摘要
采用浸没式燃烧工艺产生的生活垃圾填埋场浓缩液污泥具有极高易溶盐含量的特征。水泥对其固化成本高且效果不理想。以矿粉和垃圾焚烧飞灰为前驱体,NaOH和Na_(2)SiO_(3)溶液为碱激发剂制备地聚物胶凝材料,用于固化浓缩液污泥。对固化污泥进行一系列无侧限抗压强度试验,浸泡试验以及矿物成分物相转换,热稳定性和微观结构分析,探索碱激发矿粉/飞灰胶凝材料对浓缩液污泥的固化效果和固化机理。试验结果表明:碱激发矿粉/飞灰胶凝材料可高效环保地对浓缩液污泥进行有效固化。固化污泥的28d无侧限抗压强度随矿粉掺量的增加而增加,飞灰可有效促进前驱体的聚合反应,提高固化污泥的抗压强度和水稳定性;相应于矿粉掺量为10%,20%,30%和40%时,复掺30%飞灰的固化污泥的28d无侧限抗压强度分别增加31%、157%、62%和36%。以20%以上矿粉和30%飞灰为前驱体的地聚物固化污泥可满足填埋场的填埋强度,水稳定性和浸出毒性要求。以40%矿粉和30%飞灰为前驱体的地聚物固化污泥的28d无侧限抗压强度超过25MPa,远大于相同掺量水泥和飞灰的固化污泥。碱激发矿粉/飞灰胶凝材料固化浓缩液污泥的微观固化机制可解释为:矿粉/飞灰前驱体在碱激发条件下生成三维网状地聚物胶凝材料,可对浓缩液污泥实现有效的胶结和包裹。采用飞灰作为矿粉的部分替代品可有效地实现有害废物资源化和矿粉消耗减量化的节能环保目的,达到飞灰与浓缩液污泥的危废/固废“共处理”目标。
The concentrated solution sludge(CSS)produced by the immersion combustion evaporation process has extremely high soluble salt content.The cost of cement as curing agent is high and the solidification effect is poor.Ground granulated blast-furnace slag(GGBS)and municipal solid waste incineration(MSWI)fly ash were used as alkali-activated precursors,NaOH and Na_(2)SiO_(3)solutions as alkali activators to prepare geopolymer for solidification of CSS.A series of unconfined compressive strength(UCS)tests,water immersion tests and microscopic observation tests were carried out on the solidified sludge to investigate the solidification mechanism.Results show that:the 28d UCS of the solidified CSS increases with an increase in GGBS content,the MSWI fly ash can effectively promot the geopolymerization of the precursors and improve the compressive strength and water stability of the solidified sludge;the 28d UCS of the CSS solidified by GGBS geopolymer collaborating MSWI fly ash increases by 31%,157%,62%and 36%compared with that of the CSS solidified by GGBS geopolymer with 10%,20%,30%and 40%GGBS content,respectively.The CSS solidified by the geopolymer with 20%GGBS content and 30%MSWI fly ash content is capable of satisfying the requirements of landfill strength,water stability and leaching toxicity.The 28d UCS of the CSS solidified by the geopolymer with 40%GGBS content and 30%MSWI fly ash content exceeds 25 MPa.The microscopic observation shows that the three-dimensional and network-like geopolymeric generated by alkali-activated GGBS and MSWI fly ash can effectively cement and encapsulate the CSS particles,which is the solidification mechanism of the CSS solidified by the GGBS and MSWI fly ash geopolymer.The utilization of MSWI fly ash as a partial substitute for GGBS can help to realize the energy conservation and environment protection purposes of hazardous waste reclamation and GGBS consumption reduction,and hit the target of co-disposal of hazardous/solid waste of the MSWI fly ash and CSS.
作者
梁仕华
王杰
王羽心
齐添
冯德銮
Liang Shihua;Wang Jie;Wang Yuxin;Qi Tian;Feng Deluan(Guangdong University of Technology,Guangzhou 510006,China;Guangzhou Environmental Protection Investment Group Co.,Ltd.,Guangzhou 510000)
出处
《土木工程学报》
EI
CSCD
北大核心
2023年第S01期75-89,共15页
China Civil Engineering Journal
基金
国家自然科学基金(No.52078142)
广州市科技计划项目(No.202002030194)
关键词
浓缩液污泥
碱激发胶凝材料
垃圾焚烧飞灰
物相转换
固化机理
concentrated solution sludge
alkali-activated cementitious materials
MSWI fly ash
phase transition
solidification mechanism
