Performance assessment of sulfidogenic fluidized-bed reactor for cotreating of acid mine and pharmaceutical-containing wastewater

Sulfidogenic co-treatment of real acid mine and hospital wastewater was explored in mesophilic operated fluidized-bed-reactor. The hospital wastewater that is enriched with organic matter was used as the primary source of carbon for sulfate reduction bacteria. The biotreatment was tested for its robustness since it used samples from real wastewater streams which were collected at different times, which shocked the systems. Efficiency in sulfate and chemical oxygen demand removal was more than 95% and 96%, respectively. Organic oxidation has been found to be the controlling factor in the sulfidogenic treatment of SO42- and metal-containing wastewater. The metal concentration removal was more than 99% in effluent for iron and zinc and precipitated predominantly as FeS, FeS2 and ZnS. The alkalinity generated by COD oxidation improved the pH of the wastewater considerably when the concentration of feed sulfate was less than 3500 mg/l. At an HRT 8 h, COD oxidation in the reactor precipitated 1345 mg Fe/l/day, 543 mg Al/l/day and 130-170 mg Zn/l/day from acidic wastewater and increased the pH from 2.2 to 6.8, due to formation of metal sulfide precipitate. The ANN model was successfully developed, and the predicted and actual measured concentrations of the outputs found an R value of 0.97.