We had a home made system. We used a tank which had to be heated via a water jacket to keep the slurry @100 to 105 approx. The gas was piped into an above ground pool with a stainless steel dome which floated on the water. You need to have some sort of pressure controlled collection system. The gas would perk up thru the pool. The weight of the stainless steel dome would serve as a regulator. It would rise and lower based on volume of gas with a steady output pressure. Our problem was microbial blooms and die-offs. The blooms resuled in a lot of methane belches which would ignite on occasion since we had the burner for the heating system about 50' from the pool.
I guess if you kept your holding/regulating system far away from the barns (like 1000'), that would work better.
I guess if we'd spent a few million on technology we'd have come out better. We spent about $2,500 and used scrap/farm fabricated materials. We could have used it for our house needs from May thru September. Once it dropped to the teens and below it was not feasible. Too much energy spent to heat the slurry.