One of the oldest wastewater treatment methods, trickling filters, works on the same biological principals as one of the latest treatment technologies – the MBBR. All systems relying of attached biofilms can be termed fixed-film systems. At the core, you have microbial colonies attached to a support structure. The film tends to have three distinct ecosystems inside the biofilm depending upon the location inside the biopolymer matrix supporting the colony.
The biofilm acts to protect the microbes from toxic influent compounds, pH swings, hydraulic washout, and other factors that would kill individual microbial cells. Much like floc in suspending growth systems, the fixed-film biomass consists of living bacteria, inorganic materials, extracellular polymers (the glue), and adsorbed organics. The percent of the mass that is truly living microbes depends upon influent makeup, organic concentration, and biofilm sloughing rates.
The fixed film system overcomes solids seperation problems often seen in suspended growth system’s secondary clarifiers. In effect, the fixed film allows for a higher MLSS (up to 3,000 mg/L higher) than a comparable suspended growth system. This directly translates to:
Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.
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