The Removal Efficacy of Heavy Metals and Total Petroleum Hydrocarbons from Contaminated Soils by Integrated Bio-phytoremediation

Abstract

ABSTRACT In this study, the bio-phytoremediation and phytoremediation technologies were applied to the soils contaminated withtotal petroleum hydrocarbons (TPH) and heavy metals to evaluate the remediation efficacy from May 2012 to December2013. Poplar (Populus bonatii Levl.) and Sun Hemp (Crotalaria juncea L.) were selected and planted in phytoremediationpractice. These plants were also utilized in the bio-phytoremediation practice, with the addition of earthworm (Eiseniafetida) and petroleum-degrading bacteria (Pseudomonos sp. NKNU01). Furthermore, physiological characteristics, such asphotosynthesis rate and maximal photochemical yield, of all testing plants were also measured in order to assess theirhealth conditions and tolerance levels in adverse environment. After 20 months of remedial practice, the results showedthat bio-phytoremediation practice had a higher rate of TPH removal efficacy at 30-60 cm depth soil than that ofphytoremediation. However, inconsistent results were discovered while analyzing the soil at 100 cm depth. The study alsoshowed that the removal efficiency of heavy metals was lower than that of TPH after remediation treatment. The resultsfrom test field tissue sample analysis revealed that more Zinc than Chromium was absorbed and accumulated by the testedplants. Plant height measurements of Poplar and Sun Hemp showed that there were insignificant differences of growthbetween the plants in remediation plots and those in the control plot. Physiological data of Poplar also suggested it hashigher tolerance level toward the contaminated soils. These results indicated that the two testing plants were healthy andsuitable for this remediation study.Keywrods: Total petroleum hydrocarbons (TPH), Bio-phytoremediation, Phytoremediation, Earthworm, Petroleum-degrading bacteria, Poplar, Sun Hemp