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Pre-treatment optimisation studies for secondary effluent reclamation with reverse osmosis
J A López-Ramírez1, S Sahuquillo, D Sales
1Faculty of Marine and Environmental Sciences, Department of Chemical Engineering, Food Technology and Environment Technologies, University of Cádiz, Polígono Río San Pedro, s/n. 11510, Puerto Real, Cádiz, Spain. juanantonio.lopez@uca.es
Water Research
|January 30, 2003
Summary
This study optimized physical-chemical pre-treatment for reverse osmosis, achieving high-quality reclaimed water suitable for groundwater injection. Effective pre-treatment prevents membrane fouling and ensures water safety.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Membrane Science
Background:
- Secondary effluents require advanced treatment for reuse.
- Reverse osmosis (RO) membranes are susceptible to fouling and biofouling.
- Effective pre-treatment is crucial for RO performance and longevity.
Purpose of the Study:
- To optimize physical-chemical pre-treatment processes for secondary effluent reclamation.
- To evaluate the efficacy of various pre-treatment chemicals and conditions.
- To ensure the suitability of treated water for groundwater injection.
Main Methods:
- Utilized a pilot plant with tertiary treatment units for reverse osmosis.
- Optimized pre-treatment by adjusting pH with lime (10.3-12.1).
- Applied ferric chloride (15-25 mg/L) for coagulation and sodium hypochlorite (8 mg/L) for disinfection.
Main Results:
- Achieved high water quality with optimal conditions: pH 10.5, 25 mg/L FeCl3, 0.5 mg/L anionic flocculant, 8 mg/L sodium hypochlorite.
- Resulting water had an average conductivity of 66 µS/cm and low COD of 4 mg O2/L.
- Treated water met standards for groundwater injection.
Conclusions:
- Optimized physical-chemical pre-treatment effectively reclaims secondary effluent for groundwater recharge.
- The process successfully prevented membrane fouling and ensured microbiological safety.
- Reclaimed water quality is suitable for mitigating seawater intrusion in aquifers.