Membrane Coagulation Reactor Process For The Micro-polluted Surface Water Treatment And Cost-benefit Analysis

With the conflict of water source pollution and stringent Sanitary Standards for Drinking Water, it is necessary to develop new technology and devices for drinking water treatment. Membrane separarion, an important technique to get safe drinking water, has been increasingly concerned in the field of water and wastewater treatment while the price of the material is reduced and the performance of the membrane is improved. Under such circumstances, microfiltration is widely used in drinking water production because of the steady quality of finished water and easy automation with low operating pressure. To put the membrane coagulation reactor (MCR) process into practical use, it is important to investigate the operation dependability, the design method of the full-scale MCR, and the economic feasibility.In this experiment, MCR used for the treatment of water from Lake Qingnian of Tianjing University were investigated. The capacity of experimental device was 0.3~0.5 m3/h. The result indicated that there were good removals of turbidity, bacteria and organic pollutants when proper dosage of ferric chloride and PAC were added. Turbidity and total amount of bacteria in finished water were respectively less than 0.3 NTU and 100 CFU/mL. When raw water belonged in class â…¤ defined by Environmental Quality Standards for Surface Water (GB3838-2002), the finished water quality met the requiement of Sanitary Standards for Drinking Water (2001) and when the quality of the raw water was poorer than class â…¤, the finished water quality was very close to the Standard. During the experiment, membrane specific flux decreased gradually. After purifying 150 m3 water, the membrane was cleaned with physical methods and the specific flux recovered to 93.61% of the new membrane. Experimental results showed that this device is of great potential in field army and emergence water supply.According to the experimental results, the design method and general procedures for MCR process were developed. It was suggested that the hydraulic residence time (HRT) be the main design parameter. A project design of micro-polluted water treatment plant for a county was done in this thesis.Based on cost-benefit analysis, the MCR is a process with higher energy consumption and treatment cost compared with aerated biological filter - conventional water treatment process or conventional water treatment with O3 - powdered activated carbon (PAC) process. If the cost of membrane modules could be reduced 20%, the economic parameters of MCR would be similar to those of the conventional water treatment with O3-PAC process.