Coupling of desorption of phenanthrene from marine sediments and biodegradation of the sediment washing solution in a novel biochar immobilized-cell reactor

Environ Pollut. 2022 Sep 1:308:119621. doi: 10.1016/j.envpol.2022.119621. Epub 2022 Jun 13.

Abstract

The recurrent dredging of marine sediments needs the use of ex-situ technologies such as sediment washing (SW) to effectively remove polycyclic aromatic hydrocarbons. Notwithstanding, the large volumes of generated spent SW effluents require adequate treatment by employing highly-efficient, inexpensive and environmentally-friendly solutions. This study proposes the phenanthrene (PHE) desorption from sediments using Tween® 80 (TW80) as extracting agent and the treatment of the resulting spent SW solution in a biochar (BC) immobilized-cell bioreactor. The SW process reached the highest PHE removal of about 91% using a surfactant solution containing 10,800 mg L-1 of TW80. The generated amount of spent PHE-polluted SW solution can be controlled by keeping a solid to liquid ratio of 1:4. A PHE degradation of up to 96% was subsequently achieved after 43 days of continuous reactor operation, aerobically treating the TW80 solution in the BC immobilized-cell bioreactor with a hydraulic retention time of 3.5 days. Brevundimonas, Chryseobacterium, Dysgonomonas, Nubsella, and both uncultured Weeksellaceae and Xanthobacteraceae genera were mainly involved in PHE biodegradation. A rough economic study showed a total cost of 342.60 € ton-1 of sediment, including the SW operations, TW80 and BC supply and the biological treatment of the SW solution.

Keywords: Biochar; Bioreactor; Cost evaluation; Non–ionic surfactant; Polycyclic aromatic hydrocarbons; Sediment washing.

MeSH terms

  • Biodegradation, Environmental
  • Charcoal
  • Geologic Sediments
  • Phenanthrenes* / metabolism
  • Polycyclic Aromatic Hydrocarbons* / metabolism

Substances

  • Phenanthrenes
  • Polycyclic Aromatic Hydrocarbons
  • biochar
  • Charcoal