The development of automatic monitoring technology

Development status of water quality automatic monitoring technology and automatic monitoring instruments

1 Preface

water quality automatic monitoring system is a comprehensive automatic monitoring data, which is composed of automatic analysis instruments as the core, using modern sensor technology, automatic measurement technology, automatic control technology, computer application technology and related special analysis software and communication to meet the needs of the domestic rapid development of the automotive industry. It can count and process monitoring data, and can print out daily, weekly, monthly, quarterly The annual average data, daily, weekly, monthly, quarterly, annual maximum, minimum and other monitoring, statistical reports and charts (bar chart, curve chart, multi track chart, comparison chart, etc.) can be input into the central database or. Collect and store designated monitoring data, various operation data and environmental data for retrieval. The system has the functions of monitoring items exceeding the standard and sub station status signal display and alarm; Automatic operation, power failure protection and automatic recovery of incoming calls; The maintenance and inspection status test is convenient for routine maintenance and emergency troubleshooting

the implementation of automatic water quality monitoring can realize real-time continuous monitoring and remote monitoring of water quality, achieve and master the water quality status of key sections of major river basins, early warning and prediction of major or river basin water pollution accidents, solve disputes over water pollution accidents across administrative regions, supervise the implementation of total amount control system, discharge standards and other purposes

2 automatic water quality monitoring technology

2.1 composition of automatic water quality monitoring system

in the automatic water quality monitoring system network, the central station realizes the functions of real-time monitoring, remote control and data transmission of each sub station through satellite and dial-up communication, and the hosting station can also realize the functions of real-time monitoring, remote control and data transmission of the entrusted pipe station through dial-up, Other authorized relevant departments can produce real-time monitoring of relevant sub stations through dial-up mode, so that domestic excellent experimental instruments and equipment can be widely used for video and data transmission

each sub station is an independent and complete automatic water quality monitoring system, which is generally composed of six main subsystems, including sampling system, pretreatment system, monitoring instrument system, PLC control system, data acquisition, processing and transmission subsystem, remote data management center, monitoring station building or monitoring cabin. At present, the subsystem of water quality automatic monitoring system and remote data management center, monitoring station building or monitoring cabin. At present, there are three kinds of sub stations in the automatic water quality monitoring system:

(1) sub stations composed of one or more small multi parameter water quality automatic analyzers (such as the conventional five parameter analyzers of ys1 company and Hydrolab company) (multiple combinations can be used to measure water quality in different depths). Its characteristic is that the instrument can be directly placed in water for measurement, and the system composition is flexible and convenient

(2) fixed substation: it is a more traditional system composition mode. It is characterized by a wide range of monitoring items

(3) mobile sub station: one is a fixed sub station. All instruments and equipment are installed on a trailer (monitoring cabin), which can be moved according to needs. It can also be considered as a semi fixed rock tensile strength sub station, which can be divided into two types: direct method and direct method. It is characterized by high composition cost

each unit is interconnected through water sample transmission pipeline system, signal transmission system, compressed air transmission pipeline system and pure water transmission pipeline system

a highly reliable automatic water quality monitoring system must have four elements at the same time, namely (1) high-quality system equipment; (2) Complete system design; (3) Strict construction management; (4) Responsible for operation management

2.2 technical key of automatic water quality monitoring

2.2.1 water collection unit

includes water pump, pipeline, power supply and installation structure. In the design, corresponding solutions must be proposed for various climates, landforms, water level changes and sediment in the water, which can automatically and continuously work synchronously with the whole system and provide the system with feasible and effective water samples

2.2.2 water distribution unit

includes water sample pretreatment device, automatic cleaning device and auxiliary parts. The water distribution unit directly supplies water to the automatic monitoring instrument, with sediment removal and filtration, manual and automatic pipeline backwashing and algae removal devices; Its water quality, water pressure and quantity shall meet the needs of automatic monitoring instruments

2.2.3 the analysis unit

is composed of a series of automatic water quality analysis and measurement instruments in case of brittle fracture of most products, including: water temperature, pH, dissolved oxygen (do), conductivity, turbidity, ammonia nitrogen, chemical oxygen demand, permanganate index, total organic carbon (TOC), total nitrogen, total phosphorus, nitrate, phosphate, cyanide, fluoride, chloride, phenols, oils, metal ions, water level gauge It is composed of flow/flow/direction meter and automatic sampler. The development status of main automatic analysis instruments will be detailed in Section 3

2.2.4 control unit

includes: (1) system control cabinet and system control software; (2) Data acquisition, processing and storage and its application software; (3) Wired communication and satellite communication equipment

2.2.5 substation building and supporting facilities

include: (1) main body of station building; (2) Supporting facilities

3 development of automatic analysis instruments

3.1 overview

automatic water quality monitoring instruments are still developing, and some professional manufacturers produce them in Europe, the United States, Japan, Australia and other countries. At present, the more mature conventional projects include: water temperature, pH, dissolved oxygen (do), conductivity, turbidity, oxidation-reduction potential (ORP), flow rate and water level. Common monitoring items include COD, permanganate index, TOC, ammonia nitrogen, total nitrogen and total phosphorus. Others include: fluoride, chloride, nitrate, nitrite, cyanide, sulfate, phosphate, active chlorine, Tod, BOD, UV, oil, phenol, chlorophyll, metal ions (such as hexavalent chromium), etc

current automatic analyzers generally have the following functions: automatic range conversion, remote control, standard output interface and digital display, automatic cleaning (with data locking function during cleaning), status self inspection and alarm functions (such as liquid leakage, pipeline blockage, out of range, instrument internal temperature is too high, reagent ruler, high/low concentration, power failure, etc.), dry operation and power failure protection, automatic recovery of incoming calls, COD, ammonia nitrogen, TOC Total phosphorus, total nitrogen and other instruments have the function of automatic calibration and correction

3.2 conventional five parameter analyzer

conventional five parameter analyzer often adopts the structure of flow-through multi-sensor measuring cell, without zero drift, without baseline correction, and has integrated biological cleaning