This paper presents the development of a modified Biopile system that was used for the treatment and disposal of TPH-contaminated sludge.Over the course of 30 yr, highly contaminated sludge had accumulated in a sedimentation pond, which formed part of a petrochem. plant's storm and wastewater treatment process.Chem. analyses showed that the TPH content was as high as 330,000 ppm and was therefore considered a hazardous material.Biol. analyses of the sludge showed the presence of a viable microflora in sufficient concentrations to sustain a biol. treatment process.The objective was to modify Biogenie's Biopile process (normally used to treat contaminated soil) in order to biol. reduce the TPH content of the sludge <30,000 ppm to allow for its disposal in a sanitary landfill.Laboratory work was conducted to develop a successful approach to give the sludge the appropriate structure to carry-on biodegradation activities using the Biopile process.Different types of bulking agents were evaluated for their capacity to absorb excess water and facilitate aeration.Following this initial development step, different laboratory scale treatment conditions were also studied in an engineered mesocosm system to simulate the full-scale process.The water content, type and quantity of nutrient sources, as well as the aeration rate were evaluated.Different process simulations were then conducted.Physico-chem. and biol. parameters were monitored during treatment.An optimized laboratory scale treatment process was able to decrease the average concentration of the tested material from 190,000 to 17,000 ppm within a 23-wk treatment period representing a degradation efficiency of 91%.The microbial count during treatment reached concentrations as high as 109 CFU/g and the temperature increased ≤46°.During this bench-scale phase, re-engineering of the Biopile process was also conducted to accommodate modifications and constraints that had been created.Based on laboratory results, Biogenie proposed a guaranteed remedial solution using a modified Biopile process.Overall, 7800 tons of contaminated material, ranging in consistency from liquid to solid, was treated.The material was placed in 2 Biopiles and treated over a 6-mo period, which included the Canadian winter season.During treatment, the gaseous effluent was treated in a biofilter.Attention was paid to avoid excessive loss of water from the Biopile that may have impaired the biol. process.Monitoring of physico-chem. and biol. parameters during treatment showed consistency with what was observed during the laboratory study.Total microflora reached a concentration ≤109 CFU/g and ≤23% were TPH degraders.Average temperature was ∼43°.All other physico-chem. parameters were maintained at the appropriate range for biol. treatment.Using this modified Biopile system, the TPH content of this hazardous material was reduced below the target criteria of 30,000 ppm and was no longer considered hazardous.The treated material was then disposed of in a sanitary landfill.In the context of the soon to be enforced European Landfill Directive (LD), which will require the treatment of hazardous waste prior to landfilling, the implementation of this project demonstrates the capability of biol. treatment to cost-effectively meet some of the new treatment requirements.
