Living with waste causes hurdles that become unbearable as time goes on. The resulting greenhouse gases such as methane, a significant drive to climate change, and some other artificial chemicals would leave a permanent mark in the atmosphere, contributing to the much feared air pollution. On land, an increase in cockroaches and rodents would increase land pollution, gradually causing health issues for nearby communities. The harmful effects of these natural and plastic wastes are a bane to society, and although the majority of students and individuals worldwide see and dislike these effects, not many can visualize how well these harmful effects could be curbed through a bit of chemistry and engineering.
Ideas for how to solve our waste problem come in various shapes — with various levels of effectiveness. The idea that some of this waste will eventually rot continues to thrive in some communities, with some individuals suggesting that all waste will eventually decompose, no longer presenting a problem. Of course, some waste does rot but the process isn’t in any way pretty or beneficial to the problem. All of this could be avoided and even reversed if we could just reduce the amount of waste but also convert it into something usable, something valuable, something better than risking environmental devastation.
As a student, I was fortunate to work with a team of engineers on obtaining valuable products from the waste of fruit (pineapple in particular) through a bit of fermentation, heating and distillation. Our goal was BIOMASS—fuel that is clean and sustainable enough to reduce pollution while providing alternative means of power compared to conventional fuels like fossil fuel.
Biomass is a renewable fuel derived from organic materials and acts as an alternative for producing fuels, heat and electricity. Converting these waste to biomass is essential in producing cleaner fuels and reducing the pollution these waste build.
We carried out a series of steps and chemical reactions before converting this waste to ethanol.The process of collection involved visits to any polluted environment with a significant amount of fruit waste in order to launch our experiment. We considered the amount of fruit waste to be a gauge of how high our ethanol yield would be.
Research, collection, and grinding
At first, gathering this waste could be unhealthy without taking into consideration proper measures. When working on this project, we used a nose mask to avoid inhaling the foul smell this waste produces, and gloves when gathering fruit waste.
To ensure maximum ethanol production, I worked with a group that researched the amount of alcohol in different fruits at different stages of decay. Ripe fruit waste usually contains more alcohol than their unripe counterparts, hence we used about 2.4kg of ripe pineapple waste retrieved from the waste site. We rinsed off excess dirt and germs with water in preparation for the home grinding appliance we later used to grind the peels.
Grinding this amount of waste mixed with 1.5 liters of water yielded small, moist chunks of pineapple waste which were separated by filtration in order to distinguish the solid chunks from the liquid. The resulting mixture was pure liquid which we termed “the filtrate.”
The filtrate was heated for about 3-4 hours in order to produce sugar. This sugar content was measured using a hydrometer. The sugar syrup is then diluted and fermented using Sacchromyces cerevisiae (yeast). Diluting the sugar is a practice performed to prevent the sugar from killing the yeast. 10ml of this yeast was added and mixed with 100ml of 37°C water, then stirred regularly for 10 minutes, before finally being allowed to sit for 3-4 days in a sealed container at room temperature. At intervals, the mixture was manually agitated to ensure proper mixing and fermentation of the yeast with the sugar.
During fermentation, our liquid produced heat through a gradual stirring process, which yielded alcohol. Research shows a 7-8% by volume ethanol production at 50-70 hours into fermentation, with some studies showing that an 80-100 hour fermentation would yield 8-9 % ethanol. This fermented product has alcohol present and while some use this for the well known Tepache recipe, our goal was ethanol production. With this in mind, our fermented product was heated and separated through fractional distillation, a technique used to separate mixtures of various boiling points.
Fractional distillation was only possible due to the difference in boiling points between the alcohol and water present in the fermented product. Definitely, the ethanol present would evaporate before the water due to its lower boiling point (about 78.37°C). The vapor passes through a copper pipe which is rapidly cooled and yields liquid as the end product (through condensation). This liquid is ethanol, although it could contain a bit of water if proper distillation wasn’t carried out.
From this experiment, we successfully reduced both air and land pollution in exchange for ethanol using fractional distillation, a biofuel that is ecologically effective and releases less carbon emissions when used in automobiles.
But there’s a catch: When reaching our desires for economic, social, and environmental sustainability, there needs to be a valuable and reasonable amount of input to yield the same reasonable amount of output. Unfortunately, this was not the case when producing ethanol from pineapple waste. Our experiment showed that from a 2.5 litres of fermented pineapple juice, we could only obtain about 0.05 litres of ethanol, which is much less than the required amount to even partially replace conventional fuels.
Continuing to work on producing ethanol with such low yields might mean the possibility of food shortage. The United States Environmental Protection Agency highlights that economic models reveal biofuel use can result in higher crop prices.
The large scale ethanol production process is by no means efficient yet and a huge amount of money invested in developing efficient means might also spike the ethanol distribution costs — opposing one of the most adored reasons for producing bioethanol: it’s cheap cost. Our already occupied land and environment would have to be cultivated with a huge amount of crops from which waste could be obtained in order to produce a reasonable amount of ethanol that rivals or completely replaces fossil fuels.
Our alarming need for transportation fuel alone rises daily, as explained by Tim Searchinger and Ralph Heimlich of the World Resources Institute in their working paper. Large fossil fuel consuming regions have established ambitious biofuel targets that amount to 10% transportation fuel by 2020. If such targets were to go global by 2050, using 30% of a year’s harvest today would only produce about 10% of the transportation fuel needed, making a sustainable food future more difficult.
We’d be sacrificing a valuable portion of the Earth’s soil to produce a somewhat minuscule amount of valuable biomass required to power our automobiles today. This cost makes the situation rather unwise for such an industrial project by large scale industries. Those same industries could emit large amounts of gases, causing minor water pollution. Although it’s still a debate, our pineapple waste experiment showed that we have not yet achieved the perfect alternative to fossil fuels we all wish for.
Our Sustainability cycle
There is irony in the fact that such a simply-made alternative to fuel introduces a new set of such serious problems.
The waste that resides in polluted environments is not enough to produce a desired amount of ethanol for powering vehicles, and yet to increase these wastes for higher yields is unsustainable as well. Using the Earth’s soil to cultivate crops not for food but instead solely for ethanol and BIOMASS production causes its own environmental damage, along with the social issues of acquiring the land and not feeding populations in need. But the experiment which was carried out shows that ethanol production and waste reduction are possible — if not on an institutional level, then at least on an individual one. We can’t produce enough ethanol sustainably for entire regions, but hobbyists could make biofuel for their own personal use and reduce pollution in their society at the very least, making it a rural-based humanitarian service for people deeply affected by environmental pollution.