BackgroundWaste water treatment is an essential process. It is important for waste discharge and water reuse in industry as well as being a necessity in suburban settings. While there are different processes which are used for waste water treatment, two of these processes are the conventional process and the membrane bioreactor process (MBR). The conventional process uses the action of microorganisms to the breakdown chemical components of effluent systems.
Unfortunately, the conventional process cannot keep up with the demands of the rising population. Therefore, the MBR has gained popularity. The MBR was developed 40 years ago, and has been used commercially for almost 30 years in Japan. Apart for muncipal and industrial purposes, the MBR is also for (1)Filtration (2) Ultrafiltration (3) Microfiltration (4) Removal of salts (5) Reverse Osmosis (6) Nanofiltration (7) Irrigation. This process uses membrane coupled aerobic bioreactors and an activated sludged system with an integrated membrane, therby eliminating the need for a final clarifier. There is also something known as membrane fouling which in other words is the membrane performance. This performance is dependent on the effluent quality of the biofilm reactor and it varies with the hydraulic retention time (it's the time the wastewater takes to pass through the system). Due to the increase in population, MBR must be used. Apart from this there are several other advantages MBR has over the conventional process.
Some advantages of MBR are :
- Reduction of importance of biomass sedimentation, thus allowing a significantly smaller tank compared to conventional process.
- The biosolids which are to be treated are low dense solids, theirs rate of settlement would be slow. Thus a larger tank (more space) js required in the conventional process.
- Consistently high effluent quality, and operational separation of solids retention time( it is the average time for the activated sludge solids to be in the system. This is usually expressed in days) and hydraulic retention time. While there are advantages too, there are disadvantages as well.
- The membrane fouling uses aeration since fouling is best achieved by large bubbles. Thus it uses a lot of energy for aeration and compared to conventional treatment.
Technical ProjectBiofilms are adherent aggregates of microorganisms that develop on surfaces. They can be found in a multitude of natural circumstances (for example, the bottom of streams, inside of plants, and on teeth) and can be utilized for tasks such as water treatment. In water treatment, water is run over the biofilm, and microorganisms absorb and digest undesirable compounds. The force of the water can cause part of the biofilm to break off and become a sludge that must later be removed.
A silica barrier on the exterior of the biofilm would help to prevent sludge while still allowing the biofilm to function. Furthermore, a silica coat would act as a mechanical filter to remove any large particles from the water. In order for this silica coat to form, silica binding protein (SBP) needs to be expressed on the surface of the microorganisms. Our objective is to develop a device in Escherichia coli that will induce the expression of adhesion proteins to facilitate biofilm formation and will induce the production of SBP after a biofilm has formed.