Water and soil are two major elements that are needed to secure the health and well-being of us humans and other organisms on this planet. Not only do these two domains provide a setting for us to live and thrive in, but healthy soil and clean water are prerequisites for the securing of the food chain for us and for the generations to come. Today, however, environmental pollution of both water and soil is of growing concern.

The environmental pollution is man-made and originates from a range of sources. Industries release toxic byproducts and contaminated wastewater, and agricultural fertilizers and pesticides seep into the ground. Other sources that contribute are untreated sewage, oil spills, radioactive contamination and acid rain, all of which pose a hazard to human health. At the same time as we are witnessing this degrading of two of our most important natural resources, we see a population increase and a growth in global wealth. More people on the planet and more people leading a high-consumption lifestyle puts pressure on available resources to support an increasing consumption and changing consumption habits. To meet the consumption needs and secure the supply of both healthy soil and clean water, there is a need to clean up the contaminated water and soil.

Water purification by filtration

Clean water is an increasingly scarce resource. High-quality water is needed not only to serve as drinking water for an increasing number of people on the planet, but also to support the agricultural and industrial production of food and clothes to support a high-consumption lifestyle. To secure a sustainable water supply for future generations and to provide safe habitats for aquatic creatures, we need to be more resource-efficient and recycle the water that we use. We also need to purify already contaminated water sources, such as rivers, lakes and oceans. In regions where the fresh water supply is scarce, recycling together with desalination may provide a solution to the consumption needs.

One effective way of addressing water contaminants is membrane filtration, which can be used in water recycling, reuse as well as in desalination. QSense® QCM-D can be used in the development and evaluation of filtration membranes, to characterize membrane swelling and the filtration properties of, for example, reverse osmosis membranes for desalination and wastewater treatment, as well as membrane fouling.

Soil purification

Soil remediation is a process where the contaminated soil is either removed or purified using different means. One of the most interesting approaches for soil purification is bioremediation. In bioremediation, micro-organisms are used to break down the contaminants within the soil. Bioremediation is most typically used to treat organic contaminants such as oils and petroleum-based fuels.

The major difficulty in bioremediation is the availability of the contaminants, as these hydrophobic compounds bond with soil particles and have low solubility in water. To enhance the contaminants’ contact with micro-organisms, and thus biodegradation, surfactants are utilized. Surfactants are used to enhance the desorption and solubilization of petroleum hydrocarbons, thereby facilitating their assimilation by micro-organisms.

Most commercially available surfactants are synthesized from petroleum by-products. However, the increasing environmental concern has led to research and development for alternative natural surfactants to replace the existing products. These biosurfactants are typically glycolipids, lipoproteins, phospholipids, fatty acids or polymeric in their chemical nature. At low concentration, biosurfactants are soluble in water, but at higher concentration they form micelles. The point at which micelles are formed is called the critical micelle concentration (CMC) point. The critical micelle concentration of biosurfactant solutions is routinely measured, as solubilization of the petroleum hydrocarbons typically takes place above the CMC. From both an economic and environmental point of view, it is important to use as small an amount of surfactant as possible.