Seaweed is not only edible, but is a particularly nutrient-dense food. Also known as "sea vegetables," you can dehydrate it like any other edible vegetable. Drying seaweed allows for extended storage without spoilage.
Harvest seaweed from a site that you trust for cleanliness. Steer clear of locations that are known to be contaminated with human waste or chemicals.
Wash the seaweed, taking particular care to remove visible debris. Washing with detergent is unnecessary; simply rinsing under plain running water with slight agitation will be sufficient to loosen impurities.
Dehydrate at a high enough temperature to evaporate water quickly to avoid mould growth, but low enough temperature to avoid the seaweed being "cooked" instead of dried. Seaweed should dry in six to 16 hours, and should be leathery when done. If using an electric dehydrator, set it on the same setting that you use for other vegetables. If using a solar dehydrator, temperature and humidity are going to be important to your ability to dehydrate. Typically you need three to four days of temperatures higher than 37.8 degrees C to dehydrate successfully, and very low humidity. This is also true when using a drying rack, with the added need for adequate ventilation for the seaweed on all sides, in order to dehydrate evenly and completely.
Some people prefer to blanch seaweed in steam or hot water prior to dehydrating, in order to retard enzymes in the seaweed and maintain texture. This is usually unnecessary, given the uses of seaweed in cooking. Besides that, blanching further deteriorates the nutritional content of the seaweed.
Spread the seaweed is spread in a single layer so it has adequate circulation on all sides in order to dehydrate evenly and quickly.