On-line Heavy Metal Detecter Based On Embeded Platform

Events caused by the heavy metal pollution occurred frequently in recent years, which seriously harm people’s health. In order to protect the human body and natural environment from the danger of heavy metal, the real-time monitoring technology for the heavy metal ions in water is becoming very important. However, the existing heavy metal online detection systems are difficult to promote, because their cubage is large and cost is much. This paper will design a heavy metal detector, which has characters of small volume, low cost and supports for online detection.The system chose anodic stripping voltammetry as heavy metal detection method through a brief comparison and analysis of a variety of methods, which can detect multiple elements at the same time, and suitable for online detection. The heavy metal detector was composed of data collection system, embedded control system and PC client. The hardware part of collection system mainly includes constant voltage circuit, weak signal collection circuit and hardware inspecting circuit. The main function is receive and parse the instructions, which was sent by control system,then control the DAC output waveform, at the same time, the data packets are formed by the ADC data collection, and the data packets will be sent to the control system through the USB bus. Control system based on embedded ARM platform can control the data collection system work orderly through sending data. Then it will process the packets received from collection system by wavelet transform denoising technology, and draw VA characteristic curve. We can qualitatively and quantitatively detect the type and concentration of heavy metals. System will create a simple and convenient interactive touch-screen interface to control operate and observe the results. PC client can receive and save the detection reports through the network interface.Finally, the function of the heavy metal detector is examined. We choose Cu, Ag, Zn three heavy metals ions as test samples to be detected, the result is that they separately have a good linear relationship in the range of 10-200 ppb, 10-500 ppb, 20-500 ppb, and detection limits are 0.4ppb, 0.81 ppb, 2.15 ppb. The heavy metal detector can simultaneously detect multiple ion characteristics in the field, which has high stability, low detection limit, small size and friendly user interface.