The Effects of Chicken Manure Digestates on the Removal of Diesel Range Organics from Petroleum Products Polluted Soils

This study was designed to investigate the efficiency of using locally produced chicken manure digestates (CMD) as nutrient supplement for the removal of diesel range organics (DRO) from petroleum products polluted soils by land farming process. Soils samples spiked with hydrocarbon mixture (HCM), 5 % and 10 %) were treated with three rates of the CMD (0, 10 or 20 %) for a 336 days period. Soil samples were collected at day 1, 14, 28, 56, 84, 168 and 336 time interval and the samples were extracted using standard methods. The concentrations of DRO at various sampling periods were determined using a gas chromatography equipped with a flame ionization detector (GC – FID). The percentage removal of the DRO and the significance differences of the different treatments were evaluated using statistical tools. Results obtained showed that the use of 10 and 20 % CMD led to the removal of about 50 and 58 % of the DRO respectively from the 5 % HCM polluted soils and about 41 and 35 % respectively for the 10 % HCM polluted samples at day 56 and by day 84, the percentage removal of the DRO increased to about 60, 76 and about 46, 52 respectively using the two rates of treatments; in the 5 and 10 % HCM polluted samples respectively. These values were reasonable considering the level and toxicity of HCM pollution. Significant differences (P < 0.05) between the treatments and the various control samples were observed in the removal of the DRO from day 56 to 168. And at the end of 336 days, the 10 and 20 % CMD treatments enhanced the removal of about 81, 96 and 56, 67 % from the 5 and 10 % HCM polluted soils respectively but no significant differences were observed between the control and the treatment samples particularly in the 10 % HCM polluted soils at this date. This study has revealed that: the use of chicken manure digestates could facilitate the removal of reasonable proportion of DRO in a short remediation time of 56 days from high and toxic petroleum polluted soils. The efficacy of the CMD was observed to decrease as the remediation period increased. It was also observed that 10 % CMD treatment was optimal for the removal of DRO at a short remediation period and repeated application of the nutrient supplement would be required if remediation period exceeded 56 days. Furthermore, it could be concluded that CMD is an effective inoculant and nutrient supplement during