In-line coagulation with low-pressure membrane filtration
Kevin Young-june Choi1, Brian A Dempsey
1Department of Civil and Environmental Engineering, The Pennsylvania State University, 212 Sackett Building, University Park, PA 16802, USA. yjc103@psu.edu
Water Research
|October 20, 2004
Summary
In-line coagulation effectively removes natural organic matter and turbidity during ultrafiltration. This method improves membrane performance by reducing fouling and enhancing filter cake removal.
Area of Science:
- Water treatment technologies
- Membrane filtration
- Coagulation chemistry
Background:
- Conventional water treatment involves multiple steps for particle and natural organic matter (NOM) removal.
- Ultrafiltration (UF) is a membrane process susceptible to fouling by NOM and turbidity.
- Optimizing pre-treatment is crucial for efficient UF performance.
Purpose of the Study:
- To evaluate the impact of in-line coagulation on NOM and turbidity removal during ultrafiltration (UF).
- To assess the effect of in-line coagulation on membrane fouling and hydraulic performance.
- To compare different coagulation strategies (charge neutralization, sweep floc, under-dose) in conjunction with UF.
Main Methods:
- Coagulants were added directly before UF without intermediate conventional treatment steps.
- Synthetic and natural raw waters were used to test the in-line coagulation-UF process.
- Evaluated NOM and turbidity removal, filtration resistance, and filter cake characteristics.
Main Results:
- In-line coagulation, including charge neutralization and under-dose conditions, effectively removed NOM and turbidity via UF.
- Most coagulation conditions led to reduced filtration resistance and improved filter cake removal.
- Flocs formed under charge neutralization and acidic under-dose conditions exhibited lower hydraulic resistance and compressibility compared to sweep floc.
Conclusions:
- In-line coagulation is a viable strategy for enhancing NOM and turbidity removal in UF systems.
- This approach can improve UF membrane performance by mitigating fouling and improving cake management.
- Specific coagulation conditions, such as charge neutralization, offer advantages in reducing hydraulic resistance and compressibility.
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