Exploiting constructed wetlands for industrial effluent phytodesalination in Jing-Jin-Ji urban agglomeration, China

Novelty statement The exploitation of phytoremediation via local halophytes for treating salt-laden industrial water discharges, with specific reference to the Beijing-Tianjin-Hebei (Jing-Jin-Ji) urban agglomeration, has not been explored nor reported in the literature. This study addresses these critical knowledge gaps, providing new insights and technical considerations for workable large-scale phytodesalination applications for deploying and implementing constructed wetlands using locally available halophytes suited to Jing-Jin-Ji agglomeration. This distinguishes this pertinent study intended to engage researchers, industrials, and other stakeholders in the focus area and beyond. The unsustainable exploitation of water resources and growing salinization impacting China's Beijing-Tianjin-Hebei (Jing-Jin-Ji) agglomeration threatens the region's economic growth and drives the exploration of alternative resources. The region's industries face a financial burden due to increasing constraints on water exploitation and discharge regulations. These have resulted in increased industrial salt concentration rejections/discharges, meanwhile, constructed wetlands (CWs), deployed as a perfunctory receptacle for industrial effluents in the region, are underexploited for treating/removing salts. Also, halophytic plants local to the region have promising chloride uptake (60.6 g/kg and 256.0 g/kg of plant dry weight) and can reduce water conductivity by 40%. Exploitation of CWs, using local halophytes has not been explored for phytodesalination purposes in the region. Hence, this study analyses the water resource and salinization crisis in the agglomeration and further evaluates workable potential and critical technical considerations for using local halophytes in CWs to treat industrial salt-laden effluents. While acknowledging this intervention for removing industrial effluent salt may not meet compliance in the region, effluent post-phytodesalination presents opportunities for industries to meet regulatory stipulations on water reuse rates. Furthermore, such effluent may be used for irrigation and can ameliorate the salinization and groundwater exploitation crisis as a cleaner recharge source.