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纺织印染工业是我国的传统支柱产业[1]、重要民生产业和创造国际化新优势的产业,在拉动内需、满足人民衣着需求和外贸创汇等方面作出了巨大贡献。然而,纺织工业存在着生产耗水量大、废水排放量大、污染物排放量大和废水处理难度大的四大用水问题[2-5],其产生的具有高色度、高碱度、高COD、高含盐量及含重金属离子等特性的印染废水对于自然环境和人体有着严重危害[6-9],且废水成分复杂、中间产物繁多,包括芳香类化合物、苯胺类、氯化物或溴化物以及多种含有带氢键的物质等[10-13],属于难处理工业废水之一[14]。近年来随着资源利用、节能环保等刚性约束日益增强,国家对纺织印染废水的排放和治理提出了更高的要求。国务院颁布的“水十条”将印染行业列为重点整治行业之一,并提出行业废水需深度处理回用,《印染行业“十四五”发展指导意见》指出要坚持绿色发展,加强污染防治,促进印染行业水重复利用率进一步提高到45%,所以印染废水的中水回用和近零排放具有重要意义。
目前,印染废水通常采用混凝沉淀+水解酸化+生物化学法进行常规处理[15-17],生化出水采用双膜法(膜生物反应器(membrane bioreactor,MBR)/高强度浸没式膜过滤(high-strength submerged membrane filtration,HMF)+反渗透/纳滤(RO/NF))处理工艺[18-20]进行中水回用,对RO/NF浓水处理至纳管达标排放。但将处理后的RO/NF浓水直接排放不仅会带来无机盐资源浪费,还会造成环境破坏[21]。最近研究出的一种小孔径超滤膜能够实现无机盐与有机小分子的高效分离,其孔径介于超滤膜与纳滤膜之间,截留分子质量为500~2 000 Da,但经此膜处理后的浓缩液污染物浓度上升到一个新的水平,通过常规的深度处理很难达标排放。
芬顿氧化法具有处理效率高、操作简单、运行便捷等优点,在处理印染废水时,能够降解污水中存在的持久性有机污染物,具有十分广阔的应用前景[22-27]。本研究采用芬顿法、物化法及类芬顿法对印染废水小孔径超滤膜浓缩液进行深度处理研究,寻求最佳处理方案及其最优条件,保障产水水质达到《纺织染整工业水污染物排放标准》(GB 4287-2012)排放要求,为印染废水近零排放提供工程实践依据。
芬顿法处理印染废水小孔径超滤膜浓缩液
Fenton process treating small pore-sized ultrafiltration membrane concentrate of printing and dyeing wastewater
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摘要: 印染废水属于难处理工业废水,具有排放量大、污染物含量高等特性。在可持续发展的背景下,印染废水实现零(近零)排放成为必然趋势。目前采用催化氧化法处理膜浓缩液是实现零(近零)排放的常规方法,但该方法存在催化药剂投加量大、处理效果差及二次污染等问题。采用芬顿法,以印染废水小孔径超滤膜浓缩液为实验用水,考察了H2O2和FeSO4·7H2O投加量、pH及加药时间间隔等因素对处理效果的影响。结果表明,在COD∶H2O2质量比为1∶1.3、H2O2∶Fe2+ 摩尔比为1∶1,反应初始pH=4.0,反应回调pH=6.5,加药时间间隔60 min的条件下,处理效果最优,出水COD、色度、氨氮和总氮等主要水质指标均达到《纺织染整工业水污染物排放标准》(GB 4287-2012)排放要求,出水水质稳定,较其他条件能够获得较高的经济效益。与此同时,将芬顿法与物化和类芬顿法进行了对比分析,结果表明,芬顿法处理印染废水膜浓缩液具有较高的经济性,为进一步工程实践提供依据。Abstract: Printing and dyeing wastewater is a kind of refractory industrial wastewater, which has the characteristics of large discharge and high pollutant content. In the context of sustainable development, zero (nearly zero) discharge of printing and dyeing wastewater has become an inevitable trend. At present, the treatment of membrane concentrate by catalytic oxidation is a conventional method to achieve zero ( nearly zero) emission, while it has the problems of large dosage of catalytic agent, poor treatment effect and secondary pollution. In this study, Fenton method was used to treat the small pore-sized ultrafiltration membrane concentrate of printing and dyeing wastewater. The effects of H2O2 and FeSO4·7H2O dosage, pH and dosing time interval on the treatment effect were investigated. The results showed that the best treatment effect occurred at mass ratio COD : H2O2 of 1:1.3, molar ratio H2O2 : Fe2+ of 1:1, initial pH 4.0, callback pH 6.5 and dosing time interval of 60 min. All the main water quality indexes such as COD, color, ammonia nitrogen and total nitrogen in the effluent could meet the emission requirements of ‘Discharge Standard of Water Pollutants for Textile Dyeing and Finishing Industry’ (GB 4287-2012). The effluent quality was stable, this method could obtain higher economic benefits than other conditions. At the same time, this study compared the Fenton method with the physicochemical and Fenton-like methods. The results showed that the Fenton method had higher economy in treating membrane concentrate of printing and dyeing wastewater, which provides a basis for further engineering practice.
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表 1 实验用水水质
Table 1. Quality of experimental water
水样 pH 色度/倍 浊度/NTU 电导率/(mS·cm−1) COD/(mg·L−1) 总碱度(以CaCO3计)/
(mg·L−1)S1 8.5 1 800 0.73 21.10 1 443 2 752 S2 8.6 1 900 0.83 19.50 1 414 2 638 S3 8.6 3 500 2.25 19.24 2 300 2 552 S4 8.6 5 500 1.19 18.80 2 694 2 430 表 2 正交实验因素水平表
Table 2. Factor level table for orthogonal experiments
水平 反应初始
pH(A)FeSO4·7H2O
投加量(B)/
(g·L−1)H2O2
投加量(C)/
(mg·L−1)投药间隔
时间(D)/
min反应回调
pH(E)1 2.5 4.09 500 30 6.5 2 3.0 8.18 1 000 40 7.0 3 3.5 12.27 1 500 50 7.5 4 4.0 16.36 2 000 60 8.0 表 3 影响因素正交实验结果
Table 3. Orthogonal experimental results of influencing factors
序号 A B C D E 色度去除率/% COD去除率/% 1 1 1 1 1 1 3.81 62.50 2 1 2 2 2 2 89.32 83.29 3 1 3 3 3 3 94.15 87.50 4 1 4 4 4 4 95.48 83.56 5 2 1 2 3 4 62.54 72.77 6 2 2 1 4 3 69.58 73.55 7 2 3 4 1 2 97.73 90.92 8 2 4 3 2 1 96.60 89.87 9 3 1 3 4 2 77.48 83.16 10 3 2 4 3 1 96.03 88.29 11 3 3 1 2 4 84.67 72.37 12 3 4 2 1 3 93.75 85.00 13 4 1 4 2 3 90.40 81.18 14 4 2 3 1 4 92.53 83.68 15 4 3 2 4 1 92.15 84.61 16 4 4 1 3 2 77.65 65.13 表 4 正交实验色度结果极差分析
Table 4. Range analysis of orthogonal experiment color result
序号 A/% B/% C/% D/% E/% 均值11 70.69 35.96 58.93 71.95 72.15 均值12 81.61 86.86 84.44 90.25 85.55 均值13 87.98 92.18 90.19 82.59 86.97 均值14 88.18 90.87 94.91 83.67 83.81 极差R1 17.49 33.62 35.98 18.29 14.82 表 5 正交实验COD结果极差分析
Table 5. Range analysis of orthogonal experiment COD result
序号 A/% B/% C/% D/% E/% 均值21 79.21 74.90 68.39 80.53 81.32 均值22 81.78 82.20 81.41 81.68 80.63 均值23 82.21 83.85 86.05 78.42 81.81 均值24 78.65 80.89 85.99 81.22 78.09 极差R2 3.56 8.95 17.66 3.25 3.71 表 6 确定影响因素条件表
Table 6. Determined condition table of influencing factors
条件 反应
初始pHFeSO4·7H2O
投加量/
(g·L−1)H2O2投加量/
(mg·L−1)投药间隔
时间/min反应
回调pH1 3.8 25.12 3 000 60 6.5 2 4.0 25.12 3 000 40 6.5 3 4.2 25.12 3 000 60 6.5 4 4.0 25.12 3 000 60 6.5 5 4.0 25.12 3 400 60 6.5 6 4.0 25.12 3 800 60 6.5 表 7 检测水质表
Table 7. Detection of water quality table
序号 pH 浊度/
NTU色度/
倍电导率/
(μS·cm−1)COD/
(mg·L−1)氨氮/
(mg·L−1)总氮/
(mg·L−1)总磷/
(mg·L−1)六价铬/
(mg·L−1)SS/
(mg·L−1)二氧化氯/
(mg·L−1)苯胺/
(mg·L−1)限值 6~9 — 80 — 200 20 30 1.5 不得检出 177 0.5 不得检出 浓缩液 8.6 12.2 3 500 1 924 2 300 5.59 76.90 2.58 未检出 26 未检出 1.4 1 7.0 0.4 65 2 920 144 10.05 28.67 0.05 未检出 未检出 未检出 未检出 2 7.0 0.4 70 2 940 144 9.92 27.94 0.07 未检出 未检出 未检出 未检出 3 7.0 2.0 75 2 950 150 11.54 29.23 0.05 未检出 未检出 未检出 未检出 4 6.5 0.8 60 2 940 138 9.73 26.84 0.06 未检出 未检出 未检出 未检出 5 6.7 1.3 70 2 970 135 10.05 28.76 0.06 未检出 未检出 未检出 未检出 6 6.5 0.6 55 3 020 143 9.78 28.15 0.06 未检出 未检出 未检出 未检出 表 8 物化实验、类芬顿实验、芬顿实验处理水质效果对比
Table 8. Comparison of the treatment effects on the water quality by physicochemical experiment, Fenton-like experiment and Fenton experiment
水样 COD/
(mg·L−1)COD去除率/% 色度/
倍色度去除率/% 原水 2 694 — 5 500 — PFS处理水 1 366 49.29 2 500 54.55 PAC处理水 1 964 27.10 4 800 12.73 类芬顿处理水 68 97.48 10 99.82 芬顿处理水 172 93.62 80 98.55 表 9 不同实验方法吨处理废水所需药剂
Table 9. The reagent dosage for treating wastewater by different experimental methods kg·t−1
水处理法 H2SO4 H2O2(30%) FeSO4·7H2O NaOH PAM AC FeCl3·6H2O PFS PAC PFS法 4 — — 2.0 0.001 — — 1 — PAC法 4 — — 2.0 0.001 — — — 0.6 类芬顿法 4 11 — 1.5 0.001 35 13.3 — — 芬顿法 4 11 26.98 2.0 0.001 — — — — -
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