Biofilters: Biofilters can be used to convert ammonia nitrogen into nitrate nitrogen, which is a nutrient for algae [93]. Drum, disk, bead and sand filters are commonly used to capture and remove particles as small as 60 microns from the water [93].
Leachbed (LB)-up-flow anaerobic sludge blanket (UASB) to treat dead chickens: In this system, one UASB (35 or 55 C) plus 3 LB reactors were used. A closed-loop pair consisting of a LB and an UASB reactor treated dead chickens in 118 days. This system had better efficiency at 35 C than 55 C [94].