Performance of Organic and Inorganic Substrates for the Bioremediation of Crude Petroleum Hydrocarbon Polluted Soil

Abstract

This paper presents an evaluation of the performance of dead cells
microorganism such as yeast, organic substrate such as poultry manure,
decayed domestic waste manure and inorganic substrate such as N.P.K
fertilizer in the bioremediation of petroleum hydrocarbon polluted soil.
Hydrocarbon polluted soil was simulated on a laboratory scale and
characterized to determine the particle size distribution, pH, moisture
content, total organic carbon, total nitrogen and total hydrocarbon
content. For effective treatment, 2:1 mixture (w/w) of the polluted soil
and the treatment substrate in addition to 25ml of nutrient agar was
utilized. The entire experiment was monitored for a period of twelve (12)
weeks and triplicate samples were collected from each setup on a weekly
basis and analyzed using ultra violet spectrophotometer in order to
determine the residual hydrocarbon content. The amount of
hydrocarbon removed per time coupled with the efficiency of
remediation was then computed using simple mass balance equation.
Results obtained revealed a gradual decrease in the total nitrogen
content (TNC), total organic carbon (TOC) and total hydrocarbon
content (THC) with remediation time. This decrease in TNC, TOC and
THC was also observed to vary with the type of substrate as follows. For
yeast; TOC reduces from 2.169 to 0.16g/kg, TNC reduces from 5.20 to
1.53g/kg, and THC reduces from 11.533 to 3.18mg/l. For poultry
manure; TOC reduces from 2.169 to 0.14g/kg, TNC reduces from 5.20
to 1.76g/kg, and THC reduces from 11.533 to 3.54mg/l. For NPK; TOC
reduces from 2.169 to 0.11g/kg, TNC reduces from 5.20 to 2.43g/kg, and
THC reduces from 11.533 to 2.02mg/l. For decomposed waste; TOC
reduces from 2.169 to 0.98g/kg, TNC reduces from 5.20 to 2.08g/kg, and
THC reduces from 11.533 to 9.17mg/l. The gradual decrease in TNC,
TOC and THC was attributed to the fact that; as the microorganism
utilizes the available nitrogen and organic carbon present in the soil and
increase in population; they again react with and break down the
petroleum hydrocarbon