Method for water purification

A method of controlling a wastewater treatment plant having a purifying section, said method comprising the steps of:

• a) continuously measuring one or more system parameters,
• b) determining a first control parameter on the basis of the measured values from step a) and a first control function,
• c) determining a first control action on the basis of the measured values from step a) and the first control parameter of step b) and subsequently,
• d) implementing the first control action,
• e) letting said purifying section change conditions,
• f) determining a second control parameter on the basis of the measured values from step a) and a second control function,
• g) determining a second control action on the basis of the determined control parameter and subsequently,
• h) implementing the second control action,
• i) letting the purifying section return to the conditions of step b) to d), and
• j) return to step b).

A method assuring increased biological phosphorous removal in a purifying plant with one or more aerated sections comprising the following steps:

• a) continuously determining the concentrations or the rates of formation for NH4, NO3 and PO4;
• b) determining two control parameters:
• KnN=f(NH4, NO3) and Knbiop=f(PO4, NH4) on the basis of the concentrations or the rates of formation for NH4, NO3 and PO4;
• c) implementing a control action terminating the nitrification phase when KnN and Knbiop are fulfilled;
• e) letting the purifying section reach anaerobic conditions;
• f) determining two control parameters KdnN=f(NH4, NO3) and Kdnbiop=f(PO4, NH4, NO3);
• g) determining a control action to terminate the dentrification phase when KdnN and Kdnbiop are fulfilled;
• h) implementing the determined control action;
• i) letting the purifying section return to aerobic conditions;
• and
• j) return to step b).