POZNAŃ UNIVERSITY OF LIFE SCIENCES
FACULTY OF ENVIRONMENTAL ENGINEERING AND SPATIAL MANAGEMENT
MSc Eng. Thanh Hung Nguyen
TREATMENT AND REUSE OF GREYWATER FOR
RYE-GRASS IRRIGATION
(OCZYSZCZANIE I PONOWNE WYKORZYSTANIE ŚCIEKÓW
SZARYCH DO NAWADNIANIA ŻYCICY TRWAŁEJ)
Doctoral dissertation
Supervisor:
prof. dr hab. inż. Ryszard Błażejewski
Co-supervisor:
dr hab. Marcin Spychała
Poznań 2019
TREATMENT AND REUSE OF GREYWATER FOR
RYE-GRASS IRRIGATION
(OCZYSZCZANIE I PONOWNE WYKORZYSTANIE ŚCIEKÓW
SZARYCH DO NAWADNIANIA ŻYCICY TRWAŁEJ)
Doctoral dissertation
THANH HUNG NGUYEN
Supervisor:
prof. dr hab. inż. Ryszard Błażejewski
Faculty of Environmental Engineering and Spatial Management.
Co-supervisor:
dr hab. Marcin Spychała
Faculty of Environmental Engineering and Spatial Management.
Dissertation Committee appointed by the Scientific Council of the Discipline:
Environmental Engineering, Mining and Energy
to be defended in public
on Thursday 28 November 2019
at 11:00 a.m. in Rada Wydzial room, Faculty of Environmental Engineering
and Spatial Management.
Chairman:
prof. dr hab. inż. Jolanta Komisarek
Faculty of Environmental Engineering and Spatial Management.
Reviewer:
prof. dr hab. inż. Janusz Łomotowski
Wrocław University of Environmental and Life Sciences.
dr hab. inż. Joanna Jeż-Walkowiak
Institute of Environmental Engineering
Poznan University of Technology.
Acknowledgements
I would like to extend my sincere thanks to my supervisor, Prof. dr hab. inż.
Ryszard Błażejewski, for his valuable support and supervision. His advice,
guidance, encouragement, and inspiration have been invaluable over the years.
Professor always keeps an open mind in every academic discussion. I admire his
critical eye for important research topics. This dissertation would not have been
completed without his guidance and support.
Additionally, I would like to thank dr hab. Marcin Spychała, for supporting
supervisor and his cooperative work. He gave me valuable help whenever I asked
for assistance. I have learnt many useful things from him.
Further, I would like also to take this opportunity to thank the governments
of Poland and Vietnam through Agreement between the Government of the
Republic of Poland and the Government of Vietnam giving the opportunity to study
in Poland and grant scholarships for my entire course.
The warmest thank to my colleagues at Department of Hydraulic and
Sanitary Engineering, Poznań University of Life Sciences, for the stimulating
discussions, supporting my works, and for providing the friendly environment in
which we have learnt and grown during the past 4+ years. Special thanks to Mrs
Jolanta Zawadzka for her help in laboratory measurements.
Last but not least, I would like to thank my family and friends, for their
constant love, encouragement, and limitless support throughout my life.
CONTENTS
LIST OF FIGURES .............................................................................................. iv
LIST OF TABLES ...............................................................................................viii
Abbreviation.......................................................................................................... x
ABSTRACT .......................................................................................................... 1
1.
INTRODUCTION........................................................................................ 4
1.1. Background ................................................................................................. 4
1.2. Definitions of terms ..................................................................................... 5
1.3. Sustainable water resources management principles ................................. 6
1.4. Current and threatening water shortages .................................................... 7
1.5. Importance of water reclamation and reuse ................................................ 7
1.6. Justification for the study ............................................................................. 8
2.
LITERATURE REVIEW ............................................................................ 10
2.1. Composition of greywater ......................................................................... 10
2.1.1. Quantity of greywater .......................................................................... 10
2.1.2. Quality of greywater ............................................................................ 12
2.1.3. Characterisation of greywater usability ............................................... 13
2.2. Greywater treatment ................................................................................. 15
2.3. Greywater reuse for irrigation .................................................................... 16
2.3.1. Standards and guidelines ................................................................... 16
2.3.2. Potential of greywater reuse for irrigation ........................................... 19
2.3.3. Storage and diversion of greywater for reuse ..................................... 21
2.3.4. Impacts of greywater reuse for irrigation ............................................. 23
2.3.4.1. Human health .............................................................................. 23
2.3.4.2. Soil .............................................................................................. 23
2.3.4.3. Groundwater ............................................................................... 25
2.3.4.4. Yields .......................................................................................... 26
2.4. Economics of greywater reuse .................................................................. 27
2.5. Perennial ryegrass and its characteristics ................................................. 29
2.6. Observed gaps in the literature ................................................................. 30
3.
PURPOSE, SCOPE AND RESEARCH METHODS ................................. 31
i
3.1. Purpose and scope of the research .......................................................... 31
3.2. Hypotheses ............................................................................................... 31
3.3. Research methods .................................................................................... 32
3.3.1. Material ............................................................................................... 35
3.3.2. Design of experimental with ryegrass ................................................. 38
3.3.3. Research process ............................................................................... 40
3.3.4. Experimental process on ryegrass...................................................... 40
3.3.5. Collecting data and analysis ............................................................... 44
4.
RESULTS OF THE STUDY ..................................................................... 46
4.1. Study on greywater reuse for ryegrass irrigation without fertilizer supply .. 46
4.1.1. Balance of substances in all treatment combinations ......................... 46
4.1.2. Main and interaction effects among factors influencing the dry mass
yield of ryegrass without fertilizer supply ...................................................... 49
4.1.2.1. Total dry mass of ryegrass after 3 harvests without fertilizer
supply....................................................................................................... 49
4.1.2.2. Total dry mass of ryegrass after 6 harvest without fertilizer supply
................................................................................................................. 57
4.1.3. Regression model for dry mass yield of ryegrass ............................... 64
4.1.4. Effect of irrigation water factors on soil pH.......................................... 65
4.1.5. Effect of irrigation water factors on soil EC ......................................... 70
4.1.6. Potential contaminant removal from greywater by planted ryegrass ... 75
4.2. Study on greywater reuse for ryegrass with fertilizer supply ..................... 79
4.2.1. Main and interaction effects among factors of irrigation water on dry
mass yield of ryegrass with fertilizer supply .................................................. 79
4.2.1.1. Total dry mass of ryegrass after 3 harvests with fertilizer supply 79
4.2.1.2. Total dry mass of ryegrass after 6 harvests with fertilizer supply 82
4.2.2. Effect of irrigation water factors on soil pH.......................................... 87
4.2.3. Effect of irrigation water factors on soil EC ......................................... 90
5.
DISCUSSION ........................................................................................... 95
5.1. Effect factors on total dry mass yield of ryegrass ...................................... 95
5.2. The leachate quality .................................................................................. 97
ii
5.3. Effect factors on the change in soil pH and EC ......................................... 98
5.4. Selecting factor settings for yield efficiency and reducing risk for planted
soil irrigated with tap and greywater ............................................................... 100
6.
CONCLUSIONS AND FUTURE RESEARCH ........................................ 112
6.1. Conclusions ............................................................................................ 112
6.2. Future research ....................................................................................... 113
References ....................................................................................................... 114
iii
LIST OF FIGURES
Figure 1.1. Overview of greywater terms ................................................................ 5
Figure 2.1. Choosing methods for greywater treatment to reuse .......................... 16
Figure 3.1. Photo of experimental ryegrass in laboratory ...................................... 33
Figure 3.2. The process of conducting the research ............................................. 34
Figure 3.3. Compositions of raw and treated greywater used for irrigation ........... 35
Figure 3.4. The lab-scale stand for greywater treatment ....................................... 36
Figure 3.5. Particle size distribution of planted soil (sand) .................................... 37
Figure 3.6 The pot for experiment ......................................................................... 37
Figure 3.7. Scheme of investigation with three factors (A, B, C) ........................... 38
Figure 3.8. The whole process of the study .......................................................... 40
Figure 3.9. Flowchart describing the entire experimental process on ryegrass ..... 41
Figure 3.10. Schedule of experiment: (a) without fertilizer supply (Stage II); (b) with
fertilizer supply (Stage III) ..................................................................................... 43
Figure 3.11. Flowchart for analysis from experimental design of the study ........... 45
Figure 4.1. Balance of COD mass on all treatment combinations from irrigation
water (Total mass matter = Uptake + Outlet) ........................................................ 46
Figure 4.2. Balance of total nitrogen mass on all treatment combinations from
irrigation water....................................................................................................... 47
Figure 4.3. Balance of total phosphorus mass on all treatment combinations from
irrigation water....................................................................................................... 48
Figure 4.4. Total dry mass yields of ryegrass after 3 harvests of all treatment
combinations without fertilizer supply. ................................................................... 50
Figure 4.5. Effect of the main factors on the total dry mass yield of ryegrass after 3
harvests without fertilizer supply ........................................................................... 52
Figure 4.6. Two-way interaction of two factors affecting the total dry mass yield of
ryegrass after 3 harvests (83 days) without fertilizer supply .................................. 53
iv
Figure 4.7. The two-way interaction effects of the factors in the low and the high
level of another factor after 3 harvests without fertilizer supply ............................. 54
Figure 4.8. Response surface as a function: (a) of tap water and treated greywater
(at raw greywater 5 mm/week); (b) of tap water and treated greywater (at raw
greywater 15 mm/week); (c) of tap water and raw greywater (at treated greywater
5 mm/week); (d) of tap water and raw greywater (at treated greywater 15
mm/week); (e) of treated greywater and raw greywater (at tap water 5 mm/week);
(f) of treated greywater and raw greywater (at tap water 15 mm/week) ............... 56
Figure 4.9. Total dry mass yield of ryegrass after 6 harvests for all treatment
combinations without fertilizer supply .................................................................... 57
Figure 4.10. Effect of the main factors on the total dry mass yield of ryegrass after
6 harvests (179 days) without fertilizer supply....................................................... 60
Figure 4.11. Two-way interaction of two factors on the effects of the total dry mass
yield of ryegrass after 6 harvests (179 days) without fertilizer supply ................... 60
Figure 4.12. The two-way interaction effects of the factors in the low and the high
level of another factor after 6 harvests without fertilizer supply ............................. 61
Figure 4.13. Response surface of total dry mass yield of ryegrass as a function: (a)
of tap water and treated greywater (at raw greywater 5 mm/week); (b) of tap water
and treated greywater (at raw greywater 15 mm/week); (c) of tap water and raw
greywater (at treated greywater 5 mm/week); (d) of tap water and raw greywater
(at treated greywater 15 mm/week); (e) of treated greywater and raw greywater
(at tap water 5 mm/week); (f) of treated greywater and raw greywater (at tap water
15 mm/week)......................................................................................................... 63
Figure 4.14. Correlation between irrigation water and total dry mass yield of
ryegrass ................................................................................................................ 64
Figure 4.15. pH of soil before initial and after experiment for all treatment
combinations without fertilizer supply .................................................................... 66
Figure 4.16. Effect of main factors on soil pH without fertilizer supply .................. 68
Figure 4.17. The two-way interaction of two factors on effect of the change in soil
pH after finishing experiment (179 days) without fertilizers‘ supply ....................... 69
v
Figure 4.18. Two-way interaction for all combinations of levels for the two factors
on effect of the change in the soil pH after finishing experiment without fertilizer
supply.................................................................................................................... 70
Figure 4.19. Soil EC of all treatment combinations before initial and after
conducted experiment. .......................................................................................... 71
Figure 4.20. Effect of main factors on the change in soil EC ................................. 73
Figure 4.21. The two-way interaction of two factors influencing soil EC after
finishing experiment (179 days) without fertilizer supply ....................................... 73
Figure 4.22. Two-way interaction for all combinations of levels for the two factors
on change in the soil EC after finishing experiment .............................................. 74
Figure 4.23. The average pH of irrigation water and leachate of all treatment
combinations during experiment ........................................................................... 75
Figure 4.24. The average EC of irrigation water and leachate of all treatment
combinations during experiment ........................................................................... 76
Figure 4.25. COD of leachate from all treatment combinations for mean COD
influent of raw greywater and treated greywater were 320 and 120 mg .dm-3,
respectively ........................................................................................................... 77
Figure 4.26. Total nitrogen concentration of leachate from all treatment
combinations ......................................................................................................... 78
Figure 4.27. Total phosphorus concentrations of leachate from all treatment
combinations ......................................................................................................... 78
Figure 4.28. Total dry mass yield of ryegrass after 3 harvests of all treatment
combinations with fertilizer supply ......................................................................... 80
Figure 4.29. Main factors affect on the total dry mass yield of ryegrass after three
harvest times with fertilizer supply......................................................................... 81
Figure 4.30. The two-way interaction of two factors on the total dry mass yield of
ryegrass after three harvest times with fertilizer supply ......................................... 82
Figure 4.31. Total dry mass yield of ryegrass after six harvests for all treatment
combinations ......................................................................................................... 83
vi
Figure 4.32. Main factors affect on the total dry mass yield of ryegrass after six
harvests with fertilizer supply ................................................................................ 85
Figure 4.33. The two-way interaction of two factors on the total dry mass yield of
ryegrass after six harvests with fertilizer supply .................................................... 86
Figure 4.34. Two-way interaction for all combinations of levels for the two factors
on the total dry mass yield of ryegrass with fertilizer supply .................................. 86
Figure 4.35. Soil pH for all treatment combinations after experiment with fertilizer
supply.................................................................................................................... 87
Figure 4.36. Two-way interaction of two factors on the change in soil pH after six
harvests with fertilizer supply ................................................................................ 89
Figure 4.37. Two-way interaction for all combinations of levels for two factors soil
pH with fertilizer supply ......................................................................................... 89
Figure 4.38. Soil EC for all treatment combinations before and after finishing
experiment with fertilizer supply ............................................................................ 90
Figure 4.39. Main effects of factors influencing soil EC......................................... 92
Figure 4.40. Two-way interaction of two factors influencing soil EC after six
harvests with fertilizer supply ................................................................................ 93
Figure 4.41. Two-way interaction impact for all combinations of levels for two
factors on change in the soil EC with fertilizer supply ........................................... 94
vii
LIST OF TABLES
Table 2.1. Water consumption and generated greywater in countries in the world
.............................................................................................................................. 11
Table 2.2. Greywater quality in chosen countries.................................................. 12
Table 2.3. Quality of greywater from household devices and appliances .............. 13
Table 2.4. Some regulations/guidelines of water reuse for irrigation ..................... 18
Table 2.5. Costs for greywater treatment systems ................................................ 29
Table 3.1. Model matrix for full factorial experimental design................................ 38
Table 3.2. The matrix of experimental design (Full factorial experimental design) 40
Table 3.3. Volumes of irrigation water for each irrigation time interval (3 days) .... 42
Table 4.1. COD and nutrient uptake by pots during whole experiment ................. 49
Table 4.2. ANOVA table for effect of all factors on total dry mass yield of ryegrass
after three harvests without fertilizer supply .......................................................... 51
Table 4.3. ANOVA for fitting model with 6-effect to the total dry mass yield of
ryegrass after 3 harvests without fertilizer supply.................................................. 52
Table 4.4. ANOVA table for effect of all factors on total dry mass yield of ryegrass
after six harvests without fertilizer supply (intercept not shown) ........................... 58
Table 4.5. ANOVA for fitting model with 5-effect to the total dry mass yield of
ryegrass after six harvests without fertilizer supply ............................................... 59
Table 4.6. Final model parameters........................................................................ 65
Table 4.7. ANOVA table for all factors on effect of the change in soil pH (with
transformed exp(pH)) ............................................................................................ 67
Table 4.8. Results from fitting model of 3-effects on soil pH describing by
transformed soil pH after experiment (179 days) without fertilizer supply ............. 67
Table 4.9. ANOVA for effect of all factors on changing EC of planted soil ............ 71
Table 4.10. ANOVA for fitting model with 6-term effects describing the change in
soil EC after experiment without fertilizer supply ................................................... 72
viii
Table 4.11. ANOVA for effect of all factors on total dry mass yield of ryegrass after
3 harvests (after 83 days) with fertilizer supply (intercept not shown) ................... 80
Table 4.12. ANOVA for effect of all factors on total dry mass yield of ryegrass after
six harvests with fertilizer supply ........................................................................... 83
Table 4.13. ANOVA for fitting model with 2- effects to total dry mass yield of
ryegrass after 6 harvests with fertilizer supply....................................................... 84
Table 4.14. ANOVA for effect of all factors on soil pH with fertilizer supply .......... 88
Table 4.15. ANOVA for fitting model with 1-effect on soil pH after experiment with
supply fertilizer ...................................................................................................... 88
Table 4.16. ANOVA for effect of all factors on soil EC on transformed soil EC ..... 91
Table 4.17. ANOVA for fitting model with 4- effect on the change in soil EC
(transformed EC) after experiment with supply fertilizer ........................................ 92
Table 5.1 Matrix for selecting factor settings for yield efficiency for ryegrass and
reducing risk of planted soil (for only main factors) ............................................. 101
ix
Abbreviation
-
A: Tap water
-
ANOVA: Analysis of variance is a collection of statistical models
-
B: Treated greywater
-
C: Raw greywater
-
COD: the chemical oxygen demand
-
d.m: dry mass
-
EC: Electrical conductivity
-
FC: Fecal Coliform
-
GW: Greywater
-
MBR: Membrane bioreactor
-
RBC: Rotating biological contactor
-
RGW: Raw greywater
-
SBR: Sequencing Batch Reactor
-
T.C: Treatment combination
-
TGW: Treated greywater
-
TSS: Total suspended solids
-
WHO: World Health Organization
x
ABSTRACT
Greywater combined with tap water and raw greywater from laundry, bath
and washbasin was studied to evaluate effect of the irrigation water factors on the
total dry mass yield of ryegrass and soil. The greywater was treated in lab-scale
set-up constructed out of lamella settler and filters. The full factorial experiment
with two levels (low level 5 mm/week, and high level 15 mm/week) for three factors
of irrigation water was designed. After preliminary tests (stage I), the experiment
was carried out for two cases: without fertilizer supply (stage II) and with fertilizer
supply (stage III) lasting 186 days each. Ryegrass was harvested 6 times during
experiment, the total dry mass yields of 3 and 6 harvests were evaluated. Soil pH
and EC were measured before and after finish of each experimental stage.
The results of study show that all main factors (tap water, treated
greywater, raw greywater) influenced significantly the total yield of ryegrass after
three and six harvests in stage II. The most important factor influenced the total
yield was treated greywater. Moreover, all interactions between two factors had
significant effect on the total yield, except for interaction between treated
greywater and raw greywater after 6 harvests. The experiment of stage II showed
that tap water, treated greywater and their interaction had significant effect on soil
pH, similarly all factors of irrigation water and their interactions influenced on soil
EC. Treated greywater was the most important factor influencing on soil pH, while
tap water was decisive in the case of soil EC.
In the experimental stage III, there were no significant effects of any factors
and their interactions on the grass yield after 3 harvests. However, interaction
between tap water and raw greywater as well as between treated greywater and
raw greywater had significant effects on the total yield after six harvests. Soil pH
was significantly influenced by interaction between tap water and raw greywater
while soil EC by all main factors and interactions between tap water and treated
greywater as well as between tap water and raw greywater, in which tap water
was the most important factor.
In addition, the quality of leachate have tended to improve after 51 days of
ryegrass growth till the end of stage II, indicating high treatment efficiency of
greywater in the root zone.
Keywords: greywater, irrigation, tap water, greywater reuse, perennial ryegrass.
1
STRESZCZENIE
Badania miały na celu ocenę wpływu nawadniania mieszaniną wody
wodociągowej, ścieków szarych surowych (z pralni, wanny i umywalki) i ścieków
szarych oczyszczonych na plon suchej masy życicy trwałej oraz na glebę. Ścieki
szare były oczyszczane w układzie laboratoryjnym, zbudowanym z osadnika
lamelowego
i
filtrów.
Zaplanowano
i
zrealizowano
pełne
doświadczenie
wieloczynnikowe dla dwóch poziomów nawadniania (poziom niski: 5 mm/tydzień i
poziom wysoki: 15 mm/tydzień) dla trzech czynników. Po ukończeniu badań
wstępnych (etap I) przeprowadzono doświadczenie dla dwóch wariantów: bez
nawożenia (etap II) i z nawożeniem (etap III), trwającymi 186 dni każdy. Życicę
ścinano sześciokrotnie w trakcie doświadczenia, oceniano plony suchej masy
całkowitej dla trzech i sześciu zbiorów. Pomiar pH i przewodności elektrycznej
gleby wykonywano przed i po zakończeniu każdego etapu doświadczenia.
Wyniki badań wykazały, że wszystkie główne czynniki (woda wodociągowa,
ścieki szare surowe i ścieki szare oczyszczone) istotnie wpływały na całkowity
plon życicy po trzech i sześciu zbiorach w II etapie badań. Najistotniejszym
czynnikiem wpływającym na plon życicy były oczyszczone ścieki szare. Ponadto
wszystkie oddziaływania między dwoma czynnikami miały istotny wpływ na plon, z
wyjątkiem oddziaływania między ściekami szarymi oczyszczonymi a ściekami
szarymi surowymi po sześciu zbiorach. Doświadczenie II etapu wykazało, że woda
wodociągowa, ścieki szare oczyszczone i ich wzajemne oddziaływanie miały
istotny wpływ na pH gleby; podobnie wszystkie czynniki i ich wzajemne
oddziaływanie miały wpływ na przewodność elektryczną gleby. Ścieki szare
oczyszczone były najistotniejszym czynnikiem wpływającym na pH gleby,
natomiast woda wodociągowa miała decydujące znaczenie dla przewodności
elektrycznej gleby.
W
III
etapie
doświadczenia
nie
stwierdzono
istotnego
wpływu
poszczególnych czynników i ich wzajemnych oddziaływań na plon życicy po trzech
zbiorach. Jednak oddziaływania między wodą wodociągową i ściekami szarymi
surowymi oraz między ściekami szarymi oczyszczonymi i ściekami szarymi
surowymi miały istotny wpływ na plon po sześciu zbiorach. Oddziaływanie między
wodą wodociągową a surowymi ściekami szarymi miało istotny wpływ na pH
gleby, natomiast wszystkie główne czynniki oraz ich interakcje, a także interakcje
2
między wodą wodociągową i ściekami szarymi surowymi miały wpływ na
przewodność elektryczną gleby, a najistotniejszym czynnikiem okazała się woda
wodociągowa. Ponadto jakość odcieku uległa poprawie po 51 dniach wzrostu
życicy i utrzymywała się do końca etapów II, co wskazuje na dużą skuteczność
doczyszczania ścieków szarych w strefie korzeniowej.
Słowa kluczowe: ścieki szare, nawadnianie, woda wodociągowa, wykorzystanie
ścieków, życica trwała.
3
1. INTRODUCTION
1.1. Background
Water is essential for all life, and freshwater is one of the most important
resources in all human activities. However, it is becoming shortage because of
urbanization, population growth, climate change, etc. Recently, water shortage is
happening not only in some countries but also expending over worldwide.
According to the World Water Assessment Programme (WWAP), about three
billion people in parts of Asia and Africa will be faced with water shortages in 2025
(WWAP, 2012). Mekonenn and Hoestra (2016) reported that two-thirds of the
global population (4.0 billion people, mainly in India and China) live under
conditions of severe water scarcity at least one month of the year, and half a billion
people face severe water scarcity all year round (Mekonnen and Hoekstra, 2016).
In order to reduce water shortage stress, one of the ways that has potential
is wastewater treatment reuse for some human activities. Hence, greywater is
emerging and considering as an alternative resource if we have a reasonable
treatment for reuse. It looks a resource and has the potential to cope with water
scarcity because of low concentration of contaminants and pathogens, accounting
for a significant volume of wastewater discharge from household. Moreover,
greywater containing some nutrients has potential to stimulate for developing plant
(Ghaitidak & Yadav, 2013). In addition, treated greywater is applied for toilet
flushing that can save from 40 to 60 litres/p.day (Gross et al., 2015). However, the
reuse of treated greywater depends on many factors as living cost, technology,
available resources, water scarcity level, regulatory policies and environmental
concerns. Treated greywater reuse is a method to save water resource which is
closely linked due to the greywater accounts for two-thirds of the total domestic
wastewater from households. Moreover, it contributes to decrease in wastewater
flow into central wastewater treatment plant (Morel & Diener, 2006).
Greywater reuse for irrigation has to treat ensures reducing health risk, soil,
aesthetic, odour. Especially, greywater reuse will be beneficial and efficient when
applying a suitable treatment method for a specific purpose of reuse. However, at
present, this issue is still ambiguous and there have not been many studies
published.
4
1.2. Definitions of terms
Greywater is defined as wastewater from households which includes many
flows from baths, showers, tubs, washbasin and laundry machines without kitchen
(kitchen sinks, dishwashers), and toilets (AL- Jayyousi, 2003; Roesner et al.,
2006). However, some different definitions of greywater that include all sources
from a household, excepting that from toilets exist (Gross et al., 2015, Ludwig,
2007). In addition, Gross et al. (2015) distinguished two categories: light greywater
(generated from bath, shower and wash basin), and dark greywater (generated
from kitchen sink and washing machine). Overview of greywater terms is shown in
figure 1.
Wastewater from household
Black water
Greywater
Toilets
(with water closets)
Dark
greywater
Light
greywater
Bath and
shower
Wash
basin
Laundry
Kitchen
Figure 1.1. Overview of greywater terms
For the purpose of this study, greywater is defined as a household
wastewater from bath and shower, laundry machine, hand basin; excluding that
from kitchen.
Greywater reuse means using raw greywater or treated greywater for other
consumptions of human. In more detail, treated greywater is used to substitute tap
water for an active purpose which is not required for drinking water such as
irrigation, washing street, toilet flushing, etc. Greywater reuse has a potential to
remarkedly reduce using tap water and water costs in households.
Reclaimed water is a term synonymous with recycled water; it is
wastewater that is treated by many processes to meet specific water quality
criteria (Asano et al., 2007).
5
In addition, some terms were defined by Asano et al. (2007) such as nonpotable reuse, directly potable reuse, indirectly potable reuse. Non-potable reuse
that means all water applied for reuse from wastewater treatment processes does
not associate with directly and indirectly potable reuse. In here, directly potable
reuse that is advancing wastewater treatment supplies directly into the source of a
water treatment plant while water for indirect potable reuse is stored in lake,
reservoir, or groundwater before using.
1.3. Sustainable water resources management principles
Water demand is increasing because of population growth and human
activities while water resources are deteriorating in quality and water scarcity over
the world. Therefore, humankind needs a strategy for the sustainable
management of water resources. It plays a crucial role to ensure current water
demand and safeguard water resources for future generations.
One of the criteria for sustainable water resources management is a
sustainable water resources system. It was defined by American Society of Civil
Engineers as ―Sustainable water resources systems are those designed and
managed to fully contribute to the objectives of society, now and in the future,
while maintaining their ecological, environmental, and hydrological integrity.‖
(Asano et al., 2007). According to Asano (2017), to ensure the sustainability of
water resources management one needs to conduct water conservation, water
reclamation and reuse and many different managements as preserve ecosystems,
encourage water reclamation and reuse, or design for resilience and adaptability
(Asano et al., 2007).
Doubtless, water reclamation and reuse are important ways to contribute to
sustainable water resources management. The AWWA research foundation report
(1999) showed that total water uses in a single-family home with water
conservation was lower by 32% than without water conservation. Besides,
greywater reuse is also an essential factor for sustainable water resources
management because it is not only improving the state of water shortage but also
water conservation sources.
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1.4. Current and threatening water shortages
Water shortage is not a new issue in dry continents that often face it as
Australia, Southwest America, Africa, Middle East. However, it is becoming more
frequent and long-lasting not only in arid or semi-arid regions but also expanding
to cover the world in the context of global climate change and the steady
population growth. Many countries in the Middle East and North Africa are facing
severe water scarcity which is also spreading to Asia and South Africa (Lazarova
and Akica, 2005). This problem is increasing because water availability is limited
by agricultural activities, urbanization together with climate change, threatening
ecosystems over the globe. Indeed, the areas where two-thirds of the world‘s
population lives are always facing water shortages for at least one month in the
year (WWAP, 2017). Moreover, one half of the population living in India and China
facing water shortages (WWAP, 2017). In the Global Risks Report of the World
Economic Forum (2015), water supply crisis was identified as the highest top for
risk level for our current times and future (Forum, 2015). With the current threat
level, the World Wide Fund for Nature (WWF) predicts that two-thirds world‘s
population
will
be
faced
water
shortages
in
2025
(https://www.worldwildlife.org/threats/water-scarcity).
1.5. Importance of water reclamation and reuse
Water reclamation and reuse is one of the crucial ways for sustainable
water resources management. On-site treated wastewater reuse reduces burden
for conveyance system to centralized waste water treatment plants. Water supply
of high quality can be supplemented by alternative reclaimed water. According to
Gross et al (2015), potable water was saved from 10-30% of the urban water
demand if greywater in the household has been reused.
Water reuse plays an important role to reduce water shortage stress and is
a sustainable water resource management method. To cope with water scarcity,
many countries as Australia, the United States (US), and many countries in the
Middle East have applied greywater reuse. Moreover, they are interested in
developing policies and encouraging the development of technology to greywater
reuse effectively and safely (Pinto et al., 2010, Reichman et al., 2013). Guidelines
for reuse of greywater have been issued in the United Kingdom (UK), Australia,
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