Applications: Municipal Sewerage
With over 549 operational municipal sewage plants utilizing the Kubota flat sheet submerged membrane process around the world, MBR Wastewater Treatment Ltd. is expertly placed to assist with your requirements.
Moneyreagh, Northern Ireland
Picnic Bay, Australia
The development of MBR Wastewater Treatment’s submerged membrane bioreactor technology was the result of a Japanese Government initiative to produce compact high quality effluent treatment plants. Since producing the first pilot plant using this technology in 1989, and the first commercial plant in 1991, over 900 plants have been installed worldwide. These treat a wide range of effluents, the principal application being sewage and sludge liquors, but also including industrial wastewater, manufacturing and processing wastewater, and graywater recycling for a wide range of re-use purposes. In the UK, a pilot trial has been run at Kingston Seymour WwTW since 1995. A full-scale plant has been operating successfully at Porlock WwTW since February 1998, treating a population waste of approximately 3,800 persons. Swanage WwTW has been operating since September 2000 treating a population waste of approximately 28,000 persons.
The process employs simple flat sheet membrane panels housed in GRP units and aerated by a coarse bubble system below each unit. A series of these membranes are submerged within an activated sludge treatment tank. The aeration necessary for treatment of the liquors also generates an upward cross-flow over the membranes; this is essential to keep fouling of the filtration surface to a minimum. An advantage of this design is that the membrane panels are securely retained and do not touch or abrade each other, while the units also act as a flume to ensure effective tank mixing and even distribution of the biomass.
The membrane panels are manufactured with a pore size in the range of 0.1 to 0.4 microns which in operation becomes covered by a dynamic layer of protein and cellular material. This further enhances the effectiveness of this filtration performance by providing an effective pore size of less than 0.01 microns, which is in the ultra-filtration range.
Our membrane bioreactor treatment produces a high quality disinfected effluent. The raw sewage generally only requires screening and de-gritting prior to entering the membrane bioreactor tank. The process requires no primary or secondary settlement stages and no additional tertiary treatment or UV stages to achieve this very high disinfection quality typically better than 5:5:5 BOD:Suspended Solids:Ammonia.
MBR Wastewater Treatment Ltd.’s Membrane Bioreactor Technology has a number of inherent advantages. The system does not require flocs to be formed to remove the solids by settlement and therefore the biomass can operate at very high levels of MLSS, generally in the order of 12,000-18,000 mg/l, and as high as 22,000 mg/l. This high concentration enables a low tank volume and a long sludge age to be utilized, which substantially reduces sludge production.
The hydraulic flow determines the required number of membrane units. Each membrane unit may contain up to 200 flat sheet membrane panels housed within a rectangular box, together with an integral aeration system in the bottom section of the unit. Treated effluent is removed from the membrane units using gravity head (typically 1 – 1.2 m), or a pumped suction operation can be utilized.
Operation and Maintenance
Operating experience of the pilot and main treatment plants has consistently shown an effluent of high quality, that has little dependence on variations in feed strength and is fully disinfected with bacteria and viruses reduced to below the EU limits for swimming water or recreational water standards.
By minimizing the effect of fouling through controlled cross flow velocities over the membrane surface cleaning is required typically only twice per year using a backwash of high dilution dilute sodium hypochlorite solution into each membrane unit.
The process is designed to run without supervision and by using high quality plastics and stainless steel, the membrane panels and units have long life expectancies in the most part beyond 10 years.
Characteristics of the available wastewater treatment technologies
Ease of operation
No odor/vector attraction
High biomass concentration
High loading rates
Tolerates shock loading
High & consistent effluent quality
Disinfection without UV/chemicals
Effluent suitable for agricultural or graywater reuse
Effluent suitable for discharge to sensitive waters