Study on single-stage biological nitrogen removal technique with recycling of carbon source
碳源循环单级生物脱氮技术研究

A shell and tube immobilized cell bioreactor for nitrogen removal was developed. The bioreactor consists of a bundle of parallel tubes that are made up of PVA gel which containing nitrifying and denitrifying bacteria, the ends of which are fixed on tube sheets. The tube bundle is inside a cylindrical shell with two channels, one at each end. Ammonium nitrogen wastewater is introduced into the shell side space surrounding the tubes. At the same time, air is pumped through an air stone into wastewater for nitrification. Ethanol solution is pumped into one channel, it flows through the tubes into the other channel and is withdrawn to the ethanol solution tank for recycling. The possibility and efficiency of single stage biological nitrogen removal were studied using the bioreactor and the existence of short course or nitrite route biodenitrification (ammonium nitrogen converted into nitrite first, subsequently the denitrification proceeded directly from nitrite).Coimmobilized mixed culture was proved by experiment.