NOVELTY - Obtaining Rhodococcus strain C3 involves taking sample (1%) of activated sludge inoculum and performing wastewater biological treatment on a shaking culture medium. Certain amount of culture medium is then transferred to the phenol liquid culture medium to improve the phenol concentration to 1000mg/L. The cell is treated with inorganic medium after the phenol concentration reaches 1000mg/L. Dilution coating and scribing methods are performed in the medium plates and phenol is isolated as sole carbon and energy strain.    USE - Method for obtaining Rhodococcus strain C3 used for treating organic pollutants in coking waste water, oil refining waste water or tar processing waste water (claimed).    DETAILED DESCRIPTION - Obtaining Rhodococcus strain C3 involves taking sample (1%) of activated sludge inoculum and performing wastewater biological treatment on a shaking culture medium. Certain amount of culture medium is then transferred to the phenol liquid culture medium to improve the phenol concentration to 1000mg/L. The cell is treated with inorganic medium after the phenol concentration reaches 1000mg/L. Dilution coating and scribing methods are performed in the medium plates and phenol is isolated as sole carbon and energy strain. The liquid enrichment medium comprises peptone, beef extract, sodium chloride, deionized water and phenol, where the mass ratio of peptone, beef extract, sodium chloride and deionized water 10:3:5:1000, and phenol is added in a required concentration. The inorganic salt liquid medium comprises phenol as sole carbon source, along with monopotassium phosphate, dipotassium phosphate, magnesium sulfate, calcium chloride, iron(II) sulfate heptahydrate, manganese(II) Sulfate Monohydrate, phenol and distilled water, where the mass ratio of monopotassium phosphate, dipotassium phosphate, magnesium sulfate, calcium chloride, iron(II) sulfate heptahydrate and manganese(II) Sulfate Monohydrate is 0.5:0.5:1:0.2:0.2:0.01:0.01. The strain is identified as 16SrDNA Rhodococcus species, Gram-positive, and positive for urease, catalase and oxidase. The strain shows negative results for Voges-Proskauer test and methyl red test. The single colonies on Leuria Bertani medium which having yellowish translucent appearance and moist texture are easily selected. The C3 strain comprises phenol, pyridine and o-cresol as a carbon source, and an inorganic salt in the liquid medium is capable of degrading 1000mg/L phenol. An INDEPENDENT CLAIM is included for a method for preparing microbial agent, which involves:    (A) inoculating Rhodococcus strain C3 into the enrichment medium and culturing at a temperature of 30 degrees C and stirring speed of 200 rotations per minute (rpm) for 24-48 hours;    (B) performing centrifugation at 7000rpm for 3-5 minutes to obtain bacterial cells of logarithmic phase and washing 2-3 times with phosphoric acid salt buffer solution;    (C) centrifuging the broth by adding activated carbon for adsorption in an amount of 3-10 wt.%;    (D) adding polyvinyl alcohol (PVA) in water in the volume ratio of 1:8-10, and dissolving completely at 90 degrees C in a water bath;    (E) mixing PVA with sodium alginate, calcium carbonate and silica in the weight ratio of 10:3-6:35:0.2-0.5 to obtain PVA-sodium alginate gel;    (F) adding bacteria to the PVA-sodium alginate gel, mixing uniformly, and adding activated carbon to obtain a cell suspension of PVA-sodium alginate;    (G) adding low boric acid solution containing calcium chloride (3-5%) at a neutral pH and stirring continuously;    (H) performing immobilized crosslinked at 4-6 degrees C for 24-90 hours after the removal to obtain immobilized particles; and    (I) adding dipotassium phosphate as a curing agent to the immobilized particles and washing 2-3 times with deionized water to obtain immobilized microbial agent.