WAL S.A. Summary of the evaluation of the Wal SafeWater UTC dome ceramic filter used in conjunction with the Wal SafeWater UTC gravity filtration system. Tested for cryptosporidium oocyst removal conducted by an independent laboratory
In this test we evaluated the flow rate and capacity of an OEM dome ceramic to reduce Cryptosporidium oocysts (crypto). The USEPA purifier guide standard (USEPA PGS) requires a 3-log reduction of crypto for point of use (POU) drinking water purification devices.
Three dome ceramics (HS part# 006-00400) were evaluated for flow rate and crypto reduction to the USEPA PGS. The average flow rate at 0% capacity and maximum head height of 295mm measured 87mL/min when used in conjunction with the Wal SafeWater UTC disinfecting cartridge and measured an average of 162mL/min when used alone. Intact the dome ceramics were able to reduce crypto by ≥3log reduction meeting the USEPA PGS.
One of the three ceramics was found to have a compromised seal which resulted in increased flow rate (195mL/min) and decreased crypto efficacy (<2.41 log reduction). Procedure
a- Assemble three mock devices using orange Home Depot buckets (off set hole to avoid lip on bottom). b- 20L orange bucket mark 295mm line c- OEM dome ceramics numbered DDC 1 – 3 (HS part# 006-00400) d- UTC lot# TPBR-3662 e- Flush with 15L of dechlorinated tap water (GTW1), discard filtered water and allow device to sit overnight 1- Measure flow rate a- Fill to 295mm with GTW1 b- Measure flow rate over 4-minutes c- Refill to 295mm, measure flow rate over 4-hours or until entire top volume is filtered whichever comes first 2- Cryptosporidium cyst challenge a- Remove UTC from the dome ceramic b- Prepare 15L of GTW1 at 25˚C c- Add crypto to the 15L of water for a minimum concentration of 1x10 3 oocyst/mL (Cryptosporidium parvum oocysts, Waterborne Inc)
d- Fill device to 295mm line (~15L) e- Sample collection i.
Allow the first liter to filter and discard
ii.
Collect the second liter
iii.
Process entire second liter for crypto reduction quantification1
f- Log reduction calculation (LRV) LRV = (log10 influent oocyst/mL concentration) â&#x20AC;&#x201C; (log10 effluent oocyst/mL concentration) Results
Table 1: Flow rate measured using GTW1 water at 25Ë&#x161;C and 295mm initial head height with UTC cartridge attached. mL/min Sample
4 min flow
1 hr flow
DDC-1
83
68
DDC-2*
195
125
DDC-3
98
83
DDC-2**
80
51
* ceramic #2 had a compromised seal between the ceramic and the ceramic housing ** ceramic #2 after two part epoxy was used to fix the seal between the ceramic and the ceramic housing
Table 2: Cryptosporidium cyst reduction data (UTC cartridge removed) Flow
challenge
Sample
sample
mL/min
cyst/mL
cyst/mL
LRV
DDC-1
150
1.28E+03
0.00E+00
3.11
DDC-2*
283
1.28E+03
> 5.10E+00
< 2.41
DDC-3
172
1.28E+03
0.00E+00
3.11
* ceramic #2 had a compromised seal between the ceramic and the ceramic housing
Conclusion
The tested dome ceramic can provide a 3-log reduction of Cryptosporidium oocyst (intact ceramic only). With a head pressure of 295mm the ceramic will provide a maximum flow rate of <100mL/min when used in conjunction with the WalSafe UTC cartridge and a maximum flow rate of <175mL/min when used without the UTC cartridge