Pilot study on microbial treatment of high concentration chromium wastewater from cold rolling mills

The microbial treatment of wastewater containing a high concentration of chromium from cold rolling mills was carried out as a pilot study. The pilot-scale equipment, technological process and results are described in this paper. Two kinds of wastewater with a high concentration of chromium were tested ： one from a color coating line ; the other from a silicon steel line. The removal effect of Cr^6＋ , T-Cr and chemical oxygen demand （COD） in wastewater was studied. The results showed that this microbial treatment technology could be used to treat the above two kinds of chromium-containing wastewater. The average concentrations of Cr^6＋ in the color coating line effluent and the silicon steel line effluent were 0.02 mg/L and 0.04 mg/L respectively, and the average concentrations of T-Cr in the effluents were 0.71 mg/L and 0.74 mg/L respectively. Both were lower than the Sewage Discharge Standard （Cr^6＋ 〈 0.5 mg/L,T-Cr 〈 1.5 mg/L）. Furthermore, up to 60% of the COD was removed from chromate wastewater containing a high concentration COD （ 〉 3 g/L）. The removal rate of COD was lower than 25% for chromate wastewater containing a low concentration COD （ 〈 3 g/L）. Adding a flocculating agent was one of the effective ways of improving the COD removal rate from chromium-containing wastewater.

A Study on Zeolite Performance in Waste Treating Ponds for Treatment of Palm Oil Mill Effluent

Oil palm currently occupies the largest acreage of farm land in Malaysia. In 2011, the production of palm oil in Malaysia was recorded as 19.8 million tons which has led to a huge amount of wastewater known as palm oil mill effluent (POME). This work focuses on the ponding system which acts as wastewater treatment plant in order to treat POME. The conventional ponding system applied in mills consists of a series of seven ponds. The maintenance costs of the pond are expensive thus study of alternative methods is needed. POME treatment using zeolite shows a potential to overcome the problem. Samples collected from selected ponds are tested and analyzed using water analyzer method. Result from adsorption by zeolite shows a significant reduction of COD, BOD, Fe, Zn, Mn and turbidity. This shows that zeolite is highly potential to be applied as adsorbent in the POME treatment plants. The results here may lead to lower maintenance cost, lower quantity of treatment ponds and lesser land occupied for the treatment of POME in Malaysia.

An improved implementable process for the synthesis of zeolite 4A from bauxite tailings and its Cr^(3+) removal capacity

A simple and practical method for the synthesis of zeolite 4A from bauxite tailings is presented in this paper. Systematic investigations were carried out regarding the capacity of zeolite 4A to remove Cr（III） from aqueous solutions with relatively low initial concentrations of Cr（III）（5–100 mg·L^（-1））. It is found that the new method is extremely cost-effective and can significantly contribute in decreasing environmental pollution caused by the dumping of bauxite tailings. The Cr（III） removal capacity highly depends on the initial p H value and concentration of Cr（III） in the solution. The maximum removal capacity of Cr（III） was evaluated to be 85.1 mg×g^（-1） for zeolite 4A, measured at an initial p H value of 4 and an initial Cr（III） concentration of 5 mg·L^（-1）. This approach enables a higher removal capacity at lower concentrations of Cr（III）, which is a clear advantage over the chemical precipitation method. The removal mechanism of Cr（III） by zeolite 4A was examined. The results suggest that both ion exchange and the surface adsorption-crystallization reaction are critical steps. These two steps collectively resulted in the high removal capacity of zeolite 4A to remove Cr（III）.

Ability of Bacillus mucilaginosus GY03 Strain to Adsorb Chromium Ions

A research with Bacillus mucilaginosus cultured in nitrogen-free medium for forming a flocculant material to adsorb Cr+6 was conducted to determine the effects of different pH, volume, treatment time, and chromium (Ⅵ) concentrations on chromium (Ⅵ) adsorption by microbial flocculant (MBF), which was produced from the B. mucilaginosus GY03 strain. The results showed that MBF had outstanding flocculation on chromium (Ⅵ). Based on the results of a oneway experiment and actual wastewater treatment conditions, the optimum conditions, obtained by using orthogonal experiments, for chromium (Ⅵ) adsorption by MBF were: Cr6+ solution pH of 9, flocculant material volume of 15 mL,treatment time of 12 h and chromium ion concentration of 30 mg L-1. The results demonstrated that the MBF produced from GY03 could be used in the chromium-containing wastewater treatment. Meanwhile, after extraction and analysis of the MBF polysaccharides, it was found that MBF was mainly composed of glycoprotein. Analysis on constituents of monosaccharide showed that polysaccharides of B. mucilaginosus were composed of rhamnose, glucose etc. Thus, because it was applied over a wide range of pH, in small amounts and had a rapid flocculation speed the flocculant used in this experiment had a vast field of application potential.

Microwave-assisted Fenton-like decolorization of methyl orange solution using chromium compounds

Azo dyes discharged in the environment are persistent organic pollutants (POPs),which are very difficult to remove. We developed a microwave-assisted Fenton-like process to degrade methyl orange (MO),an azo dye,with hydrogen peroxide (H2O2) catalyzed by chromium compounds coexisting with MO in the solution. Comparison between the Cr(Ⅲ)-H2O2 and Cr(VI)-H2O2 systems shows that Cr(VI) has a stronger and more stable catalytical activity than Cr(Ⅲ),and Cr(Ⅲ) is more susceptible to a change in the acidity or alkalinity of the reaction system. With a Cr(VI) concentration of 10 mmol L-1 or a Cr(Ⅲ) concentration of 12 mmol L?1 in the solution under the microwave irradiation of a power larger than 300 W for 3 min,10 mmol L-1 H2O2 can degrade more than 95% of 1 000 mg L-1 methyl orange; when the microwave power is increased to 700 W,the same amount of H2O2 can degrade all methyl orange in the solution with the same amount of Cr(VI) catalyst. Ultraviolet-visible spectrography indicates the cleavage of the azo bond in methyl orange after treatment,suggesting the potential of this Fenton-like process to degrade azo dye POPs. Reusing waste chromium compounds coexisting with dyestuff in wastewater to catalyze the degradation of azo dyes could be a cost-effective technique for azo dyes and chromate manufacturers and/or users to treat their wastewater and prevent POPs from endangering the environment. This is of particular importance to controlling the water quality of the Three Gorges Reservoir.

Influence of Temperature on Equilibrium, Kinetic and Thermodynamic Parameters of Biosorption of Cr(VI) onto Fish Scales as Suitable Biosorbent

In this work the potential of fish scales as a suitable biosorbent for removal of Cr(VI) ions from aqueous solutions was investigated at various temperatures. The influence of temperature on equilibrium, kinetics as well as thermodynamic parameters was investigated. Various isotherm models such as Langmuir, Freundlich, R - P, D - R, Temkin and Halsey were used for the mathematical description of the biosorption of Cr(VI) ions onto fish scales. It was observed that Freundlich model exhibited the best fit to experimental data. Amongst the various kinetic models tested, the pseudo-first-order kinetic model represented the best correlation for the biosorption of Cr(VI) onto fish scales at various temperatures. In addition, various thermodynamic parameters such as ?Go, ?Ho and ?So were also determined. The biosorption of Cr(VI) was found to be a spontaneous and endothermic process.

沸石的改性及其处理养殖尾水中抗生素的性能研究

沸石是一种产量丰富的无机非金属矿石,其作为环境友好材料在水污染治理方面发挥巨大作用。综述了沸石的改性及其处理养殖尾水中不同类型抗生素等两个方面,并提出研究展望。

Heterogeneous Fenton Catalyst for the Efficient Removal of Azo Dyes in Water

Heterogeneous Fenton/photo Fenton type processes using a Fe-exchanged zeolite of Y-type have been applied for the degradation of a model textile synthetic water based on Black B azodye. Research work has been directed to compare process efficiency and to establish their advantages over corresponding homogenous Fenton type processes. By optimizing the amount of reactants and process conditions, a complete decolorization of the effluent and a reduction greater than 80 per cent in the total organic carbon content is achieved. The influence of solar radiation on the heterogeneous process has been also studied. Homogeneous and heterogeneous Fenton processes yielded similar decolorization and mineralization, but the concentration of Fe ions in the bulk after the treatment was not significant in the latter case. Moreover, the catalyst support can be reused in successive cycles without significant loss of effectiveness. The use of solar radiation as a source of energy for operating the process accelerates the decomposition of azodye, making the process economical and environmentally sustainable.

活性铁的制备及其处理废水的特性研究

本文优化了活性铁的制备方法,研究了利用活性铁体系各组分处理含腐植酸、铬或镍废水的特性及作用机理,并对活性铁及其反应产物进行了XRD、FTIR和SEM表征。结果表明:(1)先通氮气5 min,再摇床反应7 h所得活性铁性能最佳,零价铁表面基本被粒径为50~100 nm蓬松Fe_(3)O_(4)颗粒覆盖;(2)活性铁体系中混杂存在的Fe 0、Fe^(2+)、Fe_(3)O_(4)及其他铁(氢)氧化物对腐植酸的去除具有协同效应,原液中强化Fe^(2+),可将腐植酸的去除率从70.1%提高到99.3%;(3)活性铁体系原液对重金属铬和镍的去除效率均接近100%。六价铬的去除主要依靠零价铁与六价铬之间的氧化还原反应完成,而二价镍主要是通过活性铁中四氧化三铁的吸附及与二价铁反应形成稳定的镍氢氧化物沉淀的方式去除。

MOFs功能材料在重金属废水处理中的应用研究

随着经济的快速发展,工业废水、生活废水、污水灌溉、农药喷洒和化肥使用等,对农产品或土壤造成严重的重金属污染,对人类的身体健康造成严重威胁,因此高效、快速地解决重金属污染问题,成为当今社会亟待解决的问题。金属有机框架材料(MOFs)是一类新型功能材料,具有结构可调、比表面积大和孔隙率高等优点,在重金属废水处理方面具有良好的应用前景。本文详细地综述了近年来MOFs功能材料在重金属铬、汞和铀废水处理中的应用研究进展,并对MOFs功能材料在重金属废水处理中的应用前景进行了总结和展望。

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。

氨氮废水处理用新型沸石化陶粒的制备

以粉煤灰、铁尾矿为主要原料,采用高温烧结活化-水热合成工艺制备了新型沸石化陶粒。利用高温烧结得到烧结陶粒的同时对原料中的莫来石等惰性相产生活化作用,后续采用水热反应对基础陶粒进行沸石化改性,增加其比表面积及吸附能力。研究表明最佳的制备工艺条件为:m(粉煤灰)∶m(铁尾矿)∶m(石英砂)=7∶1∶2,烧结温度1040℃,烧结时间30 min,NaOH溶液浓度1.5 mol/L,水热温度160℃,水热时间12 h。XRD、SEM、FT-IR和Raman结果表明,制备的沸石化陶粒的主晶相为P型沸石和方沸石,其比表面积从基础陶粒的1.068 m^(2)/g增加至35.770 m^(2)/g,同时,对NH_(4)^(+)-N离子的最大吸附容量由基础陶粒的1.82 mg/g增加至13.34 mg/g,分别增加至基础陶粒的33.49倍和7.33倍,结果表明沸石化陶粒在废水处理中具有潜在的应用前景。

含铬(VI)废水处理技术研究进展

铬是工业中广泛使用的一种过渡金属,其铬(VI)具有极强的毒性和致畸、致癌作用,严重威胁人体健康及生态环境安全。因此,探索价廉、高效、绿色的含铬废水处理技术具有重要现实意义。本文通过综述不同处理技术在含铬废水处理中的应用,对比分析各处理方法的优缺点,并对含铬废水处理技术的发展方向进行展望,从而为含铬废水的处理研究及实际工程应用提供理论支撑。

免曝气混合填料反应器处理生活污水的性能

采用沸石-塑料混合填料为载体构建固定床生物膜反应器,周期性进水(厌氧)-排水(好氧)富集培养聚糖菌(GAOs),结合沸石颗粒吸附作用实现厌氧条件下COD和氨氮的去除。在进水COD和氨氮浓度分别为(508±19)mg/L和(40±3)mg/L、HRT为12 h(厌氧6 h、好氧6 h)的运行条件下,单级反应器COD、氨氮和总氮去除率分别为89.2%、57.5%、57.5%。双级反应器条件下,COD、氨氮和总氮的平均去除率分别为93.1%、84.9%、70.8%。缩短50%HRT(厌氧/缺氧3 h+好氧3 h)后,双级反应器总氮去除率提升到81.7%。16S rRNA高通量测序结果显示,聚糖菌Candidatus Competibacter的相对丰度在塑料填料表面上升了30.43倍(0.46%→14%),而在沸石颗粒表面上升了14.35倍(0.46%→6.60%),表明塑料填料表面更有利于聚糖菌的富集。

木醋液改性沸石吸附制革废水Cr^(3+)的应用研究

对用木醋液改性沸石处理制革含铬废水进行了应用试验研究,对改性沸石用量、废水p H值、处理时间,除铬效果等因素的影响,进行了试验,结果表明:当废水pH≥4, Cr^(3+)≤300 mg/L时,按铬与改性沸石量比1∶500投加改性沸石进行处理,铬去除率大于99%,污水可达排放标准。

粉煤灰沸石的改性及其在水处理中的应用进展

粉煤灰是一种细小的颗粒固体废弃物,处理不当会造成环境危害且影响人类健康。利用粉煤灰生产沸石是一种高值化利用方式,既解决了一部分粉煤灰处置问题,同时也增加了一种新型“以废治废”的环保材料。通过对近年来有关粉煤灰沸石的相关文献进行总结梳理,简述了粉煤灰与沸石的特征及粉煤灰沸石的合成方法,重点介绍了粉煤灰沸石的几种改性方法及其机理,如阳离子表面活性剂改性、离子交换改性和磁改性等。同时介绍了粉煤灰沸石作为吸附剂、催化剂载体在水处理中的应用,并对粉煤灰沸石改性及其在水处理中应用的发展方向提出了建议。

钢铁厂含铬废水污泥的处理工艺研究

为进一步提升钢铁厂含铬废水及污泥的处理效率和质量,基于某钢铁厂冷轧车间的含铬废水展开研究,采用沉淀法对废水中的铬离子进行有效处理,而后将沉淀法处理中产生的含铬污泥采用高温分解法做进一步深度处理。以上两个步骤完成后,含铬废水的整体污染去除率超过90%,效果较为显著,且其相关经济指标也较为优异。此次设计的钢铁厂含铬废水污泥处理工艺将为今后类似工作提供一定的参考借鉴,从而进一步提升含铬化合物处理效率和质量。

煤矸石制备混晶型分子筛及其吸附铜锌离子性能研究

以内蒙古准格尔地区某典型煤矸石为研究对象,采用碱熔-水热法制备了NaX/NaP混晶型分子筛,采用X射线衍射(XRD)、红外光谱(FTIR)、扫描电镜(SEM)等表征手段对分子筛进行了分析,系统研究了初始质量浓度、吸附温度、吸附时间、分子筛投加量等因素对NaX/NaP混晶型分子筛吸附水中Cu^(2+)、Zn^(2+)性能的影响规律,结果表明:NaX/NaP混晶型分子筛对Cu^(2+)、Zn^(2+)的吸附过程符合Langmuir等温吸附模型,对Cu^(2+)的饱和吸附容量为118.68 mg/g,对Zn^(2+)的饱和吸附容量为127.86 mg/g;混晶型分子筛对Cu^(2+)、Zn^(2+)的吸附符合准二级吸附动力学,吸附过程为扩散过程;煤矸石基分子筛对重金属离子表现出了良好的吸附效果,可用于重金属废水治理,从而实现煤矸石的高值化利用。

Fe_(3)O_(4)及Fe_(3)O_(4)@HA处理废水的应用研究

采用绿绣水浴转化方法制备了四氧化三铁(Fe_(3)O_(4))及掺杂腐植酸(HA)的Fe_(3)O_(4)@HA,并对其进行了红外和扫描电镜表征;研究了Fe_(3)O_(4)及Fe_(3)O_(4)@HA对废水中腐植酸、铬离子以及镍离子的去除效果,考察了Fe 0和Fe^(2+)的协同作用影响。结果表明:①Fe_(3)O_(4)@HA中腐植酸特征吸收峰突出,且其颗粒粒径在50~100 nm分散性好,表明腐植酸成功掺杂入Fe_(3)O_(4)结构中;②Fe_(3)O_(4)中掺杂HA后,对重金属去除效果显著增强,投加量均为2000 mg/L,重金属初始浓度均为40 mg/L时,对Cr(Ⅵ)去除率从24.5%提升到48.3%,Ni(Ⅱ)去除率从44.0%提升到86.3%;③Fe 0和Fe^(2+)组成的活性铁体系对采用Fe_(3)O_(4)或Fe_(3)O_(4)@HA吸附处理腐植酸、Cr(Ⅵ)和Ni(Ⅱ)的协同强化作用显著,对污染物的去除率最高达98.5%,去除效率提高最高达3倍。

用沸石处理含铬废水的试验研究

对用沸石处理含铬废水进行了试验研究，探讨了沸石用量、废水酸度、接触时间等因素对除铬效果的影响，结果表明：当废水ｐＨ≥４，Ｃｒ３＋≤３００ｇｍ／Ｌ时，按铬与沸石量比１∶５００投加沸石进行处理，铬去除率大于９９％，出水可达排放标准。