For all those who are skeptics of going organic. I had a lawn in VA and for 5 years, every season I did the soil tests, the fertilization, and reseeding to no avail. I went with an organic lawn care team, and in the first season, a beautiful thick green lawn with no weeds. Now if anyone knows anything about the soil in VA, A LOT OF SAND! They did wonders! I am now in KY, and doing the organic thing on my own, this sight is extremely helpful.
I've read the ingredients to some of the enzyme additives for septic systems and they're pretty nasty. It seems like you could achieve the same thing with a narrow hole and something to cover it (a variation on Paul's post hole digger idea for lawns). Drop the waste in the hole with some leaves, hay, or sawdust to cover it. When it gets 3/4 full, top it off with with topsoil, add some grass seed and start a new one somewhere else.
Since this would be a dryer solution, it shouldn't matter what type of soil you have. I'm guessing it would improve clay or sandy soil.