Volume reduction method for entrapped immobilized carrier, entrapped immobilized carrier, water quality purification method and device for manufacturing entrapped immobilized carrier

The invention provides a reducing method of an immobilized carrier, an immobilized carrier, a method for purifying water and a manufacturing apparatus of immobilized carrier, particularly a technology that reduces volume of a carrier immobilized by hydrogel-containing microorganism and used for purifying water quality for breeding ornamental fish. Under the condition that the activity of microorganism is not reduced, the reducing method of an immobilized carrier of the invention retains a uniform shape of carrier, in the mean time, effectively reduces volume of the carrier. That is a reducing method of an immobilized carrier, which immobilizes microorganism in a fixed material, comprising: reducing volume of the immobilized carrier through carrying out air blasting desiccation so that skin temperature of said immobilized carrier may be 10 to 40 degrees centigrade.