A Study And Design About The Rapid Bioluminescent Bacterium Monitoring Equipment Of Water Toxicity

With the development of the process of industrialization, the number and variety of toxic and harmful substances increases rapidly, which has negatively affected urban sewage treatment plants. Therefore, before discharged into the municipal sewage treatment plant, the sewage must be tested. Then appropriate measures must be taken according to test results as an early warning to ensure normal operation in plants. It is supposed to design a rapid bioluminescent bacterium monitoring equipment of water toxicity.First of all, the isolated bioluminescent bacterium is proved to be Vibrio fischeri. This research reveals that it enters a stable growth period at the 24^th hour and achieves maximum luminous intensity at the 22^nd hour. The autoinducer of bioluminescent bacteria is studied based on the principle of quorum sensing system. With the introduction of autoinducers, the light-emitting time of bioluminescent bacteria is 6h earlier, and the luminescence intensity and stability of the lyophilized bioluminescent bacteria is enhanced. The recovery time of the lyophilized bioluminescent bacteria is reduced to 5min, 10min quiker than traditional methods.Secondly, through the combination of biosensor technique and toxicity monitoring technique with bioluminescent bacteria as test subjects, an easy, quick, and sensitive bioluminescent bacterium monitoring equipment is designed to detect the acute toxicity of pollutants, which determines the comprehensive toxicity level of water pollutants. Items used in the design are as following: R105 side window photomultiplier tube as detector which turns the optical signals into the electrical signals, a photoelectric detection circuit which can change the faint current to the voltage of 0～5 V, and achieve low-pass filter of 30KHz and a microcontroller LPC2103 as a processor for A/D conversion and data analysis.Finally, in order to test the performance of the equipment based on quorum sensing system, unary and binary heavy metal toxicity experiments have been carried out. The focus goes to applicable conditions of the equipment, unary heavy metal toxicity, binary joint toxicity of heavy metals, the main factor effect analysis, and the interaction between two factors. Compared with the existing toxicity testing methods, the water toxicity monitoring equipment with the help of bioluminescent bacterium based on quorum sensing system presents a better performance, and lays a solid foundation for the design of the online and early warning system to detect the toxicity of pollutants.