Biological Treatment
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Example for 2.000 Residents (7 MB)

Biological Treatment

Biological treatment is a more natural wastewater treatment process than other waste water treatment methods. Microorganisms feed on the complex materials present in the wastewater and turn them into unharmful substances. The point of this process is to reduce the organic substances measured by Biological Oxygen Demand (BOD) level.

Elimination of the organic load in biological process is only possible if more oxygen is supplied than consumed by the microorganisms. With high-loaded wastewaters and conventional aeration systems, the activated sludge process quite often meets its performance limits, since the possibility for oxygenation is physically restricted. Advanced bioreactor solution by INNOCHEM is a development of the standard activated sludge process, trying to improve the disadvantages of the conventional process, especially concerning the insufficient oxygen utilization.

Comparison with classical activated sludge process

Instead of the conventional low and open tanks made of reinforced concrete, closed plastic or steel containers and gas-atomizing nozzles for aeration are applied. These gas-atomizing nozzles use the kinetic energy of the liquid jet - the waste-water to be cleaned is used as driving jet - to separate the air stream into extremely fine air bubbles so that the microorganisms are optimally supplied with oxygen and thus their living conditions are as optimal as possible. The plant shows an attractive ratio of energy demand and liquid volume. Another advantage is the controllable intermixing air/liquid ratio which constantly ensures optimal degradation efficiency for all biological-organic material. Surplus sludge production decreases to max. 10 % compared to standard wastewater treatment plants.

Characteristics and Benefits

  • Volumetric load: 8 to 15 kg COD/(m³ day)
  • Hydraulic retention time: 30 to 90 minutes
  • Mixed liquor suspended solid (MLSS): 10 and 20 g/l
  • Utilization of oxygen: 80 to 90 %
  • Degradation of BOD: more than 98 %
  • Excess sludge production: 0,032 bis 0,05 kg dry weight per kg COD

The system is characterized by high oxygen transport rate hence footprint requirement is merely 0,2 m² per Population Equivalent.

Economic Efficiency

Investment costs of biological treatment systems are determined by the organic load (BOD and COD) and the desired effluent quality, because these parameters influence directly the necessary volume of the bioreactor.

Moreover the volume is swayed by operational parameters like MLSS as well as the geometry of the bioreactor and the aeration system.