双碱法降低飞灰渗滤液硬度工艺探究  

Exploration of the Process of Reducing the Hardness of Fly Ash Leachate by Double Alkali Method

作　　者：李金忠 邹笛 方国生 LI Jin-zhong;ZOU Di;FANG Guo-sheng(Welle Environmental Protection Technology Group Co.Ltd.,Changzhou 213100,China)

机构地区：[1]维尔利环保科技集团股份有限公司,江苏常州213000

出　　处：《安徽化工》2023年第6期119-123,127,共6页Anhui Chemical Industry

摘　　要：长沙某大型焚烧厂将生产活动过程中产生的飞灰进行填埋处置,飞灰填埋过程中产生了大量渗滤液需要进行处理。渗滤液采用“化学除硬+单效强制循环MVR机械蒸汽再压缩蒸发结晶+母液干化技术”,连续蒸发浓缩盐水使之结晶后采出固体,凝水可达标排放或返回工艺段回用。尝试探究“化学除硬”段最适的加药量。现场有两股不同硬度的废水(调节池A与调节池B),采用“双碱法”降低原水硬度。实验表明,对于调节池A:500 mL废水投加2.5倍碳酸钠理论量即12.65 mL的30%碳酸钠溶液以及2.8 mL的1 mol/L的氢氧化钠效果较好,总硬度由4050 mg/L降至385 mg/L,去除率约90.49%;对于调节池B:500 mL废水投加2.7倍碳酸钠理论量即13.34 mL的30%碳酸钠溶液以及1.4 mL的1 mol/L的氢氧化钠效果最佳,总硬度由6220 mg/L降至175 mg/L,去除率达到97%。经过化学除硬,调节池A与调节池B废水达到了蒸发工艺段进水的水质要求。A large incineration plant in Changsha landfills the fly ash produced in the process of production activities,and a large amount of leachate is generated in the process to be treated.The leachate adopts the"chemical removal of hard+single effect forced circulation MVR mechanical steam recompression evaporation crystallization+mother liquor drying technology",which continuously evaporates concentrated brine to make it crystallize and produce solids,and the condensate water can be discharged to the standard or returned to the process section for reuse.The experiment try to explore the optimal dosage of"chemical removing hard".In this project,there are two streams of wastewater with different hardness(regulating tank A and regulating tank B),and the"double alkali method"is adopted to reduce the hardness of raw water.The experimental results show that for 500 mL wastewater of regulating tank A,the effect of adding 2.5 times of theoretical amount of sodium carbonate,namely 12.65 mL 30% sodium carbonate solution and 2.8 mL 1 mol/L sodium hydroxide is better,the total hardness is reduced from 4050 mg/L to 385 mg/L,and the removal rate is about 90.49%.For 500 mL wastewater in regulating tank B:adding 2.7 times of the theoretical amount of sodium carbonate,namely 13.34 mL of 30% sodium carbonate solution and 1.4 mL of 1 mol/L sodium hydroxide,has the best effect.The total hardness is reduced from 6220 mg/L to 175 mg/L,and the removal rate reaches 97%.After chemical dehardening,the wastewater of regulating tank A and regulating tank B reaches the water quality requirements of the evaporation process section.

关 键 词：焚烧飞灰 渗滤液 化学除硬 双碱法 

分 类 号：X752[环境科学与工程—环境工程]