新加坡固体废物循环利用于填海造地技术的研究进展

Research Progress of Recycling Singapore Solid Wastes for Land Reclamation

近年来,经济快速发展使得包括新加坡在内的许多沿海国家和地区土地需求量增多,每年的填海规模不断增大,传统的砂石填料已无法满足需求.与此同时,城市固体废物也随着城市化发展而大量产生,其中以生活垃圾焚烧后残留的底渣、海洋淤泥以及建筑工程废土数量尤为庞大.针对世界各国(如丹麦、德国、荷兰等)对固体废物的处置和循环利用以及相关环境标准进行比较说明,并以此为基础介绍采用"化学物理复合法(CPCM)"将新加坡淤泥和垃圾焚烧底渣转化为"淤泥-底渣垃圾材料矩阵(MC-IBA Matrix)"来进行填海造地的"新生土"技术.对化学处理后的新加坡海洋淤泥和生活垃圾焚烧底渣混合物,采用室内三维真空预压和逐级堆载两种不同物理方法来进行加固处理,然后对生成的矩阵材料进行工程测试并依照欧盟与美国的标准进行重金属浸出试验.结果表明:生成的材料矩阵其地基允许承载力在4~6个月内可达15 t/m2,高于一般港口要求(8~12 t/m2).与丹麦No.1662法令和LAGA德国道路工程材料质量标准比较,此材料的重金属浸出值符合其工程材料标准;与荷兰土壤质量法令中工业土壤质量标准相比,此材料符合工业用土标准.工程及环境试验结果均表明了"新生土"作为填海材料的可行性和优越性.从环保角度而言,"新生土"技术中潜在的重金属污染可控,又可缓解日益紧张的填埋场地;从工程角度来看,在较短时间内产生较高地基允许承载力,减少了传统高价砂石的使用,降低工程的时间和成本.因此,对土地有限的国家和地区来说,该绿色技术可解决缺少填埋场用地和填海材料的双重难题.

Recently,due to fast urbanization and economic development,demand on reclaimed land is greatly increased in coastal countries and areas including Singapore. Limited resources of conventional filling materials cannot fulfil such a demand of increasing reclamation projects. Meanwhile,rapid generation of solid wastes has been another great concern,especially incineration bottom ash,marine clay and construction wastes. Solid waste reutilization and relevant reuse standards in different countries,such as Denmark,German,Netherlands and so on,were introduced and compared. Based on these standards,green technology（ ‘New Soil ＇） which transforms the incineration bottom ash（ IBA） and marine clay（ MC） into ‘MC-IBA matrix ＇for land reclamation using ‘ChemicalPhysical Combined Method（ CPCM） ＇has been introduced. Two physical methods,vacuum preloading and surcharge were applied on chemical stabilized MC and IBA mixture for strength improvement. Engineering properties and heavy metal leaching based on European Union and American standards of the resulted MC-IBA matrix were tested. Results showed that,bearing capacity of the resulted matrix can be achieved to 15 t/m2,higher than the normal seaport requirement of 8-12 t/m2; compared with Denmark Statutory Order 1662 and German LAGA standards,heavy metal leaching from matrix material fulfilled the requirements for construction material. Compared with Dutch Soil Quality Decree 2007,the matrix material met industrial soil standard. Engineering and environmental tests proved the feasibility and advantage of using ‘New Soil＇for reclamation. From environmental aspect,‘New Soil＇technology could control potential heavy metal leaching threat and alleviate the high stress on finding landfill space. From engineering aspect,it can achieve high allowable bearingcapacity within short time,reduce use of conventional filling materials and reduce construction cost and time. Therefore,for land-scare countries and areas,the proposed technology is an attractive method which can solve twin problems of limited landfill space and limited resource for reclamation filling materials.