AQUACULTURAL APPLICATIONS OF AN AUTONOMOUS AQUATIC BIOMASS COLLECTOR

An autonomous surface vehicle (ASV) was constructed to collect biomass from floating aquatic species such as duckweek (Lemna minor) and to explore collection technologies that might be applied to water hyacinth (Eichhornia crassipes) and similar large floating aquatic species.  The biomass from these plants are of interest for a number of reasons.  Duckweed and water hyacinth have lipids and carbohydrates useful for biofuel production and both the raw plant biomass and the waste material from biofuel production could serve as input to animal feed production.  In addition, the removal of these species from the surface of water bodies can help improve water quality for other important aquaculture species by improving dissolved oxygen levels and reducing the biological oxygen demand on the system.

The ASV (Figure 1) consists of a dual-pontoon, dual-paddlewheel device able to operate in shallow water unattended for relatively long periods of time.  The ASV is powered by two sealed lead acid batteries which are recharged by dual 15 Watt solar panels.  The control system consists of a microcontroller and various motor controllers and a GPS unit for navigation.  The collection device consists of a system of conveyor belts and a holding tray designed to efficiently collect the biomass while allowing excess water to drain.  With a speed of approximately 3 mph (4.8 km/hr), the ASV can cover 0.5 acres per hour (2000 sq. meters per hour).  

This ASV has proven useful at collecting small species of floating aquatic plant species.  For larger water bodies, a number of these units might be used with communication such that the actions of the fleet could be coordinated for efficient collection of biomass.  In addition, larger vehicles with the ability to collect larger aquatic species are possible.