Effect of vitamin supplementation on biodegradation of aliphatic hydrocarbons and diesel fuel.

摘要

Bioremediation of hazardous wastes is proven to be environmentally benign and most cost effective technology when proper conditions are provided. However, commercialization of this method still requires comprehensive research to enhance the degradation rate to make the technology more acceptable for implementation. In this research a unique approach to increase the rate of biodegradation by vitamins supplementation was studied.; Five vitamins, niacin, biotin, folic acid, thiamin and pantothenic acid were selected for the present study. Different short chain {dollar}(rm Csb8{dollar} and {dollar}rm Csb9),{dollar} and long chain {dollar}(rm Csb{lcub}16{rcub}{dollar} and {dollar}rm Csb{lcub}17{rcub}){dollar} aliphatic hydrocarbons and diesel fuel (a mixture of {dollar}rm Csb7{dollar} to {dollar}rm Csb{lcub}23{rcub}){dollar} were tested as the target compounds. The effects of the specific vitamins and mixture of vitamins on biodegradation of target compounds were investigated using a microbial consortium obtained from soil.; The degradation rate as well as the microbial growth were monitored. The optimal vitamin concentrations were experimentally determined. Then the kinetics of degradation of {dollar}rm Csb8, Csb9, Csb{lcub}16{rcub}{dollar} and {dollar}rm Csb{lcub}17{rcub}{dollar} were studied. For diesel, the degradation kinetics and also the fractionation pattern were investigated.; The results showed that the vitamin mixture was more effective than the individual vitamins. Individual vitamins were often inhibitory at certain concentrations. Therefore one needs to optimize individual vitamin concentrations to get the best effect. The effectiveness of arbitrary vitamin mixture (contained each of five vitamins at the same concentration) was less than the optimized vitamin mixture which contained niacin, biotin, folic acid and pantothenic acid at their optimum concentrations.; The effectiveness of the optimized vitamin mixture was most prominent in reduction of lag phase, increasing overall growth rates and overall degradation rates. It has been found that the lag phase was reduced by 13 to 50% with optimized vitamin mixture as compared to that without vitamin. The lag phase reduction was very significant for nonane and heptadecane degradation. The overall growth rates and overall degradation rates increased significantly (increased by average 36% and 31% respectively) with optimized vitamin mixture supplementation.; Increase of specific growth rates and degradation rates during exponential phase of microbial growth with the optimized vitamin mixture were not noticed in all cases. Although in some cases specific growth rates increased significantly.; Therefore it can be said that vitamins play important role to initiate growth of soil microbes and help them to degrade various hydrocarbons faster. Hence, vitamin supplementation can enhance the biodegradation of hydrocarbons on soil.