RBC（Biological Turntable）

1. Three-dimensional biological rotating disc (3D--RBC)

The three-dimensional biological rotating disc (RBC) is a biofilm wastewater treatment technology. It is an efficient and economical sewage biological treatment equipment developed on the basis of a biological filter. It consists of a water tank and a rotating disc body partially immersed in sewage. The microbial film growing on the surface of the disc body repeatedly contacts the sewage in the tank and the oxygen in the air, so that the sewage is purified.

2. Performance characteristics

In terms of structural design

The disc body is modularly designed, without clogging and not easy to damage. Its unique fan-shaped design makes replacement and maintenance very convenient and easy. Moreover, the disc is light, corrosion-resistant, and easy to form a film.

The tank body is designed to be a semicircle that matches the shape of the disc, so that the water flow has no short-circuit phenomenon and no deposition.

In terms of treatment capacity

The membrane is thick, the food chain of microorganisms is long and the concentration is high, the treatment capacity per unit volume of the disc is high, and the effect is good.

In terms of operation and operation

Axial water inlet, single-axis multi-stage combined transmission, energy saving, and simple tank body. And it adopts automatic monitoring, which can adapt to the changes in water quality and quantity by adjusting the speed, and the water quality is guaranteed1.

It has strong adaptability to changes in sewage quality and quantity, does not require special technology, is easy to maintain and manage, and has low operating costs.

3. Structure and working principle

Structural composition

Disc: It is the main body of the biological turntable. As a carrier of the biofilm, it has the characteristics of light weight, high strength, corrosion resistance, anti-aging, and large specific surface area. Foam plastic board, fiberglass, stainless steel, polyvinyl chloride or polystyrene are often used.

Contact oxidation tank: It is located directly below the turntable, with a rectangular plane shape and a semicircular cross-section. It is generally made of steel plate or reinforced concrete. Water inlet equipment is provided at both ends of the oxidation tank, and mud discharge pipes and vent pipes are provided at the bottom of the tank.

Rotating shaft: A solid steel shaft or seamless steel pipe is used, and the shaft length is controlled between 5-7m. The distance between the center of the shaft and the water surface is ≥0.15m to ensure that the shaft is above the liquid surface. According to the arrangement of the disc and the shaft, the turntable can be a single-axis single-stage type, a single-axis multi-stage type or a multi-axis multi-stage type.

Drive device: The drive device of the biological turntable includes two parts: a power device and a reduction device. The power device is divided into electric mechanical transmission, air transmission and hydraulic transmission, etc., and is generally driven by electricity. The electric biological turntable is powered by an electric motor, and the speed change device drives the shaft to rotate at the desired speed.

Working principle

During operation, when the disc contacts the sewage in the reaction tank, the biofilm attached to the disc fully contacts and adsorbs the organic matter in the sewage, and at the same time absorbs the dissolved oxygen in the water film outside the biofilm, decomposes the organic matter under the action of biological enzymes, and the microorganisms use the nutrients produced by the decomposition of organic matter to reproduce themselves and maintain the number of biofilms. When the disc leaves the sewage, a thin layer of water film is formed on the surface of the disc, and air continuously dissolves into the water film to increase the oxygen concentration of the water film. The biofilm alternately contacts the sewage and air, forming a continuous process of oxygen absorption, adsorption, oxidation and decomposition, and the purpose of water purification is achieved by continuously treating organic matter in this way. When the biofilm on the disc grows to a certain thickness, the microorganisms contacting the disc end will undergo anaerobic metabolism due to lack of oxygen, forming an anaerobic layer (anaerobic biofilm) inside. Due to the existence of the aerobic layer and the anaerobic layer, the effect of removing ammonia nitrogen is achieved. The gradually aged biofilm is constantly peeled off under the shear force generated when the turntable rotates and the flushing effect of the generated gas and aeration, in exchange for the growth of new biofilm, so that the biofilm has always maintained a high activity. At this time, the detached biofilm will flow out of the pool with the effluent and be removed by subsequent sedimentation equipment.

4. Scope of application

Remove BOD (biochemical oxygen demand), COD (chemical oxygen demand), NH3-N (ammonia nitrogen), SS and other indicators in sewage.

Suitable for biochemical treatment of small and medium-sized sewage treatment plants, including chemical fiber, petrochemical, mechanical processing, printing and dyeing, leather making, papermaking, coal gas, food, breeding, and biochemical treatment of landfill leachate.

River water body eutrophication treatment, municipal engineering water supply pre-biochemical treatment, new sewage treatment facilities, pre-treatment of existing sewage facilities (to enhance treatment capacity, etc.), post-treatment of existing sewage facilities (to stabilize water quality, etc.), BOD 20 - 2000mg/L (specially designed to meet water quality requirements below 10mg/L and above 10000mg/L) is mainly used for biochemical treatment of chemical fiber, petrochemical, mechanical processing, printing and dyeing, leather, papermaking, gas, food, breeding, and garbage leachate.

5. Comparison of technical advantages

Take 3D-RBC® biological turntable process as an example. Compared with the traditional AO process, the unit operating cost is reduced by about 0.4 (yuan/ton of water), the service life of the main equipment is extended by about 10 years, the land area is reduced by about 150m² (500t/d as an example), and the construction period is reduced by about 7 days (500t/d as an example); compared with the MBR process, the unit construction cost is reduced by about 3000 (yuan/ton of water), the unit operating cost is reduced by about 0.4 (yuan/ton of water), the service life of the main equipment is extended by about 25 years, the land area is reduced by about 150m² (500t/d as an example), and the construction period is reduced by about 7 days (500t/d as an example). It also has the advantages of low energy consumption, easy film hanging, impact resistance; small footprint, easy installation; less sludge, environmentally friendly; long life, easy maintenance, etc.

6. Application Cases and Commercial Applications

The domestic sewage treatment in various scenarios such as towns, hospitals, schools, scenic spots, service areas, etc. has a high market penetration, and the 3D-RBC® biological rotary disc equipment has a high degree of recognition in China and many countries such as Japan, the Philippines, and Mauritius. For example, taking a 50t/d rural sewage treatment project as an example, the use of the 3D-RBC® biological rotary disc process can meet the Class A standard of the Pollutant Discharge Standard for Urban Sewage Treatment Plants of the People's Republic of China (GB18918-2002), and can reduce COD: 300mg; BOD5: 150mg; SS: 190mg; TN: 25mg; NH3-H: 25mg; TP: 2.5mg per liter of water. By treating domestic sewage in villages and towns, the surrounding environment is beautified, the surrounding pollution is reduced, the quality of life of the people is improved, and the health of the body is protected; the surface water and groundwater pollution caused by sewage discharge is reduced, and it can be reused for flushing toilets, greening, landscaping, etc., bringing direct economic benefits.