A hybrid super hydrophilic ceramic membrane and carbon nanotube adsorption process for clean water production and heavy metal removal and recovery in remote locations

Abstract

A novel hybrid membrane-adsorption process has been developed for the production of clean water supplies. A 0.2μm ceramic membrane has been functionalised to produce a super-hydrophilic surface on the microfiltration membrane capable of maintaining flux with little or no fouling under normal operating conditions. The adsorbent used is a supported epoxidised carbon nanotube material capable of removing heavy metals from solution. Both the membrane and the adsorbent can be easily cleaned when necessary using only a solution of readily available vinegar. The intended aim for this new water production system is for the production of clean water in remote locations, in disaster relief zones and for humanitarian purposes. Laboratory studies have shown that the membrane is capable of maintaining flux over a significant period of time and even when tested with an extreme foulant (used motor oil) performed admirably. The rejection properties of the membrane are as expected for small pore microfiltration, i.e. microbial contamination is easily removed. The adsorbent was shown to remove heavy metals (Cd, Hg, Ni, Co and Pb) to a very high degree (>99.3% in all cases) and was easily regenerated to almost complete adsorptive capacity. The hybrid-process was briefly deployed to the Rio Las Vacas (Guatemala) as part of a basic feasibility study and the unit performed as expected. No microbial contamination was detected in the permeate and the flux was maintained consistently at one third of the clean water flux. This demonstrates the system is capable of microbial removal and has good antifouling properties.