Ozone Application for the Improvement of UASB Reactor Effluent. II. Toxicity Evaluation

Abstract

In order to improve the effluent from domestic sewage treatment through an anaerobic process in an upflow anaerobic sludge blanket reactor (UASB), CETESB - The Environmental Protection Agency for Sao Paulo State, and FILSAN - Equipamentos e Sistemas S/A, developed a joint program to study the effectiveness of ozonation of the effluent as a post-treatment process. As the effluents treated by this system could contain toxic chemicals, Daphnia similis toxicity tests were applied. Two ozonation conditions were evaluated: (1) contact time of 30 min, mean ozone application dosage of 15.9 mg/L; (2) contact time of 50 min, mean ozone application of 16.7 mg/L. Toxicity reduction occurred for all samples but one. The ozonation system eliminated the residual toxicity associated with the effluent treated by the UASB reactor.

Keywords:

• Ozone
• Municipal Wastewater Treatment
• Upflow Anaerobic Sludge Blanket Reactor
• Toxicity Reduction