Researchers in Colombia have developed a way to turn cheese whey and cattle manure into biogas, providing a dairy farm with enough renewable energy to meet its entire propane requirement for cheese production, World Bio market Insight reported.
The project, led by Miguel Casallas of the University of La Sabana, is being implemented in Ubaté, Colombia’s second-largest cheese-producing region. The initiative addresses a significant waste-management challenge in the area, where producing one kilogram of cheese generates around nine kilograms of whey.
When left untreated, the whey can enter rivers and soil, creating environmental problems in a region heavily dependent on dairy farming.
Casallas and his team tested more than 100 combinations of whey and cattle manure to identify a suitable feedstock mix for anaerobic digestion. They eventually selected a blend containing 65% whey and 35% cattle manure.
The mixture was fed into an eight-cubic-metre pilot biodigester, where microorganisms decomposed the organic material in the absence of oxygen. Following a three-month stabilisation period, the system began producing biogas.
The renewable gas now supplies the farm’s entire propane requirement for cheese-making and is also used to heat accommodation for workers living on the farm.
The combination of fossil fuel savings and reduced pollution from untreated dairy waste has lowered the carbon footprint of the farm’s cheese production by 43.6%, according to the researchers.
The anaerobic digestion process also produces a residual material known as biol. While the researchers said it is not sufficiently concentrated to qualify as a fertiliser, it can be used as a soil improver on grazing land.
Farmers using the biol have reduced their consumption of inorganic fertilisers, including urea, by as much as 50%. The resulting savings are estimated at around $410 per month.
However, the research team has cautioned against directly replicating the system across farms without site-specific assessment.
Factors such as temperature, feedstock quality and cattle diets can influence the performance of anaerobic digesters and the resulting biogas output. Casallas said each farm therefore needs to be assessed individually before a biodigester is designed and installed.
The project demonstrates how dairy waste that would otherwise create environmental problems can be combined with livestock manure to produce renewable energy while reducing fossil fuel use and fertiliser consumption.
