When scaling up duckweed cultivation, the first thing you want to change is the manual labour linked to fishing out duckweed from the pond. In several pilot scale projects different harvesting solutions have been proposed. The goal is to present these with some advantages and disadvantages.
The first proposed solution involves a skimmer connected to a pump, which discharges into a sieve bend. The main principle is to draw surface water containing duckweed into the pump and then separate the water from the duckweed. Since the plant must pass through the pump mechanism, it is recommended to use a pump capable of handling debris up to 11 mm in size.
A skimmer works similarly to placing a bucket just below the water surface, with the pump preventing the bucket from overflowing.
In a greenhouse pond, the skimmer can be anchored to the soil. For outdoor systems, positioning the skimmer in a corner where the wind accumulates the duckweed can be an effective alternative.
An alternative to using a pump to get a current in the duckweed pond is a paddle wheel. In the background of the following video from a pilot in Chile, you can see how this works.