29-12-2012, 04:43 PM
Biodegradation of petroleum oil achieved by bacteria and nematodes
in contaminated water
1Biodegradation of petroleum.docx (Size: 192.65 KB / Downloads: 94)
Introduction:
Petrolium hydrocarbon pollution are formed due to industrial wastes like oil refineries or shipyard, also the leakage from storage tank of oil in water and soil causes its contamination. The major pollutants found in these industries are petroleum hydrocarbons, specifically aliphatic hydrocarbons, arising from storage of crude oil, spills .monoaromatic hydrocarbon caused by realese of petrol ,diesel and oil mix into water leading to its contamination. Gasoline is typically composed of 41–62% aliphatic hydrocarbons, with the remainder being aromatic hydrocarbons including a benzene, toluene, ethylbenzene, and xylene (BTEX) fraction of 10–59%. All major BTEX components are listed in united states environmental protection agency(USEPA). The aromatic hydrocarbons are generally more toxic than aliphatic compounds with a similar number of carbon atoms and have more mobility in water due to their solubility being 3–5 times higher . Diesel oil is a complex fuel mixture primarily consisting of paraffinic, olefinic, and aromatic hydrocarbons, and smaller quantities of substances containing sulfur, nitrogen, metals, andoxygen. The hydrocarbon molecules contain from 8 to 40 atoms of carbon, and are generally heavier than those found in gasoline.
Overview of the process:
The main approch of these work is to reduce the ground water contamination specially diesel oil using bacteria and nematodes. The bacterial and nematode counts are carried out in the lab analysis. The overall experiment was started at 10 december 2008 upto 12 feb.2009,total 64 days of span. After the end of the experiment the final conc.of sample was reduced to 15900mg/ml to 10mg/ml in case of 1st flask .showing highest degree of degradation.
As mentioned above the focus on the degradation of the contaminated ground water by diesel, the sample are collected either directly from the contaminated site or by leaking underground diesel storage tank in restaurant. Samples were kept in 40c till it delivered to the lab.
LITERATURE SURVEY:
2.1) P.A.Vieira et al at 2007 studied the effects of fuel concentration (diesel and gasoline), nitrogen concentration and culture type on the biodegradation of TPH effluent similar to what was found at inland fuel distribution terminals. An experimental design with two levels and three variables (23) was used. The mixed cultures used in this study were obtained from lake with a history of petroleum contamination at brazil and were named culture C1 (collected fromsurface sediment) and C2 (collected from a depth of approximately 30 cm). Of the parameters studied, the ones that had the greatest influence on the removal of total petroleum hydrocarbons (TPH) were a nitrogen concentration of 550 mg/L and a fuel concentration of 4% (v/v) in the presenceof culture C1. The biodegradability study showed a TPH removal of 90±2% over a process period of 49 days. Analysis using gas chromatography identified 16 hydrocarbons. The aromatic compounds did not degrade as readily as the other hydrocarbons that were identified.[]
Technical correctness:
The main idea of the paper is ‘biodegradation of the petroleum oil using bacteria and nematodes’. Author has explained in a proper way how to collected and bacteria was used to carry out the experiment, also the main part is that he has used the nematodes as an bacteriofeedes to consume the bacteria which will degrade the oil. The graphs are good enough to explain the optimization and results of the exp in 64 days of time span.
CONCLUSION
As per the remediation concern about the petroleum hydrocarbons, other method like physical and chemical are also useful for the remediation of these. But they produce more toxic waste as compared to bioremediation. Bioremediation uses bacteria to convert the hazardous petroleum toxic into less toxic compounds, and produces waste which is also product of biological waste which can be degraded in nature easily also the bacterivore nematodes used as an feeder on these bacteria hence a food chain is developed which will help to minimize the biomass. So as compared to other methods the author method is very well useful.