Recovery of baker’s yeast wastewater with membrane processes for agricultural irrigation purpose: Fouling characterization

• Agricultural irrigation is the largest usage of fresh water.
• Baker’s yeast wastewater was treated by two-step NF process.
• Desal 5DL was determined as appropriate membrane for membrane selection.
• The lowest flux decline was obtained at pH 7, 12 bar, 25 °C.
• Agricultural irrigation water quality was achieved by two-step NF process.

Increasing water demands for both industrial and public uses as well as more restrictive laws make the industrial wastewater recovery necessary. In this study, it was aimed to propose membrane treatment process for recovery of biologically treated baker’s yeast wastewater to the degree of agricultural irrigation water quality. In addition to water recovery, membrane fouling mechanism was investigated. Membrane selection was carried out using FM UP020, FM UP005, NF 270, NF 90 and Desal 5DL membranes. Desal 5DL membrane was selected as appropriate membrane for baker’s yeast wastewater treatment according to relatively higher rejection performance, lower flux declines and lower increase in contact angle. The effects of pH, temperature, and transmembrane pressure (TMP) were investigated on Desal 5DL membrane fouling. In addition, atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy measurements were used for fouling characterization. NF 90 membrane was determined as suitable membrane to increase the quality of composite permeates obtained from Desal 5DL membrane. As a conclusion, the treated baker’s yeast wastewater by two-step nanofiltration (NF) process was classified as class B in terms of pH, biological oxygen demand (BOD5), suspended solids (SS) and fecal coliform parameters. II. Class irrigation water was achieved for degree of restriction on irrigation use.