Submerged ultrafiltration membrane application
Submerged membrane system has unique advantages in large and medium-sized waterworks,decided that it will be the direction of development of large low pressure membrane method system.Immersion type membrane assembly comprises a hollow fiber membrane, fixed in the vertical or horizontal frame is arranged in the frame at the top and bottom of the water collecting pipe through the liquid. Each water collecting pipe comprises a layer of sealing membrane wires of special resin,the membrane cavity is connected with a pipe to collect the product water, thus submerged membrane components only water production end a connection point. Several or dozens ofmembrane components through two hard rectangular tubes connect the water collecting pipe, at the same time they fixed position, forming a film box. Periodic backwashing and slow gentle airscrubbing can reduce membrane surface concentration polarization, the operation modecorresponding to the low rate of membrane fouling. A plurality of membrane tank parallel immersionconsists of a membrane column in the membrane tank, a plurality of film column parallel processingsystem composed of different processing scale film.
Different from the traditional pressure type membrane filtration, submerged membrane is used to run in the state of negative pressure is lower, the use of siphon or the pump suction negative pressure filtration mode of water from the outside to the inside, realize low transmembrane pressure(TMP), DC steady operation of moderate membrane flux of total content filtering, which makes thethe overall energy consumption cost is lower than the pressure type membrane filtration, generally between 0.03-0.06kW - h/m3,this is mainly as follows.
The membrane pressure evenly distributed along the length direction of the hollow fiber membrane no pressure losses in the inlet side of the membrane;
The pumping mode operation of the transmembrane pressure and the membrane flux exerted adefinite limit, make it keep control region in constant pressure filtration curve.
From the system design, submerged membrane can be directly immersed into the need to deal withthe water, and thus the system covers an area of very small. This also to the transformation of the existing treatment plant to provide the conditions, can be installed into existing clarifier membraneor filter or other pool, so submerged membrane system regardless of the newly built or builtprocessing plant upgrades are very ideal: that is the same area, water content increased 2-4 times,at the same time guarantee the high quality product water. The use of a few pump, fan and valve need submerged membrane process of columns, the water f, eeding pump, using a distribution channel water to, , , each proc, ess in the pool, reducing the head loss, so that the water flow by gravity flow form. Ordinary backwash device can also be used, which reduces the occupied area, reduces the complexity of the system, reducing the investment and cost.
During normal operation of production through the liquid membrane system (produced water), the raw water through a water inlet pipe and a water inlet control valve into the membrane tank.Membrane immersed in the membrane tank in the raw water through the liquid pump from the filmon the inner side of the negative pressure suction membrane water wall. All the membrane boxeach film column generated from liquid passes through the liquid pump to collect common through the liquid is pumped Straw, to all the membrane column shared through the liquid duct, and finally into the next process.
The water surface of solid matter accumulation in the film, will gradually increase thetransmembrane pressure (TMP) value. Solid material backwashing process can remove themembrane surface, so that the TMP is restored to its former a water production cycle TMP value.The majority of the backwashing is done every day, help keep TMP and prolong the cleaning period, reduce the average energy consumption. Backwashing process including through liquidmembrane, reverse through aeration scrub film removal of sediment, prevent their deposition on the membrane pool and discharging the liquid in the waste liquid pool or sewage pipe. During backwashing, the air enters the ultrafiltration membrane on the surface of the bottom of the box form turbulent flow ultrafiltration membrane, the outer surface of the bubble in thescrub and clean up the ultrafiltration membrane filaments, improve the processing efficiency of ultrafiltration membrane. Then, to the inlet injection membrane pool, began to produce water. Water production also need to periodically stop for chemical cleaning of the membrane, organic pollutionremoval by membrane fouling substances or. Restorative cleaning frequency according to the water quality and operating conditions of treatment plant and change.
When submerged membrane system is becoming more and more popular, it is necessary tounderstand the composition and operation of the system, and pay attention to the design of support system or equipment. Although the film system design is the key parameters associated with membranes, such as films, fibers, the number of species of membrane element configuration, fluxand performance. The real challenge of membrane system successfully is to design equipmentrequired for the running of the system, designed to ensure the integration, considering hydrauliccondition, system of the whole water treatment plant, site constraints, standardize the other conditions required, cost, operation, repair, the required system redundancy and film the successful operation of the system. Membrane system equipment comprises a pump, blower and compressor,responsible for the day-to-day operation, including filtration, backwashing, cleaning and complete testing process.
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The water plant membrane pool layout
The use of ultrafiltration membrane for treatment of drinking water has become more and more popular, mainly because of microbe and <,/SPAN>turbidity standards more stringent. The progress of technology, reduce cost, increase the expert consultants and the end-user of the ultrafiltration membrane ultrafiltration membrane familiarity will result in large water plant application. At the same time, based on the area, energy consumption, drug consumption, supporting universal equipment and parts number, system complexity and with the conventional process of the convergence, the service life of the membrane and product life cycle cost analysis, the immersed ultrafiltration membrane is the best choice for large water plant in low pressure membrane process.