垃圾焚烧飞灰与果蔬垃圾发酵残渣协同处置及深度脱氯机理研究

At present, the method of remove chlorine by water leaching from the municipal solid waste incineration fly ash can not effectively remove the insoluble chlorine, so it is difficult to improve the mixing ratio of fly ash in the raw material of the cement kilns. While markets produce a large amount of fruit and vegetable wastes, large numbers of residues and waste liquid was formed by fermentation of lactic acid or hydrolysis acidification (first stage of methane fermentation), high costs of the treatment created. This project adopts fermentation residues of fruit and vegetable waste which containing a large number of indigenous bacteria (lactic acid bacteria, hydrolytic acidification bacteria, etc.) mixed with fly ash, use high concentration liquid of fermentation residue instead of water for leaching, constructed a new pattern for deep dechlorination with synergistic disposal of fly ash and waste fermentation residues, clarified the bioleaching mechanism of the insoluble chlorine (CaO▪Al2O3▪CaCl2▪10H2O and AlOCl); study on the characteristics of indigenous bacteria in fermentation residues, screen and domesticate excellent strains as exotic bacteria, study on the mechanism and interection between the indigenous and exotic bacteria to accelerate the deep dechlorination of fly ash, expound the evolutionary changes of microbial colony in the process of dechlorination; systematically assessed the environmental safety and technical economy of fly ash instead of building materials after deep dechlorination and fermentation residues to replace part of fuel, achieved the concept of disposal waste with waste, provide scientific basis for utilization and synergistic disposal of fly ash and fermentation residue.

目前生活垃圾焚烧飞灰水洗脱氯的方法不能去除不可溶氯，故难以提高飞灰在水泥窑入窑原料中的掺入比，其它建材利用也受到限制；而农贸市场大量产生的果蔬垃圾，在乳酸发酵、水解酸化（甲烷发酵前的酸化阶段）并提取目标产物后剩下大量残渣和残液，其处理成本较高。本项目以含大量土著菌（乳酸菌、水解酸化菌等）的果蔬垃圾发酵残渣与焚烧飞灰混合，以含高浓度有机酸的发酵残液代替水淋洗飞灰，构建飞灰和发酵残渣协同处置的深度脱氯新模式，阐明飞灰中不可溶氯（CaO•Al2O3•CaCl2•10H2O和AlOCl等）的生物浸出机理;筛选和驯化性能优良的功能菌株作为外来添加菌，探讨土著菌和添加菌协同加速飞灰深度脱氯的机制和影响规律，特别是细菌（如硅酸盐菌）和真菌（如黑曲霉菌）的相互作用机理，阐明飞灰脱氯过程中微生物群落演替规律；探讨飞灰深度脱氯与有机物降解的相关性，为实现以废治废、飞灰和发酵残渣协同处置及资源化提供科学依据。

生活垃圾焚烧飞灰中高含量的重金属和氯是其资源化（如水泥窑协同处置）的限制性因素。鉴于此，本项目以含大量土著菌（乳酸菌、水解酸化菌等）的果蔬垃圾发酵残渣与焚烧飞灰混合，构建飞灰和发酵残渣协同处置的深度脱氯新模式。该工艺可提高飞灰入水泥窑的掺入比例，为实现以废治废、飞灰和发酵残渣协同处置及资源化提供科学依据。. 本研究的果蔬垃圾乳酸发酵液酸洗飞灰静态浸出实验结果表明，乳酸发酵液的投加方式不同，其飞灰脱氯除重金属的效果显著不同。其中，两步加酸的静态浸出方式（即三步洗灰实验中，第一步用水洗，第二步和第三步用乳酸发酵液酸洗）脱氯效果最好，该方式可脱除飞灰中98.7%的总氯和95.6%的水不可溶氯。进一步采用果蔬垃圾发酵残渣与焚烧飞灰共填埋的方式，考察动态淋滤时飞灰的脱氯效果。结果表明，当果蔬垃圾发酵残渣与焚烧飞灰以2:1的比例共填埋，并接种厌氧污泥时处理效果最佳。共填埋的处理方式可使飞灰入窑掺入比最高可比飞灰单独填埋提高11.3个百分点，同时最高可实现72.1%的节水率。此外，硅酸盐细菌-黑曲霉脱氯体系的飞灰生物脱氯新工艺也可在一定程度上提高飞灰的脱氯量。. 静态浸出实验明确了乳酸发酵液去除飞灰中不可溶氯的机理，即乳酸发酵液中的H+可破坏飞灰颗粒结构，使存在于飞灰颗粒内部的氯离子释放；且飞灰中AlOCl等不可溶氯可在H+作用下被酸离解而脱除；此外，发酵液中大量乳酸根离子及少量CO32-和SO42-离子可与飞灰中的氯盐（如Ca(OH)Cl）发生置换反应生成钙盐沉淀而起到脱氯保钙作用。. 此外，乳酸发酵液酸洗飞灰在脱氯的同时还可去除飞灰中的重金属，飞灰中重金属的总浸出量随乳酸发酵液添加量的增加而增加，其浸出量比水洗提高至少112.5 %；按氯为限值的飞灰入窑比计算，酸洗后入窑飞灰中Cd和Pb含量分别为9.7 mg/kg和102.2 mg/kg，远低于入窑标准的限值，从而明确了限制入窑飞灰掺入量的关键因子是氯含量而不是重金属含量。本项目研究结果对解决飞灰的污染问题、实现飞灰深度脱氯、全面推进飞灰资源化进程具有重要意义。