Microalgae here and there. It is odd not to have come across some news about the use and the thousand applications of these microorganisms that a few years ago we simply knew as those that dye the colour of salt water and fresh water.
Microalgae are a beneficial source for humanity, spreading its application to food, agriculture, aquaculture, pharmacology and cosmetics, among others. They can also generate clean energy, second-generation biofuels, bioplastics and biofertilisers, thus contributing to the development of the circular economy.
They can grow in an autotrophic or heterotrophic mode. In the first case, they use sunlight as an energy source and CO2 as an inorganic carbon source, consuming nutrients and producing oxygen. While in heterotrophic growth the only source of energy or carbon are organic compounds.
Heterotrophic microalgae have a great capacity to absorb organic carbon and various types of nitrogen and phosphorus compounds from wastewater without the need for sunlight. This is therefore a great opportunity that allows the treatment of wastewater in almost any closed tank, greatly reducing the treatment area to be used.
LIFE ALGAECAN project
The LIFE ALGAECAN project, coordinated by CARTIF, proposes a new system for the sustainable treatment of effluents from the agro-food industry through the cultivation of heterotrophic microalgae, obtaining a high quality by-product as raw material of commercial interest. This by-product is intended to be used as a biofertiliser and/or animal feed.
Effluents from fruit and vegetable processing and washing are an ideal raw material for microalgae growth, because they have a lower pollutant load than other industrial effluents and are really rich in nutrients.
The demo plant has been installed and operating for six months in the facilities of the company HUERCASA, in Segovia (Spain), carrying out the treatment of its wastewater from the processing and washing of vegetables and achieving the profitable growth of microalgae in closed reactors without light.
Is this treatment environmentally and economically beneficial?
The project consortium has designed and developed this treatment prototype, powered by renewable energies, specifically solar energy and supported by biomass, with the aim of minimizing the carbon footprint and operating costs.
Furthermore, an economic benefit will be obtained from the sale of the microalgae obtained as a biofertiliser, since microalgal biomass contains micro and macronutrients, especially nitrogen, phosphorus and potassium, which can help improve soil fertility and stimulate plant growth.
The results obtained have been favourable so far, since treated water is obtained within the legal parameters for discharges in addition to the complete elimination of the sludge generated in the traditional treatment process of this type of wastewater in aerobic conditions.
The project’s latest aim is to replicate the results in other locations and for the next six months the plant will be operating in the second demonstrator at the VIPÎ facilities in Slovenia, where the environmental conditions are different.
The project consortium is formed by the Technology Centres CARTIF (as coordinator) and AlgEn (Slovenia), the companies HUERCASA (Spain) and VIPÎ (Slovenia), and the University of Athens (Greece).