Removal of arsenic from drinking water by the electrocoagulation using Fe and Al electrodes

A novel technique of electrocoagulation (EC) was attempted in the present investigation to remove arsenic from drinking waters. Experiments were carried out in a batch electrochemical reactor using Al and Fe electrodes with monopolar parallel electrode connection mode to assess their efficiency. The effects of several operating parameters on arsenic removal such as pH (4–9), current density (2.5–7.5 A m⁻²), initial concentration (75–500 μg L⁻¹) and operating time (0–15 min) were examined. Optimum operating conditions were determined as an operating time of 12.5 min and pH 6.5 for Fe electrode (93.5%) and 15 min and pH 7 for Al electrode (95.7%) at 2.5 A m⁻², respectively. Arsenic removal obtained was highest with Al electrodes. Operating costs at the optimum conditions were calculated as 0.020 € m⁻³ for Fe and 0.017 € m⁻³ for Al electrodes. EC was able to bring down aqueous phase arsenic concentration to less than 10 μg L⁻¹ with Fe and Al electrodes. The adsorption of arsenic over electrochemically produced hydroxides and metal oxide complexes was found to follow pseudo second-order adsorption model. Scanning electron microscopy was also used to analyze surface topography of the solid particles at Fe/Al electrodes during the EC process.     

Investigation of shipyard wastewater treatment using electrocoagulation process with Al electrodes

In this study, shipyard oily wastewater treatment was investigated by electrocoagulation (EC) using aluminum electrodes in a batch reactor by evaluating different operation conditions. The maximum chemical oxygen demand (COD) removal efficiency of 88.83% was obtained at current density of 3 mA/cm². The removal efficiency was gradually improved with increasing current density and decreased with increasing COD concentration. However, initial pH value was not determinant factor for this process. Total energy and electrode cost were calculated as $0.88 per m³ treated wastewater. The result of this research shows that EC process seems to be an efficient method for the oily wastewater treatment.     

Treatment of potato chips manufacturing wastewater by electrocoagulation

Treatment of wastewater from potato chips manufacturing by electrocoagulation (EC) was investigated. Experiments were conducted to determine the optimum operating conditions such as electrode type, pH, current density and retention time. Aluminium and iron electrodes were used, and aluminium electrodes were found to be more suitable since it had a higher removal rate of COD, turbidity and suspended solids than the iron electrode. The removal efficiencies of COD and turbidity were high, being 60% and 98%, respectively, with retention time < 40 min. 0.05–1.75 kg (per kg COD removed) of dried sludge was removed. COD removal kinetics during EC process was described by a macro-kinetics model. Results from the kinetic studies showed that the kinetic data fit the second-order kinetic model well. The operating costs investigated in the present study were the energy cost of EC and the material cost due to the consumption of aluminium electrode. Operating costs were varied in the range of 0.48 to 5.42 $/m³ and 0.62 to 6.32 $/m³ wastewater treated at 20–300 A/m² and 5–40 min, respectively. The energy consumption was 4 kWh/m³ for wastewater treated less than 8 min under typical operating conditions.     

Heavy metal ions removal from wastewater using electrocoagulation processes: A comprehensive review

A vast number of publications have investigated the application of electrocoagulation (EC) process in heavy metal ions removal from wastewaters. Most of these studies were simple lab-scale using synthetic wastewater with the absence of holistic and systematic approach to consider the process complexity. This comprehensive review considers the fundamental aspects of EC processes such as mechanisms, kinetic models, and isotherm models used by different researchers. Furthermore, the impact of the main design and process operational parameters on the removal efficiency is discussed and analyzed. Many concluding remarks and perspectives are stated to give insights for possible future investigations.     

An empirical model for kinetics of boron removal from boroncontaining wastewaters by the electrocoagulation method in a batch reactor

Boron removal from boron containing wastewaters prepared synthetically via the electrocoagulation method was studied. The experiments in which aluminum plate electrode was used were carried out in a batch reactor. The solution pH, initial boron concentration, current density, type of supporting electrolyte, temperature of solution and stirring speed were selected as experimental parameters. The obtained experimental results showed that efficiency of boron removal increased with increasing current density and decreased with increasing boron concentration in the solution. Supporting electrolyte had not significant effects on the percent of total boron removal. pH was very important parameter effecting boron removal and optimum pH was determined to be 8.0. This pH value reached an agreement with activity-pH diagrams for Al⁺³ species in equilibrium with Al(OH)₃ and boron species in aqueous media. As a result of increasing interaction between boron ions and dissolved aluminum ions in solution, the increasing solution temperature increased boron removal efficiency. Increasing stirring speed decreased boron removal efficiency where the increasing stirring speed decreased the capability of floc formation of aluminum ions. As a result, it was seen that about 99% of boron in the wastewater could be removed at optimum conditions. In addition, the process kinetics was predicted by using heterogeneous fluid–solid reaction models. It was seen statistically that the kinetics of this process agreed with the pseudo-second-order model as follows: X_B/(l−X_B) = 18,241[OH][C]^−3.45[CD]^7.79[t]^1.41[S]^−3.65exp[−30,668/RT].     

Evaluation of boron removal by electrocoagulation using iron and aluminum electrodes

Boron compounds are used in the variety of products manufacturing and are introduced to the environment in the form of waste. Here the feasibility of the boron removal from wastewater by electrocoagulation (EC) is studied. Aluminum and iron were simultaneously used in the reactor as materials for cathode and anode. The results show that the EC process for boron removal strongly depends on the current density, initial concentrations, and time. The process is examined under varying indices in order to determine optimal operating conditions. It is important to note the EC application needs no chemical reagents and makes the boron-containing wastewater treatment easy for regulation and automation.     

金属切削液在线循环净化系统设计及研究

针对金属切削液失效变质和腐败变质的根源,设计了多级磁分离技术与臭氧-气浮技术联用的处理工艺,并对金属切削液进行了净化再生试验。在切削液进水流量为300 L/h,臭氧加入量为进水体积的10%,共聚气浮分离系统压力为0.15 MPa时,经该系统处理40 min,即可有效去除导致切削液失效的油污、悬浮物、微生物。     

Investigation on the electrolysis voltage of electrocoagulation

The relation between electrolysis voltage and the other variables of an electrocoagulation process was analyzed. Theoretical models describing such a relation were established. Experiments were conducted to confirm the theoretical analysis and to determine the constants in the models. Both the theoretical analysis and experiments demonstrated that water pH and flow rate had little effects on the electrolysis voltage within a large range. The electrolysis voltage depends primarily on the inter-electrode distance, conductivity, current density and the electrode surface state. The models obtained can be used to calculate the total required electrolysis voltage for an electrocoagulation process.     

电絮凝法处理含油废水的研究

通过石墨-石墨、铝-石墨、铅-石墨、铁-石墨和铝-铁等5种电极组合分别处理含32#机油的废水。研究发现，铝-石墨为最佳电极组合，通过正交实验设计，选择固体悬浮物(SS)、化学需氧量(COD)和含油量的去除率较大的条件是：电解质(NaCl)为3g，电解电压为10V，电解时间为25min。     

Treatment of the textile wastewaters by electrocoagulation: Effect of operating parameters on the sludge settling characteristics

This paper deals with treatment of industrial wastewaters by electrocoagulation technique, with emphasis on settling process. The influence of electrode material, current density, pH, treatment period on the sludge settling characteristics has been investigated. The wastewater issued from textile industry is characterized by its high suspended solids content (SS₀), its high turbidity (NTU) and a fair chemical oxygen demand (COD). The wastewater treatment process consisted in a preliminary electrocoagulation step, followed by a settling step conducted without addition of flocculating agents. Sludge settling velocity after electrocoagulation was measured depending on the operating conditions. The data were employed to investigate the influence of the process parameters on the settling process. The sludge settling data were utilized to compare the efficiency of various empirical models for estimation of sludge settling velocity. Finally, the sludge aptitude to settling was studied in terms of sludge volume index (SVI) to determine the best operating conditions.     

粉煤灰处理含重金属废水试验研究

本文比较了粉煤灰及酸活化粉煤灰处理重金属离子的性能 ,着重探讨了酸活化粉煤灰去除工业电镀废水中重金属离子铬、铅、铜、镉的适宜条件 ,经处理后的废水可达到排放标准。同时提出了一套成功的粉煤灰活化工艺 ,具有较好的社会效益和经济效益。     

从钴镍切削废料中回收有价金属的方法

研究了以钴、镍合金切削废料为原料，通过酸溶、除铁、除铬、钴镍分离等过程，回收有价金属氧化钴、氢氧化镍的工艺条件，通过生产实践，确定了最佳工艺条件及生产工艺，得到的产品质量分别达到国家标准和企业标准。     

臭氧氧化法处理焦化废水的研究

本文研究了臭氧对焦化废水的处理,提出了臭氧氧化酚的机理。研究发现,对于COD值小于1000mg/L、酚含量小于500mg/L的焦化废水,臭氧氧化是很有效的。     

Reversible adsorption of metalworking fluids (MWFs) on Cu-BTC metal organic framework

Metalworking fluids(MWFs) are classified as hazardous substances. Due to the characteristics of the stable oil–water emulsions, it requires more costly and complicate treatment techniques to remove oil from spent MWFs. Metal organic frameworks(MOFs) are a porous network material used to remove contaminants from environment. One of the most prominent of MOFs is HKUST-1 or Cu-BTC. In this study, the Cu-BTCs were prepared by solvothermal method in various conditions and used as absorbent for removing oil micelles in MWF emulsion. The particle size of all synthesized Cu-BTCs ranged from ≈80 to 400 nm. The ability of all synthesized Cu-BTCs to remove oil micelle was greater than 95% in 60 min, while the capacity of GAC was obtained the result for only 6.8%. The maximum adsorption capacity(q _(max)) of oil micelles on Cu-BTCs was 1666.7 mg·g~(-1). The highest removal capacity of oil micelles in MWF emulsion is greater than 99% in 24 h by using Cu-BTCs washed with either butanol or ethanol.     

Dependency of removal efficiency on electrode arrangements in the treatment of oily wastewaters by electrocoagulation

Turbidity and chemical oxygen demand (COD) removal efficiencies were analyzed depending on electrode layouts by performing electrocoagulation experiments using horizontal and vertical electrochemical cells. Multiple aluminum plate electrodes were placed into different sections of the electrochemical cells. Removal efficiencies at the horizontal electrochemical cell were always higher than the one’s obtained from the vertical electrochemical cell. But the use of vertical electrochemical cell consumed less energy during the electrocoagulation tests. The highest COD removal efficiencies were 97% and 88% in the horizontal and vertical electrochemical cells, respectively. However, the energy consumption for COD removal in the horizontal electrochemical cell was 47% higher than the energy consumed in the vertical electrochemical cell.     

湿热法在废油脂处理中的应用

研究湿热法在废油脂处理中的应用,考察了温度、压力、时间和水用量等处理因素对实验结果的影响,确定了最佳处理条件,即：废油脂30g、水12g于100℃密闭湿热处理45min,所得油脂的品质明显改善,酸值由2．26mgKOH／g降为2．06nagKOH／g,碘值由73．84g／100g降为70．80g／100g,皂化值由200．27nagKOH／g升至204．39nagKOH／g。上述结果表明,经湿热法处理后的油脂更适合于生物柴油的制备。     

Applied of central composite design for the optimization of removal yield of the ketoprofen (KTP) using electrocoagulation process

ABSTRACT

In this paper, the modeling and the optimization of the removal efficiency of ketoprofen (KTP) by the electrocoagulation process were studied. The central composite design experiments (CCD) method was used to study the main effects and the interaction effects between operational parameters and to optimize the value of each parameter. According to the regression equation obtained, the current density appears to be one of the most important parameters (b₂ = +22.11) controlling the removal efficiency of KTP. The positive sign of b₂ coefficient suggests that the increase of current density increases the yield of removal. The second signi?cant parameter with a negative effect was the initial KTP concentration (b₃ = ?16.27). This result suggests that the removal efficiency was inversely proportional to the initial concentration. In addition, according to the model, the most influencing interactions were pH-current density, pH-initial concentration, and current density-initial concentration. The model obtained by CCD led to the following optimal conditions for KTP removal e?ciency (96.70%): pH = 7, i = 24.04 mA cm^?2, and C₀ = 5 mg L^?1.     

废弃混凝土中基质胶凝组分作水泥混合材料的研究

采用热处理和加入表面活性剂的方法将废弃混凝土中的骨料与基质胶凝组分进行分离。将分离出的基质胶凝组分（FWC）按照不同配合比掺入水泥熟料中粉磨不同时间测试其性能。结果表明：FWC的易磨性优于水泥熟料，FWC具有较强的水化能力和较好的胶凝性，可以作为一种水泥混合材料。     

吸附法处理重金属废水的研究进展

综述了吸附法处理重金属废水的研究进展。讨论了天然材料、合成材料、改性材料、生物材料等种类的吸附剂,探讨了各类吸附剂的吸附机理和影响吸附的因素。展望了未来水处理吸附剂的发展方向,廉价的、高效的、无二次污染的吸附剂将会得到大力开发。     

重金属离子捕集沉淀剂DTCR处理含镉废水工艺研究

用改进的单叶直式搅拌器,采用分段搅拌法,以重金属离子沉淀剂DTCR处理含镉废水,着重考察了搅拌强度、时间对除镉的影响,生成的沉淀在不同pH条件下进行了溶出实验。结果表明,对1 L含镉废水,260 r/min加入0.3%DTCR 4.4 mL,搅拌1.5 min;120 r/min加入0.1%PAM0.8 mL,搅拌1 min;40 r/min搅拌8 min,镉除去率>99%,反应时间10.5 min,沉降15 min。其工艺特点:DTCR直接投放,不调整废水pH,镉及共存金属离子同时处理,工艺简便,条件温和,清液达标。溶出实验显示,沉淀的化学性质稳定,不造成二次污染。