Influence of Bulking Agents, Fertilizers and Bacteria on the Removal of Diesel from a Newfoundland Soil

Abstract

Laboratory experiments in culture flasks, containing diesel-contaminated Newfoundland soil samples, were undertaken to compare the influence of fertilizers, microorganisms and bulking agents on bioremediation. In Phase I experiments only one fertilizer (cow manure or poultry manure), one bulking agent (sand or hay), or one inoculum (cold-tolerant indigenous bacteria or exogenous commercial bacteria) was added to a soil sample. In Phase II experiments, Design-Expert® Version 6 design of experiment software determined the combinations of fertilizers, bulking agents and inocula to be mixed with the soil samples to study the interactions among the amendments. The maximum diesel removal at 90 days occurred in the sample with sand (Phase I) and in the sample with cow manure, an inoculum of cold-tolerant indigenous bacteria, and sand (Phase II). Diesel removal at 45 days for the same two samples was 85.4% (Phase I) and 91.9% (Phase II), suggesting the cow manure and/or cold-tolerant bacteria inoclum accelerated the process. The poultry manure, commercial bacteria and hay were less effective than their counterparts. The commercial bacteria were more sensitive to diesel concentration than the indigenous cold-tolerant bacteria. The addition of sand, cow manure, and poultry manure improved diesel removal.

Keywords:

• Aerobic biodegradation
• cold-tolerant bacteria
• cow manure
• poultry manure
• sand
• total petroleum hydrocarbons

Acknowledgements

The authors thank the personnel in the laboratories of the Faculty of Engineering and Applied Science and in the Biology and Chemistry Departments of Memorial University of Newfoundland and in Maxxam Analytics Inc., St. John's, for their contributions to this project. Memorial University of Newfoundland funded the research.

Notes

^a OD = Optical Density.

^b MSS = Mineral Salt Solution.

^c D = diesel.

^d PB I, PB II = samples 1 and 2 with Indigenous Cold-tolerant Bacteria.

^e CB I, CB II = samples 1 and 2 with Exogenous Commercial Bacteria.

^a Diesel removal values are for duplicate samples.

^b S = sand.

^c H = hay.

^d CB = commercial bacteria.

^e PB = cold-tolerant bacteria.

^f PM = poultry manure.

^g CM = cow manure.

^h AC = abiotic control and only autoclaved sample.

ⁱ NA = natural attenuation control without added nutrients, bulking agents or inocula.

^a Diesel removal values are for duplicate samples.

^b PM = poultry manure.

^c PB = cold-tolerant bacteria.

^d H = hay.

^e CM = cow manure.

^f CB = commercial bacteria.

^g S = sand.