Some use a system that injects chlorine and then sends the water into a contact tank to let the chlorine do its thing. That is followed by an activated charcoal filter tank that removes chlorine and things that can be filtered such as iron and I think sulfur once the chlorine has done its thing. This activated charcoal filter regenerates like a water softener periodically in the middle of the night.
I use a catalytic carbon (Centaur Carbon) filter for iron and sulfur. It depends on the water having some dissolved oxygen. It also regenerates. It does use a 15 gallon solution tank that I fill every 5 weeks with 1.5 gallons of bleach and top up with water. That bleach solution is only used for the regeneration cycle, which is every 3 days.
Another thing you could do to make cleaning more effective is to replace the faucet on the side of the water heater with a 3/4 inch NPT nipple and full port ball valve (or even temporarily with just a long nipple). That gives you a 3/4 inch port for cleaning. If you remove the anode at the top (takes a 1-1/16 inch impact socket on an impact wrench, at least for the first time) for another port. Together this might make cleaning more effective. It seems to me that if you drained a water heater into a tub, you could use a sump pump intermittently to spray water into the top of the water heater to pick up precipitate and wash it out the side. The tub would be dumped when it had accumulated dirty water, and clean water would be added to the procedure by turning on the valve supplying the water heater. The bigger valve port would make the draining quicker and increase the particle-carrying capacity of the flow.
An alternative would be to drain the water right to the septic with gravity and intermittently turn on the supply to the water heater. The water would come in the dip tube, and hopefully develop enough turbulence in the empty tank to carry out more precipitate. That would spray water at a fixed spot. Spraying a hose nozzle into the anode hole would let you move the stream of water around.
Just ideas.