S. Chaiyanan, I. Niyomtoon, W. Porntaveewat, N. Sooksai, and S. Chaiyanan, “EFFLUENT MANAGEMENT OF PALM OIL FACTORY WITH OZONE TREATMENT BEFORE BIOGAS PRODUCTION”, PRRJ(Sci&Tech), vol. 16, no. 2, pp. 45–56, Nov. 2021.