Define:

Our problem was that we had to design a filter that would filter the waste water we were given so that it would be suitable for life in the Pitt River. We had to do this with the materials provided and we had to clean the water by filtration, meaning we weren’t allowed to boil the waste water or use any other techniques. We also had to construct our filter in the space of a 2 liter pop bottle.

Discover:

I used the sites below to learn more and add context to our problem. The first source gave me information about how agricultural runoff can be polluted. This was helpful because it gave me an idea of what could be in our waste water that we must find a way to filter out.From this site I determined that there could be sedimentation, pesticides and excess nutrients in the waste water. The second site provided information on how sand and gravel filters can work. This was helpful because sand and gravel were both on our list of supplies. The third site informed me how to remove chemical pollutants, specifically ammonia. At first this site didn’t seem helpful as the ways to remove chemicals it provided did not work with our list of materials, but it gave me ideas of how to improve my filter if I didn’t have restrictions.

https://www.epa.gov/sites/production/files/2015-09/documents/ag_runoff_fact_sheet.pdf 

https://www.who.int/water_sanitation_health/wastewater/FLASH_OMS_WSHH_Guidance_note4_20100729_17092010.pdf 

http://www.purewateroccasional.net/wtiammonia.html

Dream:

My group came up with a few ideas of how we could solve our problem. We first came up with an idea of what materials we wanted to include in our filter. The first material we all agreed we wanted was to use activated carbon. We also had the idea to put a sponge in the spout of the pop bottle. My group decided we wanted to put the objects in our filter from coarsest to finest, so that as the water moved down the materials would get smaller and smaller. Our group was afraid that the sponge might come out of the spout because of the weight of the materials above it, so we used a cheesecloth to secure it in place. Our first prototype, from top to bottom, consisted of gravel, polyester floss, sand, activated carbon, filter paper, sponge and cheesecloth. Later on in the process we changed the gravel to lucite beads, and added cotton balls at the top. Our final design, from top to bottom, was cotton balls, lucite beads, polyester floss, sand, activated carbon, filter paper, sponge and cheesecloth

Deliver:

Using our final design from our brainstorming, we constructed our filter with the materials provided from our teacher. Our teacher also provided us with a sample of waste water.

Before filtration the waste water sample had the consistency of water. It was a murky yellow mixture containing what appeared to be dirt. The waste water smelled of vinegar and ammonia. It was also acidic and had a pH of 4.

 

 

When we filtered the waste water we noticed that dirt and large debris were being filtered by the cotton balls. The water that came out of our filter was clear.

 

 

 

After we filtered it the water was clear although it was slightly cloudy. The water still smelled like vinegar and ammonia. The waters pH did not change and was a pH of 4.  

 

Debrief:

Areas of success:

I think our filter was quite successful when you take all the factors and limited materials into place. Our filter removed all of the dirt and debris in our waste water. Our filter was also able to remove the yellow colour and the majority of the murkiness. I think the colour and murkiness was caused by fine particulate matter, commonly known as sediment.

Challenges encountered:

While we were successful in some areas there were some things that our filter was not able to remove. Our filter was unable to remove the odor of the wastewater. Our filter was also unable to remove chemicals because of the fact that it was a mechanical filter and not a chemical filter. We were also unable to change the pH level. I also think that any pathogens in our waste water would not have been removed.

 

Ways to improve:

Through the research and observations I have made, I think we could make the following improvements to our filter. I think that the smell of the waste water was caused by ammonia. Although my group was unable to test for this, ammonia is commonly found in agricultural runoff. Ammonia cannot be removed by any of the materials we were provided with, however, ammonia can be removed by chlorination. If I were to create a new version of my filter, I would add chlorine tablets between the polyester floss and the sand. The chlorine tablets would remove the ammonia, and the resulting product would be filtered out by the activated carbon. I would also add more activated carbon in my filter as we were limited by the amount of supplies we had in class.