Glycerol removal from biodiesel using membrane separation technology

Membrane separation technology was used to remove free glycerol from biodiesel in order to meet the ASTM D6751 and EN 14214 standards. Fatty acid methyl esters (FAME) produced from canola oil and methanol were purified using ultra-filtration. The effect of different materials present in the transesterification reaction, such as water, soap, and methanol, on the final free glycerol separation was studied. A modified polyacrylonitrile (PAN) membrane, with 100 kD molecular weight cut-off was used in all runs. Tests were performed at 25 °C and 552 kPa operating pressure. The free glycerol content in the feed, retentate and permeate of the membrane system was analyzed using gas chromatography according to ASTM D6584. Results showed low concentrations of water had a considerable effect in removing glycerol from the FAME even at approx. 0.08 mass%. This is four orders of magnitude less than the amount of water required in a conventional biodiesel purification process using water washing. It is suggested that the mechanism of separation of free glycerol from FAME was due to the removal of an ultrafine dispersed glycerol-rich phase present in the untreated FAME. This was confirmed by the presence of particulates in the untreated FAME. The size of the particles and the free glycerol separation both increased with increasing water content of the FAME. The trends of separation and particle size vs. water content in the FAME phase were very similar and exhibited a sudden increase at 0.08 mass% water in the untreated FAME. This supports the conclusion that water increased the size of the distributed glycerol phase in the untreated FAME leading to its separation by the ultra-filtration membrane. The technology for the removal of free glycerol from biodiesel was found to use 2.0 g of water per L of treated FAME (0.225 mass% water) vs. the current 10 L of water per L of treated FAME.     

膜技术对污水中病原微生物去除的研究进展

从公共卫生安全角度出发,分析了污水处理过程中可能存在的卫生学安全问题。综述了膜分离方法对细菌与病毒的去除机理,以及对病原微生物的去除效果,并对膜分离过程中存在的问题进行了初步分析,提出了在污水消毒方面应该注意和需要进一步研究解决的问题。     

Cationic starch for microalgae and total phosphorus removal from wastewater

The city of Logan, Utah treats wastewater in 460 acres of facultative lagoons. Naturally growing algae in these lagoons uptake nutrients and remediate the wastewater, but require coagulation and flocculation for separation from wastewater. Cationic corn starch and cationic potato starch with a degree of substitution 1.34 and 0.82, respectively, were synthesized using 3‐methacryloyl amino propyl trimethyl ammonium chloride and tested on Scenedesmus obliquus and lagoon wastewater. The zeta potential of the cationic starches tested over a pH range 5.0–10.0 showed an average of +16.0 and +15.1 mV for cationic corn starch and cationic potato starch, respectively. Total suspended solids removals of 90 and 85% were achieved with cationic corn starch and cationic potato starch, respectively, when tested with S. obliquus. Tests with wastewater showed total suspended solids removals of 80 and 60% for cationic corn starch and cationic potato starch, respectively. Total phosphorus removal values from wastewater were approximately 33, 29, and 42% for cationic corn starch, cationic potato starch, and alum, respectively, for a coagulant/algae ratio of 1.4 (wt/wt). These results indicate that cationic starch has the potential to replace alum for algae harvesting and wastewater treatment making it a suitable alternative to inorganic coagulants and flocculants. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2572–2578, 2013     

渗透汽化膜处理VOCs废水研究进展

本文着重介绍了渗透汽化分离技术的基本原理,分离膜材料的最新研究进展及影响渗透汽化分离操作的影响因素。最后对渗透汽化分离技术的工业应用提出了自己的见解。     

水解酶法回收木薯黄浆废水中的淀粉

以胰蛋白酶作为水解酶,采用水酶法从木薯黄浆废水中回收淀粉。通过调节酶加量、温度、时间、pH等因素,得到木薯淀粉的最佳回收条件:加酶量0.05 g/L,酶解时间3 h,酶解温度35℃,酶解pH值为8.5。在最佳条件下得到沉淀物质量为10.85 g/L,沉淀物中淀粉含量为80.4 g/100 g,粗淀粉质量为8.72 g/L。     

Decolourization and COD removal from reactive dye‐containing wastewater using sonophotocatalytic technology

Decolourization and COD removal from synthetic wastewater containing Reactive Brilliant Orange K‐R (RBOKR) dye using sonophotocatalytic technology was investigated. Experimental results showed that this hybrid technology could efficiently remove the colour and reduce COD from the synthetic dye‐containing wastewater, and that both processes followed pseudo first‐order kinetics. At the condition of 0.1 m³ h^?1 airflow, 0.75 g dm^?3 titanium dioxide and 0.5 mmol dm^?3 RBOKR solution, the rate constants of decolourization and COD removal were 0.0750 and 0.0143 min^?1 respectively for the sonophotocatalytic process; 0.0197 and 0.0046 min^?1 respectively for the photocatalytic process and 0.0005 and 0.0001 min^?1 respectively for the sonochemical process. The rate constants of sonophotocatalysis were greater than that of both the photocatalytic and sonochemical processes either in isolation or as a sum of the individual process, indicating an apparent synergetic effect between the photo‐ and sono‐processes. Copyright © 2003 Society of Chemical Industry     

脱除废水中挥发性有机化合物的渗透汽化复合膜研究进展

渗透汽化作为一种绿色、高效的膜分离技术,应用于废水中挥发性有机污染物的脱除方面具有显著的优势。本文介绍了渗透汽化技术的原理和特点,综述了目前通常采用的复合膜的特点、种类及其在挥发性有机物处理中的渗透汽化性能,并对渗透汽化复合膜的应用前景进行了展望。     

氨-水精馏技术在工业废水脱氨中的应用

将高效节能脱氨技术应用到工业废水脱氨过程,可将废水中的氨氮降至15×10-6以下,达到国家的综合污水排放标准(GB8978-96)中的Ⅰ级标准.脱氨过程不仅可以产生12%～18%的氨水;而且也能得到含量为90%以上高浓度氨气,用于反应制得铵盐,实现了资源循环利用.蒸汽消耗小于105kg/t(废水),单套装置的处理规模已达到600m3/d.     

Statistical optimization of chemical oxygen demand removal from wastewater by electrochemical oxidation

The independent and combined effects of four variables (current density, electrolyte concentration, air flow rate and pH) on COD removal from wastewater by electrochemical oxidation were optimized using 2⁴ full factorial experimental design. ANOVA was conducted to test the combined effects of the independent variables (the four control factors and time) on COD removal. To determine the reaction order of COD removal, 1^st, 2^nd or 3^rd reaction orders were considered; 1^st order kinetics showed the highest average r² value. The backward elimination regression method was used to determine the 1^st order k _COD equation, and main effects and 2-way interaction effects on the 1^st order equation were investigated. Using this equation, k _COD values for the 16 experimental conditions were predicted and COD values were calculated with respect to time. Finally, we tried to determine optimal operating conditions using color and COD removal as endpoints using the multiple response surface method.     

Phenol removal from wastewater using eco-friendly hybrid hydrogels

The intent of this study was to evaluate the ability of low-cost polyacrylamide/starch hybrid hydrogels in removing organic pollutants from wastewater, using phenol as a model compound, besides of investigating the adsorption/desorption behavior as a function of hydrogels composition. The results indicated that the hydrogel with the lowest amount of starch and crosslinking agent exhibited the maximum phenol adsorption capacity, 21 mg g⁻¹. The adsorption isotherm data were described by Langmuir and Freundlich adsorption isotherm models. According to linear regression analysis, the Freundlich isotherm model was the best fit among the isotherm models for the adsorption process. Furthermore, desorption study revealed a minimum of about 60% of phenol release, indicating reusability to wastewater treatment.     

含油废水的除油技术研究

用波纹板油水分离器处理含油废水,研究了影响除油率的几种因素,并考察了加设加压溶气气浮对除油率的影响.实验结果表明,当温度为30℃,进水流量为156 L/h,聚结板组为涂有涂料的镀锌板时,加设加压溶气气浮,除油率可达64%,与未加设加压溶气气浮相比,除油率可提高10%以上.     

Cu(II) ions removal from wastewater using starch nanoparticles (SNPs): An eco-sustainable approach

The complex structured starch particles were reduced to the nanoscale size range through hydrolysis utilizing low concentration acid assisted by ultrasound irradiation. The synthesized starch nanoparticles (SNPs) were characterized by transmission electron microscopy (TEM), Fourier-transform infrared (FTIR), and X-ray diffraction (XRD) techniques. The synthesized SNPs possessed surface activated entities, as many cationic functional groups were confirmed through the FTIR spectrum. Also, these SNPs were effectively utilized to separate heavy Cu metal ions from the synthetic ion solution. The SNPs were characterized using field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis for the surface modification after the adsorption process. The weak electrostatic interaction between the SNP surface and Cu ion was confirmed by the XPS spectrum and energy-dispersive X-ray spectroscopy. The maximum efficiency of Cu ions removal was about 93% at an optimal pH 5 and 25 mg/ml dosage. The adsorption equilibrium was obtained in 60 min. The nitrogen isotherm BET analysis of SNPs after adsorption shows a higher specific surface area of 18.552 m²/g, attributed to the interaction and presence of Cu ions on the SNP surface. The process feasibility was validated by the Langmuir isotherm model. The process exhibits pseudo-second-order adsorption kinetics and follows the Langmuir isotherm. The R_L predicted by the Langmuir isotherm mechanism is 0.017, implying favourable adsorption. The process is reproducible and allows for the separation of heavy metal ions from the wastewater through biosorption effectively.     

含铬废水的电化学法处理技术及研究进展

相比于六价铬,三价铬毒性更低且易形成不溶性沉淀物,将六价铬去除或还原为低毒的三价铬是废水除铬的关键过程。电化学技术因其通用性和环境相容性被广泛用于污水处理中,可通过"清洁试剂"——电子来实现Cr(Ⅵ)去除或分离。分别对电化学除铬技术如电絮凝、电化学还原/燃料电池、电渗析/电去离子/反向电渗析等技术的除铬机理及研究进展进行了回顾,并对电化学除铬技术的发展进行了总结和展望,作者认为电极材料的优化改性,集成反应器的开发与调控以及实现能源同步回收是今后电化学除铬技术的研究方向。     

Neural network modeling of Pb removal from wastewater using electrodialysis

Artificial neural network (ANN) was applied to predict separation percent (SP) of lead ions from wastewater using electrodialysis (ED). The aim was to predict SP of Pb²⁺ as a function of concentration, temperature, flow rate and voltage. Optimum numbers of hidden layers and nodes in each layer were determined. The selected structure (4:6:2:1) was used for prediction of SP of lead ions as well as current efficiency (CE) of ED cell for different inputs in the domain of training data. The modeling results showed that there is an excellent agreement between the experimental data and the predicted values.     

Adsorptive removal of alizarin dye from wastewater using maghemite nanoadsorbents

ABSTRACT

This is an investigation of the adsorptive removal of anthraquinone dyes, resembled by Alizarin, by utilizing maghemite iron oxide (γ-Fe₂O₃) nanoparticles in aqueous media. The adsorption process was affected by several parameters such as solution pH, adsorbent amount, contact time, and temperature. After optimizing the parameters affecting the adsorption, the process was successful in removing Alizarin dye with an efficiency exceeding 95%. Best adsorption results were achieved at a pH of 11 and contact time of 60 min. The adsorption was shown to follow the Langmuir model suggesting a monolayer and homogeneous coverage. The maximum adsorption capacity (q_m ) was found to be 23.2 mg/g at pH = 11. A thermodynamic study showed that the adsorption process is exothermic and spontaneous at room temperature. The Gibbs free energy of adsorption (-6.79 kJ/mol) obtained in this study suggests a physisorption process. This finding has facilitated the regeneration of the Fe₂O₃ nanocatalyst. Both NaOH and HNO₃ at dilute levels were tested for the regeneration of the nanocatalyst. Regeneration with HNO₃ was successful up to four successive removal cycles with an efficiency >80%. Photodegradation experiments utilizing a UV light were also successful in maximizing the adsorption removal efficiency. A sorption mechanism based on the results obtained in this work is also proposed.     

小麦谷朊粉及淀粉生产废水处理中超滤膜的选择

通过实验研究了不同截留相对分子质量和膜材料的超滤膜在超滤小麦谷朊粉及淀粉生产废水时的渗透通量、膜衰减系数、蛋白质截留率、还原糖透过率。根据实验结果综合分析表明:PS-10膜浓缩小麦淀粉废水时膜衰减系数为0.1841、蛋白质截留率为72.2%、还原糖透过率为86.2%,是超滤浓缩分离此废水的适宜用膜。     

脉冲电源电解处理含氰含银电镀废水

利用脉冲电源从含氰含银电镀废水中回收银和去除氰,对比了脉冲电源与直流电源对含氰镀银废水的处理效果,系统研究了脉冲电源的电解电压、占空比和脉冲频率等参数对电能消耗、银回收率和除氰率的影响。结果表明,脉冲电源较直流电源能更加有效降低阳极的超电位,减少电极的极化,从而降低槽电压,进而有效地降低电能消耗。脉冲电源的优化参数是：脉冲电压2.0 V,脉冲频率1200 Hz,占空比50%。在循环流速100 ml·min^-1,pH值10～11,曝气速率1.0 L·min^-1的实验条件下,通入电解电压2.0 V、脉冲频率1200 Hz以及占空比50%的脉冲电源,电解2.0 h后,银回收率高达99%,除氰率达到86%。     

Dye removal from colored textile wastewater using acrylic grafted nanomembrane

In this paper, the dye removal ability of the acrylic grafted polysulfone nanomembrane using ultraviolet radiation was studied to remove dyes from colored textile wastewater. Acrylic acid was used to modify polysulfone ultrafiltration membrane. The effect of different operating parameters such as pressure, salt concentration and chemical structure of dyes was evaluated. Data indicated that the photografted membrane has acceptable performance both in terms of flux and rejection. The dye rejection and hydraulic permeability were 86–99.9% and 7.6 L m^{− 2} h^{− 1} bar^{− 1}, respectively. It was found that the rejection of dyes decreased with salt concentration due to a decrease of the Donnan effect. Also, the low molecular weight dyes and highly charged dyes were more sensitive in the presence of salts. Addition of 80 mM Na₂SO₄ in dye solution decreased the dye rejection more than 15%. The rejection enhancement for all cases was negligible by increasing driving pressure from 1 to 4 bar. Dyes with low charger were more sensitive to operating pressure than that of dyes with higher charges. All findings supported that acrylic grafted nanomembrane is potentially capable to separate dyes from colored textile effluent.     

An overview of heavy metal removal from wastewater using magnetotactic bacteria

Considering the increase in water contamination by heavy metal discharge, water quality experts are focusing on innovative future technologies for wastewater treatment. There are a number of physical, chemical and biological processes for acquiring high‐quality effluents; however, these treatment technologies have shown some limitations regarding their specific pollutant removal efficiencies, vulnerability to environmental pollutants, higher cost and energy requirements, excessive sludge volume and toxicity issues. Therefore, this review/concept paper focuses on the application of magnetotactic bacteria (MTB) in the removal of heavy metal from wastewater and also proposes a model application of MTB‐based treatment process. The unique property of the MTB is to move along the periphery of the applied external magnetic fields due to nano sized magnetosomes (MS). MS are basically the biomineral crystals of either magnetite (Fe₃O₄) or greigite (Fe₃S₄) with a size range of 30–120 nm. Moreover, challenging aspects concerning MTB employment in the removal of heavy metal from wastewater also are discussed in detail for the consideration of experts who are involved in the development of new treatment technologies or for retrofications of existing processes. © 2018 Society of Chemical Industry