冷凝水回流对堆肥腐熟度和污染气体排放影响

为探究堆肥过程中高温水蒸气携带的冷凝水回流对腐熟度及温室气体排放的影响,本文以猪粪和厨余垃圾为堆肥原料,在60L密闭好氧堆肥反应器中进行48d的高温好氧堆肥实验.结果表明,堆肥高温期产生的饱和水蒸汽因发酵罐封闭体系不能及时排出,会在发酵罐壁形成冷凝水回流入堆体中,整个堆肥过程冷凝水产率为物料湿重的18%.此外,回流冷凝水中主要成分为NH₄⁺-N(11.40g/L)、溶解性有机碳(6.3g/L)以及无机盐离子,具有较高的EC值(41.05mS/cm)和pH值(9.22),而较高的NH₄⁺-N含量使冷凝水回流处理的堆肥产品种子发芽指数(GI)略达到腐熟(71.4%),与排出处理相比GI下降了25.5%.同时,冷凝水回流使NH₃和CH₄排放量分别增加了55.2%的60.2%,但是CO₂和N₂O排放量分别降低了16.8%的34.8%.研究表明,冷凝水回流可降低17.8%总温室效应.本文建议堆肥过程将高温水蒸气冷凝排出,一...

Effect of condensed water reflux on maturity and greenhouse gas emissions during composting

In order to investigate the influence of condensed water reflux on maturity and greenhouse gas emissions during composting, the trial was conducted with pig manure and kitchen waste in a 60L reactor for 48 days. The results showed that the saturated steam produced during thermophilic composting could not be emitted due to the closed system of reactor and transformed into condensed water, accounting for 18% of the wet weight of raw metarials. In addition, the main components of the condensed water were ammonium nitrogen (NH₄⁺-N, 11.4g/L), dissolved total organic carbon (TOC, 6.3g/L) and inorganic salt ions, resulting a higher EC (41.05mS/cm) and pH (9.22). However, due to its higher NH₄⁺-N concentration of the condensed water, the seed germination index (GI) in the condensed water reflux treatment had a lower maturity (71.4%), which decreased by 25.47% comparing with non-reflux. Furthermore, condensate reflux increased NH₃ and CH₄ emissions by 55.17% and 60.24%, but CO₂ and N₂O emissions decreased by 16.77% and 34.76%, respectively. Overall, condensate reflux reduced the total greenhouse gas emission by 17.8%. On the whole, we suggested the saturated steam should be condensed and discharged during composting, which could improve maturity and reduce moisture content of final compost, and decreasing the NH₃ emissions. Further, if the condensed water can be collected, the nitrogen element will be recycled and reused. This paper provids theoretical basis and data support for the water removal and maturity in closed aerobic composting system.