Backwashing of multi-media filters mainly refers to the interception and adsorption of a certain amount of impurities and stains by the filter material layer after a certain period of use, which makes the water quality of the filters'effluent decrease. The main characteristics are: the water quality of the filters becomes worse after normal filtration, the pressure difference between the inlet and outlet pipelines increases, and the flow rate of a single filter decreases.

反沖洗的原理：水流逆向通過濾料層，使濾層膨脹、懸浮，借助水流的剪切力和顆粒的碰撞摩擦力清洗濾料層使濾層內(nèi)的污物脫離并隨反洗水排出。

The principle of backwashing is that water flows backward through the filter material layer, which expands and suspends the filter layer. The filter material layer is cleaned by shear force of water flow and collision friction force of particles, so that the dirt in the filter layer is separated and discharged with the backwashing water.

反沖洗的必要性

Necessity of backwashing

(1)在過濾過程中，原水中的懸浮物等被濾料層截留吸附并不斷地在濾料層中積累，于是濾層孔隙逐漸被污物堵塞，在濾層表面形成濾餅，過濾水頭損失不斷增加。當(dāng)達(dá)到某一限度時(shí)，濾料需進(jìn)行清洗，使濾層恢復(fù)工作性能，繼續(xù)工作。

(1) In the process of filtration, suspended substances in raw water are intercepted and adsorbed by the filter material layer and accumulated continuously in the filter material layer. As a result, the pore of the filter layer is gradually blocked by dirt, forming filter cake on the surface of the filter layer and increasing the loss of the filter head. When a certain limit is reached, the filter material needs to be cleaned to restore the performance of the filter layer and continue to work.

(2)過濾時(shí)由于水頭損失增加，水流對(duì)吸附在濾料表面的污物的剪切力變大，其中有些顆粒在水流的沖擊下移到下層濾料中去，終會(huì)使水中的懸浮物含量不斷上升，水質(zhì)變差，當(dāng)雜質(zhì)透過濾層時(shí)，過濾器失去過濾效果。因此，到一定程度時(shí)，需要清洗濾料，以便恢復(fù)濾料層的納污能力。

(2) As the head loss increases, the shear force of water flow on the filtrate surface becomes larger. Some of the particles move to the lower filter media under the impact of water flow, which will eventually cause the suspended matter content in the water to rise continuously and the water quality to deteriorate. When impurities pass through the filter layer, the filter loses its filtering effect. Therefore, to a certain extent, it is necessary to clean the filter material in order to restore the ability of the filter material layer to absorb contamination.

(3)污水中的懸浮物中含有大量有機(jī)物，長(zhǎng)期滯留在濾層中會(huì)導(dǎo)致濾層中細(xì)菌微生物富集繁殖，發(fā)生厭氧腐敗現(xiàn)象，需定期清洗濾料。

(3) Suspended matter in sewage contains a large amount of organic matter. Long-term retention in the filter layer will lead to bacterial and microbial enrichment and reproduction in the filter layer, which will lead to anaerobic corruption. It is necessary to wash the filter material regularly.

反沖洗參數(shù)控制和確定

Control and determination of backwashing parameters

(1)膨脹高度：反沖洗時(shí)，為了保證濾料顆粒有足夠的間隙使污物迅速隨水排出濾層，濾層膨脹率應(yīng)大一些。但膨脹率過大時(shí)，單位體積中濾料的顆粒數(shù)變少，顆粒碰撞的機(jī)會(huì)也減少，所以對(duì)清洗不利。雙層濾料，膨脹率為40％----50％ 。

(1) Expansion height: When backwashing, in order to ensure that there is enough clearance between the filter particles so that the filtrate can be discharged quickly with water, the expansion rate of the filter should be larger. However, when the expansion rate is too large, the number of particles per unit volume of filter material decreases, and the chance of particle collision decreases, so it is not conducive to cleaning. The expansion rate of double-layer filter material is 40%-50%.

注意：在生產(chǎn)運(yùn)行中，對(duì)濾料的填充高度、膨脹高度等隨機(jī)進(jìn)行檢查，因?yàn)檎７聪催^程中，會(huì)有部分濾料的跑失或磨損，需要進(jìn)行補(bǔ)充。相對(duì)穩(wěn)定的濾層，有以下優(yōu)點(diǎn)：確保過濾水質(zhì)的穩(wěn)定，保證反沖洗的效果。

Note: In the production and operation, the filling height and expansion height of the filter material are inspected randomly, because in the normal backwashing process, some of the filter material will run away or wear, and need to be supplemented. The relatively stable filter layer has the following advantages: ensuring the stability of the water quality of the filter and ensuring the effect of backwashing.

(2)反洗水量和壓力：一般設(shè)計(jì)要求，反洗水的強(qiáng)度為40 m3／(m2?h)，反洗水的壓力≤0．15 MPa。

(2) Backwash water quantity and pressure: General design requirements, the strength of backwash water is 40 m3/(m2?H), and the pressure of backwash water is less than 0.15 MPa.

(3)反洗空氣量和壓力：反洗空氣的強(qiáng)度為15 m ／(m/h)，反洗空氣的壓力≤0．15 MPa。

(3) Air volume and pressure of backwashing: the strength of backwashing air is 15 m/(m/h), and the pressure of backwashing air is less than 0.15 MPa.

注意：在反洗過程中，通入的反洗空氣匯集于過濾器的頂部，大部分應(yīng)通過雙孔排氣閥排出。日常生產(chǎn)中。需經(jīng)常檢查排氣閥的通暢性，主要表征在閥球升降的自由度上。

Note: In the process of backwashing, the backwashing air is collected at the top of the filter, most of which should be discharged through the double-hole exhaust valve. Daily production. It is necessary to check the patency of exhaust valve frequently, which is mainly characterized by the degree of freedom of ball lifting.

好了，今天的精彩內(nèi)容就給大家介紹到這里了，如果大家還有疑問歡迎咨詢山東多介質(zhì)過濾器的官網(wǎng)客服人員：http://m.tiaoi.com.cn

Well, today's wonderful content is introduced here. If you have any questions, please consult the official website customer service staff of Shandong Multimedia Filter: http://m.tiaoi.com.cn.