My septic system periodically gets clogged with hardened grease build up which I have to manually clean out (about twice a year). I use a bacteria additive monthly and have the tank pumped bi-annually. The system is very old, but I don't believe the problem is anything other than this grease build up. I am wondering if grease traps are sold/installed in homes as they are in Restaurants and if that would help. Is there a non-commercial sized grease trap?
Don't dump grease down the drain. Discard it in the trash (or use it for further cooking.) Pour out grease/oil into a can for cooling, possible refrigeration and re-use, or to discard in trash. Wipe most remaining grease out of pots and pans on a paper towel and discard it, before washing.
Also, go with the recommendations of virtually every public health department and cooperative extension and stop wasting money on "bacteria additive" - none do any better than the ones in the waste stream naturally, and some have deleterious effects (they successfully "liquify wastes" and plug your drain field, when the whole point of the septic tank is to separate those solids so they can be pumped out.) A plugged drainfield is VERY expensive (you need a new drain field.)
You can install a small grease trap inside, but then you need to maintain it. Or you could install a large grease trap (pretty much like another septic tank) outside, ...but then you need to maintain it (in some places, there is a minimum pump schedule by law for grease traps.) Grease trap maintenance is decidedly gross - it smells terrible.
I have a similar issue, but I do believe it may be due the fact that heavy duty detergent "creams" are used to cut heavy grease and fats from cooking vessels. The emulsion created then subsequently separates in the cooler ambient of the drain pipes resulting in adhesion to the PVC pipe walls causing periodic blockage.
Planning to design and install a serviceable 5 gallon bucket grease trap just outside the kitchen.