How it Works
In addition to feasibility testing, the main objective of the first pilot is to examine the effects of spent brewing grains as supplemental feed on growth performance of Pacific white whrimp (Litopenaeus vannamei) in an indoor recirculating aquaculture system (RAS).
The shrimp are housed in nine fiberglass tanks, each with 10 gallons of artificially made saltwater. The tanks are covered in dark plastic and then placed within a RAS, complete with biofilters, and air tubes. In the system are a series of intake tubes that go into the filters, and outtake tubes, returning clean water to the tanks. Pumps are used to achieve the necessary cycle of water through the system. Water heaters are also placed within the tanks to help stabilize water temperatures, as they need to be fairly high for the shrimp.
Shrimp are grown from a larval state to market size (roughly 20 grams). They arrived in a bag of saltwater on an overnight flight from Miami, FL.
One of the main wastes of Pacific white shrimp is nitrogen. The biofilters, shown above, work by trickling water down through nitrifying microbes that oxidize ammonia into nitrite, and then into nitrate. Certain nitrogen molecules such as ammonia and nitrite can be poisonous to shrimp at high levels, so these microbes help the water stay as clean as possible for the shrimp. This also allows for the same water to be circulated through the system without discharge and the only reason for addition of water due to evaporation.
A series of water pumps are attached to tubes that are then placed in the tanks. The pumps work to intake water into the biofilters. One pump is utilized for three tanks, all which go into a set of two biofilters. Gravity is utilized from that point for the movement of the water from one biofilter to another, and then eventually back into the tanks.
The shrimp are fed once daily, either by hand or from the use of auto feeders. Two different sources of food are used; commercial feed and then spent brewing grain. Different tanks are given different percentages of the feed, so as to see the effect of spent brewing grain as an alternative to the traditional commercial feed.