From Deoiling to Advanced Purification: How SINOKLE's Combined Technologies Treat Complex Wastewater

In industrial wastewater treatment, water quality varies greatly from one project site to another. Some wastewater is dominated by high oil content and severe emulsification, some is characterized mainly by COD, chromaticity and odor, while others are polluted simultaneously by oil, suspended solids, colloids and refractory organics. Faced with complex water quality, a single piece of equipment can often address only a partial problem and hardly delivers long-term stable treatment performance. By combining coalescing deoiling, CDFU swirl dissolved-air flotation, the integrated CDOF ozone advanced-oxidation flotation unit, KFM activated-media filtration and KHC high-efficiency coalescing deoiling, SINOKLE has developed systematic treatment solutions tailored to different scenarios.

For wastewater with high oil content and severe emulsification, the priority is to rapidly reduce the oil concentration and relieve the load on downstream systems. SINOKLE typically adopts the combined process of 'coalescing deoiler + CDFU' or 'high-efficiency coalescing deoiler + two-stage CDFU'. The coalescing deoiler first promotes the collision, coalescence and growth of tiny oil droplets to achieve front-end oil–water pre-separation; the CDFU then uses swirl separation, micro-nano bubble flotation and coalescing demulsification to enhance the removal of fine oil droplets, emulsified oil and suspended solids. Taking a desalter and tank-farm oily-water treatment project of a petrochemical plant in Xinjiang as an example, the influent oil content was ≤20,000 ppm; after treatment with 'high-efficiency coalescing deoiler + two-stage CDFU', the effluent oil content was ≤150 ppm and the oil-in-water rate was ≤30%, achieving a substantial reduction and separation of the high-oil wastewater.

For extremely high-oil acidic water, relying solely on flotation or oil separation can hardly achieve stable and deep deoiling. SINOKLE adopts the combined route of 'CDFU + KHC high-efficiency coalescing deoiler': the CDFU first removes most floating oil, dispersed oil and suspended solids, and the KHC then performs deep coalescing separation of fine emulsified oil. In a coking acidic-water project of a Sinopec petrochemical plant in Henan, the influent oil content was ≤150,000 ppm; after treatment with 'CDFU + KHC high-efficiency coalescing deoiler', the effluent oil content was ≤100 ppm, demonstrating the deep deoiling capability of this combined process for high-concentration, highly emulsified acidic oily wastewater.

For composite-polluted wastewater such as oilfield produced water, fracturing flowback fluid and drilling waste liquid, the treatment objective is not only deoiling but also reducing turbidity, SS, iron ions and some refractory pollutants. SINOKLE adopts the combined process of 'CDFU + CDOF + KFM': the front-end CDFU handles deoiling and suspended-solids removal, the mid-stage CDOF performs ozone multi-catalytic oxidation, and the back-end KFM provides further filtration to ensure stable effluent. Taking the Jiayou oilfield project in Congo (Brazzaville), Africa as an example, the feed consisted of gathering-station wastewater, flowback fluid and drilling waste liquid, with a treatment capacity of 4,600 m³/d. After adopting 'CDFU + CDOF + KFM', the effluent met the marine-discharge standard, with petroleum ≤0.5 ppm, turbidity ≤3 NFU, SS ≤3 mg/L and iron ≤0.15 mg/L.

For terminal fine filtration and effluent assurance, the KFM activated-media filter mainly plays a 'stable final safeguard' role. The media, modified to be super-hydrophilic, features high filtration precision, low resistance, strong anti-fouling capability, easy cleaning and long service life. Under the conditions of influent oil content ≤50 ppm and SS ≤50 mg/L, the KFM filter outlet can reach oil content ≤6 ppm, SS ≤2 mg/L and median particle size ≤1.5 μm. It is suitable for oilfield produced water, refinery and chemical wastewater and other scenarios that require further reduction of oil and suspended solids.

For wastewater with prominent COD, chromaticity and odor problems, the integrated CDOF ozone advanced-oxidation flotation unit plays a core role. This technology organically combines ozone advanced oxidation, swirl-enhanced mass transfer, dissolved-air flotation and catalytic oxidation, and can be used for refractory organic removal, decolorization, deodorization and standard-upgrading retrofit. Compared with traditional single ozone oxidation, the CDOF places more emphasis on ozone utilization and reaction efficiency, and improves COD reduction and effluent stability through a closed pressurized reaction and a multi-catalytic system. The presentation material also clearly states that the CDOF can efficiently remove COD, suspended solids, colloids, bacteria, viruses and other pollutants, and can be used for pretreatment or advanced treatment of landfill leachate, refining, metallurgy and pharmaceutical wastewater.

From the perspective of different treatment objectives, the application logic of SINOKLE's combined technology is very clear: when wastewater is dominated by high oil content, coalescing deoiling and the CDFU are used to rapidly reduce oil; when the wastewater is highly emulsified and extremely concentrated in oil, the KHC is added to achieve deep coalescing separation; when the wastewater contains oil and suspended solids together with refractory pollutants, 'CDFU + CDOF + KFM' is used to realize the synergy of deoiling, oxidation and filtration; when the effluent needs further refined assurance, the KFM serves as the terminal stabilizing unit; and when COD, chromaticity and odor become the core problems, the CDOF undertakes the deep oxidation role.

Overall, SINOKLE's combined technology is not a simple stacking of equipment, but determines the process sequence according to pollutant forms and treatment objectives, forming a treatment system of 'front-end load reduction, mid-stage intensification and back-end assurance'. Through the synergy of different technical units, multiple indicators such as oil, suspended solids, COD, chromaticity and odor can be improved simultaneously, providing stable, efficient and green systematic solutions for petroleum refining, oilfield development, landfill leachate, power-plant oily wastewater and other difficult industrial wastewater treatment.