通风速率对市政污泥好氧堆肥氮素转化的影响

Effect of Ventilation Rate on Nitrogen Transformation of Municipal Sludge in Aerobic Composting

堆肥过程中氮素的转化对堆肥产品的肥效有着重要影响。以市政污泥和蘑菇渣为原料,按照湿质量比1∶0.7混合后进行为期26 d的好氧堆肥,设置3个不同通风速率的堆体A[2.4 m3/(m3·h)]、B[2.9 m3(/m3·h)]、C[3.3 m3(/m3·h)],考察通风速率对堆肥过程中含氮有机物转化及NH3挥发的影响。结果表明,堆肥完成后A、B、C堆体的总氮损失率介于16.90%~25.10%之间,NH3挥发占总氮损失的比例介于68.49%~72.97%之间。B堆体通风速率下NH4+-N向NO3--N转化更多,B堆体NO3--N含量较A和C堆体分别增加了30.31%和8.98%。结构方程模型显示,不同通风速率下,酸解氨态氮(AN)最易转化为NH4+-N,通风速率为2.9 m3/(m3·h)时微生物代谢活跃,促进了氨基糖态氮(ASN)的积累,且NH4+-N转化为难以矿化的酸解未知态氮(HUN),增加了对氮素的固定。兼顾腐熟条件和氮素损失,通风速率以2.9 m3(/m3·h)为宜。

The transformation of nitrogen in composting process has an important impact on the fertilizer efficiency of composting products.Municipal sludge and mushroom residue were mixed with the wet weight ratio of 1∶0.7 and then aerobic composted for 26 days.Three piles with different ventilation rates,namely pile A[2.4 m3/(m3·h)],pile B[2.9 m3/(m3·h)]and pile C[3.3 m3/(m3·h)],were set to investigate the effect of ventilation rate on the transformation of nitrogen‑containing organic matter and NH3 volatilization during composting.After composting,the total nitrogen loss rate of the 3 piles(A,B and C)ranged from 16.90%to 25.10%,and the proportion of NH3 volatilization in total nitrogen loss ranged from 68.49%to 72.97%.In pile B,more NH4+-N was transformed into NO3--N,and the NO3--N of pile B was increased by 30.31%and 8.98%compared with that of pile A and pile C,respectively.The structural equation model showed that amine nitrogen(AN)was most easily transformed into NH4+-N under different ventilation rates.When the ventilation rate was 2.9 m3/(m3·h),the microorganism was more active,which promoted the accumulation of amino sugar nitrogen(ASN).In addition,NH4+-N was transformed into non‑biodegradable hydrolysable unknown nitrogen(HUN),which increased the fixation of nitrogen.Considering both maturity conditions and nitrogen loss,the optimum ventilation rate was 2.9 m3/(m3·h).