1-hydroxyanthraquinone: Activity in Paracoccus denitrificans and potential application for biomass reduction in wastewater treatment facilities

The effect of 1-hydroxyanthraquinone (OHAQ) on respiration rate and biomass production was evaluated in Paracoccus denitrificans and in mixed cultures derived from a municipal wastewater treatment facility. OHAQ addition resulted in classic "uncoupling" activity characterized by an increase in the respiration rate and decrease in the biomass production. In anaerobic batch cultures, OHAQ increased the nitrogen production rate 64.5% and decreased biomass production 30.7% in Paracoccus. In aerobic batch cultures, OHAQ increased the oxygen utilization rate 38.5% and decreased the biomass production 39.3%. OHAQ addition to a continuous Paracoccus culture resulted in an increase in the respiratory activity compared to the steady state control values. There was a 10.4% in the carbon evolution rate (CER) and a 10.8% increase in the specific oxygen utilization rate (SOUR). The growth of the organism was not adversely affected by the presence of OHAQ suggesting that the compound could increase the capacity of wastewater treatment facilities without modification to existing equipment. The addition OHAQ to mixed cultures derived from a municipal wastewater treatment facility resulted in an increase in the initial oxygen utilization rate and a reduction in the overall biomass production. The overall oxygen utilization was not adversely affected by OHAQ. In test vessels containing 300 mg/L MLSS, 10 mg/L OHAQ increased the initial oxygen consumption rate 16.9% and decreased the biomass production 10.8%.; The activity of OHAQ derivatives was related to the electronic properties and position of the substitution on the anthraquinone ring system. There was no correlation to the Log P, pKa or water solubility of the compound.; These studies demonstrate that the activity of OHAQ is the result of the "uncoupling" of aerobic and anaerobic respiration. The results indicate that OHAQ has the potential to reduce both the capital and operating costs of biological wastewater treatment systems, especially in the industrial setting, by simultaneously improving the metabolic capacity and decreasing the biomass production rates. The uncoupling activity of anthraquinones combined with the low toxicity of compounds suggests that these compounds may be used for reducing biomass production in commercial bioprocesses in addition to traditional wastewater treatment systems.