Update README.md

README.md

@@ -2,88 +2,90 @@
 
 We have made a [spreadsheet model](https://docs.google.com/spreadsheets/d/1ZwIqP0B2wM6QrpZTNiK1hNnNmIEIal7qxYdgEJz8Iog/edit?usp=sharing) of "flash" decompression.
 
-One of our volunteers, Hardhik, has begun prototype a flash system. We need someone to design a reaction vessel.
+One of our volunteers, Hardhik, has begun to prototype a flash system. We need someone to design a reaction vessel.
 
 # Biochar Toilet
 
-A reliable toilet that could quickly reduce human fecal matter to completely sanitary biochar would make the pooreset people of the
-Earth healthier. In many communities, Western-style sewage systems would be very expensive, and impractical for other reasons,
-such as geology, the lack of density in farming communities made of small land holdings, a lack of capital, and a lack of
-social and political organization able to dig the trenches and lay pipes efficiently.
+A reliable toilet that could quickly reduce human fecal matter to completely sanitary biochar would make the poorest people of the
+Earth healthier. In many communities, Western-style sewage systems would be very expensive and impractical due to
+geology, the lack of density in farming communities made of small land holdings, a lack of capital, and a lack of
+social and political organization to dig trenches and lay pipes efficiently.
 
 Reducing a typical human stool to biochar requires an energy input of about 600 kilojoules (see detailed analysis in referenced spreadsheet).
 Even for the poorest people, the cost of this electricity is quite low---less than one US cent \$0.01USD. One kilowatt hour is 3.6 MJ (megajoules).
 Expensive electrical power around the world is $0.45/kWh is $0.075 USD--or less than eight cents. Even if our toilet is inefficient, it
-seems possible to make toilet whose operating cost is affordable for the poorest persons, at $27.375 per year (this cost does not include
-the capital costs of the toilet.)
+seems possible to make a toilet whose operating cost is affordable for the poorest people, at $27.375 per year (this cost does not include
+the capital costs of the toilet).
 
-Biochar can be used a fuel or a garden amendment. Note, however, that human stools are so small (128 grams nominally) that this is not an meaninful approach for carbon sequestration.
+Biochar can be used as a fuel or a garden amendment. Note, however, that human stools are so small (128 grams nominally) that this is not a meaninful approach for carbon sequestration.
 
 
 # Initial Design Idea
 The problem of toilets is a widely researched area. Our approach may be slightly novel. We start from some assumptions:
+
 1. Electicity is an input.
 1. Complete biological safety of the endproduct is required.
 1. We choose to temporarily ignore the capital costs of the toilet in our research.
 1. Because we have to char in the absence of oxygen to prevent combustion, we can assume that we need an air-tight or pressure controlled
     reaction vessel.
 1. A major problem in charring is to first dry the sample, and drying is primarily a problem of water transport.
 
-We therefore conclude our basic design will be a sealed reaction vessel with a valve that allow steam to be transported out
+We therefore conclude that our basic design will be a sealed reaction vessel with a valve that allows steam to be transported out
 of the reaction chamber. We will heat the chamber contents until a desired pressure is created and then transport the water
 vapor away by opening the valve. The valve will be controlled so as to avoid most gases (air) from enterring the chamber.
 Opening the valve will "flash" the water in the sample into steam, which will have the desirable properties of being
 extremely murderous to any organisms present in the sample, and physically destructive to both plant and animal cells.
-Possibly it will even physically disrupt the sample, which may be advantageous.
+It may even physically disrupt the sample, which could be advantageous.
 
 When the sample is sufficiently dry, we will heat it to charring temperature. When the sample is fully charred, and then cooled
 and possibly wetted to avoid spontaneous combustion, the
 operator will be alerted that the sample is safe to remove and either combust or use as a garden amendment.
 
 # Energy Analysis
 
-Volunter Nupur Bhalla working with Invention Coach Robert L. Read has produced a [Google Sheet](https://docs.google.com/spreadsheets/d/1ZwIqP0B2wM6QrpZTNiK1hNnNmIEIal7qxYdgEJz8Iog/edit?usp=sharing) represnting an energy analysis of the drying and heating process.
+Volunter Nupur Bhalla working with Invention Coach Robert L. Read has produced a [Google Sheet](https://docs.google.com/spreadsheets/d/1ZwIqP0B2wM6QrpZTNiK1hNnNmIEIal7qxYdgEJz8Iog/edit?usp=sharing) representing an energy analysis of the drying and heating process.
 
 
 
 # Heating Mechanisms
-Since we will have a sealed metal reaction vessel, radio frequency (RF) heating is possibility.
+Since we will have a sealed metal reaction vessel, radio frequency (RF) heating is a possibility.
 However, it is expected to become less effective as the sample dries.
 We therefore intend to explore the possibility of using simple Joule resistive heating of a stainless steel vessel directly.
 RF heating, however, has the advantage of heating the sample volumetric (not require conduction), which may be a tremendouse advantage.
 
 # Phase 1
 
-Having gotten a new volunteer who wants to build an embedded system, we propose a Phase 1 as a "spike" prototype to test out the basic principles.
+Having gained a new volunteer who wants to build an embedded system, we propose a Phase 1 as a "spike" prototype to test out the basic principles.
 In this phase, the goal is to build the smallest, safest system that we can. 
 We imagine making a "reaction vessel" which is very small---perhaps 50 ml, large enough to dry a piece of fruit as a test.
 
 As Nupur Bhalla and I have demonstrated in the energy analysis spreadsheet, the act of producing char can be divided into two operations:
 drying to low water content, and then raising the temperature sufficiently to produce char (all in the absence of additionaly O2 to avoid
-combustion.) The Phase 1 system needs to raise the temperature enough to produce a pressure in the chamber of 2 atmospheres (or possibly 
+combustion). The Phase 1 system needs to raise the temperature enough to produce a pressure in the chamber of 2 atmospheres (or possibly 
 a lower pressure for testing), but if the sample has a high water content, this will likely occur at just a little above the boiling point 
-of water (100C, or a little higher under pressure.) The Phase 1 system does not need to operate above 150C, which will make it slightly safer.
+of water (100C, or a little higher under pressure). The Phase 1 system does not need to operate above 150C, which will make it slightly safer.
 
 When the solenoid valve is opened, the pressure drop will instantly lower the boiling point of water, causing the water to "flash" into
 steam. This has the advantage that it "destroy" the sample. For example, a grape with an intact skin would literally be expected to "explode". 
 This will likely be messy in the chamber. However, this is NOT bad for treating a human stool---it has the advantage of being very 
 destructive of intact cells, including bacterian and plant cells that are in the stool, for example.
 
-However, opening the solenoid valve briefly is likely to spray hot, scalding steam out the valve. It is essential for saftey that this steam enter
-a separate containment chamber. The purpose of the containment chamber is allow the offgases to cool (probably liquefying). The containment 
-chamber should be close to atmospheric pressure, probably open to the atmospher. An odor-reduing carbon filter may connect the containment 
+However, opening the solenoid valve briefly is likely to spray hot, scalding steam out the valve. It is essential for safety that this steam enter
+a separate containment chamber. The purpose of the containment chamber is to allow the offgases to cool (probably liquefying). The containment 
+chamber should be close to atmospheric pressure, probably open to the atmosphere. An odor-reducing carbon filter may connect the containment 
 chamber to the outside air, but that is not necessary for Phase 1---but the safety concerns are.
 
-For that reason, an emergency pop-off valve needs to be build into the Phase 1 reaction vessel. A software error or someother error could 
-easily allow the recation vessel to develop high pressure which would be dangerous.  However, a lot of the software and machinery 
+For that reason, an emergency pop-off valve needs to be built into the Phase 1 reaction vessel. A software error or some other error could 
+easily allow the reaction vessel to develop high pressure, which would be dangerous.  However, a lot of the software and machinery 
 design could be accomplished with a reaction vessel which is simply not tightly closed. Although this will not allow the "flashing" of
 the steam, in other ways the Phase 1 machine could be tested.
 
-If the reaction vessel is not sealed, then it could be constructed in many differnt ways---for example, with a babyfood jar of a Mason jar,
+If the reaction vessel is not sealed, then it could be constructed in many different ways---for example, with a babyfood jar, a Mason jar,
 or even a cardboard box. Since nylon melts at about 230C, it would even be possible to 3D print a nylon reaction vessel for Phase 1. (Nylon
 would not survive the 400C temperatures needed for charring.)
 
 I imagine a BOM for the Phase 1 system to be:
+
 1. An I2C pressure sensor with a range of at least 2.5 Atms.
 2. A heating element, such as a power resistor. (Two of these in series might work: [https://www.digikey.com/en/products/detail/te-connectivity-passive-product/HSC1001R0J/2055297?_gl=1*15lsl1x*_up*MQ..&gclid=Cj0KCQjwzYLABhD4ARIsALySuCTm8nkVdOfNr_GjOg-3iFiSH7pkuDwZ5D46byvvL9cms07OnCRo0-UaAs2xEALw_wcB&gclsrc=aw.ds](https://www.digikey.com/en/products/detail/te-connectivity-passive-product/HSC1001R0J/2055297?_gl=1*15lsl1x*_up*MQ..&gclid=Cj0KCQjwzYLABhD4ARIsALySuCTm8nkVdOfNr_GjOg-3iFiSH7pkuDwZ5D46byvvL9cms07OnCRo0-UaAs2xEALw_wcB&gclsrc=aw.ds).)
 3. A digital thermometer (This operates up to 125C, which may be good enough for phase 1: [https://www.adafruit.com/product/642](https://www.adafruit.com/product/642)).
@@ -97,7 +99,7 @@ I imagine a BOM for the Phase 1 system to be:
 
 # Research Plans
 
-We indent to continue theoretical research and design. Simultaneously, we intend to make a mini-scale (Phase 1) system, to test our assumptions
+We intend to continue theoretical research and design. Simultaneously, we intend to make a mini-scale (Phase 1) system, to test our assumptions
 and calculations. That is, we intend to make a very small reaction vessel which can be temperature and pressure controlled, surmounted
 with a controllable valve. We will test this system's ability to dry and char small samples of biological material, such as bread.
 
@@ -109,4 +111,13 @@ with a controllable valve. We will test this system's ability to dry and char sm
 for Efficient Thermal Pretreatment of Wastewater Sludge",
 Md. S. Ferdous, Ehssan H. Koupaie, Cigdem Eskicioglu, and Thomas Johnson*
 
+# Volunteer Opportunities
+
+This project is currently active! That means that there is still time to get involved, meet the team, and work towards providing a sanitary option for impoverished communities. Please reach out to us if you have a background in any of the following areas:
+
+* Mechanical engineering
+* Heat engineering
+* Chemistry
+
+If interested in joining the Biochar Toilet or projects like it, reach out to Inventor Coach [Robert L. Read](read.robert@gmail.com) or Volunteer Coordinator [Miriam Castillo](https://www.linkedin.com/in/cstllgtrrz/). Ultimately, our mission is to further the reach of open-source medical engineering, and invent in the public, for the public. Check out our [Volunteer Page](https://www.pubinv.org/volunteer/) to learn more.