RESEARCH OF DISPERSE COMPOSITION OF AIR-AND-WATER MIX GENERATED BY EJECTOR AERATION SYSTEM DURING WASTEWATER FLOATATION TREATMENT
Abstract and keywords
Abstract (English):
The process of waste water treatment by floatation using ejector system of aeration has been considered in this paper. The system’s main shortcoming has been noted: receipt of large bubbles with a diameter about 1 mm, that not always allows get a high performance of cleaning. It has been noted that the most effectively the process of floatation treatment for industrial sewage from fine pollutions is performed when the bubbles’ sizes are less than 100 microns, and when there is a big range of pollutions in water it is reasonable to receive the bubbles with a wide disperse structure. The carried-out overview of Russian and foreign sources has demonstrated that the main shortcomings of existing dispersion devices used for crushing of the bubbles generated by the ejector is insufficient dispersion extent in case of low gas content, work instability, technology complexity. For sewage treatment process intensification and remedial action of the existing devices has been offered a combined aeration system consisting of ejector and original dispersing device. On laboratory installation have been conducted experimental studies on determination of disperse composition for air-and-water mix generated by the offered aeration system. The received results confirm a possibility for receipt of fine bubbles in the range of 20–300 microns with a degree of bubbles of fraction less than 100 microns up to 80 %, and with an average diameter of 60–80 microns. A feature of the bubbles’ disperse structure has been noted: allocation from it several groups of bubbles with different values of average diameters. This feature can be used for intensification of process for water treatment from pollutions with various floatability degrees. Dependences of researched characteristics on dispersant’s diameter and height have been presented. They allow perform a choice of dispersant’s geometrical parameters for receipt of the air-and-water mix’s required disperse composition aimed to management of floatation process.

Keywords:
floatation sewage treatment, ejector, dispersant, aeration system, bubble diameter, waste water purification efficiency
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1. Введение

Известно, что эффективность процесса флотационной очистки воды в значительной степени зависит от способов и устройств аэрации воды [1–3]. Для этих целей применяется несколько способов и множество различных аппаратов и устройств. Аэрирование воды при помощи эжекторных устройств получило широкое распространение благодаря простоте их конструкции, высокой надежности, экономичности применения [4, 5]. Однако применение эжекционной системы аэрации при флотационной очистке сточных вод не так широко распространено в связи с недостатками, основной из которых — получение крупных пузырьков воздуха диаметром около 1 мм, в то время как оптимальный диаметр пузырька для извлечения тонкодисперсных загрязнений составляет 50–90 мкм [3]. Следует отметить, что в случае присутствия в сточной воде большого спектра загрязнений, причем каждое загрязнение наиболее эффективно удаляется пузырьком определенного диаметра, целесообразно получать пузырьки широкого дисперсного состава. Поэтому для интенсификации процесса очистки воды с использованием эжекторов предлагается использовать дополнительные устройства диспергирования.

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