2.1 垃圾覆盖概况 Introduction of Landfill Cover

根据我国《城市生活垃圾卫生填埋技术规范(CH17-2004)》和《生活垃圾卫生填埋场运行管理规范(DB11/T270-2005)》中的要求,在卫生填埋场的设计和运行过程中,垃圾进场后应于24h内完成垃圾的摊铺、压实、覆盖工作。

According to the regulation of "Technical Standard of Urban Domestic Garbage Healthy Disposal" and "Operation Management Standard of Domestic Garbage Healthy Disposal", the healthy disposal designation requires that the garbage has to be spread, compacted, and covered within 24 hours after it entrances landfills.

 

覆盖有以下功能 Basic Functions of Cover:

• 病媒动物的控制Control of Diseases。减少蚊子的栖息场所,并防止固体废物成为滋生各种有害生物的场所。

• 防火Control of fire。防止填埋场堆体中发生火灾,或者降低火势蔓延的可能性。

• 防飞散控制 Control of litters。有助于对轻质垃圾的控制。

• 恶臭控制 Control of Odor。可以成为恶臭的屏障,或者作为过滤器,控制固体垃圾散发恶臭。

• 美化环境 Beauty the Environment。并突出卫生填埋场与垃圾堆的区别。

• 雨污分流 Control of rain。有效降低雨水进入堆体的量,强化雨污分流效果。

 

传统的垃圾覆盖材料: 泥土或油布Conventional Cover Material: Soil or Tarps

目前,在我国绝大部分的垃圾场还在使用20-25cm的压实土壤进行覆盖。使用压实土壤进行填埋场覆盖时,存在以下问题:So far, most of landfills have been still applying soil to cover garbage with a thickness of 20-25cm. The compacted soil cover layer has following deficiencies:

1 泥土:作为填埋场覆盖物会占用大量的库容,从而对填埋场的使用寿命有很大的不利影响。填埋场的本质是对空间的利用,因此必须想方设法研究出空间利用的最大化方案。由于粘土是惰性材料,不会随时间的流逝而降解,因而使用粘土做覆盖材料时,粘土所消耗的空间是无法重新利用的。而从理论上讲,20-25cm的粘土覆盖量将消耗填埋场中大约15%-25%的空间。Soil cover will occupy a lot of space of landfill so that it will reduce the lifetime of landfills. The key point for landfill to save money is to save the available limited space in a landfill. Theoretically, 20-25cm thick soil cover would consume 15-25% space of landfills.

2 泥土: 本身也可能价格不菲,还牵扯到相当数目的间接成本。比如在北京市的安定填埋场,由于场方本身没有现成的土壤进行每日覆盖作业,因此必须从外部购买并引进粘土。而这种运输过程还将增加交通负荷、加速道路与轮胎的磨损、提高燃料消耗并加重了污染物的排放,而且土壤的铺设还要消耗大量的机器和人力等等。The cost of soil and some indirect expenses such as freight and use machines to spread these soil will increase the operation cost of a landfill a lot.

3 泥土: 不利于垃圾的自然降解及渗漏液和沼气的收集,从而间接影响空间的重复利用。因在垃圾堆高后,土壤覆盖层在垃圾内会被压实,加上上层渗入的水份会使这些土壤层形成绝对的不透气层,这个不透气层的坏处是: 阻止微生物降解所需的水份,不利于垃圾的生物降解,从而增加渗漏液处理成本, 不利于垃圾场有效埋空间的回收; 阻止生物气体被气体收集管吸收,且在某些局部产生高压,引起爆炸。The impermeable layer of soil in landfill is adverse for biodegradation of garbage and collection of leachate and biogas, so it will also impact the reuse of landfill space because, after covered by garbage, the soil layers are compacted and become a impermeable layer with the water from top garbage, and the impermeable layer will stop the moisture and leachate used by biodegradation processes to come down andbiogas to be collected.In some cases, the biogas that cannot be collected will lead to pressure accumulation and explosion.

4 油布:也涉及材料和人工管理成本高的问题,因为作为长期覆盖,气体会在油布下面集聚,需增设气体抽吸系统;大面积的覆盖,风对油布的吸力很大,需很多材料来压住;作为日覆盖,每天覆盖和揭开消耗的人力很大,同时也不利于气味的压抑控制。

5 油布:不利于垃圾的自然降解, 因为对雨水的绝对阻隔,不利于垃圾的生物降解所需的一定量的水份, 从而影响垃圾场空间的重复利用。

 

无土覆盖技术 Non Soil Cover Technologies

正因为以上传统的粘土覆盖材料应用技术的这些弊病,国外已基本使用无土覆盖,且越来越多的国内垃圾场也已经启用无土覆盖技术。

无土覆盖就是把一种稠成浆状的物质用喷洒设备喷洒在垃圾或其它物体表面,在迅速的干燥硬化过程中,在垃圾及被覆盖物体的表面形成一个1-3cm厚的保护膜。

Because of these deficiencies,other countries have used non soil cover and more and more landfills in our country start to use non soil cover.

Non soil cover is defined as that a slurry material is spayed on the surface of garbage to form a 1-3cm protection membrane after the moisture is evaporated and the material becomes solid.