A cleaner production process was used to recycle oily sludge generated from spent oil treatment industry. Due to its contents of residual oil and Fe-containing minerals, it can be converted into fuel oil and mesoporous magnetic carbon composite with specific surface area of over 150 m2/g under the proper thermal activation. The innovative technology focused on producing magnetic carbon composite which can be easily separated and recovered when using as an adsorbent.A cleaner production process was used to recycle oily sludge generated from spent oil treatment industry. Due to its contents of residual oil and Fe-containing minerals, it can be converted into fuel oil and mesoporous magnetic carbon composite with specific surface area of over 150 m2/g under the proper thermal activation. The innovative technology focused on producing magnetic carbon composite which can be easily separated and recovered when using as an adsorbent. The resulting carbon composite can be also used as catalyst or support for catalyst as a result of mesoporous structure. In addition, the recovered oil can be reused as an auxiliary fuel because of its high calorific value of about 10,000 kcal/kg.1. Environmental protection industry：wastewater treatment by adsorption (reused as an adsorbent).
2. Chemical process industry：catalyst or support for catalyst.
3. Refinery ：bottom sludge recycling treatment (petroleum oil tank).
4. Green energy industry：regenerated fuel oil by separative recovery.