1. Comparison of water reuse treatment options to maximize
resource recovery from wastewater
Pranoti Kikale1, Pranjali Kumar1†, Sherri Cook1
INTRODUCTION TREATMENT OPTIONS
METHODS
Water reuse along with resource recovery is an important
means to address water scarcity problems. This study’s
goal is to identify and optimize treatment scenarios to
enable energy neutral water reuse. Life cycle assessment
and systems modeling methodologies are being used to
compare the treatment scenarios. Figure 1 shows each
treatment train being consider for the treatment of
domestic wastewater to non-potable reuse standards.
ACKNOWLEDGEMENT
We thank University of Colorado, Boulder’s Department of Civil,
Environmental and Architectural for funding the first author.
GAC Filter DesignLife Cycle Assessment Data Collection
Wastewater Treatment
LCA is an standardized methodology to
evaluate the environmental consequences
of a product or activity. Life cycle
inventory data has been collected from
Agrifootprint databases and the US EPA’s
TRACI method is being used for the life
cycle impact assessment method.
Table 1: Energy requirements for aerobic wastewater
treatment; data is based on experimental literature.
Energy requirements and production for mainstream
anaerobic treatment (membrane bioreactor); data is
based on values from the experimental literature.1
Fig. 5. Coagulant dose required
to achieve a 30% DOC
reduction for a wastewater
effluent from a fully aerobic
and from a fully anaerobic
wastewater treatment system.
Fig. 6. Relative
environmental impacts
for two common
coagulants, alum and
ferric chloride (FeCl3).
Fig. 7. GAC mas required
for the filtration of both
aerobic and anaerobic
effluents over 40 years.
Reactivated GAC accounts
for 90% of the total mass.
Fig. 8. Environmental
impact of the production of
fresh (virgin) and
reactivated GAC,
normalized to fresh GAC.4
• The Edwards model was used to determine the
coagulant doses (Fig. 5).
• For both anaerobic and aerobic effluents, alum requires
the highest dose for DOC removal and has the largest
negative environmental impacts, compared to FeCl3.
Fig. 3. Process flow diagram for granular activated
carbon (GAC) filtration system. This system includes
pretreatment of wastewater effluent using coagulation
to remove dissolved organic carbon (DOC). 2
Fig. 4. Design steps
for GAC filtration. 3 Table 2. GAC filter design data.
RESULTS
Fig. 9. Environmental impacts for both
treatment trains: 1) aerobic wastewater
treatment followed by GAC filtration;
and 2) fully anaerobic wastewater
treatment followed by GAC filtration.
• There is a tradeoff between different types of
environmental impacts for both treatment trains
(either fully aerobic or fully anaerobic wastewater
treatment). So the train with the lowest
environmental impact is not clear.
These results include the following unit processes:
wastewater treatment energy consumption and
production, coagulant production and transportation,
fresh GAC production, GAC reactivation energy
requirements, GAC transportation and disinfection.
Energy production for anaerobic wastewater
treatment assumed 100% recovery of dissolved
methane.
Fig. 10. Unit process contribution for the
global warming potential (GWP) impact
category for both treatment trains.
• Energy required for the
production and reactivation of
GAC had the greatest relative
contribution to GWP (51% for
aerobic and 59% for anaerobic).
• For GWP, energy requirements
for wastewater treatment had
the second largest relative
contribution (45% for aerobic and
36% for anaerobic).
• The production of coagulant and
transportation of GAC and
coagulant contributed to about
5% of the total GWP impact for
each treatment train.
Fig. 1. Treatment trains
with conventional
aerobic and mainstream
anaerobic processes. The
functional unit of this
modelling study is the
production of nonpotable
reuse (NPR) water from
medium strength
wastewater that is
generated at 20 million
gallons per day, over a 40
year time frame.
1Department of Civil, Environmental and Architectural; †Trussell Technologies Inc.
Fig. 2. Overview of life cycle assessment (LCA)
methodology and phases used in this study.
CITATIONS1Leo et al (2007)’Anaerobic membrane bioreactors: Applications and research directions, Env Sci and
Tech 36:6, 489-530; 2 EPA, U. S. E. P. (2012). 2Guidelines for Water Reuse, (September). 3Metcalf & Eddy,
2007. Water Reuse; 4US EPA, 1973. Process Design Manual for carbon Adsorption;