浸没式膜系统在大、中型自来水水厂的优势，决定了它将是大型低压膜法系统的发展方向。浸没式膜组件包括固定在垂直或水平框架上的中空纤维膜、设在框架顶部和底部的透过液集水管。每个集水管包含有一层密封膜丝的专用树脂，使得膜的内腔与管道相连以收集产品水，因此浸没式膜组件只有产水端一个连接点。几个或几十个膜组件通过两个硬直角管将其集水管相连接，同时将它们位置固定，形成一个膜箱。周期性反冲洗和平缓温和的空气擦洗可以减少膜面的浓差极化，这种运行方式对应于低的膜污染速率。若干个膜箱并联浸没在膜池中组成一个膜列，若干个膜列并联组成不同处理规模的膜处理系统。
与传统的压力式膜过滤不同，浸没式膜是在较低的负压状态下运行使用，利用虹吸或泵抽吸方式将水由外向内进行负压抽滤，实现低跨膜压差(TMP)、适度膜通量的平稳运行的直流式全量过滤，这使得其整体能耗成本低于压力式膜过滤，一般在0.03-0.06kW•h/m3之间。这主要表现为：
① 膜压差沿中空纤维膜长度方向均匀分布，在膜的进水一侧没有压降损失；
② 抽吸模式的运行对膜压差和膜通量施加了一个明确的限制，使其保持在过滤曲线的恒压控制区。
浸没式膜操作原理
从系统设计上，浸没式膜可被直接浸入到需要处理的水中，因此系统的占地面积非常小。这也就给现有处理厂的改造提供了条件，可以将膜安装到现有的澄清池或滤池或其它水池中，所以浸没式膜系统无论对新建还是已建处理厂的升级都非常理想：即同样的占地面积下，出水水量提高2-4倍，同时保证优质的产品水。使用成列的浸没式膜流程中需要很少的泵、风机和阀门，在进水泵处，使用配水渠将水输送到各个流程池中，减少了水头损失，使水以重力流形式流动。普通的反冲洗设备也可以使用，这减少了占地面积，降低了系统的复杂性，减少了投资和费用。
浸没式
在正常运行过程中膜系统生产透过液（产水），原水通过进水管和进水控制阀进入膜池。膜浸没在膜池中的原水中，透过液泵从膜内侧将水负压抽吸过膜壁。每个膜列的所有膜箱产生的透过液通过透过液泵收集到共用的透过液抽吸管后，再到所有膜列共用的透过液母管中，最后进入下一步的处理
进水中固体物质积累在膜的表面，会逐渐增加跨膜压差（TMP）值。反洗过程可以去除膜表面的固体物质，从而使TMP恢复到前一个产水周期中TMP值。多数反洗是每天进行的，有助于保持TMP且延长清洗周期，降低平均能耗。反洗过程包括将透过液反向透过膜、曝气擦洗膜去除沉积物，防止它们沉积在膜表面，并且将膜池中的液体排到废液池或污水管。在反冲洗时，空气进入了超滤膜箱的底部在超滤膜的表面形成紊流，上升中的气泡擦洗并清洁超滤膜丝的外表面，提高超滤膜的处理效率。然后，重新将进水注入膜池，开始产水。产水还需周期性地停止以对膜进行化学清洗，以去除膜的有机污染或是结垢物质。恢复性清洗的频率根据处理厂的水质和运行条件而变化。
当浸没式膜系统越来越普及，很有必要了解该系统的组成和运行，并注意支持系统或配套设备的设计。尽管膜系统设计的重点是与膜有关的参数，比如膜的种类、纤维数、膜元件配置、通量和性能等。成功的膜系统的真正挑战是系统运行所需配套设备的设计,保证一体的设计，考虑系统水力条件、整个水处理厂、现场约束条件、规范要求、成本、运行、维修、系统冗余以及膜系统成功运行所需的其它条件。膜系统配套设备包括泵、鼓风机和空压机等，负责日常运行，包括过滤、反洗、清洗和完整性测试等工艺过程。
自来水厂膜池平面布置
使用超滤膜处理饮用水已经越来越普遍，主要是因为有关微生物和浊度的标准越来越严格。技术的进步、成本的降低、增加的专家顾问和终端用户对超滤膜的熟悉程度将会导致超滤膜在大型自来水厂中的应用。同时，基于占地面积、能耗、药耗、配套通用设备与配件数量、系统复杂性及与常规工艺的衔接性、膜使用寿命和产品生命周期成本等综合分析，浸没式超滤膜将是大型自来水厂低压膜法工艺的选择。
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.
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