The unique properties of biochars make them widely researched and applicable in agriculture field including improvements in soil physical, chemistry and biology characteristics and crop productivity. In this paper, we would like to present new perspectives for the utilization of biochar in renewable methane production and organic fertilizer production. We recently developed an integrated waste-to-energy-nutrient recycle system (IWENRS) for utilization of agricultural wastes such as manure and biochar1. Anaerobic digestion of organic wastes with biochar resulted in pipeline quality renewable methane (&gt;90% methane) and high fertilizer value digestate (aka left over from anaerobic digestion of organic waste). We successfully scaled up process from bench-scale digesters (0.5 liter) to pilot-scale digesters (200 gal) located in a swine farm. It was also important to understand how biochar supplemented digestate application rates impact nutrient dynamics in harvested crops, which ultimately affects sustainability of IWENRS. After 32 weeks of cultivation period in greenhouse, switchgrass treated with digestate + biochar resulted in increased biomass yield and comparable feedstock composition. Results showed that digestate supplemented with biochar has a potential to substitute chemical fertilizer because of high concentrations of N, P, K, Ca, Mg, Fe and S. The optimal digestate application rate was estimated 90 kg total-N ha-1for the switchgrass cultivation. In summary, the environmental improvement provided by this technology would be in six major areas: a) Reduce disposed manure and secondary lignocellulosic waste volume at the farm, b) Reduce groundwater and surface water contamination, c) Capture nutrients for reuse & reduce use of inorganic fertilizers when the digesters solids applied to soil for crop production, d) Less uncontrolled methane emissions from feedlots, e) Produce renewable methane which has a low greenhouse gas (GHG) footprint, f) Replacement of fossil fuels with renewable methane derived from manure and other organic waste streams. Taken together the process could enhance the economics of AD to make high-quality renewable methane and high fertilizer value digestate that can be used for on-site power generation in the farms and cultivation of crops, respectively. This is important in rural areas where access to natural pipelines is limited and propane utilization is high, hence costly.

New perspectives for biochar utilization under food-water-energy nexus

255th National Meeting (2018)

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