How can I eliminate FOG from septic tank
The best way to control fog is to collect oil and grease in a container and sent it with garbage. Some city have programms for fog collection so you should check with your locality. If you throw oil and grease to sewage you will always have problems.
As Tamie says don't put any oil or fat down the sink, if however you have a commercial kitchen then it is impossible to keep all FOG out of the wastewater (a 10000gal tank suggests that you may be commercial) then you will need to install a grease trap (separate tank with the t baffles extended to at least half depth and sized on the daily flow). This is installed before the septic tank so that the FOG has time to solidify and float before entering the septic tank.
If you have commercial dishwashers then you will probably require a larger FOG tank as they discharge very hot water and it needs more retention time to cool. A septic planner in your area will be able to determine flow rates and size the FOG trap accordingly.