Details

Autor(en) / Beteiligte

• Hung, Pao-Chen
• Chang, Shu-Hao
• Ou-Yang, Chia-Chien
• Chang, Moo-Been

Titel

Simultaneous removal of PCDD/Fs, pentachlorophenol and mercury from contaminated soil

Ist Teil von

• Chemosphere (Oxford), 2016-02, Vol.144, p.50-58

Ort / Verlag

England: Elsevier Ltd

Erscheinungsjahr

2016

Quelle

MEDLINE

Beschreibungen/Notizen

• Pentachlorophenol (PCP), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and mercury were simultaneously removed from heavily contaminated soil using a continuous pilot-scale thermal system (CPTS). Operating the system at 700 °C with 22 min of retention time ensured that the residual contaminants in remediated soil are lower in concentration than the soil standards of Taiwan EPA require. Both PCP and PCDD/Fs are effectively destroyed during the treatment at high temperatures in the CPTS, but significant dechlorination of PCDD/Fs is also found, resulting in lower net destruction efficiencies of TCDD/F and PeCDD/F-congeners, compared with those of highly chlorinated Hx-, Hp- and OCDD/F congeners. Moreover, 2,3,7,8-TetraCDD is significantly formed if the retention time is not long enough for total destruction. Inadequate reaction time (or retention time) even may lead to a rise in TEQ-value due to incomplete dechlorination. Mercury is significantly desorbed from contaminated soil and discharged through the exhaust. For PCP and PCDD/Fs, the exhaust discharge percentages including both the remediated soil and the exhaust are <0.03% and 1.14% of the input, respectively, achieved with 700 °C and 33 min retention time. In contrast, some 97.8% of input mercury rate is desorbed and discharged via the exhaust, so that the latter should be carefully cleaned via efficient air pollution control devices, whereas this contribution focuses on the conditions required for reaching adequate soil cleaning. •Pyrolysis is applied for simultaneous removal of multi-pollutants from soil.•An innovative continuous system for soil remediation is developed and applied.•High PCP, PCDD/F and mercury removal efficiencies are obtained.•Operating the system at 700 °C with retention time of 22 min meets the regulation.•Dechlorination is an important pathway for PCDD/F degradation.