Calcium alginate (CaAlg) hydrogel filtration membrane was prepared using polyethylene glycol (PEG) as the pore-forming agent. Ultrasonic time-domain reflectometry technology was employed to analyze the membrane-forming process. The CaAlg filtration membrane was characterized by SEM, FTIR, TG and DTG. The mechanical behavior of the membrane was also evaluated. Concentrations of sodium alginate (NaAlg) and PEG on the pure water flux (OWE) and filtration properties of lysozyme (Lyz) solutions were investigated. Results showed that the PWF increased with an increase in the pressure initially, and then reached a stable value. The CaAlg filtration membrane prepared with lower NaAlg concentration and higher PEG concentration had higher flux. CaAlg filtration membranes exhibited good anti-fouling properties. The rejection of PEG reached above 90% when the molecular weight (M-w) of PEG in feed solution was larger than the pore-forming agent PEG for preparing the membranes. The CaAlg filtration membrane prepared using PEG400 as the pore-forming agent could reject almost 100% Brilliant Blue G250 (M-w = 854.02 Da), and 99.5% Congo Red (M-w = 696.68 Da). (C) 2015 Elsevier B.V. All rights reserved