【作者】 章金骏；

【导师】 翁焕新；

【作者基本信息】 浙江大学 ， 环境科学， 2012， 博士

【摘要】 污泥是一种产生于污水处理过程的对人体和环境有很大危害的固体废弃物,随着我国城市化进程的加快,污泥产生量越来越大。其含水率高、体积大,力学性质差,给堆放和运输带来困难,且污泥中含有大量的有毒物质,如果不能妥善地处理处置,将会带来严重的环境问题。目前成熟的污泥处理方法有：卫生填埋、土地利用、干化和焚烧等,几种方法各有缺点,研究新的污泥处理技术很有必要。本文通过对污泥物理化学性质的分析,结合粘土陶粒烧制工艺,分析了污泥掺加不同比例粘土、粉煤灰烧制陶粒的可能性,研究了污泥在一定条件下烧制轻质陶粒的可行性,建立了一套生活污泥低温干燥后烧制陶粒并最终建材化应用的处置工艺。通过污泥、粘土、粉煤灰的无机成分对比,认为生活污泥具备烧制陶粒的物质基础,并根据SiO2-Al2O3-MgO的热力学平衡系统分析,认为生活污泥掺加一定比率的粘土和粉煤灰后在1100℃-1200℃之间均有可能出现低共熔点。在实验室条件下,模拟工业陶粒生产工艺,采用自行设计的柱状冲压造粒机制备污泥陶粒生料球,通过调节辅料配比尝试将坯料放入烧结炉内用不同温度烧制,待冷却后测试体积、烧失率、堆积密度和表观密度等物理性质分析其烧胀情况,通过比表面积、筒压强度、抗压强度和24h吸水率等性质分析陶粒的建材性能。确认掺加一定比例的粘土在1150℃-1120℃烧制的污泥陶粒均为合格的轻粗集料,具有良好的建材性能,物理性质随着粘土比例的增加而有所变化。其中粘土比例在10-20%,烧制温度为1175℃的陶粒其筒压强度均超过4MPa,比表面积在3m2／g左右,为优良的轻粗集料。而掺加粉煤灰的污泥陶粒在筒压强度等性质上无法达到国家标准,需要继续改进实验方法。根据实验结果结合二段式污泥干化工艺,设计了一套污泥脱水-陶粒烧制-砌块生产的污泥资源化工艺。利用陶粒烧制窑的烟气余热使污泥含水率降至30%后与辅料混合,送入回转窑烧制陶粒,最终制成轻集料砌块。该工艺可充分利用污泥的矿物组分和热值,并能利用烟气余热资源,减少大气热污染,保护环境作用显著。目前建成一条日处理生活污泥20吨,年产污泥陶粒18万m3的生产线,并已投入分段调试阶段,通过估算认为该工程具有良好的经济效益。更多还原

【Abstract】 Sludge generated from wastewater treatment plants represent a potentially harmful solid waste threatens to human health and environment. The amount of sludge is continuously increasing with due to the growth of urbanization in China. Sludge is characterized with high moisture content, huge volume, poor mechanic properties is therefore difficult to be stored and transported. Moreover, combined with a substantial amount of toxic component contains; the sludge poses a threat as a secondary pollution if not handled properly.Nowadays, mature sludge-management method generally contains sanitary landfill, land utilization, drying and combustion. But flows inherently exists limited its application and therefore, it is necessary to deal with through innovative treatment methods. In this article, we assessed the potential of ceramsite produce in sludge mixing with different proportions of clay and coal ashbase while analyzing the fundamental nature of sludge, combine with clay ceramsite sintering process. This method revealed the opportunity of producing light ceramsite under some certain conditions. At last, we established a new municipal sludge treatment characterized with ceramsite sintering after low temperature drying and building material production.Comparing the inorganic components in sludge, clay and coal ash, we concluded that the sludge is qualified as a feed material to produce ceramsite. And we also found that a low eutectic point will likely occurs at 1100℃-1200℃for sludge and clay, as well as for sludge and coal ash mixtures according to thermodynamics balance system of SiO2-Al2O3-MgO.In our laboratorial test, we simulated commercial ceramsite produced from using a self-design columnar stamping granulator to produce sludge ceramsite blank. Some fundamental natures of material, such as volume, ignition loss, bulk density and apparent density were determined to assess the sintering and expanding property. And we also estimated the specific surface area, cylinder compres strength, compressive strength and 24h water absorption to evaluate the potential of ceramsite for building. All the ceramisre used were sintered with modifying ratios of feed mixture and sintering temperature, and all the properties were determined after cooling of ceramsite. The optimum temperature range for sludge ceramsite ranging 1150℃-1175℃, ceramsite produced among this temperature is eligible for building material qualification. The physical characteristics of ceramsite varied with mixture proportion and the ceramsite could be an excellent light aggregate if the mixtures are fired with clay content set at 10-20% of total mixture and temperature set at 1175℃, with cylinder compressive strength large than 4MPa and specific surface area reaching 2m2/g. However, properties of sludge ceramsite produced with coal ash failed to reach the national standard thus it is essential to change the experimental design.Combined two-stage drying process and laboratorial results, we designed a sludge re-using process integrated with the sludge dewatering, ceramsite sintering and block manufacturing. According to our design, the moisture content of sludge was primarily reduced to 30% using flue waste heat from ceramsite production and then mix with auxiliary material. Secondly, the mixture is subject to rotary kiln and burned to produce ceramsite. And the ceramsite is further process into light aggregate block. This process is characterized with the full usage of mineral and heat value of sludge, reducing the influence of atmospheric thermal pollution and also a desirable utilizing of waste heat from flue. At present, the production line with a daily municipal sludge disposal capacity is of 20t and an annually ceramsite production is of 0.18 million m3 and it already began in trial operation. It is estimated that this project will be economically feasible and commercially applicable.更多还原