Optimization and Application of Ship Oily Wastewater Treatment Processes
Ship oily wastewater is wastewater generated during ship operation that contains grease, fuel residues, lubricating oil and other pollutants, mainly originating from engine rooms and cargo holds, and covering oily tank washing water, engine room oily water and oily ballast water. Its composition is complex, including hydrocarbon residues and solid particles from fuel combustion, lubricating oils from various mechanical equipment, and edible oils and paints generated during operation; it is generally severely emulsified, so traditional oil interception and gravity sedimentation processes struggle to meet standards, while chemical treatment produces large amounts of hazardous waste and treatment costs are high.
To solve this problem, SINOKLE adopted a pure physical treatment solution centered on its CDFU (Cyclonic Dissolved Gas Flotation Unit), which organically integrates cyclonic centrifugal separation, a new generation of dissolved air technology and high-efficiency flotation, using micro-nano bubbles to achieve efficient demulsification and oil removal and stable discharge up to standard. Thanks to its specially designed flotation method, the technology greatly improves flotation efficiency, shortens residence time, and achieves rapid removal of oil and suspended solids.
CDFUThe process has significant advantages:
First, pure physical demulsification and separation, with high and reliably stable oil removal efficiency; the recovered waste oil creates economic benefits, with no secondary pollution and no oily hazardous waste generated;
Second, the amount of scum is reduced by more than 1/3, lowering secondary treatment costs;
Third, closed operation under pressure, with no hydrogen sulfide or oil vapor leakage, ensuring a safe and friendly site environment;
Fourth, single-stage residence time of less than 5 minutes, small footprint, fully automatic operation, easy operation and maintenance, short construction period, and possible online implementation; fifth, strong shock resistance, able to adapt to large water quality fluctuations.
In terms of the treatment process, ship oily wastewater passes through two-stage CDFU oil removal: under the swirl action in the tank, the wastewater fully contacts the ultrafine bubbles generated by dissolved air; pollutants are attached, demulsified and aggregated, then float up and are discharged to the waste oil collection tank, while waste residue enters the sludge pit. Under normal water quality, neither stage needs flocculant; when emulsification is severe, only the second stage adds a small amount of flocculant as appropriate. The second-stage effluent enters the downstream process after being tested up to standard by an oil-in-water analyzer; nitrogen is used for gas injection in both stages, and the tail gas is treated by a tail gas destruct unit before discharge, ensuring stable and compliant treatment results.
The entire system uses PLC or DCS fully automatic control; closed operation under pressure involves no safety or environmental risks. The dissolved air pump supports automatic and manual start modes and is equipped with automatic protection programs; effluent, oil discharge, exhaust and other stages are all automatically regulated, making operation and maintenance convenient.
A project example at a port in Guangdong with a treatment capacity of 60 m3/h shows that the complete set of equipment is integrated on one skid containing two CDFU reaction tanks and one stabilization tank, covering a total area of only 30 m2. The influent oil content and suspended solids were both about 1000 mg/L; after two-stage CDFU treatment, the oil content dropped below 30 mg/L and the suspended solids below 60 mg/L; after subsequent downstream treatment, compliant discharge was achieved, verifying the efficiency and practicality of this process.
