立式筒仓反应器堆肥技术工艺优化研究

Optimization of composting technology for vertical silo reactor

  • 摘要: 反应器堆肥技术作为一种新型快速堆肥方式逐渐被人们所认可,该技术包括反应器堆肥处理和陈化两个阶段,但反应器堆肥时长和通气方式等工艺参数对堆肥全过程的影响尚不清楚。因此,本研究立足生产中的实际问题,利用12 m3立式堆肥反应器,开展了反应器堆肥工艺优化调控试验,以鸡粪和锯末为原料,分别研究了连续供气和间歇供气(风机开3 min,关7 min)两种供气方式下,反应器处理周期对堆肥有机质降解率、产品含水率、氮素损失和运行成本的影响。研究结果表明:反应器堆肥10 d比2 d的处理物料有机质降解率分别增加60.7%(间歇)和66.2%(连续),产品含水率分别降低41.2%(间歇)和40.7%(连续)。反应器堆肥阶段是物料降解的主要阶段,利用反应器堆肥的时长越长,堆肥产品生产时间越短;但运行成本的增加也对反应器堆肥时长造成了限制,同时增加反应器堆肥时长也会增加堆肥物料的氮素损失,其中连续供气反应器堆肥10 d比2 d氮素损失增加17.5%。连续供气方式可提高堆肥效率,较间歇供气处理堆肥周期平均缩短32.1%,产品全氮含量平均提高7.4%,虽然反应器堆肥阶段每日能耗较间歇供气高20.2%,但堆肥周期的缩短使全程连续供气平均运行成本降低16.5%。其中,连续供气下反应器中处理6 d、8 d和10 d,堆肥产品理化性质无显著差异。综合考虑堆肥效率、产品和经济,本试验建议选择“连续供气方式+反应器内堆肥8 d”处理,既可提高反应器堆肥处理效率,在实际生产中又具有较高的经济效益潜力。

     

    Abstract: Reactor composting technology is a new and quick composting method. The reactor quickly degrades the material and kills pathogens; however, the reactor product is still unable to reach full maturity and requires further curing. The influence of process parameters, such as composting time, reactor discharge aeration mode, maturing treatment, and costs, on the reactor technology is still unclear. To investigate how the composting time and aeration mode affect the reactor efficiency, a pilot composting experiment was performed in a 12 m3 vertical composting reactor with chicken manure and sawdust using continuous and intermittent aeration modes (i.e., gas supply). The composting process was divided into two stages:reactor composting and curing. Five composting times (2, 4, 6, 8, and 10 days) were used in the reactor composting stage, and a static pile turned once per week was used for curing. Samples were taken every 2 days during the reactor composting stage and every 3 days during the curing stage. The temperature, moisture content, total nitrogen, organic matter, and germination index were measured, and the organic matter degradation rate, product moisture content, nitrogen loss, and operating costs were assessed. The results showed that the organic matter degradation rate in the 10-day compost increased by 60.7% (intermittent aeration) and 66.2% (continuous aeration) compared to the 2-day compost, and the product moisture content reduced by 41.2% (intermittent aeration) and 40.7% (continuous aeration). Most of the material degradation occurred during the reactor composting stage, and more time taken during this stage meant that less maturing time was required. However, the cost increased because of high energy consumption and a reduction in the composting reactor capacity. Increasing the reactor composting time also increased nitrogen loss. The 10-day composted material with a continuous gas supply lost 17.5% more nitrogen than the 2-day composted material. Compared with an intermittent gas supply, a continuous gas supply improved the composting efficiency, shortened the composting cycle by 32.1%, and increased the product total nitrogen content by 7.4% on average. The daily energy consumption during the reactor composting stage was 20.2% higher with the continuous gas supply, compared with the intermittent gas supply, but a shorter composting cycle reduced the average operating costs by 16.5%. Based on these results, the "continuous gas supply mode + 8-d in-reactor composting (R8-C)" is recommended to improve the reactor composting efficiency and costs.

     

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