摘要
采用强制通风静态垛和温度反馈自动测控堆肥工艺 ,研究了鼓风过程对城市污泥好氧堆肥温度的影响。当城市污泥和调理剂比例为 1∶ 1时 (体积比 ) ,处于鼓风口远端 (风向远点 )各个层次的堆体温度基本上不会随鼓风过程而变化 ;处于鼓风方向中部 (风向中点 )、鼓风口近端 (风向近点 )的堆体 ,其中层、上层的温度将会下降 ,平均下降速率分别为0 .0 5℃ / min、0 .0 4℃ / min,但是温度下降的速率在整个鼓风过程中并不均匀 ,温度下降速率在 0～ 1 0 min较快 ,在 1 0～4 0 min较慢 ;当混合堆料中调理剂含量较低时 ( 3∶ 2 ) ,堆体上层温度在鼓风过程中将会上升 ,上升速率约为 0 .0 2 2～0 .0 5℃ / min,中层温度下降 ,在鼓风开始阶段 ( 0～ 1 0 min) ,下降速率较快 ,约为 0 .1 2℃ / min,随后变化速率较小 ,约为0 .0 1℃ / min。对于不同调理剂比例的堆体 ,处于风向远点、中点的下层温度基本不受鼓风作用的影响 ;处于风向近点的堆体 ,其下层温度会随着鼓风过程而下降 ,平均下降速率约为 0 .0 2 5～ 0 .0 3℃ / min。
It was well recognized that many factors affected the composting process and the resulting product, and temperature was the most important ecological determinant for composing material. The achievement of minimum temperature layers was important to an effective composting process and contributed substantially to the high rates of decomposition achieved during processing. As the composting began, temperature increase occurred throughout the pile and the well insulated regions of the inner zones of the pile passed through the mesophilic/ thermophilic boundary, which was in the range of 44℃ to 52℃. High temperatures (e. g 55℃) had been proved to eliminate potential pathogenic microorganisms in the compost substrate. Heat generation was proportional to the volume of the pile and heat loss was proportional to the surface area of the compost pile. The larger the pile, the less heat loss and the greater the temperature.Temperatures above 60℃ began to impact on the activity of the microbial community. Ultimately, the temperature might reach above 80℃ at which stage the biological community was severely destroyed. The optimum composting temperatures, based on the most efficient decomposition, were in the range of 52℃ to 60℃. The temperature of a pile depended largely on airflow. The temperature between the center and the surface of the pile varied greatly in static piles largely because of airflow. Turning of stacks or forced aeration, as in environmentally controlled composting, could control temperature effectively. Termination of such practices resulted in the temperature soon returning to the range of 70℃ to 80℃. So airflow process was important to control the composting temperature. The aims of this study were to investigate: (i) How did aerating process influence the composting temperature in the aerated static pile system? (ii) to what degree aerating process influenced the composting temperature?Two aerated static piles were designed in a building in two 1.6m×1.0m bays with cement floors and walls. Aeration boards were laid on the bottom of the bays. The piles contained sewage sludge (dry matter=15.1 percent) and bulking agent with two proportions: 1∶1 (Mix 1) and 3∶2 (Mix 2) by volume. A bulking agent layer on the aeration boards dispersed air through the 1.0 m high mix layer. Two piles were covered with a 20 cm insulating layer of recycled compost. Each bay had a aerator to supply ambient air. Sensors were inserted into the different positions of the piles to detect the composting temperatures, and the detected data was fed back to the computerized control system. A three-stage control algorithm controlled the damper duty cycle of aerators. The primary composting process had been undertaken for 16 days. When the composting process was during the high temperature period (>55℃), the aerating process kept for 40 minutes, and a computer with a automatic control software (Compsoft) logged temperatures of all positions every 5 minutes and generated reports.The varying pattern and degree of temperature were different when mixing ratio of feedstock and monitored spots were different. The monitored spots were located at upper layer、middle layer and under layer of piles following to the aerating direction. When the mixing ratio of sewage sludge and bulking agent was 1:1, the temperature decreasing speed of middle-layer and upper-layer located at middle position and upper position following to the aerating direction was about 0.04~0.05℃/min. When the mixing ratio was 3∶2, the temperature of upper-layer increased at the speed of 0.022~0.05℃/min. The temperature of middle-layer decreased at the speed of 0.12℃/min in the early stage of aerating (0~10mins), then at the speed of 0.01℃/min during the period of 10~40mins. The temperature of under layer located at middle position and backward position was not influenced by aerating, but the under layer temperature of upper position decreased at the speed of 0.025~0.03℃/min.
出处
《生态学报》
CAS
CSCD
北大核心
2002年第5期742-746,共5页
Acta Ecologica Sinica
基金
国家"九五"科技攻关资助项目 ( 96 -90 9-0 1 -0 5 )
北京中科博联环保高新技术有限公司资助项目
关键词
鼓风
城市污泥
好氧堆肥温度
静态垛
sewage sludge
composting
static pile
temperature
aerating
