Last visit to site this year...

Wednesday/Thursday 5th/6th December

After a couple of days back in the WaterAid offices in Dhaka, it was time to return to site for one more time before I leave Bangladesh.

We had a brief meeting with the Mayor of Faridpur, a lovely chap, who is popular and has been in the post for several years.  His support for this project has been appreciated by all those involved, and hopefully we will maintain this good relationship.

Meeting the Mayor of Faridpur (cream shirt to my right) - please excuse the unsettling gentleman pictured on the desk calendar!

We downloaded another load of data, and the results are looking pretty consistent:

Test results for the 10 days of the trial

The plastic roofs are raising the temperature by about 10 degrees, with the metal and thatch a few degrees cooler than ambient.  

The filter beds are outperforming the flat beds significantly, after 10 days, the sludge in the flat beds was still very watery and increasingly odourous.  The sludge in the filter beds is now a very thick semi-solid and clumping together.  It could easily be removed and mixed with woody organics such as rice-straw.

 

Sludge in the thatched filter bed

Comparison between three samples from the flat beds (left) and filter beds (right)

So, we now know that a clear/ translucent plastic roof on a filter bed is the optimum roofing material and base design.  We're now planning the next round of tests.  We want to explore controlling air tightness and ventilation, and of course the obvious missing comparison - with no roof at all (remembering that the reason we have roofs are to enable performance during the rainy season, it may be that the remainder of the year, they could be open).

I'll update more once I'm back in the UK, but for now, I've got a plane to catch...