Descz~tiation, 39 (1981) 394-&l Elsevier Scientific Publishing Company, Arnskrdam - Printed in The Netherlands

399

DESALINATION IN AUSTRALIA - PAST AND FUTURE

G.G. Fenton and J-P_ Gerofi

Solar Desalination Group, Department of Chemical Engineering

University of Sydney

ABSTRACT

Despite Australia’s vast arid areas, Australia only has a very small proportion

of the world’s installed desalination capacity_ This paper surveys the current

plants, and outlines some of the operational problems that have occurred. Demi n-

eralisation plants are also considered. The water resources of Australia are

reviewed, and areas delineated where desalination might be applicable. Within the

context of the energy sources available in different localities, the potential

applicability of various desalination technologies - distillation, RO, ED and VC -

is discussed.

INTROGUCTION

Australia is the world’s driest continent. The limited extent of its surface

water resources can be seen in Table 1, where rainfall and runoff are compared for

the six continents [ 11. Australia has not only the lowest rainfall and runoff in

proportion to its area, but also the lowest percentage of runoff to rainfall. That

is, even the proportion of water available for use from Australia’s low level of

precipitation is less than in other continents.

TABLE 1 : Rainfall and Runoff of the Continents C 11 Averase annual Runoff as a

Africa North America South America Asia Europe Australia

rainfall* Percentage of (mm) Rainfall

_ 660 660 42:

1,350 610 33: 580 40 420 13

The distribution of surface waters is quite variable across the continent as

shown in figures 1 and 2_ Except for a more marked decline in runoff towards

the inland, the rainfall and runoff patterns are quite similar. The relatively

well watered portions of the continent are the far north, the eastern and south-

eastern seaboard, and the south-western tip S and represent only a small proportion

400 FENMN??ND GSROFI

of the land mass. The bulk of the population is located in these areas. In fact

57% of the nation’s population inhabits 7 capital cities. (414 live in Sydney and

Melbourne alone). Of these capital cities only Adelaide (S.A.) and Perth (W-A3 are

like19 to have difficulty in meeting their water needs in the traditional ways for

the foreseeable future, and the other cities in general have supplies of excellent

quality fairly readily available [ 2,31.

Groundwater occurs throughout Australia, although useful supplies cannot be

tapped everywhere. Major sedimentary basins extend under 60 per cent of the con-

tinent and much of the inland is dependent on these as a source of groundwater for

stock and domestic consumption. Knowledge of Australia’s groundwater resources is

still limited.

Figure 3 shows the salinity of the groundwater where it is known, categorised into

areas with salinities in the ranges of under l,OOOppm, 1,000 - 7.000ppm, 7,000 -

14,000 ppm and greater than 14,000 ppm- In areas where different salinities are

recorded, the highest has been indicated. Aquifers are generally recharged by rain,

although the point of recharge may be a very long way from the point of use. It

should be noted that some areas, such as the southern parts of South and West

Australia, and parts of the N-T., have groundwater of very high salinity - sometimes

considerably more saline than seawater. Their particular composition often render

these waters much more corrosive and prone to scale formation than seawater.

Areas of Australia with ?ow annual rainfall (or runoff) and where either the

available bore water is saline or only seawater is available, represent the regions

where desalination of the local water may be the best means of supplying water.

Figure 4 outlines these regions, and was derived by super-imposing the appropriate

areas of Figures 1, 2, and 3. Regions with groundwater salinities less than 1,000

ppm have been excluded, even though desalination could still be needed in Some

cases. Some coastal regions have both seawater and lower salinity borewater

available. Some of these areas already have desalination facilities in operation.

Water may be needed either as potable water or for industrial and agricultural

use. The World Health Organisation’s recommended maximum potable water Salinity

is 500 ppm but this limit is considerably higher than the present norm in Australia.

Salinities for agricultural purposes can be much higher. depending on the

particular 1 and usage. Industry usually requires very pure water: a notable

example is water as boiler feed. The costs involved in any of the desalination

processes, even for brackish water, generally prohibit their use for agricultural

purposes _ In urban areas of Australia, water costs are generally low by world

standards; with excess water rates ranging around 30 cents per m’. These charges

do not necessarily represent the real cost of supplying water; for instance in

South Australia in 1979 a statewide price of 22 centssjm3 was charged, although

the mean water costs to the Government in the different State districts ranged

between SO.27 and $1.01 per m3.

FENTON AND GEZROFI 401

These costs all include both headworks and reticulation. Even the maximum cost

is below the water production cost from present seawater desalination plants.

However, it should be noted that in many areas of South Australia and Western

Australia existing surface water resources are almost fully utilized and additional

capacity can only be provided at very great capi cost- For example, a major

increase in demand at Fort Augusta could require adding to the capacity of the

pipeline system from the Murray River 3OOkm away - at considerable expense.

Adelaide also draws a large proportion of its water from the Murray River. There

are no other untapped catchments available to Adelaide and it is difficult to see

how any major augmentation to the supply could be arranged.

ENERGY SOURCES IN AUSTRALIA

(a) Electrical Power

Australia has abundant coal reserves, particularly on the Eastern seaboard, and

hence most of the nations electrical power system is coal-based. f&t of the larger

power stations are situated near the coal source , with grid connections to the

major cities. Tasmania, NSW and Victoria also have large hydro-electricity

generation systems. Despite the large distances involved, power costs in regions

serviced by the grid are relatively low with prices as low as 2 cents/kWh available

to large bulk users.

Not all areas of Australia enjoy such low power costs. Western Australia in

particular relies on diesel generators to provide power to over 40 remote towns.

South Australia’s coal reserves are of poor quality, and located in remote regions,

and the FIorthern Territory relies almost exclusively on diesel-based power. For

larger-sized diesel-generation plants, power costs of 10 - 17 cents/kWhe appJy

I 41- In remote regions, costs can be considerably higher.

(b) Thermal Energ&

Australia currently produces 65Z of its oil requirements, the remainder being

imported, however the retail price For fue7 is based on world parity prices.

Australia’s own Fields produce mainly light oils, so the heavier fuel oils are

largely imported. To provide thermal energy. fuel oils compete with natural gas

which is available in the mainland capital cities. In coastal regions fuel based

thermal energy costs about 2.2 centS/kWhth (based on Bunker C fuel oi7) but can

rise to 2.6 cents/kWhth in regions where low sulphur fuel must be used. In

remote regions - particularly towards the arid central parts of Australia - transport

costs increase the effective thermal energy cost even further.

Few remote regions are connected to a power grid system, and so rely on diesel-

generators - Hence in most such regions, waste heat from diesel jacket water and

exhaust gases is available at very low cost, however, little of this is utilized.

Another potential source of thermal energy is solar energy. Figure 5 presents

402 FEWTONANDGEROFI

the annual average insolation within Australia, and shows that most dry remote

regions enjoy a high intensity of solar radiation. Use of solar energy is an

emerging technology, but the cost of thermal energy from such systems is

presently fairly high. A notable exception is that of solar ponds, where - in

sites where they are applicable - thermal energy costs would appear to he lower

than those from fuel-based systems [ 51.

EXISTING DESALINATION PLANTS

Despite its status as the worlds driest continent, current desalination

installations in Australia represent considerably less than 1% of the total world

capacity. Table 2 is a sumnary of current Australian desalination plants; this

is based on data from 151 and also from an extensive survey conducted by the

authors. The table excludes a number of VC and MSF plants installed on Naval and

oil-dril!ing vessels and some very smzll plants. If “desalination” is extended to

cover “demineralisation”; i.e. the production of high purity water from supplies

which are generally potable, then many other large installations - almost all

ion-exchange - can be included. Table 3 is a partial listing of Australian

demineralisation facilities. Figure 6 plots the locations at most of the plants

in Table 2 and 3.

Of the desalination plants, the largest installation is that of the 2 MSF plants

at Dampier, \/.A., with to?;al capacity of 1,817 m3/day. In actual fact, these

plants, powered by diesel waste heat, have not operated at full capacity, and are

at present used only infrequently. All the other MSF plants listed are at Moomba.

S.A., servicing the natural gas processing operation there. High recirculation

rates are used, bringing the average feed salinity to 11,000 - 15,000 ppm. These

plants have been operating continuously, with regular acid cleaning every 4 - 6

weeks.

Some plants included in earlier surveys [7] have had fairly short lives due both

to the rising cost of fuel (older distillation plants were designed for quite low

PR’s) and because of high maintenance costs. An example is the 26 m3/day VC

plant installed at Rottnest Island, W-A., in 1963. The original unit broke down

continuously and had to be replaced by the manufacturer in 1964. ilver the period

1963/70 the total operating cost - excluding capital charges - average $2.09/m3,

however, over 1969/70 the operating cost was !j3.67/m3 : the plant was abandoned

in 1970. Similarly, a 27 m3/day VC plant installed on Heron Island (Queensland)

in 1968 is no longer operational. The VC plants on offshore oil platforms in Bass

Strait have been reported as needing frequent (and costly) maintenance to keep

on-line; with scaling being the main problem.

FEKQN hND GEROFI 403

TABLE 2 : AUSTRALIAN DESALINATION PLANTS

Location Operator Capacity (m3/day) m

Western Aust. Exmouth U.S. Navy 440 Dampi er Hamersley 2x 900

Amber Eucl a Hotel 6.0 RO Raw1 inna A.N. Rly. Barrow Is. UAPET z !oo Dampi er Hamersley 2x160+13 RO

+2 Agnew A. Nickel 66 Dampier C.R.A. Ltd. 0.24 z: Dampier C.R.A. Ltd. 3x 48 RO Madura Hotel Newmount 7 RO Tel fer Gold 68 RO Denham Govt. 75 -+ 75 RO Karratha Govt. Kwi nana State Elect - Perth Q-E-Medical Fremanti e Hospital Useless Loop Shark Bay Salt Lake McLeod Texada Sal t Coral Bay Motel ,C’van

RO 72;

45 :: 5 RO

100 RO 23 RO 3? RO

South Aust. Moomba Santos 228 MSF Moomba II 244.8 MSF Moomba II 547.2 MSF Cook A.N. Rly 20 RO

Port Lincoln Govt.MeatWorks 114 RO Adelaide Fl i nders Med _ CooberPedy Govt. 68.: ::

Port Augusta A.N.R!y ? RO Yal ata Abo.Res. 7 RO CooberPedy Govt- 68.2 RO Manguri A.N.Rly 60.0 RO LeighCreek ETSA 700 RO Moon&a Santos 54T MSF

Vi ctori a Bass Strait Victoria Victoria

27.3 9.1

36.4 vc Victoria 36.4 vc Victoria Vi ctori a 5::: ;: Barracouta- Platform Esso 18.2 t+zlbourne Govt.

1::; ::

Mei bourne R.M.I.T. RO Tuna- Platform Esso 18.2 vc Mackerel - Platform Esso 18.2 vc Snapper- Platform Esso 18.2 vc

Manufacturer

Ioni cs trlei r Uestgarth Havens Intl .

0 Permuti t

II

Clough&Sons Pet-m&it

II II II

Aqua-Chem II II

Paterson Candy

Permuti t ,I

I.B.C.Fluid Systems

1-B-C. I.B.C. Permuti t Aqua-Chem

Feedwater commiss- Salinity(ppm) ioned

1.700 1967i 35,000 1968

16,000 1968 2,500 1969 2.500 1973 1,000 1975+

4,500 1976 1976 1976

13 .ooo 1976 2;ooo 1976 5,000 1977 1 .ooo 1980

750 1980 750 1980 750

5,000 Bore Bore

1980

2 .ooo-4,000 1969 I, 1973 II 1976

9,000 1976

BOO 1976 700 1978

17,200 1980

8,000 Bore

17,200 1981 8,200 1981 5,000 1981

2 .ooo-4,000 1981

35,000

35,000

II 35,000 1975 Permuti t 100 1975

II 26 1976

Aqua-Chem

II Mechanical Equip_(MECO)

35,000

35,000

35,000

1977

1977

1980

1967 1967 1968 1970 1970 1970

404 FENTON AND GE!2OFI

TABLE 2 : Ausm-v_~AN DESALINATION PLANS (CONTINUED) Victoria Flounder- Esso 18.9 RO Koomey Platform Victoria 54.6 vc Aqua-Chem Port Fairy Glaxo 4.5 RO Permutit West. Kingfish Esso 18.2 vc MECO Platform Cobla Platform Esso 18.2 vc MECO Fortescue Platform Esso 18.2 vc MECO Melbourne Esso 65.5 RO 1-B-C.

35,000 1980

1980 900 1980

35,000 1981

35,000 1981

35,000 1981 17,200 1981

New South Wales Sydney Ciba Geigy z-i Pennutit 100 1973 Maitland Aust.Coal Ind. ,I

65 l-4,000 1974

Tarago Woodland Mines II 1,000 1977 Tamworth Hospital 9 II 150 1977

Queensland Barrier Reef 54.6 vc Aqua-Chem 35,000 1970 Oakey Army 46.0 RO Permutit 500 1974 Blackwater Old. Coal 11.0 RO Permutit 2.000 1976 Brisbane 91.0 R" 1-B

II- C. -300 1977

Brisbane 6.8 RO 300 1978 Marlborough Shire 77.4 RO ,I 1,760 1978 Barrier Reef 6.0 RO " 35,000 1979 Tarong 128.7 RO " 1,920 1980 Heron Is. P&O Hotels 30.0 RO " 35,000 1980

rdnrthPrn Territory Tennant Creek Peko Wallsend 100 RO Permutit 1,900 1980

A large number of RO plants have been installed fairly recently, although some

older plants are still operational: a 5 m3/day plant at Eucla, W.A. has been

operating for 13 years on 16,000 ppm feedwater, although the operators report high

module replacement costs. Earlier RO plants installed by the Australian National

Railway at Rawlinna and Cook have had problems in achieving design capacity and

product purity. This was found to be due to poor pretreatment, and a revised

pretreatment method based on the plant at Manguri (about to be conmissioned), will

hopefully solve the problem. The original plant at Rawlinna, installed in 1969,

was largely replaced in 1975, using a more modern type of membrane. The RO

plants operated at Coober Pedy, S-A., with a difficult 18,000 ppm feed,have also

exhibited high costs attributed to poor pretreatment systems. Water from the

older plant is reported to cost S8.24/m3 although it is sold to the public at

about half this price.

FENTON AND GEROFI 405

Location

TABLE 3 : SOME AUSTRALIAN ION EXCHANGE PLANTS Cactaci tv

CarltonWnited Brew.

Operator

State Elect.

ICI Aust.Newsprint

II

Lurgi

II

Ranger Uranium

1,

State Elect.

I‘

II

II

,t

I,

,I

I,

Dept. of Works

ICI

State Elect.

Nt _ Newman

Dow Chem. fit. Isa Mines

I‘

State Elect. II

Monsanto State Elect . II

II II I‘ ,I I, II li II II I, II **

Monsanto Amp01

State Elect. II I# L1 ,I

Monsanto State Elect.

‘I

im’/dayi Manufacturer Commissioned

East Perth W.A. Wangi NSW Bunbury W.A. Mt. Gambier S.A. Sth.Fremantfe W.A. Wal lerawang NSW Tennyson Q’ld, Port Augusta S.A. Darwin, N-T. Nagwarry S.A. Altona Vie. Mica Creek Q'ld. Mt. Isa Q’ld Vales Point NSil Pyrrnont NSW Footscray Vi c. Calcap Q’ld Munmorah NSW Muja W.A. Rhodes NSW Torrens Is. S.A. Swanbank Q’ld Tennyson S.A. Vales Point NSW Torrens Is- S.A. Collinsville Q'ld. Munmorah NSW Singleton NSW Morwell Vie. Singleton NSW Footscray Vie. Lytton Q’ 1 d Collinsville Q’ld. Wallerawang NSW Gladstone Q’ld Torrens Is. S.A. Kwinana W-A. Footscray Vie. Vales Point NSW Yallourn Vie. Melbourne Vie. Botany NSW Albury NSW &r-well Vie. Jabiru N-T. Gladstone Q’ld Eraring NSW Tarong Q’ld Loy Yang Vie. Osborne Vie Mt. Newman W-A.

590 345 860 164 540 164

590 + 110 540

19,872 15,552 1,360 680 810

545 + 182 1,370 820 430 540 820 540 680 540

2 x 160 1,380 16,356 1,100 4,600 810

2,940 164

1,140 2.050 910

1,140 1,600 2,950 1,900

Permuti t I, ,I II I‘ I, I,

N.E.I.JohnThompson Permuti t

li

N-E-1. Qermuti t

11 I, II

N-E-1. Qermutit

,I I*

N.E.I. II

Pet-m&it I, II

N-E-1. II

Permuti t It

N-E-1. ‘I I,

Permuti t

2,290 1,814 2,160

75 380

2.040 6,120 3,840

1956 1956 1956 1956 1957 1958 1960 1960

1960 - 68 1961 1961 1961 1961 1962 1963 1963 1965 1965 1965 1966 1966 1966 1966 1967 1968

1968, 69 1969 1969 1970 1970 1970 1972 1973 1974 1974 1974 1975 1976 1977 1978 1978 1979 1980 1980 1980 1980 1981 1981

600 500

I.C.I/CSIRO*

* Demonstration Plant - “Sirotherm” Process

406 FENTON AND GJZROFI

Tab1 e 2 includes only one ED plant. Particularly with difficult, lower

salinity borewaters, processes such as the ED reversal system - with their rela-

tively modest pretreatment requirements - might be thought to be competitive with

RO systems. A proposed desalination installation at the tourist village of Yulara

in the N.T. (2 plants of 380m3/day capacity, feedwater 1,480ppm) is presently out

for tender, and an ED system could quite possibly be chosen.

Of the Smineralisation plants in Table 3, most are of the fairly conventional

ion exchange type. The 600m3/day plant at Osborne, S.A. (a demonstration plant)

uses the “Sirotherm” process for thermal regeneration of the resin [8]. This

process has not quite lived up to its earlier expectations because it has been

found impractical to treat waters containing calcium salts, and hence where

calcium is present a first stage to remove the calcium is needed 161. Nevertheless

the Sirotherm process could become quite attractive for applications in the low

salinity large volume range, particularly for low-calcium feedwaters.

POSSIBLE APPLICATIONS

(1) Distillation

It is of interest that no multiple effect plants appear in Table 2. This

should be considered in context: not a single new distillation application has

been implemented in recent years - the newer MSF plants at Moomba were virtually

add-ons to existing units. Potential users appear to have seen the Moomba plants

as a special case because of the cheap natural gas available, and - considering

also the unspectacular performance of the Dampier MSF plant - turned to other

technologies such as RO which was being extensively marketed at that time. The

aurhors feel that RO has been somewhat oversold in Australia, and that potential

users have not kept up with developments in the distillation field. As an

example, water costs using a modern VTE or HTE distillation plant at Coober Pedy

would surely be much less than the $8.24/m currently applicable to the RO plant

now in operation. Even a solar-driven plant could produce water at costs below

this 19, 101.

Developments in multi-effect evaporator (MEE) distillation plants have led to

systems with cheaper capital costs than MSF plants i 111. In addition, MEE plants

can be designed for higher PR’s and require less pumping power than MSF processes.

One particular combination that would appear attractive in more remote regions is

the coupling of waste heat from diesel generators (the predominant source of

electrical power in such regions) with MEE plants. A number of such systems are

available in a range of sizes 112, 131 , with PR’s of 4 - 6.5. Since the thermal

energy for such systems is virtually free, overall water costs should be quite low

and hence very competitive with RO systems - particularly for higher salinity

E-IBTON AND GERmI 407

feedwaters _ If water demand is badly matched to the power demand, then a fuel/

waste heat or possibly a solar energy/waste heat combination might prove cost-

effective.

Where waste heat is not available, the availabilfty of natural gas may make

future distillation plants competitive in some areas. Alternatively, use of solar

energy to drive MEE plants is now approaching economic feasibility for remote

regions f either as collector/plant combinations or - for larger sizes - solar

pond/plant combinations [ 9, IO] . For capacities above about ZOm=/day, collector/

plant combinations produce cheaper water than solar stills [ 91.

For large-scale water requirements in urban environments - such as Perth or

Adeal ide - the most likely source of energy is from power stations, either as

electrical energy or as “waste” heat. The cost of water from combined power/

desalination complexes such as those prevalent in the Middle East is, however,

quite high, and - in any case - the existing Australian power stations have not been built to acconnmdate such a dual role. A recent process which both promises

cheaper water and would cause least disruption to the existing power generation

facilities is Nord Aqua’s Waste Heat Desalination (WHD) system [13, 151. This

system has as its heat source the outlet seawater used for cooling in such processes

as power stations, oil refineries, metallurgical plants, fertilizer plants, fer- mentation plants, etc. This water is generally warmed only about 10°C. but is

available in vast quantities: about 60% of the thermal input to power plants

exits as waste heat. Plants using such small temperature differences to drive

the desalination process have a high pumping power requirement (since a circulation

t-ate Of 100 times that of the product rate is required} and have to remove from

vacuum very large volumes of non-condensible gases. The WHO design makes provision

for these complications and, in areas where such waste heat is available, is

very competitive with conventional distillation processes for desalination of

seawater [ 151: for a given capacity the capital costs are similar, pumping power

costs are comparable, maintenance and labour costs are simjlar, but the thermal

energy cost - which can be over half of total water cost in conventional plants -

is zero for the WHD process.

(2) Reverse Osmosis

While it was stated earlier that RO may have been “oversold” in Australia, there

are many potential applications where RO would be the main contender. The main

problems with RO appear to be in the pretreatment system, with poor pretreatment manifesting itself as high membrane replacement frequency. We see the most cost-

effective applications of RO as:

(a) desalination of brackish borewater (say to 7,OOOppm salinity) - PartiCUlarlY

waters with relatively low silica. Fe, Mn and Aelevels (6) small scale desalination of surface waters or potable water to produce a

very pure product (for large scale applications, ion exchange in more popular)

408 FENTONANDGEXOFI

(c) seawater desalination in regions with either cheap electrical power or where

space considerations are predominant (e.g. for offshore oil and gas platforms)

In most areas of Australia with very brackish borewater (7,000 - 35,000 + ppm),

the authors feel that waste heat

cheaper water. If waste heat is

choice.

processes, described above, will generally produce

unavailable, then RO could still be the best

Solar powered RO is possible, however, the most often-quoted such system -

photovoltaic cells plus RO - has been shown to be unattractive relative to other

solar alternatives for most salinities [ 101, and certainly uneconomic at present

relative to conventional RO using diesel-powered generators.

(3) Electrodiaiysis

As outlined earlier, modern ED systems such as EDR are much less sensitve to

feedwater composition and so can tolerate much simpler water pretreatment schemes.

Since groundwaters in many regions of Australia require extensive pretreatment for

RO, ED should be quite competitive, particularly for lower salinities ( < 3,OOgppm).

ED is not applicable where very pure product water is required, since the amount

of electric current required depends on the amount e f dissolved salt to be removed

and pure water has a very high electrical resistance.

By using a number of stages in series, ED has also been used to desalinate

seawater, however, the cost has been very high. More recent work, particularly on

higher temperature membranes, has increased the range of ED processes, and

improvements in the economics of ED desalination of seawater have been reported

E 161. The cost of desalinating seawater by ED is stil’l considerably higher

than for either distillation or RO. Solar powered ED, like solar powered RO, is

possible but unlikely to be economic.

(4) Vapour Compression

VC is essentially a distillation process, but has been listed separately because

the majority of VC processes require mechanical energy for the compressor, usually

supplied electrically. For small, packaged systems the major advantages of VC

over RO or ED systems are that (a) only minor pretreatment is needed (screening,

chlorination, scale control additives) (b) high product purity is achieved, (c)

very high concentration ratios can be achieved (useful if effluent disposal is a

problem [ 111, and (dj a wide range of feed salinities can be tolerated. However,

because the power requirements for VC are independent of salinity, for low salinity

waters, RO and ED use less power.

For seawater desalination, the power costs for VC and RO are not very different,

however, at least one VC manufacturer ctaims that VC is capable of lower power

consumption C173. Hence for smatt capacity seawater units, such as for offshore

pt atforms VC and RO are in direct competition.

Thermocompression variants of VC plants are available, irhere compression is

accomplished by use of jet ejectors driven by mid-pressure steam. Because jet

ejector5 are fair@ inefficient , SOme of these systems actually have relatively

low energy efficiency. Atso, because mid- rather than few-pressure stean is

required, it is unlikely that waste heat or solar energy could be used as a cheap

source of heat.

One possible extra application of the VC process might be as a portable truck-

rrmunted plant. Many outback areas of Australia are subject Co severe droughts. and

such a unit could be #moved from tavvn to town to at least provide drinking water

for the inhabitants. A VC p‘fant is the obvious choice for such an application

because of the advantages (a) and {d) listed above.

CONCLUSIONS

fiIost of Australia’s major popu?ation centres wit7 be welf supp’lied with fresh

water from conventicnal sources for the foreseeable future. The significant

exceptions are Adelaide and Perth. Several smaller settlements which support

agri cu? tural , mining or railway conmunities are less fortunate than the big cities. For such towns, particularly in S-A. and W-A., desa7ination could in future be

the most cost-effective means of supp‘lying fresh water.

Up to the present, Australian experience with distillation plants has been very

limited and not very favourabfe. Vapour compression plants have been used more

widely, but have suffered scaling problems. Reverse osmosis plants are now the

most co-n type of desatination p7ant installed and are also used in some situations

where other types of processes could well have done the job.

Distillation in Australia can have a future, especially if modern MEE plants

are used and if cheap thermal energy from waste heat is avai7ab7e. Sa7ar ponds

represent another potential source of cheap energy for distillation. The salinity

at which distillation becomes mare attractive than RO depends on energy costs and

on the nature of the feedwater. but there are several tocations in Australia where

distillation plants would be more cos t effective than the existing RO plants,

Low grade waste heat is an attractive means of desalinating high sa7inity waters

where large power stations or other industrial plants with similar cooling

requirements are located.

V& and ED also have potential applications in certain situations_ ion exchange

should continue to find a market for demineralising low salinity waters.

The So’lar Desalination Group is supported by a grant from Saudi Arabian interests,

administered by the Science Foundation for Physics, University of Sydney- This

financia? assistance is gratefully acknowledged.

410 FESTOIi AND GEROFI

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2.

3.

4.

5.

6.

7.

8.

9.

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Herbert, L.S. and Moffatt. D.H. “Desalination - A Survey of Australian Plants”, Dept. of National Development, Australia (1970). Stephens, G.K. and Bolto, B.A. “Gesalination by Thermally Regenerated Ion- Exchange Resins”, PACE. ~21-26, June (1977). Gerofi, J-P., Fenton, G.G. and Mannik E., “Solar Distillation - The Solar-Driven Case”, IDEA Conference, Bahrain (1981).

lO.Gerofi, J-P. and Fenton, G-G., “Comparison of Solar RO and Solar-Thermal Desal- ination Systems”, IDEA Conf. Bahrain (1981).

ll.Cox, B. “Trends in Desal ting" , Pure Water, Vol. 10 (I), ~8-10, March-April (1980) 12.Valmet Oy, Brochure 8139, Finland. 13_Atlas-Danmark, Brochure 8469e, Denmark. 14.Saari, R. “Desalination by Waste Heat”, Proc. 6th Int. Symp_ on Fresh Water

from the Sea, Athens Vol. 1 p297-304 (1978). 15.Kranebitter F., “Clean Water from Waste Heat”, Proc. 6th Int. Symp. on Fresh

Water from the Sea, Athens Vol. 1, p283-290 (1978). 16.Lundstrom, J-E. “Desalting Seawater to Less than 4ppm by ED”. Desalination Vol.

32, p259-277 (1979). lSI.Matz, R., and Fisher U. “A Comparison cf the Relative Economics of Sea Water

Desalination by VC and RO for Small to Medium Capacity Plants”, 7th Int. Symp. on Fresh Water from the Sea, 1 p339-350, Amsterdam (1980).

Figure 1. Australia - Annual Figure 2. Australia - Annual Rainfall - mn. runoff - mn.

FENTON AND GEIROFI

Figure 3 (right). Australia - Groundwater saJinity - PPm.

Figure 4 (beJow). Areas in which desalination may be applicable for water supply.

Figure 5. Australia - average daily globa’l insoJation - kNh/m’ &J/m’).

0 looo-7cOo

t2g 7ooo-l4oOG ‘.’ B?

f 63 >54ooO

Figure 6. Location of existing deselination plants.