Use of wastewater sludge for the amendment of crude oil bioremediation in meso-scale beach simulating tanks

We investigated the effects of the application of wastewater sludges on mic robial degradation of crude oil. The experiments were carried out in four b each simulating tanks. In each tank, filled with gravel and seawater, crude oil was added on the surface of seawater. Dehydrated-wastewater sludge, li quid-wastewater sludge and synthetic fertilizers were added in tanks A, D a nd C, respectively. In tanks A and D, sharp increases in the bacterial numb er and the oxygen consumption occurred immediately while the increases in t ank C was slower. The concentration of nitrogen was high during first few w eeks and later decreased in tanks A and D. The synthetic nitrogen fertilize r was maintaining the nitrogen concentration above 1 mg l(-1) for the whole experimental period. These observations indicated that the effect of the s ynthetic nitrogen fertilizer was more enduring than those of the liquid and dehydrated sludges. However, higher concentrations of phosphorous were sup plied by both the liquid and dehydrated sludges than by the synthetic phosp horous fertilizer. No significant differences were observed between the bio degradation rates of crude oil in each amended tank. Thus, it was concluded that the wastewater sludges are useful as fertilizers for crude oil biorem ediation.