A Since caustic and acids are mostly used for cleaning purposes, considering the aggressiveness and high temperature of the solution, we recommend ceramic or stainless steel membranes. Depending on the pore size of the membrane, caustic and acid can be separated from dissolved and suspended matters and reused again. There are cases of using stainless steel membranes in several textile mills which recover and reuse 90%+ of caustic solution. There are also cases in the food processing industry, where ceramic membrane is used to recycle caustic solution for cleaning processing lines. In some applications, a high PH tolerant Nano membrane is placed after the ceramic to remove the color of the caustic solution to make it a clear solution.  In applications that consume large amounts of caustic and acids such as the textile industry, food processing industry, and dairy industry, the inorganic membrane solution usually results in significant savings in chemicals, energy, and waste treatment costs.
For case details we did in Thailand for one of the biggest food processing manufactures in Asia, you can click below link or write us an email. https://www.innosep.co.th/Acid-Caustic-Recovery-pd48135119.html  
 

A Yes. The membrane can be used in soybean protein separation. The designed process includes steps of Soaking, Blanching, Grinding, Filtering/Centrifugation, UF and RO.
The blanching step is to prevent lipoxygenase-induced off-flavors during grinding. Filtration/centrifugation serves to remove insoluble carbohydrate and fiber to ensure the particle size is appropriate to the membrane being used.
Traditional processing techniques for producing soy protein concentrates involve extraction, heat treatment, and centrifugation which are time-consuming and sometimes result in products with poor functional properties, and they can generate a whey-like wastestream that contains a significant portion of the proteinaceous compounds of the soybean. The process of soy products by UF membrane usually results in higher yields because of the inclusion of the whey proteins that are normally lost in conventional processes. These whey proteins could also be contributing to the superior functional properties of the UF soy products, in addition to the benefits of the nonthermal and nonchemical nature of the UF process.

A Usually there are 3 main indexes to observe to determine the necessary cleaning.

1. Differential pressure across the system. If the differential pressure between feeding and rejection is greater than 10-15%, cleaning should be implemented.
2. Normalized product flow. If the normalized product flow decreases 10%+, cleaning should be implemented.
3. Salt rejection. If the salt rejection decreases 10%+, clean the membrane.

A Usually, we use tubular UF membrane for such application. UF tubular membranes are most suitable for this process and used in Thailand and Philippines. It is also possible for a pre centrifuge/decant of the first extracted juice and removal of most of the suspended solids and then use Spiral UF membrane with larger spacer too (used in Thailand only one factory).
We worked with clients on juice and wine clarification applications before. We do have test unit in our factory which can do test and pilot run.
If you need budgetary estimation, we will need more details on juice characteristics (TS, Brix, Temp, Appearance in a clear beaker picture etc.) .

A To clean the membrane, we can do both onsite and offsite.
There are general procedures to follow through:
1. A chemical cleaning that is to remove foulants, scales.
2. A biological cleaning to make the membrane free of microorganisms.
Four factors that would determine the efficiency of the cleaning.
1. Type of chemical chosen to use. This determines a membrane’s ability to withstand the action of the chemical cleaners. Some membranes have low tolerance to PH and temperature, and some are sensitive to chlorine.
2. Temperature. In general, the warmer the solution, the more effective is the cleaning process.
3. Flow rate. Higher velocities in pipelines is preferred.
4. Time of cleaning.

Let us know your membrane type and your process in operation. We could advise you on the chemicals for cleaning and the standard of operation to operate. Depending on the size complexity of your operation, it may be hard for you to implement the cleaning by yourself.  

Almost forgot, the most important rule of cleaning membrane is never to let the membrane dry out after contact with the process stream.

A
Short life of membrane occurs usually due to membrane fouling. Short life of membrane means that membrane get fouled too quickly. There are 3 main factors that affects membrane fouling.1. Membrane system design 2. Inlet water properties 3. And operating conditions. Following above 3 factors you can take below actions to find out why.

1. Conduct a water analysis to find out the feeding water quality. Pay more attention to the TDS level, Iron, Hardness level,SDI etc. If you also have Silica in the water, depending on the ppm level, you may need special chemical to take care the Silica aside from other salts which can be treated by water softeners.
2. Send us your system design, number of membranes, number of stages, piping material, sizing, pump and operation sequence.
3. Collect a data log of flow rate, temperature, conductivity, pressure on both inlet and permeate of each stage. Share with us the process diagram of your RO system including pre-treatments specifying pump models and working pressures.
4. Share with us your maintenance schedule including CIP frequency and the SOP of your maintenance work.
5. Give us more information such as if you use any bypass, auto flush, etc and intervals.