Team:BEAS China/Description
Description & Inspiration
Heavy metal pollution in water bodies is a human-caused environmental issue that many governments and institutes tried to deal with.
The rapid growth of the global economy and associated technological progress has caused increased environmental concerns recently. Heavy metals are among the most problematic pollutants as they are non-biodegradable and can accumulate in ecological systems. In cases concerned with food chain systems, they will eventually result in food chemical contamination, which can lead to various diseases, threatening public health.1
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The distribution of heavy metals depends not only on the proximity to emission sources but also on the media being assessed. Sources of heavy metal pollution include wastewater with excessive heavy metals produced by heavy industry enterprises, waste lead-acid batteries not centrally processed, urban garbage, domestic sewage, and soil contaminated by heavy metals. According to a nationwide water quality survey, water from only 64.2% of the river sections, 58.8% of the major lake areas, and 23.2% of the ground water wells met the national drinking water quality standard.7 According to the survey, more than 80% of rivers, lakes, and seas in China are facing severe problems of heavy metal pollution, especially Cd, Hg, and Pb.2
The modelized distribution of (A) As (B) Cd (C) Cr (D) Hg and (E) Pb in China. (Huixuan Li et al., 2015)
Current methods to DETECT heavy metal pollution in water bodies and their limitations
To understand current detection methods for heavy metal pollution, we distributed a questionnaire and visited a Water-testing Station. The methods we investigated include inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma-atomic/optical emission spectrometry (ICP-AES/OES), energy dispersive X-ray fluorescence (EDXRF), electrochemical methods, electrothermal atomic absorption spectrometry (ETAAS), flame atomic absorption spectrometry (FAAS), and atomic absorption spectrophotometry (AAS).3
Most of these techniques are of high sensitivity, specificity, and precision. However, all of them are expensive and require elaborate apparatuses, professionals, and complex operations.4
Thus, a simple, cost-effective, and portable detection method is highly demanded, especially in developing countries and areas, which lack of sufficient infrastructure, professional experts, and appropriate environmental treatments.
Current methods to TREAT heavy metal pollution in water bodies and their limitations
As for the treatment, we have also distributed a questionnaire and made a survey with a water-purification station. And we found that several strategies can be used to remove heavy metal cations from liquid media such as chemical precipitation, coagulation-flocculation, membrane filtration technologies, ion exchange and electrochemical methods. The following table summarizes the advantages and disadvantages of different processes.5
Table Comparison of advantages and disadvantages of different treatment techniques for heavy metal laden liquid media (João P. Vareda et al., 2019).
In summary, all current methods shared several disadvantages such as high cost and secondary pollution. Therefore, a cheap and efficient method to treat heavy metal in water bodies is still highly demanded.
Bioremediation methods to treat heavy metal pollution in water bodies and concerns
Bioremediation is gradually being accepted as a standard practice for the treatment of water heavy metal pollution since it is more eco-friendly and cost-effective compared to the conventional chemical and physical methods, which are often very expensive and ineffective when metal concentrations are low, in addition to producing significant amounts of toxic by-product.6
However, there is one big concern about that applying biotechnology to solve real-world issues is bio-contamination. We have distributed a questionnaire to address public concerns about biotechnology application, and we found that there is still a considerable proportion of people(37% from our data) doubts or disagrees to use biotechnology, and 43% of them possess this negative attitude due to the concern of danger that may be brought out by biotechnology.
Given the public concerns about bio-contamination, a safety controller is necessary for the bioremediation methods for heavy metal pollution treatment.
Therefore, heavy metal pollution in water bodies is still a serious issue requiring a better solution. Several iGEM teams focused on this problem before. However, through surveying previous projects, we found that a comprehensive solution for the water heavy metal pollution is in urgent. Thus, we come up with the idea to provide a silver bullet to both detect and collect heavy metal pollution from wastewater. To accomplish this goal, we designed and modified microbes to create a Modularized & Smart & Safe Machine for Heavy Metal Bioremediation, containing three modules: detector, catcher and safety controller.
References
1. Tak H.I., Ahmad F., Babalola O.O. (2013) . Advances in the application of plant growth-promoting rhizobacteria in phytoremediation of heavy metals. Reviews of Environmental Contamination and Toxicology. Volume 223.
2. Sun WF, Xiao D.(2012). Status and Control Technology of Heavy Metal Pollution. Energy and Energy Conservation. Volume 77.
3. Lin Y, Gritsenko D, Feng S, Teh YC, Lu X, Xu J. (2016). Detection of heavy metal by paper-based microfluidics. Biosens Bioelectron. Sep 15;83:256-66.
4. Lin Cui, Jie Wu, Huangxian Ju. (2015). Electrochemical sensing of heavy metal ions with inorganic, organic and bio-materials. Biosensors and Bioelectronics. Volume 63.
5. João P. Vareda, Artur J.M. Valente, Luisa Durães. (2019). Assessment of heavy metal pollution from anthropogenic activities and remediation strategies: A review. Journal of Environmental Management. Volume 246.
6. Ojuederie, O. B., & Babalola, O. O. (2017). Microbial and Plant-Assisted Bioremediation of Heavy Metal Polluted Environments: A Review. International journal of environmental research and public health, 14(12), 1504. doi:10.3390/ijerph14121504
7. Huixuan Li, Yingru Li, Ming-Kuo Lee, Zhongwei Liu and Changhong Miao(2015). Spatiotemporal Analysis of Heavy Metal Water Pollution in Transitional China. Sustainability,7(7), 9067-9087.