Bioresour Technol. 2010 Jun;101(12):4362-70.
Methane production in low-cost, unheated, plug-flow digesters treating swine manure and used cooking grease.
Lansing S, Martin JF, Botero RB, da Silva TN, da Silva ED.
Department of Environmental Science and Technology, University of Maryland, 1445 Animal Sci./Ag. Eng. Bldg., College Park, MD 20742-2315, USA. slansing@umd.edu
A co-digestion investigation was conducted using small-scale digesters in Costa Rica to optimize their ability to treat animal wastewater and produce renewable energy. Increases in methane production were quantified when swine manure was co-digested with used cooking grease in plug-flow digesters that operated at ambient temperate without mixing. The co-digestion experiments were conducted on 12 field-scale digesters (250 L each) using three replications of four treatment groups: the control (T0), which contained only swine manure and no waste oil, and T2.5, T5, and T10, which contained 2.5%, 5%, and 10% used cooking grease (by volume) combined with swine manure. The T2.5 treatment had the greatest methane (CH(4)) production (45 L/day), a 124% increase from the control, with a total biogas production of 67.3 L/day and 66.9% CH(4) in the produced biogas. Increasing the grease concentration beyond T2.5 produced biogas with a lower percentage of CH(4), and thus, did not result in any additional benefits. A batch study showed that methane production could be sustained for three months in digesters that co-digested swine manure and used cooking grease without daily inputs. The investigation proved that adding small amounts of grease to the influent is a simple way to double energy production without affecting other digester benefits.
{ 1 comment… read it below or add one }
BioEarth has a contract to supply and install 20,000 BioGas Digesters in rural Kenya
as part of the K-Rep Development Agency/ BioEarth Clean Cooking in Kenya Initiative.
We will provide BioGas plants and Improved Cooking Stoves throughout the country.
I am encouraged by your findings and wondered if you tried adding anything else to try to improve
Methane production. Specifically, did you try any microbes? Have you tried adding various portions of
field waste or ‘Energy crops’. There has been success with both additives in Europe.
We are working on improved digester designs and would like more information form your studies.
Are you set up to do additional testing in Costa Rica?
Do you think there would be an interest in replication our project in that region?
I would be open to any thoughts of comments,
Brian Raab
President
BioEarth inc
brian@bioearthinc.com