A Survey on the Removal Efficiency of Fat, Oil and Grease in Shiraz Municipal Wastewater Treatment Plant

Abstract

Background:Fat, oil and grease (FOG) in municipal wastewater treatment plant (MWWTP) caused many problems. Objectives: This study aimed to determine the removal efficiency of FOG in Shiraz MWWTP. Materials and Methods: The removal efficiencies of FOG in the MWWTP were studied from June 2011 to September 2011 in Shiraz (Iran). The influent and effluent wastewater samples were collected in a volume of one liter (4 samples per week) and analyzed according to the standard methods. Samples are transferred to the laboratory immediately. The concentration of FOG was determined using the solvent extraction and separating funnel and then compared with the effluent standards. To analyze the data, SPSS (version 11.5), Chi-square test and t test were used. Results: The results showed that the FOG amount in input raw sewage in the MWWTP from June 2011 to September 2011 was around 25.5 mg/L and the amount in treated wastewater was about 8.1 mg/L. The FOG removal efficiency in this refinery was about 70% and met the environmental standards for the discharge (less than 10 mg/L) (P < 0.05). Conclusions: The effluent can be discharged to surface waters or used for irrigation. In order to the FOG concentration met the effluent standards, it is very crucial to control the entrance of industrial wastewater to the municipal wastewater collection networks. Otherwise, the MWWTP should be upgraded and the special techniques used to reduce FOG.