Integrated in-line coagulation-aerated ultrafiltration for drinking-water production: A case study from laboratory to pilot plant

Abstract

A pilot-scale study was made for drinking-water production from low-quality influents with in-line coagulation as pre-treatment of aerated ultrafiltration. Optimum flocculation parameters were previously determined in the laboratory, searching for large and strong flocs that could resist aeration without increasing the membrane fouling. Nevertheless, the comparison of the jar tests and the pilot-scale results showed that the former could help pre-dimensioning the flocculation facilities but could not precisely reproduce the behavior of the flocs in the membrane tank. The optimum coagulant dosage enabled the highest dissolved organic carbon (DOC) removal without affecting membrane fouling. Additionally, as opposed to the jar-test results, long retention times led to the lowest fouling rates while the velocity gradient affected neither the effluent quality nor the membrane fouling. These findings suggested that the influence of the flocculation parameters was masked by aeration inside the membrane tank but, even so, 43% and 82% DOC and UVA₂₅₄ removals, respectively, were reached. Furthermore, the growth of the total membrane resistance with time was logarithmic instead of linear, confirming the suitability of the pre-treatment for low-quality influents.

Keywords:

• Aeration
• in-line coagulation
• low-quality influents
• membrane fouling
• ultrafiltration

Acknowledgments

The present study was conducted at the Institute of Water Research (University of Granada) and Parque de las Ciencias, Granada (Spain) with the collaboration of CADAGUA S.A.

Funding

This study was included within the CTM2010-18899-TECNO project, supported by the Spanish Ministry of Science and Innovation.