The market
The global market for filters and filtration systems reached $45 billion in 2010. Automotive filters represented the largest market segment. Filters for separating suspended solids from water and air totaled $25 billion in the same year. The fastest-growing segment was liquid filter cartridges, valued at $13.6 billion. Other markets included liquid macrofilters ($1.3 billion), fabric filters ($2.3 billion), and cross-flow membranes used in reverse osmosis ($1.9 billion). The Chinese market, at 14%, was the fastest-growing in the world for filter consumption. However, in 2010, China remained a major importer of equipment. This trend is expected to reverse soon. Given the continued market expansion, China is expected to become the world's second-largest consumer of filters after Japan by 2015. The narrowly defined market for indoor air filters reached $6.6 billion in 2010. A wide range of techniques are used to remove solid particles from the air, including dust, pollen, mold, bacteria, and even dust mite droppings. Air purification helps prevent the distribution of airborne contaminants that could otherwise lead to sick building syndrome. Air quality is improved through simple physical and mechanical barriers, ultraviolet radiation, ozone sterilization, activated carbon, and electrostatic removal. Commercial and office buildings represent the largest segment, closely followed by industrial facilities. Demand for high-efficiency filters is concentrated in the electronics sector, while solar cell manufacturers have a growing appetite for filters. Although the residential market remains modest, the projected growth rate of 5.2% is significantly higher than that of the global economy. The search for healthy indoor conditions, particularly in polluted urban environments, is driving this continued expansion in demand.
Innovation
The use of filters generates a trade-off. As the filter is designed to remove increasingly smaller particles, the airflow pressure drops. Thus, the more efficient the filter, the more energy is required to maintain the overall efficiency of the air circulation system. This means that most energy-efficient filtration systems are actually the least efficient particle separators. The search for innovation has therefore focused on filtration technologies that improve removal while decreasing the energy input required. This has led to innovative approaches such as the use of TiO2 (titanium dioxide) nanoparticles and ozone. While replacing a mechanical process with a chemical one succeeds in reducing airborne contaminants, these approaches to cleaning indoor air create harmful byproducts. Substituting physics for chemistry is an innovation best avoided. Professor Lars Thofelt observed particles floating around the globe in the atmosphere and falling into tropical rainforests. He wondered how plants, soil, and water interact in an ecosystem where solids are transported by the air circulating through the plants, adhere to the leaves, and are eventually washed down to the soil where everything decomposes and generates even more soil. He observed that most buildings have hot, dry indoor air and devised a method to add humidity. This reduces irritation of the mucous membranes while purifying the air. He also noted that tiny particles stick to larger ones. These are usually trapped by ventilation filters, but once the larger particles dry out, the smaller ones are released again. The human body's natural filtration system is unable to block them. In the early 1990s, Professor Thofelt designed a miniature version of a rainforest with up to 150 plants. He learned how a healthy rainforest maintains a balance between regrowth and decomposition. He worked with Anders Nyquist, the architect who envisioned how the air within the building could naturally circulate through the tropical garden, ensuring the removal of most large particles before they dehydrated, while capturing all the smaller particles along with them. This innovative architect, with an unparalleled track record in the field of eco-building, achieves this natural flow by harnessing the interplay of light and pressure. While plants are welcome in buildings, they are generally considered an expense. When plants are converted into a filtration system within the building, this green space offers multiple functions, thus reducing costs. This is a typical feature of the blue economy.
The first cash flow
Professor Thofelt then founded Levande Filter AB in Sundsvall, Sweden, and built several test cases to demonstrate the power of a micro-rainforest to recreate a healthy and pleasant indoor climate while reducing the risk of infections and allergies. The need for chemicals is replaced by an interaction of the laws of physics with the predictable functioning of ecosystems. One of the first projects was the Laggarberg School in Timrå, Sweden, some 400 kilometers north of Stockholm (1998). A second case is Midlanda Airport (Sundsvall), with a mix of plants, bushes, and small trees under the roof. Because warm air always rises and the mist settles dust, the air is clean. The initial experimental projects were a resounding success, proving that the process is not only effective and aesthetically pleasing, but also saves considerable energy and money. Test results from independent auditors established that the living filter reduced carbon dioxide levels, which had reached a peak of 735 ppm, to 300-350 ppm, comparable to good outdoor air quality. The plants removed CO2 at a rate of 9.42 grams per hour. Perhaps even more impressive was the removal of 7.5 µg of formaldehyde per hour!
The opportunity
The team at Levande Filter AB made progress in designing standard cabinets equipped with automatic watering and a timed lighting system. The Ford dealership in Umeå decided to install several cabinets in their workshop. Toluene and hydrocarbons were managed naturally. Based on these positive results, the company expanded to Finland, the Netherlands, and North America. While plants are expected in public spaces, the growth of bird's nest ferns, vines, elephant's foot, Queensland umbrellas, and even pepper and banana trees is an enriching experience for everyone, especially when the filter is installed in schools. Not only do children grasp the functionality and importance of the rainforest in their environment for maintaining their health, but they also learn more about biodiversity than ever before in a biology lesson. The interplay of light, humidity, the economy, innovation, ecosystems, and health is becoming a way of life. This is how the blue economy succeeds in making health a priority, and its cost affordable, while beauty is a bonus.
