You are here:
FAIR TRADE ETHANOL: FUEL PRODUCTION FROM COFFEE WASTES
Impact/Purpose:
The wastewater produced from the wet-processing of coffee places a heavy burden on the local ecosystems. Currently, there are few environmentally sound measures that monitor the discharge of this effluent. It is often discarded in a manner that disrupts both streams and the local water supplies. The purpose of this project is to design and develop a coffee wastewater treatment system that incorporates the production of ethanol and bio-gas in the remediation process. The technologies required to implement this process are well established and broadly understood, but the system we are suggesting incorporates them in ways that, to our knowledge, have never been done before. The innovative objectives of this project are:
- Determine potential ethanol production from coffee pulp and wash water for the design of scalable ethanol distillation processing units.
- Determine potential production of methane and nitrate rich effluent for the design of scalable anaerobic digestion units.
- Develop a biogas transfer system to provide process heat for ethanol distillation.
- Incorporate solar thermal and photovoltaic technologies to supply supplemental process heat and electrical pumping for ethanol distillation units.
Description:
Coffee is an important crop for developing countries, particularly in Latin America. It provides essential income to millions of people, but the wastewater generated threatens the environment and human health. The basic needs in Nicaragua are enormous, similar to many other coffee producing areas around the globe. This project has the ability to combat many of the problems facing humans today such as scarcity of potable water and energy supplies for the people that need it most. Coffee producers are all in developing nations and have serious problems disposing of the waste properly because they have no capital available to address the water contamination crisis and little environmental regulatory enforcement. Additionally, the people of rural coffee producing communities have inadequate health care so the availability of clean water is essential to quality of life.
Responsible treatment of the wastewater will reduce the impact on the local ecology, and decrease the need for human health care by improving the water quality. This effluent is discarded every day during the processing season to lagoons where it putrefies. We saw these retention ponds and smelled the putrefactions occurring; it ran-off the hill and leached into groundwater. The acids from the fermentation of sugars in the mucilage make the wastewater very acidic, down to a pH of 4.5. The wastewater samples we took in Nicaragua during January 2009, showed a pH of 4, ammonia nitrogen at >10 mg/L, phosphates of 150 g/L, dissolved oxygen of 0.01 mg/L and BOD >200,000 mg/L.
This effluent creates a potential for serious harm to human health and the environment because the contaminated wastewater is either directly discharged to streams or leaches into the groundwater tables like we saw in Nicaragua. In developing nations people rely heavily on shallow groundwater tables and surface water for drinking water supply; thus, coffee processing causes great harm to people living within the vicinity. In our survey conducted in the village of Yucul, Nicaragua, in May 2008, we learned that people could no longer drink the water because of contamination from the coffee farms above. People also were aware of the impact on aquatic life, which in turn affects fishing yields. As one woman said “the wastewater washes into rivers and hurts the people and species that depend on that water and it gives rise to famine.” Another perspective on how coffee production affects food supply came from one man who said “We know that wastewater from coffee production is polluting the water but people in this area are poor and have to eat, have to have some income to buy what they need and for most, coffee picking is the only work available.”