Date of Award
Master of Science in Environmental Science - (M.S.)
Chemical Engineering, Chemistry and Environmental Science
John R. Schuring
Richard B. Trattner
Pilot plant studies have been carried out on a process for the remediation of soils contaminated with volatile organics (VOCs) and semi-volatile organics (SVOCs) by microwave-assisted steam distillation that had been developed in benchscale studies. The major concern had been that the process is based upon the use of electrical energy, and thus could not be competitive with fossil fuel based technologies like incineration. That concern was addressed in the pilot plant studies.
A pilot plant rated at 6 kW power and a cavity of approximately 60 cubic feet was used. In studies carried out on a water load it was found that the incident power was 4.3 kW. In those studies, the distribution of energy within the cavity was also studied.
Substrates studied were sand and soil, respectively. The total weights of the subtrates were in the 40-50 lb range. The substrates were impregnated with naphthalene. It was found that the remediation costs were of the order of $4/ton to effect 100% remediation. Even if total power operating costs are taken into consideration, the cost is less than $15/ton. That's an exceedingly low number. For incineration, costs are in the $200-$300/ton range, plus the ash problem and the public's dislike of incineration processes.
The costs obtained in this study cannot be considered as a basis for making comparisons to existing processes. Comparable costs can only be obtained from field testing, now in the planning stage. Their significance is that it does not appear to be the case that the microwave process is prohibitively expensive because of the cost of electric power.
Other studies in the thesis related to analytical procedures: it was concluded that ultrasonic extraction was preferrable to Soxhlet extraction; also, normal needle injection into the GC/MS was as effective as hot needle injection.
Lu, Yongping, "Microwave treatment of hazardous wastes : feasibility studies - Operating costs" (1992). Theses. 2317.