Membrane and Desalination Technologies - TCE Moodle Website

184 N.K. Shammas and L.K. Wang
Table 4.12
General overview of continuous indirect integrity monitoring (Source: US EPA)
Description Monitoring some aspect of filtrate water quality that is indicative of the removal
of particulate matter
Purpose Monitor a membrane filtration system for significant integrity problems between
direct integrity test applications
Applicability Membrane units in a site-specific membrane filtration system
Frequency Continuous
7. DESIGN EXAMPLE: CHALLENGE TEST SOLUTION DESIGN SCENARIO
Design a challenge test solution using the following assumptions and parameters:
1. The target LRV for the challenge test is 4 log.
2. The membrane module has an area of 100 m 2 .
3. The maximum flux for the module 85 Lmh, where Lmh = L/(m 2
4. The module operates in deposition mode.
5. A test duration of 30 min is required to conduct the required sampling.
6. A system hold-up volume of 200 L.
7. The filtrate sample volume used during the challenge test is 500 mm.
8. The detection limit for the filtrate sampling technique is 1 particle per 500 mL.
9. Challenge particulate seeding is conducted via continuous in-line injection.
Solution:
Step 1: Determine the required test solution volume.
Vtest ¼ QpTmin
R þ Vhold þ Veq SF; (3Þ
where Tmin = 30 min (from given information), R = 100% (standard for deposition mode
hydraulic configuration), Vhold = 200 L (from given information), Veq = ? (to be determined),
SF = ? (to be determined), Qp = ? (to be determined).
Assume that the equilibrium volume is equal to three times the holdup volume,
Veq ¼ 3Vhold;
Veq ¼ 3ð200LÞ; Veq ¼ 600L:
A suitable safety factor is approximately in the range of 1.1–1.5. Since no other information
is given in this example, a value for the safety factor is arbitrarily assumed.
SF ¼ 1:2
The filtrate flow, Qp, can be calculated simply by multiplying the given maximum flux and
the membrane area (and converting to convenient units), as shown below:
h).