AnoxKaldnes Hybas™

Wastewater Treatment Solutions

A biological wastewater treatment solution combining activated sludge and moving bed biofilm reactor (MBBR) processes for nitrogen removal.

AnoxKaldnes Hybas Combination Process

In the AnoxKaldnes™ MBBR Hybas™ combination process, the best from two well-known technologies; activated sludge and MBBR, are combined. This process provides extra advantages that can be described by the unbelievable formula, 1 +1 = 3!

The Hybas™ combination process is a compact solution requiring little process volume to achieve both reduction of organic material and nitrogen.This process solution is often a cost effective way of upgrading an existing activated sludge system to also comprise nitrogen removal or improve the capacity of the nitrogen removal process. By adding carriers to the whole or a part of the aerated activated sludge volume, the nitrification capacity can be increased within the existing volume because high amounts of nitrifying bacteria are enriched on the carriers. BOD removal and denitrification will typically occur in the suspended phase. Thanks to the biofilm solution, the long suspended sludge age normally needed in the AS to achieve nitrification can be reduced. A reduction of the sludge concentration in the AS will also lead to less sludge load on the secondary clarifiers. Another benefit is that a short sludge age will often reduce the risk of growth of filamentous bacteria and generally, the biological activity is higher in an AS process with low sludge age than in one with a high sludge age. One can therefore achieve high denitrification activity in a Hybas™ combination process.

Factors that affect the overall design of an upgrade include media type, aeration system, dissolved oxygen concentration, effluent NH3-N concentration, basin configuration and hydraulic profiles through the basin. All these elements are necessary design factors, which have to be considered to create a well working Hybas™ system. Should one of these factors not be considered or designed properly, the overall treatment system could be adversely affected.



Process Configurations


AnoxKaldnes™ HyBAS™ for SBR

Integrated Fixed Film Activated Sludge (IFAS) Solution for SBR's
The AnoxKaldnes Hybas™ system is based on years of AnoxKaldnes moving bed biofilm experience. Hybas systems have been constructed in a variety of reactor geometries. Now, AnoxKaldnes extends this proven technology to the sequencing batch reactor (SBR). The AnoxKaldnes Hybas for SBR solution increases the capacity of a sequencing batch reactor wastewater treatment process in the same footprint as a conventional SBR. The Hybas uses engineered, moving bed media to grow and foster nitrifying bacteria, even at low SRTs and low reactor temperatures. The process allows for greater nitrification capacity for ammonia (NH3-N) removal. In addition, with recirculation, the same increase in nitrification capacity allows for both nitrification and denitrification to meet total nitrogen (TN) effluent limits. The Hybas for SBR allows for a 30% increase in treatment capacity for systems needing to meet more strict NH3-N or TN permit limits.


Features  - Hybas™ for SBR

  • AnoxKaldnes K5 Biofilm Carriers (SG>1)
  • Stainless Steel Media Retention Screens
  • Stainless Steel Medium Bubble Aeration System
  • Floating, Solids-Excluding Decanter that provides a constant discharge rate
  • Internal Recycle System
  • Blower Package
  • Instrumentation & Control (I&C)
  • Process Design and Performance Guarantees



Benefits - Hybas™ for SBR

  • Upgrades SBRs for additional ammonia or total nitrogen removal
  • Requires little site-civil construction
  • Provides a 30% capacity increase over conventional SBRs
  • Provides improved nitrification
  • Denitrifies with recirculation
  • Resists shock loads with biofilm
  • Reduces sludge production
  • Decanter provides constant decant rate that allows for UV Disinfection and Advanced Oxidation without the need for downstream EQ




  • Easy to retrofit
  • Promotes nitrification
  • Compact process
  • Improves sludge characteristics
  • More robust process
  • Less sensitive for temperature variations
  • Future expansion possible




  • Municipalities
  • Petrochemical industry


AnoxKaldnes Hybas™ Brochure (EN) (580.92 KB)
AnoxKaldnes Hybas™ Datasheet (EN) (149.22 KB)