Determining the ecological viability of constructed wetlands for the treatment of oil sands wastewater
- Simon Fraser Univ., Burnaby, British Columbia (Canada)
- EVS Environment Consultants, North Vancouver, British Columbia (Canada)
To determine the conditions for optimal degradation of naphthenic acids (C{sub n}H{sub 2n+z}O{sub 2}), the most toxic component of oil sands wastewater, the authors have monitored the mineralization of 2 representative naphthenic acids (NA), U-{sup 14}C-palmitic acid (linear, Z = 0) and 8-{sup 14}C-decahydro-2-naphthoic acid (bicyclic, Z = {minus}4) under varying conditions of temperature, phosphate and oxygen. The radiolabeled NA was added to biometer flasks containing wastewater {+-} amendments and evolved {sup 14}C-CO{sub 2} was trapped in a side arm and counted by LSC. The results indicate that low temperature (5 C) and anaerobiasis greatly inhibited NA degradation over the four week incubation period. Addition of phosphate (as buffered KP{sub i}) significantly increased {sup 14}C-CO{sub 2} production for both Z = 0 and Z = {minus}4 compounds; however, the subsequent high microbial growth rates also decreased PO{sub 2} which limited NA mineralization. Effluent toxicity was monitored at week 0 and week 4 using Microtox and fathead minnow tests. Although there was increased survival of fathead minnows in the phosphate-amended effluent, the IC{sub 20} values of the Microtox assay showed no improvement in either the phosphate-treated or untreated effluents. These results show that naphthenic acid analogues are readily degraded by indigenous microorganisms in oil sands wastewater and that phosphate addition accelerated the mineralization of these compounds if PO{sub 2} remained high.
- OSTI ID:
- 242336
- Report Number(s):
- CONF-9511137--; ISBN 1-880611-03-1
- Country of Publication:
- United States
- Language:
- English
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