湖泊淤泥与生活污泥复合烧结砖的制备、性能及环境安全性

Preparation,properties and environmental safety of fired bricks made from lake silt and sewage sludge

以湖泊淤泥为主要原材料、煤渣为瘠性料、生活污泥为成孔剂,在实验室采用真空挤压塑性成型技术制备并烧结得到烧结砖试样.当湖泊淤泥、煤渣和生活污泥的质量分数分别为85%,10%和5%时,可制备出干燥线性收缩为5.35%、吸水率为16.5%、抗压强度为20.5 M Pa的烧结砖试样.按《环境空气和废气二噁英类的测定同位素稀释高分辨气相色谱-高分辨质谱法》(HJ77.2—2008)的相关规定,采用高分辨气相色谱/高分辨质谱联用仪(HRGC/HRM S)对焙烧过程中产生的气体进行了分析.结果表明,焙烧过程中释放的二噁英毒性当量为0.176 ng TEQ/m3,远低于《生活垃圾焚烧污染控制标准》(GB 18485—2014)中规定的1 ng TEQ/m3排放标准.重金属浸出试验表明,所测重金属浸出浓度低于《危险废物鉴别标准浸出毒性鉴别》(GB 5085.3—2007)限值的5个数量级左右,焙烧过程对重金属进行了有效固化,使用过程中不会造成重金属污染.

A vacuum plastic extruder in laboratory was employed to make the brick samples with lake silt, cinder and sewage sludge as primary raw material, coarse aggregate and poreforming agent. An optimal combination of the linear drying shrinkage （5. 35%）, water absorption （16.5% ） and compressive strength （20. 5 MPa） was achieved for fired bricks made from 85% lake silt, 10% cinder and 5% sewage sludge, respectively. Gases released during sintering process were analyzed by the combined technique of high resolution gas chromatography and high resolution mass spectrometry （HRGC/HRMS） according to the specification HJ 77. 2-2008 （ambient air and flue gas determination of polychlorinated dibenzo-p-dioxins （PCDDs） and polychorinated dibenzofurans （PCDFs） isotope dilution HRGC-HRMS） for testing the PCDDs/PCDFs in environment and waste gas by HRGC/HRMS. The results show that the toxic equivalent of PCDDs/PCDFs is 0. 176 ngTEQ/m^3, which is much less than 1 ngTEQ/m^3, specified in GB 18485-2014 （standard for pol-lution control on the municipal solid waste incineration）. Heavy metal leaching tests show that heavy metals in bricks are lower than that specified in specification for leaching toxicity evaluation of dangerous wastes GB 5085. 3 -2007 （identification standards for hazardous wastes-identification for extraction toxicity） for about 5 orders of magnitudes, demonstrating that heavy metals are effectively immobilized. Thus the environment would not be polluted by the use of the bricks.