Views: 8 Author: Site Editor Publish Time: 2020-06-19 Origin: Site
MBR, also known as membrane bioreactor, is a new water treatment technology which combines activated sludge process and membrane separation technology. There are four kinds of MBR membrane: hollow fiber membrane, flat membrane, ceramic membrane and tubular membrane.
Ceramic membrane is a new one in recent years. It is called "flat membrane" together with organic flat membrane. The chemical stability of ceramic membrane is very good. It can resist acid, alkali, organic solvent and high temperature. It has the advantages of narrow pore size distribution and high separation efficiency. The main materials of ceramic membrane are alumina, titanium oxide and silicon oxide.
Flat ceramic membrane module: the common one is a frame made of 304 stainless steel by welding. Ceramic membrane should be inserted into it for fixation, and install aeration pipe fittings and water collection pipe fittings and so on. At present, the common 10-250 pieces can form an integral component, regardless of the size of the single membrane.
In theory, after the diaphragm is damaged and the water production drops, the membrane module should be checked and replaced on a single chip, so as to save the cost of replacement.
About the installation of flat ceramic membrane, it is divided into dry membrane and wet membrane. Generally, membrane components and membrane supports are transported to the project site separately, and also they can be transported to the project site after assembly.
Normal condition: the membrane element shall be packed in a single sealed package, packed into wooden cases and transported to the site together with the support. NanoMem® will provide installation video and send professional installation personnel for guiding the installation.
How to clean ceramic membrane components？
The operating pressure of flat ceramic membrane is 0.1-0.3kpa. Under the action of self-priming pump (10 minutes for a working cycle, 8 minutes for pumping and 2 minutes for stopping), the mixed liquid passes through the microporous filter membrane in the membrane pool and uses its uniform pore diameter to intercept the particles and bacteria in the water, so that it can not be removed through the filter membrane. The sludge containing sewage is filtered to realize the sludge Water separation in the biochemical reaction pool. Therefore, the flat ceramic membrane plays the role of filtration.
1. The membrane intercepts the microorganism in the reaction tank, which greatly increases the concentration of activated sludge in the tank (the common concentration is about 6000-12000mg / L), and makes the biochemical reaction of degradation sewage more rapid and thorough;
2. Due to the high filtration precision of the ceramic membrane, the effluent is clear and transparent, and high quality water production is obtained. The ceramic membrane is not omnipotent. It has pore diameter. If impurities can't be filtered, it will form a fouling plug near the membrane hole. That is to say, the membrane is blocked, the water production is insufficient, and the flux can't be reached.
The cleaning of membrane module is mainly divided into online cleaning and offline cleaning.
Generally, online chemical cleaning method is used for cleaning, and the cleaning cycle depends on the membrane pollution. For better water quality such as domestic sewage, it may be cleaned once every 3 or 4 months, but for worse water quality such as landfill leachate, it shall be cleaned once every 15 or 20 days. For the preparation of solution, the common cleaning is to carry out acid washing after alkali washing according to the situation, and there will be acid washing before alkali washing.
Alkali washing is mainly a mixed aqueous solution of sodium hypochlorite and sodium hydroxide. Acid pickling is usually done with oxalic acid or citric acid. If there are many calcium ions, the oxalic acid shouldn’t be sued. This different manufacturer will give the corresponding parameters, which are basically 3-5L solution for each membrane, so it's good to add up the required amount. Dosing is divided into gravity flow or dosing pump.
The simple operation of cleaning:
When the membrane operation is slightly polluted, the method of online cleaning can be adopted, which is simple in operation; generally, alkali washing and acid pickling can be carried out first, and gravity flow or metering pump can be used for dosing.
Alkali washing: prepare 2000-5000mg / L sodium hypochlorite and 1000mg / L sodium hydroxide mixed aqueous solution, use the high-level cleaning water tank hydrostatic pressure to pour into the membrane element, the dosage of liquid medicine is 3-5l / tablet, and soak for more than 5 hours.
Acid pickling: prepare 1000mg / L oxalic acid (citric acid) solution, wash online with the same amount of water, and soak for 3-5 hours.
Note: the above reagents are calculated as per 100% purity. When the selected reagents contain impurities, calculate the corresponding dosage according to the corresponding purity. The method of gravity flow is used to inject the liquid medicine into the membrane through the dosing port, then clean the membrane.
The off-line cleaning is also called maintenance cleaning. Generally, the off-line cleaning is carried out when the membrane flux cannot be recovered after online cleaning in one year. Set up an off-line cleaning tank or membrane tank for cleaning. The whole tank is soaked with chemicals, and the flux is restored by aeration and flushing.