First Big Obstacle for Project Implementation

While it may not seem like a big problem to some, a fast flow rate through a biosand filter reduces the efficacy of contaminant removal and its overall benefits for its users.

The Guatemalan workers and the U of I project team were perplexed why the first biosand filter that we implemented had a flowrate of 45 second per 1 liter rather than 60 seconds as is recommended. A partner of ours, Forrest Kendall of Servants 4 Him, suggested that it could result from a multitude of reasons. Not enough sand in the filter to slow the water flow, too coarse of sand, or poor source materials. The U of I project team worked with the Guatemalan workers to figure out the cause and the best solution.

Finally, after putting our heads together, we discovered that we could arc the internal tube in the biosand fitler, thereby providing more space to add sand to the filter. We will also wash the sand media less. Washing the sand removes organics from the source sand but also removes some of the finer material. We were most likely overwashing the sand causing the finer sand to be removed and thereby increasing the water flow through the sand.

We will be testing our solution this Sunday with a newly constructed filter. Both the local expertise and our engineering knowledge contributed to the solution. But without working together, we would never overcome this problem.