가압호기조를 이용한 생물학적 하폐수처리

Abstract

The biological wastewater treatment is a process of removing dissolved organic matter and solids from the wastewater and purifying it into clean water. In particular, the specific and simultaneous treatment of nitrogen and phosphorus is called an advanced biological wastewater treatment process. In this study, a new type of air supplying system using an ejector and a pressurized oxic tank was applied to replace conventional blower and air diffusers that are essential components for an advanced biological wastewater treatment. The application of the pressurized oxic tank improved the oxygen transfer efficiency, thereby enabling efficient removal of nitrogen and organic matter, and it also allowed the internal nitrate recirculation to be omitted. Therefore, it was expected to reduce energy consumption, initial installation and maintenance costs. For organic material oxidation and nitrification, an ejector was used to increase the dissolved rate of oxygen in the pressurized oxic tank, which improved the treatment efficiency even in a short hydraulic retention time (HRT). Dissolved air in the pressurized oxic tank(2~5kgf/㎠) is transferred to the following air bubble removal tanks, and biological pollutant removal can be performed using the leftover dissolved oxygen by microbial sludge attached to the sponge media in the air bubble removing tank. Stable microbial activity was confirmed in the pressurized oxic tank where dissolved oxygen (DO) concentration was maintained at a high level to sufficiently conduct organic matter oxidation and nitrification. As a result, it was possible to continuously treat polluted water by separating sludge from air in the air bubble removing tank. In general, it is difficult to control DO concentration and solid-liquid separation because of bounded dissolved air. Therefore, a new type of air supplying system was developed to overcome these constraints. However, there are still many unknown parameters in the suggested system, so sophisticated performance evaluation should be further performed for understanding exact ejector efficiency and nitrogen and phosphorous removal behaviors.