If you have a grease trap/interceptor, maintain it properly. Work out a specific cleaning schedule right for your restaurant. All GRD's need to have the separated FOG cleaned out periodically. Frequent cleaning can eliminate smells associated with a poorly maintained GRD. Chemicals and extremely hot water only push the problem further down the sewer. It does not go away. You can hire a Waste Hauler, or plumber to maintain your GRD and handle the required paper work for the control authority. Stop FOG at the source to prevent overflows and additional cost.