In Canada, environmental issues caused by petroleum-contaminated sites are becoming a major concern. Therefore, effective physicochemical remediation technologies are desired for produced water treatment and groundwater remediation in oil fields. In this dissertation research, the feasibility of treating produced water using synthetic polymers combined with natural diatomite was evaluated. Using diatomite as an adsorbent and a coagulant aid, this study provided an economical and enhanced approach for utilizing diatomite in the clean-up of produced water. A pilot-scale electrocoagulation process was developed for enhanced removal of hardness, chemical oxygen demand, and turbidity to mitigate the scaling and fouling of Reverse Osmosis membranes. Response surface methodology was employed to refine operating parameters and to evaluate individual/interactive effects of parameters on pollutant recovery. The modification of palygorskite with gemini surfactants enhanced phenanthrene retention in solid particles from aqueous phase. The effects of solution chemistry on phenanthrene sorption to modified palygorskite were systematically studied. The effectiveness of gemini modified palygorskite as the novel remediation material in polycyclic aromatic hydrocarbon contaminated water remediation was revealed and examined. A multi-level fuzzy-factorial inference approach was proposed to elucidate the sorption behavior of phenanthrene on palygorskite modified with gemini surfactants. Fuzzy vertex analysis discretized the design factors with triangular membership functions into multiple deterministic levels. Examination of curvature effects of factors revealed the nonlinear complexity inherent in the sorption process. The potential interactions among experimental factors were detected, which was meaningful for providing a deep insight into the sorption mechanisms under the influences of factors at different levels. The enhancement of soil retention for phenanthrene was investigated through the sorption barriers created by binary mixture of cationic gemini and nonionic surfactants. The research addressed the sorption characteristic and mechanism of gemini surfactant in complex soil system using a developed Two-step Adsorption and Partition Model. The sorption barrier substantially enhanced the soil retention capabilities for phenanthrene, while the sorption of gemini was inhibited by the increasing nonionic surfactant dose. The interactions among water, soil, surfactant, and contaminant in petroleumcontaminated systems have been revealed. This research can provide reference on the implementation of remediation technologies at petroleum-contaminated sites.