Dual reticulation and IPR schemes typically incorporate
highly effective advanced treatment technologies including
membrane filtration and disinfection processes (Wintgens
et al., 2005). However, treatment failures and cross-connections
between recycled water and potable water systems can
occur. For example, a random audit of properties connected to
a dual reticulation scheme in Sydney, Australia, identified 50
cross-connections prior to the deliverance of water to the
system and at least four post-commissioning incidents have
been reported since 2001 (de Rooy and Engelbrecht, 2003).
Such incidents can seriously compromise both public health
and customer confidence (Marks et al., 2003; Marks, 2007).
In water recycling schemes, there is a need for careful and
on-going management to ensure reliability of water treatment
performance to maintain full protection of public health.
Cross-connections between potable water systems and recycled
water pipes need to be rapidly identified. In order to
ensure such reliability and to be able to take action quickly if
treatment fails or if cross-connections are identified, some
form of real-time water quality monitoring is urgently
required. Current methods of online water treatment
Nomenclature
BOD biological oxygen demand
COD chemical oxygen demand
DO dissolved oxygen
DOM dissolved organic matter
EEM excitation–emission matrix
EPA Environmental Protection Agency
EPS extracellular polymeric substances
EWS early warning systems
GRAMS generalised rank annihilation models
IFE inner filtering effect
IPR indirect potable reuse
MCR multivariate curve resolution
MBR membrane bioreactor
MF microfiltration
NF nanofiltration
NTU nephelometric turbidity units
PARAFAC parallel factor analysis
PE polyethylene
PLS partial least squares
PVC polyvinyl chloride
RO reverse osmosis
SAT soil-aquifer treatment
SMP soluble microbial products
SS suspended solids
THM trihalomethane
TN total nitrogen
TOC total organic carbon
TP total phosphorous
UF ultrafiltration
WWTP wastewater treatment plant
864 water research 43 (2009) 863–881
monitoring systems are generally limited to a few simple
parameters including conductivity, total organic carbon (TOC)
and, in the instance of membrane processes, trans-membrane
pressure. The development of monitoring systems suitable for
the rapid assessment of process performance and water
quality is a key area requiring further research