Development of new membranes for desalination pre-treatment

Desalination pre-treatment;Water purification;membrane development

Qadir, Ahmad ; Shannon ; Mark A.

关键词: Desalination pre-treatment;    Water purification;    membrane development;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/26369/Qadir_Ahmad.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The use of membranes in water filtration is on the rise as they are reliable and filter wide variety of pollutants and fouling agents. On the other hand, fouling of the membrane and initial cost of the setup and the membrane itself are the areas which need major improvement. In this thesis, testing and development of new MF and UF membranes are studied which are roughly 10 times cheaper than commercial membranes. Pre-treatment for desalination was chosen as an application for these new membranes, based on the fact that desalination is a growing technology, especially in areas where there is lack of fresh water and also because seawater contain wide variety of fouling agents.To develop and test the new membranes, test bench was setup to evaluate and compare the performance of new and commercial membranes. Backwash system was introduced into the system to test the membranes for longer period of time.Membrane characterization is an essential part of development of the membrane. Pure water permeability and pore size distribution are the basic characteristics of any porous material. Mercury porosimetry, bubble point tests and molecular weight cut off experiments were done to study the pore structure of these new membranes and based on the results of pure water permeability and pore structure, membrane formulation was modified to achieve higher flux and better pore size distribution. Finally, higher fluxes than commercial MF membrane were achieved while also having slightly better average pore size. The new membranes were also challenged with synthetic seawater containing algae, organic acids, silt and salt. They performed better than commercial membranes in terms of fouling when challenged with silt and organic acids but they struggled against algae. To check the durability of these new membranes, quality of water was consistently checked with turbidimeter and particle size analyzer and quality of water was under required levels even after consistently running the experiments for 4 days. Irreversible fouling by algae was found to be slightly reduced when these new membranes were coated with FDTS (fluorodecyltrichlorosilane). These membranes are still in the development stages and need to be tested against other fouling agents to find the suitable market for them and different surface treatments could make them application specific.