The MBF shows to be very reliable for hosting aerated biological processes. Furthermore maintenance and operation attendance is low, which makes it particularly suitable for smaller works, which tend to be unattended. A thin biofilm on top of the sand grains is developed within the bioreactor. This enables a stable nitrifying population to be maintained in the reactor under varying process conditions. Shock loadings are therefore handled effectively. Furthermore the continuous sand circulation allows the biomass to nitrify even under low loading conditions.
Filtrate 95% ammonia levels of less than 1 mg/l ammonia-N are achieved consistently at conversion rates up to 0.7 kg N/(m3.d). Even at water temperatures as low as 5 °C the system proves efficient.
Filter bed aeration
The required aeration within the filter is established by using a rigid aeration grid. The air bubbles are released in the bottom of the filter bed, and move upward. Oxygen uptake by the biomass on the sand grains is highly efficient. Hence an energy efficient biological process is achieved.