Final Report: Small Scale Ecosystem Engineering: Development of Household Level Greywater Treatment SystemsEPA Grant Number: SU835498
Title: Small Scale Ecosystem Engineering: Development of Household Level Greywater Treatment Systems
Investigators: Rejmankova, Eliska , Chavez, Ariel , Gee, Brian , Jian, Mathew , Lehyan, Jamel , Leu, Wayne , Leverenz, Harold , Ortega, Eduardo , Taghavi, Imaan
Institution: University of California - Davis
EPA Project Officer: Packard, Benjamin H
Project Period: August 15, 2013 through August 14, 2014
Project Amount: $14,969
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2013) RFA Text | Recipients Lists
Research Category: P3 Challenge Area - Water , Pollution Prevention/Sustainable Development , P3 Awards , Sustainability
Greywater is wastewater that does not come from toilets. Primary sources of greywater in households include sinks, showers, and laundry machines. Greywater treatment at the household level is becoming increasingly recognized both in the U.S.  and internationally. However, many household-‐level greywater system designs remain relatively simplistic by using only water quality as the design driver. To achieve maximum benefit of passive greywater systems, modifications and monitoring of designs are necessary.
We proposed to develop a household-‐level greywater treatment system that integrated the natural treatment capabilities of bacteria, fungi, earthworms, and plants within a small-scale ecosystem. The household greywater treatment system, coined the “Infiltration Station,” was primarily implemented in the city of Chocolá, Comunidad Agraria Chocolá, Suchitepequez, Guatemala to test the significance of such a system in the developing world. Due to the unforeseen circumstance of difficulties in acquiring fungi and earthworms for artificial inoculation of the system in Chocolá, we opted to only apply plants to the Infiltration Station.
Through the use of plants, this project addressed three technical issues: 1) removal of pollutants in water, 2) water reuse, and 3) increased nutrition. The main component in removal of pollutants is phytoremediation, or the use of plants to contain, extract, or degrade contaminants in the soil or water. Reuse potential of greywater has become increasingly recognized, and studies suggest that treated greywater can effectively irrigate crops without detrimental effects on soil or plant growth [2,3,4]. Furthermore, plants irrigated with greywater tend to have higher nutrient content [5,6]
Our design also incorporated a gradual distribution mechanism to release greywater at a slower rate and across a greater area. To test the efficacy of a gradual distribution mechanism on removal of pathogens, we used a tipping bucket system for intermittent dosing in Davis, California.
Key developments during Phase I include:
- Greywater composition of Chocolá was quantified
- Nitrate, ammonium, and orthophosphate composition in greywater was compared to other literature studies
- Community members dismantling of the Infiltration Stations hindered long-‐term maintenance and analysis of the systems
- Efficacy of tipping bucket system for intermittent dosing analyzed with potential errors being considered.
Because community members in Chocolá disassembled the Infiltration Stations, we were unable to quantify the treatment effectiveness of the systems. However, greywater composition was still quantified. Low amounts of orthophosphates in greywater may indicate increased community environmental awareness; however, nitrate composition is extraordinarily high.
In the mean time, Semillas Para El Futuro, our partnering non-governmental organization in Chocolá, has agreed to help create a display for the town showcasing plants irrigated with greywater and drinking water to provide a visual form of education to the community.
The pilot study in Davis, California will continue to test and optimize the components of the Infiltration Station. It also has simultaneously become an education tool for aspiring undergraduate students to understand water quality testing, sand filtration, and most importantly lead a research study with all the lessons that comes with it.