The use of toxic solid waste for the adsorption of dyes from waste streams

The use of chromium‐containing toxic solid wastes from the leather industry for the removal of dyes from waste‐waters has been studied. A batch adsorption model has been employed and the role of various experimental parameters on the efficiency of the process evaluated. The extent of dye removal was studied by varying parameters such as pH, contact time, initial concentration of the dye and amount of adsorbent. The experimental equilibrium data for this system has been analyzed using the linearized forms of Langmuir and Freundlich isotherms. The Langmuir isotherm was found to provide the best theoretical correlation of the experimental data and the adsorption was found to follow pseudo‐second‐order kinetics. The dye adsorbed solid wastes were used for the preparation of pigments. In essence, this study provides a greener solution for chromium‐containing solid wastes, dye containing waste‐waters and dye‐adsorbed chromium solid wastes. Copyright © 2007 Society of Chemical Industry     

Treatment of laundry waste‐water by electrocoagulation

BACKGROUND: The present study describes an electrocoagulation process for treating laundry waste‐water using aluminum plates. The effect of various parameters such pH, voltage, hydraulic retention time (HRT), and number of aluminum plates between the anode and cathode on efficiency of treatment are investigated. RESULTS: Experimental results showed that by increasing HRT, treatment efficiency increases but beyond 45 min changes are negligible. Among the results for chemical oxygen demand (COD), phosphorus, detergent, colour and turbidity, the lowest decrease was found for phosphorus. The larger the HRT, the greater the electrical current needed to achieve constant voltage and temperature in the system. The pH of the influent is a very significant variable which affects the treatment of laundry waste‐water considerably, the optimal range being 6.0–8.0. In addition, it was found that the pH increases from 8.3 to more than 10 over the first hour of treatment after which the pH remains relatively constant. Finally, kinetic analysis indicates that the adsorption system obeys a second‐order kinetic model. CONCLUSION: The aluminum hydroxide generated in the cell decreases the concentration of pollutants in laundry waste‐water to a permissible level. It is concluded that, compared with other treatment processes, electrocoagulation is more effective in treating laundry waste‐water under appropriate conditions. Copyright © 2011 Society of Chemical Industry     

Treatment of an industrial chemical waste‐water using a granular activated carbon adsorption‐microwave regeneration process

BACKGROUND: Industrial waste‐water is posing an ever‐greater environmental hazard. Recently, a process for purification combining activated carbon adsorption and microwave regeneration has drawn much attention. In this study, the effectiveness of this process for the treatment of industrial waste‐water from a chemical plant was tested. RESULTS: The effects of various factors including solution pH, granular activated carbon (GAC) dosage and contact time on the adsorption efficiency of organic compounds were studied. The regeneration of the exhausted GAC under microwave radiation was investigated, and the optimal conditions were: microwave power 400 W, radiation time 3 min for 10 g GAC. Under the optimal conditions the regenerated GAC recovered 97.6% of its original adsorption capacity. Repetitive uses of the GAC showed that it maintained a stable performance in the first few repetitions, but a decrease was observed after further repetitions. A GAC weight loss of about 10% at the sixth repetition was observed and a decrease in the surface area and increase in the surface basicity were observed for the regenerated GAC. Economic evaluation of the microwave regeneration process suggested that the total cost was about 24.3% of the GAC price at a pilot scale. CONCLUSIONS: A satisfactory regeneration of the chemical waste‐water exhausted GAC could be achieved under microwave radiation. The GAC adsorption‐microwave regeneration process was applicable for the treatment of this chemical waste‐water. Copyright © 2012 Society of Chemical Industry     

Stabilized protein waste as a source for removal of color from wastewaters

Seeking solution to pollution problems is a prime concern of many researchers today. The waste from one industry can be judiciously used to treat another waste. This concept has been used in this study, wherein, the fleshing, a solid waste (biopolymer) emanating from leather industry has been used as an adsorbent for removal of dyes from wastewater. Fleshing has been crosslinked with glutaraldehyde to stabilize it against degradation. The various parameters like effect of pH, role of salt concentration, adsorbent dosage, and initial concentration of dye have been standardized. About 90% dye removal has been achieved by treating 100 mg/L dye solution with 12 g/L of glutaraldehyde‐crosslinked fleshing. The dye removal has been found to follow Langmuir type of adsorption isotherm. The optimized parameters of batch adsorption studies have been applied to treat sectional wastewater from a commercial tannery. The study also explores the possibility of reusing the dye loaded fleshing as a reductant in the manufacture of a tanning salt, which is used in leather industry for tanning of leathers. Thus, a holistic solution to both solid and liquid waste has been presented in this work. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

拆解固体废弃物资源化利用及环境影响研究

随着经济的全球化发展和环境治理工作的需要,各国开始研究再生资源的利用工作。近几年,固体废弃物拆解与利用工作得到了一定发展,大大提高了再生资源利用率。分析了某地区废弃物拆解行业的现状及其对经济、社会、资源环境产生的效益,论述了拆解行业给环境带来的影响。     

Recent developments of metal oxide semiconductors as photocatalysts in advanced oxidation processes (AOPs) for treatment of dye waste‐water

The textile industry presents a global pollution problem owing to the dumping or accidental discharge of dye waste‐water into waterways, which is having a major impact on the quality and aesthetics of water resources. The World Bank estimates that 17 to 20% of industrial water pollution comes from textile dyeing and treatment. This percentage represents an appalling environmental challenge for clothing designers and other textile manufacturers. Recently, the application of metal oxide semiconductors in the advanced oxidation process (AOP) has gained wide interest for the treatment of dye waste‐water owing to its good degradation efficiency, low toxicity and physical and chemical properties. AOP refers to a set of chemical treatment procedures designed to remove organic and inorganic materials from waste‐water by oxidation. In this paper, recently developed metal oxide semiconductors are discussed, in which the semiconductors are generally divided into three categories: (i) titanium dioxide; (ii) zinc oxide; and (iii) other metal oxides (such as vanadium oxide, tungsten oxide, molybdenum oxide, indium oxide and cerium oxide). The syntheses and modification methods as well as the efficiency of each category are discussed and analyzed. Copyright © 2011 Society of Chemical Industry     

机械加工中含油废水处理工艺的研究

研究了活性炭对机械加工中含油废水处理工艺。探讨了在不同吸附条件下（吸附剂量、时间、pH）的吸附效果。结果表明,活性炭吸附的最佳工艺条件是：含油120 mg/L的10 mL废水中,加入活性炭质量0.3 g,加热搅拌时间60 min,pH值为8。在最佳条件下,含油废水在活性炭吸附后的COD为160 mg/L。     

Utilization of polyampholyte hydrogels for simultaneous removal of textile dyes from aqueous solutions

The study aimed to create hydrogel structures with greater functionality, otherwise known as polyampholytes (PAHs), and to use these in simultaneous removal studies for remazol-type dyes found in environmental waste waters. Adsorption studies were accomplished at 20°C and 35°C, indicated that adsorption process was exothermic in nature. The Q_m values for the PAH-dye systems were in the interval 111–122 mg dye/g PAH with Ads% from 94% to 98%. The ability of PAH hydrogels to adsorb two different species of dye molecules at the same time is an advantage of PAH adsorbents compared to other hydrogel adsorbents prepared in this area.     

吸附法处理含汞废水装置运行小结

介绍了新疆天业（集团）有限公司采用吸附法工业试验装置处理含汞废水的工艺,并对装置运行过程中出现的问题进行了改造。改造后,系统运行稳定,出水含汞质量浓度小于0．005mg／L,达到国家排放标准。     

城市生活垃圾成分及其波动对水泥窑的影响分析

就水泥窑处置生活垃圾时,垃圾灰渣成分及其波动对熟料质量的影响进行了分析研究,结果表明:生活垃圾焚烧产生的灰渣可以作为水泥替代原料;垃圾灰渣作为替代原料会带入一些干扰元素,为保证垃圾处置量及熟料质量,需要对垃圾进行均化等处理。     

Contributions of electrochemical oxidation to waste‐water treatment: fundamentals and review of applications

OVERVIEW: This paper provides an overview of some fundamental aspects of electrochemical oxidation and gives updated information on the application of this technology to waste‐water treatment. In recent years, electrochemical oxidation has gained increasing interest due to its outstanding technical characteristics for eliminating a wide variety of pollutants normally present in waste‐waters such as refractory organic matter, nitrogen species and microorganisms. IMPACT: The strict disposal limits and health quality standards set by legislation may be met by applying electrochemical oxidation. However, treatment costs have to be cut down before full‐scale application of this technology. Deployment of electrochemical oxidation in combination with other technologies and the use of renewable sources to power this process are two steps in this direction. APPLICATIONS: Effluents from landfill and a wide diversity of industrial effluents including the agro‐industry, chemical, textile, tannery and food industry, have been effectively treated by this technology. Its high efficiency together with its disinfection capabilities makes electro‐oxidation a suitable technology for water reuse programs. Copyright © 2009 Society of Chemical Industry     

改性污泥处理含铍废水的吸附特性研究

提出了用改性污泥处理含铍废水的新方法,解决了含铍废水达标难的问题。研究了铍在改性污泥上的吸附平衡和吸附动力学,考察了温度、pH对吸附过程的影响。结果表明:铍在改性污泥上的吸附等温线数据可用Fruendlich方程描述,而不能用Langmuir方程描述;铍的吸附过程遵循二级吸附动力学模型,也能用Lagergren一级速率方程描述;温度对吸附结果影响不大,pH为吸附过程的主要影响因素。     

Electrochemical degradation of pulp and paper industry waste‐water

BACKGROUND: Conventional biological waste‐water treatment techniques are insufficient to degrade large quantities of dissolved lignin discharged by small‐scale paper mills. The current investigation is aimed at comparing the overall performance of basic electrochemical reactor configurations such as batch, batch recirculation, recycle and single pass systems, in removing the organic part of waste‐water from a small‐scale, agro‐based paper industry. The effect of current density, supporting electrolyte concentration, duration of electrolysis, specific electrode surface and fluid flow rate on the removal of pollutants and energy consumption are critically evaluated. The improvement in biodegradability of the effluent during treatment is also noticed. RESULTS: The batch recirculation mode of operation was found to be superior in comparison with a batch system using the same specific electrode surface for both COD removal (73.3 vs. 64%) and capacity utilization (rate constant 1.112 × 10^?3 vs. 1.049 × 10^?3 cm s^?1). The pollutant removal performance of the batch recirculation system improved considerably with increase in the circulation flow rate. At the best operating point in the recycle system, 59% of COD was removed, corresponding to a current efficiency of 68.9% and specific energy consumption of 18.46 kWh kg^?1. The biodegradability index of the waste‐water was improved from 0.18 ± 0.01 to 0.36 ± 0.01. CONCLUSION: A recycle reactor was the best configuration, because of its flexibility of operation. Circulation flow rate and withdrawal flow rate enable the control of transfer coefficients and treatment duration respectively. Electrochemical treatment not only removes the bulk of the organic matter, but also makes the remaining pollutants more easily biodegradable. Copyright © 2009 Society of Chemical Industry     

Pilot‐scale treatment of waste‐water from carbon production by a combined physical–chemical process

BACKGROUND: Due to its strong colour, high concentrations of fluorides and chemical oxygen demand (COD_Cr) and large amount of suspended solids (SS), the waste‐water from carbon production (WCP) seriously affects the stability of the circulating system of Guizhou Branch, Aluminium Corporation of China. In this paper, the performance of a pilot‐scale (24 m³ d^?1) combined treatment plant, consisting of chemical precipitation, coagulation, and Fenton oxidation, for the treatment of WCP was investigated. RESULTS: Lime precipitation and hydrated ferrous sulphate (HFS) coagulation, with polyacrylamide (PAM) as a coagulation aid, proved to be effective in the removal of colour (>70%), suspended solids (SS) (>90%) and fluoride (>80%) from the WCP. Subsequent Fenton oxidation combined with coagulation as a final treatment efficiently removed SS, F^?, COD_Cr, dissolved organic carbon (DOC) and colour. The average total removal efficiencies of these parameters in the pilot‐scale combined technology were as follows: SS = 98.8%, F^? = 95.7%, COD_Cr = 94.8%, DOC = 91.8% and colour = 98.3%, giving an average effluent quality: colour 24 (multiple), COD_Cr 168 mg L^?1, DOC 80 mg L^?1, F^? 38 mg L^?1 and SS 44 mg L^?1, consistent with the reusable water limits for the process. CONCLUSIONS: The current experimental results and the economic evaluation suggest that the combined process could be advantageous and feasible for the treatment of WCP. Copyright © 2009 Society of Chemical Industry     

Treatment of dyehouse waste‐water by supercritical water oxidation: a case study

BACKGROUND: Supercritical water oxidation (SCWO) of dyehouse waste‐water containing several organic pollutants has been studied. The removal of these organic components with unknown proportions is considered in terms of total organic carbon concentration (TOC), with an initial value of 856.9 mg L^?1. Oxidation reactions were performed using diluted hydrogen peroxide. The reaction conditions ranged between temperatures of 400–600 °C and residence times of 8–16 s under 25 MPa of pressure. RESULTS: TOC removal efficiencies using SCWO and hydrothermal decomposition were between 92.0 and 100% and 6.6 and 93.8%, respectively. An overall reaction rate, which consists of hydrothermal decomposition and the oxidation reaction, was determined for the hydrothermal decomposition of the waste‐water with an activation energy of 104.12 ( ± 2.6) kJ mol^?1 and a pre‐exponential factor of 1.59( ± 0.5) × 10⁵ s^?1. The oxidation reaction rate orders for the TOC and the oxidant were 1.169 ( ± 0.3) and 0.075 ( ± 0.04) with activation energies of 18.194 ( ± 1.09) kJ mol^?1, and pre‐exponential factor of 5.181 ( ± 1.3) L^0.244 mmol^?0.244 s^?1 at the 95% confidence level. CONCLUSION: Results demonstrate that the SCWO process decreased TOC content by up to 100% in residence times between 8 and 16 s under various reaction conditions. The treatment efficiency increased remarkably with increasing temperature and the presence of excess oxygen in the reaction medium. Color of the waste‐water was removed completely at temperatures of 450 °C and above. Copyright © 2010 Society of Chemical Industry     

垃圾焚烧厂渗滤液生化出水混凝处理及其模型的建立

对采用聚合氯化铝、硫酸铝和氯化铁等混凝剂处理焚烧厂垃圾渗滤液生化出水的混凝效果及其模型进行了研究.结果表明:聚合氯化铝对焚烧厂垃圾渗滤液中CODCr、色度和浊度的去除效果比硫酸铝和氯化铁要好,且投加量相对也较少.在投加量500 mg/L、中性条件下,CODCr、浊度和色度的去除率可分别达到28.9%、91.6%和77.6%.在不同投药量、pH和搅拌速度下,PAC保持了良好的污染物去除效果,而对硫酸铝和氯化铁的处理效果影响较大.各种混凝剂的最佳投药量与起始CODCr浓度之间的关系可采用指数关系式表达.通过对PAC在各条件下混凝效果的统计分析,采用Matlab优化工具软件,建立了垃圾焚烧厂垃圾渗滤液PAC混凝处理的处理效果数学模式方程,其与试验结果的相关系数可达到0.982,表明建立的模型与混凝处理效果较为一致.     

基于酸改性的半焦对染料废水的吸附性能研究

为制备高效吸附材料,采用化学活化法对延安子长煤低温热解的半焦进行改性,并进行X射线衍射(XRD)、N2等温吸附、扫描电子显微镜(SEM)表征。以罗丹明B、酸性品红为目标物,采用吸附剂添加量、溶液p H、吸附时间等为考察参数,研究了酸改性半焦对罗丹明B、酸性品红模拟染料废水的吸附性能,探索了酸改性半焦对罗丹明B、酸性品红的吸附动力学行为。结果表明:改性半焦对2种染料有良好的吸附性能,准二级动力学模型的相关系数在0.999以上,模型饱和吸附量与实验值相近,很好地描述了2种染料在酸改性半焦上的吸附行为。