Profiles and removal efficiency of organochlorine pesticides with emphasis on DDTs and HCHs by two different sewage treatment works

Yu Bon Man, Ka Lai Chow, Zhang Cheng, Yuan Kang, Ming Hung Wong*

*Corresponding author for this work

    Research output: Contribution to journalJournal articlepeer-review

    15 Citations (Scopus)

    Abstract

    The removal efficiencies of nine organochlorine pesticides (OCPs) were investigated in two sewage treatment works (STWs; Stonecutter Island [SCI] and Shatin [ST]). The levels of OCPs in sewage samples collected from SCI (chemically enhanced primary treatment) and ST (secondary treatment) were determined with gas chromatography–mass spectrometry. The crude sewage in the two STWs generally had low levels of total hexachlorocyclohexane (HCHs; total of alpha-, beta- and gamma-HCH; SCI, 19.4 ± 4.62 ng/L; ST, 12.1 ± 4.27 ng/L) and total dichloro-diphenyl-trichloroethane (DDTs; total of p,p’ and o,p’-DDE, -DDD and -DDT; SCI, 6.31 ± 2.83 ng/L; ST, 6.09 ± 1.67 ng/L). High total removal efficiencies for total HCHs (SCI, 79.9 ± 7.03%; ST, 82.5 ± 2.51%) and total DDTs (SCI, 96.1% ± 3.37%; ST, 99 ± 0.501%) were observed. In particular, ST achieved outstanding performance in the removal of heptachlor (100% ± 0.00%), heptachlor epoxide (94.8 ± 3.96%), hexachlorobenzene (99.7 ± 0.387%), gamma-HCH (100 ± 0.00%) and total DDTs (99.2 ± 0.644%). There was no observable correlation between the removal efficiencies and the log Kow values of individual OCPs, which suggests that the removal mechanisms may not be related to sorption by particulate matter. Removal of OCPs seems to rely more on other mechanisms such as volatilisation, advection and biotransformation. This study is the first to investigate the fate and distribution of OCPs throughout the entire sewage treatment process. The results provide valuable reference for potential modification of sewage treatment processes with regard to OCPs.

    Original languageEnglish
    Pages (from-to)220-231
    Number of pages12
    JournalEnvironmental Technology and Innovation
    Volume9
    DOIs
    Publication statusPublished - Feb 2018

    Scopus Subject Areas

    • Environmental Science(all)
    • Soil Science
    • Plant Science

    User-Defined Keywords

    • DDT
    • HCH
    • OCPs
    • Removal efficiencies
    • Sewage sludge

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