Techno-economic analysis of integrated bipolar membrane electrodialysis and batch reverse osmosis for water and chemical recovery from dairy wastewater

Bipolar membrane electrodialysis (BMED) for acid and base recovery and batch reverse osmosis (BRO) for water recovery are analyzed technically and economically as a dairy wastewater treatment solution. The proposed process layouts also aimed to utilize recovered water and chemical within same industrial plant. The hybridization of BMED with BRO process is used to reduce capital and operating cost of BMED unit and compared with the standalone BMED process. The analysis reveals that the hybridization of BRO-BMED system achieve 25.8% less unit cost and three times higher concentration of acid and base chemicals compare to standalone system. The comparison of system is done at optimum current density of BMED process and permeate flux of BRO process. Sensitivity analysis of permeate flux, current density and feed salinity is carried out. The higher feed concentration is desirable and reduces the cost in BMED process and same with current density but up to 409 and 255 A/m2 in hybrid and standalone system respectively. In hybrid system, the multi-response surface analysis observes that higher permeate flux in BRO reduces the BMED cost but increases the BRO cost and the minimum cost of 14 USD/kmol is achieved at 26 LMH permeate flux.