TREATMENT OF PHENOL-FORMALDEHYDE RESIN WASTEWATERS
USING ROTATING BIOLOGICAL CONTACTORS
Chang-Wu Huang, Associate Professor
Department of Environmental Engineering
Wuhan Institute of Urban Construction Engineering
Wuhan, China
Yung-Tse Hung, Professor
Yong-Sheng Dong, Research Associate
Department of Civil Engineering
Cleveland State University
Cleveland, Ohio 44115
INTRODUCTION
The wastewaters generated from the Wuhan Chemical Plant, Wuhan, China, contained phenol
and inorganic salts from the distillation process, and filtering cloth washing in the phenol plant and
phenol, formaldehyde, methanol, and benzene from the phenol-formaldehyde resin plant. The flowchart for the manufacturing of phenol-formaldehyde resin is shown in Figure 1. Phenol reacts with
formaldehyde in the presence of hydrochloric acid as catalyst, undergoes condensation and polymerization to form the final product, the thermosetting resins. Wastewaters produced from these
various processes are called the phenol-formaldehyde wastewaters.
The wastewaters contained various toxic organics and inorganic salts, which included 30,000 to
40,000 mg/l phenol, 20,000 to 30,000 mg/l formaldehyde, and 10,000 mg/l inorganic salts of sodium
sulfate, sodium sulfite and other salts. The wastewater flow averaged 40 mVday. Recovery of various
organics and inorganic salts was practiced to recover valuable chemicals and to reduce pollution loadings prior to the wastewater treatment. Although biological treatment of phenol containing wastewaters had been reported in the literature [1,2], information on the treatment of phenol-
formaldehyde wastewaters is very limited at the present time. The objective of this study was to
determine the feasibility of using the rotating biological contactor (RBC) process in treating phenol-
formaldehyde resin wastewaters, and to determine factors affecting RBC performance, including
influent phenol, formaldehyde, and chemical oxygen demand (COD) concentration, number of stages
of RBC, hydraulic detention time, water temperature, freezing condition, inorganic salt concentration, and materials for RBC disc construction. Multi-stage RBC process was selected in the 2-year
pilot plant study because of its ability in treating wastewater containing high level of toxic organics
and of high variability in organic concentration present in the wastewaters.
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Figure 1. Schematic of Manufacturing of
Phenol Formaldehyde Resins.
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