Two-dimensional photonics – a new view of water analysis

by Thomas Jensen

Getting rid of undesired odours and off-flavours in aquaculture

This article was featured in Eurofish Magazine 6 2022.

With a strategic focus on water analysis Copenhagen Nanosystems ApS (Cphnano) offers a novel liquid-analysis platform enabled by ­next-generation cloud computing and a patented photonic sensor that expands the utility of spectrophotometric analytical infrastructure.

This allows a rapid quantification at line, which speeds the response time that decreases waste by reducing downtime or the production of a non-conforming product. Stopping production at the first appearance of the problem means the intervention is deployed only when needed. This improves performance and reduces environmental impact through better resource management.

Cphnano is among the participants in the FLAVOUR project, a collaboration between research and industry, to develop a method to detect, prevent, and remove off-flavours and undesired odours in fish farmed in recirculating aquaculture systems (RAS). Geosmin is a naturally occurring taste and aromatic compound. It is a terpene, like, for example, R-limonene, which gives orange peels their strong, characteristic smell. Geosmin is the compound primarily responsible for that unmistakable smell of mud or wet earth, recognised as the “earth odour”. Geosmin is also a terpene produced by microorganisms in soil, specifically by the streptomyces genus of the family Streptomycetaceae bacteria, which live in soil and flourish with decaying matter and produce many of our antibiotics. Geosmin is also the compound responsible for the earthy taste of beetroot and often contaminates freshwater fish. However, something that can be tasty in beetroot can be totally unacceptable in fish. Acid can degrade geosmin and, therefore, muddy tasting freshwater fish are often liberally doused with lemon juice or vinegar.

Preventing geosmin in the first place is preferable to removing it later

Geosmin-free fish are in great demand, and there is a large market for a system that detects geosmin in aquaculture water. Today, the primary method of ridding fish of geosmin contamination is by recirculating water in recirculating systems, which consumes substantial amounts of water. Rather than eradicating geosmin contamination, fish farmers want to prevent geosmin from tainting fish in the first place. Off-flavour compounds, such as geosmin, are produced by microorganisms and give the fish an unpalatable taste, even at very low concentrations. Today, the main solution is to depurate the fish in large quantities of clean water for 10–15 days. Unfortunately, the fish lose a substantial amount of weight during this period, affecting production efficiency – in addition to the environmental cost of excessive water use.

The demand for and production of fish is increasing steadily. Aquaculture is a driver in this growth with a projected increase of 37% by 2030. The geosmin problem is expected to increase accordingly as more RASs will be implemented to meet this demand which is expected to grow. The Nordic countries are a bastion of both technology for aquaculture and the production of fish. Implementing the technological solution ­developed in the FLAVOUR project is expected to increase the profit at European RAS fish farms by EUR 22 million accumulated over three years after the project’s conclusion, assuming geosmin can be removed from the fish in half the time taken by other methods. The environmental impact, realised by savings in water, is expected to amount to 100 million cubic meters. In addition, a 2% increase in production capacity is projected.

Digital laboratory analyses offers a solution

Cphnano is a Danish labtech company that has developed a new concept of digital laboratory analysis for the laboratory of the future. It was founded in 2015 and develops digital laboratory analyses for simple laboratory equipment. The company’s vision is to expand the use and increase the value of existing spectrophotometers around the world. To achieve this goal, the company strives to enable as many units as possible to perform state-of-the-art laboratory analysis and diagnostics tests. One of Cphnano‘s core products is a cuvette (NanoCuvette One), which enables regular UV-Vis spectrophotometers to replace dedicated microvolume instruments such as NanoDrop or MySpec (microvolume spectrophotometers). A disadvantage of a NanoDrop instrument is that the sample is in direct contact with the instrument, and this typically leads to problems with mechanics, optics, and biofilm after a few years. NanoCuvette One allows the measurement of 0.5 μL droplets of biomolecules using a conventional large-­volume (3 mL) spectrophotometer. The format of Cphnano‘s cuvette solution means that the optics in the UV-Vis instrument are not in contact with the sample and therefore last longer. Cphnano‘s cuvettes have a large dynamic measurement range, are calibrated from the factory in Farum, and they can be changed continuously. As the NanoCuvette One makes use of existing UV-Vis equipment, the purchase of new equipment is not necessary (no CAPEX). NanoCuvette One can be used to quantify chlorophyll content and the optical properties of water for aquaculture, which today is done using a fluorometer and transmissometer.


NanoCuvette S, analyses particles in minutes

Another of Cphnano‘s core products, the NanoCuvette S, can be used for spectrophotometric quantification of particle/cell size and concentration analysis. The NanoCuvette S can determine particles down to 50 nm, while quantifying the concentration. The NanoCuvette S allows for combined angle-resolved light scattering and absorbance at 190–1100 nm. Integrated into the surface is a patented photonic nanocrystal (optical filter) that detects light scattering so that it measures particle sizes near the photonic crystal surface. With the NanoCuvette S, particles can be quantified in minutes with increased sensitivity, reliability, and reproducibility in a standard spectrophotometer without expensive specialised instruments. NanoCuvette S can be used to establish the quality of culture water by determining the size of feed particles, and can identify the level of feed uptake in recirculating aquaculture systems (RAS). The SpectroWorks ­software automatically analyses the results. SpectroWorks is the first online cloud service for ­UV-Vis spectrum analysis that simplifies working with spectrophotometry and calculates results. It can analyse ­UV-Vis spectrum like other spectroscopy software and also calculate refractive index, particle size, and concentration, which can be used to determine plastic particles contaminating the water in an RAS plant.

Links spectrophotometers and allows control with any device

All NanoCuvettes are plastic consumables with different capabilities. SpectroLink, an IoT device, can enhance experimental workflows digitally. It ­connects spectrophotometers (currently VWR and Shimadzu, with more brands in the future) and allows control with any device such a tablet, laptop, or mobile telephone. This can be energy and time efficient with modern device technology, allowing control from one device. SpectroLink can communicate with online software SpectroWorks allowing easy, real-time access to analysis with spectrophotometers via SpectroLink. SpectroWorks is an online data platform that automates spectral data treatment, creating insights and intelligence faster and at low cost. This data platform utilises more than 200 million optical simulations to create a truly digital state-of-the-art workplace for all spectral analysis, with automatic insight reporting.

Protecting water purity in north…

Another project the company is participating in is DigiBoost. Denmark’s drinking-water supply is taken entirely from ­groundwater, and the ­quality is generally good. However, over the past 35 years, one of the substantial challenges facing the Danish drinking-water supply has been pollution from toxic materials from factories, chemicals from old waste dump sites, and insecticides, pesticides, and nitrates from farming. In the period 1998–2003, the maximum allowable concentrations were exceeded in 32% of well screens in the monitoring areas, despite regulations to prevent contamination. Over recent decades, many waterworks have been closed, forced to drill deeper, or forced to buy water from neighbouring water supplies. Therefore, it is important to monitor groundwater quality on a regular basis. However, the lack of resources, excessive cost, and lengthy analysis time limit the frequent analysis of drinking groundwater. Together with Watercare Guard and the University of Southern Denmark, the company is conducting easy, fast, and reliable real-time water monitoring at landfills where the state-of-the-art sensor technology and advanced cloud-based software SpectroWorks will be used to build a stationary unit that continuously monitors the water and delivers the result within a few minutes. A portable water testing station was demonstrated to quantify target toxins in the field at a competitive price and sensitivity using NanoCuvette One.

…and south

In the south, the company’s three-year scientific project, Photons and AI for Aquifer monitoring Needs: a cyber-physical ­system for monitoring groundwater quality (PAANEE) began in 2021 in India. Cphnano leads a consortium comprising the University of Southern Denmark, and the Indian Institute of Technology, Bombay, to develop and test a cyber-physical, AI-driven water quality monitoring system for rural communities. Water-quality monitoring in rural communities is challenging because the communities are often located far from laboratories. More than 40% of India’s rural population drink water from hand-pumped wells, yet only 7,500 of the 30 million wells in India had their water quality tested in 2015. Data from 2011 revealed that approximately 130 million people in India live in districts where at least one ­pollutant exceeded national safety standards. In this project, we are developing and testing PAANEE for rural communities. PAANEE will measure and analyse the entire water matrix via spectroscopy and cloud-based computing. Although simple, physical characteristics can be measured at the well, most chemical and biological analyses require a laboratory with technical, often bulky, and expensive equipment and specialised staff to analyse the sample. When PAANEE predicts bacterial ­contamination, the software will initiate bacterial testing at the well. Using functionalised antibodies, PAANEE will distinguish between dangerous and harmless bacteria.

For more information, contact:
Christopher Lüscher
Copenhagen Nanosystems ApS
Hørmarken 2
DK-3520 Farum

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