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the BBUV in Kenya
Over the past six months, we had the opportunity to put our ideas for a large volume clean water solution to the test. Our successes from the “System Testing in Guatemala” spurred the interest of World Vision-Kenya (WV-K) via Business Connect – a global distributor of clean water solutions. WV-K has a pilot program underway, and they saw our system concept as a possible solution to help them achieve their goals. The assembly team included – from the WV-K: Collince Wasaga, Peter Ngodhe, Kennedy Obuya Odero – welder, Samwel Ouma Okello- plumber, Pauline Akinyi, Lorna Anyango, Wycliffe Omolo, Emily Rotich – from Business Connect: Daniel and Ashley Miesel – from Better Things: Mike Watkins, Mark Davis.
The Situation:
Initiated in 2015, WV-K is taking water from the Awach River in the Dol Kodera Forest in Homa Bay County, Kenya, with the focused goal of providing water for 100,000+ people in this region . The water harvested via river pressure and moved with gravity in an 8″ pipe, is sent to their purification complex approximately 800-900 meters from the inlet to the filter station.
The system components at this location include a chemical injection station, a flocculation track, settling tanks, a wash tank, and a clean water tank. This treatment facility utilizes the chemical Alum to weight undissolved solids in the water causing the particulates to settle at the bottom in the water tanks and the cleaner water to rise to the surface. After the Centrifuge (a process of settling tanks) and then chlorination, this water then distributes to the network, which, when finished, will stretch across 27 kilometers (photo – elements of the treatment plant), making the water available via water kiosks (photo – Kiosk). The current treatment method uses an average of 80kg of Alum per day (60 to 100kg) at the cost of $59USD per day or $21,535 per year.
They hope to use our most extensive version of the BlackBox Series filtration system, the BBUV, to eliminate their current chemical injection treatment process for not only this project but for future projects as well. (photos – Filter House construction, inlets, outlets, etc. – slider)
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The Application:
The challenge for us was to increase the filtration capacity of a single BBUV unit and meet the desired volume of 83m3 per hour or 1,992m3 per day.
Amplifying the design of our BlackBox High Volume (BBHV) unit to a 1″ architecture, we tripled the throughput from the BBUV´s base of 32 LPM (10 GPM) to as much as 113 LPM (30 GPM). The BBUV unit’s key feature, beyond its filtration capacity, is the reconfigurability to function in parallel as a group of filters – effectively increasing its volume capacity to filter water. In our testing, we had seen on the high end as much as 113 LPM (30 GPM) at 20 PSI; and on the low end, 90 LPM (24 GPM) at 40 PSI move through a single filter of our design.
Two banks – 6 unit BBUV systems were introduced into their purification system to achieve WV-K’s desire for 83m3 per or 1,992m3 per per day requires 1,383 LPM. (photo – BBUV). Each bank has the potential capacity to process 678 LPM * 2 units meet a possible flow rate of 1,356 LPM. This variance was within the margin of success, at the time of committing to the project.
Late Discoveries:
After the project commitments, we became aware of a few critical details.
- The water pressure in the 8″ tube from the river was only 8 meters of head pressure (nominally 13 PSI). The lower pressure meant the BBUVs would have less pressure to work with when compared to the testing in our shop. The good news for us was that this assured pressure regulation is not needed for protecting the filter’s fibers.
- The final location of the bacterial filters was directly off the river and not after any of their current methods to reduce the turbidity of the river.
- WV-K built a building to accommodate the 2 – banks of BBUVs units. Using two – 4″ supply lines, from the 8″ pipe are fed into each of the respective banks of BBUV units, bypassing the existing facilities. These supply lines run from points before the chemical injection and then connect after the settling tanks.
Filter Placement:
WV-K built a building to accommodate the 2 – banks of BBUVs units. Using two – 4″ supply lines, from the 8″ pipe are fed into each of the respective banks of BBUV units, bypassing the existing facilities. These supply lines run from points before the chemical injection and then connect after the settling tanks.
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The Results:
In the development of the BBUV filters, this was the first system of its size placed in active operation. The results were varied, both less than favorable and favorable.
Less than favorable results:
- Based on our conceptual designs and testing, we went with a plan using 4″ PVC tubing for the filter housings to maximize the flow rate of the filters themselves. This design proved to be not as easy to service in field use as it was in our shop. A BIG “Thank You” goes to team member Daniel Miesel and his “better tools for the job (6″ pipe wrenches),” which he generously made available for installation. Without which we would not have achieved functionality of the system.
- The PVC Schedule 40 material available in the western hemisphere, is not the same as what is available outside of this hemisphere. This detail forced us to make creative solutions in minor repairs needed as a result of the import process. As well, transitioning from one PVC format to another became another obstacle to work around. In the future, it will be best to utilize flange fittings to unify the two PVC formats.
- The head pressure of 8 meters (nominally 13 PSI) was not adequate to push the amount of water needed through the two lines and meet the desired volume of 83m3 per hour.
- The turbidity of the river is too high for only the microfilters to clean up. Their strength is removing particulates down to .1 microns. The filters perform optimally when the incoming turbidity is 50 NTU or less.
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Favorable results:
- The system works.
- Connecting multiple units via manifolds works well to increase volume capacity.
- In terms of effectiveness, we performed before and after filter testing on two separate occasions, three months apart. The first, presented by the Homabay County Municipality works, showed a reading of 528 NTU straight from the river before the filtration and 1.6 NTU after the filtration. The second test, performed by a laboratory in the city Kisumu 3 months later and more comprehensive to include bacterial removal, showed a turbidity count of 187 NTU and the total Coliform count at 87 and E. Coli at 49 particulates per 100 mL before filtration. The WHO max tolerance for potable water is 5 NTU and Bacterial counts of <2 per 100mL. The BBUV removed contaminates to NIL on both counts. (photos and video of before and after; testing results in PDF)
Summary / Next Steps:
- The capacity of the BBUV is proven to remove turbidity and bacteria on a community scale. Even with the high levels of turbidity causing mud to overwhelm the filters, and the lower head pressure of nominally 13 PSI, the system did achieve nominal equivalency of 400m3 per day.
- The high turbidity could be mitigated to some extent with more frequent backflushing. But while additional backflushing can address part of the increases in turbidity, there is a balance between the practical amount of cleaning cycles and expending more water than is gained. External pressurized backflushing tanks may help clean the filters, in the event of an excessively turbulent environment. However, the efficient use of the technology would be to place an in-line method for reducing the turbidity to less than 50 NTU, before the BBUV units.
- To increase the river pressure to meet demand, additional banks of units to offset the lower PSI coming from the river should increase the volume to reach the desired amount of 80m3 per hour.
- The current PVC design proved to be problematic in maintenance. We (Better Things) plan to improve the BBUV system’s filter housings for more straightforward installation and easier servicing. This upgrade will include an enclosure for each unit and quicker access to the filter units. These steps will take us closer to reaching some of our other goals, such as modular assembly kits for global accessibility, easier mounting of the BBUV units, and a more definitive branding to the look of our product.
theBlackBox Series water filtration systems produce clean water. They are practical for a variety of applications that include cleaning wells or municipal water systems, purifying natural water sources such as lakes and rivers, and use in industries such as agriculture, fish farming, and potable water supply. We will continue to test our units on-site in Guatemala, Kenya, and other locations.
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