Matching Units to the Pollutant: How SINOKLE Assembles Treatment Trains for Hard Wastewater
Across petroleum refining, oilfield development, new energy, chemicals and power generation, the complaints repeat with weary consistency: oil that spikes without warning, emulsions that refuse to break, suspended solids too fine to settle, COD that will not come down, odour at the fence line, and a feed that swings hour to hour. Conventional trains were never designed for that combination. They leave oil behind, burn through chemicals, generate sludge that has to be manifested as hazardous waste, eat land most retrofit sites do not have, and lose stability the moment the influent shifts. The question that matters to an operator is narrower than it sounds: which route keeps its performance over a long cycle without turning the utility block into a chemical warehouse.
Read the water before you choose the hardware
SINOKLE approaches the problem by splitting it into duties rather than products. Oil removal, demulsification, COD reduction, suspended-solids capture, decolorization and deodorization are treated as separate jobs, and each job gets a unit built for it. Around those duties sits a family of core equipment: CDFU, the cyclonic dissolved-air flotation (CDFU) machine; the CDOF integrated ozone advanced oxidation dissolved-air flotation unit; the KFM modified-media filter; the coalescing pressure oil remover; and the coalescing oil-water separator. What leaves the shop is rarely one vessel. It is a configured train set against the water analysis, the discharge permit and the plot that happens to be free.
Where CDFU earns its keep
On oily streams, CDFU does the heavy lifting. One shell packs cyclonic centrifugal separation, dissolved-air flotation, micro-nano bubbles and coalescing separation into a single pressure vessel. Cyclonic action supplies the separating force, micro-nano bubbles go after the fine droplets and suspended particles that gravity alone will never catch, and the coalescence stage breaks and regrows emulsified oil until it separates. Waste oil, emulsified oil and suspended solids leave together, quickly. Against conventional dissolved-air flotation the trade-offs are short retention time, small footprint, high automation and strong shock-load tolerance, which is why it shows up on electric-desalting wastewater, crude-oil tank-farm cut water, coking acid water, oilfield produced water and fracturing flowback fluid.
When oxidation has to enter the chain
Organics that neither float nor settle need a different tool. The CDOF integrated ozone advanced oxidation dissolved-air flotation unit folds ozone advanced oxidation, homogeneous and heterogeneous catalytic oxidation, hydraulic cavitation, cyclonic enhanced mass transfer and flotation separation into one machine. Ozone mass transfer and oxidation efficiency both rise, and COD, chroma, odour, colloids and bacteria are removed in the same pass. Traditional ozonation is slow, wastes ozone and costs money to run; sealed pressurized operation, multiple catalytic reactions and automatic control are what make the CDOF version safe, steady and affordable.
What the projects actually looked like
The Congo-Brazzaville oilfield produced-water and fracturing-flowback-fluid project is the clearest example of the combined logic. Oilfield produced water and flowback fluid arrive carrying oil, suspended solids and refractory organics at the same time, so SINOKLE ran a CDFU + CDOF + KFM chain: high-efficiency oil removal first, enhanced oxidation second, filtration as the guarantee. Phase I was built at 4500 m3, and Phase II took the installation to 6500 m3. For a remote site with difficult logistics, that is a statement about integration capability as much as about equipment.
In refining, electric-desalting wastewater and crude-oil tank-farm cut water are the classic high-oil, high-emulsion, high-variance streams. The mature answer there is a coalescing oil remover ahead of CDFU: the coalescer knocks out free and dispersed oil at the front end and unloads the downstream unit, then CDFU deals with fine droplets, emulsified oil and suspended solids. That pairing has been installed at Sichuan Petrochemical for crude-tank-farm wastewater, at Urumqi Petrochemical for refinery electric-desalting and tank-farm water, at Hongrun Petrochemical for electric-desalting wastewater, and as an oil-removal skid on the CNPC Yunnan Petrochemical atmospheric-vacuum unit electric-desalting drain. Repeatability across that many sites is the point.
At Xinjiang Dushanzi Petrochemical, a two-stage CDFU arrangement was used instead. Electric-desalting cut water is heavily emulsified and full of fine particles, and single-pass flotation drifts; staging the cyclonic dissolved-air flotation restores separation and gives the system room to absorb feed swings. Landfill leachate is a different animal again, with high COD, deep colour, obvious odour and poor biodegradability. The Hubei Shiyan leachate advanced-treatment project used CDOF, leaning on multiple catalytic ozone oxidation and enhanced mass transfer to strip refractory organics, colour and smell so the downstream step has something it can actually handle.
Where the logic ends up
None of these installations hinges on a single machine. Highly oily water gets front-end coalescing plus cyclonic flotation; water carrying both oil and heavy suspended solids adds KFM modified-media filtration; streams dominated by COD, colour, odour and refractory organics bring in CDOF. Different units, clear jobs, one chain from pre-treatment to advanced treatment. As the sector pushes toward steadier operation, lower carbon, fewer chemicals, less sludge and smarter control, that kind of modularity is what lets a plant change one stage without rebuilding the whole train.