Enhanced Removal | 高效去除剂
organic sulfides | 有机硫化物
SOLUBILITY OF METAL | 金属的可溶性
Hydroxide/Sulfide vs. | 氢氧化物/ 硫化物对pH|
102
101
Pb(OH)2
Zn(OH)2
Solubility of Metal (mg/l)
METALS REMOVAL 重金属去除剂
Why Remove Metals? 为什麽要去除重金属?
Environment | 环境 Biological Treatment Units | 生物处理单元 Metals Recycled within a Plant | 工厂回收利
用重金属
Coagulation | 混凝 alum / ferric / polymer | 铝盐 /铁盐 /聚合物
Flocculation | 絮凝
Precipitation is a Function of... | 沉 淀和…相关
Ksp | Ksp Time | 时间 pH | pH Presence of Complexing/Chelating
Agents | 络合剂/螯合剂的浓度
Solubility of Metal (mg/l) 金属的溶解度 (毫克/l)
SOLUBILITY OF METAL | 金属溶解度 Hydroxide vs. PH| 氢氧化物vs. pH
10
1.0
Zinc | 锌
0.1 0.01 0.001
Chromium | 铬 Nickel | 镍 Copper | 铜
混合池
.. . .. . . .Flo.c .TK. . . . . ..
絮凝池
.... C. l.a.r.if.i..er...
澄清池
Hydroxide Precipitation 氢氧化物沉淀法
Caustic, Lime, or Soda Ash | 碱，石灰或 氢氧化钠
Polyvalent Heavy Metals are Amphoteric | 多价的重金属是两性的
再溶解
Cons | 缺陷
Excess of Sulfides usually required - post treatment necessary | 硫化物通常需要过量 – 需后续处理
Sulfides cost more than alkalis used in hydroxide | 硫化物用量超过碱用量
6
789
10
11 12
pH of solution | 溶液 pH
Coagulating Agent|混凝剂
Lime石灰
like PAC
Metal Containing
Waste 含重金属
废水
.. . .. . .. .. ..M....I.X.. .T...A.N...K.
Flocculating Agent絮凝剂 PAM
Metal Containing
Waste 废水
.. . .. . .. ..
. ..
..M... IX...
T. ..K..
.
混合池
... F. lo.c T. K
. .. .. .. 絮凝池
Metal Containing
Waste 废水
.. . .. . .. .. ... ..M... IX... .T..K.. ..
Metals Removal Processes 重金属去除方法
Aeration / Sedimentation | 曝气 /沉淀 Precipitation (pH adjustment) | 沉淀 (调整pH)
Hydroxide (Lime/Caustic) | 碱(石灰/碱) Sulfide | 硫化物 Co-precipitation (Iron or Aluminum Salts) | 共沉淀 (加 入铁或铝盐) Sedimentation/Filtration | 沉淀/过滤 Activated Carbon | 活性炭 Ion-Exchange | 离子交换 Activated Sludge Biological Treatment | 活性污泥
Organic Sulfide may be sufficent at low metal concentrations | 有机硫化物在较低金属浓度时比较有 效
Examples of Pretreatment for Stabilized Metals 预处理
Ammonia - remove via chlorination, stripping, or biological treatment | 氨 - 由氯化，吹脱或生物法去除
0.1 0.01 0.001
Chromium | 铬 Nickel | 镍 Copper | 铜
6
789
10
11 12 |
pH of solution | 溶液 pH
Interferences of Metals Removal 重金属去除的影响
Complexing / Chelating Agents | 络合剂/鳌合 剂
What’s the Same - What’s Different 什么是相同的 - 什么是不同的
Mechanisms are Similar | 机理是相似的
Mixtures of Metals | 金属的混合
Multistage pH Adjustment and Clarification | 多节的 pH 调整和澄清
Single Step - find one pH to give satisfactory results- if possible 单一步骤 - 找 一个合适的pH达到满意的结 果
| 金属的可溶性 (毫克/l)
100 10-1
10-2 10-3 10-4 10-5 10-6
6
Cd(OH)2 Cu(OH)2
PbS
CdS
ZnS
7 8 9 10 11 12 pH of solution | 溶液 pH
Sulfide Salts
(Sodium sulfate, ferrous sulfide, and calcium polysulfide)
Precipitation through pH adjustment PH 调节沉淀法
Hydroxide Precipitation | 生成氢氧化物沉淀 and then | 然後
Removal of Precipitate via gravitational | settling or filtration. |
Cd2+
Al3+
Cr+3,6 Cu2+ Hg+0,1,2
Mn2+,4
M+M+ | MM++
M+ | M+
M+
M+
M+ M+ | M+
M+ | M+MM+ + | M+
M+ | M+M+ M+ | M+
Pb2+ Zn2+ Ni2+
M+ = Insoluble Metals in the form of MOH or MS = 不能溶解的金属以 MOH 的形式或 MS
Metals Contaminant Treatment 重金属污染物的去除
Prevent Formation in the First Place 首先要避免形成
Corrosion Control Condensate Systems | 控制浓缩 系统的腐蚀
Minimize Catalyst Fine Carryover | 将催化剂细粉的 流失减到最少
EDTA, tartarate, ethylenediamine, gluconate, or pyrophosphate, cyanide, ammonia | EDTA ， 酒石 酸，乙二胺，葡萄糖酸盐或焦磷酸盐， 氰化物,氨
Treatment - Chemical Reduction or pH adjustments | 处理 – 加药或 pH 调整
unreachable by conventional precipitation alone | 只用普通的沉淀法就可以将金属浓度降到以前无法达到 的较低浓度 Works on: | 用途：
Best: Cd, Cr, Cu, Pb, Hg, Ni, Zn | 最佳 Next Best: Al, Co, Fe, Mn, Ag, Sn, Va |良好
Eliminate Metal-containing Treatment Chemicals |
避免使用含金属的化学药品
Compensate for Presence of Metals | 重金属出现 后的补救措施
Dispersants | 分散剂
METALS ARE SOLUBLE and INSOLUBLE 金属是溶解的和不能溶解的
Cyanide - remove via chlorination or oxidation on Activated Carbon | 氰化物-由刺激的碳上氯化或氧化除 去
Chelant - Excess Chemical Precipitant or Acid Addition (to pH of 2-4) | 鳌合剂- 投加过量化学品沉淀 或加酸调节PH到 2-4