The marine bio-chemical sewage treatment device consists of three cabinets, namely the aeration cabinet, the contact cabinet, and the sedimentation and disinfection cabinet.

In the aeration cabinet, the activated sludge flocs mainly composed of aerobic bacteria form flocs like cotton floss with viscosity to adsorb organic substances, and under the condition of oxygen charging, the organic substances are digested into harmless carbon dioxide and water, while the activated sludge is reproduced; in the contact oxidation chamber, there is soft filler hung as a biofilm, and the organic substances are further digested; the accumulated activated sludge sediment in the sedimentation cabinet is then returned to the aeration cabinet as a strain for reproduction and reprocessing.

The sewage that has undergone clarification treatment finally enters the disinfection cabinet to be sterilized with chlorine-containing drugs, and then is discharged outboard by the discharge pump.