Non-Radioactive Oily Wastewater Treatment Solution for Nuclear Power Plants
A newly built nuclear power plant generates a stream of non-radioactive oily production wastewater that requires purification. The wastewater mainly contains petroleum substances (from transformer oil, mechanical equipment lubricants, etc., with oil concentrations between 500 and 2000 mg/L) and suspended solids (about 100 mg/L). Both the influent quality and the flow rate fluctuate, and the oil content rises significantly under shock loads.
Non-radioactive oily wastewater from the nuclear island, the conventional island and other equipment is collected and conveyed to an equalization tank in the oily production wastewater treatment area. A lift pump then sends it to the oil–water separation unit for primary separation. The separated effluent flows into an intermediate buffer tank, from which a lift pump delivers it to precision filtration equipment for advanced treatment. Oily wastewater that meets the standard is discharged to the plant-wide production wastewater pipe network, with an emergency connection that can divert flow to a tank-type discharge monitoring tank; non-compliant effluent returns to the equalization tank for re-treatment. Waste oil separated from the water is routed to a storage tank for temporary holding. If the oil–water separation unit fails or the influent flow overloads the system and the liquid level in the equalization tank exceeds the alarm value, an emergency drainage pump starts automatically and discharges the wastewater to the production wastewater system. In addition, the small amount of sludge generated during treatment can be returned to the equalization tank and removed periodically by manual cleaning.
Process flow diagram of the pretreatment of non-radioactive oily production wastewater
According to the client's technical specification, the treated effluent must meet oil ≤ 1 mg/L and suspended solids ≤ 10 mg/L. To solve this purification problem, SINOKLE has combined its core technologies with rich project experience in a mature and reliable treatment train: pretreatment filter + KHC high-efficiency coalescing oil–water separator + CDOF ozone advanced catalytic oxidation unit.
Process flow of advanced treatment of non-radioactive oily production wastewater
After the pretreatment described above, the plant's oily wastewater first passes through the filtration units, which remove part of the suspended solids, and then enters the high-efficiency coalescing oil removal unit. The coalescing cartridges inside effectively aggregate emulsified oil droplets ranging from 0.1 to 20 micrometers, achieving thorough removal of emulsified oil and safeguarding effluent quality.
Site equipment of a highly emulsified oily wastewater treatment project
The coalescer effluent is boosted by an ozone dosing pump into the high-efficiency ozone injection and reaction unit. This reaction module combines ozone catalytic oxidation with dissolved-air flotation: residual organics are further oxidized and decomposed, while the converted insoluble matter is carried upward by microbubbles to form a scum layer that is removed at intervals. After multi-stage catalytic ozone oxidation, the oil concentration in the wastewater can be reduced to below 1 mg/L. The filter units are backwashed with hot water based on differential-pressure signals, and the backwash wastewater is discharged separately. The whole system operates fully automatically under PLC or DCS control, simple to operate and requiring little maintenance.
The unit is designed for a treatment capacity of 10 m³/h and mainly consists of one coalescing oil separator, two filter units and one CDOF ozone advanced catalytic oxidation device (including the CDOF reactor and an ozone generation skid). The system adopts a modular skid-mounted design with a compact layout covering only about 26 square meters. Successful operating experience from many similar projects at home and abroad shows that the scheme delivers stable and reliable effluent quality and can effectively handle extreme treatment demands under shock loads.
