scholarly journals Electrocoagulation for spent coolant from machinery industry

2017 ◽  
Vol 8 (4) ◽  
pp. 497-506 ◽  
Author(s):  
W. Pantorlawn ◽  
T. Threrujirapapong ◽  
W. Khanitchaidecha ◽  
D. Channei ◽  
A. Nakaruk
Keyword(s):  
Energy Consumption ◽  
Current Density ◽  
Specific Energy ◽  
Specific Energy Consumption ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Industrial Wastes ◽  
Electrolysis Time ◽  
Current Densities ◽  
Sludge Production

Abstract Spent coolant is considered as one of the most polluting industrial wastes and causes environmental problems. It mostly contains high non-biodegradable organic carbon and oil contents; the biodegradability index was very low at 0.04, which is difficult to be effectively treated by common treatment systems. Electrocoagulation (EC) was proposed for a pre-treatment of coolant. The laboratory-scale of EC reactor was developed with Al electrodes and 10 mm of interelectrodes. The efficiency of the EC reactor on chemical oxygen demand (COD) removal was investigated at various current densities and electrolysis times. The highest current density of 50 mA/cm2 induced a short electrolysis time of 10 min to reach the steady state of approximately 65% COD removal. When lower current densities of 20–40 mA/cm2 were supplied to the EC reactor, COD removal efficiency of 65% can be achieved at longer electrolysis times. According to the specific energy consumption and sludge production, the optimal condition for spent coolant treatment was the current density of 20 mA/cm2 and electrolysis time of 30 min in which a COD removal of efficiency of 68% was obtained, 0.88 kWh/kg-COD of the specific energy consumption and 0.04 kg/kg-COD of the sludge production.

scholarly journals The Optimum Electrolyte Parameters in the Application of High Current Density Silver Electrorefining

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1596
Author(s):  
Arif T. Aji ◽  
Jari Aromaa ◽  
Mari Lundström
Keyword(s):  
Energy Consumption ◽  
Current Density ◽  
Specific Energy ◽  
Composition Range ◽  
High Current Density ◽  
Specific Energy Consumption ◽  
Production Capacity ◽  
Cell Voltage ◽  
Process Efficiency ◽  
High Current

Increasing silver production rate has been a challenge for the existing refining facilities. The application of high current density (HCD) as one of the possible solutions to increase the process throughput is also expected to reduce both energy consumption and process inventory. From the recently-developed models of silver electrorefining, this study simulated the optimum electrolyte parameters to optimize the specific energy consumption (SEC) and the silver inventory in the electrolyte for an HCD application. It was found that by using [Cu2+] in electrolyte, both objectives can be achieved. The suggested optimum composition range from this study was [Ag+] 100–150 g/dm3, [HNO3] 5 g/dm3, and [Cu2+] 50–75 g/dm3. HCD application (1000 A/m2) in these electrolyte conditions result in cell voltage of 2.7–3.2 V and SEC of 0.60–1.01 kWh/kg, with silver inventory in electrolyte of 26–39 kg silver for 100 kg per day basis. The corresponding figures for the conventional process were 1.5–2.8 V, 0.44–0.76 kWh/kg, and 15.54–194.25 kg, in respective order. These results show that, while HCD increases SEC by app. 30%, the improvement provides a significant smaller footprint as a result of a more compact of process. Thus, applying HCD in silver electrorefining offers the best solution in increasing production capacity and process efficiency.

scholarly journals Organic Pollutants Removal from Olive Mill Wastewater Using Electrocoagulation Process via Central Composite Design (CCD)

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3522
Author(s):  
Abeer El Shahawy ◽  
Inas A. Ahmed ◽  
Mahmoud Nasr ◽  
Ahmed H. Ragab ◽  
Saedah R. Al-Mhyawi ◽  
...  
Keyword(s):  
Weight Loss ◽  
Current Density ◽  
Operating Cost ◽  
Oxygen Demand ◽  
Olive Mill Wastewater ◽  
Cod Removal ◽  
Electrolysis Time ◽  
Faraday’S Law ◽  
Central Composite ◽  
Olive Mill

Electrocoagulation (EC) was studied in this study as a potential alternative approach for treating Olive Mill Wastewater (OMW). Aluminum plates were utilized as anode and cathode to evaluate the removal of Chemical Oxygen Demand (COD) from OMW and the aluminum electrode’s weight loss. Central Composite Experimental Design (CCD) and Response Surface Methodology were used to optimize its performance. Anodes were weighed before and after each electrocoagulation experiment, to compare the experimental and the theoretical dissolved aluminum weights calculated using Faraday’s law. We discovered the following EC conditions for CCD: current density = 15 mA/cm2, pH = 4, and electrolysis time of 30 min. Under these conditions, the maximum COD removal ratio was 41%, equating to an Al weight loss of 288.89 g/m3 at an estimated operating cost of 1.60 USD/m3. According to the response optimizer, the most economical operating settings for COD removal efficiency of 58.888% are pH 4, a current density of 18.41 mA/cm2, electrolysis time of 36.82 min, and Al weight loss of 337.33 g/m3, with a projected running cost of 2.00 USD/m3.

scholarly journals Fluoride Removal from Industrial Effluents by Combining Precipitation and Electrocoagulation Processes

2019 ◽  
Vol 70 (1) ◽  
pp. 304-306 ◽  
Author(s):  
Monica Ihos ◽  
Mihaela Dragalina ◽  
Iuliana Iordache ◽  
Dorian Neidoni
Keyword(s):  
Energy Consumption ◽  
Industrial Wastewater ◽  
Supporting Electrolyte ◽  
Specific Energy Consumption ◽  
Industrial Effluents ◽  
Fluoride Removal ◽  
Sacrificial Anode ◽  
Electrolysis Time ◽  
Applied Current ◽  
Current Densities

The aim of this study was the removal of fluoride from a fluoride-rich industrial wastewater by combining two processes, precipitation with a magnesium salt and electrocoagulation. The sacrificial anode was made of Al and the applied current densities were of 100, 200 and 300 A/m2, respectively. The experiments were conducted at pH of 5.2, 6.2 and 7.2, respectively, and the electrolysis time was of 15, 30, 45 and 60 min, respectively. 0.01 M NaCl was supporting electrolyte. The best results were obtained at pH of 6.2, 200 A/m2 and 45 minutes of electrolysis when the specific energy consumption was of 5.6 kWh/m3.

scholarly journals Energy consumption of agitators in activated sludge tanks – actual state and optimization potential

2017 ◽  
Vol 77 (3) ◽  
pp. 800-808 ◽  
Author(s):  
K. Füreder ◽  
K. Svardal ◽  
W. Frey ◽  
H. Kroiss ◽  
J. Krampe
Keyword(s):  
Energy Consumption ◽  
Power Density ◽  
Specific Energy ◽  
Operating Time ◽  
Specific Energy Consumption ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Actual State ◽  
Total Energy Consumption ◽  
Continuous Mixing

Abstract Depending on design capacity, agitators consume about 5 to 20% of the total energy consumption of a wastewater treatment plant. Based on inhabitant-specific energy consumption (kWh PE120−1 a−1; PE120 is population equivalent, assuming 120 g chemical oxygen demand per PE per day), power density (W m−3) and volume-specific energy consumption (Wh m−3 d−1) as evaluation indicators, this paper provides a sound contribution to understanding energy consumption and energy optimization potentials of agitators. Basically, there are two ways to optimize agitator operation: the reduction of the power density and the reduction of the daily operating time. Energy saving options range from continuous mixing with low power densities of 1 W m−3 to mixing by means of short, intense energy pulses (impulse aeration, impulse stirring). However, the following correlation applies: the shorter the duration of energy input, the higher the power density on the respective volume-specific energy consumption isoline. Under favourable conditions with respect to tank volume, tank geometry, aeration and agitator position, mixing energy can be reduced to 24 Wh m−3 d−1 and below. Additionally, it could be verified that power density of agitators stands in inverse relation to tank volume.

scholarly journals Electrooxidation Using Nb/BDD as Post-Treatment of a Reverse Osmosis Concentrate in the Petrochemical Industry

2019 ◽  
Vol 16 (5) ◽  
pp. 816 ◽  
Author(s):  
Salatiel Wohlmuth da Silva ◽  
Carla Venzke ◽  
Júlia Bitencourt Welter ◽  
Daniela Schneider ◽  
Jane Zoppas Ferreira ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Reverse Osmosis ◽  
Specific Energy ◽  
Energy Requirement ◽  
Specific Energy Consumption ◽  
Oxygen Demand ◽  
Inorganic Ions ◽  
Oxidation Time ◽  
Kinetic Regime ◽  
Boron Doped Diamond

This work evaluated the performance of an electrochemical oxidation process (EOP), using boron-doped diamond on niobium substrate (Nb/BDD), for the treatment of a reverse osmosis concentrate (ROC) produced from a petrochemical wastewater. The effects of applied current density (5, 10, or 20 mA·cm−2) and oxidation time (0 to 5 h) were evaluated following changes in chemical oxygen demand (COD) and total organic carbon (TOC). Current efficiency and specific energy consumption were also evaluated. Besides, the organic byproducts generated by EOP were analyzed by gas chromatography coupled to mass spectrometry (GC–MS). The results show that current densities and oxidation time lead to a COD and TOC reduction. For the 20 mA·cm−2, changes in the kinetic regime were found at 3 h and associated to the oxidation of inorganic ions by chlorinated species. After 3 h, the oxidants act in the organic oxidation, leading to a TOC removal of 71%. Although, due to the evolution of parallel reactions (O2, H2O2, and O3), the specific energy consumption also increased, the resulting consumption value of 66.5 kW·h·kg−1 of COD is considered a low energy requirement representing lower treatment costs. These results encourage the applicability of EOP equipped with Nb/BDD as a treatment process for the ROC.

scholarly journals Anodic oxidation of synthetic refinery effluent on lead anode: mass transport and charge rate balance

2021 ◽  
Author(s):  
T. Zier ◽  
S. Bouafia-Chergui ◽  
M. Chabani
Keyword(s):  
Energy Consumption ◽  
Mass Transport ◽  
Anodic Oxidation ◽  
Current Density ◽  
Supporting Electrolyte ◽  
Electric Energy ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Synthetic Wastewater ◽  
Charge Rate

Abstract A synthetic wastewater based on Algiers refinery real effluent was prepared and treated using anodic oxidation. Full factorial plan design was used to conduct the statistical analysis of the results. The aim of the study was to assess the interaction between current density (CD) and stirring degree (SD), and quantify their effects on chemical oxygen demand (COD) removal and electric energy specific consumption (EESC). With an initial COD of 487 mg/l, pH of 5.5 and 0.05 M of Na2SO4 as supporting electrolyte, it was found that a 55 rpm steering degree variation lead to a substantial gain in COD removal and energy consumption, 6% and 8.5 KWh/kg, respectively. Current density was found to have different effect on removal efficiency within the applied stirring domain, and that mass transport coefficient (km) is inversely correlated to energy consumption. Theoretical model describing the process was reviewed and the relation between concentration, hydrodynamics and applied current was emphasized.

scholarly journals Aluminium Recycling in Single- and Multiple-Capillary Laboratory Electrolysis Cells

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1053
Author(s):  
Andrey Yasinskiy ◽  
Sai Krishna Padamata ◽  
Ilya Moiseenko ◽  
Srecko Stopic ◽  
Dominic Feldhaus ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Mass Transport ◽  
Thin Layer ◽  
Current Density ◽  
Specific Energy ◽  
Transport Coefficient ◽  
Specific Energy Consumption ◽  
Electrolysis Cell ◽  
Aluminium Recycling ◽  
Mass Transport Coefficient

This work is a contribution to the approach for Al purification and extraction from scrap using the thin-layer multiple-capillary molten salt electrochemical system. The single- and multiple-capillary cells were designed and used to study the kinetics of aluminium reduction in LiF–AlF3 and equimolar NaCl–KCl with 10 wt.% AlF3 addition at 720–850 °C. The cathodic process on the vertical liquid aluminium electrode in NaCl–KCl (+10 wt.% AlF3) in the 2.5 mm length capillary had mixed kinetics with signs of both diffusion and chemical reaction control. The apparent mass transport coefficient changed from 5.6∙10−3 cm.s−1 to 13.1∙10−3 cm.s−1 in the mentioned temperature range. The dependence between the mass transport coefficient and temperature follows an Arrhenius-type behaviour with an activation energy equal to 60.5 J.mol−1. In the multiple-capillary laboratory electrolysis cell, galvanostatic electrolysis in a 64LiF–36AlF3 melt showed that the electrochemical refinery can be performed at a current density of 1 A.cm−2 or higher with a total voltage drop of around 2.0 V and specific energy consumption of about 6–7 kW.kg−1. The resistance fluctuated between 0.9 and 1.4 Ω during the electrolysis depending on the current density. Thin-layer aluminium recycling and refinery seems to be a promising approach capable of producing high-purity aluminium with low specific energy consumption.

Fouling of reverse osmosis and nanofiltration membranes by diary industry effluents

2002 ◽  
Vol 45 (12) ◽  
pp. 355-360 ◽  
Author(s):  
M. Turan ◽  
A. Ates ◽  
B. Inanc
Keyword(s):  
Energy Consumption ◽  
Reverse Osmosis ◽  
Specific Energy ◽  
Biological Treatment ◽  
Specific Energy Consumption ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Total Hardness ◽  
Feed Tank ◽  
Layer Resistance

Fouling experiments of nanofiltration (NF) and reverse osmosis (RO) are reported for treatment of the effluent of chemical-biological treatment plant and the original effluent of dairy industry respectively. In the experiments, a thin film composite type of spiral wound was used and fitted with flowmeters and pressure sensors. The feed water was stored into a feed tank and passed a fine filter and was pumped to membrane. Brine and permeate were recirculated back to the feed tank. Membrane fouling was investigated with 16 and 30% water recovery of a single membrane at different pressures and flowrates for RO and NF membranes respectively. Fouling is evaluated with a relationship between relative flux (J/Jo) which is the ratio of the flux at any time during the fouling test to the initial flux and relative resistance (Rf/Rm) which is the ratio of fouling (cake) layer resistance to clean membrane resistance. Turbidity, conductivity, chemical oxygen demand (COD), total suspended solids (TSS) and total hardness were measured in the feed and permeate side of each membrane. The effluent total hardness concentrations of chemical-biological treatment plant were found greater than the influents. The results are presented in terms of the relative flux as a function of time related to hydrodynamic conditions and pollution characteristics of wastewater. The permeate water flux of RO membrane decreases more rapidly than NF membrane. the relative flux decreases with increasing the fouling layer resistance, Rf onto membrane surface. 50% the drop of permeate flux was observed for RO and NF membranes after 50 h and 80 h of operation, respectively. The fouling rate increases with an increase in the concentration of the wastewater constituents in the dairy industry. The relative flux decreased 10 and 20% with increasing chemical oxygen demand (COD) from 5,000 mgl−1 to 10,000 mgl−1 and from 45 mgl−1 to 450 mgl−1 for RO and NF membranes, respectively after 45 h of time. Fouling of membranes resulted in 100% increase of specific energy consumption as the relative permeate fluxes of NF and RO membranes decreased 30 and 40% respectively. The average of specific energy consumption was obtained at 6 and 10 kWhm−3; consequently, operational costs were estimated at U.S. $0.45 m−3 and U.S. $0.75 m−3 for NF and RO units respectively. Also, operational cost for chemical-biological treatment was found at U.S. $0.30 m−3.

Recovery of Heavy Metal from Scrap Metal Pickling Wastewater by Electrolysis

1993 ◽  
Vol 28 (7) ◽  
pp. 223-229 ◽  
Author(s):  
Ju-Sheng Huang ◽  
I-Chung Lee ◽  
Biing-Jauh Lin
Keyword(s):  
Energy Consumption ◽  
Current Efficiency ◽  
Deposition Rate ◽  
Current Density ◽  
Specific Energy ◽  
Specific Energy Consumption ◽  
Copper Ion ◽  
Surface Loading ◽  
Electro Deposition ◽  
Continuous Flow Reactors

When the influent surface loading of copper ion in the four-stage continuous-flow reactors of electrolysis were controlled at 143.9, 94.0, 52.7 and 33.2 mg/min-dm2, respectively, and current density were controlled at 3.9, 2.6, 1.3 and 1.3A/dm2, respectively, the concentration of copper decreased from 13,900 to l,900mg/l (i.e., the electro-deposition rate of copper were 2,700, 2,240, 1,500 and 750 mg/dm2-h, respectively). The purity of copper depositing on the cathode reached over 98%. When the current density was ranged from 1.3 to 3.9A/dm2, the electro-deposition rate of copper increased with the increasing current density. However, when the current density was raised above 5.2 A/dm2, the electro-deposition rate of copper decreased with the increasing current density. The increase of current density decreased the current efficiency and increased the specific energy consumption. The increase of influent surface loading of copper ion increased the current efficiency and decreased the specific energy consumption.

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