Pre-coagulation and ultrafiltration of effluent impaired surface water for phosphorus removal and fouling control

• Published in: Water science & technology. Water supply 2011-01, Vol.11 (2), p.211-218
• Main Authors: PAAR, Hendrik, BENECKE, Jan, ERNST, Mathias, JEKEL, Martin
• Format: Article
• Language: English
• Subjects: Applied sciences; Biopolymers; Buildings. Public works; Capacity; Coagulants; Coagulation; Detection; Dosage; Exact sciences and technology; Ferric chloride; Filter cake; Filtration; Fouling; Fouling control; Freshwater; Influents; Liquid chromatography; Macromolecules; Membrane filtration; Membranes; Organic carbon; Organic chemistry; Orthophosphate; Pathogens; Phosphates; Phosphorus; Phosphorus removal; Quality standards; Removal; Stability; Studies; Surface water; Ultrafiltration; Wastewater; Wastewater treatment; Water supplies; Water supply. Pipings. Water treatment
• ISSN: 1606-9749; 1607-0798
• DOI: 10.2166/ws.2011.037

The process combination of in-line coagulation and subsequent membrane filtration is a suitable advanced treatment stage to achieve higher quality standards regarding pathogens and phosphorus in biologically treated wastewater prior to its discharge into sensitive water bodies. In this study a membrane pilot installation (capacity of 6 m3/h) was operated in dead-end configuration to investigate phosphorus removal and fouling behaviour depending on FeCl3 dosage. In parallel, effects of in-line coagulation on the filtration behaviour were investigated in lab-scale filtration experiments. The coagulation leads to the predominant reduction of dissolved organic macromolecular substances which are detected as biopolymer fraction by liquid chromatography-organic carbon detection. Besides the removal of dissolved organic molecules, the resulting filter cake plays a major role for the performance of ultrafiltration. In lab-scale filtration experiments the in-line coagulation results in positive effects on the filtration stability. In contrast, high coagulant doses lead to the loss of filtration performance during the pilot operation. The installed in-line coagulation, however, successfully reduced the orthophosphate concentration in permeate to values below 30 μgP/L when operated at a fixed molar ratio of FeCl3 concentration to influent PO4-P concentration of 6 (ßPO4-P-value).