Proof of Concept for Light Conducting Membrane Substrate for UV-Activated Photocatalysis as an Alternative to Chemical Cleaning

Abstract

Adopting an effective strategy to control fouling is a necessary requirement for all membrane processes used in the water/wastewater treatment industry to operate sustainably. The use of ultraviolet (UV) activated photocatalysis has been shown to be effective in mitigating ceramic membrane fouling by natural organic matter. The widely used configuration in which light is directed through the polluted water to the membrane’s active layer suffers from inefficiencies brought about by light absorption by the pollutants and light shielding by the cake layer. To address these limitations, directing light through the substrate, instead of through polluted water, was studied. A UV conducting membrane was prepared by dip coating TiO2 onto a sintered glass substrate. The substrate could successfully conduct UV from a lamp source, unlike a typical alumina substrate. The prepared membrane was applied in the filtration of a humic acid solution as a model compound to study natural organic matter membrane fouling. Directing UV through the substrate showed only a 1 percentage point decline in the effectiveness of the cleaning method over two cleaning events from 72% to 71%, while directing UV over the photocatalytic layer had a 9 percentage point decline from 84% to 75%. Adapting the UV-through-substrate configuration could be more useful in maintaining membrane functionality during humic acid filtration than the current method being used.

Sunlight-Transmitting Photocatalytic Membrane for Reduced Maintenance Water Treatment

“…The sintered glass substrates were then mechanically dipped into the suspension, followed by air drying for 12 h and heating in a muffle furnace to 450 °C at a rate of 1 °C/min. Cooling was at the same slow rate to prevent cracking, followed by washing in DI water and drying at 80 °C for 2 h. Successful uniform coating of TiO 2 on the substrate was confirmed by a combination of gravimetric and visual inspections, as well as scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), as reported in previous work. , …”

“…Introducing natural sunlight faces similar practicality issues. In an attempt to resolve the membrane and module limitations, we showed how light transmitting sintered glass membrane substrates can be adopted to solve these challenges. , Light conducting substrates are new to membrane science and could give the possibility of solving the challenge of introducing a light source from outside the module (e.g., sunlight or artificial UV source) to the catalyst coating, whereby light directed from the outside (toward the end and/or side) of the membrane element enclosed in a transparent (glass or polymer) housing allows light to be transmitted through the substrate along its entire length while simultaneously distributing light (e.g., by light scattering) to the entire membrane’s photocatalyst coating. This is especially viable in the industry standard ceramic membrane monolith format, where its end and sides can be simply exposed to the sun within a transparent housing to “illuminate” the substrate and distribute/scatter light to the entire photocatalytic membrane surface.…”

Photocatalytic Nanofiber Membranes for the Degradation of Micropollutants and Their Antimicrobial Activity: Recent Advances and Future Prospects

“…There is ongoing research on hybrid membrane materials which may lead to new and more efficient ways of water treatment which align with drinking water and environmental safety regulations. Figure 15 illustrates the reduction in membrane fouling achieved by coating membranes with photocatalytic materials such as TiO 2 [ 161 ].…”

“… Membrane fouling reduction induced by the addition of TiO 2 coating through photodegradation. Reprinted from [ 161 ]. …”

Development and applications of novel nanostructured materials in water treatment : adsorption, filtration, and reaction

“…[163], as mentioned in Table 5.1. Thus, improved treatment technologies, readily available and simple to operate, could support actions to increase widespread access to clean water [164].…”