SUNYu,LIUYa-dan,GUChao,et al.Ultrasonic Sedimentation-Air Flotation-Microfluidic Filtration for Pretreatment of Machine Maintenance Flushing Wastewater：Performance and Removal Mechanism[J].China Water & Wastewater,2025,41(13):18-25.
Ultrasonic Sedimentation-Air Flotation-Microfluidic Filtration for Pretreatment of Machine Maintenance Flushing Wastewater：Performance and Removal Mechanism
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第41卷
Number:
第13期
Page:
18-25
Column:
Date of publication:
2025-07-01
- Keywords:
- machine maintenance flushing wastewater; ultrasonic pretreatment; air flotation; microfluidic filtration; oil content; iron; turbidity
- Abstract:
- The water quality of machine maintenance flushing wastewater fluctuates greatly, with oil content of up to 103.2 mg/L, iron content of 3.5 mg/L, turbidity of 800 NTU, and COD of 10 706 mg/L.Single air flotation cannot effectively remove these pollutants, resulting in deaths of a large number of acitivated sludge in subsequent biochemical tanks. This study proposed a combined process of ultrasonic sedimentation,air flotation, and microfluidic filtration as a pretreatment strategy for subsequent biochemical processes. The results showed that ultrasonic precipitation achieved a turbidity removal rate of 89.45% through acoustic agglomeration. Adding 25% hypochlorite to air flotation could oxidize and destroys the “water in oil” structure, resulting in a removal of 53.74% for oil. At the same time, Fe2+ was oxidized to Fe3+，and form Fe(OH)3 precipitate, with an iron removal of 89.73%. Microfluidic filtration utilized electrode electrolysis to produce more insoluble flocs, with COD sedimentation removal reaching 68.05%. During long?term operation, the iron content, oil content, and turbidity decreased by 96.3%, 92.5%, and 98.5% respectively compared to before the transformation, and the BOD5/COD increased from 0.15 to 0.40. The overall effluent quality of the sewage treatment plant met the requirements for washing water in the Reuse of Urban Recycling Water—Water Quality Standard for Industrial Uses (GB/T 19923-2005). The total investment for pretreatment was 1.31 million yuan, and the treatment cost was 3.80 yuan/m3, which was 41% lower than before. The development of this process provides a new technological approach for the biochemical pretreatment of machine maintenance flushing wastewater.
Last Update:
2025-07-01