Wastewater Reclamation Using a Microplasma Ozone Source--E. Coli and Organic Dye Destruction.

The interest in using ozone is increasing, because it is effective, can be generated on site, does not require handing chemicals, and leaves no chemical residue after use.  It is used for a many applications including water purification, decoloration, oxidation of organic pollutants, and removal of suspended solids (turbidity). Among other uses, it is used for food processing and preservation to inhibit bacterial growth and for sanitizing food processing materials and surfaces. Ozone also finds use in the remediation of contaminated soils where the primary pollutants are aromatic hydrocarbons and phenolic compounds.

A new ozone microplasma water purification system using patentend technology from KWJ Engineering is designed and investigated.  The utility of the proposed system is specifically relevant for processing potable water as well as providing an in-situ source of the highly effective disinfectant ozone using minimal energy and chemical reactants.

A basic design was developed using a copper wire within a glass capillary wrapped with platinum or copper wire.  When a high voltage alternating current is applied to the electrodes, a plasma is created on the outside of the platinum or copper wire encircling the glass capillary. The microplasmas generate 50-80 ppm of ozone at 0.5 L/min, which is then mixed with the contaminated water. Tests were conducted on volumes of 35-50 mL, but the method is scalable for larger volumes. The ozonating methods were tested on an organic dye and on E. coli cultures.  The destruction of the organic dye over time was measured with a uv-vis diode array spectrophotometer.  A colony forming unit counting process with serial dilutions was used to determine effective rates of ozonation for destruction of E. coli. The results show a dramatic decrease in organic content and in living bacteria.