In the initial stage of biofilm, the surface of the filler layer should be gradually covered by film-like sludge (biofilm) by the low-load influent mode.

Do, temperature, pH value, microbial growth status and species in the biological contact oxidation tank should be strictly monitored.

The thickness of the biofilm should be strictly controlled, and the aerobic layer thickness should be kept about 2mm. The excessive growth of the anaerobic layer should be avoided, and the biofilm peeling should be carried out in balance.

During the operation of biological contact oxidation, it should be noted that the excessive growth and shedding of biofilm may occur when the DO is not properly controlled, so the sludge load should be controlled between 0.2 and 0.3kgBOD5/ kgLMSS.

The effluent quality of dosing treatment with shallow air floatation should meet the inlet water quality condition of biochemical design, so that the stability of dosing with air floatation is conducive to subsequent biochemical treatment.

Before the operation of small sewage treatment equipment, all facilities, pipelines and underwater equipment should be inspected, and all sundries should be cleaned up effectively to avoid the blockage of pipelines and equipment and the maintenance of underwater equipment after water connection, which may affect the smooth commissioning.

In the early stage of bacterial culture, a large number of white foam will appear in the aeration tank, which will accumulate on the channel plate of the biochemical tank. This problem is a normal phenomenon, which can be solved as long as the dissolved oxygen is well controlled and appropriate defoaming measures are taken.

At the later stage, it is found that the effluent of the secondary sedimentation tank contains flocculent biofilm, and the sludge at the bottom of the sedimentation tank is easily turned into lumped sludge. Therefore, the sludge at the bottom of the sedimentation tank should be discharged as soon as possible to reduce the residence time in the secondary sedimentation tank

2.There are two installation forms of small sewage treatment equipment. The first one is placed above the surface, and the second one is buried below the surface. The depth of burial is determined according to the local temperature change. Surface should be smooth and base depth should support press >5t/m2.

The equipment is installed under the surface, and the relative elevation between the foundation and the surface is the same as the height of the equipment. If the equipment is qualified, the sewage treatment equipment shall be filled with water to prevent the groundwater from floating the equipment. Fan and electrical control system shall be checked before starting. Regular maintenance shall be conducted to test fan and its air inlet, water pumps. Usually 5000h once maintenance.