At each of the full-scale UV project sites, the effectiveness of the UV system will be evaluated through bioassay dose estimations (MS-2 bacteriophage challenges). This will occur at each location on a quarterly basis. It is expected that UNH-ERG will conduct the MS-2 bacteriophage challenge events every quarter at SWBD; at IWC, the initial MS-2 bacteriophage challenge event will be conducted by UNH-ERG. It is anticipated that IWC will conduct the later MS-2 bacteriophage challenges with UNG-ERG providing all needed MS-2 bacteriophage and performing all analyses. The MS-2 bacteriophage procedure to be used is outlined below.
In the lab prior to beginning the challenge:
1. Wash all plastic containers first in a mixture of hot water and Liqui-Nox® detergent (Alconox Inc.; New York, NY) then rinse with laboratory grade water. Dry all containers at 60°C.
2. Titer stock MS-2 virus solution, to ensure that an adequate amount of virus is present, typically a minimum of 1011 PFU/mL is required.
3. Prepare necessary quantity of MS-2 virus solution by placing 50 mL of stock (~1011 PFU/mL) into 4L of laboratory grade water in plastic containers for a final concentrations of about 109 PFU/mL.
In the treatment plant:
1. Switch pump station to 'off-line' for 8 hours. The UV system will be plumbed in a configuration that isolates it from the rest of the plant.
2. Set flow to 290 gallons per minute (gpm) and check to see that all system pressures are as close as possible to typical system pressures.
3. Clean UV reactors, quartz sleeves, and sensors with 20% Muriatic Acid (HCl) or other solution as required.
4. Let UV reactors warm up for 10 minutes.
5. Record UV sensor readings.
6. Install in-line mixer or driver flow to mixer.
7. Install injection pump and set pump to draw for the 4L container with MS-2 virus.
8. Start injection pump and set to maximum pumping rate (100% stroke and 100 cycles per minute = 300 mL/minute).
9. Let system stabilize for 5 minutes.
10. Purge a minimum of three volumes between initial and final sampling point.
11. Open initial and final sampling point valves and purge them for 10 seconds.
12. Adjust valve flow to a small steady stream and place 1 L plastic composite bottle below water stream.
13. Capture composite sample from stream for 10 minutes.
14. Cap composite bottle and turn upside down a couple of times to mix composite.
15. Pour composite into 50 mL sterile plastic centrifuge tube (Fisher Scientific Co., Springfield, NJ), cap tightly, and chill at 4°C in cooler for analysis within 24 hours.
16. Wash composite bottles/caps at least three times with raw plant influent water containing no MS-2.
17. Maintain stock reservoir by adding stock from other 4L containers.
18. Repeat #8-16 until finished sampling.
19. Remove in-line mixer or bypass mixer.
20. MS-2 coliphage will be enumerated as described in Section 3.3.3.