Effect of electrode configuration and voltage variations on electrocoagulation process in phosphate removal of laundry wastewater

Indonesia is one of the countries that still have to deal with waste problems. In reducing waste, the government has made a series of efforts to reduce waste, especially wastewater. There are many kinds of wastewater. One of them is laundry wastewater. This research aims to estimate the dangerous substance in laundry wastewater and how to treat it. The method using some variables like Al-Al, Al-Fe, Fe-Fe, and Fe-Al and the voltage is changing from 20 V, 30 V, 40 V, and 60 V. The research shows that the most optimum result of laundry wastewater treatment was using Al-Fe electrode plate 60 V. The result that the phosphate concentration decreased by 6.56 mg/l from 9.58 mg/l to 3.01 mg/l and obtained phosphate removal efficiency of 68.56%. The most optimum results for the removal of phosphate levels contained in the 60 V voltage.

Research on performance optimization and mechanism of electrochemical water softening applied by pulse power supply

In order to promote the application of electrochemical water softening technology in industrial circulating cooling water systems, electric field type, cathode structure and solution residence time are selected for optimization analysis of electrochemical water softening device. The experimental results show that the water softening performance per unit area of mesh cathode is better than that of plate cathode. In addition, the softening amount per unit area of the mesh cathode can be further increased when the high-frequency (HF) power supply is applied. When the HF power supply is applied, the softening amount per unit area is 158.58 g/m2·h−1 more than that the direct current power supply is applied. In order to explore the growth mechanism of calcium carbonate, micro-analysis technology and high-speed bubble photography technology are used. The results show that the bubbles escape along the longitudinal direction of the electrode plate, and the main growth direction of calcium carbonate growth is consistent with the escape direction of the bubble, that is, the bubbles grow along the longitudinal direction of the electrode plate. The special structure of the diamond-shaped mesh cathode facilitates the growth of calcium carbonate crystals.

Design of Driving Waveform for Shortening Red Particles Response Time in Three-Color Electrophoretic Displays

Three-color electrophoretic displays (EPDs) have the advantages of multi-color display and low power consumption. However, their red particles have the disadvantage of long response time. In this paper, a driving waveform, which is based on electrophoresis theory and reference gray scale optimization, was proposed to shorten the response time of red particles in three-color EPDs. The driving waveform was composed of erasing stage, reference gray scale forming stage, red driving stage, and white or black driving stage. Firstly, the characteristics of particle motion were analyzed by electrophoresis theory and Stokes law. Secondly, the reference gray scale of the driving waveform was optimized to shorten the distance between red particles and a common electrode plate. Finally, an experimental platform was developed to test the performance of the driving waveform. Experimental results showed that the proposed driving waveform can shorten the response time of red particles by 65.57% and reduce the number of flickers by 66.67% compared with the traditional driving waveform.

Optimization for simultaneous removal of NH3-N and COD from coking wastewater via a three-dimensional electrode system with coal-based electrode materials by RSM method

The present work demonstrated preparation of coal-based electrode materials (CEM)-derived low-rank coal for simultaneous removal of ammonia nitrogen (NH3-N) and chemical oxygen demand (COD) from coking wastewater by a three-dimensional electrode system (3DES). The influence of important parameters in 3DES such as processing time, applied voltage, electrode plate spacing, mass of commercially activated carbon (CAC), and initial pH were investigated. Based on the central composite design, the response surface method (RSM) was employed in order to optimize the variable parameters in removal process of pollutants. From the analysis of RSM, the optimum conditions for 3DES were 4.5 h of processing time, 5.5 V of applied voltage, 17 mm electrode plate spacing, 4.5 g CAC, and pH of 3 with higher simultaneous removal rate of COD (74.20%) and NH3-N (51.48%). Besides, the content of N element (4.9%) and N containing groups were traced by SEM-EDS and FTIR analysis in order to verify the removal effect. The experiment results showed the capability of CEM for electrode system removal of pollutants from coking wastewater and obtained considerable simultaneous removal rate of NH3-N and COD.

Revamp of existing lab-scale electrolytic cell design for electrolyzed water study in cleaning application

The lab-scale electrolytic cell was designed to produce acidic and alkaline electrolyzed water for cleaning study. Electrolyzed water (EW) was produced by electrolysis of a dilute sodium chloride solution. The generation of free chlorine, pH and oxidation-reduction potential from the electrolysis process by the electrolytic cell were far from the expected value. Thus, the lab-scale electrolytic cell was revamped by using the acrylic slot to hold the electrode plate and a membrane holder without metal screws. This revamp work is to reduce the resistance for current flow with the aim to increase the value of chemical properties (pH, oxidation-reduction potential, free chlorine) for acidic and alkaline electrolyzed water. Findings have shown that the current was increased from 0.013A to 2.5A after the revamp process. As a result of the revamp, the value of pH, oxidationreduction potential and free chlorine for acidic electrolyzed water was increased by 1.7 times, 2.7 times, and 20 times higher than previous results respectively. While for alkaline electrolyzed water, the value of pH and oxidation-reduction potential was increased by 1.4 times and 6.2 times higher than previous results respectively.