The Project of an Autonomous Microboat with a Laser Device for Estimation of Water Area Pollution by Microplastic

Water area pollution by microplastic particles smaller than 5 mm is a serious environmental problem. Usually, studies of water pollution are carried out by taking water samples with their further analysis in the laboratory. Therefore, study of the water areas for the presence of plastic with the identification of extensive pollution sites in real time is actual.

The project of an autonomous unmanned research vehicle operating in water area and transferring the research data to the information processing center is discussed in the article. The device produces laser probing of the aquatic environment to detect polyethylene microparticles and to build maps of pollution sites in the studied water area.

To implement the proposed project, the following tasks are solved:

• detection of plastic microparticles in the studied volume of the water environment where particle sizes are several orders of magnitude smaller than the studied water volume;
• identification of microparticles in presence of particles of other types of substances in the investigated water environment volume;
• estimation of the number particles’ in the studied water environment

A new approach which consists in creating an autonomous microboat that explores the water area along a route set from a control center located on the shore is proposed. The study involves the detection of microparticles in a certain volume of liquid flowing through a research tube installed in the bottom of the boat. There is a Schauberger tube in the central part of which particles are concentrated inside the tube. It makes possible to search for particles by laser probing with a wavelength about 3.5 μm, on which the peak absorption of light by polyethylene many times exceeds the water absorption.

To ensure the energy efficiency of the microboat it is proposed to use a scheme for laser pulses combining using a fiber-optic delay line. This makes it possible to reduce the power consumption of the laser by almost an order of magnitude. The proposed project of the boat will make it possible to conduct studies of large water areas with the detection of plastic microparticles’ pollution sites. Examples of the used optical fiber, photodetector and laser source for the problem being solved are derived in the article.

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