Biofilm Guinea Process Of Nitrification And Denitrification Characteristics

Conventional nitrogen removal process had some questinons, long reaction step,high energy consumption .And high ammonia low carbon wastewater was difficult tocome up to the effluent standard. To solve these questions, this paper studiednitrosofication-denitrosofication process. Which took the nitrite as the terminal productof the nitrification, shorted the reaction step, attained energy conservation and highefficiency.A novel generation of biological biofilm reactor, biological turbulent bed reactor(BTBR), was used in the tests. The stability of nitrosofication process selection wasdiscussed under high ammonia or low dissolved oxygen, competition betweenheterotrophic and autotrophic bacteria was studied. The paper also dealt with thecharacteristics of denitrification started from nitrite.The experiments results showed:1.The nitrite accumulation was not stable via FA(free ammonia) because of theacclimation of the nitrite oxidizers to FA, while stable via dynamic selection because ofthe limiting substrate(DO) of growth.2.When dissolved oxygen was enough (DO≥3mg/l),the oxidation ofheterotrophic bacteria and nitrification of nitrifiers can normal occur simultaneously,but at low oxygen(DO≤1.0mg/l) nitrification was destroyed because of heterotrophicbacteria assimilated the limited oxygen,the growth of nitrifiers was influent.3.The maximum NO₃^--N was 0.08kgN/kgMLSS·d, the proper C/N was 6～8,the suitable pH was 7.1～8.1. the step of denitrification started from NO₂^- was shorterthan from NO₃^-,so the rate of the former was faster. The results as follows:r_[NO2^-]=0.079kgN/kgMLSS·d r([NO₃^-])=0.053kgN/kgMLSS·d.4.When nitrite concetration was high ,denitrification would be depressed.Temperature: 25℃, pH: around 7, NO_x^-－N concentration: less than 300mg/l, The rateof nitrite denitrification was higher; when NO_x^-－N concentration was more than300mg/l,the result reversed.