Reza Shokoohi
Hossein Movahedian
Abdollah Dargah

Phenol is a toxic hydrocarbon that has been found in the wastewater of several industries, including the petroleum and petrochemical industries. The discharge of untreated wastewater from these industries causes environmental pollution, especially in water. The aim of this study was to evaluate the efficiency of phenol removal from wastewater using a biofiltration system. In this experimental study, a cylindrical plexiglass biofilter reactor with an effective volume of ۱۲ liters was used. A total of ۳۰ pcs of plastic grid discs were placed inside the reactor by plastic pipes to maintain the biofilm media in the reactor. The microorganisms used in this study were obtained from the biological sludge of a municipal wastewater treatment plant. The reproduction and adaptation of the microorganisms to ۵۰۰ mg/L of phenol lasted three months. The effects of pH, phenol, nitrogen, phosphorus, glucose concentration, and hydraulic retention time on the biofilter system’s performance was evaluated. The results of this study showed that in optimal conditions, this system can reduce the phenol concentration from ۵۰۰ mg/L to zero within about ۴ hr. Maximum efficiency occurred in pH = ۷, and the proper COD/N/P ratio was ۱۰۰/۱۰/۲, respectively. In general, this biofilter system is capable of removing ۵۰۰ mg/L of phenol concentrations and an organic load of ۴ - ۴.۵ kg COD/m۳ .d within ۴ - ۵ hr. with high efficiency