Sustainable in situ remediation of recalcitrant organic pollutants in groundwater with controlled release materials: A review

David O'Connor, Deyi Hou, Yong Sik Ok, Yinan Song, Ajit K. Sarmah, Xuanru Li, Filip M.G. Tack

Research output: Contribution to journalReview articlepeer-review

159 Citations (Scopus)


The removal of recalcitrant organic pollutants in groundwater is a challenge being faced around the world. Achieving effective long-term remediation of contaminated aquifers faces a variety of significant issues such as back diffusion, tailing, and rebound. In recent years, some researchers have proposed the use of controlled release materials (CRMs) as a new approach to counteracting such issues. The novelty of CRMs lies in that they release their active products slowly, over prolonged periods of time, in order to sustain in situ treatments and long-term effectiveness. Here we review the main constituents of CRMs, analyze their production, characterization, and applications, with a focus on reaction mechanisms, effectiveness, and secondary effects. This review shows that the reactive components of CRMs most commonly involve either: (i) chemical oxidants to treat contaminants such as TCE, PCE, BTEX, and 1,4-Dioxane; (ii) sources of dissolved oxygen to stimulate aerobic biodegradation of contaminants such as BTEX and 1,4-Dioxane; or, (iii) substrates that stimulate reductive dechlorination of contaminants such as TCE and 1,2-DCA. It was found that in some studies, CRMs provided sustained delivery of CRM treatment reagents over several years, and achieved complete contaminant removal. However, lower removal rates were apparent in other cases, which may be ascribed to insufficient dispersion in the subsurface. There are a relatively limited number of field-scale applications of CRMs in contaminated land remediation. Those conducted to date suggest that CRMs could prove to be an effective future remediation strategy. Lessons learned from field applications, suggestions for future research directions, and conclusions are put forward in this review.

Original languageEnglish
Pages (from-to)200-213
Number of pages14
JournalJournal of Controlled Release
Publication statusPublished - 2018 Aug 10


  • Bioremediation
  • Controlled release
  • Groundwater remediation
  • In-situ chemical oxidation
  • Slow release materials

ASJC Scopus subject areas

  • Pharmaceutical Science


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