A Practical Approach to Water
Conservation for Commercial
and Industrial Facilities
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A Practical Approach to Water
Conservation for Commercial
and Industrial Facilities
Mohan Seneviratne
Queensland Water Commission, Australia
AMSTERDAM
•
BOSTON
•
HEIDELBERG
•
LONDON
NEW YORK
•
OXFORD
•
PARIS
•
SAN DIEGO
SAN FRANCISCO
•
SINGAPORE
•
SYDNEY
•
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Dedicated to my parents Barbara and Yase
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Contents
Foreword xvi
About the Author xviii
Acknowledgement
xix
1 Water Conservation – A Priority for Business 1
1.1 Introduction 1
1.2 Global Water Resources Availability 2
1.3 Human Need for Safe Drinking Water and Proper Sanitation 3
1.4 Meeting Agricultural Needs 6
1.5 The Impact of Climate Change 8
1.6 Business Sector Water Usage 11
1.7 Nine Reasons for Business to Reduce Their Water
Consumption
15
1.8 Conclusion 22
References 22
2 Basic Water Chemistry 25
2.1 Overview 25
2.2 Solubility Principles 26
2.3 Common Substances Found in Water 26
2.3.1 pH 26
2.3.2 Dissolved Gases 28
2.3.7.2 Bacteria 40
2.3.7.3 Protozoa 41
2.3.7.4 Algae 42
2.3.7.5 Helminths 42
2.3.7.6 Fungi 42
2.3.8 Heavy Metals 42
2.3.8.1 Chromium 42
2.3.8.2 Cadmium 43
2.3.8.3 Lead 43
2.3.8.4 Mercury 44
2.3.9 Radionuclides 44
References 44
3 Saving Water: Step by Step 46
3.1 Developing a Sustainable Water Management Plan 46
3.2 Step 1: Seek Senior Management Commitment 50
3.3 Step 2: Appoint A Water Conservation Manager 51
3.3.1 Responsibilities of the Water Conservation
Manager
51
3.4 Step 3: Gather Baseline Data and Review Usage 52
3.5 Step 4: Identify Improvement Opportunities 55
3.5.1 Carry Out an Assessment of Management
Systems
55
3.5.1.1 One-2-Five Water
®
– Management
Diagnostic System
55
3.5.2 Technical Assessment 56
Operational Principles
86
5.2.1.2 Recirculating Cooling Water Systems –
Basic Concepts
88
5.3 Types of Cooling Towers 92
5.3.1 Induced Draught Cross-flow Cooling Towers 93
5.3.2 Induced Draught Counter-flow Cooling Towers 93
5.3.3 Forced Draught Wet Cooling Towers 94
5.3.4 Evaporative Condensers 94
5.4 Water Conservation Opportunities 94
5.4.1 Reducing Involuntary Water Loss 95
5.4.1.1 Minimising Overflow of Water from
Cooling Tower Basins
95
5.4.1.2 Incorrect Piping Configuration 96
5.4.1.3 Leakage from Pipes, Joints and Pump
Glands
96
5.4.1.4 Drift Loss 96
5.4.1.5 Splash 96
5.4.2 Reducing Voluntary Water Loss 96
5.4.2.1 Increasing Cycles of Concentration 97
5.4.2.2 Install Flowmeters on Make-up and
Blowdown Lines and Conductivity Meters
in Blowdown Lines
98
5.4.2.3 Operate Blowdown in Continuous Mode 98
5.4.2.4 Install Sidestream Filtration 99
5.4.3 Improving Operating Practices 100
6.3.4 Geothermal Cooling Systems 129
References 130
7 Steam Systems 132
7.1 Introduction 132
7.2 Steam System Principles 133
7.2.1 Pre-treatment 134
7.2.2 Steam Generation 139
7.2.2.1 Firetube Boilers 139
7.2.2.2 Watertube Boilers 140
7.2.2.3 Waste Heat Recovery Boilers 143
7.2.3 Steam Distribution System 143
7.2.3.1 Thermostatic Traps 144
7.2.3.2 Mechanical Traps 144
7.2.3.3 Thermodynamic Traps 144
7.2.3.4 Fixed Orifice Condensate Discharge Traps
(FOCDT)
145
7.3 Steam and Energy Conservation Opportunities 146
7.3.1 Repair Steam Leaks 147
7.3.2 Maximise Condensate Recovery 148
7.3.2.1 Condensate Quality and System
Protection
150
7.3.2.2 Minimise Water Logging of Pipes 151
Contents xi
7.3.3 Minimising Boiler Water Blowdown 151
7.3.3.1 Blowdown Control 151
7.4 Calculating the “True” Cost of Steam 154
References 155
8 Industrial Water Reuse Technologies 157
8.8.1 Chemical Precipitation 193
8.8.2 Ion Exchange 196
8.9 Adsorption 197
8.10 Membranes for Removal of Dissolved Ions 198
8.10.1 Overview 198
8.10.2 Dead-End and Cross-Flow Filtration 201
8.10.2.1 Dead-end Filtration 201
8.10.2.2 Cross-flow Filtration 201
xii Contents
8.10.3 Membrane Types 202
8.10.3.1 Microfiltration 202
8.10.3.2 Ultrafiltration 205
8.10.3.3 Nanofiltration 205
8.10.3.4 Reverse Osmosis 206
8.10.4 Membrane Structure 206
8.10.5 Membrane Configurations 207
8.10.5.1 Spiral Wound 207
8.10.5.2 Hollow Fibre 207
8.10.5.3 Tubular 208
8.10.5.4 Plate and Frame 209
8.10.6 Membrane Performance Monitoring 213
8.10.6.1 Silt Density Index 214
8.10.6.2 Assessment of Scaling
Tendencies
215
8.10.6.3 Membrane flux 215
8.10.6.4 Permeate Recovery 216
8.10.7 Disposal of Brine Streams 217
8.10.8 Considerations When Selecting Membrane
Systems
10.3.2 Gathering Consumption and Billing Data and
Metering Water Consumption 241
10.3.3.1 Guest Rooms 241
10.3.3.2 Public Amenities 244
10.3.3.3 Kitchens 252
10.3.3.5 Laundry 259
10.3.3.6 Ice-Making Machines 259
10.3.3.7 Swimming Pools 262
10.3.3.8 Staff Rooms 262
10.3.3.9 Irrigation 262
10.3.3.4 Cooling Tower: Air-Conditioning and
Refrigeration 258
10.4 Staff Awareness Programmes 264
10.5 Guest Awareness Programmes 264
References 265
11 Commercial Buildings, Hospitals and Institutional Buildings 267
11.1 Introduction 267
11.2 Commercial Property – Office and Retail 267
11.2.1 Industry Structure and Water Usage 267
11.2.2 Water-Usage Benchmarks 269
11.2.2.1 Energy Consumption 270
11.2.2.2 Shopping Centres 271
11.2.3 Water-Saving Opportunities 272
11.3 Hospitals 275
11.3.1 Benchmarking Water Usage 276
11.3.2 Benchmarking Energy Consumption 277
11.3.3 Water Conservation Opportunities 278
11.3.3.1 Monitor Leakage 278
11.3.3.3 Steam Systems 279
11.3.3.4 Taps, Toilets and Urinals 279
307
13.5 Water Minimisation Measures in the Food-Processing
Industry
310
13.5.1 Avoiding Water Usage 310
13.5.2 Reducing Water Usage – Spray Nozzles 312
13.5.3 Reducing Water Usage – Washing 316
13.5.4 Reducing Water Usage – Clean-in-Place 316
13.5.5 Reducing Water Usage – Liquid Ring Vacuum
Pumps
320
13.5.6 Reducing Water Usage – Amenities Blocks 325
13.5.7 Reducing Water Usage – Evaporative
Condensers and Cooling Towers
325
13.5.8 Reducing Water Usage – Steam Systems 326
13.5.9 Reusing Water 326
13.5.10 Notes on Water-Reuse Applications 327
References 328
14 Oil Refining 330
14.1 Introduction 330
14.2 Oil Refining Processes 332
14.2.2 Thermal and Catalytic Cracking 332
14.2.3 Hydrotreating 333
14.2.4 Reforming 333
14.2.5 Alkylation and Polymerisation 333
14.2.6 Coking 333
14.2.7 Blending 333
14.2.1 Desalting, Crude Distillation and Vacuum
Distillation 332
Appendix
Worksheets
Conversions
Index
Chapter 1
Water Conservation – A Priority
for Business
Not a single drop of water received from rain should be allowed
to escape into the sea without being utilised for human benefit –
King Parakrama Bahu the Great of Sri Lanka (1153–1186)
1.1 Introduction
Water is life. We recognise the value of water and its role in our day-to-day
activities. Religions have recognised the role water plays in our well being. In
developed societies, due to past investments in water infrastructure we have
come to expect that water will be available 365 days of the year. We have
being brought up with the notion that as long as we pay for it we have the right
to consume as much as we want. Since there is no substitute to water, water
prices have not reflected its intrinsic value and traditionally is subsidised.
Con-
sequently water is cheap relative to other resource costs. This has led to global
fresh water consumption to rise faster than it is replenished. Between 1990 and
1995, fresh water consumption rose more than twice the rate of population
growth. According to a report released by the International Water Management
Institute (IWMI) at the Stockholm World Water Conference in 2006, a third of
the world’s population (roughly 2 billion people) is facing water scarcity now,
not in 2025 as earlier predictions forecasted [1]. Water scarcity is not only a
third-world problem. In recent years water scarcity have affected developed
countries too. For example, in Australia the one in a hundred year drought has
made water a political issue. It has highlighted the competing needs of
agricul-
graphically shows the available global water resources.
Table 1.1 shows that 98% of the world’s fresh water (0.5% of the total) is in
aquifers.
Freshwater – available
0.50%
Freshwater – frozen
2.50%
Seawater
97.00%
Figure 1.1 Global water resources [4]
Courtesy of the World Business Council for Sustainable Development – Facts and Trends.
Geneva, Switzerland. August 2005.
Water Conservation 3
Table 1.1 Where is this 0.5% of fresh water?
Water resource km
3
Million acre-ft Number of Olympic- Percentage
sized swimming
pools
∗
(×10
6
)
Aquifers 10000000 8107013 4000000 97.9%
Rainfall on land 119000 96473 47600 1.2%
(net of rainfall
after accounting
for evaporation)
Natural lakes 91000 73774 36400 0.89%
Man-made storage 5000 4054 2000 0.05%
population and
•
minimise the impact of climate change on water resources.
1.3 Human Need for Safe Drinking Water
and Proper Sanitation
The world’s increasing water demands are driven by an increase in global
population and urbanisation. The world’s population is expected to increase
4 A Practical Approach to Water Conservation
from approximately 6 billion in the year 2000 to 8–10 billion people in 2050,
with 90% of future population growth occurring in developing countries [6].
Over the next three decades, urban growth will bring a further 2 billion
people into cities in the developing countries, doubling their size to about
4 billion people. These cities are growing at a rate of 70 million people
per year [7].
This growth will result in the creation of mega-cities with populations in
excess of 10 million people in each city. In 1950 there was only one
mega-
city – New York. In 1975 there were 5 and by the year 2015 it is expected
that 23 cities around the globe will become mega-cities – 19 of them will
be located in developing countries. Table 1.2 shows the 10 largest cities in
the world in the year 2000.
These countries already suffer from severe water stress and myriad other
social issues. Over 1 billion people or (one in six) live without regular access
to safe drinking water. Rapid urbanisation creates squatter towns and slums.
For example, currently 40–50% of the population in Jakarta (Indonesia) and
a third in Dhaka (Bangladesh), Calcutta (India) and Sao Paulo (Brazil) live
in slums [7]. These increases in population will increase the demand for
water. Poor sanitation conditions result in increased child mortality. For
example, there is one toilet for every 500 people in the slums of Nairobi
(Kenya). Leakage rates for most of these cities’ water distribution systems are
New Delhi
Tokyo
Osaka
Dhaka
Shanghai
Mexico City
Cairo
Karachi
Bombay
Calcutta
Rio de Janiero
Sao Paulo
Buenos Aires
Figure 1.2 The global water challenge – urbanisation and freshwater stress
Source: World Business Council for Sustainable Development – Business in the World of Water. Geneva, Switzerland.
August 2006.
Water Conservation 5
6 A Practical Approach to Water Conservation
urbanisation and water stress in regions around mega-cities as a ratio of total
water withdrawals divided by estimated total availability [8].
Whilst almost all the mega-cities are predicted to suffer from water short-
ages, the problem is particularly acute in China; it is predicted that 550 cities
will experience severe water shortages [8].
1.4 Meeting Agricultural Needs
With nearly 70% of global fresh water being used for agriculture (80%
in Asia) it will be increasingly difficult to meet global food requirements
for a growing population. The development of fresh water resources for
human use has compromised natural ecosystems that depend on these
resources.
Table 1.3 shows that countries with abundant rainfall, such as in
63
71
78
4
7
6
12
5
17
21
∗
Environment flows and water supply accounts for the remainder.
Sources: World Business Council for Sustainable Development Industry. Fresh Water and
Sustainable
Development. April 1998 and Australian Bureau of Statistics Water Account
Australia
2000–01.
Water Conservation 7
Water Consumption in Australia 2000–01
Environment
Household
Other
Water Supply
Electricity and gas
Manufacturing
Mining
Agriculture
0 5000 10000 15000 20000
million m
3
water. The water used in the production process of an agricultural or
indus-
trial product is called the virtual water contained in the product [9, 10, 11].
Table 1.4 shows the virtual water requirement per kilogram of some common
agricultural products for some selected countries. For example, to produce
1 kg of beef, 13 000 L of water (or more) is required.
Table 1.4 shows that livestock products have a higher virtual water content
than cereals and this is understandable. It also shows that USA and Australia
are more efficient producers of food than India for the selected products.
Export trade in food is in fact trade in
water. When countries living in water-
stressed areas export food, they are in effect exporting water, which further
exacerbates the water shortage problem of that country. The largest of the
water exporting countries include USA, Canada, Germany and Australia.
8 A Practical Approach to Water Conservation
Table 1.4 Average virtual water content of some selected products for
some of selected countries [9, 10]
Food item Water requirement m
3
/ton
USA Australia India
Rice (paddy)
Wheat
Soybeans
Cotton seed
Beef
Pork
Poultry
Lamb
1,275
decreasing contribution that agriculture makes to the Australian economy,
the question arises whether the net outflow of 4000 GL/yr is in the nation’s
long-term interest.
Figure 1.4 shows the virtual water flows in traded crops.
Whilst the problem of under nourishment is a developing-country prob-
lem, over capacity and excess of food is a developed-country problem.
Obesity, unhealthy food habits, more convenient type foods are driving up
water demand in the world. Government subsidies also encourage
over-
production. In the Organisation for Economic Cooperation and Development
(OECD) countries, farmers receive more than one-third of their income from
government subsidies, in total over US$300 billion each year [9].
Increases in life styles in the developing countries will further increase
meat consumption which means increased water consumption compared to
a
cereals- or pulses-based diet.
1.5 The Impact of Climate Change
Much has been written about the impact of climate change. Recently there
have been a record number of reports providing evidence that climate change
is occurring and more importantly the cost of not doing anything to combat
it could cost the world trillions of dollars and the extinction of 40% of the
Water Conservation 9
Virtual Water Flows in Traded Crops
Products are transported around the world, along with the water embedded in them.
Eastern Europe
North America
Western
Europe
FSU
Central America
26
Figure 1.4 Virtual water flows in traded crops
Source: World Business Council for Sustainable Development – Business in the World of Water.
Geneva, Switzerland. August 2006.
species. The principle factors driving climate change are well-documented
global warming and greenhouse gas effect.
The question is what impact/effect climate change will have on humans,
environment, the economy and the water supplies. A wide-ranging UK study
conducted by the former chief economist of the World Bank, Sir Nicholas
Stern, is the latest and paints a bleak future if no action is taken [13].
The predicted impacts of global warming include the following:
•
Higher maximum temperatures with more hot days and heat waves in
nearly all land areas. The earth’s surface temperature has increased on
average by
06
C ever since temperature measurements were started
in the 1800s. All of the 10 warmest years have occurred since 1990
including each year since 1995. Climate models indicate a global
tem-
perature increase of
14–58
C 25–104
F by 2100 [10]. In Australia
the temperatures could increase by
1–6
•
Changes in natural water availability will affect water management,
allocations, prices and reliability [16].
•
Increase in regional conflicts. As the river flows change patterns,
regional conflicts amongst countries that share these rivers are going
to increase. There are over 2000 regional international treaties sharing
water rights in river basins. Some predict that the next world war will
be fought over water not oil.
•
Impacts on global food production due to global warming, change in
rainfall patterns and the increase in carbon dioxide levels resulting in
higher food prices. For an example, a more variable monsoon on the
Indian subcontinent can impact on the food production of a quarter of
a billion people in Bangladesh.
•
Hotter, drier summers mean increased demand for water for per-
sonal use and air-conditioning. According to a study conducted by the
CSIRO, for every degree of global warming, evaporation will increase
by 8%.
Case Study: Impacts of Drought in Australia – Grain Harvest Worst in
10 Years
Australia is heading for its smallest harvest in 10 years. Australian Bureau
of Agricultural and Resource Economics predicted that in the 2006
finan-
cial year economic growth will reduce by 0.7% points. A$6.2 billion
would be wiped from the value of farm production, a 35% decrease.
Wheat harvest alone has reduced from 20 to 9.5 million tons.
Adapted from: Sydney Morning Herald. 30 October 2006. p. 9.
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