Haiti Biogas Project
Many communities in the developing world have inadequate waste treatment due to lack of infrastructure, limited access to energy, and inability to remove and properly dispose of septic sludge from decentralized systems. The country of Haiti serves as an example where the sanitation and energy needs are some of the most evident and pressing in the developing world.
Methods of human waste treatment are needed that exploit the large nutrient and energy content of human excreta. The lack of infrastructure in Haiti presents an opportunity for a paradigm shift to low-cost anaerobic digestion facilities. These facilities allow communities to reap benefits from their waste, including renewable energy through the production of methane-enriched biogas, treatment of the organics in the wastewater and creation of a nutrient-rich fertilizer source that has a 99% reductions in pathogens, thus providing an economic incentive for the collection and treatment of domestic waste. There were three major research activities and four major education activities that were conducted by Dr. Lansing and her research team (Andrew Moss, Katherine Strass and Kyla Gregoire) as part of a one-year NSF RAPID grant.
- Assess the wastewater and energy needs of critical medical infrastructure in a post-earthquake environment, compare this data to pre-earthquake data, and determine the resiliency of the existing system in responding to natural disasters.
- Determine the biogas potential of source-separated wastewater in order to inform anaerobic digestion design.
- Design a sustainable anaerobic digestion system to meet increased
- Led a group of six senior Capstone design students in designing an anaerobic digestion system for Cange, Haiti.
- Incorporate five sustainable technologies appropriate for Haiti into teaching curriculum in the newly created ENST 481/691 Ecological Design class.
- Development and teaching of a new class entitled: ENST 689b Sustainable Technologies for Haiti.
- Anaerobic digestion presentations to school groups, farmers, and professional societies.
Our work shows that the PIH complex displayed a high level of resiliency with regard to increased demands for natural gas and drinking water, “system inflows,” but less resiliency with regard to managing wastewater, “outflows.” As the PIH complex’s patient population returned to pre-earthquake levels, the energy needs of the hospital remained at its elevated, post-earthquake levels, due to the increased staffing infrastructure created to deal with the immediate aftermath of the earthquake, a socio-ecological change that seems to mimic changes in steady states found elsewhere in purely ecological systems. These findings are significant because we were able to quantify specific points of institutional resiliency and fragility in response to a natural disaster. Few studies of disaster management or vulnerability studies have shown the specific points at which key services (in this case, a hospital) are vulnerable to rapid system shocks brought on by natural disasters.
Population at Zanmi Lasante (PIH) in Cange, Haiti before and after the January 2010 earthquake.
Energy use at Zanmi Lasante (PIH) in lbs of propane purchased (right y-axis) and $ (US) spent per month on propane (right y-axis).
An anaerobic digestion system that treats and produces energy from latrine and black water was designed for the Partners in Health (PIH) hospital in Cange, Haiti. Wastewater samples from various sources, including latrines, black water and grey water were collected, characterized and biochemical methane potential (BMP) testing was preformed.
BMP set-up for testing methane potential at various heating temperatures.
Based on the BMP results for the source-separated wastewater, an anaerobic digestion treatment system was designed that uses black water from the external clinic to fill a tipping bucket, which flushes a latrine raceway into a three-cell digestion system with wetland/trickling filter post-treatment system. The estimated methane gas production for the wastewater entering the digester was calculated to be 38 m3 per day.
The results from biochemical methane potential (BMP) experiments of the source-separated wastewater at the Partners in Health (PIH) complex in Cange, Haiti are shown for June 2010 and Feb 2011. The wastewater sources tested included latrines, grey water, septic pits (black water), cow manure, and the control inoculum used in the BMP testing from an anaerobic digester in Beltsillve, MD.
Overview of the wastewater treatment system at the PIH complex developed by the ENST Capstone design students. Black water and latrine wastes enter an anaerobic digestion system with wetland treatment of the digester effluent and grey water.
The BMP results showed that the grey water had a much lower organic content and methane potential than the latrine wastes, and is thus directed directly to the post-treatment system. The black water, which needs further treatment due to pathogen risk but has a low solids content, is used to convey the high methane potential latrine solids into the digester. This design allows the high solids latrine wastes to be digested without the use of pumps and with a lower risk for clogging.
Construction documents were prepared for a new latrine building based on International Building Codes for seismic activity and hurricane force winds. The latrine building and anaerobic digestion system will be constructed in Summer 2011. A post-treatment system composed of wetlands and trickling filters was designed for the digester effluent and the grey water sources. Further studies are needed to determine the safety of the digester effluent for agriculture purposes due to the recent outbreak ofv. cholera.
ENST 470: Capstone Research Design Anaerobic Digestion Design for Haiti
In Fall 2010, Dr. Lansing led a senior design Capstone group, composed of six senior students from the Department of Environmental Science and Technology at the University of Maryland, in designing an anaerobic digestion system for Haiti. The students assisted in digestion laboratory experiments and chemical analyses of wastewater samples collected from Haiti. Their final project consisted of designing a wastewater system for PIH that included anaerobic digesters and treatment wetlands. Their results were compiled into a final report and presentation. In addition, the students presented a poster on their work at the American Society of Ecological Engineering meeting in Asheville, NC in May 2011. Many of the students’ recommendations were incorporated into the final design.
ENST 481/681: Ecological Design Projects for Cange, Haiti
In Spring 2010, Dr. Lansing taught and developed a new course entitled: ENST 481/681 Ecological Design to 20 seniors and graduate students at the University of Maryland. Most of the students were from the Environmental Science and Technology Department, but the class also included students from Civil Engineering and the Sustainable Development and Conservation Biology Graduate Program. This lab-based class included a design project, where the students were divided into five groups and worked throughout the semester developing a design that incorporated Ecological Engineering. Their final designs were detailed in individual 20 page technical documents and a final presentation. Due to Dr. Lansing’s Haiti research, all the class design projects revolved around Cange, Haiti. These projects included:
- an anaerobic digestion design
- a Living Machine for treating runoff from a clothes washing pad
- treatment wetlands for the digestion effluent
- agroecology for community gardens
- a green building design
Anaerobic Digestion Design for Cange, Haiti
Based on the results of the biogas potentials of source-separated wastewater, a digestion system was designed that uses black water from the external clinic to fill a tipping bucket, which flushes a latrine raceway into a three-cell digestion system with wetland/trickling filter post-treatment system
Final Overview design documents for the wastewater treatment system at the PIH complex developed by Dr. Lansing and her graduate students. Black water and latrine wastes from a latrine with a sloping raceway will enter an anaerobic digestion system with wetland treatment of the digester effluent and grey water.
Specifically, the black water is directed to a tipping bucket located at the top of a sloping raceway that is situated below the privies in the latrine building.
Shown above is the four-cell treatment wetland design for the post-treatment of the digester effluent and treatment of the grey water designed by the ENST Capstone students. The design includes two free surface wetlands and two subsurface wetlands, as well as trickling filters and rock gabion separators.
The tipping bucket provides the system an additional source of flushing force to maintain the desired velocity of the system and convey the heavy solids in the latrine. The combined black water and the latrine wastes are then conveyed into a screen housing filtration system to block non-digestible material from entering the three-cell digestion system. Each tubular digester is 12m3with an approximately 60-day retention time. The post-treatment system consists of alternating surface and subsurface wetlands with trickling filter connectors between cells.