In the commercial and Hospitality industry certain industry experts typically propose the MBBR process. Further explanation below will make this easier understood:
MBR technology is an advanced technology utilizing membranes instead of clarifiers. Initially this started as a filtration system external to the biological treatment process. At times clarifiers were even used followed by membrane filtration systems. Eventually this developed into an integrated system. The biological process occurs as it is typically accomplished in effluent treatment with a small exception of being able to keep the bacterial concentration used for treatment about twice as high. The blower size, or air requirements, for the biological portion of an MBBR is about the same as in other biological processes. This is based solely on BOD of the influent water. Following the biological system, there is a Membrane operating system. This is either designed in a submerged Tank fashion or as external Pressurized filtration systems. Both the submerged and the Pressurized systems are frequently flushed with a large amount of air to help clear the membrane from the high level of biological fouling caused by the bacterial filtration. This aeration adds a substantial amount of energy and has been some of the primary focuses of large MBR supplier Research and development. Sooner or later, depending upon the influent water, the entire system will have to be taken off line and sent through a chemical cleaning/backwash, requiring chemical storage and handling onsite. Upon cleaning, the system is put back into operation. Fouling may or may not get cleaned off and is called irreversible fouling which simply means cannot be cleaned and is a normal part of the membrane degradation leading to the end of its functional life. Suppliers account for this by over sizing so that as the fouling occurs it will still meet volumetric requirements for awhile. Eventually over time the membrane will need to be replaced. Understand that from the minute it is put into operation its life time is limited. This depends upon the membrane manufacturer, feed stream and operational technical capabilities.
MBR’s suffer from several challenges:
- Membranes are subject to fouling by oil and grease. If there is an operational failure of pre-treatment, membranes can be irreversibly fouled. This means that if someone fails to get Oil and Grease trapped cleaned, membranes could be permanently damaged. If a Kitchen crew accidently dumps too much oil or grease down the drain, the system could be damaged. If other chemicals or surfactants are added, membranes can be damage.
- Membranes are susceptible to abrasive damage caused by fine sand and silt, typically smaller particles than what pre-treatment removes. This is a large problem and includes major suppliers such as G.E. and Evoqua where many modules have had to be replaced.
- Membranes will lose filtration capability due to cleaning chemicals and irreversible fouling. This is inevitable. The begin their life cycle the moment they are turned on. I have seen failures to the point of making the system unusable in the matter of 6 months. When this happens, the modules must be replaced and typically you are locked into the suppliers modules as the system has been designed for specific module as there is no standard in the industry. Large Companies are rumored to sell low to get the sale and earn a much higher mark-up on the replacements because the customer simply has no choice.
- MBR’s typically have higher energy requirements then other biological treatment systems. They both use about the same amount of energy for the aeration of the biological process, but the MBR has a further requirement of membrane aeration to keep the cake fouling of the membranes from building up too fast. In many cases, this energy for aeration can exceed the actual energy of the biological treatment system. It puts a large load on back-up generators as well.
Typically the commercial and hospitality industry is an industry with many fluctuations. Large events and full resorts followed by slower time periods. The treatment of the portion of the effluent waters associated with human waste is straight forward based on number of people. Human sewage is predictable to the point of understanding even the times of peak flows and minimal flows. The portion of the waste water that comes from restaurants, Cleaning, vehicles, laundry and other “Industrial related water” generations is much more variable. While the biological system in both MBR and MBBR may be able to be designed for all of the possible failure modes of human workers, kitchen staff, boiler cleanouts etc, the pre-treatment systems often cannot. MBR has found great applications in small, medium to large municipal treatment systems that are focused on reclaiming the water back to drinking water standards. A classic example is The Singapore PUB “NEWATER” process where after filtration, the water goes through a Reverse Osmosis unit followed by disinfection and distribution. With that said, MBR’s require absolute controlled environment from the influent pre-treatment through the biological process to the membrane filtration system. Each and every unit process must operate as designed or risk damage to the membrane system of the MBR. It typically requires a higher level of operator training including University degrees. A thorough understanding of the process, water treatment processes in general and the specifics of the influent are required. Anything less than this could cause severe damage to the membranes to the point of requiring replacement. MBR’s we have seen and actually modified in the commercial.
Moving bed biofilm reactor (MBBR)
Mbbr’s are also biological treatment systems with the bacteria attached to a high surface area Plastic carrier that moves around the treatment tank, ergo the name Moving Bed Bio Reactor. They have the ability to deal with high peaks better than other conventional biological treatment systems. They can also produce a high quality effluent. We recommend these in commercial and hospitality industries because in applications where highly technical operators are unavailable and large variations can occur these systems are far more recoverable. If a large amount of oil or grease was introduce, it could affect the biological system but can simply be pushed through or cleaned using absorbent materials and the system can go back on line. NO PERMANENT DAMAGE. The plastic media last 5-7 years and is inexpensive to replace. MBBR’s also use lower energy than MBR’s so if the treated water is going to just be discharged instead of reused, it reduces the overall operating costs. With and MBR you would be paying for both the membranes and more importantly the membrane aeration energy. This does have value if you going to recover the water only to drinking water standards. For recycle for landscaping, simple chlorination after MBBR treatment provides water suitable for landscaping purposes with the high cost of energy and membranes.
From http://www.noberu.com/
Membrane Solutions, LLC
(Cell)0086-15172323686
(Skype)roy.wong66
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