Nitrogen reduction in Advanced Wastewater Treatment Processes

A two stage process -
nitrification and denitrification

In biological nitrogen removal the ammonium in the municipal or industrial wastewater is converted by microorganisms to molecular nitrogen in a two-step process. First, in the nitrification step, the ammonium is oxidized to nitrate by nitrifying bacteria. Then, in the subsequent denitrification step, nitrate is reduced to molecular nitrogen by denitrifying bacteria.

A modification of an activated sludge process to include nitrogen removal usually requires larger tank volumes. In addition, the slow growth rate of nitrifying bacteria, which are responsible for the nitrification, requires a higher sludge age. Unfortunately, high sludge age can often lead to process upsets due to bulking sludge containing filamentous bacteria such as Microthrix parvicella. Therefore, design and operation of nitrogen removal processes in order to optimize nitrification and denitrification is in a sense both art and science.

Two methods

AnoxKaldnes offers two treatment technologies based on biofilm technology for efficient municipal and industrial nitrogen removal that are designed for ease of operation and minimal risks for upsets due to sludge bulking:

• MBBR™ biofilm processes operating in aerobic as well as anoxic modes.
• HYBAS™ hybrid IFAS process , a combination of biofilm and activated sludge to an advanced wastewater treatment process.

The HYBAS™ hybrid process is ideal in upgrading municipal treatment plants for nutrient removal. It is a compact solution without the need for larger volumes and it inherently suppresses the potential for bulking upset due to the growth of Microthrix parvicella.