Water analysis

Particle analysis has numerous applications in water sample analysis, including environmental research, drinking water production, and waste water treatment. Our holographic particle tracking method can identify and differentiate a wide range of particles based on their refractive index and shape. Different particles of interest in water samples include bacteria, viruses, minerals/clays, microplastics, rubber, oil droplets, rust/metal, and more.

In environmental research and surveillance, samples of fresh water, storm water, and sediment are analyzed, often focusing on organic particles like microplastics, rubber, and oil droplets. Holographic particle tracking can be a valuable tool for studying such particles in the micron and submicron range, as harmful substances in the environment often attach to and are transported by these particles.

In drinking water intake and processing it is important to detect and identify bacteria and virus particles, as well as oil droplet contaminants. Bacteria are typically in the size range of 0.5-5 mm and can often be identified by their shape.

In waste water treatment, the effluent usually contains bacteria and a large number of virus particles generated in biological treatment processes. Holographic particle tracking can help identify and quantify these particles and others, allowing for more effective waste water treatment.

As a demonstrative example, we analyzed a sample of effluent water from a municipal waste water plant. For a selection of particles >0.6 micron, the length/width ratio was determined by a deep learning algorithm, and those with a ratio>1.5 were arbitrarily considered to be bacteria. Their refractive index was determined to be about 1.38 which is in accordance with literature values for coli bacteria. This demonstrates that bacteria can be selectively counted and it is expected that different types of bacteria can be differentiated based on their shape and morphology.