstrated that the reaction products of HRP-catalyzed 4-nonylphenol conversion lacked estrogenic activity. A new approach to the YES assay has been suggested based on observations made during this study.

Biodegradability of Orimulsion in Saltwater and Freshwater Environments1

ABSTRACT Shake flask and respirometer experiments were executed to test the biodegradability of Orimulsion in freshwater and saltwater. For each experimental setup, two concentrations of the Orimulsion and the appropriate bacterial inoculum were added to artificial seawater and freshwater solutions, and the concentrations of Orimulsion hydrocarbons were monitored with time. Respirometers were used to monitor oxygen (O2) uptake and carbon dioxide (CO2) evolution to determine when to sample the shake flasks. Sampling of shake flasks occurred periodically by sacrificing triplicate flasks for each treatment. Residual hydrocarbons were extracted with dichloromethane and quantified by gas chromatography/mass spectrometry (GC/MS). The respirometry flasks were sacrificed on the last shake-flask sampling event and similarly evaluated for residual hydrocarbon content and for Microtox toxicity. Data reported confirm literature citations that Orimulsion is indeed biodegradable, at least to some extent. In the 10 g/L freshwater treatment, normal and branched alkanes present were degraded by 83.6% and PAHs by 59.8% after 183 days of incubation. In saltwater, the extent of alkane and PAH degradation was 93.5% and 81.4% after 183 days. Implications for cleanup are discussed.

Removal of Oxygen Demand and Acute Toxicity during Batch Biological Treatment of a Petroleum Refinery Effluent

A survey of the process streams at an operating petroleum refinery showed that desalting water from the crude and splitter units had the highest concentrations of pollutants, and accounted for approximately one-third of the BOD and COD of the combined effluent. Combined effluent (234 ± 62 mg BOD/L, 510 ± 0 mg COD/L, and Microtox EC50 4.9 ± 0.4%) was treated using a laboratory-scale batch biological reactor. Ninety-three percent of BOD and 77% of COD were removed over the first 24 hours of biological treatment. Acute (Microtox) toxicity was reduced in two discrete stages; the first coinciding with BOD and COD removal and the second stage occurring after BOD and COD had been removed. A final EC50 value of 27.8% was achieved in batch tests. The two stages of toxicity removal correspond quantitatively to the toxicity removal observed during secondary and tertiary biological treatment at the petroleum refinery's full-scale wastewater treatment plant.