Non-Thermal Plasma Sources Based on Cometary and Point-to-Ring Discharges

A non-thermal plasma (NTP) is a promising tool against the development of bacterial, viral, and fungal diseases. The recently revealed development of microbial resistance to traditional drugs has increased interest in the use of NTPs. We have studied and compared the physical and microbicidal properties of two types of NTP sources based on a cometary discharge in the point-to-point electrode configuration and a corona discharge in the point-to-ring electrode configuration. The electrical and emission properties of both discharges are reported. The microbicidal effect of NTP sources was tested on three strains of the bacterium Staphylococcus aureus (including the methicillin-resistant strain), the bacterium Pseudomonas aeruginosa, the yeast Candida albicans, and the micromycete Trichophyton interdigitale. In general, the cometary discharge is a less stable source of NTP and mostly forms smaller but more rapidly emerging inhibition zones on agar plates. Due to the point-to-ring electrode configuration, the second type of discharge has higher stability and provides larger affected but often not completely inhibited zones. However, after 60 min of exposure, the NTP sources based on the cometary and point-to-ring discharges showed a similar microbicidal effect for bacteria and an individual effect for microscopic fungi.

Reduced breakdown voltage for in-liquid plasma discharges using moveable electrodes

Minimizing the breakdown voltage and discharge current required to initiate direct in-liquid discharges, thus lowering power-source requirements and avoiding electrode ablation, is crucial for industrial applications of in-liquid plasma discharges. Here we demonstrate such considerable reductions by employing movable electrodes, without changing the electrode configuration or increasing the system complexity. The new mechanism is based on electrostatic electrode attraction resulting in a reduction in the discharge spacing by up to 6 times and facilitating a plasma initiation at lower breakdown voltages. The accumulated charges consumed by the discharge revert the electrodes to the initial positions, forming a gliding arc between the enlarged gaps and thus inhibiting current increases and electrode ablation.

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.

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

Almost all human life requires water, one of which is washing clothes. However, city people tend to use laundry services. It is necessary to treat laundry wastewater because it contains parameters that can cause environmental pollution. A promising technique has been found to treat urban wastewater, especially laundry wastewater. An electrochemical method for water treatment is known as electrocoagulation, in which a solution of an active coagulant in the form of metal ions (aluminum or iron) is introduced into a solution. In electrocoagulation, the processes of adsorption, coagulation, precipitation, and flotation taking place. This research was conducted to determine the impact of current on electrocoagulation using Al-Al, Fe-Fe, Al-Fe, Fe-Al electrodes in reducing surfactant levels in laundry wastewater with variations in the voltage used were 20 V, 30 V, 40 V, and 60 V. The results showed that the electrocoagulation process could remove surfactants in laundry wastewater. A voltage of 30 volts with Al-Al electrode configuration was used for 30 minutes to obtain optimum conditions so that it will get a surfactant effluent concentration of 5.77 mg/L with a removal efficiency of 72.89%.