When dealing with polymer-dewatered biosolids, the composting mix should include more bulking agents or dry amendments to handle that extra water. Oily materials Materials that contain oils, such as some types of fish, can cause problems in the composting process. The first, and perhaps most apparent problem, is the persistence of an oily odor that lasts for weeks into the composting process, even after the material is no longer visible. A second problem is that oily materials generally break down more slowly than expected. A third effect is that oils indirectly impact process control.
Oil lends the materials a sheen that can be mistaken for moisture.
Oily materials can be composted, but only in amounts less than ten to 20 percent of the mix by weight. Additional curing time may be necessary to obtain mature compost from oily feedstocks. Composting needs air, but too much can be a detriment to the process. Particularly in a forced aeration system, where blowers provide the air, excessive air flow can remove a lot of moisture. The problem is aggravated by the channeling of air that occurs within piles at high air flow rates.