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Case study — wastewater reuse in Limassol as an alternative water source
~.
,~,~. ,.'~
DESALINATION
l Desalination 138 (2001) 55-59
ELSEVIER
Case s t u d y -
www.elsevier.com/locate/desal
wastewater reuse in Limassol as an alternative water source Iacovos Papaiacovou
Sewerage Board of Limassol - Amathus, 76 Franklin Roosevelt, Block A, P. O. Box 50622, 3608 Limassol, Cyprus Tel. + 357 5 881888; Fax +357 5 881777; e-mail: sbla@cytanet, com.cy
Received 15 March 2001; accepted 29 March 2001
Abstract The wastewater reuse system of Limassol, the second largest urban area of Cyprus, with about 200,000 inhabitants, is in operation since 1995. The high quality effluent with an annual flow of about 3.5 million m 3 is fully recycled and used for many purposes such as groundwater recharge, restricted irrigation such as public amenity areas, golf courses, etc., but excluding vegetable and similar irrigation. Wastewater reuse has the main advantage of environmental protection and upgrading whilst at the same time it offers an alternative water resource, with a marginal cost much lower than the cost of desalinated water. The marginal cost for tertiary treatment is also much less than the cost paid for dam water or desalinated water. As a result, recycled water provides the potential for the utilization of the national water resources in the most economical and efficient way, providing to the national economy great savings in real terms. In conclusion the Limassol reclaimed water reuse scheme has demonsa'ated in practice that domestic wastewater is a valuable resource which can and should be used in order not only to combat the water shortage in our country in an economical way, but also to upgrade and maintain the environment which is constantly under tremendous pressure and violation. Keywords: Wastewater reuse; Limassol
1. The Sewerage Board of Limassol Amathus (SBLA) The original Master Plan for the Sewerage and Drainage Project o f the Town o f Limassol,
was completed in 1974 and implementation was scheduled to start in the same year. The events of 1974 delayed the implementation o f the project and in view of the dramatic changes in population density and the expansion o f the residential pro-
Presented at the European Conference on Desalination and the Environment." Water Shortage, Lemesos, Cyprus, 28-31 May 2001.
0011-9164/01/$- See front matter © 2001 Elsevier Science B.V. All rights reserved PII: S 0 0 1 1 - 9 1 6 4 ( 0 1 ) 0 0 2 4 4 - 2
56
I. Papaiacovou / Desalination 138 (2ooo 55-59
perties in the area due to the massive influx of refugees, the study was updated in 1977. Implementation was then further delayed due to the strong opposition of the communities in the western side of Limassol, as to the location of the Sewerage Treatment Plant. Then, the study was updated again in 1979, in 1984 and in 1989 respectively. Eventually, construction works started in 1992. The Sewerage and Drainage System of Limassol Amathus (SBLA), the largest in Cyprus is being developed in phases. The population which is currently served, is about 70,000 people and at the ultimate stage the number of people to be served is expected to reach 200,000, i.e. the whole of Limassol Greater Area. Phase A of the Project which has been set into operation in 1995, covers the whole tourist area along the coast, from west to east and consists of the following main components. • A sewage network of about 180 km • Six large pumping stations • A tunnel of about 800m long • A sea outfall for emergency situations • A secondary treatment plant • A tertiary trealment plant The total cost of Phase A of the project including the tertiary treatment plant is about US$90 million. Phase B of the project is currently under construction and it is expected to be completed in stages. The first stage which is now under construction is scheduled to be completed by 2003 and it is expected to add an additional sewerage network of about 130km and to serve at about 30,000 additional people. A wastewater reuse system is also now in operation. On completion of the whole project the ultimate cost for the sewerage treatment and water re-use scheme is expected to exceed US$180 million. The wastewater treatment plant facilities provide grit, oil grease and large solids removal
in its primary processes, followed by conventional secondary activated sludge treatment. The sludge is anaerobically digested and dewatered on belt presses. Gas produced in the digestion process will be used to heat the digesters. The secondary treatment plant was designed to produce an effluent with a 5-day biochemical oxygen demand (BOD5) of 20mg/l and total suspended solids (SS) of 20mg/l. The mean flow rate at the ultimate stage will be 48.205mVd. Currently, the sewage average flow is about 10.000 mVd. Tertiary treatment is achieved through sand filtration and chlorination process. The biological load of the effluent achieved after the tertiary treatment is less than 10mg/l of BOD5 and considerably less than 10mg/l of SS. The quality of the tertiary treated effluent, which is produced by the system, is of very high standards and well within the requirements of the European Union requirements as specified by the applicable guidelines, regulations and standards.
2. Project objectives Designed to meet the sewerage and drainage needs of the area up to the year 2010, the project comprised the first phase of development of a two-phase sewerage system and high priority drainage works. We believe that the main objectives of the project have now been accomplished. The main objectives that have been established and satisfied can be summarised under the following headings: (a) To provide a safe and reliable system for the disposal of human, commercial and industrial wastewater and thereby eliminate the nuisance and health risks, including the threat to the area's water supply and important tourist industry. (b) To provide key elements of a storm water drainage system in areas subject to severe flooding during the rainy season.
L Papaiacovou / Desalination 138 (2001) 55-59
(c) To contribute to improved environmental management by identifying and promoting the optimum reuse of sewage effluent and sewage sludge in the project area. (d) To strengthen the institutional capacity and efficiency of the SBLA Five years of operation have demonstrated how much this project was needed for Limassol and how can, treated effluent be reused effectively and efficiently, offering great quantities of water for many uses.
3. Wastewater reuse
The rapid development in the tourist industry and the steep rise in the standard of living in Cyprus have caused an unprecedented increase in the demand for fresh water. The water demand in the Cyprus market can be distinguished in three main sectors. • Demand for agriculture • Demand for industry • Demand for household or domestic use. The quality of water required for each of the above sectors varies according to its intended use. For example demand for domestic use requires water of the highest possible quality, whereas demand for agriculture can be satisfied with less quality water. The basic sources on water supply in Cyprus are water dams and ground water. Recently as a result of the water shortage in Cyprus, two new sources of water supply are being developed rapidly, namely, desalination and the wastewater reuse. The wastewater reuse in Cyprus is a very promising source. Wastewater reuse has started some years ago but its extent was very limited. It was, started in the 1980's with small treatment plants in large hotels. The treated effluent was used mainly for their gardens. In 1995 the
57
sewerage treatment plant of Limassol started its operation and nowadays the entire treated effluent is reused mainly for agriculture and also for gardening purposes in tourist resorts. The total flow of the treated effluent is about 3.5million m3/year, which in relative terms cannot be considered as huge, but on the other hand it provides a promising alternative source of water which shows that, in the long run, treated effluent can contribute substantially, to the solution of the water shortage in Cyprus. It is expected that by the year 2005, the flow of treated effluent will be reaching 8-9million m3/year, whereas at the ultimate stage when the system is fully developed, the annual flow will exceed 11 million m~/year, which is a substantial quantity for our country. As mentioned before, the quality of the treated effluent which is currently produced is extremely high and the current effluent characteristics can meet the most strict effluent requirements and standards in most countries. The tertiary treated effluent is delivered to the Water Development Department of the Ministry of Agriculture which has the responsibility for the distribution and sale of the water to the various users. A conveyor and distribution network has been constructed by the Government which includes a main conveyor pipe of about 20km long and, a number of pumping stations and reservoirs, transferring the treated effluent to the western side of Limassol where, it is reused for irrigation, gardening and for groundwater enrichment. In the immediate future, tertiary treated effluent will be used in golf courses in the area around Limassol.
4. Operation costs
Total operation costs and total tertiary operation costs for the period of 1995-2000 are presented in Tables 1 and 2.
58
I. Papaiacovou / Desalination 138 (2001.) 55-59
Table 1 Total operation cost for the period 1995-2000: secondary and tertiary treatment cost
1995 C£ Operation cost Less Government contribution Tertiary treatment Depreciation Total cost including depreciation Annual flow
1996 C£
1997 C£
1998 C£
1999 C£
2000 C£
210,805 (62,000) 148,805
663,338 (121,000) 542,338
760,437 (123,000) 637,437
700,455 (116,000) 584,455
789,315 (128,000) 661,315
961,200 (135,000) 826,200
1,539,114 1,687,919
2,027,531 2,569,869
1,978,442 2,615,879
2,013,482 2,597,937
1,991,496 2,652,811
2,031,000 2,857,200
500,000
2,452,000
2,984,000
3,024,000
3,139,000
3,146,000
Cost per m 3, cent/m 3 Including depreciation Excluding depreciation
337.6 30.0
104.8 18.4
87.7 21.3
85.9 19.3
87.3 21.1
90.8 26.3
Year 1995 was the first year of operation and operation costs relate only for 5.5 months
Table 2 Total tertiary operation cost for the period 1995-2000
1995 C£
Operation cost Depreciation Annual flow Cost per year, cent/m 3
1996 C£
1997 C£
1998 C£
1999 C£
2000 C£
62,000 121,000 123,000 116,000 128,000 135,000 138,000 138,000 1 3 8 , 0 0 0 138,000 138,000 138,000 200,000 259,000 261,000 254,000 266,000 273,000 500,000 2,452,000 2,984,000 3,024,000 3,139,000 3,146,000 40.0 10.5 8.7 8.3 8.5 8.7
5. Advantages and benefits of wastewater reuse in Cyprus
The cost of production for the tertiary treated effluent is much lower than the desalinated water. It is estimated that the marginal cost of the tertiary treatment effluent is currently about 9 cent/mL O f course the average cost of the secondary treated effluent is not taken into account for comparison purposes, because it is considered that secondary treatment process is unavoidable for environmental and other hygienic reasons. Secondary trealment
of municipal and industrial wastewater is a must and should be there in any case. ° With the wastewater reuse the water resources are used more efficiently and more cost effectively. The treated effluent is used mainly for the less demanding uses o f agriculture and therefore fresh water of the best quality can be saved for domestic use. • Huge savings are achieved in the water resources because traditionally wastewater usually is disposed directly to the sea. • In parallel to the above, it offers the most environmental friendly water source, because,
I. Papaiacovou / Desalination 138 (2001) 55-59
if used properly it resolves environmental problems caused by untreated wastewater on the one hand and on the other it reduces the constant and continuing depletion of ground water. 6. Conclusions
The general conclusion is that the solution of the problem of water shortage cannot be achieved in the most efficient way, through the continuous use of natural water from dams or groundwater or desalinated water. The treated effluent offers a tremendous opportunity not only to contribute to the solution of the problem but also to the upgrading and protection of our environment, nowadays facing fatal threats.
59
The construction and operation of central sewerage systems not only in the large towns in Cyprus, but also in all the communities should be the first priority of the decision makers, merely because of its dual effect, i.e. firstly that of environmental protection and upgrading and secondly that of the potential of more efficient utilisation of the national water resources. Of course demand for water cannot be satisfied entirely by treated wastewater. In order to satisfy the water demand in Cyprus desalination is unavoidable. So, if a combination of natural fresh water, treated effluent and desalinated water is used, then a most efficient and cost effective use of the natural resources will be achieved with the average cost of water in the national economy substantially reduced.
,~,~. ,.'~
DESALINATION
l Desalination 138 (2001) 55-59
ELSEVIER
Case s t u d y -
www.elsevier.com/locate/desal
wastewater reuse in Limassol as an alternative water source Iacovos Papaiacovou
Sewerage Board of Limassol - Amathus, 76 Franklin Roosevelt, Block A, P. O. Box 50622, 3608 Limassol, Cyprus Tel. + 357 5 881888; Fax +357 5 881777; e-mail: sbla@cytanet, com.cy
Received 15 March 2001; accepted 29 March 2001
Abstract The wastewater reuse system of Limassol, the second largest urban area of Cyprus, with about 200,000 inhabitants, is in operation since 1995. The high quality effluent with an annual flow of about 3.5 million m 3 is fully recycled and used for many purposes such as groundwater recharge, restricted irrigation such as public amenity areas, golf courses, etc., but excluding vegetable and similar irrigation. Wastewater reuse has the main advantage of environmental protection and upgrading whilst at the same time it offers an alternative water resource, with a marginal cost much lower than the cost of desalinated water. The marginal cost for tertiary treatment is also much less than the cost paid for dam water or desalinated water. As a result, recycled water provides the potential for the utilization of the national water resources in the most economical and efficient way, providing to the national economy great savings in real terms. In conclusion the Limassol reclaimed water reuse scheme has demonsa'ated in practice that domestic wastewater is a valuable resource which can and should be used in order not only to combat the water shortage in our country in an economical way, but also to upgrade and maintain the environment which is constantly under tremendous pressure and violation. Keywords: Wastewater reuse; Limassol
1. The Sewerage Board of Limassol Amathus (SBLA) The original Master Plan for the Sewerage and Drainage Project o f the Town o f Limassol,
was completed in 1974 and implementation was scheduled to start in the same year. The events of 1974 delayed the implementation o f the project and in view of the dramatic changes in population density and the expansion o f the residential pro-
Presented at the European Conference on Desalination and the Environment." Water Shortage, Lemesos, Cyprus, 28-31 May 2001.
0011-9164/01/$- See front matter © 2001 Elsevier Science B.V. All rights reserved PII: S 0 0 1 1 - 9 1 6 4 ( 0 1 ) 0 0 2 4 4 - 2
56
I. Papaiacovou / Desalination 138 (2ooo 55-59
perties in the area due to the massive influx of refugees, the study was updated in 1977. Implementation was then further delayed due to the strong opposition of the communities in the western side of Limassol, as to the location of the Sewerage Treatment Plant. Then, the study was updated again in 1979, in 1984 and in 1989 respectively. Eventually, construction works started in 1992. The Sewerage and Drainage System of Limassol Amathus (SBLA), the largest in Cyprus is being developed in phases. The population which is currently served, is about 70,000 people and at the ultimate stage the number of people to be served is expected to reach 200,000, i.e. the whole of Limassol Greater Area. Phase A of the Project which has been set into operation in 1995, covers the whole tourist area along the coast, from west to east and consists of the following main components. • A sewage network of about 180 km • Six large pumping stations • A tunnel of about 800m long • A sea outfall for emergency situations • A secondary treatment plant • A tertiary trealment plant The total cost of Phase A of the project including the tertiary treatment plant is about US$90 million. Phase B of the project is currently under construction and it is expected to be completed in stages. The first stage which is now under construction is scheduled to be completed by 2003 and it is expected to add an additional sewerage network of about 130km and to serve at about 30,000 additional people. A wastewater reuse system is also now in operation. On completion of the whole project the ultimate cost for the sewerage treatment and water re-use scheme is expected to exceed US$180 million. The wastewater treatment plant facilities provide grit, oil grease and large solids removal
in its primary processes, followed by conventional secondary activated sludge treatment. The sludge is anaerobically digested and dewatered on belt presses. Gas produced in the digestion process will be used to heat the digesters. The secondary treatment plant was designed to produce an effluent with a 5-day biochemical oxygen demand (BOD5) of 20mg/l and total suspended solids (SS) of 20mg/l. The mean flow rate at the ultimate stage will be 48.205mVd. Currently, the sewage average flow is about 10.000 mVd. Tertiary treatment is achieved through sand filtration and chlorination process. The biological load of the effluent achieved after the tertiary treatment is less than 10mg/l of BOD5 and considerably less than 10mg/l of SS. The quality of the tertiary treated effluent, which is produced by the system, is of very high standards and well within the requirements of the European Union requirements as specified by the applicable guidelines, regulations and standards.
2. Project objectives Designed to meet the sewerage and drainage needs of the area up to the year 2010, the project comprised the first phase of development of a two-phase sewerage system and high priority drainage works. We believe that the main objectives of the project have now been accomplished. The main objectives that have been established and satisfied can be summarised under the following headings: (a) To provide a safe and reliable system for the disposal of human, commercial and industrial wastewater and thereby eliminate the nuisance and health risks, including the threat to the area's water supply and important tourist industry. (b) To provide key elements of a storm water drainage system in areas subject to severe flooding during the rainy season.
L Papaiacovou / Desalination 138 (2001) 55-59
(c) To contribute to improved environmental management by identifying and promoting the optimum reuse of sewage effluent and sewage sludge in the project area. (d) To strengthen the institutional capacity and efficiency of the SBLA Five years of operation have demonstrated how much this project was needed for Limassol and how can, treated effluent be reused effectively and efficiently, offering great quantities of water for many uses.
3. Wastewater reuse
The rapid development in the tourist industry and the steep rise in the standard of living in Cyprus have caused an unprecedented increase in the demand for fresh water. The water demand in the Cyprus market can be distinguished in three main sectors. • Demand for agriculture • Demand for industry • Demand for household or domestic use. The quality of water required for each of the above sectors varies according to its intended use. For example demand for domestic use requires water of the highest possible quality, whereas demand for agriculture can be satisfied with less quality water. The basic sources on water supply in Cyprus are water dams and ground water. Recently as a result of the water shortage in Cyprus, two new sources of water supply are being developed rapidly, namely, desalination and the wastewater reuse. The wastewater reuse in Cyprus is a very promising source. Wastewater reuse has started some years ago but its extent was very limited. It was, started in the 1980's with small treatment plants in large hotels. The treated effluent was used mainly for their gardens. In 1995 the
57
sewerage treatment plant of Limassol started its operation and nowadays the entire treated effluent is reused mainly for agriculture and also for gardening purposes in tourist resorts. The total flow of the treated effluent is about 3.5million m3/year, which in relative terms cannot be considered as huge, but on the other hand it provides a promising alternative source of water which shows that, in the long run, treated effluent can contribute substantially, to the solution of the water shortage in Cyprus. It is expected that by the year 2005, the flow of treated effluent will be reaching 8-9million m3/year, whereas at the ultimate stage when the system is fully developed, the annual flow will exceed 11 million m~/year, which is a substantial quantity for our country. As mentioned before, the quality of the treated effluent which is currently produced is extremely high and the current effluent characteristics can meet the most strict effluent requirements and standards in most countries. The tertiary treated effluent is delivered to the Water Development Department of the Ministry of Agriculture which has the responsibility for the distribution and sale of the water to the various users. A conveyor and distribution network has been constructed by the Government which includes a main conveyor pipe of about 20km long and, a number of pumping stations and reservoirs, transferring the treated effluent to the western side of Limassol where, it is reused for irrigation, gardening and for groundwater enrichment. In the immediate future, tertiary treated effluent will be used in golf courses in the area around Limassol.
4. Operation costs
Total operation costs and total tertiary operation costs for the period of 1995-2000 are presented in Tables 1 and 2.
58
I. Papaiacovou / Desalination 138 (2001.) 55-59
Table 1 Total operation cost for the period 1995-2000: secondary and tertiary treatment cost
1995 C£ Operation cost Less Government contribution Tertiary treatment Depreciation Total cost including depreciation Annual flow
1996 C£
1997 C£
1998 C£
1999 C£
2000 C£
210,805 (62,000) 148,805
663,338 (121,000) 542,338
760,437 (123,000) 637,437
700,455 (116,000) 584,455
789,315 (128,000) 661,315
961,200 (135,000) 826,200
1,539,114 1,687,919
2,027,531 2,569,869
1,978,442 2,615,879
2,013,482 2,597,937
1,991,496 2,652,811
2,031,000 2,857,200
500,000
2,452,000
2,984,000
3,024,000
3,139,000
3,146,000
Cost per m 3, cent/m 3 Including depreciation Excluding depreciation
337.6 30.0
104.8 18.4
87.7 21.3
85.9 19.3
87.3 21.1
90.8 26.3
Year 1995 was the first year of operation and operation costs relate only for 5.5 months
Table 2 Total tertiary operation cost for the period 1995-2000
1995 C£
Operation cost Depreciation Annual flow Cost per year, cent/m 3
1996 C£
1997 C£
1998 C£
1999 C£
2000 C£
62,000 121,000 123,000 116,000 128,000 135,000 138,000 138,000 1 3 8 , 0 0 0 138,000 138,000 138,000 200,000 259,000 261,000 254,000 266,000 273,000 500,000 2,452,000 2,984,000 3,024,000 3,139,000 3,146,000 40.0 10.5 8.7 8.3 8.5 8.7
5. Advantages and benefits of wastewater reuse in Cyprus
The cost of production for the tertiary treated effluent is much lower than the desalinated water. It is estimated that the marginal cost of the tertiary treatment effluent is currently about 9 cent/mL O f course the average cost of the secondary treated effluent is not taken into account for comparison purposes, because it is considered that secondary treatment process is unavoidable for environmental and other hygienic reasons. Secondary trealment
of municipal and industrial wastewater is a must and should be there in any case. ° With the wastewater reuse the water resources are used more efficiently and more cost effectively. The treated effluent is used mainly for the less demanding uses o f agriculture and therefore fresh water of the best quality can be saved for domestic use. • Huge savings are achieved in the water resources because traditionally wastewater usually is disposed directly to the sea. • In parallel to the above, it offers the most environmental friendly water source, because,
I. Papaiacovou / Desalination 138 (2001) 55-59
if used properly it resolves environmental problems caused by untreated wastewater on the one hand and on the other it reduces the constant and continuing depletion of ground water. 6. Conclusions
The general conclusion is that the solution of the problem of water shortage cannot be achieved in the most efficient way, through the continuous use of natural water from dams or groundwater or desalinated water. The treated effluent offers a tremendous opportunity not only to contribute to the solution of the problem but also to the upgrading and protection of our environment, nowadays facing fatal threats.
59
The construction and operation of central sewerage systems not only in the large towns in Cyprus, but also in all the communities should be the first priority of the decision makers, merely because of its dual effect, i.e. firstly that of environmental protection and upgrading and secondly that of the potential of more efficient utilisation of the national water resources. Of course demand for water cannot be satisfied entirely by treated wastewater. In order to satisfy the water demand in Cyprus desalination is unavoidable. So, if a combination of natural fresh water, treated effluent and desalinated water is used, then a most efficient and cost effective use of the natural resources will be achieved with the average cost of water in the national economy substantially reduced.