In-situ chemical oxidation (ISCO) is an effective technology for the remediation of organic contaminated soils and groundwater, as it has high contaminants removal rates and offers the possibility of fast treatment. As an in-situ remediation technology, ISCO can be also used for minimizing contaminants dispersion and lowering the overall treatment cost. Persulfate (PS) is an emerging and promising oxidant for in-situ soil and groundwater remediations due to its high redox potential (E⁰=2.01 V), long-term stability, high-water solubility, easy transport and wide operative pH range. It can be thermally or chemically activated by initiators to form sulfate radical (SO₄^·-), a strong oxidant (E⁰ =2.60 V) which has been successfully used for environmental applications in the remediation of aqueous and sediment systems. The activation methods include UV, heat, transition metals ions, alkaline condition and PS combined with other oxidants. Therefore, the application of activated persulfate (APS) oxidation has emerged as a novel ISCO. This paper provides an overview of mechanism and research progress of APS oxidation. It also reviews the engineering application of APS oxidation technology such as synergistic and hyphenated action for remediation of organic contaminated soils and groundwater, and points out the prospects of the research areas meriting further investigation and development trends.

Contents
1 Introduction
2 Mechanism and research progress of activation oxidation
2.1 Methods of activation and reaction mechanism
2.2 Heat activation
2.3 Transition metals activation
2.4 Alkaline activation
2.5 Combination of other oxidants
2.6 Research areas meriting further investigation and development trends
3 Engineering application of APS
3.1 Synergistic activation of PS
3.2 Integration of APS with other processes
4 Conclusion and perspective