Bioremediation / phytoremediation of water

Bioremediation and phytoremediation simplified. Image: Microbenotes

Bioremediation and phytoremediation are both effective, eco-friendly and cost-effective strategies for water treatment. Both can act as alternate methods to common modern water treatment methods such as flocculation (which uses a chemical coagulant), sedimentation methods and other technologies.

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.

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Name of NbS

 Bioremediation / phytoremediation of water

Type of NbS

Combination/Hybrid living/engineered interventions/Created or constructed living ecosystems

Location

building/single site

There are increasing concerns across Oceania about the contamination of water sources and an increase in water scarcity. Fresh water sources are increasingly polluted, which leads to the spread of waterborne diseases and health risks. This NbS can be applied in urban, periurban and rural settings on various scales. It has a variety of applications that are suitable for different locations. Bioremediation can be used either for water polluted by humans before reuse/reintroduction into the surrounding ecosystem, or to remediate polluted natural freshwater sources, such as ponds, rivers and lakes.

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Case Study

The Hawai’i Nature Center Green Machine

Earthship Timatanga (greywater)

The Green Machine. Photo by the Hawai’i Nature Center

Relationship to Indigenous knowledge

The connection between Indigenous people of Oceania, their natural environment and water is a reciprocal relationship of care and respect. Water is a sacred resource, a centre of cultural practices and an essential life source to Pacific nations.

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.

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Climate change benefits
  • Changes in phenology
  • changes in rainfall
  • coastal erosion
  • salt water intrusion into aquifers
  • flooding
  • increased incidence / distribution of disease
  • increased pests / weeds
  • loss of food production
  • reduced fresh water availability / quality

Phytoremediation and bioremediation are a simple, cost effective and in-situ strategy that uses the naturally occurring processes of plants and mircoorganisms to clean water. 

Water treatment and wastewater systems are critical to communities. Their vulnerability to, and contribution to climate change places the health and sanitation of many communities at risk (Bell et al., 2021). The increased frequency of rainfall and flooding puts pressure on water systems, and pollution, storm surges and sedimentation damage clean water resources. 

Human activities release contaminants such as heavy metals and metalloids, radionuclides, organic compounds, and oil into the air, water and soil, creating hazards and adverse health impacts on all living organisms (Hadibarata & Kristanti, 2023). 

Management of clean water is an essential and unavoidable necessity for the survival of all living organisms. Phytoremediation and bioremediation provide nature based solutions that use natural resources with a minimal environmental and social impact.

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Societal / socio-cultural benefits
  • food security
  • empowerment / equality
  • waste management and hygiene
  • fresh water security and quality

As climate change continues to seriously threaten the safety of water in Pacific communities, the very basic fundamentals of human survival are threatened. Drinking water, water for food production, waste management and sanitation are all affected by water scarcity. In the Pacific Islands, only 55 percent of people have access to basic drinking water, and just 30 percent have sanitation services (Sobey, 2022).

Phytoremediation and bioremediation can be used on small and large scales, in cities or rural communities. The strategies allow communities the ability to create and maintain their own systems of water treatment. This is especially valuable in indigenous communities in the Pacific, where nature-based strategies can provide solutions that align with traditional belief systems.

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Ecological and biodiversity benefits
  • Biological control (regulation of pests and disease)
  • Habitat provision

Polluted water increases the occurrence of waterborne diseases. Phytoremediation and bioremediation offer a way to clean water while also increasing biomass cover, and habitat provision.

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The process of phytoremediation. Image: 88Guru
The process of biooremediation. Image: 88Guru

Technical requirements

A key requirement for the success of phytoremediation and bioremediation is the correct plant species. In addition to its genotype, the plant species should have a high biomass, rapid growth, and a strong capacity for absorbing and accumulating pollutants, which is influenced by rhizo-atmospheric microbial communities, climatic conditions, and the bioavailability of pollutants (Hadibarata & Kristanti, 2023). 

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.

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Issues and Barriers

Education, training and implementation is a barrier to creating systems of phytoremediation and bioremediation of water. Modern water treatment facilities are usually run by local governing bodies, who will need to be convinced of the benefits of these systems.

As Pacific nations are increasingly battered by climate change effects, it may become easier to convince Governments and governing bodies of the benefits of nature-based solutions.

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.  

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Opportunities

As Oceanic nations look to the future, there is an urgent need to create effective, sustainable and resilient methods to deal with clean water resources. Currently, Unicef projects that “thousands of people in the Pacific Islands, including children, will be unable to access safely managed household drinking water, sanitation and hygiene services in 2030”.

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. 

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Financial case

Research shows that phytoremediation and bioremediation methods are substantially less expensive than other traditional water treatment options; in some cases five times less expensive than chemical treatment (Hadibarata & Kristanti, 2023).

References

Further resources:

  • Cross, K., Tondera, K., Rizzo, A., Andrews, L., Pucher, B., Istenič, D., Karres, N., & Mcdonald, R. (Eds.). (2021). Nature-Based Solutions for Wastewater Treatment: A series of factsheets and case studies. IWA Publishing. 
  • Diarra, I., Kotra, K. K., & Prasad, S. (2022). Application of phytoremediation for heavy metal contaminated sites in the South Pacific: strategies, current challenges and future prospects. Applied Spectroscopy Reviews, 57(6), 490-512.