TECHNOLOGY FOCUS - PHARMACEUTICALS - Preferred Method: The method further involves inoculating the bacteria in the container; introducing a hydrophobic substrate into the container; allowing bacteria to couple to the hydrophobic substrate; introducing the preserved bacteria into bacteria generator; introducing the preserved bacteria into a wastewater treatment system; introducing a flow of nutrients for at least one of the bacteria into the container; stopping flow of nutrients for at least one of the bacteria into the container; allowing weaker bacteria to die and allowing hardier bacteria to enter a starvation phase; reviving the preserved bacteria; and adding at least one nutrient to the preserved bacteria to revive the preserved bacteria. The step of preserving a portion of the bacteria involves mixing alginate into a first aqueous solution; adding the hydrophobic substrate comprising bacteria in the starvation phase to the alginate solution; adding the hydrophobic substrate comprising bacteria and alginate into a second aqueous solution containing calcium ions; and allowing a hydrophobic substrate comprising immobilized bacteria to form. The method for preserving bacteria involves: introducing at least one bacteria to a first bacteria generator; reproducing at least one of the bacteria; allowing a portion of at least one bacteria to enter starvation phase; preserving the portion of bacteria in the starvation phase; adding a part of preserved bacteria into second bacteria generator; allowing the preserved bacteria to incubate in the second generator; providing a portion of the bacteria in the second generator to a container containing a substrate; allowing the provided bacteria from the second generator to couple to the substrate in the container to form a biofilm; and optionally introducing wastewater into the container, and reducing amount of contaminant in the wastewater using the biofilm. Preferred Components: The container comprises bacteria generator. The introduced bacteria comprises bacteria of genus Pseudomonas, Bacillus, Enterobacter, Zoogloea, Agrobacterium, Gordonia and Caulobacter (preferably Pseudomonas stutzeri, Pseudomonas putida, Bacillus subtilis, Agrobacterium species, Enterobacter cloacae, Zoogloea species, Gordonia species, Caulobacter vibrioides and/or Caulobacter crescentus). EXAMPLE - Bacteria of genus Agrobacterium, Bacillus, Caulobacter, Enterobacter, Gordonia, Zoogloea and Pseudomonas was incubated at 25 to approximately 30degreesC in a nutrient broth. Bacteria of genus Agrobacterium and Zoogloea were incubated at 26degreesC. The bacteria were incubated for 24-72 hours without the addition of an additional amount of nutrients. Bacteria of genus Agrobacterium, Bacillus, Enterobacter, and Pseudomonas was incubated for 24-48 hours. Bacteria of genus Caulobacter and Gordonia were incubated for 48-72 hours. Bacteria were monitored to determine whether exponential growth ceased and bacteria had entered the starvation phase. It was observed that the bacteria had entered the starvation phase. The bacteria were then preserved by using sodium alginate. Sodium alginate (40 g) was mixed into an aqueous solution to form solution more viscous than water. The alginate solution was autoclaved at 121degreesC for 30 minutes. The alginate solution was cooled. The bacteria in the starvation phase prepared above, was added to the alginate solution to form bacteria-alginate mixture. The bacteria-alginate solution was agitated. The bacteria-alginate solution was added in drops into 0.55M calcium chloride solution (2 l). The calcium chloride solution was mixed continuously. Particles, with a length and a width of approximately 5 mm were formed in the calcium chloride solution. The bacteria-alginate particles were filtered. The particles were then dried and stored.