Efficiency of gas discharge methods for odor control in municipal wastewater transportation and treatment systems

В процессе транспортировки и очистки сточных вод в воздух выделяются дурнопахнущие вещества, среди которых одним из наиболее трудноудаляемых является сероводород. Для очистки воздуха от дурнопахнущих веществ используются различные методы, в том числе газоразрядные (плазменные, ионизационные), которые хорошо зарекомендовали себя в других областях промышленности. Вентиляционные выбросы, образующиеся при обработке и очистке сточных вод, имеют ряд особенностей: высокая влажность, высокая концентрация сероводорода, потенциальная взрывоопасность. Эти свойства ограничивают возможность использования газоразрядных методов для очистки данного типа вентиляционных выбросов. Описывается специфика применения газоразрядных методов при очистке воздуха на очистных сооружениях канализации и канализационных насосных станциях. Приведены возникающие при этом технические сложности. In the process of wastewater transportation and treatment malodorous substances are released into the air; among them hydrogen sulfide being one of the most difficult to remove. Various methods are used to remove malodorous substances from the air, including gas-discharge (plasma, ionization) methods that have proven remarkably effective in other industries. Vent emissions generated during wastewater treatment are specified by high humidity, high concentration of hydrogen sulfide, potential explosion hazard. These properties limit the possible use of gas discharge methods for the purification of this type of vent emissions. The specificity of applying gas discharge methods for air purification at the wastewater treatment facilities and wastewater pumping stations is described. The arising technical difficulties are presented.

EXPERIMENTAL TESTING BENCH FOR THE DIAGNOSTICS OF PLASMA GENERATED BY PULSED GUNS WITH THE DIELECTRIC SURFACE BREAKDOWN

The experimental testing bench “ETB-PG” was designed to study the operation of plasma guns. The constructional design of plasma guns with replaceable dielectric operating on the surface sparkover basis has been proposed. Discharge currents and voltages under atmospheric and vacuum conditions have been determined. The two types of discharges were detected in the pressure range varying from the atmospheric value to 10-5 Torr. An experimental Paschen curve has been plotted. A statistical dependence of the types of discharges on the number of pulses, the pressure in the chamber, and the breakdown voltage has been established. The results of optical studies of the plasma flow generated by plasma guns in the vacuum of 2∙10-4 to 2∙10-5 Torr have been presented. The propagation velocity of the plasma flow in axial and radial directions has been measured. The glow time of the injected plasma was determined for different types of the discharges. The spectrograms of the composition and degree of the plasma ionization have been obtained.

Author Correction: Surface acoustic wave nebulization improves compound selectivity of low-temperature plasma ionization for mass spectrometry

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Surface acoustic wave nebulization improves compound selectivity of low-temperature plasma ionization for mass spectrometry

Mass spectrometry coupled to low-temperature plasma ionization (LTPI) allows for immediate and easy analysis of compounds from the surface of a sample at ambient conditions. The efficiency of this process, however, strongly depends on the successful desorption of the analyte from the surface to the gas phase. Whilst conventional sample heating can improve analyte desorption, heating is not desirable with respect to the stability of thermally labile analytes. In this study using aromatic amines as model compounds, we demonstrate that (1) surface acoustic wave nebulization (SAWN) can significantly improve compound desorption for LTPI without heating the sample. Furthermore, (2) SAWN-assisted LTPI shows a response enhancement up to a factor of 8 for polar compounds such as aminophenols and phenylenediamines suggesting a paradigm shift in the ionization mechanism. Additional assets of the new technique demonstrated here are (3) a reduced analyte selectivity (the interquartile range of the response decreased by a factor of 7)—a significant benefit in non-targeted analysis of complex samples—and (4) the possibility for automated online monitoring using an autosampler. Finally, (5) the small size of the microfluidic SAWN-chip enables the implementation of the method into miniaturized, mobile LTPI probes.