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Sewage treatment and disposal strategies in Greece
Volume 23/1991/EMECS '90
Sewage Treatment and Disposal Strategies in Greece J. A . L E O N T A R I T I S
Min. of Env., Phys. Planning and Public Works, Athens, 10178, Greece
G r e e c e lies on the NE part of the M e d i t e r r a n e a n Sea, a closed sea w i t h a v e r y low rate of r e n o v a t i o n of its waters. The length and the shape of its coasts, the g e o g r a p h i c d i s t r i b u t i o n of the p o p u l a t i o n and the e c o n o m i c activities, as well as the relief of its terrain, have created many problems relating to the p o l l u t i o n of the coasts and the sea.
Factors
f a v o r i n g coastal
and sea p o l l u t i o n
in G r e e c e
We can d i s t i n g u i s h two c a t e g o r i e s of f a c t o r s w h i c h f a v o r coast and sea p o l l u t i o n . T h e f i r s t c a t e g o r y i n c l u d e s t h o s e w h i c h are i n d e p e n d e n t of h u m a n i n t e r f e r e n c e and the s e c o n d one t h o s e that d e p e n d on h u m a n a c t i v i t i e s . The f i r s t c a t e g o r y i n c l u d e s p h y s i c a l f a c t o r s , s u c h as the v e r y low r a t e of w a t e r r e n o v a t i o n of the M e d i t e r r a n e a n sea, the b i g l e n g t h of the c o a s t s in G r e e c e ( m o r e than 15000 km, including the islands ), the shape of the coastline ( m a n y s m a l l g u l f s ), the r e l i e f of the t e r r a i n (many n a r r o w p l a i n s lying c l o s e to the s e a ), the small l e n g t h and low v o l u m e of the w a t e r of the r i v e r s and the g e o g r a p h i c a l l o c a t i o n w h i c h o b l i g e s it to be the last c o u n t r y that is f l o w i n g t h r o u g h rivers coming from northern countries. The second category includes factors related to human activities. T h e e x i s t e n c e of t h e s e a c t i v i t i e s especially in r e g i o n s c l o s e to the c o a s t s ( urban, i n d u s t r i a l , t o u r i s t i c a r e a s etc ), as w e l l as the fact that m a n y g u l f s are the r e c i p i e n t s of polluted water resources ( pollution due to municipal, agricultural or industrial activities ) have created the n e c e s s i t y of i m m e d i a t e l y i n t r o d u c i n g e n v i r o n m e n t a l m a n a g e m e n t in the c o u n t r y .
Existing situation The major pollution problems exist in c l o s e d gulfs, in w h i c h m a n y a c t i v i t i e s h a v e b e e n g a t h e r e d . C h a r a c t e r i s t i c e x a m p l e s are: S a r o n i c o s gulf, w h i c h is the r e c i p i e n t of the s e w a g e of A t h e n s greater area, with a population of m o r e t h a n 4,0 m i l . i n h . , T h e r m a i k o s gulf, w h i c h is the r e c i p i e n t of S a l o n i k a g r e a t e r a r e a (pop. 1,0 mil.inh.), Pagassitikos gulf, in which not o n l y m u n i c i p a l s e w a g e but a l s o a g r i c u l t u r a l p o l l u t a n t s c o m i n g f r o m a b i g p l a i n are d i s c h a r g e d , A m v r a k i k o s gulf, a s h a l l o w and c l o s e d gulf w h i c h is the r e c i p i e n t of two i m p o r t a n t r i v e r s , N. and S. Evoikos gulfs, with many municipal and industrial activities etc. The s i t u a t i o n is d i f f e r e n t in e a c h case and d e p e n d s on the t o t a l p o l l u t i o n load and the s p e c i f i c f e a t u r e s of e a c h gulf. It is obvious that the degree of the pollution has immediate i n f l u e n c e on the d e v e l o p m e n t of the r e g i o n . Marine Pollution Bulletin, Vol. 23, pp. 691-693,1991. Printed in Great Britain 0025-326X/91 $3.00+0.00 O 1991 Pergamon Press plc
691
Marine Pollution Bulletin
Strategy
for facing the problem
The target is to f i n d the o p t i m u m s o l u t i o n , in o r d e r to the development of the r e g i o n s be c o n t i n u e d and the e n v i r o n m e n t not o n l y not be d e t e r i o r a t e d but be i m p r o v e d . F o r t h e s e r e a s o n s , in the last f e w years, s p e c i a l s t u d i e s are c a r r i e d out, in which, f o r e a c h region, p r o b l e m s are l i s t e d and s o l u t i o n s are p r o p o s e d . T h e s e s t u d i e s f o r m the g e n e r a l p l a n n i n g and the b a s i s for f u t u r e interference. The general layout of t h e s e s t u d i e s i n c l u d e s the f o l l o w i n g d a t a and p r o c e d u r e a) D e s c r i p t i o n of the p h y s i c a l e n v i r o n m e n t . In this u n i t y g e o l o g i c a l , h y d r o g e o l o g i c a l and c l i m a t o l o g i c a l data, as w e l l as d a t a for the s u r f a c e w a t e r s and the g r o u n d water, the coasts, the sea, the flora and the f a u n a are included. b) S t r u c t u r e of local economy, w h e r e the e x i s t i n g s i t u a t i o n is described and e s t i m a t i o n for the f u t u r e is made, for the different s e c t o r s of the economy, w i t h s p e c i f i c e m p h a s i s to the factors governing in the region (i.e. industry, t o u r i s t i c d e v e l o p m e n t , r e s o r t areas etc.). c) E x i s t i n g s i t u a t i o n of the w a t e r s u p p l y and s e w e r a g e systems. d) E s t i m a t i o n of the p o p u l a t i o n , w h e r e an a n a l y s i s of the t r e n d s for the p o p u l a t i o n is g i v e n ( permanent and n o n - p e r m a n e n t population ), t a k i n g into a c c o u n t its c o n n e c t i o n w i t h the e s t i m a t i o n s of u r b a n designs. e) D e s c r i p t i o n of the p o l l u t i o n s o u r c e s and e s t i m a t i o n of t h e i r loads, examination of the p o s s i b l e recipients, t a k i n g into account the existing legislation and the assimilative c a p a c i t y of the r e c i p i e n t s ( rivers, sea, u n d e r g r o u n d etc.). E x a m i n a t i o n of the p o s s i b i l i t y of r e u s i n g the sewage, as well as c o m b i n a t i o n s of m o r e t h a n one s o l u t i o n s . f) B a s e d on the a b o v e m e n t i o n e d data, a p r e l i m i n a r y d i m e n s i o n i n g of the c o l l e c t i o n , t r a n s p o r t , t r e a t m e n t and d i s p o s a l w o r k s is made. Treatment and d i s p o s a l of s l u d g e are a l s o included. The criteria for the selection of the treatment method i n c l u d e the e x i s t e n c e of s e a s o n a l and w e e k l y v a r i a t i o n s of the flows and the loads, the estimated increase of the population, p o s s i b l e t r e a t m e n t of septage, the s i m p l i c i t y of the works, the a v a i l a b i l i t y of p e r s o n n e l etc. g) T h e impact of the d i s p o s a l of the s e w a g e in the sea is carefully examined. The study is based on o c e a n o g r a p h i c studies, w h i c h i n c l u d e the l i s t i n g of d i f f e r e n t p a r a m e t e r s of the sea e n v i r o n m e n t during the s e a s o n s of the year. T h e s e parameters include physical characteristics (temperature, salinity, d e n s i t y , DO, Ph ), n u t r i e n t s , biological elements (plankton, benthos ), geologic data, data for currents, winds, waves, tides, h e a v y m e t a l s etc. B a s e d on t h e s e d a t a an estimation of the w a t e r q u a l i t y is made. T h e r e l e v a n t s t u d y is c a r r i e d out u s i n g e i t h e r m a t h e m a t i c a l m o d e l s or s i m p l e r methods, depending on the s p e c i a l characteristics of e a c h case. F o r the a l t e r n a t i v e s o l u t i o n s the impact of p o l l u t i o n to the r e c i p i e n t is e s t i m a t e d by d e t e r m i n i n g the c r i t i c a l p a r a m e t e r s as oxygen, phytoplankton, transparency, nutrients etc. The r e m o v a l of v i r u s e s and c o l i f o r m s is also e x a m i n e d .
692
Volume 23/1991/EMECS '90
Examp les Saronikos
gulf
:primary treatment + submarine outfall. Future e x t e n s i o n to b i o l o g i c a l t r e a t m e n t . A m v r a k i k o s gulf : s e c o n d a r y t r e a t m e n t + sea o u t f a l l and t e r t i a r y treatment for inland areas discharging in rivers. S. E v o i k o s gulf : s e c o n d a r y t r e a t m e n t + sea o u t f a l l . Pagassitikos gulf:primary treatment + submarine outfall (future e x t e n s i o n to b i o l o g i c a l t r e a t m e n t ) . T h e r m a i k o s gulf :secondary treatment.
Costs T h e c o n s t r u c t i o n cost of t r e a t m e n t and d i s p o s a l w o r k s the d e g r e e of the t r e a t m e n t , the p o p u l a t i o n s e r v e d , c o n d i t i o n s etc. S o m e t y p i c a l f i g u r e s are g i v e n below: F o r equ. p o p u l a t i o n 5 0 . 0 0 0 inh.: US $ 25 - 40 / inh. F o r equ. p o p u l a t i o n i 0 . 0 0 0 inh.: US $ 50 - 70 / inh. F o r equ. p o p u l a t i o n 2 . 0 0 0 inh.: US $ 75 - 1 2 5 / inh.
d e p e n d s on the local
Conclusions These studies without giving any d e t a i l s on the c o l l e c t i o n , t r e a t m e n t and d i s p o s a l of liquid w a s t e s , are c o n s i d e r e d to be a g o o d tool for a f u r t h e r g e n e r a l policy, because they provide cost data, t h e y list the e x i s t i n g s i t u a t i o n of the r e c i p i e n t s and t h e y g i v e f u t u r e e s t i m a t i o n f o r m a n y a l t e r n a t i v e s c h e m e s of t r e a t m e n t and d i s p o s a l . In t h i s w a y t h e y c o n s t i t u t e a v e r y g o o d tool to the d e c i s i o n m a k e r s , in o r d e r to p r o g r a m the c o n s t r u c t i o n of the w o r k s and to propose measures, after comparative evaluation in different r e g i o n s of the c o u n t r y .
693
Sewage Treatment and Disposal Strategies in Greece J. A . L E O N T A R I T I S
Min. of Env., Phys. Planning and Public Works, Athens, 10178, Greece
G r e e c e lies on the NE part of the M e d i t e r r a n e a n Sea, a closed sea w i t h a v e r y low rate of r e n o v a t i o n of its waters. The length and the shape of its coasts, the g e o g r a p h i c d i s t r i b u t i o n of the p o p u l a t i o n and the e c o n o m i c activities, as well as the relief of its terrain, have created many problems relating to the p o l l u t i o n of the coasts and the sea.
Factors
f a v o r i n g coastal
and sea p o l l u t i o n
in G r e e c e
We can d i s t i n g u i s h two c a t e g o r i e s of f a c t o r s w h i c h f a v o r coast and sea p o l l u t i o n . T h e f i r s t c a t e g o r y i n c l u d e s t h o s e w h i c h are i n d e p e n d e n t of h u m a n i n t e r f e r e n c e and the s e c o n d one t h o s e that d e p e n d on h u m a n a c t i v i t i e s . The f i r s t c a t e g o r y i n c l u d e s p h y s i c a l f a c t o r s , s u c h as the v e r y low r a t e of w a t e r r e n o v a t i o n of the M e d i t e r r a n e a n sea, the b i g l e n g t h of the c o a s t s in G r e e c e ( m o r e than 15000 km, including the islands ), the shape of the coastline ( m a n y s m a l l g u l f s ), the r e l i e f of the t e r r a i n (many n a r r o w p l a i n s lying c l o s e to the s e a ), the small l e n g t h and low v o l u m e of the w a t e r of the r i v e r s and the g e o g r a p h i c a l l o c a t i o n w h i c h o b l i g e s it to be the last c o u n t r y that is f l o w i n g t h r o u g h rivers coming from northern countries. The second category includes factors related to human activities. T h e e x i s t e n c e of t h e s e a c t i v i t i e s especially in r e g i o n s c l o s e to the c o a s t s ( urban, i n d u s t r i a l , t o u r i s t i c a r e a s etc ), as w e l l as the fact that m a n y g u l f s are the r e c i p i e n t s of polluted water resources ( pollution due to municipal, agricultural or industrial activities ) have created the n e c e s s i t y of i m m e d i a t e l y i n t r o d u c i n g e n v i r o n m e n t a l m a n a g e m e n t in the c o u n t r y .
Existing situation The major pollution problems exist in c l o s e d gulfs, in w h i c h m a n y a c t i v i t i e s h a v e b e e n g a t h e r e d . C h a r a c t e r i s t i c e x a m p l e s are: S a r o n i c o s gulf, w h i c h is the r e c i p i e n t of the s e w a g e of A t h e n s greater area, with a population of m o r e t h a n 4,0 m i l . i n h . , T h e r m a i k o s gulf, w h i c h is the r e c i p i e n t of S a l o n i k a g r e a t e r a r e a (pop. 1,0 mil.inh.), Pagassitikos gulf, in which not o n l y m u n i c i p a l s e w a g e but a l s o a g r i c u l t u r a l p o l l u t a n t s c o m i n g f r o m a b i g p l a i n are d i s c h a r g e d , A m v r a k i k o s gulf, a s h a l l o w and c l o s e d gulf w h i c h is the r e c i p i e n t of two i m p o r t a n t r i v e r s , N. and S. Evoikos gulfs, with many municipal and industrial activities etc. The s i t u a t i o n is d i f f e r e n t in e a c h case and d e p e n d s on the t o t a l p o l l u t i o n load and the s p e c i f i c f e a t u r e s of e a c h gulf. It is obvious that the degree of the pollution has immediate i n f l u e n c e on the d e v e l o p m e n t of the r e g i o n . Marine Pollution Bulletin, Vol. 23, pp. 691-693,1991. Printed in Great Britain 0025-326X/91 $3.00+0.00 O 1991 Pergamon Press plc
691
Marine Pollution Bulletin
Strategy
for facing the problem
The target is to f i n d the o p t i m u m s o l u t i o n , in o r d e r to the development of the r e g i o n s be c o n t i n u e d and the e n v i r o n m e n t not o n l y not be d e t e r i o r a t e d but be i m p r o v e d . F o r t h e s e r e a s o n s , in the last f e w years, s p e c i a l s t u d i e s are c a r r i e d out, in which, f o r e a c h region, p r o b l e m s are l i s t e d and s o l u t i o n s are p r o p o s e d . T h e s e s t u d i e s f o r m the g e n e r a l p l a n n i n g and the b a s i s for f u t u r e interference. The general layout of t h e s e s t u d i e s i n c l u d e s the f o l l o w i n g d a t a and p r o c e d u r e a) D e s c r i p t i o n of the p h y s i c a l e n v i r o n m e n t . In this u n i t y g e o l o g i c a l , h y d r o g e o l o g i c a l and c l i m a t o l o g i c a l data, as w e l l as d a t a for the s u r f a c e w a t e r s and the g r o u n d water, the coasts, the sea, the flora and the f a u n a are included. b) S t r u c t u r e of local economy, w h e r e the e x i s t i n g s i t u a t i o n is described and e s t i m a t i o n for the f u t u r e is made, for the different s e c t o r s of the economy, w i t h s p e c i f i c e m p h a s i s to the factors governing in the region (i.e. industry, t o u r i s t i c d e v e l o p m e n t , r e s o r t areas etc.). c) E x i s t i n g s i t u a t i o n of the w a t e r s u p p l y and s e w e r a g e systems. d) E s t i m a t i o n of the p o p u l a t i o n , w h e r e an a n a l y s i s of the t r e n d s for the p o p u l a t i o n is g i v e n ( permanent and n o n - p e r m a n e n t population ), t a k i n g into a c c o u n t its c o n n e c t i o n w i t h the e s t i m a t i o n s of u r b a n designs. e) D e s c r i p t i o n of the p o l l u t i o n s o u r c e s and e s t i m a t i o n of t h e i r loads, examination of the p o s s i b l e recipients, t a k i n g into account the existing legislation and the assimilative c a p a c i t y of the r e c i p i e n t s ( rivers, sea, u n d e r g r o u n d etc.). E x a m i n a t i o n of the p o s s i b i l i t y of r e u s i n g the sewage, as well as c o m b i n a t i o n s of m o r e t h a n one s o l u t i o n s . f) B a s e d on the a b o v e m e n t i o n e d data, a p r e l i m i n a r y d i m e n s i o n i n g of the c o l l e c t i o n , t r a n s p o r t , t r e a t m e n t and d i s p o s a l w o r k s is made. Treatment and d i s p o s a l of s l u d g e are a l s o included. The criteria for the selection of the treatment method i n c l u d e the e x i s t e n c e of s e a s o n a l and w e e k l y v a r i a t i o n s of the flows and the loads, the estimated increase of the population, p o s s i b l e t r e a t m e n t of septage, the s i m p l i c i t y of the works, the a v a i l a b i l i t y of p e r s o n n e l etc. g) T h e impact of the d i s p o s a l of the s e w a g e in the sea is carefully examined. The study is based on o c e a n o g r a p h i c studies, w h i c h i n c l u d e the l i s t i n g of d i f f e r e n t p a r a m e t e r s of the sea e n v i r o n m e n t during the s e a s o n s of the year. T h e s e parameters include physical characteristics (temperature, salinity, d e n s i t y , DO, Ph ), n u t r i e n t s , biological elements (plankton, benthos ), geologic data, data for currents, winds, waves, tides, h e a v y m e t a l s etc. B a s e d on t h e s e d a t a an estimation of the w a t e r q u a l i t y is made. T h e r e l e v a n t s t u d y is c a r r i e d out u s i n g e i t h e r m a t h e m a t i c a l m o d e l s or s i m p l e r methods, depending on the s p e c i a l characteristics of e a c h case. F o r the a l t e r n a t i v e s o l u t i o n s the impact of p o l l u t i o n to the r e c i p i e n t is e s t i m a t e d by d e t e r m i n i n g the c r i t i c a l p a r a m e t e r s as oxygen, phytoplankton, transparency, nutrients etc. The r e m o v a l of v i r u s e s and c o l i f o r m s is also e x a m i n e d .
692
Volume 23/1991/EMECS '90
Examp les Saronikos
gulf
:primary treatment + submarine outfall. Future e x t e n s i o n to b i o l o g i c a l t r e a t m e n t . A m v r a k i k o s gulf : s e c o n d a r y t r e a t m e n t + sea o u t f a l l and t e r t i a r y treatment for inland areas discharging in rivers. S. E v o i k o s gulf : s e c o n d a r y t r e a t m e n t + sea o u t f a l l . Pagassitikos gulf:primary treatment + submarine outfall (future e x t e n s i o n to b i o l o g i c a l t r e a t m e n t ) . T h e r m a i k o s gulf :secondary treatment.
Costs T h e c o n s t r u c t i o n cost of t r e a t m e n t and d i s p o s a l w o r k s the d e g r e e of the t r e a t m e n t , the p o p u l a t i o n s e r v e d , c o n d i t i o n s etc. S o m e t y p i c a l f i g u r e s are g i v e n below: F o r equ. p o p u l a t i o n 5 0 . 0 0 0 inh.: US $ 25 - 40 / inh. F o r equ. p o p u l a t i o n i 0 . 0 0 0 inh.: US $ 50 - 70 / inh. F o r equ. p o p u l a t i o n 2 . 0 0 0 inh.: US $ 75 - 1 2 5 / inh.
d e p e n d s on the local
Conclusions These studies without giving any d e t a i l s on the c o l l e c t i o n , t r e a t m e n t and d i s p o s a l of liquid w a s t e s , are c o n s i d e r e d to be a g o o d tool for a f u r t h e r g e n e r a l policy, because they provide cost data, t h e y list the e x i s t i n g s i t u a t i o n of the r e c i p i e n t s and t h e y g i v e f u t u r e e s t i m a t i o n f o r m a n y a l t e r n a t i v e s c h e m e s of t r e a t m e n t and d i s p o s a l . In t h i s w a y t h e y c o n s t i t u t e a v e r y g o o d tool to the d e c i s i o n m a k e r s , in o r d e r to p r o g r a m the c o n s t r u c t i o n of the w o r k s and to propose measures, after comparative evaluation in different r e g i o n s of the c o u n t r y .
693