Cheng-Han Lee

This Editorial introduces the Special Issue “Emerging Technologies for Waste Treatment, Pollution Control and Resource Recovery”, which examines how contemporary environmental engineering is moving beyond conventional end-of-pipe treatment toward integrated, circular, and systems-oriented approaches. The collected contributions address sustainability innovation in textile manufacturing, life-cycle-informed PFAS removal from landfill leachate, fishbone-derived hydroxyapatite adsorbents for heavy metal removal, and constructed wetlands for azo dye degradation. Together, these studies demonstrate that effective waste treatment must be evaluated not only in terms of pollutant removal efficiency, but also by material circularity, secondary environmental burdens, operational feasibility, and long-term contaminant fate. This Editorial highlights key cross-cutting themes, including the valorization of residual materials, the importance of realistic matrices and field validation, and the need to integrate life cycle assessment, techno-economic analysis, and mechanistic investigation early in technology development. It further identifies major research gaps concerning spent media management, regeneration, toxicity, transformation products, and scale-up under variable operating conditions. Overall, this Special Issue proposes a framework in which emerging waste treatment technologies are understood as multifunctional environmental systems that support pollution control, resource recovery, and resilient circular economies.

Desalination brine is a concentrated stream that is generated during the desalination process. Brine commonly has high salinity and TDS (total dissolved ions), which contains ions such as Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, SO₄²⁻, HCO₃⁻, PO₄³⁻, and some critical elements. Currently, the brine treatment mainly applies direct disposal, like surface water discharge, sewer discharge, deep‐well injection, and evaporation ponds. However, these methods can cause harm to marine ecosystems, soil, and groundwater. Therefore, brine can be regarded as a resource to be reutilized. This work then aims to highlight the novel developments of brine application. For example, Na, Ca, and Mg in brine can be employed for carbon capture and utilization with ammonia, amines, and alkaline substances. With slight adjustment, brine can also be directly used as irrigation water, aquaculture water, and the activation of biochar. Furthermore, brine holds a higher concentration of critical elements, which makes many countries and scholars start to conduct element extraction, reducing the amount of ore exploitation. At last, the major obstacles related to these advancements in sustainability, expenses, and technological aspects are outlined, and promising research trends of brine reutilization are also suggested.