Recovery of Acid and Alkaline from Industrial Saline Wastewater by Bipolar Membrane Electrodialysis under High-Chemical Oxygen Demand Concentration

Abstract

Actual high saline wastewater containing concentrated organics and sodium chloride is a bioenergy and renewable resource. This study compared two different bipolar membrane electrodialysis membranes from two companies’ stacks to recover HCl and NaOH from sodium chloride solution and actual chemical wastewater. The results demonstrated that the electrolysis rates were around 1.5 kg/m2h, the HCl and NaOH production rates were about 0.9 kg/m2h, energy consumption was in the range of 1.05–1.27 kWh/kg, and the economic benefits were above 1 yuan/h in BMED systems. From analyzing the performance of seven different BMED membrane stacks, the B2 stack was chosen for electrolyzing actual high salt wastewater to observe the effect of chemical oxygen demand on BMED systems, where electrolytic salt performance, HCl-NaOH alkali production rates, and energy consumption show linear dependence on time for 5000 mg/L chemical oxygen demand wastewater. It illustrated chemical oxygen demand can enhance energy consumption and reduce electrolytic salt performance and the acid and alkali production rates, due to improving the membrane area resistance. In this study, the effect of high COD saline wastewater on the performance of a BMED membrane stack was clarified and the mechanism was analyzed for its practical application in treating chemical high salt wastewater.

Electrochemical Removal of Nitrogen Compounds from a Simulated Saline Wastewater

“…Discharging this saline wastewater into the environment can result in several problems, such as the contamination of various resources, the fluctuation of salinity levels of water bodies, and the eutrophication of lakes [ 4 , 5 ]. In general, saline wastewater is characterized by salt in the range of 1–3.5% w / w ; conversely, wastewater with higher salt content is defined as hypersaline [ 6 , 7 ]. Nevertheless, the salinity of the wastewater is affected by the different industrial processes involved.…”

In-Depth Study on the Effects of Impurity Ions in Saline Wastewater Electrolysis

“…However, the disposal of the mixed salt is a big problem that needs to be solved [ 4 ]. With the wide application of alkaline water electrolysis [ 5 , 6 , 7 ], advanced electrochemical technology [ 8 ], brine electrolysis technology in seawater desalination, chlor-alkali industry, and wastewater disposal [ 9 ], concentration followed by electrolysis becomes one of the most promising ways for saline wastewater treatment [ 10 ], as it could produce H 2 , Cl 2, and an alkaline solution with deacidification potential. Benefited by the advantages of the high purity of separated gas, ion exchange membrane electrolysis [ 11 , 12 ] is now the most common used technology in the brine electrolysis process, even though its electrolytic efficiency depends largely on the performance of the ion membrane.…”

Saline Wastewater: Characteristics and Treatment Technologies

“…The discharge of saline wastewater has significantly increased due to rapid urbanization and industrialization [ 1 , 2 , 3 ]. Saline wastewater contains substantial amounts of salt resources originating from various sources, such as NaCl from the coal chemical industry and Zn(II) from electroplating processes [ 4 , 5 , 6 ].…”