Life cycle cost analysis of desalinating small wastewater flows in the food and beverage industry

Certain sectors of the food and beverage industry that produce saline wastewater (WW) may be required to desalinate their final effluent; whether with the aim of reusing the treated WW or simply to comply with discharge limits. Reverse osmosis (RO) is an energy-intensive desalination process, in which energy consumption is dependent on salinity concentration, flow rate, and desired water recovery percentage. The advent of the energy recovery device (ERD) allows for the recovery of energy from the brine flow in an RO system. However, there is a trade-off between the cost savings from the recovered energy and the cost of a brine disposal. To assess the value of employing an ERD, life cycle cost analysis (LCCA) was conducted using the net present value (NPV) method on a RO system treating wastewaters with similar characteristics to those of a tannery and an aquafarm. The results showed that the value of employing an ERD is highly dependent on the cost of brine disposal, and less on the water that is produced. For inland sites that do not have the option of discharging brine into the sea, the cost of brine disposal can outweigh the economic gains from energy recovery.