The greenhouse gas emission potential and phytotoxicity of biogas slurry in static storage under different temperatures

With the booming development of biogas industry to treat organic waste in China, the by-product of biogas slurry was accompanied with a huge amount. Static storage process of biogas slurry was normally operated under different seasons before application to land which would cause nutrition decomposition and greenhouse gas emission. Thus, the aim of this study was to investigate the nutrition decomposition, greenhouse gas emission (CH 4 and N 2 O), and phytotoxicity of biogas slurry under different static temperatures, furthermore to illuminate the network among them and functional microorganism. According to the results, higher temperature at 30 °C contributed to fast and complete degradation of COD. In addition, more quantity of NH 4 + conversion and NO 3 − formation appeared at 30 °C. These factors resulted in relatively less crop toxicity together. CH 4 was the dominant greenhouse gas emission than N 2 O and was highest in 30 °C treatment with total emission of 273.7 L/(m 3 ·d) and greenhouse gas emission of 20.01 kg CO 2 e (carbon dioxide equivalent). Lower temperature was conductive to N reservation and reduction of greenhouse gas emission, but making against with stabilization of organic matter and crop safety. At the same dilution times (≤3) of biogas slurry with deionized water, higher temperature at 30 °C could reduce 30 days of storage time, but 10 °C was still unsafe for crop. Structural equation model was further illustrated the positive effect of temperature on NO 3 − , CH 4 , GI, and N 2 O and negative on COD and NH 4 + . These results could help to monitor the environmental risk, evaluate the maturity, guide the irrigation scheme, and regulate the static storage condition of biogas slurry under different seasons.