New Technologies for the Treatment of Coking Acidic Wastewater

Treating highly emulsified, highly acidic coking wastewater has long been a challenging issue in the petroleum refining industry. In particular, the acidic wastewater generated during the coking process is characterized by extremely complex composition and very high pollutant concentrations, with the following specific features:

· High content of coke fines with very small particle size;

· High oil content, with fine oil droplets and a high degree of emulsification;

· High concentrations of sulfur compounds, ammonia nitrogen, and phenolic substances;

· Highly variable composition with large fluctuations in pollutant concentrations.

If such wastewater is sent directly to the stripping tower without proper pretreatment, it can not only cause equipment blockage and reduce stripping efficiency and liquid ammonia quality, but in severe cases may also lead to unplanned shutdowns, resulting in significant economic losses. These problems pose serious challenges not only to the coking wastewater treatment process but also to environmental protection and sustainable development. Therefore, effective treatment of coking acidic wastewater is crucial to improving the stability and reliability of downstream treatment units. 

Traditionally, this type of wastewater has been treated using chemical dosing methods. However, these approaches suffer from drawbacks such as large chemical consumption, generation of substantial amounts of scum and oily sludge, unstable treatment performance, and the potential risk of secondary pollution. 

To address this challenge, after extensive research and practical application, the Shenzhen Clear Science & Technology Co., Ltd (SINOKLE) has innovatively developed a coking acidic wastewater treatment system centered on CDFU cyclonic dissolved air flotation, fine filters, and the KHC high-efficiency coalescing oil remover. This system adopts a purely physical demulsification and separation process, requiring no chemical additives. 

The wastewater first passes through a coarse filter to remove large particulate impurities, then enters the CDFU cyclonic dissolved air flotation unit, where suspended solids and emulsified oil are efficiently separated through the combined action of swirling flow and dissolved gas. The wastewater then flows through a fine filter to further remove solid particles and residual emulsified oil. Finally, deep purification is achieved in the KHC high-efficiency coalescing oil remover, which thoroughly removes fine oil droplets and remaining suspended solids. The treated effluent is clear and transparent, with an oil removal efficiency exceeding 99%. 

Compared with traditional chemical treatment methods, this coking acidic wastewater treatment system offers the following significant advantages: 

· No chemical additives required, eliminating problems associated with high chemical consumption and the generation of scum and oily sludge, thereby fundamentally avoiding secondary pollution risks;

· A purely physical treatment process that is stable and highly efficient, with excellent demulsification performance and effective separation of emulsified oil and suspended solids;

· High-quality recovered oil with low water content, suitable for re-refining, achieving resource conservation and economic benefits;

· Fully automated, enclosed, pressurized operation, ensuring operational safety and no environmental risk;

· Small footprint and low operating cost.

Application Case

A coking acidic wastewater treatment system customized by the SINOKLE for a petrochemical enterprise in Luoyang, China, has been successfully put into operation. The influent oil content of the system was as high as 15% (150,000 ppm). After treatment, the effluent quality remained stable, with the average oil content reduced to below 50 ppm, achieving an oil removal efficiency of over 99%. This successfully resolved the long-standing acidic wastewater treatment challenges faced by the enterprise. 

Pic.1 On-site view of the coking acidic wastewater treatment project

Pic.2 Treatment performance of coking acidic wastewater (left: influent; right: effluent)

The successful implementation of this project not only provides an effective solution for treating highly emulsified acidic coking wastewater, but also marks a major breakthrough in coking wastewater treatment technology, offering strong support for the sustainable development of petrochemical enterprises and the green development of the petrochemical industry.