Caustic Brine Recovery - Sugar Refinery

The refinery followed the method to reduce the pH from the existing 12 to 8 pH so that the Nanofiltration membrane supplied by their supplier could tolerate the brine solution. However, the membranes could not accept harsh conditions like high pH and High Temperatures up to 70 Deg C.

Diva Envitec Pvt Ltd having rich experience in Brine recovery systems, was approached, and we gave our High pH and High-temperature resistant nanofiltration membranes. The membrane construction was Surface  Modified with Charge, and the Zeta Potential played an essential role in separation.

Capacity of the Brine flow was 12 m3/Hour  –  NaOH 2%; NaCl 10%.

Design parameter: 8400 hours per year(24 h/d, 350 d/year), @70 ℃.

In the Conventional system, they were using Acid HCl approx 1747 Tonnes/Year, and Caustic makeup was approx. 1915 Tonnes /year. The plan had 60 membranes of neutral pH membranes installed. 

The client faced regular fouling of membranes. The flux dropped after one season and colour passage after two seasons. The changeover of the membrane was very costly every year.  

The cost of cooling the brine was high, as their existing membrane could not use high temperatures. 

• Diva Envitec proposed to replace the existing membranes with Poresep membrine in their current system. The pumps remained the same. We could achieve the flow rate with approx. Forty-eight membranes were installed. 
• The client did the necessary piping modifications. 
• They did not have to cool down the Brine now. 
• No HCl Dosing was required in our new modified system.
• Up to 90% Recovery was achieved compared to only 40-50% recovery earlier with their old membranes. 
• Diva Envitec has proposed their Tubular reactor to recover the 10% and make the plant 100% recovery basis. 
• With the last change, no Coloured brine will go to ETP, and the client will solve their discharge problem.  

After making the above changes, the BRS is functioning efficiently now. No choking is reported. No Flux drop is seen.