Examination of the Level of Heavy Metals in Wastewater of Bandar Abbas Wastewater Treatment Plant

One of the main environmental pollutants is heavy metals. Due to extensive usage in industry, these metals enter biological cycle rapidly and contaminated water and soil resources rapidly. In this work, lead, copper, zinc and chromium of Bandar Abbas wastewater are examined. For this research, nine stations were set for measurement in urban level in Bandar Abbas and sampling of aforesaid metals was performed in fall and winter 2006 in these stations. After extraction and preparation operations using APDC-MIBK, samples were measured using flame atomic absorption system. According to results, concentrate of studied metals was lower than allowable standard value set by Iran environmental protection organization for agricultural purposes and sewage to ground level waters. In addition, efficiency of Bandar Abbas wastewater treatment plant to remove these metals is 40% - 70% from which highest removal is for zinc as much as 71.1% and lowest level is for copper as much as 40.5%. However, copper level was higher than allowable level for agricultural purposes in spring and summer (0.21 mg/L and 0.23 mg/L, respectively) and lower in fall and winter (0.103 mg/L and 0.098 mg/L, respectively). Furthermore, changes in concentration of metals in these stations in various seasons were measured and analyzed using one-way variance analysis and simultaneous effects of time and place on measured variables were analyzed using two-way variance analysis.

Treatment of Wastewater Containing Heavy Metals Using Dissolved Air Released Flotation Column

A new type of dissolved air released flotation column is developed to treat wastewater containing Cr(VI)based on advantages of both dissolved air floatation and column floatation. By using a column with a diameter of 50mm and a specially made dissolved air releaser, micro-bubbles inside the column can be formed. N2H4·H2O was usedas reductant, AlCl3 as flocculant, C12H25SO3Na(SDS) as surfactant in the experiment. The effects of pH of wastewa-ter, pressure of dissolved air, ratio of return water, and concentration of flocculant and surfactant on the removal effi-ciency are studied. The results show that the efficiency of dissolved air released flotation column is much higher thanthat of other approaches after the operation parameters are optimized, with the reduction ratio of Cr(VI) in wastewaterreaching 98%. So this technique can be widely used in wastewater treatment.

Two-stage treatment process of pickling wastewater in the cold-rolling production of stainless steel

Based on the characteristics of pickling wastewater in the cold-rolling production of stainless steel, a new processing route, featuring source sludge reduction, wastewater two-stage treatment, heavy metal-contained sludge and calcium salt sludge separating recovery, was proposed. As shown by the research results, after the two-stage process treatment, the effluent water can steadily reach the emission standards, the sludge yield can be decreased by more than 8% ; within the heavy metal-contained sludge, the recovery rates of Fc,Cr and Ni can either reach or surpass 95% ,and the total content ofF and S can drop to around 3%. Therefore,the sludge in the front part can be used as ferric dust. In the calcium salt sludge ,the recovery rate of F can either reach or surpass 85% ,and the total contents of Fe,Cr and Ni can fall below 0.5%. So the sludge in the rear part can be used as fluorgypsum or fluorite. Meanwhile,the results of the analysis on heavy metals leaching toxicity and morphologic distribution indicate that the two kinds of sectionalized sludge are not classified as hazardous wastes, which have a stable behavior and better utilization values compared with the former mixed- sludge.

Removal of Heavy Metal Ions from Wastewater by Using Biosorbents from Marine Algae-A Cost Effective New Technology

Heavy metal pollution from industrial wastewater is a worldwide environmental issue. Biosorption of heavy metals by using biosorbents derived from various types of biomass has been shown to be effective for the uptake of heavy metal ions. In this study, biosorbents derived from the biomass of a group of marine macroalgae were used for the removal and recovery of heavy metal ions from aqueous solutions. Results indicated that the biosorbents have high uptake capacities and affinities for a number of heavy metal ions. The uptake capacities of the biosorbents were in the range of 1.0 to 1.5mmol·g-1 for divalent heavy metal ions. The kinetics of the uptake process was fast and the process can be used in both batch and fixed-bed operations. It appears that the biosorption process by using biosorbents from marine macroalgae can be an efficient and cost effective technology for the treatment of heavy metal containing wastewater.

Removal of Some Heavy Metals from Wastewater by Using of Fava Beans

The Fava Beans were used in this work as low cost adsorbent material for removal of Pb(II), Cd(II) and Zn(II) ions from aqueous solutions. The samples were prepared without farther treatment and sorted according to the particles diameter by standard sieves 250 - 500 μm. Batch adsorption experiments were carried out to study the adsorption process, several parameters such as Initial pH of adsorbent, effect of contact time, effect of adsorbent amount and effect of metal concentration were conducted in these experiments. The effects of any one of those previously mentioned parameters on the adsorption capacity were studied while the other parameters were kept constant. It was found that the obtained maximum adsorption capacities of Fave beans for the removal of selected heavy metals were very high. This provide us to use Fava beans as a low coast adsorbent material to clean up the water in the environment from toxic heavy metals such as Pb(II), Cd(II) and Zn(II) ions.

Phytoremediation of urban wastewater by model wetlands with ornamental hydrophytes

Phytoremediation offers a cost-effective, non-intrusive, and safe alternative to conventional cleanup techniques. In this study, we used ornamental hydrophytes plants as constructed wetlands to treat urban or rural domestic wastewater. Most ornamental hydrophytes adapted to the wastewater well, and were fairly efficient in scavenging BOD5 （biological oxygen demand 5 d）, COD （chemical oxygen demand）, TN （total nitrogen）, TP （total phosphorus） and heavy metals （Cr, Pb, Cd） in the wastewater. However, the efficiency varied a lot for various species to different contaminants, Iris pseudacorus L. and Acorus gramineus Soland were good choices for treatment of composite-polluted urban wastewater. Some variation in the change of membrane peroxidation and endogenous protective system in responses to wastewater was found among six hydrophytes, which have a correlation with the efficiency of wastewater treatment. It may demonstrate that the developed antioxidative systems of L pseudacorus and A. gramineus contributed much to their superiority. On the other hand, interaction of different components in the wastewater might have certain effects on phytoremediation.

10 Towards a Safer Environment:(7)How apatite minerals remediate Pb,Zn and Mn from wastewater?

To evaluate the effectiveness of apatite mineral in removing different contaminants from low quality water in the industrial city of abha,Asir region,southwestern of Saudi Arabia two phosphatic clay dominated by apatite mineral were selected.In situ remediation experiment proved that apatite mineral has the highest affinity for Pb and removed more than 94% from initial Pb concentration.The rest of contaminants followed the descending order of:Zn>Mn>Cu>Co>Ni.The sorption of Pb,Zn and Mn onto apatite mineral was well characterized by the Langmuir model.Ternary-metal addition induced competitive sorption among the three metals,with the interfering effect of Pb>Zn>Mn.During metal retention by apatite mineral calcium and phosphate were determined in equilibrium solution.Calcium increased and phosphate decreased with increasing metal disappearance.The greatest increase of calcium and the largest phosphate reduction were found with Pb+2 sorption. This is suggested that Pb+2 retention by apatite was through the dissolution of apatite which mean release of Ca and P into solution and formation of pyromorphite(lead phosphate)as consuming of P.Obtained results suggested that there are two general mechanisms for the ability of apatite mineral to take up Pb2+,Zn+2 and Mn+2.The first is (ion-ion exchange mechanism)concerned with adsorption of ions on the solid surface followed by their diffusion into apatite mineral and the release of cations originally contained within apatite.The second is (dissolution- precipitation mechanism)concerned to the dissolution of apatite in the aqueous solution containing Pb2+,Zn+2 and Mn+2 followed by the precipitation or coprecipitation.Pb+2 desorption responding to solution pH may indicate that not all the Pb+2 was chemisorbed and fraction of Pb+2 was weakly adsorbed or complexed on the surface of apatite mineral.

Magnesium oxide(MgO)nanoadsorbents in wastewater treatment:A comprehensive review

Wastewater contamination by heavy metals and synthetic dyes presents a significant environmental challenge,necessitating effective and sustainable separation techniques.This review article provides a detailed examination of magnesium oxide(MgO)nanoparticles as an innovative nanoadsorbent for wastewater treatment,with a specific focus on heavy metal and dye removal.The review comprehensively explores various aspects of MgO nanoparticles,including their structural characteristics and synthesis techniques.The article delves into the morphology and crystallographic arrangement of MgO nanoparticles,offering insights into their structural attributes.Given the complexity of adsorption processes,the review identifies and analyzes parameters influencing the adsorption efficiency of MgO nanoparticles,such as temperature,pH,contact time,initial concentration,and co-existing ions.The interplay between these parameters and the adsorption capability of MgO nanoparticles emphasizes the importance of optimizing operational conditions.Furthermore,the review assesses various synthesis methods for MgO nanoparticles,including sol-gel,hydrothermal,precipitation,green synthesis,solvothermal,and template-assisted techniques.It discusses the advantages,limitations,and resulting nanoparticle characteristics of each method,enabling readers to grasp the implications of synthesis processes on adsorption efficiency.This comprehensive review consolidates current insights into the effectiveness of MgO nanoparticles as a potent nanoadsorbent for removing heavy metals and dyes from wastewater covering a wide spectrum of aspects related to MgO nanoparticles.Moreover,there is a need to investigate the use of MgO in the treatment of actual wastewater or river water,in order to leverage its cost-effectiveness and high efficiency for practical water treatment applications in real-time.

电吸附处理重金属离子的研究进展

从电吸附技术的基本原理入手,总结了电吸附处理Cu2+、Pb2+、Cr6+、Cd2+等重金属离子的研究进展,对电吸附处理重金属的未来进行了展望,指出了电吸附处理重金属离子研究目前存在的一些缺陷,并提出了电吸附处理重金属离子走向工业化需要解决的问题。

危险废物处置中心重金属废水处理研究

危险废物处置中心的废水中含有很多重金属离子,主要成分包括铬、铅、汞、砷等,如果不对这些重金属离子进行及时处理,这些污染物就会对环境产生不利的影响。本文针对某危险废物处置中心重金属废水的特点,采用“调节池+絮凝沉淀+A/O工艺+MBR+NF+RO”工艺开展了对重金属废水的处理试验研究,并验证其处理效果。实践证明这种处理技术在重金属废水处理中有良好的应用前景。

秸秆生物质炭处理重金属废水研究现状及展望

秸秆生物质炭作为一种新型吸附剂,具有原料丰富、可再生、低成本等优势,在重金属废水处理领域具有广阔的应用前景。本文综述了秸秆生物质炭材料制备,分析了秸秆生物质炭对重金属吸附机制,讨论了秸秆生物质炭在重金属废水处理中的应用,并结合生物质炭材料的制备和应用中存在的问题,提出吸附机理、吸附容量和再生性能等有待进一步深入研究的展望。该综述加深了对重金属废水处理中秸秆生物质炭的作用机制的科学认识,为秸杆生物质炭材料的开发及其在重金属废水净化领域的应用提供了重要参考。

含Mn(Ⅱ)/Mn(Ⅶ)废水处理技术研究进展

阐述了含锰废水的来源及危害,以Mn(Ⅱ)和Mn(Ⅶ)为研究对象,从化学、物理化学、生物处理及多技术耦合处理四个方面,详述了目前国内外对含Mn(Ⅱ)废水处理技术的研究现状;并概述了吸附法和螯合絮凝法对Mn(Ⅶ)的去除性能及发展趋势。对各种除锰技术的优缺点进行对比分析,并对含锰废水处理技术的发展前景作出展望。

层状复合氢氧化物的结构调控及其吸附重金属离子的研究进展

层状复合氢氧化物(LDHs)是具有特殊层状结构的阴离子黏土,具有化学组成可调、比表面积大及结构记忆效应独特等性质,在废水处理方面备受关注。调控LDHs自身结构,是进一步扩大其应用范围、提高其吸附性能的有效途径。该文介绍了LDHs特殊的层状结构和其自身性质;总结了LDHs最常用的制备方法,即共沉淀法、离子交换法、尿素水解法、煅烧复原法和溶胶-凝胶法等,分别介绍了各种制备方法的原理和特点;综述了LDHs的结构调控对其吸附重金属离子性能的影响,并总结了LDHs对重金属离子的吸附机理;最后,指出了目前LDHs在处理含有重金属离子废水研究中面临的挑战,并对该材料未来的研究方向和发展趋势进行了展望。

山竹皮吸附剂对铜离子的吸附行为及其燃烧特性研究

以山竹果皮渣为原料,经过异丙醇脱色、碱性试剂活化制备出吸附材料,用于吸附溶液中的铜离子。实验结果表明,pH值升高有利于山竹皮吸附剂吸附铜离子,最大吸附容量达1.5 molCu^(2+)/kg,且30 min内可达到吸附平衡。负载铜离子数量对吸附剂燃烧热分解的特征温度有显著影响,铜离子浓度低于2 mmol/L时,负载的铜离子数量增加,其开始热分解以及剧烈燃烧分解的温度点显著降低;铜离子浓度高于2 mmol/L后,其热分解温度特征值不再发生明显变化。铜离子在燃烧过程中扮演催化剂的作用,能有效促进燃烧反应。

锌冶炼废水中锌稳定达标工艺探讨

在锌冶炼废水处理过程中,重金属锌的稳定达标对促进整个外排水稳定达标排放非常重要。西北铅锌冶炼厂水处理车间净化工序主要采用两段石灰乳中和、加酸回调pH值来确保废水处理后达标排放。然而在实际操作过程中发现,很难将Zn稳定控制在1.5 mg/L内。根据多年生产实践,从操作角度出发,分析说明确保锌冶炼废水处理过程中Zn稳定达标排放的影响因素及有效途径。

钙铝层状双氢氧化物(CaAl-LDH)对铅镉砷污染废水的吸附性能及机制研究

重金属污染普遍存在且日趋严重,解决阳离子和阴离子重金属共存的复合污染问题依然是一个严峻的挑战。本研究采用简便的原位共沉淀法制备了钙铝层状双氢氧化物(CaAl-LDH),用于去除水中的重金属离子。通过XRD、SEM、FTIR和XPS等表征方法研究CaAl-LDH的制备及其对重金属离子的吸附机理。采用批吸附实验研究CaAl-LDH对Pb(Ⅱ)、Cd(Ⅱ)和As(Ⅴ)三种金属离子的吸附能力。结果表明,准一级动力学模型可以很好地拟合CaAl-LDH对三种重金属的吸附。吸附等温线结果表明,与Freundlich模型(R^(2)<0.67)相比,Cd的吸附过程更符合Langmuir模型(R^(2)>0.92)。Langmuir和Freundlich模型都能有效拟合Pb和As的吸附(R^(2)>0.90)。CaAl-LDH对Pb(Ⅱ)、Cd(Ⅱ)和As(Ⅴ)的最大吸附量分别为786.6、437.2和72.9 mg/g,并且在10 min内能够达到吸附平衡,反应快速高效。CaAl-LDH对铅、镉、砷的吸附机理各异。铅的吸附可能通过表面沉淀实现,而镉的吸附机理为同晶置换。至于As的吸附,可能涉及LDH层间的离子交换。该实验提供了一种对阴、阳离子重金属都具有高效吸附性能的LDH材料,并在重金属复合污染废水治理中显示出一定的应用潜力。

工业园区重金属污染废水处理技术研究

针对工业园区重金属污染问题,文章提出了新的工业园区重金属污染废水处理技术。预处理阶段,向废水中加入碱性药剂和混凝剂,使大颗粒重金属污染物实现碱性化学沉淀。随后,运用界面渐进间接冷冻法,借助异相成核原理,将废水转化为重金属污染杂质结晶和纯冰结晶。通过调整环境温度,得到冰结晶和重金属污染浓缩液,再经离心机冷冻分离,完成废水处理。实验证明,此技术在处理锌酸盐镀锌工艺废水时,Zn^(2+)和OH^(-)去除率分别高达78.7%和67.2%,显示出优异的处理效果。该技术为工业园区重金属污染问题提供了新的解决方案。

电镀废水处理技术研究进展

电镀废水中含有大量有害物质,若不经处理直接排放,则会危害生态系统以及人类的身体健康。综述电镀废水的来源、危害以及电镀废水处理技术,重点阐述化学法、物理法、物理化学法、生物法在处理电镀废水过程中的应用情况,并对未来电镀废水的处理技术进行展望。

某电子信息产业园废水处理工程实例

针对某电子信息产业园企业排放废水水质差异大,成分复杂的特点,将废水分类收集,通过采用中和、混凝沉淀、化学氧化及生化处理组合工艺,出水水质达到GB 39731—2020《电子工业水污染物排放标准》表1中的间接排放标准及GB/T 31962—2015《污水排入城镇下水道水质标准》表1中B级标准及下游污水处理厂接管标准。介绍了该工程的工艺流程、主要设计参数、投资运行成本及工程运行情况。

工业水处理工艺优化与回用探讨

目前冶炼行业废水成分较为多样复杂,处理水的去向持续受到关注。文章介绍了某冶炼厂针对重金属离子的传统废水处理工艺以及改进后的废水处理工艺,并对当前存在的问题进行了分析,结合生产模式,提出了改进工艺的方法。结果表明:在当前生产条件下,不锈钢材质的设备更适用于生产废水处理回用。相比较水处理工艺1(污酸处理系统+深度处理系统),对水处理工艺2(化学法工艺)进行改进更为便利,且对提高循环水水质而言更高效便利,有利于促进废水的“零排放”,提高循环水质量。