Wastewater treatment research focuses on removing pollutants efficiently while recovering valuable resources. One major area is advanced oxidation processes that use powerful reactive species, such as hydroxyl and sulfate radicals, to degrade persistent organic contaminants. Recent work explores combining oxidants, catalysts, and ultraviolet or visible light to enhance degradation rates and lower energy use.

Membrane technologies are another important focus. Researchers study ultrafiltration, nanofiltration, and reverse osmosis to separate contaminants, including microplastics, pharmaceuticals, and dyes. Key challenges include membrane fouling and operational costs, so new materials, surface modifications, and hybrid membrane systems are being developed to improve flux, selectivity, and durability.

Biological treatment remains central. Studies investigate activated sludge, biofilms, and granular sludge for removing organic matter and nutrients. Attention is turning to microbial community dynamics, metabolic pathways, and the integration of aerobic and anaerobic processes. Anaerobic digestion is particularly attractive because it can convert organic pollutants into biogas, supporting energy recovery and circular economy goals.

Electrochemical methods are emerging for targeted removal of difficult pollutants, disinfection, and in situ generation of oxidants. Research aims to design efficient electrodes, reduce energy consumption, and couple electrochemical steps with biological or membrane treatments.

There is strong interest in treating industrial effluents, such as textile dye wastewater, pharmaceutical wastewater, and leachate, which often contain toxic, recalcitrant compounds. Hybrid systems that combine physical, chemical, and biological processes are studied to meet strict discharge and reuse standards.

Across all approaches, key trends include resource recovery, modular treatment units, integration of renewable energy, and the development of low cost materials suitable for use in regions with limited infrastructure.