Brief Introduction

       It mainly includes three aspects: petroleum extraction wastewater, oil refining wastewater and petrochemical wastewater. Crude oil extracted from the oil field is discharged from the oily wastewater during the dehydration process. This wastewater also contains a large amount of dissolved salts, and its specific composition is related to the geological conditions of the oil-bearing formation.

       The wastewater discharged from the refinery is mainly oil-containing wastewater, sulfur-containing wastewater and alkali-containing wastewater. Oil-containing wastewater is the largest type of wastewater in an oil refinery. It mainly contains petroleum and contains a certain amount of phenol, acetone, aromatic hydrocarbons, etc.; sulfur-containing wastewater has a strong odor and is corrosive to equipment; alkali-containing wastewater mainly contains sodium hydroxide , And often entrain a large amount of oil and a considerable amount of phenol and sulfur, and the pH can reach 11-14. 

       The composition of petrochemical wastewater is complex. The wastewater from the cracking process is basically the same as the refinery wastewater. In addition to oil, some intermediate products may be mixed in, sometimes containing cyanide. Due to the variety of products and different processes, the composition of wastewater is extremely complex. The general characteristics are less suspended matter, more soluble or opacifying organic matter, often containing oil and toxic substances, sometimes also containing impurities such as sulfide