TECHNOLOGY FOCUS - POLYMERS - Preferred Components: (F1) Has density of 10 - 60 kg/m3 and porosity of 30 - 100%. (C1) Contains 1 - 100% of (P1) having a size of 0.1 - 60 meshes. (F1) Is polyurethane foams.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: (P1) Are activated carbon particles, diatomite particles or zeolite particles. When influent contains ammonia and/or nitrogen containing compounds, (P1) are zeolite particles and when influent has color which is at least two times greater than that of the effluent, (P1) are activated carbon particles. (C1) Is cubic or spherical body with a volume of 8 - 125 cm3. The reactor contains several (C1) so that a total volume of (C1) is 80% of a capacity of the reactor. Preferred Method: (P1) And (F1) are mixed together in an aqueous solution so that (P1) are entrapped in the pores of the (F1). The aqueous solution is the influent introduced in the reactor. The mixing is carried by, bubbles created in bottom of the reactor. EXAMPLE - Two sets of reactors were made up of polyacrylate. Polyurethane (PU) foams were used as porous carriers having volume of 1 cm3. PU Foams were added to the two reactors with additional amount of 80%. One of the two reactors was provided with activated carbon powder (5 g) (test reactor) and other reactor (control) was devoid of the activated carbon powder. The activated carbon powder was added to the test reactor in the middle of the addition of the porous carriers to the reactor. After introduction of the synthetic wastewater (as influent) prepared with AO-7 as primary component and a minute amount of urea, phosphate and ferric chloride into the reactor, the activated carbon powder was driven by air bubbles from the aerating device to entrap in the pores of the PU foam carriers. The microorganism was seeded in the two reactors. Each reactor was provided with 2100 mg of sludge. The influent was introduced from the bottom of the reactor. It was observed that the wastewater color of the test was effectively reduced from 1000 - 2500 ADMI to less than 550 ADMI whereas in case of control the color of the influent did not change.