Biological Purification of Air Polluted With Volatile Organic Compounds by Using Active Sludge Recirculation

Abstract

Various methods for removal of volatile organic compounds (VOC) from the air are applied in the world. Their selection is determined by the efficiency and costs of the method. Biofiltration is a new technology to control environmental pollutants helping to regulate emissions of VOC with unpleasant odours in to the air and working environment. When VOC are to be removed from large volumes of air, equipment of biological purification charged with active sludge is used. Such an equipment has a rather simple structure and efficiency of to 98–99 %. Active sludge as a biocharge has both a high concentration of microorganisms compared to stationary charges and good sorption features. Sorptive capacity changes when a load to active sludge is changed, and this has a negative impact on biochemical decomposition of organic substances and, at the same time, on purification efficiency. Calculation and evaluation of an optimal working mode of the equipment enable to avoid desorption of VOC in the system or to diminish it to a minimal value. In the biological air‐purification equipment sorption of an organic substance on the surface of active sludge is running at the initial stage. An organic substance is decomposed biologically only in the second stage, and oxygen dissolved in the system (in the charge) is used and VOC desorption from the system is blocked. One of the main parameters determining the biological air‐purification process and its intensity is change of the concentration of oxygen dissolved (CDO) in water phase and maintenance of its minimal value after termination of aeration (when the equipment is out of operation for some time). In operating equipment with a biocharge one more important problem is encountered ‐ the lifetime of the charge and its renewal in the equipment to maintain required concentration of the active sludge. The goal of the investigation is evaluation of purification efficiency of the equipment and the sorptive capacity of active sludge (depending on a load), selection of the working mode, uninterrupted biochemical decomposition of organic substances (based on the concentration of dissolved oxygen) when the charge is in its still state, and investigation of its biooxidating properties when a biofilter works with a biologically active charge and with an inactive charge having only sorptive properties.

Ecological Aspects of Industrial Cooling Towers Exploitation and It's Influence to Environment / Aktualūs Aušinimo Bokštų Eksploatavimo Aspektai Ir Ekologija / Актуальные Аспекты Эксплуатации Градирен И Экологические Проблемы

“…Thus the primary attention recently is given to the problems of rational usage of natural resources and protection of a surrounding atmosphere from impurities industrial enterprises (Zigmontienė and Baltrėnas 2004;Kugelevičius et al 2005).…”

Partition of Volatile Organic Compounds in Activated Sludge and Wastewater

“…1,3 Highly concentrated recirculated activated sludge has been adopted to remove VOCs from the gas stream by a Venturi tube bioreactor. 4 The water solubility and Henry's law constant of VOCs are important in mass transfer. The equilibrium of VOCs among air, wastewater, and activated sludge as it related to the effective removal of gaseous contaminants has become an important topic.…”

Разработка Новой Керамической Насадки Для Абсорбционных Аппаратов, Обладающей Большей Удельной Поверхностью

“…Они, как правило, односторонне переводят токсичные вещества в менее токсичные с большим значением предельно допустимой концентрации (ПДК), поглощая газообразные вещества жидкой фазой. Среди газообразных соединений немало летучих органических веществ (ЛОВ), которые выделяются на предприятиях химической и нефтяной промышленности (Zigmontienė, Baltrėnas 2004). В связи с этим актуальной задачей для нефтеперерабатывающих и металлургических предприятий является исключение выбросов в атмосферу с промышленными газами вредных и ядовитых веществ, прежде всего сернистого ангидрида.…”