Team:Worldshaper-XSHS/Background.html
In recent years, the water pollution is getting sever due to the lack of management in China.On May 29th, 2007 in Wuxi, Jiangsu Province, residents found that the quality of their tap water at home worsened overnight accompanied by an unpleasant smell, becoming not suitable for the regular needs. The source of their tap water was from Tai Lake. The sudden change of water is caused by the lowest water level of Tai Lake of the last 50 years, coupled with the continuous high temperature and little rain and the eutrophication of Tai Lake, triggering the cyanobacteria outbreak in advance. This had a direct result of the panic purchasing of pure water and large fluctuation of barreled purified water.
Here comes another case. At 3 PM on July 2nd, 2007, the ground water plant in Shuyang, Jiangsu found that the sewage had increased in a short time and penetrated into the intake along the Huaishu River. The content of ammonia nitrogen in water is about 28 mg per liter, which is far beyond the national water quality standard. More than 200,000 people’s daily lives are affected.
Hangzhou is a famous city in China, featured by the West Lake as well as The Grand Canal. It is known to all for its graceful water for thousands of years. In recent years, however, its water pollution the water pollution in this city is pushed forward. The China’s water treatment new policy brought up by the government has successfully recalled people’s passion to protect the water environment. But most of the conventional methods to monitor the quality of water are complicated and difficult to operate.
West Lake
When coming to monitor the concentration of dissolved oxygen, ISE and Volume titration are two main choices. An ion-selective electrode (ISE), or a specific ion electrode (SIE), is a transducer (or sensor) that converts the activity of a specific ion dissolved in a solution into an electrical potential. Volume titration acquires quite a few steps and different reagents as well. There are no fewer steps when monitoring the concentration of total nitrogen and phosphorus comparing to the ones for oxygen. All these add up to a result of difficulty in transporting and being short of timeliness. The measuring would be either too dumb or too expensive.
1.National standard method:
The national standard method uses pressure steam sterilizer or civil pressure cooker, the digestion is not only time-consuming and unstable, but also carries the safety hazard. What’s more, the temperature is difficult to control.
Compared with the national standard method, the determination results no significant differences, and it shows high degree of automation, which can achieve fast, accurate and sensitive determination of total nitrogen in water. The method meets the determination of low concentration of high quality water, also the industrial pollution sewage. The disadvantage is that the reaction requires high temperature and high energy. Because of using microsyringe, the water samples must be filtered out to remove the suspended material, so the nitrogen in the suspended matter cannot be detected and the results are lower.
3.Potassium persulphate oxidation- ion chromatography
Ion chromatography is difficult to popularize in general laboratory because of its high cost and high operating conditions
4.Microwave digestion - electrode method
The combination of microwave seal digestion and nitrate electrode method, It has the characteristics of quick, easy operation, precision and accuracy, which improves the analysis efficiency.
5.On-line digestion flow injection spectrophotometry
This method analysis of total nitrogen determination in water speed (1 hour) 40 samples, low detection limit, high precision and accuracy, and high automation level, has significant advantages in environmental water samples mass detection.
1.National standard method 2.ICP-AES
The ICP-AES method is used to enhance the sampling signal by axial side light, reduce the background interference, improve the sensitivity and SNR, and have the advantages of wide linear range, convenient, fast and accurate. Because of the pre-treatment of samples, each sample needs to be resolved and the workload is relatively large.
3.Digital Imaging Colorimetry
The method is convenient, quick and suitable for field analysis.
4.Ultraviolet photocatalytic oxidation – spectrophotometry
This method can be carried out at the normal pressure and low temperature, which can reduce the heat resistance and compressive load of the decomposing vessel, reduce the determination cost, and do not produce secondary pollution. However, it is difficult to apply the method and the recovery rate is low.
1.High pressure – Potassium persulphate digestion
The method can reduce the sample usage by 50% and reduce the time of digestion by 50%, simplify the operation step, reduce the labor intensity, achieve the effect of fast, time-saving and labor-saving, and improve the monitoring efficiency.
2.Microwave - hydrogen peroxide digestion 3.Microwave irradiation injection spectrophotometry
Combined with microwave digestion and flow injection, it is not only safe, easy to operate, but also saves reagents, accuracy and precision.
4.UV photocatalysis - potassium persulfate oxidation spectrophotometry
The advantage of this method is that it can be carried out under normal temperature and pressure.
The determination methods of the concentration of oxygen, total nitrogen and total phosphorus are various, while some of them are not easy to operate and are high-cost. Hence, we hope to provide an easy-operating and low-cost tool for public to monitor water quality around.
Background
