January 22, 2010 - Ddegeya

We were planning to have our solar cooker prototypes out in the morning, but it started raining and did not clear up until afternoon. We did bring the cookers out in the afternoon, but the water went up only to about 60 C, and none of the WAPIs melted.

In the morning, Dave and Mike went to fix BH1---quite successfully. The BH does not give a lot of water, but is in working order. Turbidity measurements were done on the BH (20-30 NTU) and the nearby pond (about 500 NTU). One thing that worries us is that Joseph and Eddie (the two people meant to be testing the Biosand filters) usually get their water from the 500-NTU pond. This means that an additional cloth pre-filtration step must be done. We explained the situation to Joseph and he said that he would be able to use the BH, or pay someone (e.g. 500 shillings) to get water from Nalongo. We have not discussed the situation with Eddie.

In the meanwhile, Kevin washed 4 batches of sand, when the water traffic at BH4 was low after the rain. He also started feeding P1 water into the working Biosand filter prototype (this prototype had so far been fed with BH4 water, which has very little colonies on the Petrifilm tests). After about 60L of P1 water to the filter, we performed Petrifilm tests on the influx and the efflux in the evening. This will hopefully give us some estimate of the filter efficiency.

What worries us a little is the flow rate. When the filter is filled to the top, the flow rate is roughly 1 L per minute (same as yesterday and the day before). However, if we just add a little water (e.g. 1 L), this amount could take maybe 4 minutes to clear. For the second prototype (which we are building), we propose reducing the thickness of the fine sand from 20 cm to 15 cm in hope of increasing the flow rate (so far we only have about 12 cm of washed fine sand anyways).

In the afternoon, Kevin walked to Kinoni to get 6 bolts for the BHs, two wash basins that MIT-EWB owe Engeye (we drilled holes into those for diffuser plates). He was looking for some cardboard sheet, but was unable to find them (he was told to look for them in Masaka). He ended up spending 1000 shillings on a used cardboard box whose dimension, when stretched out, was perfect for the inner lining of the EasyLid box cooker, which Kevin is going to attempt.

In the meanwhile, Mike and Dave went to BH5, and had some more trouble. The pipe seemed stuck in an awkward position and wouldn't go down---they needed a carjack to lift this. John lent them a carjack and they went back to BH5 with no avail---now they needed two carjacks. We do hope that BH5 could be returned to its original shape, or otherwise it would leave MIT-EWB in a rather embarrassing light.

Freddie came to say goodbye---he is going to Kampala for vacation and will not see us before we leave.

Towards the evening, Mike and Dave started drilling holes and connecting the pipes for the second sand filter. Unfortunately, the collector pipe was not threaded long enough for a rubber o-ring, and we ended up just applying a lot of silicon glue and hoping for the best tomorrow. In the meanwhile, Kevin washed 2 batches of sand and then worked on building the EasyLid box cooker. Everything went according to plan until the step of fitting the inner box. The problem is that the inner box is much shallower than the outer box, and it was necessary to give the inner box some support from underneath such that a heavy thing (e.g. a kettle full of water) does not cause its collapse. We first tried folding a long thin strip of cardboard sheet many many times to the right height. This proved rather unstable. Then we tried cutting some plastic bottles to the right height. This worked better. But Joseph proposed cutting some pieces of wood. This was promptly done with Joseph's excellent carpentership, but we were unable to find anything to stick these pieces of wood together to the right height---nails were too short for the thick wood blocks, and we were unable to find duct tape. We are sure that we can work something out eventually, but at this time it was getting a little too dark, so we just called it a day.