Research On Treatment Of Algae-laden Water And Membrane Flux Model With Combined Membrane Technology

For the contradiction between people’s growing demands for drinking water quality and the limitations of conventional water treatment processes, the more cost-effective technology came into being. The membrane separation technology, such as ultrafiltration and reverse osmosis, is increasingly being applied to water treatment. The paper discusses the effect of removal of the double membrane process for some organic pollutants in water. In the premise of ensuring safe drinking water, in-depth study of membrane fouling process was carried to provide theoretical guidance for selecting membrane process parameters and cleaning time. In order to ensure water quality and reduce membrane fouling, and then prolong membrane life.At present, the problem of global water eutrophication is getting worse and water blooms in lakes and reservoirs occur frequently. Eutrophication can cause algal aquatic phytoplankton grow explosively, in which blue-green algae is the main species in freshwater. Blue-green algae blooms may produce algal toxins which will pose a threat to aquatic life and human health. For this situation, and low efficiency of conventional treatment for algae, algal toxins and some dissolved organic matter, the experiment of ultrafiltration and reverse osmosis membrane dealing with surface water containing algae was carried out to improve this situation and provide some data for membrane treatment process. The experimental results show that ultrafiltration has a good retention for chlorophyll a and turbidity, and the removal rates are91.8%and98.2%, respectively. The removal rate of COD is higher than UV254, respectively62.04%and45.34%, which may be due do the pore size of ultrafiltration membrane is relatively large, so the removal of dissolved organic matter is limited. Reverse osmosis membrane retention effect for dissolved organic matter and algal toxins is obviously and the removal rates are98.14%and96.01%, respectively. Thus, reverse osmosis water can meet drinking water standards. Sand filter water directly flow into the ultrafiltration device and the changes of ultrafiltration membrane flux with time is relatively large. The change of flux can be divided into three stages.In the case of water quality assurance, in-depth study of membrane fouling was carried out. Based on the original membrane flux model, the new ultrafiltration, reverse osmosis membrane flux model which can be used to simulate the changes of membrane flux with time was derived. Meanwhile, scanning electron microscopy, infrared spectroscopy and mercury intrusion method were used to analysis the surface morphology of ultrafiltration membrane, the main material causing membrane fouling and the changes of pore size or porosity. Scanning electron microscopy showed the process of membrane fouling. IR spectra showed that the main fouling material are polysaccharides, nucleic acids and proteins and other organic matter. The changes of pore size and porosity indicated that a three-stage classification membrane flux is reasonable. Finally, the derived membrane flux model was verified by experimental data, and the correlation coefficient of experimental values and simulation values is greater than0.95. The validity of the model for predicting the process of membrane fouling was proved, and some theoretical support for ultrafiltration, reverse osmosis membrane fouling was provided.