Oestrogen removal from biological pretreated wastewater within decentralized sanitation and re-use concepts

Two parallel researches were performed; one focused on the fate of oestrogens in the biological treatment systems within decentralised sanitation and re-use concepts (DESAR), the second related to the development of a suitable specific removal method. A new affinity membrane was developed using antibodies as specific binding sites for hormone removal. It was found that, especially in anaerobic treatment, the core technology in DESAR, the removal is insufficient and therefore an additional separation method is required. The affinity membrane with antibodies was found to be a suitable additional method, though in the current system it only removes one selected compound. Future research will focus on making this method more feasible in practis

Polymer-in-a-silica-crust membranes: macroporous materials with tunable surface functionality

We report on alkaline hydrolysis of tetraethoxysilane (Stöber synthesis) inside a macroporous polymer matrix resulting in a homogeneous coverage of silica onto the polymer surface. The encapsulation of the polymer struts by a continuous silica crust allows further functionalization with hydrophilic and hydrophobic silylating agents. The porous silica polymeric hybrid material combines the morphological control and mechanical flexibility of the polymeric matrix with the convenient surface modifications developed for glass and amorphous silica. This concept is applied to macroporous membranes where alteration in surface functionality allows tuning of hydrophobicity (contact angle and liquid entry pressure), streaming potential, and adsorption capacity of double-stranded DNA

Affinity membranes for hormone removal from aqueous solutions

A novel affinity membrane was prepared by covalent binding of antibodies (against 17--estradiol) to a micro-porous poly(ethylene vinyl alcohol) (EVAL) membrane, taking benefit from the high surface area of EVAL membranes and the large number of reactive groups available for further surface modification. The covalent coupling of the antibody occurred via its non-specific chain to maximize the number of available binding sites for hormones. To achieve this site-oriented coupling first poly(ethylene glycol) bis-hydrazide (PEG-Hz) was reacted with glutaraldehyde-modified EVAL membrane, followed by coupling of oxidized antibody to the PEG-Hz spacer arm. Confocal microscopy demonstrated that most of the antibodies were grafted on the outer surface, rather than inside the membrane. In dynamic filtration, 17-- estradiol was retained for 99%. The specificity of the membrane was demonstrated by its capability to distinguish 17--estradiol from the nearly identical compound estrone

Hybrid silica – polymer macroporous membranes with tunable surface functionality

We report a generic synthetic route to prepare polymer-silica hybrid membrane with tunable porosity and surface properties. First, a macroporous polymeric membrane is prepared using immersion precipitation technique. Subsequent encapsulation of the polymer matrix with a continuous silica layer, substitutes the surface properties of the polymer by the silica layer. This enables the use of the rich spectrum of silica functionalisation techniques. Hydrophilization and hydrophobization to control wetting properties of the macroporous hybrid membrane are evaluated