Difference between revisions of "Team:SCUT/Visits"

Visit Guangzhou Municipal Environmental Protection Bureau  

To gain more knowledge about the origins, kinds, and degrees of cadmium pollution and to receive professional evaluations and opinions, we invited engineers working in Guangzhou Environment Monitoring Center to hold a lecture for us and we discussed about our project with them comprehensively. 

The invited engineers were Chief engineer Wang, engineer Zhu and director Wu.

The contents of the lecture are: cadmium applications, origins of cadmium pollution, negative effects on humans, ways to stop cadmium pollution and so on.

Cadmium has wide applications, which results in many origins of pollution. Some kinds of alloy with low-melting-point include cadmium. Electrical contacts in electric switches mostly contain silver/cadmium oxide and widely used in household appliances and automotive relay.    And then, cadmium has moderate thermal capture cross section, cadmium alloy is used in reactor control rods. As compound, cadmium was widely used in pigment, stabilizer for plastics, fluorescent powder, insecticide, bactericide and oil paint. In addition, cadmium is used in rechargeable batteries such as nickel-cadmium battery, silver-cadmium battery. Cadmium sulfide and cadmium selenide are used in photocells.

From the information mentioned above, cadmium can be seen in our daily life. Cadmium pollution can be divided into three parts: atmospheric pollution, water pollution and soil pollution. Industrial manufacture dust emission results in atmospheric pollution, such as nonferrous metals smelting and calcining. Surface runoff and industrial effluents result in water pollution. Preparation of vitriol and phosphoric acid will let out waste water, which contains much cadmium. It can do great harm to the environment if it was let out randomly. Furthermore, cadmium is used in making plastic, pigment and accelerant, which may lead to water pollution. Lastly, soil pollution comes from using phosphate fertilizer and pesticide.

The main pollution is water pollution (waste water – soil – rice - humans). The speed of cadmium being expel from our bodies is very low. Cadmium’s biological half-life is 10 to 30 years in human renal cortex. When absorbed into body, it will become  cadmium metallothionein staying in kidney and liver, and poisons organs and skeletons. Epidemiology research shows that cadmium can cause teratogenesis and carcinogenesis (prostate cancer).

Treating cadmium pollution is a nichetargeting work. Different sample has different process, but chemical process and physical process are common processes.

For soil pollution, it’s supposed to use phytoremediation. For example, people usually plant arabis gemmifera which can absorb cadmium. In due time, they will be reaped, gathered together and handled. Sometimes people use solidification technology such as using cement to immobilize soil. If the polluted area is small, it’s suitable to use leaching method and weaken its activity after being immobilized.

For water pollution, it’s supposed to use chemical precipitation, IX, electroosmosis, membrane separation and so on.

For now, chemical process and physical process are widely used in heavy metal treatment. Wang told us, some laboratories are researching microbial treatment, such as extracellular adsorbing and intracellular accumulating. For example, cadmium can form protein-sh or amino acid complexes, sulfide precipitation. However, there are many problems. The main reason is the large difference between actual conditions and laboratory conditions, which may lead to different results. Temperature and pH are always different, so the microorganisms may die easily. In order to get better effectiveness, we should find out and transform tolerant bacteria.

After learning of our project, Wang thought highly of our project. Comparing to chemical substance primary input-cost, microorganisms are able to breed and achieve our goal. This is an innovation, not only can it reduce energy and substance, but also it saves money and time for us. Engineer Zhu put forward valuable opinion for our project. He also believed that we should improve the bacteria’s tolerance. Moreover, he suggested that we should pay attention to safety and recycling.

After the lecture, we visited their laboratory and Zhu showed us their instruments and achievements.

Through this significant visit and study, we learnt of the advanced technology used in dealing with waste water and heavy metal detection. More importantly, we realized our disadvantages and made improvements in the right direction. Thanks to their help and encouragement, we will be more active in improve our project. We believe that we can establish better technologies and methods in research and applications, and in turn, benefit the society with synthesis biology.

 

The interview in Shen Yang institute of automation academy of sciences

In other to explore the feasibility in reality of our project , we interviewed the expert in Shen Yang institute of automation academy of sciences in Guangzhou,China.

 

The note is below.

 

Q： What’s your method of dealing with sewage at present?

A： We usually take some activated sludge from the sewage treatment plants and dispose it.

 

Q:  Then what’s the general source of the sewage you treat with?

A:  It basically comes from electroplating factories and the printing industry.

 

Q:  So it means that heavy metal treatment makes up the majority.？

A:  Yeah, and we will probably take the treatment of organics, such as the agricultural organic waste water, into account.

 

Q:  Ok, now another question is, you haven’t done much about the transformation and the screening of the strains of the activated sludge, have you?

A:  No, but we definitely will do some research at this point latter and it’s just the early stage now.

 

Q： Then do you think our project can be used in the practical application?

A:   Many sewage treatment plants haven’t done any transformation yet. I believe that your program is a progress. Maybe a few years later, when the level of sewage treatment at home has grown, the research direction will turn to this point. But for now, there are still some problems about the cost and it will be a little hard to put it into practice.

 

Q： You just said that there was an instrument that could detect the illegal discharge of waste water and a machine that can do some real time monitoring. Could you explain something about it in detail?

A:  Well, it is the first product that can do real time monitoring of sewage at home. It used to cost us a lot of time to take examples by ourselves, which is inconvenient and low-efficient. Now by using this instrument, we can detect the situation of the target watershed more easily and with high efficiency. The instrument involved more than a dozen parameters, including the parameter of Cd²⁺ , so it can realize the detection of all-weather Basin.

 

Q:  Thank you very much.

A:  You're welcome.

 

After this interview , we found it is the main method ,which was using the activated sludge , for the company to deal with the sewage . Besides ,they were able to detect the illegal discharge of waste water and could do some real time monitoring by using a machine . They might do some research for the transformation and the screening of the strains of the activated sludge in order to improve the method of dealing with the organic waste water .Our technology has the function of both detection and metal adsorption of cadmium iron, and meanwhile， reduce the use of chemical materials，which is friendly to the environment.

 

 

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