Treatment of tannery wastewater by electrocoagulation

Treatment of tannery wastewater by electrocoagulation with low cell current （≤ 1A） and soluble electrodes （mild steel electrodes and aluminum electrodes） was studied. Compared with aluminum electrodes, mild steel electrodes were more effective for the removal of sulfide, with a removal efficiency of over 90%. But during the treatment process, black color precipitate typical to iron（Ⅱ） sulfides was produced. While aluminum electrodes were effective to eliminate the colority of the effluent, the removal efficiency of sulfide was lower than 12%. The mechanisms of the removal of chemical oxygen demand, ammonia, total organic carbon, sulfide and colority with the two soluble electrodes （mild steel and aluminum electrodes） were discussed in detail. In order to exert the predominance of diffenent types of electrodes, the tannery wastewater was treated using mild steel electrodes first followed by the filter and finally by the aluminum electrodes, the elimination rates of chemical oxygen demand, ammonia, total organic carbon, sulfide and colority were 68.0%, 43.1%, 55.1%, 96.7% and 84.3%, respectively, with the initial concentrations 2413.1 mg/L, 223.4 mg/L, 1000.4 mg/L, 112.3 mg/L and 256 dilution times, respectively. The absorbance spectra and energy consumption during electrocoagulation process were also discussed.

Removing contaminants from tannery wastewater by chemical precipitation using CaO and Ca(OH)2

The removal of Cr,sulfates and Chemical Oxygen Demand(COD)from industrial tannery wastewater by chemical precipitation was carried out using Calcium oxide(CaO)and Calcium hydroxide(Ca(OH)2).Different doses of alkalis,ranging from deficiency to excess hydroxyl species over the stoichiometric necessary,were used to remove theoretically the 100%of Cr[0.3-3.2 g alkali·(g Cr^3+)^-1].The precipitation was carried out at room temperature,10 min of vigorous stirring,200 r·min^-1 and a settling time of 24 h,followed by separation and characterization of liquid product.As result of addition of alkalis,pH underwent increase as did the alkali concentration.The removal of Cr,and sulfates also increased as alkali concentration did,although for first species the changes at higher alkali contents were less evident.COD removal on the other hand,did not follow a unique trend,instead exhibited a maximum.Based on our results,selection of a specific dose of alkali was carried out taking as reference the efficiency on total chromium removal,keeping the pH in the range 7 to 9 to ensure Cr precipitation as chromium hydroxide.With those conditions,jar test was used to produce enough liquid product in order to determine the removal percent of several other species.The removal percent of the species was as follows:Cr,SO4^2-,ZnSO4,FeSO4,CN^-1,NiSO4,Fe2[Fe(CN)6]at 99.8%,66.9%,99.6%,21.4%,70.9%,52.8%and 76.4%with CaO,and 99.8%,61.6%,99.9%,7.1%,84.0%,54.4%and 90.5%with Ca(OH)2,respectively.

Treatment of Tannery Wastewater by the Application of Electrocoagulation Process Using Iron and Aluminum Electrodes

Until relatively recently, little has been done of effective technique “zero effluent” to conserve energy and water. Tannery wastewater is known as complex characteristics. In this study batch electrocoagulation experiments were carried out to assess the removal of color and chemical oxygen demand (COD) from tannery wastewater using two types of electrode materials: aluminum and iron. The effects of current density, electrolysis time and initial pH were investigated for tannery wastewater. Therefore, the operating costs for each electrode have been calculated. Based on results, it can be concluded that iron is tremendous to aluminum as electrode material, from COD removal and energy consumption views. All the conclusions of the study revealed that treatment of tannery by EC can be applied as a step of a hybrid treatment.

华北平原制革废水Cr(Ⅲ)和氨氮在典型包气带中迁移模拟与污染评价

【研究目的】为探明制革废水中的特征污染物铬(Cr(Ⅲ))和氨氮(NH_(4)^(+)–N)在华北平原典型包气带中的迁移规律,评价其可能产生的土壤与地下水污染风险。【研究方法】采用土柱淋滤实验研究Cr(Ⅲ)和NH_(4)^(+)–N在典型粉土中的吸附和迁移转化特征,结合Hydrus–1D建立的包气带水流和溶质运移模型,模拟预测深0.5 m渗坑中NH_(4)^(+)–N连续入渗状态下通过包气带到达地下水面所需时间及不同深度浓度值的变化规律。【研究结果】在3 cm定水头,污染液(Cr(Ⅲ)20 mg/L,NH_(4)^(+)–N 250 mg/L)定浓度持续淋滤120 d的情况下,Cr(Ⅲ)在土柱中垂向迁移距离小于10 cm,且以残渣态(73%)为主,未检出Cr(VI)。NH_(4)^(+)–N则迁移能力较强,淋滤40 d后即穿透50 cm厚粉土柱。在高含盐量(电导率为10.08 ms/cm)条件下,NH_(4)^(+)–N在粉土中的迁移主要受吸附作用控制,土-水分配系数为25.87 L/kg,未发生硝化作用。持续淋滤150 d时NH_(4)^(+)–N迁移至地下水面(18 m埋深)且浓度超过Ⅲ类地下水质量标准(0.5 mg/L,GB/T 14848–2017),在223 d完全穿透包气带,严重污染地下水。【结论】高含盐量制革废水中Cr(Ⅲ)在粉土中迁移能力较弱,且难以被氧化为Cr(Ⅵ),对地下水威胁较小。NH_(4)^(+)–N则随水流快速迁移至地下水面,严重威胁地下水安全。

TiO_(2)/ZnO/SnO_(2)的制备及光臭氧协同催化深度处理制革废水

采用溶剂热法制备了复合金属氧化物催化剂(TiO_(2)/ZnO/SnO_(2)),以生化制革废水为处理对象,废水COD为110~140 mg/L,对催化剂光催化臭氧氧化性能进行了探。考察了催化剂种类、反应时间、催化剂用量、臭氧浓度等因素对生化制革废水COD去除率的影响。XPS、XRD、UV-Vis DRS、SEM、TEM及FT-IR等结果证明,实现了复合金属氧化物催化剂的制备。光催化臭氧氧化实验结果表明,与单独光催化和臭氧催化氧化相比,光催化臭氧氧化能明显提高生化制革废水的COD去除率。当催化剂用量为0.8 g/L,臭氧浓度20 mg/L,复合催化剂光催化臭氧氧化效果最佳,反应150 min后,COD去除率达到83.7%。重复实验结果表明TiO_(2)/ZnO/SnO_(2)稳定性较好。本研究利用光催化和臭氧催化氧化协同作用深度处理制革废水,效率较高、无二次污染,可为工业污水深度处理提供参考。

基于绿色发展的制革污水处理技术研究

为了应对制革业的环境问题,本文基于绿色发展理念,对制革污水处理方法进行了深入分析。概述了制革污水的主要污染物及其对环境和人类健康的危害,指出了传统污水处理方法在去除有机物、重金属等方面的不足,以及其造成的高能耗、高成本等问题。介绍了基于绿色发展的污水处理技术中的清洁化生产原则及具体技术(如先进氧化工艺、膜分离技术和生物吸附技术等)。这些技术能够有效地降低制革污水的污染负荷,提高资源利用率,实现制革业的可持续发展。

生物增效技术处理制革废水的试验研究

生物增效技术可以显著提高废水处理效果。在处理前,废水中的有机物质和重金属离子含量较高,COD和BOD_(5)浓度都超过了国家排放标准。经过生物增效技术处理后,废水中的COD和BOD_(5)浓度明显降低,并符合国家排放标准要求。本试验结果表明,生物增效技术是一种高效、经济、环保的制革废水处理方法,可以降低废水中有机物质的含量,并达到国家排放标准要求。同时,生物增效技术还能促进废水中有益菌群的生长,改善废水的微生物环境。因此,生物增效技术在制革废水处理中具有广阔的应用前景。

Tannery wastewater treatment:conventional and promising processes,an updated 20-year review

Mismanagement of various wastes especially waste water produced by tanning processes has caused serious environmental problems and ultimately impaired human health.Constant efforts have been making to alleviate the pollution of tannery wastewater(TWW),yet terminal treatment still takes dominance.In this review,research onTWW treatment from 2000 to 2021 was summarized,and main methods such as coagulation and flocculation,adsorption,biological treatment,membrane filtration,advanced oxidation process were briefly discussed.More detailed introduction was given to the method of electrochemical treatment since it has excellent performance such as environmental friendliness and high efficiency,hence attracting more and more research attention in recent years.In view of the harsh physi-chemical conditions of TWW,integrated or combined treatment methods are accordingly recommended with better performance and multi-function,however comprehensive studies on optimization of methods combination and cost-effectiveness are needed.The certain issues that the residue Cr in treatment sludge and high salinity in effluent still remain were put forward in this work and potential solutions were provided.Moreover,this review proposed the perspective that realizing multi-function,recycling,and intensification should be the developing direction for future TWW treatment.This review is expected to provide a general guide for researchers who aspire to ameliorate TWW pollution problems and understand various methods utilized in this field.

制革行业物化污泥制备再生水处理剂研究

为实现制革行业污泥减量化、无害化、资源化的目标,以水洗-酸溶解为核心工艺,对制革物化污泥制备水处理剂的可行性进行了研究。研究表明,物化污泥的最佳煅烧温度为1000℃;最佳水洗条件为固液比1∶10,水洗时间1 h,水洗次数2次;最佳酸溶解条件为固液比5 g/L,酸浓度0.5 mol/L,酸溶解温度20℃,酸溶解时间0.5 h;溶液中Cr^(6+)最佳还原条件为摩尔比(还原剂∶Cr^(6+))16∶1,还原温度40℃。在本文的工艺条件下,制革行业的物化污泥可实现最佳的减量化和资源化利用目标。

电位滴定法测定制革废水化学需氧量的实验设计

建立了密闭氧化消解-自动电位滴定测定化学需氧量COD的方法,并对所建立方法的准确度、精密度进行了评估。将此方法应用于制革废水COD的测定,在加标回收实验中,加标30 mg/L的试样,回收率为94.453%,加标60 mg/L的试样,回收率为105.132%。将建立的新方法与国标法进行了对比,实验发现,两种方法的相对标准偏差都在3%以内。因此所建立的方法是可行的,该方法能够应用于实践研究,且操作方便,节约试剂,效率高,避免肉眼目测对测定结果带来的主观误差,使测定结果更加客观准确。在此实验过程中,提高了学生的动手实践能力,培养了学生的主观能动性,激发了学生对科研的兴趣。

乡村治理背景下皮革行业废水处理策略研究

乡村治理是完成我国乡村振兴的重要一步,皮革行业由于自身产污问题,给乡村治理带来环境问题,如何解决皮革行业废水处理难题,关系着乡村治理的成败。本文梳理了皮革行业的基本情况,总结了制革废水危害及处理方式,并提出若干治理策略,为推进乡村治理现代化提供参考。

高铁酸钾-Fenton联合氧化处理制革综合废水

针对制革综合废水中COD和Cl^(-)偏高的问题,采用单因素和正交实验方法,研究了高铁酸钾和Fenton单独及联合氧化处理制革综合废水。结果表明:与单独使用高铁酸钾或Fenton氧化相比,高铁酸钾-Fenton联合氧化具有相互促进作用,能显著提高制革废水中COD和Cl^(-)的去除效果,有利于后续的生物处理与废水回用。综合考虑处理效率和经济成本,得到联合氧化的最佳工艺条件:高铁酸钾氧化废水初始pH=9,K2 FeO4投加量为5 g·L^(-1),反应时间30 min;Fenton氧化pH=3,H2 O2投加量为12.5 mL·L^(-1),反应时间60 min;此条件下,制革综合废水的COD和Cl^(-)去除率分别为88.36%和86.96%。

氧化石墨烯/多孔SiO_(2)微球复合材料的吸附性能研究

制革原料皮在加工过程中会产生大量的蛋白质残留物,利用吸附剂从制革废水中分离回收蛋白质可以实现制革废水污染物的循环使用。以鱼皮胶原蛋白为生物质模板,加入氧化石墨烯(GO)粉末,合成了氧化石墨烯/多孔SiO_(2)微球复合材料(GO/C-PSM)。以蛋白水解酶溶菌酶(LZ)为理论研究对象,结果表明GO/C-PSM对LZ的最大吸附量为45.4 mg/g,吸附过程与拟二级吸附动力学模型相符,同时GO/C-PSM对LZ的吸附等温线模型与Langmuir等温线模型相契合。GO/C-PSM在经过5次循环后,吸附率仍达到80%以上。此外,GO/C-PSM对实际制革工业废水中的蛋白质也有一定的吸附分离效果。

“双碳”视角下制革工业重金属废水处理工艺与效果研究

从“双碳”视角出发,简述了制革废水中重金属元素的来源及其对人体与环境的危害,分析了制革工业水污染防治发展趋势。介绍了几种制革废水处理新工艺及其应用情况,包括吸附法、膜分离法、新型电絮凝法和生物絮凝法。并基于磁强化电絮凝工艺进行制革废水处理效果的试验分析。结果表明,该工艺对总镍、总铬、总铅、总铜4种重金属的去除率均大于99%,满足污染物排放标准要求;相比于普通电絮凝工艺,该工艺对重金属去除率更高,且能耗更低,有助于制革工业践行“双碳”战略,推进“双碳”战略目标落地。

环境规制下制革工业含铬废水脱铬处理与回收利用研究

环境规制直接或间接地影响制革工业的生产经营和防污治理,从金融、政策和技术方面引导着制革工业的绿色可持续发展。对此,本文简述了环境规制下制革工业今后的发展趋势,分析了含铬废水脱铬处理工艺研究现状与含铬废水回收利用价值。采用重金属捕集剂联合絮凝剂对某皮革厂含铬废水进行脱铬处理试验,确定试验过程与方案,并研究了不同试验条件对含铬废水脱铬效果和铬回收率的影响。结果表明:随着絮凝剂和助凝剂含量的增加,含铬废水的脱铬率呈上升趋势,在二者添加量分别为2.5 mg/L和0.2 mg/L时,脱铬处理效率最佳;在酸浸法回收铬的过程中所用硫酸浓度取6 mol/L较为适宜。

Tannery wastewater treatment:conventional and promising processes,an updated 20-year review

Mismanagement of various wastes especially waste water produced by tanning processes has caused serious environmental problems and ultimately impaired human health.Constant efforts have been making to alleviate the pollution of tannery wastewater(TWW),yet terminal treatment still takes dominance.In this review,research on TWW treatment from 2000 to 2021 was summarized,and main methods such as coagulation and flocculation,adsorption,biological treatment,membrane filtration,advanced oxidation process were briefly discussed.More detailed introduc-tion was given to the method of electrochemical treatment since it has excellent performance such as environmental friendliness and high efficiency,hence attracting more and more research attention in recent years.In view of the harsh physi-chemical conditions of TWW,integrated or combined treatment methods are accordingly recommended with better performance and multi-function,however comprehensive studies on optimization of methods combina-tion and cost-effectiveness are needed.The certain issues that the residue Cr in treatment sludge and high salinity in effluent still remain were put forward in this work and potential solutions were provided.Moreover,this review pro-posed the perspective that realizing multi-function,recycling,and intensification should be the developing direction for future TWW treatment.This review is expected to provide a general guide for researchers who aspire to ameliorate TWW pollution problems and understand various methods utilized in this field.

预处理-AO-芬顿氧化-人工湿地组合工艺处理制革废水

为了解决某制革企业生产废水处理工艺出水化学需氧量、氨氮难达标的问题,采用“预处理-AO-芬顿氧化-人工湿地”组合工艺对制革废水进行处理。深度处理采用芬顿氧化工艺,能降解废水中的难降解有机物,并通过人工湿地生态系统进一步实现污水的高效净化。处理后出水化学需氧量≤100 mg/L,五日生化需氧量≤20 mg/L,氨氮≤10 mg/L,硫化物≤0.5 mg/L,总铬≤1.5 mg/L,出水水质满足广东省地方标准《水污染物排放限值》(DB44/26—2001)第二时段一级标准和《制革及皮毛加工工业水污染物排放标准》(GB 30486—2013)中表2制革企业直接排放限值。该工艺能有效去除制革废水中的污染物,具有较好的经济效益和环境效益。

Facile fabrication of functional cellulose paper with high-capacity immobilization of Ag nanoparticles for catalytic applications for tannery wastewater

It has been a research goal to develop macroscopic materials with an optimized surface structure to affix silver nanoparticles which could contaminate water and maximize their practical functions.Cellulose paper is a versatile biomass material valued for its abundance,low cost,biocompatibility,and natural composition.Until now,its potential application in water purification has not been adequately explored.In this study,gallic acid-modified silver nanoparticles(GA@AgNPs)were loaded onto commercial cellulose filter paper using a simple lipoic acid modification process(GA@AgNPs-LA-CP).Scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),and X-ray diffraction(XRD)were used to characterize the GA@AgNPs-LA-CP.The catalytic activity of the GA@AgNPs-LA-CP was evaluated by the reduction reaction of methylene blue(MB),Rhodamine B(RhB),and 4-nitrophenol(4-NP)with sodium borohydride(NaBH4).The GA@AgNPs-LA-CP exhibited excellent catalytic activity toward MB,RhB,and 4-NP,taking advantage of its high specific surface area generated by the cellulose fiber network structure.Interestingly,due to the electrostatic interactions between the cationic dyes and the GA@AgNPs,the as-prepared catalytic composite material serves as a better catalyst for MB and RhB,suggesting dual applications of the composite materials for organic wastewater treatment and the removal of harmful dyes.This implies that the immobilization of AgNPs on cellulose papers is an effective method and can be applied to efficient wastewater treatment applications.

制革废水处理技术研究进展

近年来随着制革工业的发展,制革废水的排放造成了严重的水体污染,同时废水中含有的有毒有害物质对人体健康也产生了极大的威胁,因此,寻求一种高效、经济可行的制革废水处理技术有着重要的意义。由于制革废水成分非常复杂且含有许多有毒物质及高浓度的盐类,使得制革废水的治理异常困难。目前在制革废水治理的研究中取得了许多新的重要进展,通过对各种治理方法的分析提出了制革废水处理的发展方向。

国内制革废水处理工艺研究现状

针对国内制革综合废水的处理研究,从一级物化处理和二级生化处理两个方面做了概括。就一级物化处理而言,介绍了国内制革废水处理的发展过程,并指出了制革废水处理的发展方向———绿色化学技术;在制革废水的二级处理工艺研究上,介绍了制革废水处理中的曝气工艺、氧化沟工艺、SBR工艺、生物膜等在国内制革废水处理上的理论及应用研究情况,针对国内制革企业普遍规模较小的特点,认为SBR工艺是较适于国内制革废水特点的处理工艺。