Question 19N.3.SL.TZ0.11b
| Date | November 2019 | Marks available | [Maximum mark: 1] | Reference code | 19N.3.SL.TZ0.11b |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | State | Question number | b | Adapted from | N/A |
Ensuring the delivery of water to homes requires a pressure to be maintained in the pipes. Biofilm formation will reduce the pressure in the pipes. Three experimental water piping systems were set up and the water was treated before entering the system in one of the following three ways:
• untreated water (Control)
• ultrafiltration (UF) filters particles <500 nm
• nanofiltration (NF) filters particles <1 nm.
The drop in pressure of the water coming out of the tap at the end of the system compared to the pressure of water entering the system was measured.
[Source: reprinted from Water Research, 47(8), G. Liu, M.C. Lut, J.Q.J.C. Verberk, J.C. Van Dijk, A comparison of additional
treatment processes to limit particle accumulation and microbial growth during drinking water distribution, pp 2719–2728,
Copyright (2013), with permission from Elsevier ]
State one other way in which the formation of biofilms can be inhibited.
[1]
using bacteriophages/viruses
OR
adding biocides/bactericides/chlorine
OR
using cell dispersal agents ✔
