Parameter Optimization And Scale-Up Experiment Of Algae Removal And Bacteria Inactivationin By Multi-pore Ceramic Filtration And UV Radiation

As unreasonable usage of water, different types and different levels of pollution occur in waters. Among these pollution, algae and bacteria have drawn increasingly attention for its universal existance and explosive and unexpected hazards.By investigation of the existing technologies, and by comparing the advantages and disadvantages of them, the combination treatment of multi-porous ceramic filtration and ultraviolet radiation (MPCF&UV) is poposed for algae and bacteria in water. On the basis of preliminary experiments, the mechanism of MPCF&UV system on algae and bateria is studied, which provides a theoretical basis for further research. By experimental study on the effects of structure parameters of filter, operating conditions are optimized, and key factors of the design and operation are obtained. Meanwhile, damage of treated algae and bacteria are studied, as well as the sustainability and regeneration of the filter. In the sale-up experiments, typical alga removal effects and bateria inactivation effects are compared under different operation conditions, in order to verify the stabilization of MPCF&UV treatment. Additionally, economic feasibility of the system is also evaluated.Firstly, depending on literature investigation and preliminary experimental study, alga removal efficiencies were compared on MPCF, UV, andMPCF&UV treatment respectively. The result showed that wall-flow structure porous ceramic filter removes algae mainly relying on the effects of interception, deposition, inertial sedimentation, asorption and bridging, and the key effects may change with environment. UV lights mainly destroy DNA or RNA of the bacteria via UV radiation to inactivate bacteria.MPCF experimental equipment was set up to remove alga, and total suspended solids (TSS) removal efficiencies and typical alga removal efficiencis were chosen as indicators. Orthogonal experiments were designed to optimize the structural parameters of the MPCF, including filtration channel length, number of channels and size of wall pore. Furthermore, optimal flow rate was obtained. The results showed that considering the limitation of processing, the highest removing effects can be achieved by the filter with the following parameters:the size of wall pore is200meshes, the channel length is152.4mm, and the channel number is1824, and the optimal flow rate is0.6m3/h for a1L filter.Meanwhile, a series of experiments were carried out at the optimal flow rate, and the relationship between accumulated treatment volum (V) and head loss (H) was studied. Backwashing conditions include time span and flow rate were detected by evaluating recovery rates on flux and removal efficiencies.In addition, the UV and MPCF&UV experimental equipements were set up. By orthogonal analysis, the effects of UV dose, the density and size of indicating algae species on the efficiency of bacteria inactivation were studied experimentally. The inactivation results of UV and MPCF&UV were compared, and the morphology of treated bacteria was analyzed by scanning electron microscope (SEM). It concluded that MPCF&UV is obviously superior to UV on bacteria treatment, and first stage treatment of MPCF can effectively raise transmission rate of UV lights and then improve the inactivation effects.The previous study of MPCF&UV system at low flow rates (less than10m3/h) has verified the efficiency and stability in the algae and bacteria treatment. For the practical application, a pilot device at the flow rates of50-100m3/h was designed and established on the basis of the previous study. Water with Dunaliella salina and native seawater have been used respectively to carry treatment tests. The results show that the scale-up MPCF&UV system maintains a high removal efficiency and inactivation efficiency on Dunaliella salina, plankton, and marine bacteria, with no negative amplification effect, and the persistence of the system is verified.Finally, the economic feasibility including installment costs and operation costs of MPCF&UV system was evaluated. The installment costs mainly include costs of main component, the accessories, material, and equipment processing. The operation cost mainly includes power consumption fee, equipment depreciation cost, and labor cost. It indicates that the ratio of installment capital to flow rate of the scale-up system is lower than the small-scale equipment. The combination method has better economy than any other similar method.In summary, MPCF&UV system has high efficiency, stability and economy on algae and bacteria in water. There is no negative amplification effect for scale-up experiment, and it has broad prospects on application.