Today, with the rapid economic development, the negative impact of the exchange of environment for economic benefits has gradually become more prominent. The pollution of heavy metals to the environment and the impact on the environment and humans are extremely prominent. The hazards of heavy metal pollution to the human body are mainly "three causes", which are carcinogenic, disease-causing, and mutagenic. The way is generally through the biological chain and biological enrichment, and finally enter the human body.
Heavy metal pollution is generally divided into three categories:
1) Soil pollution: obvious regional and easy to control;
2) Water pollution: it has very strong diffusibility and is difficult to control;
3) Atmospheric pollution: It has very strong diffusibility, but the diffusion range is limited and easy to control.
Among them, water pollution is the most serious and difficult to control heavy metal pollution, and also the most harmful to the environment and human body.
Current status of heavy metal water pollution
In recent years, heavy metal pollution accidents have occurred frequently. The only cadmium pollution incidents occurred in 2005 were the severe cadmium excessive incidents in the Shaoguan section of Beijiang, Guangdong, the cadmium pollution accidents in the Zhuzhou section of Hunan, Hunan, in 2006, and the cadmium in Liuyang, Hunan, 2009 Pollution incident.
As for other heavy metal pollution incidents, the “Blood Lead Exceeded Standards†incident alone has involved Shaanxi, Anhui, Henan, Hunan, Fujian, Guangdong, Sichuan, Hunan, Jiangsu, Shandong and other provinces.
According to data from the Ministry of Environmental Protection, the heavy metal pollution incident in 2009 caused 4035 people to exceed blood lead and 182 people to exceed cadmium, triggering 32 mass incidents.
The treatment and monitoring of water quality heavy metals cannot be delayed.
Online monitoring policy for heavy metal water pollution
The main task of environmental monitoring is to obtain environmental monitoring data in a timely, accurate and comprehensive manner, objectively reflect the environmental quality status and change trend, timely track the changes of pollution sources, accurately warn of various potential environmental problems, and respond to unexpected environmental events in a timely manner.
The “Twelfth Five-Year Plan for Comprehensive Prevention and Control of Heavy Metal Pollution†pointed out that the five major industries of mining, smelting, lead storage batteries, leather and its products, chemical raw materials and their products have become the key industries for the prevention and control of heavy metal pollution. Ten billion yuan as a unit to increase investment in the prevention and control of heavy metal pollution. "
The Plan lists 14 key provinces and regions and 138 key prevention and control areas for heavy metal pollution prevention in Inner Mongolia, Jiangsu, Zhejiang, Jiangxi, Henan, Hubei, Hunan, Guangdong, Guangxi, Sichuan, Yunnan, Shaanxi, Gansu, and Qinghai . In the next five years, the state plans to invest 75 billion yuan to carry out comprehensive prevention and control of heavy metal pollution, and key prevention and control areas will receive key support from national project funds.
"Planning" requirements: by 2015, the emission of heavy metal pollutants such as lead, mercury, chromium, cadmium and metal arsenic in key areas will be reduced by 15% compared with 2007; the discharge of key heavy metal pollution in non-key areas shall not exceed Level. For the first time, the goal of total heavy metal control is proposed, which means that the prevention and control of heavy metal pollution will adopt a combination of total control and concentration control. It is reported that there are five main types of heavy metals under national total control, namely mercury, chromium, cadmium, lead and metal-like arsenic.
Technical progress of on-line monitoring of heavy metals in water
Market demand and policy guidance will definitely promote the innovation and progress of the heavy metal online monitoring instrument market, and will gradually become standardized, standardized, and industrialized. The development and progress of the heavy metal online monitor have the following three aspects:
1. Progress of testing technology
The new situation presents new challenges and requirements for the detection of heavy metal pollution in the water environment, which will lead to more simpler, more accurate and more stable detection methods.
Judging from the current detection technology, ICP-MS has many advantages. In the field of environmental monitoring, ISO and other international organizations and developed countries (such as the United States) have successively formulated standards or technical specifications that use ICP-MS technology in the 20th century.
Because the application of the new electrochemical sensor in the anodic stripping voltammetry reduces the detection limit of the instrument and can carry out portable field monitoring, the US EPA lists it as the standard detection method.
Laser-induced breakdown spectroscopy is widely used in recent years due to its high sensitivity and multivariate detection.
Enzyme inhibition, immunoassay, biosensors and other new heavy metal detection methods, as the detection technology matures, will also play an important role in the detection of heavy metals in the water environment.
2. More mature and reliable automatic control technology
Laboratory testing of heavy metals is relatively cumbersome and requires accurate quantification. There are many types of reagents used and most of the reagents contain highly toxic components. In particular, trace analysis of heavy metals in surface water is more difficult, and even experienced laboratory technicians cannot make 100% accurate measurements. To achieve the same or better results as the online heavy metal analyzer, the instrument requires finer, more accurate and more stable.
Ankong Technology successfully applied the Super Series RTU developed by itself to the heavy metal water quality monitoring instrument, which greatly improved the applicability and accuracy of the instrument. Its characteristics are as follows:
Stronger control performance: online analytical instruments need to have unattended, fully automatic analysis, fault self-diagnosis and automatic recovery functions, which requires the instrument to have a smart brain, Super E series RTU is such a smart brain. It uses 32-bit ARM high-performance low-power microprocessor, equipped with 128M memory, executable C language, ladder diagram and other programs, which can completely replace people to monitor on the spot, reduce labor requirements, and avoid human exposure to poisonous Risks caused by pharmacy.
More accurate measurement: The analysis of heavy metals requires very accurate measurement of samples and reagents. We use the method of measuring tube plus photoelectric measurement. The photoelectric sensor simulates the process of judging the liquid level by the human eye, but avoids errors caused by angle, light and personal differences. The signal of the photoelectric sensor is received and recognized by the RTU, which can accurately measure the amount of reagent, and the consistency is better than manual Measurement.
The analysis is more accurate: the heavy metal analyzer uses a colorimetric method to quantitatively analyze the heavy metals in the water body. The monochromatic light is absorbed by the specific substance in the water body through the water body, and the attenuated light is received by the photodiode to generate a micro current. Generally, the range of heavy metal analysis instruments is only a few milligrams, and the rate of change of current is in the microampere level. To identify such a small signal, the requirements for the amplifier circuit are very high. Super E series RTUs are designed for such instruments with high precision and low zero drift. , Intelligent amplifier circuit with low temperature drift and anti-interference. Moreover, the zero point and measuring range of the circuit can be set through the human-machine interface, and the user does not need to perform circuit board-level operations.
Communication is more flexible: RTU is called a remote terminal control system in the industry, and its communication function is unmatched by other PLCs, single-chip microcomputers and other industrial controllers. Heavy metal analyzers are generally installed near more remote water bodies or unattended station buildings. If people want to check the data on the spot in time, they need the equipment to have a communication function. SuperE series RTU is equipped with analog, RS232, RS485, Ethernet, GPRS and other interfaces, and built-in Modbus RTU, Modbus ASCII, TCP \ IP, DNP3.0, environmental protection 212 and other protocols. The user can flexibly choose the communication method according to the actual situation.
Stronger environmental adaptability: Ankong Technology's SuperE series RTU has tens of thousands of applications in extremely harsh environments such as Xinjiang, Inner Mongolia and Kazakhstan, and its environmental adaptability exceeds imported products. Although most of the heavy metal analyzers are installed in the analysis room, the ambient temperature is usually maintained at room temperature, but most water quality monitoring stations have the same characteristic of being moist, especially the pollution source monitoring station is not only wet but also contains a lot of corrosive gases in the water vapor It is generally difficult to find out the faults caused by the corrosion of precision devices in the equipment. Ankong carried out a unique moisture-proof and anti-corrosion treatment on the surface of the Super RTU circuit, and carried out targeted detection before leaving the factory, completely eliminating the damage caused by corrosion to the instrument.
3. The pertinence of the monitoring plan
Because heavy metal pollution is very small, it is easy to be affected by other environmental factors during the detection process, resulting in inaccurate monitoring data. Even if it is the same heavy metal pollution, it may also be due to different factory environments and different water quality characteristics. Different concentrations of substances will be applied to different monitoring schemes.
Targeting of the monitoring program, that is, providing targeted monitoring programs for different types of enterprises, pollutant concentrations, interference factors, etc. The most affected in the detection process is the interference of other heavy metals, such as: the detection of lead, mercury, such as iron, calcium, copper, zinc, etc., which has a greater impact. It is necessary to remove the interference factor and increase the pretreatment in the process of detecting the factor Or a corresponding masking agent to ensure the accuracy and validity of our monitoring data.
In summary, the heavy metal pollution in our country, whether it is water, air or soil, has reached a very serious point. Major accidents have occurred frequently, and the people in the polluted areas have been deeply affected. But the 12th Five-Year Plan of the Ministry of Environmental Protection has shown the country's determination to prevent and control heavy metal pollution.
Whether it is prevention or treatment, first of all, quantitative and qualitative analysis of the pollution degree and discharge status is required, and the independent analysis data is not representative and instructive, so continuous and effective data must be obtained in the entire system. Therefore, online monitoring and analysis instruments are one of the important means in the system.
The main indicators of analytical instruments are accuracy and stability, and the protection of these two indicators needs to be considered in terms of detection methods, product processes and component selection. The water quality monitoring and analysis instrument developed by Ankong Technology started technological innovation from these aspects, and finally fully satisfied the needs of the environmental monitoring field with its excellent performance and rich functions.
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