Experimental Study on Recirculation Ratio and Related Factors in Biological Nitrification/Denitrification Process for Onsite Household Wastewater Treatment Facilities : Part 1-Relation between Recirculation, Redox Potential and Denitrification

Abstract

The removal of nitrogen compounds in wastewater has been required formerly by even to the small-scale onsite household wastewater treatment facilities. This experimental study aimed to confirm on the some planning factors in biological denitrification process for such facilities. This paper stated on the following items. 1. Mutual relations between pH, ORP values and nitrification/denitrification reaction. 2. Required and desirable characteristics of the influent and recirculating water. 3. Interaction between recirculation ratio (quantity) and denitrification degree. The following results were obtained in this experiment. It is desirable to keep about over +200mV ORP for nitrification process, and under about +50mV for denitrification process. Adequate recirculation Ratio will be about 4.