NOVELTY - Biological agent is prepared by mixing microbial composition and carrier in a weight ratio of 1:1-2:1. The microbial composition comprises 10 pts. wt. yeast, 7 pts. wt. Bacillus subtilis, 6 pts. wt. B.megaterium, 5 pts. wt. denitrifying bacteria, 5 pts. wt. Pseudomonas aeruginosa, 4 pts. wt. Rhodococcus, and 3 pts. wt. Phanerochaete chrysosporium. The carrier is chitosan.    USE - The biological agent is useful for treating wastewater (claimed).    ADVANTAGE - The agent is environmentally-friendly.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method for using the agent, which involves (a) obtaining fermentation broth containing glutamic acid, subjecting broth to high-speed rotating machine, separating bacterial protein from broth by rotating at 4000-5000 revolutions per minute (rpm) and collecting precipitate, (b) adding warm water to precipitate, mixing uniformly, adjusting solid content to 15%, adjusting pH to 6-7 using lime, adding 1/10 volume of seed culture liquid, stirring uniformly, controlling temperature of solution to 32-34 degrees C, fermenting mixture by providing intermittent aeration, and culturing 24 hours to obtain fermentation broth, where the seed culture liquid is obtained by mixing Saccharomyces cerevisiae (CCTCC M208110) and Lactobacillus plantarum (CCTCC M208151) in a volume ratio of 3:1, and the concentration of S.cerevisiae and L.plantarum is 1x 108 cells/ml, (c) sterilizing fermented broth, adding sterilized broth into tank, adding 1.5 %mass activated carbon into tank, performing decolorization at 45-50 degrees C for 30 minutes, concentrating decolorized mixture under vacuum condition at 60-70 degrees C, and -0.1 kPa to obtain crude crystals, purifying and isolating crystals, subjecting ion exchange, performing secondary crystallization, separating, and drying to obtain glutamic acid, and (d) collecting wastewater after extraction process, separating solid and liquid substance naturally, collecting sediment and supernatant, discharging into sewage treatment system, and adding biological agent into system.