Vegetation as Sanitation: How Plant and Water Microbial Diversity Impact Greywater Treatment in Earthships

Anthropogenic impacts pose a pressing crisis to human, environmental, and ecosystem health (IPCC, 2014). Fortunately, already existing holistic, affordable, and sustainable solutions pose a great opportunity to alleviate the systematic societal, economic, and environmental issues caused by the human degradation of the planet and its ecosystems. Water, the fundamental component in all life, is a top priority for human and environmental health. Fresh water scarcity is already a global issue that is projected to become exacerbated under the changing climate, however there are many water saving measures that can help address this issue. In order to address potential solutions to the issue of fresh water scarcity, my research focuses on the use of vegetation to treat and reuse greywater in a type of sustainable building called an Earthship. An Earthship is an architectural style of fossil fuel free home that uses natural and garbage materials to make buildings that heat and cool themselves through passive thermal and solar gain, generates their own solar electricity, harvests their own water, has self contained sewage treatment, as well as food production. In this research I targeted the functionality of the Earthship greywater reuse system that consists of a series of vegetated planters, which double as food production within the Earthship outer greenhouse. I hypothesize that plant and microbial diversity in Earthship greywater treatment planters impact their functional capacity to treat household greywater. In order to test my hypothesis I collected data on multiple parameters to account for the potential factors at play in these systems, ranging from water quality tests, heavy metal analyses, plant surveys, and microbial analyses for 16s RNA and intI1 to make inferences on bacterial community composition throughout the treatment process, as well as the occurrence of pathogenic bacteria. Together these results can inform the performance of these systems in relation to potential health risks associated with wastewater. This research aims to establish a baseline for variability across Earthship greywater systems so that these results may inform future design optimization for sustainable solutions targeting effective greywater reuse strategies in order to address the global fresh water scarcity crisis and effluent treatment issues