Removing metallic nanoparticles from water using more advanced processes
Margarida Ribau Teixeira is a researcher at the Centre for Environmental and Sustainability Research (CENSE). She studies the treatment processes used at water treatment plants (WTPs) and suggests further processes that, alongside existing ones, could remove metallic nanoparticles from water and ensure they were safely distributed or deposited and that they would not affect the environment. The processes studied include those of coagulation, flocculation, sedimentation and flotation, activated carbon adsorption and membrane separation.
The properties that make nanoparticles so valuable in certain areas are also precisely those that are harmful both to the environment and to human health, as has been demonstrated by several studies.
Nanoparticles such as titanium dioxide (TiO2) have been widely applied in pigments, food colouring and cosmetics such as sunscreens. As these products are widely used, nanoparticles contained within them can be released into the aquatic environment during production, use or as waste, increasing the risk of contaminating the surface water used to supply populations and for recreational activities. The unique properties of nanoparticles can result in increased bioavailability and toxicity, making them potentially threatening to the well-being of both aquatic and human organisms. Part of the problem relates to the following question: “What exactly is a nanoparticle?” The most common definition nowadays stipulates that a particle is considered “nano” if its diameter is between 1 and 100 nanometres, 1 nanometre being equivalent to 1 billionth of a metre.
Currently, treatments used in WTPs are able to remove a portion of the nanoparticles. However, since metallic nanoparticles dissolve, more advanced processes are needed to remove them.
Around 1,615,000 tonnes of nanoparticles were produced in 2016, and the global volume of these substances produced/ imported into the European Union is estimated to increase by 20% by 2022. According to the researcher, “A portion of the nanoparticles produced will end up in natural waters, whether directly or indirectly, which will damage our ecosystems.”
Water is at the heart of sustainable development and is the main focus of Goal 6, “Clean water and sanitation”, which advocates for universal and equitable access to clean water and sanitation for all by 2030. As such, every effort must be made to guarantee access to safe, controlled, good quality water for the entire population. Within this goal, the project aims to contribute to the target of “improving water quality, reducing pollution, eliminating dumping and minimising release of hazardous chemicals and materials, halving the proportion of untreated wastewater, and increasing recycling and reuse globally” by 2030. In so doing, it will also help to protect marine life (SDG 14) and life on land (SDG 15).
Margarida Ribau Teixeira sees the ultimate goal of this investigation as being “to equip those responsible for controlling our water with technological tools and scientific knowledge, which will prepare them to face the growing presence of nanoparticles so that they are able to take action within their treatment systems, thus improving water quality.”
Margarida Ribau Teixeira has a Bachelor’s Degree in Environmental Engineering a Master’s in Sanitation Engineering a PhD in Marine, Earth and Environmental Sciences specialising in Environmental Technology and is a reseaqrcher for the Centre for Environmental and Sustainability Research (CENSE)