Bioremediation / phytoremediation of water

Bioremediation uses natural microorganisms to degrade, detoxify, and transform hazardous pollutants into less harmful substances. Naturally occurring organisms are used to break down the hazardous substances into less toxic, or non toxic substances. The metabolic ability of the microorganisms mineralises organic contaminants, which can be integrated into natural biogeochemical cycles (Sun & Li, 2024). Bioremediation can be effective in the removal of a variety of pollutants from water, including heavy metals, hydrocarbons, and pesticides. 

Phytoremediation uses plants and microbes to absorb, volatilise, immobilise, extract and degrade the contaminants in soil and water without producing any secondary pollution (Hadibarata & Kristanti, 2023). Phytoremediation has been shown to be an effective technique for the removal of various contaminants from water. For example, a study by Kumar et al. (2019) found that certain plant species, such as Eichhornia crassipes, can be used to remove pollutants from water, including heavy metals and organic compounds. Another study conducted by Sharma et al. (2021) demonstrated that phytoremediation can be used to remove dyes from water using the water hyacinth plant.

When planted in contaminated soil, plants take in water and nutrients and store the contaminants in their roots, stems and leaves. The plants convert the contaminants to less harmful chemicals and vapours which are released into the air. 

If you are interested in understanding the chemical, biological and technical specifics of bioremediation and phytoremediation, see further readings for a starting point to further research. See also Living Machines.

In Aotearoa New Zealand for example, Māori have always employed extensive waste management systems (Pauling & Ataria, 2010). Human waste is considered tapu (forbidden, spiritually unsafe) and discharge of human waste directly into fresh water sources harms its mauri. Waste water can only become noa (unrestricted, safe, good) through contact with Papatūānuku, The Earth Mother. Therefore, Māori object to any waste water directly entering bodies of water, even if it has been pre-treated. Using soil and plants for clean water is in line with Māori practices. (Bradley, n.d.)

Phytoremediation and bioremediation of water are effective ways to address issues of water scarcity, and water pollution, in a natural way that honours traditional indigenous belief systems. These methods reintroduce the traditional, reciprocal relationship between people, water and the natural world.

Additional considerations are pH levels, moisture, climate and other site-specific factors. Different species of plant can be used for specific filtration requirements. There is a considerable, varied range of chemical and technical factors involved in successful  phytoremediation and bioremediation of water, that depend on the site, the climate, the pollutants and ecosystems.

Each phytoremediation and bioremediation system will need to consider the specifics of the area it is being implemented in, and will require specialist knowledge of the most effective plant species, the pollutants that are being removed, the local customs, and a system of maintenance. 

Phytoremediation and bioremediation are still emerging systems, and there is a need to implement and study them in order to solidify findings.  

Systems that use phytoremediation and bioremediation to clean water can be activated across the Oceanic nations as a nature based solution that reduces GHG emissions, expands water supply and uses a natural resource to address climate change resilience.