Comprehensive review of conventional and emerging technologies for advanced primary wastewater treatment with an insight into future perspectives

Advanced primary treatment (APT) technologies are increasingly recognized as key components in the development of next-generation wastewater treatment plants (WWTPs), driven by their high pollutant removal efficiency, reduced energy demand, and contribution to climate-neutral operation. This review systematically evaluates the performance of major APT processes - including chemically enhanced primary treatment (CEPT), microsieving, flotation, electrocoagulation, integrated systems, and conventional sedimentation. Multiple visualization tools were applied to compare removal efficiencies and operational characteristics across technologies. The analysis demonstrates that all advanced techniques consistently outperform conventional gravity-driven sedimentation, highlighting the limitations of traditional primary treatment. Electrocoagulation and integrated systems achieve the highest overall removal efficiencies across multiple parameters, while CEPT, flotation, and microsieving exhibit strong performance in removing suspended solids, turbidity, and particulate-bound organic matter. However, these latter technologies show limited and highly variable nutrient removal, particularly for total nitrogen, reflecting both inherent process constraints and a lack of comprehensive studies.In addition, the review assesses economic and environmental aspects, revealing that microsieving and sedimentation offer lower costs and reduced carbon footprints, albeit with limited nutrient control. In contrast, electrocoagulation and integrated systems provide superior treatment performance at higher capital and operational costs, restricting their application to plants facing stringent effluent requirements.