Team:SCUT/Visits
Discription
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.
PROJECT PHOTOS
