A Please find the below infograph for the answer. 

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, 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.) .