Study on Sensors for Environment Monitoring

Sammanfattning: Nowadays, the role water quality played has become more and more important, especially in the industrial field, which can directly impact the cost and quality of the products. Similarly, the quality of wastewater directly impacts the efficiency of the reuse and discharge of wastewater. To monitor the parameters during the process of waste water treatment, an exited Wireless Sensor Network service is proposed. The object of this article is to investigate the methods of wireless sensor on the main nods of the WSN system. The set of water quality standards is depended on the different requirements in different specials. This article was concerned about PH, dissolved oxygen, turbidity and chlorine which are the key parameters of water quality for industrial. Generally, there are two ways to measure the indicators, electrochemical and optical. In this article, the investigation is based on these two ways. The most suitable way to sense the PH value is using PH sensitive electrode. Two ways to monitor the dissolved oxygen, optical methods and electrode method, are introduced and compared. This thesis also introduced how to measure the turbidity with optical components. Two most common principals for chlorine are introduced and compared; one is called DPD colorimetric detection which is based on N, N-Diethyl-p-Phenylenediamine (DPD) reaction with active halogens, the other is called Amperometry which is en electrochemical technique that measures the change in current resulting from chemical reactions taking place as a function of the analytic concentration. Based on the principals introduced above, two experiments are proposed. One is for the PH measurement. The test circumstance consists of a relatively inexpensive PH electrode, a voltmeter and a reference PH meter. The other one is for the turbidity measurement which consists of two LEDs and a light-to-voltage sensor.