Finding and removing microplastics from water.

Latest update August 21, 2019 Started on January 1, 2018
land
sea
backyard

I want to find a new method to remove microplastics from water and explore how to implement this in the environment.

Preparation

More field work to come!
I am looking foreward to do more analysis and surveying of our coast. I wish to find out the main types of microplastics in our seawater. For this I will paddle around our coastline, take water samples and dive to look at the plastics on the bottom. In addition to this, I am working on designing a prototype which I could use for micrplastic estraction in wastewater where it enters the sea.

All I need to do now is wait for good weather.

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Now comes phase two of my project. That is, implementing it in the real world. I need to build a prototype to make this into reality. Make a prototype which could be applied in wastewater treatment and water cleaning.
This is what I am working on and this means that I am going back to the drawing board! Ill keep you updated!

I will stay tuned! Inspirational work
Debriefing

The following is a list of conclusions I have drawn from my experimental results:


The overall results, taking into account results from both spectroscopy and microscopy and taking into account the various volumes of oil added (if any), show that the average quantity of microplastic extracted using these methods is 87.6% ±1.11%. Spectroscopy alone produced a result of 85% ± 0.92% and the overall result for microscopy was 90.5% ±1.38%. From this, I can conclude that my hypothesis is not rejected with 95% confidence. i.e. my extraction method will remove 85% or higher of the microplastics in my samples. For each plastic tested, the quantity of plastic removed was greater than 85% apart from Polypropylene which had an average reduction of 80% ± 3.07% (95% confidence). The method was most effective for the plastic fibres extracted from the washing machine filter with an average reduction of 95% ±2.3% (at 95% Confidence) and HDPE plastic with an average reduction of 91% ±3.1% This shows that this method would be very useful in urban wastewater treatment plants, as over 55% of plastics in wastewater originate from washing machines and clothes 11. On average, the tests with 12.5 ml oil/L water gave higher plastic reduction rates than tests without any oil added (magnetite only). However, the t-test carried out on these results showed no statistically significant difference. From this I can conclude that using magnetite with a minimum of oil forms a viable method for the extraction of microplastics. If this method is to be applied in wastewater treatment, I believe that it is important to minimise the amount of oil and magnetite used to make the extraction more economical while using enough to ensure the maintain high extraction rates to maximise plastic reduction. There is no doubt that the most effective way to reduce microplastic pollution in oceans is to use less plastics and ensure that plastics used can be recycled and separated to prevent them from entering our wastewater, but the reality is that more and more of the products we use contain plastics and potentially degrade into microplastics before entering our wastewater. It is therefore essential that we find efficient and effective ways of extracting microplastics from wastewaters before they reach our watercourses and ultimately our oceans. Once plastics enter our oceans, they are practically impossible to extract. The results of this project show that this could be a viable method. However questions remain to be answered. This project only forms the very beginning of this extraction idea which has never been conducted before. Further research needs to be carried out to investigate the efficacy of various grades of magnetite, different types of magnetic systems, methods for separating the waste and the design of a system that could be introduced into treatment centres.

RESULTS


10 different types of microplastic suspensions were tested. 3 extractions were carried out for each of the 4 different volumes of oil used in each extraction. To obtain a meaningful result, for each extraction, 50 spectrometer captures were carried out and 3 microscope captures were done. 120 captures in total were taken for every extraction. From these, means and standard deviations were calculated which allowed the further calculation of standard error and a final hypothesis test.

The results can be seen in the graph attached below:

From this graph, you can see that the average extraction percentage was 87% This is a very good result and I am please that this method has proved sucessful at this stage!

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In The Field

I'm doing loads of tests at the moment and just decided to also add my home built microscope as a testing method as well. I think that it will allow me to have an auxiliary testing method just in case my spectrometer is not accurate enough. I will use adobe photoshop to count the pixels visible on microscope images of the water before and after extraction. I think that this will work well to get a % decrease in plastics in the extraction.

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Yay! I'm finally doing tests to see how efficient my method really is!
Attached is a schematic diagram (it was not possible to upload it to open explorer so you can find it here: https://drive.google.com/open?id=1VVmbQA5lfzwWpmypRKtfBxnTFC65ylp ) of my testing method which I used for all of my samples. I plan to test each plastic type with 4 extractions and at 4 different concentrations of oil. I plan to repeat each extraction 5 times for accuracy. This gives an average of 600 tests per plastic type. This should be a large enough n for statistical analysis!

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After loads of experimentation and failed tests, I have built a machine to measure the concentration of microplastics in water. It is a visible light spectrometer and it's diagrams are shown below. I have obtained correlation coefficients of over 98 in my tests which shows how accurate it is. I can analyze samples by using the Beer Lambert law. I scan in the concentrations of known concentration samples and like this find out the concentration of unknown samples using a calibration curve which I set up and made.


Now I need to start proper testing!

After creating these 10 different types of microplastics, I decided to test them using a testing method of constant volumes and tests to make tests fair and accurate.


I did, however have one problem. I could not find a suitable method to test the efficiency of this extraction process. I've tried using a turbidity meter and a light but results are not accurate. I have been looking around for a lab who test for microplastics to no avail. If I want to test how efficient and effective my microplastic removal method is, I will need to build my own equipment.

That is why, I have started to build with my limited materials. I'm thinking about building equipment such as a photometer that will shine light through my sample and measure what comes back. Like this I can measure how much is being absorbed by the plastic. I am also contemplating using a microscope.

I've started building using wood, foamboard, an Arduino microcontroller and a couple of other bits too.

I tested this method many more times and it worked!
Now I need to do it on more types of plastic. I decided to start making microplastics from the 10 most commonly found microplastics on our shores. Namely: PET, HDPE, LDPE, PVC, PP, PS, Nylon and Polyester.

I decided to make these using different methods including sanding them!

I recently read an article by a scientist, Dr Arden Warner. He cleans up oil spills using Magnetite (iron oxide / rust powder). It basically makes a ferrofluid with the oil. I think this is an interesting idea and think that it could be easily applied on my extraction method for microplastics from water.


I did a couple of tests of this, and found that this method works to remove bot the plastic particles and the oil. Maybe this could form the basis for a new extraction method. One of these tests is shown in the video below.

It starts with a suspension of microplastics in water. Vegetable oil and magnetite powder are added forming a magnetic ferro-fluid. Magnets are brought close and these remove the oil, magnetite and plastics too.

I'm excited to do some more tests!

After realizing that vegetable oil attracts plastic particles, I have done many tests where I add vegetable oil to water containing microplastics. In many of these the microplastics got stuck in the oil. Now the question just remains how to extract the oil from the water. Surely there must be an interesting method to do this efficiently.

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While surveying and exploring our coastline, I found a rock with oil spill residue on it. It had lots of little plastic particles stuck to it and this, got me thinking!


In chemistry class, I learned that likes attract likes when talking about chemical polarity. Oil is non-polar and so is plastic. This is why they stuck together. I thought that this might be something interesting. I researched further and found out that vegetable oil, too was non-polar. I understood that vegetable oil would stick to plastic particles. This was a true point of revelation as I actually had my first ideas about removing microplastics from water.

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Preparation

To start my expedition, I needed to find out how many plastics were out there and also what type. Over the year of 2018 I paddled to over 1500 beaches and coastal areas in Roaring water bay, West Cork Ireland. I took sand and gravel samples from the sores and brought them back home to be analyzed in my home laboratory.


To do this, I had to build my own equipment and built a microscope for analyzing water and sand samples. This produced accurate results when testing for microplastics.

I found out that the 10 most common types of microplastics in our waters are: PET, LDPE, HDPE, PP, PS, Nylon, PVC, Polyester and washing machine conglomerate. These were the plastics which I decided to focus on for further testing and analysis as these were most persistent in our environment.

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To find out how big of an issue this microplastic pollution is, I've decided to look on my coastline. I plan to paddle from beach to beach taking sand and gravel samples to analyze at home under a microscope. Maybe like this, I can find out what the most common microplastics are and like this focus on these for my extraction experiments.

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Expedition Background

I live near the seashore in West Cork, Ireland and have become increasingly aware of plastic pollution of the oceans. after conducting tests in my environment from my home built lab, I was alarmed to find out how many microplastics enter our wastewater system and consequently the oceans. This inspired me to try and find out a way to try and remove microplastics from waters.


To find a method like this, I did lots of research. I found that there is currently no method to remove microplastics from wastewater without very time intensive and inefficient carbon filtration.

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This is such a great expedition and project, Fionn. I'm looking forward to following along with your progress.

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