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加拿大高中生发明快速分解塑料袋方法  

2008-07-12 00:55:46|  分类: 汽车 时尚 资讯 |  标签: |举报 |字号 订阅

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加拿大高中生发明快速分解塑料袋方法            资料来源:TheRecord.com

由于塑料袋造成的“白色污染”早已成为地球公害,因此它被称为“人类最糟糕的发明”。然而加拿大16岁的高中生丹尼尔·伯德通过研究,发现通过一种神奇的假单细胞菌,可以将塑料袋的自然降解过程缩短至3个月!

  做家务时产生灵感

  据加拿大The Record.com 报道,现年16岁的少年丹尼尔·伯德是加拿大安大略省沃特卢市一名高中生。他的研究理念来自日常生活的经历:他经常帮母亲做家务,但每当他打开存放洁具的柜子时,放在最上层的塑料袋就会如雪崩般飞散。烦不胜烦的他开始研究如何能令塑料袋“消失”。

  塑料袋的自然分解时间通常从20到1000年不等。但伯德认为,它始终会被微生物分解,所以只要找出可以分解塑料袋原料——聚乙烯的细菌,再将这些细菌集中便行了。在老师的指导下,他发现将绿脓杆菌和甲氰菊酯降解菌混合使用,将会令分解塑料袋的速度大大加快。这两种细菌均属于假单细胞菌,而伯德的研究是全球首度证明假单细胞菌可以分解制造塑料袋的原料——聚乙烯。

  



  只产生水和二氧化碳

  在实验过程中,伯德从当地一个垃圾场获取泥土样本,并将泥土样本跟聚乙烯和一些促进细菌生长的溶液混合。他将溶液浓缩多次及培养12个星期后,伯德试验培养液对塑料袋碎片的分解效果。结果,他发现上述两种细菌分解聚乙烯最为有效。

  随后,伯德分离出这两种细菌并混和醋酸钠,然后将温度调节至摄氏37度。他惊喜地发现,细菌在这样的环境下,6周内就能分解43%的塑料袋碎片。按照这个速度,伯德认为塑料袋只需3个月便可以完全被分解。伯德又测试了这个分解塑料袋的方法能否大规模应用,结果发现,只要好好控制温度,令细菌变得活跃,它们便能大量分解塑料袋,所需成本极低。分解过程中亦不会产生大量污染物,只会产生水和少量二氧化碳。

  申请专利挣大学学费

  虽然目前这项研究仍然处于实验阶段,但伯德已经有更长远的想法:他希望能够为此申请专利,将这种技术打进市场,并通过出售专利挣够学费,然后攻读一所理想的大学,以便继续从事科学研究。日前,被誉为“塑料袋克星”的伯德在“全加拿大科学展”上勇夺第一名,并且获得3万美元的奖金。目前,他已经得到多所大学的奖学金。

WCI student isolates microbe that lunches on plastic bags                     TheRecord.com 

Daniel Burd's project won the top prize at the Canada-Wide Science Fair in Ottawa. He came back with a long list of awards, including a $10,000 prize, a $20,000 scholarship, and recognition that he has found a practical way to help the environment.

Daniel, a 16-year-old Grade 11 student at Waterloo Collegiate Institute, got the idea for his project from everyday life.

"Almost every week I have to do chores and when I open the closet door, I have this avalanche of plastic bags falling on top of me," he said. "One day, I got tired of it and I wanted to know what other people are doing with these plastic bags."

The answer: not much. So he decided to do something himself.

He knew plastic does eventually degrade, and figured microorganisms must be behind it. His goal was to isolate the microorganisms that can break down plastic -- not an easy task because they don't exist in high numbers in nature.

First, he ground plastic bags into a powder. Next, he used ordinary household chemicals, yeast and tap water to create a solution that would encourage microbe growth. To that, he added the plastic powder and dirt. Then the solution sat in a shaker at 30 degrees.

After three months of upping the concentration of plastic-eating microbes, Burd filtered out the remaining plastic powder and put his bacterial culture into three flasks with strips of plastic cut from grocery bags. As a control, he also added plastic to flasks containing boiled and therefore dead bacterial culture.

Six weeks later, he weighed the strips of plastic. The control strips were the same. But the ones that had been in the live bacterial culture weighed an average of 17 per cent less.

That wasn't good enough for Burd. To identify the bacteria in his culture, he let them grow on agar plates and found he had four types of microbes. He tested those on more plastic strips and found only the second was capable of significant plastic degradation.

Next, Burd tried mixing his most effective strain with the others. He found strains one and two together produced a 32 per cent weight loss in his plastic strips. His theory is strain one helps strain two reproduce.

Tests to identify the strains found strain two was Sphingomonas bacteria and the helper was Pseudomonas.

A researcher in Ireland has found Pseudomonas is capable of degrading polystyrene, but as far as Burd and his teacher Mark Menhennet know -- and they've looked -- Burd's research on polyethelene plastic bags is a first.

Next, Burd tested his strains' effectiveness at different temperatures, concentrations and with the addition of sodium acetate as a ready source of carbon to help bacteria grow.

At 37 degrees and optimal bacterial concentration, with a bit of sodium acetate thrown in, Burd achieved 43 per cent degradation within six weeks.

The plastic he fished out then was visibly clearer and more brittle, and Burd guesses after six more weeks, it would be gone. He hasn't tried that yet.

To see if his process would work on a larger scale, he tried it with five or six whole bags in a bucket with the bacterial culture. That worked too.

Industrial application should be easy, said Burd. "All you need is a fermenter . . . your growth medium, your microbes and your plastic bags."

The inputs are cheap, maintaining the required temperature takes little energy because microbes produce heat as they work, and the only outputs are water and tiny levels of carbon dioxide -- each microbe produces only 0.01 per cent of its own infinitesimal weight in carbon dioxide, said Burd.

"This is a huge, huge step forward . . . We're using nature to solve a man-made problem."

Burd would like to take his project further and see it be used. He plans to study science at university, but in the meantime he's busy with things such as student council, sports and music.

"Dan is definitely a talented student all around and is poised to be a leading scientist in our community," said Menhennet, who led the school's science fair team but says he only helped Burd with paperwork.

Other local students also did well at the national science fair.

Devin Howard of St. John's Kilmarnock School won a gold medal in life science and several scholarships.

Mackenzie Carter of St. John's Kilmarnock won bronze medals in the automotive and engineering categories.

Engineers Without Borders awarded Jeff Graansma of Forest Heights Collegiate a free trip to their national conference in January.

Zach Elgood of Courtland Avenue Public School got honourable mention in earth and environmental science.

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