Biological Treatment Processes: Suspended Growth vs. Attached Growth


1 Faculty of Civil Engineering, The University of Pardisan, Mazandaran, Iran

2 Biotechnology Research Lab., Faculty of Chemical Engineering, Babol University of Technology, Babol, Iran


Microorganisms play an important role in biological treatment processes. Biodegradable organic matter in wastewater would be removed completely by proper microbial consortia. The mixed culture is either generally present in the wastewater, or is introduced to the target wastewater by mixing it with domestic wastewater or sewage sludge. However, pure cultures bioprocess may be used in certain cases for the removal of specific contaminants. In favorable environmental condition, microorganisms are capable of presenting high efficiency in destruction of pollutants. If environmental conditions such as nutrition, pH, temperature, dissolved oxygen, hydraulic and sludge retention time are suitable and consistent with the nature of process, microorganisms grow and remove organic pollutants through biochemical activities. The aim of this article was to investigate the performance and mechanism of various systems of suspended and attached growth; while the detail of process in different fabricated systems was evaluated. The advantages and disadvantages of NRBC, UASFF, UAPB and normal activated sludge process were discussed. Growth kinetics and COD removal of effluents were also investigated. The result indicated the combination of fluidized and fixed film has created active biogranules which were quite faster and more efficient in treatment of industrial wastewater.


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