Obviously this is a significant investment which would be much more difficult in the U.S. where egg income is lower. The biofilter consists of coarse bark mulch in trailer size containers. The air is forced in the bottom of the containers, passes through the bark and is vented to the atmosphere through the top of the containers. This is very effective in removing odors and dust. A second operation visited by our group was owned by Van Putten.
Manure is collected on belts under the cages and usually is in the chicken house about two days.
This manure is 35-40 percent moisture when it is removed and sent to a tower of belts in a chamber called a tunnel which adjoins the chicken house. Here, the manure starts on the top layer of 14 belts, then moves from end to end each time dropping to the belt below. Air is forced over each layer of the belts. In two days, the manure gets to the end of the process and it has been dried to 15-20 percent moisture. Next, the manure is pelletized and dried further to less than 10 percent moisture.