Patent EP-2196438-B1 (EP)
Inventor: BASSFELD ANDREAS
IPC: C02F3/30
Filed: 2009-12-11
Granted: 2013-11-20
Abstract: The method for load dependent dynamic adaptation of nitrification- or denitrification phase during biological sewage processing in main stream process through a load dependent regulation for a cascade-shaped basin arrangement with pre-connected denitrification with a continuously processing nitrification zone under use of an aeration device, comprises carrying out an automatic switching to regulation basin or basin section from actual denitrification phase into a nitrification phase in the sense of an interrupted operation of a blower. The method for load dependent dynamic adaptation of nitrification- or denitrification phase during biological sewage processing in main stream process through a load dependent regulation for a cascade-shaped basin arrangement with pre-connected denitrification with a continuously processing nitrification zone under use of an aeration device, comprises carrying out an automatic switching to regulation basin or basin section from actual denitrification phase into a nitrification phase in the sense of an interrupted operation of a blower, when the end of ventilated phase is recognized in another basin or basin section and the denitrification phase is initiated. The oxygen entry of the aeration device is brought to load dependent single basin or basin sections through real time analysis of process technical and energetically relevant parameters and an intermittent operation of the single basin or basin section is reached in free alternation. The oxygen entry of a permanently operating aeration device such as turbo blower is brought through a control unit of the individual basin or basin section under use of fuzzy pattern technology. The time for the aeration and deactivation of the aeration depends by the temperature, pH value, redox potential, dissolved oxygen, ammonium content, nitrite content, nitrate content, air volume stream or air mass stream and/or the aeration power or power absorption. The automatic switching is carried out in the denitrification phase, when the requested oxygen profile has a minimum oxygen desired value over a certain time, where nitrate concentration in the recirculation is influenced in load-dependent manner through a control regulation. A clear improvement of the denitrification takes place within the upstream denitrification zone through the strict avoidance of a procrastination of dissolved oxygen from the respective nitrification zone. A noticeable rising of the drying substance content is caused during the denitrification phase in the basin or basin section and an increased degradation capacity is obtained before beginning of the nitrification phase. A gradual reduction of the recirculation is carried out in failing of the recognition of the end of the denitrification in the nitrification zone to be regulated. A significant increase of ammonium or pH value in inflow or outflow causes the change of the nitrification- and/or denitrification phase. The denitrification phase is determined in the nitrification zone to be regulated, when the inflow or outflow volume stream of the clarification plant exceeds a predetermined value or the significant increase of ammonium nitrate or pH value in inflow or outflow is detected. The initiation of a passive or active dosage of external or internal carbon source for supporting the denitrification is carried out in the plant with unfavorable carbon/nitrogen ratio. A part of the nitrification zone is aerated by a ceramic aerator and is completely disengaged in a further part area for a certain time, where the air supply of minimal volume stream is limited in a further part area for a certain time. The minimal volume stream obtains from the minimum opening angle of the air controller so that the ratios of the simultaneous denitrification adjust. The entry of oxygen takes place for the nitrification zone or subsequently over pure oxygen gassing or by electrochemical way.