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This thesis aims to explore the current domestic steel industry wastewater recycling process, the various components contained in the wastewater, the impact on the wastewater recycling equipment currently used, and explore the corresponding treatment methods; through the field data collection, step by step to determine the problem that the system needs to improve.
The composition of recovered wastewater is complex. The hardness of sulfate and calcium and magnesium is generally high. The concentration of ammonia nitrogen in water will affect the formation of free residual chlorine. The growth control of biological bacteria is unstable. When the upstream wastewater treatment is abnormal, there will have a problem of excessive iron and manganese ions, resulting in rapid membrane clogging.
The improvement of source water quality can delay the loss of membrane, eliminate the problem of excessive iron and manganese ions, and slow down the membrane blockage. At the same time, through effective cleaning mechanism, it ensures that even if the water quality is problematic, the operating cycle can be extended. On average, the operating time can be extended to 5 - 7 times. (154.1 hr / 21.1 hr, 186.2 hr / 26.9 hr, 133.9 hr / 27.5 hr)
In this thesis, the UF membrane which PVDF material obtained after SEM / EDX analysis, when the main component of the scale is iron metal compound (10~15%), using sodium hypochlorite + oxalic acid to the single-membrane cleaning procedure can solve the fouling condition, and the membrane impedance difference can be up to 67.1%. In the real field test section, the membrane pressure after cleaning with sodium hypochlorite + oxalic acid can be reduced from -49.6 kPa, -47.9 kPa, -47.5 kPa to -11.6 kPa, -7.1 kPa, -11.9. kPa, the pressure difference can reach about 75~85%.
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