Electrophoretic ultrafiltration recovery system

Ultrafiltration (UF) consists of membrane modules, pumps, piping and instrumentation, usually equipped with filtration and cleaning systems to ensure the proper operation of ultrafiltration units. Ultrafiltration is a pressure-driven membrane separation process, using a special semi-permeable membrane to intercept high molecular weight (more than 5000) substances (pigments, resins), so that the solute in the solution with a molecular weight less than the intercepted molecular weight (inorganic heteroions, low molecular weight resin, solvent and water) passes, so ultrafiltration can be used to control the content of heteroions in the electrophoresis bath, and the separated "water (UF liquid)" can be used to rinse the workpiece coated with electrophoretic paint, so that the floating paint brought out is returned to the electrophoresis tank, this technology is called " closed circuit flushing".
Ultrafiltration membrane modules are divided into plate and frame type, hollow fiber type, coil type, tubular type, etc. according to the shape of the membrane support, and the latter two are the most popular. For UF membranes with good performance, the UF liquid flow rate should be 20~50L/(m2·h).
Ultrafiltration systems are generally provided by ultrafiltration membrane manufacturers. Different manufacturers have different requirements for the process and supporting system, but as an auxiliary part of the electrophoresis device, there are some common requirements introduced here.
The specifications of the UF device are designed and selected: UF liquid production (m/h) = swimming coating area (m/h) x (12~15)(L/m2) x coefficient (generally 12~13). The amount of electrophoresis tank liquid supplied to the UF device should be 20 times the output of UF liquid, and a bag filter is provided in front of the ultrafilter (the filtration accuracy is generally 100~150μm, and the filtration accuracy required for the coiled UF filter is 25μm).
UF liquid pipelines, valves, etc. are made of stainless steel, UF liquid storage tank and UF device cleaning tank can be made of stainless steel, FRP or plastic, UF liquid storage tank volume should be able to store the flow of the device for 2~3h. Question I
To design a line that allows the UF liquid to return the UF liquid directly from the UF unit to the electrophoresis tank, there must be a temperature interlock alarm system that can stop the system at a specified high temperature limit, and overheating will damage the UF membrane.
The effluent capacity of UF units decreases with increasing operating time. When the flow rate drops to 70% of the design flow, cleaning should be carried out, so the UF device design flow should be larger, even at low flow conditions, it can ensure the requirement of 1.2L of coating area per square meter.
Also consider the ability to automatically replenish the system with fresh deionized water when the UF liquid is discharged from the purified electrophoresis tank.

The role of ultrafiltration device for electrophoretic paint
1.Recover the electrophoretic paint washed off the surface of the workpiece to avoid environmental pollution caused by the discharge of waste water with paint.
2.The ultra-filtered water newly produced by the device provides washing water for workpieces exiting the electrophoresis tank, which can form a closed-circuit circulating water washing system.
3.By properly discharging the ultrafiltrate, remove various ions brought into the electrophoretic paint tank during the production process, and stabilize the electrophoretic paint working fluid.
4.Reusing the recovered electrophoretic paint can save 30% of the purchase cost of electrophoretic paint for enterprises.
5.Stabilize the tank solution and improve the quality of the paint film