Anaerobic treatability of selected organic toxicants in petrochemical wastes

The objective of this research was to study the biodegradability of ethylene glycol, acrylic acid, acrolein and allyl alcohol using a methanogenic acetate enrichment culture. Anaerobic Toxicity Assays (ATA) and Biochemical Methane Potential (BMP) studies were performed with serum bottles. Ethylene glycol was found to be degraded to less than 5 mg/l with spikes up to 10,000 mg/l. Higher concentrations led to pH inhibition even with a design initial bicarbonate alkalinity of 6000 mg/l as CaCO₃. Acrylic acid was degraded with almost no effect on methanogens with spikes up to 100 mg/l. However, concentrations of 500, 1000 and 1500 mg/l were found to inhibit the methanogens for several days before recovery. Acrylic acid was eventually degraded to less than 1 mg/l in all cases. Acrolein was inhibitory at concentrations as low as 10 mg/l. However, recovery of the culture was observed at concentrations up to 150 mg/l. Allyl alcohol was cometabolized when acetate was supplied to the bottles in the ATA; it was not degraded well when supplied as the sole carbon source in the BMP study. Ethylene glycol and acrylic acid were found to be suitable for anaerobic treatment whereas allyl alcohol and acrolein were not suitable at the selected concentrations using a methanogenic culture.