Synthetic wastewater treatments in internal packed-bed cell recycle system

Abstract

The technological development gave not only comfortable life but also many wastes. Because of environmental pollution become aggravated, a lot of people claim the protection of environment in all sorts of fields. And Korea entered waster-stressed nation at 2006. We efforts to improve and maintain water environment. This research was studied domestic wastewater treatment to protect pollution of water by sewages. Common methods have problems and it was studied that the method of recycling activated sludge. However, it has another problems and higher operating cost. Therefore, new wastewater treatment systems of efficient and simple methods needs. This research adopted the internal packed-bed system that modified common treatment system with aeration and external packed-bed. Various bed types were used to solve the problem of pressure drop in packed-bed. As a result, short bed type with large surface contacted wastewater was more stable than long bed type, because of the effect of pressure drop was few. Experiment was performed at four retention time (2, 4, 8, 12 hours) and three organic concentrations (560, 1300, 5000 mg/l COD). And a microorganism was obtained from an activated sludge sewage disposal plant in Daejeon. The COD removal efficiency reached to 90 % on influent concentration of 1300 mg/l, and to 37 % on influent concentration of 5000 mg/l with optimum retention time 8 hours. Removal efficiency with high-concentration wastewater was very lower than desired quality. Because of low concentration of oxygen inhibited cell growth. To improve removal efficiency, dissolved oxygen in wastewater was increased by increased agitation speed or feed concentration of oxygen. Removal efficiency of 77 %, 51 % was achieved by 45 % O2 feeding, 500 rpm agitation speed in high-concentration wastewater. Also, removal efficiency was improved to 97% and it can be treat the carbon source of 3.26 kg /day in 560 mg/l COD with retention time 4 hours. However, retention t...