Enhanced Electrokinetic Remediation of Zinc Contaminated Soil by Changeover of Composite Electrolyte

The combination of electrolytes 0.1 M potassium chloride (KCl) and 0.1 M citric acid (CA) was investigated in a bench scale reactor for removal of zinc (Zn) from soil using electrokinetic remediation (EKR). The study was conducted over a period of 144 hours for different experimental set-ups. When KCl was used as a single electrolyte, 49.38 % removal of zinc was obtained with the changeover of electrolyte at every 24 hours, as compared to 12.5 %, when the reactor was operated as batch reactor without changeover. The use of composite electrolyte in cathode compartment and single electrolyte in anode compartment showed 79.06 % removal, whereas the use of composite electrolyte in both anode and cathode compartment gave 21.74 % removal.

Cathodic reduction characteristics of 2-chloro-4-nitrophenol in microbial electrolysis cell

Microbial electrolysis cell (MEC) has been constructed to study the degradation characters of 2-chloro-4-nitrophenol (2C4NP) in waste water. The effects of applied voltage, initial concentration of substrate and co-matrix species on the reduction and degradation of 2C4NP were studied. Qualitative and quantitative analysis of 2C4NP residues and degradation intermediate by using UV-Vis, HPLC, HPLC/MS/MS, IC and other analytical testing techniques. The degradation mechanism of 2C4NP in MEC cathode was proposed. The results showed that electron and electroactive microorganisms would produce coupling effect and accelerate the degradation of 2C4NP under adding 0.5 V DC; Under the condition of satisfying the C/N ratio of electroactive anaerobic microorganism, the addition of organic substances such as glucose and sodium acetate which were easily degraded by microorganisms would hinder the degradation of 2C4NP in the cathode compartment. 2C4NP can be effectively degraded by adding appropriate amount of glucose as carbon source with the low C/N. 2C4NP undergoes reduction, dechlorination, denitrification and assimilation in the cathode compartment to form 2-chloro-4-aminophenol, 4-aminophenol, 2-chlorophenol, 2-chloro-4-hydroxyphenol, nitrophenol, hydroquinone, 4-hydroxyhexadienoic acid semialdehyde, valeric acid, oxalic acid and many other intermediate products. According to the degradation intermediates, the degradation mechanism of 2C4NP in the cathode compartment was presumed.

Gas-permeable hydrophobic tubular membranes for ammonia recovery in bio-electrochemical systems

Integration of a gas-permeable hydrophobic membrane in the cathode compartment of a bio-electrochemical system enables efficient ammonia recovery from wastewater.

Characterization Parameters in the Heavy Metal Electrokinetic Removal Process of the Fly Ash

Electrokinetic removal is a new kind of technology and it is paid close attention in many countries. This work shows the laboratory results of electrodialytic removal experiments about the fly ash from municipal solid waste in Chongqing. The characterization parameters of the electrolyte solution pH, electric current, electrical conductivity, voltage gradient were discussed after the experiment. The pH value changed smoothly in the cathode compartment, while it changed abruptly in the first 6 hours, but it changed smoothly in the rest time in the anode compartment. The electrical current increased in the first 50 hours, then gradually decreased in the rest time. The higher the electrical current is, the better the removal effect is. The electrical conductivity in the anode compartment increased while the electrical conductivity decreased in the cathode compartment. The higher the electrical conductivity is, the better the removal effect is. The metal hydroxide precipitation was the most serious factor that influenced the removal rate.