Review Paper Legacy 1,2,3-trichloropropane contamination: a systematic review of treatments B. Hope Hauptman and Colleen C. Naughton ABSTRACT 1,2,3-Trichloropropane (TCP), a suspected human carcinogen, is a widespread contaminant that leaches into groundwater, where it persists. This systematic review of studies examines treatment technologies for TCP contamination. A four-database search yielded 1,160 papers, 36 of which met the eligibility criteria for a full-text review. The three most-represented treatment technologies, such as biodegradation (13), zerovalent transition metals (8), and granular activated carbon (GAC) (4), are either fully deployed in water systems or in the field test stage. To meet TCP treatment goals, additional site-specific testing of well water is needed since source water chemistry and co- contamination influence treatment efficacy. Future studies should include standardized units for reporting degradation or sorption normalized to surface area, chemical input, and/or energy expenditures. Although GAC is the most common treatment for contaminated wells, this technology remains limited due to a low TCP adsorption capacity which requires frequent bed-volume replacement. Aerobic biodegradation, reduction with zerovalent iron, and Fenton’s treatment produce byproducts that could limit their use. A geospatial analysis of TCP treatment studies reveals a dearth of knowledge about the extent of TCP contamination. TCP contamination is documented in at least nine countries on three continents, but there is little information about the rest of the world. Key words | 1,2,3-TCP, granulated activated carbon (GAC), groundwater treatment, legacy contaminant, United Nations Sustainable Development Goal 3 and 6 HIGHLIGHTS • First systematic review of 1,2,3-trichloropropane (TCP) treatment studies. • The most highly developed technologies are GAC, zerovalent zinc, and bioremediation. • Source water chemistry and co-contamination influence TCP treatment efficacy. • Studies need standardized TCP removal reporting units normalized to the surface area. • TCP contamination studied in only three continents, revealing wide knowledge gaps. B. Hope Hauptman (corresponding author) Environmental Systems Graduate Group, University of California Merced, 5200 N. Lake Rd., Merced, CA 95343, USA E-mail: bhauptman@ucmerced.edu Colleen C. Naughton Department of Civil and Environmental Engineering, University of California Merced, 5200 N. Lake Rd., Merced, CA 95343, USA This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/). 1 Review Paper © 2021 The Authors Journal of Water, Sanitation and Hygiene for Development | in press | 2021 doi: 10.2166/washdev.2021.006 Corrected Proof Downloaded from http://iwaponline.com/washdev/article-pdf/doi/10.2166/washdev.2021.006/882840/washdev2021006.pdf by guest on 11 June 2021