Heavy oil wastewater treatment system and method

The invention relates to the field of wastewater energy-saving environmentally-friendly treatment technology, especially to a heavy oil wastewater treatment system and a method. The system comprises an oil extraction device, an oil-water separator, a deep pretreatment device, a multiple-effect evaporation and MVR evaporation device and a salt drying device, which are successively connected. An oil-water mixture extracted by the oil extraction device passes through the oil-water separator to separate out oil; heavy oil wastewater undergoes deep pretreatment to remove impurities and oil in the wastewater is further recovered; single-phase wastewater which has undergone deep pretreatment enters the multiple-effect evaporation and MVR evaporation device to undergo evaporation and concentration, and secondary steam generated by the evaporation passes through a vapor compressor to raise caloric content and is used as the hot resource for evaporation of the system to save energy by more than80% and save water by mor