2001 conference paper

Duckweed harvesting and mat control

ASAE 94th annual international meeting : 2001, an engineering odyssey : July 29-August 1, 2001, Sacramento, California, 1, 2277.

By: R. Smith, J. Cheng* & J. Classen*

Source: NC State University Libraries
Added: August 6, 2018

The release of excessive amounts of nutrients into the environment by NorthCarolinas hog industry has become a major concern in the state. Research is being done onthe use of duckweed, a floating aquatic plant, in the removal of nutrients from anaerobicallytreated swine wastewater. The plant must be harvested in order to remove the accumulatednutrients and to obtain the plant biomass, which may be useful as a protein source. This paperdescribes work towards the design of a system that harvests the plant by skimming it from thesurface of the wastewater. Specifically, a system was constructed in a concrete tank to test theskimming concept. Two qualitative experiments took place: one involved the harvesting of theplant under ideal conditions for skimming in which the mat was thin and no clumping of theplants had occurred, and the other under very unfavorable conditions in which the plants hadformed into clumps. It was found that a standard funnel skimmed very effectively under idealconditions, requiring very small amounts of water. The same funnel was much less effectivewhen conditions were unfavorable. The experiments showed that skimming could work verywell in a controlled environment, yet not in a typical agricultural environment. Adjustments mustbe made that can allow the system to work well in all cases.