人粪便好氧堆肥温度对氮迁移转化的影响

EFFECT OF TEMPERATURE ON THE TRANSFORMATION OF NITROGEN IN AEROBIC COMPOSTING PROCESS FOR HUMAN FECES DISPOSAL

利用密闭式好氧堆肥反应器,以新鲜锯末为空白载体,通过批量实验,研究了堆肥温度对人粪便降解效果的影响,尤其是在堆肥过程中氮的迁移转化特性.结果表明,在60℃的高温堆肥条件下,粪便中有机物(化学需氧量COD、总有机碳TOC、有机固体Sorg)的去除率可达70%以上,而35℃的中温条件下的有机物去除率为63%;高温堆肥的腐熟期可从中温条件下的10—11 d缩短到6—8 d.高温条件下粪便中的氮具有良好的保持特性,总氮Ntot的损失仅为17%,远低于中温条件下31.4%的总氮损失.考察堆肥反应过程中氮的形态变化,发现高温条件下氮的损失仅发生在堆肥反应的第一天,且表现为无机氮Nino(主要为铵态氮NH+4-N)迅速转化为氨气释放,而有机氮Norg含量保持不变.与此相比,中温条件下氮的损失可持续4 d,且伴随着部分Norg向NH+4-N和氨气的转化,导致氮的损失增大.氨气吸收和物料衡算的结果表明,每种温度下Ntot的减少量与通过氨气释放的氮的总量相等,说明NH4+-N挥发为氨气是堆肥过程中氮损失的主要原因.60℃的高温堆肥不仅可以加快有机物的腐熟,提高堆肥效率,还能有效减少氮的损失,提高产物的肥效.

Batch experiments were conducted using a closed aerobic composting reactor with sawdust as the bulky matrix for the disposal of human feces.Attention was paid to the characteristics of transformation of nitrogen under two typical temperatures.As a result,more than 70% fecal organics were decomposed at 60 ℃ in a two-week composting period,while 63% organics were decomposed at 35 ℃.The maturation period of the composts decreased from 10—11 days at 35 ℃ to 6—8 days at 60 ℃.High temperature composting showed a better nitrogen holding property in the compost,for the total nitrogen loss was found to be only 17% at 60 ℃ versus 31.4% at 35 ℃.At 60 ℃,the nitrogen loss happened on the first day of composting with the generation of ammonia gas from the inorganic nitrogen only（ammonium as the main component）.In contrast,at 35 ℃,nitrogen loss continued for about 4 days with partial transformation of organic nitrogen into ammonium and then the emission of gaseous ammonia.By quantitative measurement of the adsorbed gaseous ammonia and mass balance calculation,it was found that the quantity of the emitted gaseous ammonia equaled to the quantity of the total nitrogen loss,indicating that gaseous ammonia generation was the main reason for nitrogen loss in the composting process.Aerobic composting at 60℃ would be a suitable operation condition for shortening the maturation period of the compost,increasing the efficiency of composting operation,decreasing nitrogen loss,and increasing the fertilizing effect of the composting product.