Introduction
In this project we learned about water and created a project focused around our water system. This unit was focused around the chemistry behind water related things, like water treatment and purification. My group decided to make our project about designing a way to turn wastewater into drinking water in Novato. This is very relavant due to the droughts that we frequently face in California. Using wastewater as a source of drinking water would be a good way to reduce the amount of water that we waste and make it a more abundant resource. We used a water treatment plant design that used multiple filtration techniques and bacteria to get rid of waste. This treatment style is being used in places around the world, and has been proven to be an effective technique to treat wastewater. This facility would also be self sustaining, as the bacteria would be able to generate electricity in the process of digesting the waste.
Content
Solution: a homogeneous mixture of two or more substances uniformly dispersed throughout a single phase
solute: in a solution, the substance that dissolves in the solvent
solvent: in a solution, the substance in which the solute dissolves
ionic vs. molecular: Molecular compounds are formed with covalent bonds. Two nonmetals are joined together by sharing electrons. Ionic compounds are formed with ionic bonds. A metal and a nonmetal transfer electrons.
polarity: polarity is caused by differences in electronegativity in atoms. One side of the molecule has a positive charge and the other side is negative. This causes electrons to be more attracted to one side than the other.
Solubility: the ability of one substance to dissolve in another at a given temperature and pressure
dissolving ions in solution: ions are attracted to the water molecules due to the slightly charged parts of the water molecules
organic mater in water bacteria & virus: In unfiltered water there is bacteria and other harmful substances that can be deadly if consumed. That is why proper water purification is vital. The amount of organic matter like dirt or algae in water is known as TDS, or total dissolved substances
pH & what it measures: pH measures how acidic or basic the water is. It stands for probability of hydrogen.
pH scale: each number on the scale indicates a different pH, 7 is neutral, lower numbers are more acidic, and higher numbers are more basic. Where it is on the scale is represented by the color that the water turns when you do the pH test
drink-ability range: In order to be safe for human consumption water has to be within certain parameters. The pH level should be 7 or close to 7. The maximum TDS is 500 mg/L. There also has to be no traces of lead in the water, and the levels of chlorine and other chemicals have to be very small.
Our Methods of Filtration
Sludge and bar screens- These screens do preliminary filtration to remove any large solid particles, like hair, plastics, and fibres
Sedimentation- This removes suspended particles from the water. The velocity of the water is slowed down so the particles fall out of suspension. Particles will naturally fall to the bottom of the tank due to gravity
Bacteria- Bacteria is added to the water to remove all the solid wastes. The two types of bacteria that are used are Geobacter and Shewanella Oneidensis. The water is oxygenated so the bacteria can survive. The bacteria liberates electrons during respiration, generating electricity. Microbial fuel cells. Electrons transferred to electrode. Electron flux moves to anode or cathode
Crossflow Microfiltration- High pressure water is pushed through a pipe with membrane. Particles remain trapped on one side of the membrane, but water can get through it
Reverse Osmosis- High pressure water is pushed through a tank containing a Reverse Osmosis Membrane. Particles are filtered out using the semipermeable membrane, then drained out to keep the filter clear
UV Light Disinfection- A UV light is used to kill any bacteria that are left after reverse osmosis and microfiltration. A type of UV light called far-UVC is used that kills microbes but is not harmful to humans
Chlorine Dioxide- Oxidizes naturally occurring organic and inorganic compounds and organisms. Helps to destroy bacteria, viruses, and some parasites
Coagulation- Flocculation- Particles combine into larger floc with addition of compounds (Iron, Aluminum). Rapid spinning forms clumps. Sedimentation sets the sludge at the bottom
Granulated Activated Carbon Filter- Removes chemicals, mainly the chlorine. Improves taste and odor. Activated charcoal absorbs and traps toxins and chemicals.
Chemical Treatment- Small amounts of chlorine and sodium hydroxide are added to the water. This makes sure that no microbes are left
Reflection
One of the highs of this project was communication. Our group discussed things with each other and were always able to compromise. There was never any arguments when people wanted to move the project in a different direction than someone else. Also, our brainstorm at the beginning was very effective. We wrote down everyone's ideas then decided on a group which one we liked best. Everyone's ideas were given an equal chance of being picked. Another high was our collaboration. On each part of the project there were at least two people working together. We supported each other and worked together to get the project done. Every part of the project was done in collaboration, and none of it was entirely the work of an individual.
One of the lows was that we could've divided up the work better. Half of the group ended up doing most of the work, so we should've split it evenly between group members at the beginning. This was mostly due to what parts of the project people were most interested in working on, so in the future we could make an effort to expand on that part of the project and make it just as important as the other parts. Another low is that we could've been more creative with our project. We focused our project on something that has already been done, and in the future we could use more creativity to think of an entirely new solution to a problem, or at least put our own unique spin on the solution.
One of the lows was that we could've divided up the work better. Half of the group ended up doing most of the work, so we should've split it evenly between group members at the beginning. This was mostly due to what parts of the project people were most interested in working on, so in the future we could make an effort to expand on that part of the project and make it just as important as the other parts. Another low is that we could've been more creative with our project. We focused our project on something that has already been done, and in the future we could use more creativity to think of an entirely new solution to a problem, or at least put our own unique spin on the solution.