Aerobic Treatment Unit

Aerobic Treatment Unit (ATU) is an activated sludge process with extended aeration. The ATU has a septic tank which uses to collect the wastewater. This type of treatment is mainly based on the use of air that is added to the waste water from the solids chamber. The introduction of air promotes the growth of aerobic organisms and breaks down approx. 66% of the organic solids in the wastewater into stable, inorganic organic solids. 

The use of air in the aerobic treatment unit is called ventilation. This ventilation provides enough time for dissolved oxygen, wastewater mixing and decomposition of organic solids so that organisms and bacteria can get into the sewage treatment plant. In the activation room, the wastewater is milk chocolate-colored. When the drain leaves the septic tank, it ends up in a quiet place where there is no mixing. 

In the clarifier, the solid separates from the wastewater again. These solid particles sit down on the bottom of the clarifier which are known as sludge. This sludge has dissolved O2 which activates the bacteria of the sludge. These activated bacteria are move back into the activated sludge chamber for further mixing. The sludge is mixed with the arriving sewage, and this combination of sewage and sludge is called a mixing liquor. This mixture starts to move back into the clarifier, the solids are separated and returned to the aeration chamber.

The water separated from the solids by the cleaning system leaves the sewage treatment plant and enters the pump room, the so-called wastewater. The water is then chlorinated and disposed of. Probably a sprinkler.

Types of aerobic treatment systems

The aerobic treatment unit has the following major types:

1) Fixed film systems

The fixed aerobic treatment unit uses a porous medium. The porous medium provides a bed to support the biomass membrane, which digests wastewater. Solid film system design varies extensively, but they divide into two main categories. The first category is a system in which the medium moves relative to the effluent, with the film alternately submerged and exposed to air. The second is a system that uses a static medium to alter the flow of sewage and take turns submerging and exposing the film. 

In case of both categories, the biomass has to be exposed to both the wastewater and the air for aerobic fermentation.

This film can be constructed of an appropriate porous material like peat moss or molded plastic. The simple system uses a solid medium and relies on intermittent gravity to bring the sewage stream into regular contact with air and sewage. At any point in time, almost 40% of the disk is submerged in water and the shaft rotates 1-2 revolutions per minute.

2) Retrofit or portable aerobic systems

Another increasingly common use of aerobic treatment unit is to repair a failed or ineffective anaerobic tank system by modifying an existing system with aerobic functions. This type of product is known as aerobic repair and is a biologically ineffective and ineffective anaerobic delivery by significantly reducing the biochemical oxygen demand of wastewater (BOD5) and total suspended solids (TSS). The purpose is to fix the system. The reduction in TSS and BOD5 reversed the growth of biological mats. In addition, the wastewater with a high proportion of dissolved oxygen and aerobic bacteria flows into the manifold section and digests the biological mat. 

Comparison to traditional septic systems

The aeration and disinfection levels are the main differences from traditional septic tank systems. In fact, the aerobic treatment unit can be used as secondary treatment for septic tank sewage. Disinfectant tablets such as electrical parts (air compressors) and mechanical parts (air diffusers) need to be replaced regularly. On the plus side, the quality of the sewage produced by the aerobic system is higher than that from septic tanks, so the leach site can be smaller than that of traditional septic tanks and the drain can be directed into an overly sensitive environment. to the environment … leaving the area of ​​the septic tank system.