Study on biomonitoring of aged TPH-contaminated soil with bioaugmentation and biostimulation

The contaminated site of aged total petroleum hydrocarbons (TPH) in the southeast of Taiwan was a storage-oil factory. The objective of this study was to find a optimized technology to remediate and/or restore this site. A field trial was performed by lab. scale biopiles, The soil biopile set comprised four different factors of experimental design in the glass bottles loaded by 2kg of contaminated soil. 1. Well-mixed biopile with the indigenous microbes as control test, CT. 2. Combined bioaugmentation and biostimulation with TPH-degrading bacteria and biosurfactant, BAS. 3. Organic carbon source biostimulation and bioaugmentaion with kitchen waste compost, KW. 4. Nutrient enhancement with NH4NO3, K2HPO4, NE. Moisture content was maintained around 15-25% and the temperature range was controlled at 30±2°C. Before 180 days, the TPH concentration was decreased from13,878±218 mg TPH/ kg dry soil to 2,881±248 mg TPH/ kg dry soil and the removal efficiency was 79% in CT biopile. The best biodegradation of TPH was KW biopile (the removal efficiency =89%). Others, the removal efficiency of BAS biopile was 86% and NE biopile was 84%. Before 35 days, the first-order reaction rate constant K values (day-1) of four biopiles was evaluated as NE(0.04)>BAS(0.0329)>KW(0.0123)>CT(0.0084). Molecular biomonitoring methods were developed to identify the TPH-degrading bacteria existed in all biopiles: Microarray biochip could identify more species of the TPH-degrading bacteria and fungi. This study was showed that enhanced biodegradation processes and the degree of composting compositions were respectively inoculated in the composting process. This pilot study of six months of biopile farming approved that bioaugmentation and biostimulation could enchance the bioremediation of TPH contaminated soil.