Rethinking Your Garbage

garbageDo you ever wonder what happens to your garbage after you throw it out? While we hope that the recyclable materials we painstakingly sorted out end up being recycled, the garbage usually ends up sitting in the landfill. Although the landfill may be a solution for our “throwaway” society, it isn’t quite a permanent one. Think about how the increasing population on the planet will directly increase the amount of garbage produced, and how land is a precious commodity. As the time increases, the amount of land available will decrease, and 2/3 of the Earth is covered by water anyway. With global warming, more land may become submersed. The ocean isn’t immune to garbage either, as much of it, especially plastic waste, ends up polluting the precious sea life and the water.

According to the Conference Board of Canada, Canada produced 777 kg per capita of municipal waste in 2008. In a study ranking the municipal waste generation of 17 countries, Canada ranked last, meaning that Canada produced the most garbage per person. What’s worse is that Canada’s municipal waste production has been increasing since 1990.  The Conference Board of Canada further states that Canada should learn from other countries such as Japan, the U.K., Sweden, Finland, and Denmark in order to improve their municipal waste management.

Sweden has found a solution in which less than 1 percent of household garbage (municipal solid waste) ends up in landfills, and 99% of the waste is recycled. This is a drastic improvement, since only 38 percent of Swedish household waste was recycled in 1975. How does Sweden do this? First, the Swedes take their recycling very seriously, and recycling stations are situated, “as a rule”, according to Swedish website, no more than 300 metres from any residential area. The garbage that can’t be recycled is incinerated for energy at their 32 specialized waste to energy incineration plants. In 2012, for instance, 2,270,000 tonnes of garbage was incinerated for energy. Sweden also imports 700,000 tonnes of waste from other countries, at a profit, and turns this foreign garbage into energy too.
“Waste to energy”  is the generation of energy, such as electricity and heat, from household garbage (municipal solid waste). Modern waste to energy incineration plants in OECD countries, including those in Sweden, must meet rigid emission guidelines pertaining to levels of toxic emissions such as those of nitrogen oxides, sulphur dioxide, heavy metals, and dioxins. The waste to energy plants utilize furnaces which are fed garbage. The garbage is burnt, producing heat which boils water and generates steam. The steam powers generator turbines that can then produce  electricity and heating. The electricity is distributed across the country. And just like that, in Sweden, 810,000 households are furnished with heating and 250,000 with electricity.

 While Swedish citizens overall don’t seem to be complaining about waste incineration, some people point out that the toxins leaked into the air can be unhealthy for the environment.  Even though emission levels of toxins are controlled for, modern incinerators can still emit small amounts of heavy metals, dioxins, particulates, and acid gas in the fly ash.  Lime scrubbers and electrostatic precipitators are put on smokestacks to filter the smoke and prevent acid rain, while fabric filters, reactors, and catalysts also significantly work on limiting the amounts of released pollutants. Aqueous ammonia can be used to control for the amount of nitrogen oxides, and carbon can help control for the amounts of mercury. Phosphoric acid can be administered to counterbalance the ash.

When it comes to greenhouse gases, methane gas is 21 times more harmful to the environment than carbon dioxide. Landfills in Canada generate a staggering 20% of  the nation’s total methane production. According to Environment Canada, about 27 megatonnes of carbon dioxide equivalent are produced each year from Canada’s landfills, out of which 20 megatonnes of carbon dioxide equivalent are released into the environment annually. About 7 megatonnes of carbon dioxide equivalent are captured from landfills through a gas collection system, and combusted- this has the equivalent effect of taking 5.5 million cars off the road. Much of the carbon dioxide is not captured from landfills. There is also concern that landfill sites are filling up fast, and new sites are increasingly more difficult to find.

Canada needs to step up its waste to energy game. At present, the nation has only 7 waste to energy plants. They are located in Burnaby, BC; Quebec City, QC; Levis, QC; Iles de la Madelaine, QC; Brampton, Ont; Charlottetown, PEI; and Wainright, Alta. The waste to energy plant in Burnaby, BC, for instance, has been successfully operating since 1988. It produces a sufficient amount of electricity to power 16,000 households, earning Metro Vancouver about $6 million from the sale of electricity. About 8000 tonnes of metals are recovered each year, which earns the city $500,000 annually from the sale of recycled metal. More waste to energy plants should be built in Canada in order to divert the nation’s abhorrent trend of landfilling.

New waste to energy technologies are emerging which are even more exciting alternatives to landfills because these don’t require direct combustion, thus preventing fly ash and reducing the amount of bottom ash.  Conversion technologies involve the heating of municipal solid waste at superheated temperatures in an oxygen-controlled environment to deter combustion. Solid waste is converted to usable products such as synthesis gas, which is mainly made of hydrogen and carbon monoxide. This “syngas” can be burned in a boiler to generate electricity, or be processed into a fuel.  In a few years from now, more affordable technology could allow this syngas to be cleaned and purified of contaminants, allowing conversion technologies to become an efficient and cleaner alternative to combustion incineration. Newer technologies do not produce as much bottom ash, a toxic byproduct, as incinerated waste does. 40% of bottom ash produced by incinerating garbage is thrown into the landfill, and 60% of it is further processed to salvage metals. Conversion technologies can collect metals right away, and leave less byproduct to dump into the landfill.

When I think of landfills, I am often reminded of the scene in Idiocracy where the garbage in their landfill is piled up so ridiculously high that it collapses very dramatically. The image serves not only as a direct parable, but as a metaphor too. As the human population increases, so will the amount of garbage produced. Canada is generally known as a progressive country with a high standard of living. As a proud Canadian, I would love to see Canada find a good solution for the management of the population’s garbage.

Sierra Delarosa

 

 

 

 

Bacterial heroes and viral villains – snipping the way to the future

spider man By: Emily Brown, PhD

The most recent Spider-Man film grossed nearly $800 million worldwide, and cinemas are set to unleash a new and improved Spider-Man 2 this May. Whilst the great charm and beauty of actors Tobey Maguire and Kirsten Dunst most likely helped fuel the initial success of the film series, our fascination with the part-man-part-beast concept has spanned far beyond the glitter of Hollywood. Peter Parker’s DNA may have flashed before our eyes as his body assimilated superhuman powers, but the idea of genetic modification existed in both the fantasy and real worlds long before the advent of such impressive computer generated images. Wikipedia, arguably the source of all valuable knowledge, lists 85 characters, comics or films that involve some form of genetic engineering. Ranging from the less suspecting (Tracy Strauss, Madelyn Pryor, Julian Bashir) to the more ridiculous (Shaggy Man, Venus Bluegenes, The DNAgents), these characters share in common a possession of extraordinary powers, and sometimes the adoption of highly colourful and figure-hugging body suits.

But how exactly is the acquisition of such power explained by the respective literary proponents? Peter Parker’s body-wide changes are initiated by radioactive mutagenic enzymes present in the venom of the lethally irradiated spider un(fortunate) enough to bite him. Not long after this bite does Parker start to display spider-like characteristics -superhuman strength (the jumping spider can for example hold 170 times its own body weight), reflexes, balance, a subconscious sense of danger (the so-called ‘spider-sense’) and the ability to cling to any surface. No doubt all highly desirable traits. But as unlikely as this might sound, the suggestion that enzymes can alter DNA is not such a wild idea. Genetic modification, the direct manipulation of an organism’s DNA, requires the DNA to first be cut so that it can then be joined or spliced together with DNA from another source. A restriction enzyme is an enzyme that cuts DNA at or near specific recognition nucleotide sequences, known as restriction sites. These ‘molecular scissors’ are routinely used for DNA modification in laboratories and are a vital tool in molecular cloning.

Over 3000 restriction enzymes have been studied in detail, and more than 600 are available commercially. Whilst the idea of an irradiated spider might seem far-fetched, restriction enzymes are naturally found in bacteria and archaea (a group of single-celled microorganisms). Here they provide a defence mechanism against invading viruses; the foreign viral DNA is cut up by the restriction enzymes, while the host DNA is protected by an enzyme that modifies the DNA and blocks cleavage. The term restriction enzyme originates in fact from the studies of phage l (a virus that infects the bacteria Escherichia coli, better known as E. coli). In the early 1950s, in the laboratories of Italian scientists Salvador Luria and Giuseppe Bertani, it was discovered that a phage could grow well in one strain of bacteria, yet fare significantly worse in another. In the latter case, the bacterial host cell was evidently capable of reducing the biological activity of the virus (in a process known as restriction), although the exact mechanism remained unclear. This mystery was solved in the 1960s, this time in the laboratories of Werner Arber and Matthew Meselson, where it was shown that the restriction is caused by enzymatic cleavage of the phage DNA. Unsurprisingly, the enzyme involved was termed a restriction enzyme.

The restriction enzymes studied by Arber and Meselson were type I restriction enzymes that recognise a restriction site, but cleave the DNA at a non-specific point located some distance away. Another decade later, in 1970, Hamilton O. Smith, Thomas Kelly and Kent Welcox isolated and characterised the first type II restriction enzyme, HindII, found in the bacteria Haemophilus influenzae. This type of restriction enzyme differs in that it cleaves DNA at the restriction site, and in doing so serves to be much more useful in the laboratory. Cohesive end cutter type II restriction enzymes cut the two DNA strands (most DNA molecules are double-stranded helices) at different points within the restriction site. The result is a staggered cut that generates a short single-stranded sequence or overhang, known as the sticky or cohesive end. These overhangs become very useful in genetic engineering, since the unpaired nucleotides that make up the sticky end can pair with other overhangs made using the same restriction enzyme. If DNA from two different sources are cut with the same enzyme, it is highly probable that the two DNA fragments will splice together because of the complementary overhang. The product is a recombinant DNA molecule, composed of DNA from two different origins, created by DNA technology.

Since the first discovery of restriction in the 1950s, the use of recombinant DNA technology has become commonplace, as new products from genetically altered plants, animals and microbes have become available. In 1997, Dolly the sheep dominated the headlines as the world’s first animal to be cloned from an adult cell. Whilst her early death may have left some scientist ‘wooly’ on the cloning issue (thanks to Jim Giles and Jonathan Knight for this clever pun), the technology has since gone on to bring advances to various areas of life, from treatments for cancer to transgenic insect-resistant crops. As far as is known however, we are yet to see the technology confer super-human strength and power. Thankfully we are not currently at risk of encountering deadly villains and their counterpart heroes on a daily basis, sporting their ridiculous costumes and egos. Instead, we are surrounded by the unseen heroes, the special enzyme molecules that battle to fight invading viral villains, and the scientific geniuses that brought them to light. Mr Muscle may argue that bacteria are best destroyed, but we should also thank these microorganisms for opening a whole new realm of our world, whatever that world may hold.

Emily Brown, PhD

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