Date of Award

5-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Dr. Ali AI-Marzouqi

Second Advisor

Dr. MD Monwar Hossain, PhD

Third Advisor

Dr. Mohamed A. AI Nakoua, PhD

Abstract

The treatment and disposal of oil sludge represents major challenges for oil industries and municipalities. The oil sludge consumes high portion of oil industries' budget. Several destruction and conventional technologies such as incineration, landfill and biological treatment have been used to treat oil sludge. However, most of these technologies have not been commercially practical due to some limitations including efficiency, ease of operation and cost or not being friendly to the environment.

Supercritical Water Oxidation (SCWO) provides a powerful means to transform toxic organic materials into simple, relatively inert oxides. In this thesis, treatment of oil sludge by using SCWO was performed in a micro reactor via a continuous process system at reaction temperatures between 340-460°C and pressures between 200-300 bar in which 340°C and 200 bar are points near the critical point of water, flow rates between 1-5 ml/min, which indicates reaction times between 2-10 minutes. The effect of operating conditions namely temperature, pressure, flow rate/residence time of the reaction, excess oxygen (O2) and initial concentration of oil sludge in the sample were investigated to evaluate their influence on Total Organic Carbon (TOC) removal rate and find out an optimal operating conditions for such process.

The results revealed that 99.6% removal rate of TOC can be achieved at both supercritical conditions and near the critical point of water. TOC removal rate remained constant with increase of all above examined parameters at both supercritical conditions and near the critical point of water. This can be attributed to the nature and complexity of the oil sludge sample, instantaneous nature of the reaction at both supercritical conditions and near the critical point of water and separation of feedstock during injection process. Moreover, the counterbalancing effect of different properties on SCW and complete oxidation of oil sludge have also contributed to the insignificant variation on TOC removal.

Carbon Dioxide (CO2) was the main carbon product of both reactions of supercritical and near the critical point with very small amounts of inorganic carbon species dissolved in the liquid effluent. Similar to TOC removal rate, all the parameters studied had no considerable effect on CO and CO2 yields at both conditions. The peak amount of 99.4% of CO2 and 0% of CO yields were achieved.

Hence, SCWO can be considered as an alternative environmentally attractive technology with a unique characteristic that can be utilized for the complete destruction of oil sludge. Even though operating conditions of the process near the critical point of water will lead to desired results. The thesis also includes some suggestions for further research to continue the development of this technology and consolidate the process at industrial scale.

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