Ammonium Pretreatment and Addition Improve Stability of Environmental Parameters and Biogas Production under Anaerobic Co-digestion of Rice Straw and Dairy Manure

Abstract

This paper optimized the anaerobic digestion (AD) pretreatment process, identified the relationship between stability of environmental factors and biogas production under ammonium hydroxide (NH3{middle dot}H2O) pretreatment and analyzed the reason of NH3{middle dot}H2O pretreatment to increase biogas production. Variable coefficients (CVs) of environmental factors were calculated to study the stability of environmental factors during AD process. The effect of initial AD environment factors on the stability of environmental factors during AD process was analyzed by redundancy analysis. Path analysis was used to analyze the response relationship the stability of environmental factors between and total biogas production (TBP). Results showed that pretreatment at 8% for 4 days, the TBP produced the highest value (302.5mL/g TS) and significantly higher than the other values (P < 0.01). NH3{middle dot}H2O pretreatment had effect on the initial AD environment factors and the environment factors during AD process. Under the NH3{middle dot}H2O pretreatment conditions, the stability of environment factors during AD process was affected by initial AD environment factors, while they had direct and indirect influences on the TBP. This research concluded that NH3{middle dot}H2O pretreatment improved TBP via changing the initial environment of AD and the stability of environment factors during AD process, as well as the response relationship among initial AD environment factors and the stability of environment factors during AD process and biogas production, the changes improved the stability of environmental factors and made the environment more suitable for AD.