Bioreactor Gardens, Hawai’i
Bioreactor garden bed, Hawai’i
Project Summary
Untreated wastewater making its way into groundwater and coastal waters pose a huge threat to ecological and human health. A bioreactor garden leverages natural processes of plants, soil, and microbial activity to clean water coming from septic systems. Proper wastewater treatment protects human communities, saves coral reefs & preserves the environment. Combining methods from denitrifying bioreactors, sand filters, and phytoremediation systems (i.e. plants), bioreactor gardens effectively reduce the primary components of waste water: ammonia, nitrate, phosphorous, and bacteria.
Problem
In Hawai’i alone, there are 88,000 leaking cesspools and many underperforming septic tanks transporting 53 million gallons of minimally treated wastewater each day to coastal watersheds. This creates huge impacts on the health of local water and the rich coral reef ecosystem. These can be largely remediated with bioreactor gardens.
Solution
Bioreactor gardens are easy to maintain and can be placed in series with a septic tank to provide effective secondary treatment for any size on-site disposal system.
Implementation
Bioreactor gardens are relatively simple to build and sustain. Vegetation break down pollutants and absorb the overall water volume in the system. Microbial processes in the soil convert compounds, rendering them safe for the environment. Biochar and wood chips host denitrifying bacteria which safely convert pollutants to harmless compounds.
Outcomes
Early nitrogen removal data is showing that the bioreactor garden pilot project works as expected and designed! Water running through the bioreactor gardens is flowing out much cleaner, with measurably low nitrogen concentrations.
Funders and Partners Mahalo to Woodard and Curran Foundation for funding this work, Dr. Roger Babcock and University of Hawai’i’s Water Resource Group for performing the testing and certification, WAI (Wastewater Alternatives & Innovations) for serving as an important technical and advocacy partner, Orrin from Malama Tree Care for the free wood chips and good vibes, and Allen Fanning and American Water staff for assistance in constructing the system!
