It is a plastic-injected, semi-circular, fishnet-like spherical structure. The center is filled with plastic woven threads or small pieces of sponge. In the biochemical treatment of sewage, it features a fully three-dimensional structure, a large specific surface area, direct placement without fixation, easy biofilm formation, and no clogging. The all-plastic structural unit filler has A/O and A2/O hydrolysis–aerobic functions, produces very little excess sludge, and has a long service life.