Investigation of Thecontrol of the Fat, Oil and Grease in Sewer Lines and Their Removal By Surfactant Treatment

This study investigated different methods of controlling the fat, oil and grease (fog) in sewer systems. a comprehensivecontrol program was developed for the city of mashhad (iran) to maintain its sewer system and prevent blockages. the control program consisted of three parts: 1) fat, oil and grease source control, 2) sewer system modification,and 3) preventive maintenance. this program included guidelines for food service establishments, which are the major sources of (fog). food service establishments must implement better management practices to reduce (fog) from entering the facility drain and install grease removal devices. as a part of preventive cleaning, the performanceof several surfactants was evaluated as a cleaning agent. a 50:50 mixture (10 v. % in water) of two industrial surfactants, one containing monoethylamine and sulfonated lauryl alcohol and one containing nonylphenolethoxylate and potassium hydroxide, had the best performance and removed 80 % of the fat. response surface methodologywas used to determine the optimum conditions for the surfactant. the optimum conditions were a contacttime of 36 h, shaking rate of 30 rpm and surfactantconcentration of 12.5%. the second part of the program consisted of removingdead zones and increasing wastewater velocity in the sewer lines to enhance the hydrauliccondition of the sewersystem and decrease fat deposition. finally, a detailed and well-definedcontrol program could solve fog problems in sewer systems.