The media also acts as biological filter that filters organic matter. In attached growth systems the biomass is not in a constant state of suspension but is attached to the media. Attached Growth systems are therefore a more robust system in their ability to handle a temporary increase in the volume and concentration of incoming sewage due to the filtering effect of the media. Surges of sewage are buffered by the presence of the media by slowing the flow and allowing for the attached microorganisms to digest the sewage.
The benefits of attached growth are typically a smaller footprint and higher level of treatment. Sludge biosolids build up for removal and disposal will vary dependent on the specific attached growth technology selected. The most common suspended growth process used for municipal wastewater treatment is the activated sludge process. The process involves air or oxygen being introduced into a mixture of screened, and primary treated sewage or industrial wastewater combined with organisms to develop a biological floc which reduces the organic content of the sewage.
This material, which in healthy sludge is a brown floc, is largely composed of saprotrophic bacteria but also has an important protozoan flora mainly composed of amoebae, Spirotrichs, Peritrichs including Vorticellids and a range of other filter feeding species. The combination of wastewater and biological mass is commonly known as mixed liquor.
In all activated sludge plants, once the wastewater has received sufficient treatment, excess mixed liquor is discharged into settling tanks and the treated supernatant is run off to undergo further treatment before discharge.
Part of the settled material, the sludge, is returned to the head of the aeration system to re- seed the new wastewater entering the tank. This fraction of the floc is called return activated sludge R.
Excess sludge is called surplus activated sludge S. S is removed from the treatment process to keep the ratio of biomass to food supplied in the wastewater in balance, and is further treated by digestion, either under anaerobic or aerobic conditions prior to disposal. Many sewage treatment plants use axial flow pumps to transfer nitrified mixed liquor from the aeration zone to the anoxic zone for denitrification.
These pumps are often referred to as internal mixed liquor recycle pumps IMLR pumps. The raw sewage, the RAS, and the nitrified mixed liquor are mixed by submersible mixers in the anoxic zones in order to achieve denitrification. Diffused aeration is of course needed. The UASB reactor is a methanogenic methane-producing digester that evolved from the anaerobic clarigester. UASB uses an anaerobic process whilst forming a blanket of granular sludge which suspends in the tank.
Wastewater flows upwards through the blanket and is processed degraded by the anaerobic microorganisms. The upward flow combined with the settling action of gravity suspends the blanket with the aid of flocculants.
The blanket begins to reach maturity at around 3 months. Small sludge granules begin to form whose surface area is covered in aggregations of bacteria. In the absence of any support matrix, the flow conditions create a selective environment in which only those microorganisms, capable of attaching to each other, survive and proliferate.
Eventually the aggregates form into dense compact biofilms referred to as "granules". Biogas with a high concentration of methane is produced as a by-product, and this may be captured and used as an energy source, to generate electricity for export and to cover its own running power. The technology needs constant monitoring when put into use to ensure that the sludge blanket is maintained, and not washed out thereby losing the effect.
The heat produced as a by-product of electricity generation can be reused to heat the digestion tanks. The media used are small particle size sand, activated carbon, etc. Under fluidized state, each media provides a large surface area for biofilm formation and growth. It enables the attainment of high reactor biomass hold-up and promotes system efficiency and stability. This provides an opportunity for higher organic loading rates and greater resistance to inhibitors.
Fluidized bed technology is more effective than anaerobic filter technology as it favors the transport of microbial cells from the bulk to the surface and thus enhances the contact between the microorganisms and the substrate. Finally, the capital cost is lower due to reduced reactor volumes. However, the recycling of effluent may be necessary to achieve bed expansion as in the case of expanded bed reactor. In the expanded bed design, microorganisms are attached to an inert support medium such as sand, gravel or plastics as in fluidized bed reactor.
However, the diameter of the particles is slightly bigger as compared to that used in fluidized beds. The principle used for the expansion is also similar to that for the fluidized bed, i. Advantages of Anaerobic fluidized bed reactor The fluidized bed process claims various potential advantages over other high rate anaerobic reactors such as upflow anaerobic sludge blanket UASB reactors, filter reactors and downflow stationary fixed film reactor DSFF.
These are high sludge activity, high treatment efficiency, no clogging of reactors, no problems of sludge retention, least chance of organic shock loads and gas hold up as well as small area requirements. Materials and Methods From the above four types of bioreactors, the Anaerobic Fluidized Bioreactor type is not used in anywhere in India.
The remaining three types are largely used. For this study purpose, three different STPs are considered. TOC in the effluent was lower than 2. Chu et. Source: Chu et. An important advantage of MBBR is that less volume is required for treating the wastewater. Kermani et al. Source: Kermani et. The efficiency of the reactor has been demonstrated in many process combinations, both for BOD-removal and nutrient removal.
The advantage over other biofilm processes is its flexibility and a further study on this bioreactor can yield more results. Nitrogen removal using biodegradable polymers as carbon source and biofilm carriers in a moving bed biofilm reactor. Chemical Engineering Journal, 1 , — Related Papers. By Anjali Ramwani. Simultaneous nitrogen and carbon removal from wastewater at different operating conditions in a moving bed biofilm reactor MBBR : Process modeling and optimization.
By Ali Akbar Zinatizadeh. Review on Biofilm Processes for Wastewater Treatment. MBBR which is commonly known as moving bed biofilm reactor is a modern water treatment technology and process. It was first invented in the late in the s by professor Hallvard of Norwegian University of science and technology. Unlike most traditional water wastage treatment systems, MBBR is a highly effective biological water treatment process which is based on a combination of biofilm media and conventional activated sludge processes.
This way, water can be treated in both anaerobic and aerobic environments. MBBR is currently the best water treatment solution for high-strength water systems. This is mainly because of the biological nitrogen removal BNR , which uses MBBR systems thus improving waste matter quality and increasing treatment capacity with no extra footprint growth.
This process is widely used for industrial and municipal wastewater treatment process. Unlike the polishing process, the MBR is used as a tertiary water treatment step that has no return of active biomass to the biological process. Currently, most MBR processes in commercial places today make use of the membrane as a filter to which rejects all solid materials developed in the natural process.
MBR also uses low-pressure microfiltration and ultrafiltration in the process of wastewater treatment. The membrane used in the process also helps ensure that there are no gravity settling solids after the process which is the case conventional clarifiers. The MBR level of filtration allows high-quality effluent through the membrane thus eliminating the sedimentation. This explains why filtration is a critical process during the MBR. The MBBR technology also has enhanced processing stability not to mention high suspended biomass operation.
This will help ensure perfection and accuracy of the wastewater treatment process by using the MBBR technology. For you to get the best out of the MBBR process, using the best model is paramount. However, with the right procedure to follow, you do not need an expert to help you in the design process of the MBBR.
The first step when it comes to MBBR design should understand the discharge charges in your state. This is especially when you are designing the MBBR water treatment plant to meet the regulatory norm. Additionally, in case you intend to reuse the water after waste treatment, you need to familiarize yourself with the standards required for one to re-use treated sewage water.
For instance, for chores such as irrigation, you may not expect high standard is reusing. In case you need a water treatment plant to help prevent lousy smell and do not intend to reuse the water, then a central water treatment plant would be enough. However, you also need to follow the right standards in this one too to ensure that you get the get the best results from your investment. Different plants will have different design calculations since sewage characteristics differ depending on the source of the sewage.
This means that you need to consider several factors to ensure that you make the right design calculations. These include:.
These MBBR functions will help you calculate the best tank volume for the process, and air or oxygen requirement for there to be a coarse bubble aerations system. However, this should all be based on carrier characteristics, aeration system characteristics, and wastewater characteristics.
Ideally, the MBBR process is known to improve reliability, simplify the operation and process not to mention the fact that it requires a smaller storage space compared to traditional sewage treatment plants. For this reason, there is a well-managed technology behind the MBBR process to help ensure this become possible. The technology involved during the MBBR process uses thousands of polyethylene biofilm carriers.
These carriers operate within an aerated mixed wastewater treatment basin in a combined motion. Each carrier provides a protected carrier which helps in the help in the growth of autotrophic and heterotrophic bacteria within the cells. This technology helps increase productivity and effectiveness of the process.
The high population of bacteria helps achieve high rate biodegradation within the system and also provide ease of operation, not to mention the reliability of the process. The MBBR process also has an optimum level of productive biofilm which makes the process and the technology cost-effective and easy to maintain. There is also the biofilm which is attached to the mobile carriers found within the system which automatically respond to load fluctuations.
Like in any other situation, the MBBR technology has both its bright sides and the dark sides too. For instance, one of the most significant advantages of MBBR technology is that it can be used in already existing tanks. This means that you do not need new tanks when you intend to plan to introduce the MBBR process in your home or institution.
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