University of Illinois researchers Yuanhui Zhang and Lance Schideman, both professors in the Department of Agricultural and Biological Engineering, have combined their research efforts to develop an innovative system that uses swine manure to produce biocrude oil, grow algal biomass, capture carbon, purify wastewater, and recycle nutrients. Zhang has spent more than a decade researching the conversion of swine manure and biomass into crude oil. Schideman has done significant research in the area of integrated algal systems for wastewater treatment and bioenergy production.
“We first convert swine manure into crude oil in a hydrothermal liquefaction reactor,” Schideman says. “There is a very strong wastewater that comes off that process. It contains nutrients that can be used to grow algae that simultaneously clean the water. Lately, we’ve added low-cost, bioregenerable adsorbents into the system that allow us to grow additional bacterial biomass and further improve effluent water quality.
“Our recent research, a combination of experimental work and some computer modeling, has shown that we can reuse the nutrients multiple times and thus amplify biofuel production from waste feedstocks,” he explains. “If we start with a particular waste stream that has one ton of volatile solids in it, we might be able to produce three, five or even ten tons of algal and bacterial biomass. This new biomass is then recycled back into the biofuel production process,” he continues. “It can also clean the water with the goal of making it suitable for environmental discharge or reuse in some other application. So we get more bioenergy and more clean water resources – both good things in the long run.”
Schideman says they are also focusing on developing markets for the downstream products of the biocrude oil. “This crude oil is similar to, but not exactly like petroleum. It generally has higher oxygen and higher nitrogen content than traditional petroleum, but lower sulfur content. Some of those things are positive, some are negative, but regardless, they’re different. We have to understand those differences in order to make the new materials compatible with existing infrastructure.”
In the near term, Schideman says that “bridge” markets are likely needed to begin using biocrude oil products on a smaller scale than current petroleum refineries. “Refineries need hundreds of thousands of barrels of material each day,” he says. “It can be a chicken and egg kind of question. We have material, but not that much. And you don’t want to build or modify a refinery unless you have more material.”
Schideman says one bridge market to consider is blending light fractions of the oil into existing fuels. “Right now, your gasoline has a certain amount of ethanol mixed in it. We are looking at other blending arrangements where light fractions of this oil could go directly into an existing fuel matrix.”
Schideman notes that the heavy fraction can potentially be used in asphalt-like products. “Innoventor, an engineering and design firm near St. Louis, licensed some of Professor Zhang’s earlier work and converted animal waste into a bio-oil product used in pavements,” he says. “They made an asphaltic binder and paved a 500-ft. stretch of road to Six Flags St. Louis. Now they’re monitoring wear and tear on the road to see if it performs as well as conventional pavement.”
Schideman acknowledges that while they are making important advances in their research, there is also a need to expand collaborations and noted work with other researchers at the Illinois Sustainable Technology Center and the Department of Civil and Environmental Engineering. “There is still significant work that needs to be done in order to better understand the bio-oil products and their potential use in different applications. We look forward to working with others to accelerate the development of bio-oil products that can provide sustainable alternatives to petroleum.”