Characteristics of Greenhouse Gas Emissions with Different Combination Rates of Activated Rice Hull Biochar during Aerobic Digestion of Cow Manure

Abstract

BACKGROUND: Among the biomass conversion techniques of livestock manure, composting process is a method of decomposing organic matter through microorganisms, and converting it into fertilizer in soil. The aerobic composting process is capable of treating cow manure in large quantities, and produces greenhouse gas as CO 2 and N 2 O, although it has economical benefit. By using the activated rice hull biochar, which is a porous material, it was intended to mitigate the greenhouse gas emissions, and to produce the compost of which quality was high. Objective of this experiment was to estimate CO 2 and N 2 O emissions through composting process of cow manure with different cooperated biochar contents. METHODS AND RESULTS: The treatments of activated rice hull biochar were set at 0%, 5%, 10% and 15%, respectively, during composting cow manure. The CO 2 emission in the control was 534.7 L kg-1 , but was 385.5 L kg-1 at 15% activated rice hull biochar. Reduction efficiency of CO 2 emission was estimated to be 28%. N 2 O emission was 0.28 L kg-1 in the control, but was 0.03 L min-1 at 15% of activated rice hull biochar, estimating about 89% reduction efficiency. CONCLUSION: Greenhouse gas emissions during the composting process of cow manure can be reduced by mixing with 15% of activated rice hull biochar for eco-friendly compost production.