Petrochemical wastewater refers to the effluent discharged from petrochemical production facilities. Characterized by large volumes, it encompasses not only process wastewater but also cooling water and other water streams involved in production operations. Its composition is highly complex, a consequence of the diverse range of petrochemical products and the intricate nature of associated reaction processes and unit operations, which directly contribute to the variable and complex properties of the wastewater. This paper, in collaboration with manufacturers of online water quality monitoring instruments, examines the key monitoring targets for petrochemical plant wastewater.
Primary Monitoring Points in Petrochemical Plants
Monitoring points within petrochemical plants typically include the total wastewater discharge outlet, workshop/production facility wastewater discharge outlets, and stormwater discharge outlets. For facilities subject to the discharge standards specified in *GB 31571* (Note: The original “GB 31571D” may be a typo; the official standard is GB 31571-2015 *Emission Standard of Pollutants for Petroleum Chemical Industry*), the core wastewater monitoring targets must be determined based on factors such as raw material types and production processes. A breakdown by discharge outlet is as follows:
1.Total Wastewater Discharge Outlet
Key parameters to monitor include:
– Organic contaminants: Total Organic Carbon (TOC), oil content;
– Nutrients: Total phosphorus (TP), total nitrogen (TN);
– Inorganic pollutants: pH value, total cyanide;
– Heavy metals: Total copper (Cu), total zinc (Zn), etc.
2.Workshop/Production Facility Discharge Outlets
Monitoring focuses primarily on heavy metal pollutants, including:
Total mercury (Hg), total chromium (Cr), hexavalent chromium (Cr⁶⁺), total lead (Pb), total cadmium (Cd), and total arsenic (As).
3.Stormwater Discharge Outlet
Core monitoring targets are:
Chemical Oxygen Demand (COD), ammonia nitrogen (NH₃-N), pH value, and petroleum hydrocarbons.
Conclusion
Pollutant indicators for wastewater monitoring vary across industries and water quality types. Thus, the selection of monitoring targets must be tailored to the specific characteristics of the wastewater in question.
