The Algae Removal Vessel, or ARVe, is a fully autonomous boat that will remove blue-green algae scums from open waters. It is a new solution designed to compete with current solutions that exist to combat HABs. This project, that builds on an earlier prototype, was commissioned and financed by Deltares and supervised by both Deltares and the Technical University of Delft.
Cyanobacterial (blue-green algae) scums represent a major problem in almost all of the eutrophic lakes and ponds in The Netherlands. Such scums have many negative effects on water quality and the overall recreational and aesthetic value of aquatic systems. A number of lake management strategies have been applied to reduce or remove cyanobacterial biomass and prevent surface scum formation:
1. Short term solutions to remove, reduce or exclude cyanobacterial biomass, for example through the use of physical barriers, mechanical and physical removal, peroxide and ultrasound.
2. Short to mid-term strategies to prevent surface scum formation or inhibit growth, for example through the use of artificial mixing using bubble plumes, chemical treatment to reduce available phosphorus concentrations or biomanipulation to enhance grazing.
3. Long term strategies to ultimately reduce biomass through nutrient limitation through the systematic reduction of external and internal loads of phosphorus and nitrogen, or the use of ecological restoration such as dredging, wetland construction, fisheries management and user-functions.
Although long term strategies are preferred the costs for Dutch water boards and municipalities are very high. Hence, alternative short to mid-term solutions are often considered.
A wide variety of methods to achieve immediate results in the short to midterm have now been tested in The Netherlands using a combination of laboratory experiments, microcosms field experiments, or whole lake pilot studies. The results have been mixed and certainly not all strategies tested have been effective. Some have even shown serious side effects (e.g. overdosing with peroxide affecting fish biodiversity). The results suggest that (1) no single (acceptable) technique is effective, (2) the best technique appears to be the use of artificial mixing (though quite costly), and (3) advanced water treatment techniques (UV, peroxide, activated carbon treatment) for drinking water should always be applied to deal with the possible presence of cyanotoxins.
With this knowledge and availing of newly available technology (robotics) it was decided to initiate a research study to work out a method that would:
• remove blue-green scums, while taking out nutrients as well;
• be cost-efficient and w/o undesirable side effects;
• include continuous sensor input to optimize the operation and at the same time further improve the Deltares modelling capabilities.
Our robot is designed to remove the scums from the water using a conveyor belt system whilst operating autonomous. This system removes the scums from the water which prevents them from forming new nutrients for new generations of scums.
The benefits of autonomy will be visible in operating costs and efficiency. Because it operates on its own it can be left alone to do it work, saving on manpower. This would allow for one or two operators to manage an entire fleet of vessels, which might not even need operators at all. Using the inbuild GPS the vessel can maintain a high accuracy in where they sail. This way they can make sure then don’t miss an inch of waterbody.
As of now we have completed the first prototype and we have tested the autonomy with success. In the summer of 2019, when blue-green algae are present again, we will continue testing and development of the filtering system.