1) Every chemical is a highly targeted product, which may fail when it meets other chemicals, while biological agents have spectral characteristics in removing pollutants.
2) Chemical products can temporarily eliminate some harmful substances and cover up the smell, and lack of them can't stop the production of harmful substances.
3) After using chemical products, there will be residues in the water, which may lead to secondary pollution. Biological agents contain natural microorganisms and do not contain pathogenic bacteria and pathogens. Catalyzed by enzymes, these microorganisms feed on organic nutrients in sewage. When the sewage is purified, these microorganisms will gradually decrease with the decrease of pollutants until they become extinct.
4) non-toxic, non-corrosive, easy to use, basically no need to increase equipment or engineering, saving capital investment.
Biofilm treatment of sewage is a kind of aerobic biological treatment technology of sewage, which is parallel to activated sludge process. The essence of this treatment method is to make microorganisms related to bacteria and fungi and micro-animals such as protozoa and metazoa attach to filter materials or some carriers to grow and reproduce, and form membrane-like biological sludge-biofilm on them. When the sewage comes into contact with the biofilm, the organic pollutants in the sewage are absorbed by the microorganisms on the biofilm as nutrients, the sewage is purified, and the microorganisms themselves multiply in large numbers. Wastewater biofilm treatment is an ancient and developing wastewater biological treatment technology. Up to now, the processes of biofilm treatment mainly include biofilter (common biofilter, high-load biofilter and tower biofilter), biological rotary table, biological contact oxidation equipment, biological fluidized bed, aerated biofilter (BAF) and its derivative processes, and moving bed biofilm reactor (MBBR).