Water Purification by Plasmas: Which Reactors are Most Energy Efficient?

Abstract

Decomposition of toxic organic compounds is a major environmental problem. Increasingly, research is being conducted to use plasmas to decompose these wastes in water, as it is simple, effective and does not require the addition of other chemical agents. Different groups have used varied reactor designs. This study calculates and compares relative energy yields of about 27 major types of plasma reactors. The results reveal dramatic differences in the energy yields, up to five orders of magnitude. The most efficient are pulse powered reactors, in which plasma is formed in gas phase and the waste solution sprayed into it. Factors that account for this improved energy yield are discussed. This study will help narrow down efficient reactors for further studies, development and commercial uses.

A review of plasma–liquid interactions for nanomaterial synthesis

“…But the studies on physical and chemical processes in the PLIs have attracted researchers' attention just in recent decades due to the beneficial applications in water treatment [16][17][18][19], plasma medicine [21][22][23][24], the NM synthesis [42][43][44][45][46][47][48][49], surface engineering [62][63][64][65] etc.…”

A Review of Combined Advanced Oxidation Technologies for the Removal of Organic Pollutants from Water

“…Although, the energy yield of each reactor vary over a wide range due to difference in the reactor type experiment conditions used by the different research group globally. Their findings indicate a dramatic variation in the efficiency of different types of plasma reactors and as such the difference is close to 5 orders of magnitude (Malik 2010). In same vein, limited data on energy yield of plasma reactors exist because of the differences in the reactor type used by various research group globally.…”

“…Electrohydraulic discharge system is regarded as one of the advanced oxidation technologies widely applied for water and wastewater treatment to inactivate microbes and degrade toxic or hazardous pollutants (Malik 2010;Jiang et al 2014). There are various forms of electrical discharge plasma produced either in water or above water such as in gas phase contacting the liquid.…”

“…There are different categories of electrical discharge systems for water treatment depending on the relative magnitude of http://repository.uwc.ac.za 7 applied energy in the system. The efficiency or reactivity of the plasma generation systems vary with respect to reactor configuration, energy yield, and sometimes depend on the input energy, liquid properties and excitation voltage (Malik 2010;Jiang et al 2014). Apart from the above factors, energy yield often depends on the electron density, pollutants structure, nature and concentration of pollutants, temperature, electrode material, the extent of transformed products, solution pH and sometimes conductivity.…”

“…Each of these has been extensively reviewed. For more information, the readers are referred to the following review article (Locke et al 2006;Malik 2010). In electrohydraulic discharge techniques, the introduction of air or pure oxygen into the reactor produces ozone.…”