Week 3

Solar Concentrator Design

During this week, work on the Solar Concentrator Design was done. The following drawing was done to summarize our discussion:

A large TV screen, as shown by the picture above, will be used to magnify the sunlight into one spot, directing all the heat energy to that spot. This will make that spot very hot, and it will be able to heat up anything placed there quickly. This can be used to store a large amount of heat in a short amount of time. Using the tilt of the TV screen and rotation of the support below that (which is drawn more in detail to the right side), this concentrator can face all directions and can be turned as needed. This leads into an issue that needs to be solved: making the concentrator tilt automatically so that it is always facing the Sun.


Biosand Filter Research


As for the biosand filter research group, research was done exploring the flow rate of biosand filters and their effectiveness in filtering water.  With regards to the flow rate:

In order to determine the effectiveness of the biosand filter we had to understand the flow rate of the water through the porous sand.  Disinfection is directly correlated with the time the water takes to travel through the biosand filter. The longer the water spends in the sand the more effective the disinfection process will be. How long the water spends in the sand depends on the pressure of the water and the components of biosand filter.  In order to calculate how water flows through sand we can use Darcy’s Law which is Q = K(Ah/L).  In this equation the Q is the flow of water, K is the hydraulic conductivity, A is the cross-sectional area, h is the head loss, and L is the distance the water travels.  With this equation we will be able to calculate the flow rates of various amounts of water in the biosand filter. The goal is to find a flow rate that encourages the maximum amount of filtration through the biosand filter.

Research for the effectiveness of the biosand filter showed:

*The biosand filter has been proven to remove:

• Up to 100% of worms
• Up to 100% of protozoa
• Up to 98.5% of bacteria
• 70 to 99% of viruses
• Up to 95% of turbidity
• Up to 95% of iron

Our group used this as the basis to prove the merit of the solar disinfection step being added into the overall process.  Solar disinfection has been proven to remove the following:

Bacteria	Disease	SODIS Reduction
Escherichia Coli	Indicator for Water Quality and Enteritis	99.99%
Vibrio Cholera	Cholera	99.99%
Salmonella Species	Typhus	99.99%
Shigella Flexneri	Dysentery	99.99%
Campylobacter Jejuni	Dystentery	99.99%
Yersinia Enterocolitica	Diarrhoea	99.99%

*The SODIS method was for 6 hours at 40 degrees Celsius.

In addition, the SODIS method removes the following types of viruses

Virus	Disease	SODIS Reduction
Rotavirus	Diarrhoea, Dysentery	90%
Polio Virus	Polio	99.9-99.99%

This research serves as the basis for proving the value of the additional solar disinfection step.  Results from studies show that the solar disinfection method is a valuable step in continuing to remove harmful pathogens and viruses from water to make sure that it is a clean and as safe as possible to drink.