WASTEWATER

16.1.3 Industrial water reuse
Industrial water reuse (see Chapter 6) involves
recycling industrial wastewater for industrial uses
(process water) and non-industrial uses (irrigation,
landscape irrigation, non-potable urban uses,
etc.). Industries can also use treated municipal
wastewater. Recycled industrial water has been
used as process water in power stations, textile
manufacturing, paper industry, oil refineries,
heating and cooling, and steelworks for a long
time. New applications of industrial water reuse
are also emerging, such as the use of treated
wastewater as cooling water in big data centres
(for example, the Google data centres in Belgium
and Georgia, USA). More efficient water recycling
and process technologies can ultimately lead to
the closing of the water loop in industries (see Box
14.2), while reducing water use by more than 90%
(Rosenwinkel et al., 2013).
16.1.4 The ‘fit-for-purpose’ concept
‘Fit-for-purpose’ water reuse means that the
required treatment level is defined by water quality
requirements of the intended use. Most nonpotable
reuse options require a quality lower than
that of drinking water, so that secondary treatment
is often adequate (see Section 5.5). However,
barriers to wider applications of this approach
remain, including the lack of appropriate and
flexible regulatory and institutional frameworks.
Potential health and environmental risks can also
be reduced through appropriate safety control
measures, such as the multiple-barrier approach
(WHO, 2006a) (see Section 16.4).
The ‘fit-for-purpose’ water reuse concept has been
successfully applied in the West Basin Municipal
Water District in El Segundo, California, USA (see
Box 12.2), which treats water to five distinct levels
of quality suited for different specific uses (Walters
et al., 2013).
16.1.5 Wastewater use for
environmental benefits – Replenishing
water resources
Common uses of wastewater for environmental
benefits include the replenishment of water
resources through groundwater recharge, river
flow restoration, water augmentation in lakes and
ponds, and restoration of wetlands and biodiversity
(see Chapter 8).
Aquifer recharge. Artificial aquifer recharge
through the intentional injection of treated
wastewater for subsequent recovery or to
enhance ecosystems is a common practice.
The main limitations are related to the aquifers’
BOX 16.4 PHOSPHORUS (P) RECOVERY
GAINING MOMENTUM
The most common form of phosphorus recovery
from wastewater takes place as struvite
precipitation. The most attractive financial options
are those where the recovery takes place early and
allows the operator to save on the costly removal
of unwanted struvite within the treatment system.
However, in view of the sale of the recovered P,
there are no financially attractive options yet that
can compete directly with phosphate-ore-based
fertilizers in the market (Schoumans et al., 2015).
Short-term price volatility, long-term price hikes, and
increasing concern for P insecurity on the political
agenda (relating to concerns of food insecurity and
environmental degradation) may provide additional
incentives for recycled P over unsustainable mining.
Marketing strategies for recovered phosphorus
The Ostara Company in Canada, specialized in
private–public partnerships with wastewater
treatment plants, has successfully applied P-recovery
as crystalline struvite pellets branded ‘Crystal Green’,
which can be used as a commercial fertilizer, by
transforming the unwanted struvite formation in the
pipes. Revenue from the fertilizer sale is shared with
the city to offset the costs of the facilities.
The Austrian-based company ASH DEC Umwelt
AG developed a technology for sludge incineration
that completely destroys pathogens and organic
pollutants, followed by a chemical and thermal
treatment to produce an ash-based multi-nutrient
fertilizer, sold under the PhosKraft® brand.
Considering reduced disposal costs, the production
price is comparable to commercial fertilizers. The
payback period for investments in a full-scale plant
was estimated at 3–4 years (Drechsel et al., 2015a).
Contributed by Pay Drechsel (IWMI); Angela Renata Cordeiro
Ortigara (WWAP); and Dirk-Jan Kok and Saket Pande (TU Delft).
storage capacity and recharge rate. Aquifer recharge
offers several benefits, including water supply
augmentation and storage, maintenance of wetlands,
and saline intrusion prevention.
The Torreele Facility in Belgium produces highquality
infiltration water for indirect potable use via
groundwater recharge in the dune aquifers of St.
André, while offering environmental benefits such
as saline water intrusion prevention, sustainable
groundwater management and the enhancement of
natural values (Van Houtte and Verbauwhede, 2013).
Unintentional aquifer recharge with untreated or
insufficiently treated wastewater still occurs in many
areas. This needs special attention, as it can lead to
human and environmental health risks.
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