Phenol- and thiocyanate-based wastewater treatment in RBC reactor

A laboratory-scale investigation at ambient temperature was performed to examine the applicability of a four-stage across-the-flow rotating biological contactor (RBC) reactor for the treatment of synthetic wastewater containing phenol and thiocyanate. The composition was so maintained that the phenol to thiocyanate ratio approximated that usually found in coal carbonization effluent. In the combined treatment of the toxicants, it was noted that the toxicants were removed in sequence. Phenol was mostly removed in the earlier (first and second) stages, while thiocyanate-fed microbes acted more efficiently in the latter stages (third and fourth). The overall reaction rate coefficient for phenol biodegradation (K-PH) varied in the range of 10.20-3.50 g/m(2) . d in presence of 0-240 g/m(3) of influent thiocyanate concentration. The same coefficient for thiocyanate biodegradation (K-TH) was found to be in the range of 8.20-0.30 g/m(2) . d in presence of 0-240 g/m(3) of influent phenol concentration. The effects of various operating and process parameters such as disk rotational speed, temperature of the reactor liquid, and substrate load on the removal of phenol and thiocyanate were also examined. The microbes, predominantly found in the earlier stages, were identified as Pseudomonas putida, Pseudomonas stutzeri and Candida tropicalis, whereas in the latter stages, Thiobacillus thioparus and Nocardia sp. populations predominated.