One type is called the Activated Sludge Process, the other is known as the Biofilm Process. Wastewater treatment equipment for domestic wastewater is used to treat domestic wastewater. The Activated Sludge Process utilizes the biochemical metabolism of a suspended biomass community to aerobically treat wastewater and handle various forms. Integrated wastewater treatment equipment is used for industrial wastewater or rural domestic wastewater treatment. During the growth, reproduction, and development of microorganisms, we can form flocs with a large surface area, which can produce a large amount of flocculation and adsorption of colloidal or dissolved pollutants in wastewater. These substances are absorbed into the cell bodies, and with the participation of oxygen, these substances are completely oxidized to release energy, CO2, and H2O. The污泥 concentration level in the Activated Sludge Process is generally around 4g/L.

In the biological membrane process of wastewater treatment, microorganisms adhere to the surface of the media to form a colloidal-connected biofilm. The biofilm flocs are fluffy, with numerous micropores and a large surface area, which enhances their adsorption capacity, facilitating the decomposition and utilization of the adsorbed organic matter by the microorganisms. During the treatment process, the flow of water and the aeration continuously expose the biofilm surface to water, allowing the biofilm to absorb organic pollutants and dissolved oxygen from the wastewater. The microorganisms on the biofilm continuously decompose these organic substances, and as the organic matter is oxidized and decomposed, the biofilm itself is also metabolically active. Aging biofilm flakes off, and the treated water is then removed from the biological treatment facility, separating from the water in the sedimentation pond. The average sludge concentration in the biofilm process is 6 to 8 g/L.

To enhance sludge concentration and treatment efficiency, the activated sludge process can be combined with the biofilm process by adding media to the activated sludge tank. This bioreactor, which contains both attached biofilm microorganisms and suspended microorganisms, is known as a composite bioreactor. It boasts a high sludge concentration, typically around 14 g/L.