Toolkit

1. What is RBC?

The rotating biological contactor (RBC) is a biological equipment used in the treatment of sewage. The RBC allows the sewage to contact with biological medium in order to remove pollutants before discharging to the environment. A RBC is a type of secondary treatment process containing a series of closely spaced, parallel discs. Microorganisms can grow on the surface of the discs and degrade the pollutants in the sewage.

2. Why is RBC?

Sewage, containing a complex of heavy metal ions, contaminants of organics and other pollutants, will ferment and become the source of diseases if untreated. With the development of industrialization in China, there are more and more sewage produced, which generate a rising concern among the public.
RBC，an advanced sewage treatment technology, now is widely used to remove soluble, biodegradable, organic materials from industrial sewage and domestic one, making it safe for further use. Compared with traditional method, such as sedimentation and filterability of sludge, it has the benefits of effectively overcoming the limitations associated with poor settling of the sludge and secondary chemical contamination.

3. The designing of our equipment

Since our project has some special requirement for this water dealing toolkit, we should reform some features of the traditional RBC to make it meet our needs. We changed the shape of it stimulated by the idea of continuous setting vessels, making it’s easier for collecting the gene modified bacteria-E. worker. We also added a small drawer on the side of water outlet to let another gene modified bacteria-E. instructor grow and direct when this sewage is well dealt and safe for further use. Here are some 3D structure designing diagrams from different angles of our toolkit:

We planned to attach our gene modified bacteria complex-E. kungfu-to the rotating disks with culture media. The rotating process can be divided into two parts: above the water and under the water. When the E. kungfu is exposed to the air, it will consume the oxygen to grow and produce proteins which we need. While it is under the water, the copper binding protein will be able to play its role to surface displaying copper ions and remove them from the sewage. The sewage will come in through the entrance, and then stay in the box for several hours for the reaction. To ensure that the bacteria will have enough time stay under the water to play their roles, the rotating speed should be about 1.5~3 rpm. After that the water will come into the secondary sedimentation tank, then the third one and so on, until our instructors indicate that the water is safe in the amount of copper ions.
During the whole dealing process, the bacteria will grow and aggregate by using BOD (Biochemical Oxygen Demand) in the sewage, and become heavier and heavier. When they become heavy enough, they will fall down from the rotating disks due to the gravity and shearing forces caused by the contact with water. After being washed into the bottom of the tank, we can collect all these bacteria in the form of sludge. In the other hand, when we want to collect the bacterial but it is not heavy enough to deposit, we can use ultraviolet to promote the kill switch in E. kungfu. Then effluent and copper recycling can be taken into consideration.