通风对餐厨垃圾快速高温堆肥腐熟与氮素转化的影响

针对传统堆肥周期长、脱水效率低、保温效果差等问题,以餐厨垃圾和锯末作为原料,基于外加热源的堆肥反应器,研究不同通风方式(自然通风和外加热源的高温通风)和通风速率对餐厨垃圾高温堆肥过程中温度、含水率、氧气含量、腐熟指标(pH、电导率、发芽指数)以及氮素形态转化的影响。结果表明:1)高温通风有助于堆体维持较高温度,显著延长高温期,提升水分去除率和堆体腐熟度。与自然通风相比,高温通风处理下的高温期(≥50 ℃)延长了6 d,累计温度增加51.77%,水分去除率相对提高了62.37%,种子发芽率相对提高了14.75%;2)高温通风方式会延长高温期进而促进氨排放并抑制硝化作用,造成更多的氮素损失,与自然通风相比,高温通风处理下的氨挥发量相对提高了131.46%,氮素损失相对提高了74.87%;3)通气速率增加可提高堆体的水分去除率,在通气速率达到0.75 L/(kg DM·min)时,水分去除率达到80.31%,除水效果最好;4)高温通风方式下,氨挥发量和氮素损失随着通风速率的增加而增加,其中氨挥发占氮损失的比例为55.48%~70.73%,是氮素损失的主要途径。

EFFECT OF VENTILATION ON DECOMPOSITION AND NITROGEN CONVERSION OF RAPID THERMOPHILIC COMPOSTING OF KITCHEN WASTE

Aiming at the problems of long traditional composting cycle, low dehydration efficiency, and poor insulation preservation effect, this research used kitchen waste and sawdust as raw materials, based on a composting reactor with external heat source, the effect of ventilation modes (natural ventilation and high-temperature ventilation with external heat source) and ventilation rates on temperature, moisture content, oxygen content, maturity index (pH, electric conductivity, germination index) and nitrogen form transformation during high-temperature composting of food waste were studied. The results showed that: 1) the high-temperature ventilation mode was helpful to maintain high temperature of the reactor, significantly prolonged the high temperature period, improved the water removal rate and maturity of the reactor. Compared with natural ventilation, the high temperature period (≥50 ℃) under high temperature ventilation was extended for 6 days, the cumulative temperature increased by 51.77%, the water removal rate increased by 62.37%, and the seed germination rate increased by 14.75%; 2) compared with natural ventilation, the ammonia volatilization and nitrogen loss under high temperature ventilation treatment increased by 131.46% and 74.87% respectively; 3) the increase of ventilation rate could improve the water removal rate. When the aeration rate reached 0.75 L/(kg DM·min), the water removal rate reached the peak value of 80.31%; 4) in the high-temperature ventilation mode, ammonia volatilization and nitrogen loss increased with the increase of ventilation rate, and ammonia volatilization accounted for 55.48%~70.73% of nitrogen loss, which was the main way of nitrogen loss.