Activated sludge method: aerobic form of wastewater treatment by the biochemical metabolism of suspended biological communities.
In the process of growth and reproduction, microorganisms can form colloidal masses with large surface area, which can flocculate and adsorb a large amount of suspended colloidal or dissolved pollutants of wastewater, and absorb these substances into the cells, and completely oxidize these substances with the participation of oxygen to release energy, CO2 and H2O. the sludge concentration of activated sludge method is generally 4g/L.
Biofilm method: Microorganisms are attached to the surface of the filler to form a gelatinous connected biofilm. Biofilm generally has a fluffy flocculent structure with more micropores and a large surface area, which has a strong adsorption effect and is conducive to further decomposition and utilization of these adsorbed organic matter by microorganisms.
In the treatment process, the flow of water and air stirring make the biofilm surface and water contact constantly, organic pollutants and dissolved oxygen in the wastewater are adsorbed by the biofilm, and the microorganisms on the biofilm continuously decompose these organic substances, while oxidizing and decomposing the organic substances, the biofilm itself is constantly metabolized, and the aging biofilm is shed and brought out from the biological treatment facility and separated from the water in the sedimentation tank. Separation The sludge concentration of biofilm method is generally 6-8g/L.
The main difference between the biofilm method and the activated sludge method is that the microorganisms of the former do not need a filler carrier and the biological sludge is suspended, while the microorganisms of the latter are fixed on the filler.
However, the mechanism of treating wastewater and purifying water quality is the same. The biological sludge of both is aerobic activated sludge, and the composition of sludge also has some similarity.
In addition, the microorganisms in the biofilm method, being fixed on the filler, can form a more stable ecosystem, and their living energy and consuming energy are not as large as those in the activated sludge method, so the residual sludge of the biofilm method is less than that of the activated sludge method.