Handling of liquid or slurry waste from buildings involves scraping or flushing the waste from where it is dropped by the animal to a pit or a storage tank. Once collected, the waste is treated and/or disposed. Open feedlot waste is handled as runoff-carried waste, with natural precipitation carrying the liquid or the slurry, flowing from the pens into a drainage and collection system for subsequent removal or treatment and disposal. Liquid waste usually is handled by pumping, and is disposed of by being spread on the surface of or injected into the soil. The maximum amount of waste that can be spread in liquid form is determined by using the same procedure as that used for solid waste.
Liquid waste is more difficult to manage than the solid because it must be stored in tanks or pits and must be pumped. In addition, because animal waste should not be spread on frozen ground, the storage unit must have the capacity to store all of the waste while the ground is frozen.
Problem: What size of above ground tank (gal) is required to store all of the waste from a 100-sow farrowing barn if the pigs are with the sows, and the waste must be stored for 6 weeks?
Solution: Using Appendix VI and units cancellation (Note: weights can be converted to volumes if the density is known):
1 gal 1 ft3 33.0 lb 7.0 day 6 weeks 100 sows gal =-5- x -x -x -x -x -
An additional problem that arises using liquid waste is the space required for the storage tank.
Problem: How high will a round tank be in the previous problem if the space available for the tank is 20.0 ft in diameter?
Solution: This is a good problem to use the units method.
0.13368 ft gal
17,300 gal 1
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