The Hawai’i Nature Center Green Machine

Name of case study

The Hawai’i Nature Center Green Machine


  • Makiki Valley
  • O’ahu
  • Hawai’i




Building / single site

Area / size


NbS employed

Type of NbS

Created or constructed living ecosystems


Hawai‘i Nature Center


The Environmental Protection Agency. Malama I Ka ‘Aina, a U.S. Department of Education grant, provided funding for the operation and tours of the facility.



Design group

Roth Ecological Design (REDI)

The Green Machine. Photo by the Hawai’i Nature Center
The Green Machine. Photo by the Hawai’i Nature Center.
Climate change benefits
  • Changes in rainfall
  • Drought
  • Loss of food production
  • Reduced soil quality
  • Reduced water quality
  • Reduced fresh-water availability

As climate change impacts Hawai‘i with decreased rainfall and an expanding population, the Green Machine offers a wise solution for conserving freshwater resources while effectively treating wastewater.

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Societal / socio-cultural benefits
  • Food security and quality
  • Waste management and hygiene
  • Rights / empowerment
  • Water security and quality

The Green Machine is notable for its educational benefits. It primarily works to clean waster water and recycles this as irrigation for food production.

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Ecological benefits
  • Decomposition
  • Food production (for humans)
  • Fresh water
  • Genetic resources (diversity)
  • Habitat provision
  • Nutrient cycling
  • Purification (of water, soil, air)

By utilising natural processes like biological filtration and nutrient cycling, the Green Machine effectively removes pollutants and contaminants from wastewater, resulting in improved water quality. This contributes to the preservation and restoration of aquatic ecosystems and reduces the impact of pollution on local water bodies.
The diverse array of native plant species and aquatic organisms housed within the Green Machine provides habitat and refuge for various wildlife species. This promotes biodiversity and ecosystem resilience by supporting native flora and fauna, including endangered or threatened species.

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Summary of case study

The Green Machine, formerly known as the Pilot Living Machine, is a tank-based constructed wetland wastewater treatment facility situated in the Makiki Valley State Recreational area in Honolulu, Hawai‘i. It cleans and recycles wastewater for both the Hawai‘i Nature Center (HNC) and the Department of Land and Natural Resources (DLNR), Division of Forestry and Wildlife (DOFAW) Baseyard.

The HNC obtained funds to construct a new education classroom in 2006.  Connecting this new building to the city’s sewer system was not practical or financially viable, so the Green Machine was brought to Makiki Valley as an affordable wastewater solution with educational value. Some time later the nearby DOFAW Baseyard connected to the Green Machine when their septic tank system became obsolete.  In 2016, ownership and maintenance of the Green Machine was transferred to the HNC with consultation and support provided by REDI. HNC continues to partner with DOFAW for the management and maintenance of the Green Machine as a wastewater treatment system and educational tool. 

This initiative is particularly important in illustrating alterative water treatment systems in  Hawai’i as rainfall decreases in the islands due to climate change, compounded by an escalating island population. Drought conditions have become more frequent and the number of yearly tradewind days has decreased over the past several decades, meaning less consistent rainfall to replenish groundwater supplies (Gazra, Chu, Norton 2012).  The Green Machine is able to exceed Hawai’i Department of Health R-3 reuse level standards by meeting criteria of 10 mg/L of total dissolved solids and 10 mg/L biochemical oxygen demand, and incorporates R-2 reuse level practices of both oxidation and chlorine disinfection (Roth Venu 2015). 

Recognising the value of freshwater and taking measures to protect it are part of traditional Hawai’ian practices.  The constructed wetland technology uses the biological processes of native Hawai’ian wetland plants and bacteria to naturally purify the water. Comprising a metal tank partitioned into 7 sets of treatment cells (14 cells in total), the Green Machine hosts a diverse array of microbes, native plant species (such as kohekohe and makaloa), and small aquatic organisms, facilitating nutrient recycling and natural wastewater treatment similar to a natural wetland ecosystem. The Green Machine was situated so that treated wastewater from HNC would be pumped to a nearby an irrigation field to establish and cultivate a collection of native and Polynesian-introduced plants featuring loulu, koa, and ‘ōhi‘a lehua. 

The HNC has showcased the Green Machine to demonstrate environmental science concepts and has integrated principles of biomimicry into curricula, illustrating nature-inspired sustainable design as a viable solution to contemporary environmental challenges. As a self-contained, constructed wetland situated within an environmental education center in a valley, the Green Machine offers a unique opportunity to observe firsthand the benefits of a natural wetland. Understanding the mechanisms behind the Green Machine underscores the importance of wetland conservation both locally and globally.

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The Green Machine. Photo by the Hawai’i Nature Center.
  • Garza, JA; Chu P, Norton CW, Schroeder TA. Changes of the prevailing trade winds over the islands of Hawaii and the North Pacific. Journal of Geophysical Research. 2012; 117(D11109): 1-18.
  • Roth Venu, L.C. (2015). Ecological Design for Island Water Systems. In Chirico, J & Farley, G.S (eds) Thinking Like an Island: Navigating a Sustainable Future in Hawai ‘i. University of Hawaii Press.

Further resources:

<< Living machines / ecomachines << Bioremediation / phytoremediation of water << Wetlands: constructed