c
.
APPLICATIONS O F ELECTROSTATIC PROCESSES FOR THE CONTROL OF
SCALE, CORROSION AND BIOLOGICS I N COOLING TOWERS
Robert S. Reimers, Ph.D.
Department of Environmental H e a l t h S c i e n c e s *
School of P u b l i c H e a l t h and T r o p i c a l Medicine
Tulane U n i v e r s i t y
New O r l e a n s LA 70112
P a u l S. JeKernion
C. Paul Lo
EIRA, I n c .
P. 0. Box 6978
Metairie LA 70009
Roy C . McMahon
E l e c t o s t a t i c s Equipment C o r p o r a t i o n
1665 J a r b o e
Kansas C i t y MO 64108
Linda S o u t h e r l a n d *
Ann C. Anderson, Ph.D*
I)
ABSTRACT
The a p p l i c a t i o n of e l e c t r o s t a t i c p r o c e s s e s f o r t h e c o n t r o l of s c a l e , c o r r o s i o n ,
and b i o l o g i c s i n c o o l i n g towers w i l l b e d i s c u s s e d . F a c t o r s i n f l u e n c i n g t h e
e l e c t r o s t a t i c s p r o c e s s will be e l u c i d a t e d i n t h e s e areas: 1 ) p r o c e s s l i m i t a t i o n s ;
2 ) o p e r a t i o n s arid maintenance problems; and 3) p r o c e s s r e l i a b i l i t y .
In fact,
i n many a r e a s , i t a p p e a r s t h a t complete t r e a t m e n t u t i l i z i n g t h e e l e c t r o s t a t i c s
p r o c e s s r e q u i r e s chemical a d d i t i v e s .
INTRODUCTION
The o b j e c t i v e s of t h i s paper a r e f o u r f o l d : 1) t o d i s c u s s t h e mechanisms by which
e l e c t r o s t a t i c s processes treat i n d u s t r i a l waters; 2) t o relate recent operational
arid maintenance p r o b l e m s ; 3) t o c a p s u l a t e p a r t i c u l a r l i m i t a t i o n s of e l e c t r o s t a t i c
p r o c e s s e s ; and 4) t o n o t e t h e p r o c e s s r e l i a b i l i t y .
8
These "gadget" p r o c e s s e s have o f f e r e d a n a p p a r e n t "something-for-nothing" o r a
k i n d o f panacea p r o c e s s t o waste and w a t e r t r e a t m e n t . Such g a d g e t s a r e a l s o
claimed t o b e s p e c i a l d e v i c e s r e q u i r i n g n o t e c h n i c a l c o n t r o l which w i l l t r e a t
water by non-chemical means t o p r e v e n t s c a l e , c o r r o s i o n and t o r e s o l v e o t h e r
problems e n c o u n t e r e d i n t h e i n d u s t r i a l u s e of w a t e r . S k e p t i c i s m i s due p r i m a r i l y
t o t h e l a c k of s c i e n t i f i c s u b s t a n t i a t i o n of t h e mechanisms. I n most s i t u a t i o n s ,
the above s k e p t i c i s m s h o u l d b e of major c o n c e r n , b u t r e c e n t r e s e a r c h h a s b r o u g h t
t o t h e f o r e f r o n t d a t a t h a t I n d i c a t e s t h a t a p p l i c a t i o n of i n d u c e d - f i e l d p r o c e s s e s
may be a v i a b l e p r o c e s s f o r water treatment u n d e r s p e c i f i c e n v i r o n m e n t a l c o n d i t i o n s .
BACKGROUND
I n t h e mid-19th c e n t u r y t h e f i r s t water c o n d i t i o n i n g "gadget" p a t e n t i n t h e
United States was Issued. S i n c e t h a t time, over 100 s u c h p a t e n t s w e r e I s s u e d .
These p r o c e s s e s had no t e c h n i c a l c o n t r o l and r e q u i r e d no c h e m i c a l a d d i t i o n t o
p r e v e n t s c a l e , c o r r o s i o n and o t h e r problems e n c o u n t e r e d in t h e u s e of water ( 1 ) .
I n t h e l a t e 1950's E 1 i a s s e n . g . g.,
(2) n o t e d no i n h i b i t i o n o f scale f o r m a t i o n
and no r e d u c t i o n i n t h e r a t e of c o r r o s i o n o v e r a f o u r month p e r i o d u s i n g
induced-field procces. This Ineffectiveness w a s speculated t o be a r e s u l t of
low f i e l d d e n s i t i e s .
I n 1977, a p u b l i c a t i o n q u e s t i o n e d t h e c l a i m s of t h e s e
p r o c e s s e s t o p r e v e n t s c a l e and i n h i b i t c o r r o s i o n . I t was b e l i e v e d t h a t t h e
i n d u c e d - f i e l d p r o c e s s e s ( m a g n e t i c , e l e c t r o m a g n e t i c and e l e c t r o s t a t i c ) were i n
c o n f l i c t w i t h t h e b a s i c p r i n c i p l e s of s c i e n c e and a l l o w e d f a r t o o l i t t l e e x p o s u r e
r e l i a b i l i t y of c a t i o n s t o
t o t h e induced f i e l d . n e a u t h o r questioned t h e
a d s o r b e l e c t r o n s and wofidered a b o u t t h e memory of t h i s t r e a t m e n t a f t e r p a s s i n g
t h r o u g h t h i s f i e l d ( 3 ) . R e c e n t l y , two p a p e r s warned i n d u s t r y of non-chemical
w a t e r t r e a t m e n t p r o c e s s e s (4.5). One p a p e r (4) emphasized t h e same p o i n t s ( i n
t h e e x a c t wording) as t h e p a p e r r e l e a s e d i n 1977 ( 3 ) . The o t h e r p a p e r (5)
reviewed t h e l i t e r a t u r e concerned w i t h t h e problems r e s u l t i n g from t h e p r o c e s s e s
and examined c l a i m s n a d e by v a r i o u s i n d u c e d f i e l d and u l t r a s o n i c water c o n d i t i o n i n g
processes.
T h e s k e p t l c i s m s u r r o u n d i n g t h e s e p r o c e s s e s i s due t o t h e l a c k of s c i e n t i f i c
s u b s t a n t i a t i o n of t h e d e s c a l i n g o r d i s i n f e c t i o n . Recent r e s e a r c h f i n d i n g s ,
however, i n d i c a t e t h e a p p l i c a t i o n of e l e c t r o s t a t i c s and u l t r a s o n i c s a s a v i a b l e
p r o c e s s t o water t r e a t m e n t . I n t h e l a s t 15 y e a r s , r e s e a r c h h a s r e i n f o r c e d
t h e b e n e f i c i a l e f f e c t s of m a g n e t i c and e l e c t r o s t a t i c f i e l d s i n t h e r e d u c t i o n
of b o i l e r s c a l e ( 6 , 7 ) . Toshi and Kamat (6) n o t e d a d e c r e a s e i n t h e pH of
d i s t i l l e d water (0.62 pH u n i t s ) exposed t o m a g n e t i c f i e l d s i n t h e r a n g e o f
1900-5700 g a u s s . S i m i l a r o b s e r v a t i o n s have been r e p o r t e d f o r n a t u r a l l y
o c c u r r i n g w a t e r s . Measurements of t h e p h y s i c a l p r o p e r t i e s o f water showed v e r y
l i t t l e change, w i t h t h e e x c e p t i o n of pH, a f t e r p a s s i n g t h r o u g h a m a g n e t i c f i e l d .
A v a r i e t y of e x p l a n a t i o n s h a s been p r o p o s e d for t h i s phenomenon; one s u c h
i n v o l v i n g a m a g n e t i c a l l y i n d u c e d change i n t h e pH o f t h e w a t e r (8). The r e d u c t i o n
i n pH i n d i c a t e s a n i n c r e a s e i n Lewis a c i d s ( e l e c t r o n a c c e p t o r ) due t o t h e r e l e a s e
of a c i d i c s c a l e complexes. Quickendon, et. &., was n o t a b l e t o s u b s t a n t i a t e
t h e pH d r o p , b u t o b s c r v e d pH r i s e w i t h d i s t i l l e d water, p o s s i b l y due t o t h e
formation of L e w i s b a s e s ( e l e c t r o n donor
) i n c o n t a i n e r s which had n o
s c a l e t o absorb e l e c t o n s .
Kobikus (10) found m a g n e t i c f i e l d water t r e a t m e n t p r o c e s s e s r e d u c e d s c a l e ,
b u t t h e s e same p r o c e s s e s had no c o n t r o l o v e r c o r r o s i o n . I n a d d i t i o n , t h e
i n f l u e n c e of a m a g n e t i c f i e l d tended t o change t h e c r y s t a l l i n e s t r u c t u r e of
c a l c i u m c a r b o n a t e s c a l e from c a l c i t e t o a r g o n i t e . J a p a n e s e r e s e a r c h e r s (11)
reported similar results. I n addition, they noted corrosion i n h i b i t i o n with
t h e i n d u c e d - f i e l d p r o c e s s e s i n b o i l i n g water t r e a t m e n t . As a r e s u l t of t h e s e
s t u d i e s , U n i v e r s i t y o f Michigan r e s e a r c h e r s ( 1 2 ) i n v e s t i g a t e d t h e e f f e c t i v e n e s s
o f e l e c t r o s t a t i c and m a g n e t i c t r e a t m e n t o f water t o p r e v e n t s c a l i n g , t o
i n h i b i t c o r r o s i o n , arid t o reduce bioltgica: a c i i v i t y . V i t h d e c t r a m g n e t i c a l l y
treated water, t h e y found lower c o r r o s i o n of aluminum and less scale f o r m a t i o n
a t 180°F o v e r 48 h o u r s t h a n i n u n t r e a t e d water. Daphnia were found t o b e
somewhat less v i a b l e i n t h e p r e s e n c e of e l e c t r o m a g n e t i c a l l y t r e a t e d water;
however, t h e r e is some q u e s t i o n c o n c e r n i n g t h e s e results. E l e c t r o s t a t i c
t r e a t m e n t of water produced s o f t scale f o r m a t i o n , w h i l e n o n - t r e a t e d water p r o d u c e s
a tenacious scale a t 2000C.
Recent s t u d i e s on i n d u c e d - f i e l d t r e a t m e n t i n i n d u s t r i a l s e t t i n g s h a v e p r o d u c e d
Work a t Clemson by Duffy (13) showed t h a t e l e c t r o m a g n e t i c t r e a t m e n t was o n l y e f f e c t i v e when f e r r i c h y d r o x i d e was p r e s e n t . F e r r i c
h y d r o x i d e i n t h e f e e d water d e c r e a s e d t h e f o r m a t i o n of scale and t h e c o n t r o l of
s c a l e v a r i e d d i r e c t l y w i t h concentration o f f e r r i c h y d r o x i d e and c o n v e r s e l y
w i t h t e m p e r a t u r e ; b u t S c d e was i n h i b i t e d a t pH levels r a n g i n g from 6 t o 11.
more i n t e r e s t i n g phenomena.
- 2-
I n 1979, K r a j i i c and M i l s e v i c - K r a j i i c (14) p u b l i s h e d case h i s t o r i e s o f
f a c i l i t i e s u s i n g e l e c t r o m a g n e t i c water t r e a t m e n t d e v i c e s . They n o t e d t h a t
s c a l e d b o i l e r s s t a r t e d d e s c a l i n g w i t h i n a month of i n s t a l l a t i o n o f such u n i t s .
D e s c a l i n g was n o t e d i n s i t u a t i o n s where c a l c i u m s u l f a t e , magnesium c a r b o n a t e ,
c a l c i u m c a r b o n a t e , c a l c i u m h y d r o x i d e , magnesium h y d r o x i d e and c a l c i u m magnesium
c a r b o n a t e were s u p e r s a t u r a t e d a f t e r c o n s i d e r a t i o n o f t e m p e r a t u r e and i o n i c
s t r e n g t h . S i m i l a r r e s u l t s were o b s e r v e d f o r c o o l i n g t o w e r s and a l a b o r a t o r y
water d i s t i l l e r .
The a b i l i t i e s o f u l t r a s o n i c s , e l e c t r o s t a t i c s , e l e c t r o m a g n e t i c r a d i a t i o n and
m a g n e t i c r a d i a t i o n on m i c r o b i c r e d u c t i o n have been i n v e s t i g a t e d d u r i n g t h e
p a s t f i f t y y e a r s . The f e a s i b i l i t y o f t h e s e methods depends g e n e r a l l y on t h e
i n t e n s i t y of power r e q u i r e d t o d i s i n f e c t or i n a c t i v a t e ( 1 5 ) .
Recent s t u d i e s
have shown p o t e n t i a l p a t h o g e n i n a c t i v a t i o n a t l o w e r i n t e n s i t y o f r a d i a t i o n or
u l t r a s o n i c s when c o u p l e d w i t h c h e m i c a l a g e n t s , ozone o r s o l u b l e o r g a n i c s (15,lC’.
With t h e r e c e n t q u e s t i o n s c o n c e r n i n g t h e e n v i r o n m e n t a l impact o f c h l o r i n a t i o n
on human h e a l t h , t h e s y n e r g i s t i c a p p l i c a t i o n s of u l t r a s o n i c s a n d / o r e l e c t r o s t a t i c s
w i t h c h e m i c a l a d d i t i v e s a p p e a r s t o b e a v e r y f e a s i b l e approach t o e f f e c t i v e
pathogen i n a c t i v a t i o n a t low c o s t s and r e d u c e d impact t o p u b l i c h e a l t h .
M i c r o b i a l k i l l w i t h u l t r a s o n i c a t i o n was f i r s t r e p o r t e d i n 1929 ( 1 7 ) .
Recent
i n v e s t i g a t i o n s h o w s t h a t t h i s d i s i n f e c t i o n a p p e a r s t o b e a f u n c t i o n of i n t e n s i t y
r a t h e r t h a n f r e q u e n c v . For example, E s h e r i c h i a c o l i B. a r e i n a c t i v a t e d
Similar
o n l y i f t h e i n t e n s i t y i s k e p t a t 2.25 watts/cmL or g r e a t e r ( 1 7 ) .
o b s e r v a t i o n s have been n o t e d by C r o a k l y , et. al. (18). All s a y t h a t u l t r a s o n i c a t i o n
w i l l k i l l m i c r o b e s , l u t n o t 100% k i l l . T h e r e z r e , t h e problem of r e g r o w t h
can become a major c o n c e r n . (18,19)
U l t r a s o n i c a t i o n can b e used a s a d i s i n f e c t i o n p r o c e s s when c o u p l e d w i t h
h e a t i n g or c h e m i c a l s , a n d , i n f a c t , t h e s y n e r g i s t i c s of h e a t a n d / o r c h e m i c a l s
can make u l t r a s o n i c a t i o n e c o n o m i c a l l y f e a s i b l e (15, 20, 2 1 ) . Murray (22) and
et. a 1 . ( 2 3 ) r e p o r t e d t h a t u l t r a s o n i c a t i o n a l o n e d i d n o t have a
Ouellette, g e r m i c i d a l e f f e c t or i n c r e a s e r e a c t i v i t y , b u t when used w i t h o t h e r t r e a t m e n t
methods or c a t a l y s t s , t h e i n f l u e n c e of t h e u l t r a s o n i c s made t h e r e a c t i o n s o f
b i o k i l l m a g n i t u d i n a l l y more e f f e c t i v e (22.23).
Recent s t u d i e s a t T u l a n e n o t e d a f i v e - f o l d e x p o n e n t i a l r e d u c t i o n i n t o t a l
b a c t e r i a when a n ultrasonicfelectrostatic u n i t was c o n n e c t e d t o a commercial
b o t t l e washing machine.
The minimum t o t a l b a c t e r i a d e n s i t y w a s o b s e r v e d a t
a p p r o x i m a t e l y two d a y s o f t r e a t m e n t w i t h a d e f i n i t e r e g r o w t h o f b a c t e r i a o v e r
t h e n e x t two days. C o n c u r r e n t l y , p r e l i m i n a r y r e s e a r c h was c o n d u c t e d i n t h e f i e l d
u s i n g a s i m i l a r u n i t f o r s e c o n d a r y e f f l u e n t s . This p r o c e s s r e d u c e d c h l o r i n e
demand by 20% and reduced t o t a l c o l i f o r m by 70% as a f u n c t i o n of b o t h f l a w and
initial concentration ( I h ) .
DISCUSS I O N
The d i s c u s s i o n w i l l b e d i v i d e d i n t o two s e c t i o n s . The f i r s t s e c t i o n w i l l
be concerned w i t h t h e mechanisms by which e l e c t r o s t a t i c s p r o c e s s e s c o n t r o l
s c a l e , i n h i b i t c o r r o s i o n and i n a c t i v a t e p a t h o g e n s .
I n t h e second s e c t i o n , t h e
r e a l w o r l d problems c o n c e r n i n g o p e r a t i o n and m a i n t e n a n c e , p a r t i c u l a r l i m i t a t i o n s ,
and p r o c e s s r e l i a b i l i t y w i l l b e e l u c i d a t e d .
S p e c u l a t e d Mechanisms € o r D e s c a l i n g , B i o i n a c t i v a t i o n and A n t i c o r r o s i o n by
E l e c t r o s t a t i c Processes
Scale Inhibition
A major o b j e c t i v e of t h i s paper i s t o a t t e m p t an e x p l a n a t i o n of t h e mechanisms
by which e l e c t r o s t a t i c p r o c e s s e s d e s c a l e . I t is i m p o r t a n t t o n o t e t h a t t h i s
d e s c a l i n g a n d / o r s c a l e i n h i b i t i o n p r o c e s s is v e r y complex and i n v o l v e s
c o n c e p t s b e l o n g i n g t o c o l l o d i a l c h e m i s t r y , p h y s i c a l . c h e m i s t r y , o r g a n i c chemi s t r y , etc.
Recent s t u d i e s by R u s s i a n s and Americans00,11,16,27,28,29) n o t e d f o u r phenomena
t h a t i n f l u e n c e t h e d e s c a l i n g p r o c e s s : 1) t h e b u i l d - u p of s l u d g e i n t h e water
w h e r e i n d u c e d - f i e l d p r o c e s s e s are a p p l i e d ; 2) t h e i n c r e a s e d e f f i c i e n c y of i n d u c c d
f i e l d p r o c e s s e s w i t h t h e a d d i t i o n of s o l u b l e i r o n and magensium c o n c e n t r a t i o n s ;
3) t h e i m p o r t a n c e of w a t e r q a u l i t y i n t h e e f f e c t i v e n e s s of t h e e l e c t r o s t a t i c
p r o c e s s e s ; and 4) t h e i n f l u e n c e of z e t a p o t e n t i a l on t h e a p p l i c a t i o n of e l e c t r o s t a t i c p r o c e s s e s i n w a t e r t r e a t n e n t and s o l i d s s e p a r a t i o n . The i m p o r t a n c e of
t h e above f o u r phenomena had o f t e n been o v e r l o o k e d and r e s u l t e d i n t h e f a i l u r e
of many i n d u c e d - f i e l d p r o c e s s e s which c o u l d have been v e r y f e a s i b l e .
S l u d g e b u i l d - u p i n e l e c t r o s t a t i c p r o c e s s e s r e s u l t s from t h e o b s e r v e d i n c r e a s e s
i n n u c l e i formed i n t h e w a t e r i n s t e a d of on t h e s i d e s of p i p e s , c o o l i n g t o w e r s ,
b o i l e r s , e t c . The phenomenon had been r e p o r t e d by v a r i o u s r e s e a r c h e r s (25,25).
I t is n e c e s s a r y t o remove t h e s e s o l i d s e i t h e r by c l a r i f i c a t i o n o r f i l t r a t i o n .
I n c o o l i n g tower a p p l i c a t i o n s , f i l t r a t i o n i s a d v i s a b l e . A d d i t i o n s of i r o n and
magnesium i n c r e a s e t h e e f f i c i e n c y of magnetic o r e l e c t r o s t a t i c t r e a t m e n t . For
example, 0.8 mg/l of f e r r i c h y r d o x i d e i n c r e a s e d t h e e f f i c i e n c y of c o o l i n g tower
and deep w e l l i n j e c t i o n p r o c e s s e s by 50% ( 9 ) . A d d i t i o n of i r o n i n c r e a s e d
t r e a t m e n t e f f i c i e n c y i n t h e pH r a n g e s of 6-11 up t o 2 m g / l as i r o n . I n c r e a s e d
e f f i c i e n c y is due t o t h e a l t e r a t i o n of t h e s c a l e s t r u c t u r e of c a l c i u m c a r b o n a t e
and c a l c i u m s u l f a t e and t h e a d d i t i o n of p o t e n t i a l s e e d s i n t h e aqueous media
by t h e f e r r i c h y r d o x i d e complexes ( 3 ) .
The i n f l u e n c e of w a t e r q u a l i t y has been n o t e d by Reimers, e t . a l . and Biochenl-.o
and Sapogin (26) These r e s e a r c h e r s have noted t h e f o l l o w i n g :
C o n s t i t u e n t s t h a t Improved E l e c t r o s t a t i c T r e a t m e n t
Hardness
Alkalini ty
TDS ( T o t a l D i s s o l v e d S o l i d s )
Oxidant C o n s t i t u e n t s
Ca 1c ium
Bicarbonate
Nitrate
Magensium
C o n s t i t u e n t s t h a t I n h i b i t E l e c t r o s t a t i c Treatment
Suspended S o l i d s
Organics
Reduced N i t r o g e n Compounds ,
Silicates
Reduced C o n s t i t u e n t s
S u l f h y d r i l O r g a n i c Compounds
It rhould b e emphasized t h a t e l e c t r o s t a t i c treatment will only o c c u r when t h e
proper dissolved rolid ( soluble conrtituent) l e p r e s e n t . This has b e e n
n o t e d by v a r i o u s ot1it.r r e s e a r c h e r s ( 28.29).
I n a d d i t i o n , t h e e f f e c t of e l e c t r o s t a t i c f i e l d s i n t h e z e t a p o t e n t i a l h a s
been r e p o r t e d by Means and Mour ( 2 5 ) and B i o c h e n k o a n d S a p o g i n ( 2 6 ) . The
e l e c t r o s t a t i c f i e l d a l t e r s t h e o u t e r c h a r g e of a s o l u b l e c o n s t i t u e n t by
changing t h e h y d r o x i d e complex s t r u c t u r e . T h i s e x p l a n a t i o n h a s b e e n u s e d t o
s u b s t a n t i t a t e t h e e f f e c t i v e n e s s of e l e c t r o s t a t i c p r o c e s s e s f o r s o l i d s removed
i n v a r i o u s water and w a s t e t r e a t m e n t p r o c e s s e s . A r e c e n t R u s s i a n p u b l i c a t i o n
h a s r e p o r t e d t h e e f f e c t i v e n e s s of t h e lime s o f t e n i n g improved a f t e r p a s s i n g
through a magnetic f i e l d b e f o r e c l a r i f i c a t i o n ( 2 8 ) .
A s a r e s u l t of t h e above o b s e r v a t i o n s , i t i s s p e c u l a t e d t h a t t h e mechanisms b y
which e l e c t r o s t a t i c p r o c e s s e s d e s c a l e f o l l o w t h e c h e m i s t r y d e s c r i b e d i n P e a r s o n ' s
Hard and S o f t Acid-Base Theory ( 3 0 ) . I n f i e l d s i t u a t i o n s , d e s c a l i n g h a s been
o b s e r v e d o n l y when c o n c e n t r a t i o n s of calcium, magensium, i r o n and o t h e r P e a r s o n
Hard Acids are p r e s e n t . These chemical compounds a d s o r b an e l e c t r o n and b e c o r c
P e a r s o n H a r d Bases which t e n d t o r e a c t w i t h o x i d e t y p e P e a r s o n Hard A c i d s ,
s u c h as c a r b o n a t e , p h o s p h a t e , s u l f i t e , e t c . T a b l e 1 shows t h e c h a r a c t e r i s t i c s
of P e a r s o n Hard and S o f t Acids. An i m p o r t a n t p o i n t i s t h a t P e a r s o n Hard A c i d s
o n l y r e a c t w i t h P e a r s o n u a r d Bases and P e a r s o n S o f t A c i d s r e a c t o n l y w i t h
P e a r s o n S o f t Bases.
I n o u r s t u d i e s , t h e r o l e of t h e e l e c t r o s t a t i c f i e l d (low b e t a f i e l d ) i n w a t e r
t r e a t m e n t h a s been a s a c a t a l y s t which i n d u c e s c h e m i c a l r e a c t i o n s . When
o r g a n i c s ( a s shown i n T a b l e 2 ) which t e n d t o form f r e e r a d i c a l s were exposed
t o a n e l e c t r o s t a t i c f i e l d , e x o t h e r m i c r e a c t i o n s o c c u r r e d o n l v when t h e e l e c t r o d e
had a c a p a c i t a n c e of 7000 v o l t s (no h e a t r e l e a s e a t 3500 v o l t s ) . I t h a s been
s p e c u l a t e d t h a t a s i m i l a r phenomena o c c u r s i n t h e i n o r g a n i c r e a c t i o n s and t h a t
t h e i n f l u e n c e of i n c r e a s i n g t h e c a p a c i t a n c e on t h e e l e c t r o d e i n c r e a s e s t h e
s t a b i l i t y of c a l c i u m c a r b o n a t e two f o l d from f i v e times i t s s o l u b i l i t y t o
t e n times i t s o l u b j l i t y . A s c h e m a t i c of t h i s mechanism i s shown below:
+
Ca 2
+
+ ~ C ~ C= OCa~ +2 + 2 ~ a +2
2CO3 - 2
2
2.
In addition,
FeS3
+ e- e - f i+e l d
e-field
+ e- -
Fe +2 *
4
3.
Mg+2
-b
Mg+*
4-
2Mg'
*
+
2CaC03
2
2Mg
i-t
a l t e r s t h e e x i s t i n g CaCO
3
+
Ca2
+2
+
-2
2CO3
structure
A s s t a t e d e a r l i e r , t h e c o n s t i u e n t s which enhancc t r e a t m e n t a r c P e a r s o n Hard
Acids which t e n d t o r e a c t w i t h o x i d a l s c a l e .
B i o i n a r t i va t i o n
B i o k l l l ranged from 0 t o 99 p e r c e n t f o r b o t h f e c a l and t o t a l c o l i f o r m s i n
secondary e f f l u e n t . E f f e c t i v e n e s s of t h i s i n a c t i v a t i o n f o r c o l i f o r m s
i n c r e a s e d w i t h flow a s shown i n F i g u r e 1. This t e n d s t o s u b s t a n t i a t e t h e
p r e m i s e t h a t b i o k i l l is due t o t h e a c t i v a t i o n of o r g a n i c s p r e s e n t i n
- 5-
1
Table 1.
A-Type Metal Cations
Electron configuration of
inert gas;
low polarizability;
"hard spheres"
(H+), Li+,Na+, K+,
Be2+ .Mg2+,Ca2+,
S r 2 +,A13+,Sc3'
L a 3 + , S i 4 + , Ti4',
z++ ,TI?
+
.
Classification ofMetal
Ions
Transition-Metal Cations
One to nine outer shell
e1ectrons;not spherically
ri ; h2+,
vsJ?e , Cr2+,
Fe2+, Co2+, Ni2+,
Cu2+, Ti3+, V3+,
Cr3+, Mn3+, Fe3+,
CO~J.
B-Type Metal Cation%
Electron number corresponds
to NiO, PdO, and PtO(10 or
1 2 outer shell electrons;
low electronegativity;
h i g h polarizability
" s o f t 8pheres" ,
Cut,Ag+ Au+ ,TI , G a t ,
Zn2+,Cd1+,Hg2+,Ph2*,
Sn2?,T13+,Au3+,
In3+,Bi3 +
.
+
According to Pearson's (1963) Hard and Soft Acids1
Hard Acids
Borderline
Soft Acids
A l l A-type metal cations
plus Cr3+,Mn3+ ,Fe3+,
All bivalent transition
metal cations plus
Zn2+,Pb2+,Bi 3 + ,
All B-type metal cations
minus Zn2+,Pb2+,Bi3+,
C O ~ + , U O,vo2+
~+
Also species such as
BF3,BCl j,SOj
RSO 2,RP02 ,CO:,
RCO+ ,R 3C'
SO,,NO+,B(CH,)
3
Preference of ligand atom:
N* P
o>> s
F>>C1
Qualitative generlaizations on stability sequence:
Cat ions
Cat ions
Stability
a
charge
radius
Irving-Wi$liams ?:der:
Mn2; < Fe l,',C;nz+
<Ni < Cu
+
Ligands :
F > O > N
=C1 > Br > I > S
OH- > RO- > RCOp
-
Ligands:
S > I > Br > C1
= N > O > F
1. R. C. Pearson, J.Amer. Chem. S O C . , 85, 353'3 (1963).
All metal atoms, bulk metals
I2,Br2,ICN,I+. B r
Table
2.
memica1 Groups Emploved w i t h U l t r a s o n i c s and E l e c t r o s t a t i c s
(which caused e x o t h e n n i c r e a c t i o n s )
Aromatic N i t r o g e n Croup
Amine Y i t r o g e n Croup
Glyrine
Hydroxylamine HC1
DL A l a n i n e
Phenylhydrazine HCl
P - T o l u i d i n e HC1
Benzami d e
O r g a n i c Acid I1
2 Furoic Acid
C h l o a c e t i c Acid
T a n n i c Acid
C i t r i c Acid
A n t h r a n i l i c Acid
Organic Acid
B u t y r i c Acid
O r a l i c Acid
? i a l e i c Acid
Lactic Acid
Aldehydes I
Aldehydes I1
Isonitrosoace tone
2,2,3 Trichlorbutanol
D i e t h y l Acetyl Acetaldehyde
Acetaldehyde
Butyraldehyde
Propioanaldehyde
Keytones I
Ketones I1
0-Aminopropiophenone
Methyl V i n y l Ketone
2-He~tanone
2-Propanone
2-Butanone
Diacetonamine
Chloroacetone
S u l f u r Group XI
Thiophenine
Ethoxyl S u l f i d e
Ethy Is u l f o n e
B u t y l 'rlydrogen S u l f a t e
2-Amino-Yethyl T h e v e t i n
S u l f u r Croup I
Cysteine
T h i o c y a n i c Acid
2-!4e~hylthiopscudourea
- 7-
>.
Y
.+
u.
C
w
U
C
u
c1
3
m
3
v)
U
U
V
.d
?
c
0
v)
N
cp
L,
U
U
C
N
2
ell
2
y.
N
br
3
3
bc
I:
U
4
C
.+
L,
I
0
Q
rA
z
N
0
V
&I
i
C
al
U
L
i
U
Y
v)
‘.
C
4
s
0
X
c
0
‘42
.d
\
0
N
secondary e f f l u e n t . A s i m i l a r phenomena was o b s e r v e d w i t h m i c r o b e s p r e s e n t
i n a s o f t d r i n k b o t t l e wanner i n an e a r l i e r p u b l i c a t i o n ( 1 6 ) .
An o b s e r v a t i o n of m a j o r i m p o r t a n c e , shown i n Table 3, was t h a t t h e u l t r a s o n i c
p r o c e s s was e f f e c t i v e t o 13% b i o i n a c t i v a t i o n f o r t o t a l c o l i f o r m and t h i s u l t r n s o n i c i n a c t i v a t i o n was a f u n c t i o n of i t s i n t e n s i t y and n o t i n f l u e n c e d by t h e
o r g a n i c s . T h i s is i l l u s t r a t e d i n F i g u r e 2. The e f f e c t i v e n e s s o f t h e e l e c t r o s t a t i c f i e l d was d i r e c t l y a f u n c t i o n of t h e s o l u b l e o r g a n i c s w i t h s u l f h y d r y l
o r g a n i c s and a r o m a t i c amines n o t e d t o b e t h e most e f f e c t i v e . The o r g a n i c s
a p p e a r e d t o be a c t i v a t e d by t h e e l e c t r o s t a t i c f i e l d w i t h a h e a t i n c r e a s e o f
one t o two k i l o c a l o r i e s p e r l i t e r o v e r t h e c o n t r o l The s u l f h y d r y l o r g a n i c s
a p p e a r t o b e good c a n d i d a t e s as d i s i n f e c t i o n a g e n t s due t o t h e i r low t o x i c i t y
t o humans, y e t t h e h y d r a z i n e compounds c o u l d p o t e n t i a l l y b e used b o t h a s
c o r r o s i v e i n h i b i t o r s ( 0 x y g e n s c a v e n g e r s ) and b i o c i d e s .
The o r g a n i c c h e m i c a l s t e s t e d b e l o n g t o t h e n i t r o g e n a r o m a t i c group and t h e
s u l f u r g r o u p . The;* inc!i:Jed
p h e n y l h y d r a z i n e HCL, p - t o l u d i n e HCL, benzamidcb,
The b a c t e r i a l m o n i t o r s
c y s t e i n e , t h i o c y a n i c a c i d , and 2-methyltheiopseudourea.
u s e d were t o t h e t o t a l c o l i f o r m t e s t , t h e f e c a l c o l i f o r m t e s t and t h e e n t r occcus t e s t .
I t was found t h a t p h e n y l h y d r a z i n e H C 1 a t a c o n c e n t r a t i o n of 20 ppm and a
t e m p e r a t u r e of 25OC and 3500 v o l t s e x h i b i t e d t h e b e s t a b i l i t y t o i n a c t i v a t e
t o t a l c o l i f o r m numbers. S t a t i s t i c a l t e s t s done t o d e t e r m i n e w h e t h e r o r n o t
there was a t r u e d i f f e r e n c e i n t h e s l o p e s of t h e test and c o n t r o l d a t a i n t h e
r e d u c t i o n o f t o t a l c o l i f o r m s w i t h t i m e showed t h a t a t t h e .95 l e v e l o f conf i d e n c e a d i f f e r e n c e i n s l o p e s d i d e x i s t . F u r t h e r t e s t i n g a l s o showed t h a t
t h e r e d u c t i o n of t o t a l c o l i f o r m s w i t h time f o l l o w e d f i r s t o r d e r k i n e t i c s .
T h i s d a t a shows t h a t p h e n y l h y d r a z i n e i n c o n j u n c t i o n w i t h e l e c t r o s t a t i c s undc,r
t h e p r e s c r i b e d c o n d i t i o n s does r e d u c e t o t a l c o l i f o r m p o p u l a t i o n s . The u s e of
e l e c t r o s t a t i c s a t 3400 v o l t s a l o n g w i t h t h e c h e m i c a l p h e n y l h y d r a z i n e HC1 c o u l d
p r o v e e f f e c t i v e i n s i t u a t i o n s where t o t a l c o l i f o r m p o p u l a t i o n s are a problem.
However, u n t i l t h e h e a l t h e f f e c t s o f t h e a c t i v a t e d o r g a n i c s have been a s c e r t a i n e d , t h i s a p p l i c a t i o n s h o u l d n o t b e used f o r p o t a b l e water. I n i n d u s t r i a l
situations, sulfhydryl
and h y d r a z i n e - l i k e compounds c o u l d b e p u t t o u s e
i n t h e b o t t l e - r i n s i n g i n d u s t r y o r p e r h a p s commercial water c l e a n i n g , s i n c e
h y d r a z i n e - l i k e compounds Flave been a c t i v e l y used a s oxygen s c a v e n g e r s i n b o i l e r
and c o o l i n g w a t e r t r c a t m n ? t
.
Corrosion Control
C o r r o s i o n is v e r y s i t e dependent no matter what i n d u s t r i a l w a t e r t r e a t m e n t
p r o c e s s is i n v o l v e d . I n d u s t r y s t i l l does n o t f u l l y u n d e r s t a n d t h e probltwi o f
corrosion.
I n i n v e s t i g a t i n g c o r r o s i v e s i t u a t i o n s , t h e environment and n a t u r e
of equipment must b e e v a l u a t e d t h o r o u g h l y . C o r r o s i v e s can b e d i v i d e d i r l t c i
e i g h t u n i q u e forms: u n i f o r m c o r r o s i o n s ( g e n e r a l a t t a c k ) 3 4 . 2 % ; galvanico r two m e t a l c o r r o s i o n ( 4 . 6 % ) ; c r e v i c e c o r r o s i o n ( 1 . 8 % ) ; p i t t i n g c o r r o s i o n ( 1 5 . 7 % ) ;
i n t e r g r a n u l a r c o r r o s i o n ( 1 0 . 2 % ) ; s e l e c t i v e l e a c h i n g ( 1 . 1 X ) ; e r o s i o n c o r r o s i o n (9,07!);
and stress c o r r o s i o n ( 2 3 . 4 % ) . T h e r e f o r e , t h e c o n t r o l of c o r r o s i o n i s a v e r y
complex s i t u a t i o n r e q u i r i n g a d e t e r m i n a t i o n of t h e t y p e of c o r r o s i o n , t h e n a t u r e
of t h e environment and knowledge of s p e c i f i c equipment b e i n g u t i l i z e d ( 3 1 , 3 2 ) .
The u s e o f t h e e l e c t r o s t a t i c process to i n h i b i t c o r r o s i o n h a s been met w i t h a
g r e a t d e a l of s k e p t i c i s m by t h e s c i e n t i f i c c o m u n i t y . As a r e s u l t o f f i e l d
-9-
Table 3.
Influence of Ultrasonics and/or ZlectrostaLics on the
Inactivation of Total Coliform in Wastewater Effluent
Effect of Uattage on Total Coliform Inactivation at a Constant
Temperature Flow and Exposure by Ultrasonics in Wastewater Effluent
A:
Test
Power Setting (watts)
Control
Test (unit operating)
Corrected K i l l
400
500
650
800
62%
3 7%
892
30%
38%
46%
-25%
-
90%
0%
Flow rate
8 liters per minute
Number of contacts with ultrasonics
Temperature
25OC
-
B:
3 ( r u n time
-
32%
38 rulnutes)
Effect of Flov Rate on Total Coliform Inactivation at a Constant
Temperature and Wattage by Ultrasonics in Wastewater Effluent
Test
Flow Rate (l/min)
Con t ro 1
Test (unit operating)
Corrected K i l l
-
1
52%
7 8%
26%
3
34 %
8
61%
12
53%
199.
76%
15 %
61:!
7%
Ultrasonics Power
800 Watts
Number of Contacts with Ultrasonics
Temperature
25°C
-
C:
-
7 8%
a ;:
-
54%
3 (run time varied)
Effect of Exposure o n Total Coliform Inactivity at a Constant
Temperature, Wattage and Flow.
Time of Exposure (minutes)
Test
11.7
Con t r o 1
Test (unit operating)
Corrected K i l l
49%
-- -
38
5.0%
63.3
88.7
59%
63%
652
64%
80%
14%
15%
16%
-
77%
18%
Ultrasonic Power
800 Watts
Flow rate
8 liters per minute
Temperature
25'C
D:
Effects of Electrostatics and Ultrasonics Processes in the
Inactivation of Total Coliforms in Sewage Effluents
Systems Energized
U1 t rasonics
Test
50%
65%
15%
Control
Test (unit operating)
Corrected K i l l
-
Electrostatic
4 7%
502
502
69::
3%
19?!
Ultrasonic Power = 800 Watts
Flov rate
8 liters per minute
Number of Contacts
3 (38 minute run time)
Temperature
25OC
- -
- 10-
Ecth
T a r c e n t Kill
Above Control
60
55
50
S u l f u r Croup I ('J/E)*
Total Yltrogcn (Aromatic and .Imine Y i r o g c n ) ( t i / E )
45
Aroma tic X i trogen (U/E
40
Aromatic Y i t r o q c n (Electrostatics)
S u l f u r Croup I (Elcctros t r t i c s )
35
30
25
20
15
Sulfur Croup I (Ultrasonics)
Organic A c i d s 11 (U/E)
u o m a t i c Y i t t o g e n (U1:ruonf cs), Ketones I (U/E)
O r p n i c Acids I (Ultrasonics)
10
Aldehydes I (U/E)
Aldehydes If ( U / E ) , S u l i u r Croup 11 (U/E)
Amine Yltrogcn ( U / E ) , Ketones I1 ( U / E )
5
0
*(U/Z)
-
Ultruoaics/Eltc:ros:ltics
-11-
-
s t d i e s , -the e l e c t r o s t a t i c p r o c e s s has been f m d t o c o n t r o l c o r r o s i o n i n
some c i i e s a n d n o t i n o t h e r s . The c o n t r o l o f . p e c r o a i o n is a f u n c t i o n of t h e
d i s s o l v a d OxygTq, pH, t e m p e r a t u r e , o x i d a t i o n - r e d u c t i o n p o t e n t i a l , w a t e r q u a l i t y ,
and t h e n r t d e ' o f t h e m i n e r a l s i n t h e c o o l i n g tower s y s t e m . I n two systems
i n L o u i s i a n a , t h e m e t a l l i c s u r f a c e had an o x i d e p r o t e c t i v e l a y e r form and t h u s
had no c o r r o s i o n problems, y e t i n Texas, a n o t h e r c o o l i n g tower s y s t e m h a d
problems o n c e t h e tower was d e s c a l e d ( 3 3 , 3 4 , 24).
I n b o i l e r s y s t e m s , e l e c t r o s t a t i c a l l y t r e a t e d w a t e r g e n e r a l l y does n o t need
oxygen s c a v e n g e r s i f t h i s t r e a t e d water h a s been deoxygenated by d e a e r a t i o n .
I f t h e w a t e r is d e a e r a t e d b e f o r e treatment, t h e t r e a t e d w a t e r n e e d s t h e
a d d i t i o n of oxygen s c a v e n g e r s . T h e r e f o r e , t h e t r e a t m e n t a p p e a r s t o enhance
t h e d e a e r a t i o n s t e p . However, f u r t h e r t e s t i n g s h o u l d b e c o n d u c t e d b e f o r e
s c a v e n g e r a g e n t s a r e e l i m i n a t e d from c o r r o s i o n c o n t r o l .
A s t u d y of t h e i n f l u e n c e of m a g n e t i c s on c o r r o s i o n c o n t r o l h a s p r o v i d e d
e v i d e n c e t h a t m a g n e t i c t r e a t m e n t i n h i b i t s t h e r a t e of c o r r o s i o n (35). I n
t h i s s t u d y , t h e r a t e of c o r r o s i o n was a f u n c t i o n of t h e w a t e r q u a l i t y and
t h e f i e l d s t r e n g t h . Maximum c o n t r o l was o b s e r v e d a t 500 Oe and t h i s c o n t r o l
was r e l a t e d t o t h e i n h i b i t i o n of t h e oxygen s a t u r a t i o n l e v e l s . T h u s , i t was
s p e c u l a t e d t h a t r e d u c t i o n i n c o r r o s i o n rates by m a g n e t i c f i e l d s was due t o
reduced d i s s o l v e d oxygen l e v e l s , y e t a major p r o d u c e r of m a g n e t i c s y s t e m s
c u r r e n t l y adds oxygen s c a v e n g e r s t o t h e c o o l i n g tower s y s t e m s .
I n summary, e l e c t r o s t a t i c p r o c e s s e s can r e d u c e t h e r a t e of c o r r o s i o n , b u t
t h e c o r r o s i o n problems are mainly due t o t h e e n v i r o n m e n t i n which t h e
equipment is l o c a t e d . T h e r e f o r e , c o r r o s i o n i n h i b i t o r s w i l l g e n e r a l l y b e
needed e x c e p t f o r s p e c i f i c e n v i r o n m e n t a l s i t u a t i o n s .
--F a c t o r s
C o n t r o l l i n g E l e c t ros t a t i c P r o c e s s e s
"liese f a c t o r s have been a s c e r t a i n e d from b o t h l a b o r a t o r y and f i e l d t e s t i n g .
T h i s is t h e most r e c e n t a v a i l a b l e d a t a as of September, 1981. The f a c t o r s
c o n t r o l l i n g e l e c t r o s t a t i c p r o c e s s e s have been c l a s s i f i e d i n t h r e e c a t e g o r i c s :
( 1 ) o p e r a t i o n a l and m a i n t e n a n c e p r o b l e m s ; (2) p r o c e s s r e l i a b i l i t y and
(3) p r o c e s s l i m i t a t i o n s .
O p e r a t i o n a l and Maintenance Problems
O p e r a t i o n a l and m a i n t e n a n c e problems have been n o t e d due t o t r a p p e d and
a c c u m u l a t e d s c a l e . The r e s u l t i n g problems can b e r e s o l v e d d e p e n d i n g upov
t h e s p e c i f i c t r e a t m e n t ( e . g . , b o i l e r water t r e a t m e n t and c o o l i n g water
t r e a t m e n t ) . As a r e s u l t o f b o i l e r water t r e a t m e n t by t h e e l e c t r o s t a t i c s
p r o c e s s e s , l a r g e p i e c e s of s c a l e have dropped from t h e u p p e r t u b e and tank
w a i l siiiiface m d have a c c u m u l a t e d on areas of t h e t u b e s below (on t o p of
lower b u n d l e s ) . I f t h i s s c a l e is n o t removed soon a f t e r i t c o l l e c t s , t h e
r e s u l t i n g " h o t s p o t s " w i l l r e q u i r e t u b e r e p l a c e m e n t and e x p e n s i v e down-time.
Frequent i n s p e c t i o n and, i f n e c e s s a r y , s c a l e d e p o s i t removal by t h e c u s t o m e r
is s t r o n g l y recommended. Accumulation of s c a l e i n t h e bottom of t h e b o i l e r
can a l s o o c c u r a s c l e a n i n g p r o g r e s s e s . T h i s can c l o g blowdown o p e n i n g s and
a l s o c a u s e a b u i l d up i n s o l u b l e s a l t c o n c e n t r a t i o n s which c o u l d r e s u l t i n
p r e c i p i t a t i o n f o r a p a r t i c u l a r b o i l e r s y s t e m . I f c a r e f u l and r e g u l a r
m a i n t e n a n c e is n o t c a r r i e d o u t , a renewed s c a l i n g problem is l i k e l y t o o c c u r .
The h i g h s o l i d s i n c o o l i n g towers can c a u s e two problems: (1) c l o g g i n g of
downstream equipment and ( 2 ) i n c r e a s e d s c a l i n g . The c l o g g i n g of downstream
-12-
equipment is a r e s u l t of t h e f l a k i n g o f a s o l i d from t h e c o o l i n g tower.
I n a d d i t i o n , t h e s e suspended s o l i d s can i n c r e a s e t h e s o l u b l e s a l t l e v e l s
t o above maximum c a p a c i t y l i m i t s and t h i s h i g h e r l e v e l of s o l u b l e s a l t s
w i l l c a u s e i n c r e a s e d p r e c i p i t a t i o n . The above problems can b e r e s o l v e d
by f i l t e r i n g t h e suspended s o l i d s .
Process R e l i a b i l i t y
The r e l i a b i l i t y and c a p a b i l i t y of t h e p r o c e s s e s were o b s e r v e d i n r e l a t i o n
t o t h e performance of t h e t r a n s d u c e r and power pack components. These
components as p r o v i d e d by t h e same m a n u f a c t u r e r performed e r r a t i c a l l y ;
t h e t r a n s m i t t e d f r e q u e n c i e s v a r i e d a c r o s s t h e e n t i r e d e s i g n r a n g e and f o r
d i f f e r e n t t i m e d u r a t i o n s . Some of t h e c i r c u i t r y i n t h e power pack cons i s t e n t l y f a i l e d due t o d e s i g n f a u l t s . However, much v a l i d d a t a was
o b t a i n e d a f t e r c l o s e m o n i t o r i n g of t h i s equipment.
O t h e r m a n u f a c t u r e r s have p r o v i d e d p r o v e n and r e l i a b l e power s u p p l y s y s t e m s
t h a t have n o t o n l y m e t t h e d e s i g n r e q u i r e m e n t s , b u t a l l o w e d f o r o p t i m i z a t i o n
o f t h e s y s t e m . These m a n u f a c t u r e r s have t a k e n a g r e a t d e a l of e x p e r i e n c e
from t h e e l e c t r o s t a t i c s p r e c i p i t a t o r s u t i l i z e d f o r a i r s y s t e m s .
P r o p e r placement o f t h e u n i t is i n f l u e n c e d b y b o t h t h e p r o c e s s b e i n g t r e a t e d
and t h e placement b e f o r e o r a f t e r t h e pump. Many f a i l u r e s have been a
result of t h i s v e r y problem. Major problems have r e s u l t e d when an e l e c t r o s t a t i c s p r o c e s s was i n s t a l l e d on r i n s e t a n k s o f b o t t l e washing and r i n s e
machines. I n g e n e r a l , t h e r e was a b u i l d up of s o l u b l e s a l t s ( p a r t i c u l a r l y
a l k a l i n i t y ) n o t e d and u n c o n t r o l l a b l e pH f l u c t u a t i o n s (due t o c a u s t i c r e s i d u e s
from p r e - r i n s e w a t c r and s o a k t a n k s ) . T h i s pH f l u c t u a t i o n c a n s c a l e up
t h e u n i t by i t s e l f b e c a u s e t h e s o l u t i o n was n e a r t h e s o l u b i l i t y l i m i t s f o r
e f f e c t i v e u n i t o p e r a t i o n a t pH 8. T h i s pH i n c r e a s e (8 t o 10) i n c r e a s e d
t h e c a r b o n a t e c o n c e n t r a t i o n a p p o x i m a t e l y 100 times (which w i l l c a u s e p r e c i p i t a t i o n due t o t h e common i o n e f f e c t ) . T h i s s i t u a t i o n can b e a v o i d e d by
i n s t a l l i n g t h e u n i t on t h e f r e s h water s u p p l y ( f i n a l r i n s e l i n e ) . When
i t is i n s t a l l e d i n t h i s l o c a t i o n , b o t h t h e upper and l o w e r s p r a y h e a d s
must b e s u p p l i e d by t h e t r e a t e d water. By p l a c i n g t h e u n i t b e f o r e t h e pump
( o n i t s vacuum s i d e ) , t h e r e s u l t i n g p r e s s u r e h a s been found t o b e f a r l e s s
t h a n 85 p s f . Thereby, t h e e f f e c t i v e n e s s o f t h i s p r o c e s s h a s been g r e a t l y
i n c r e a s e d . O t h e r e l e c t r o s t a t i c p r o c e s s e s which do n o t u s e u l t r a s o n i c
t r a n s d u c e r s o r have a f l o a t i n g t y p e e l e c t r o d e have been a b l e t o o p e r a t e a t
p r e s s u r e up t o 250 p s i .
Process l i m i t a t i o n s
P r o c e s s l i m i t a t i o n s i n c l u d e p h y s i c a l f a c c o r s , c h e m i c a l p a r a m e t e r s , and
new s o l u b i l i t y l i m i t a t i o n s . The p h y s i c a l f a c t o r s a r e p r e s s u r e , t e m p e r a t u r e ,
and r e s i d u e from t r e a t m e n t . A t p r e s e n t , ultrasonic/electrostatic u n i t s
a r e r a t e d f o r 85 p s i a t 14S°F maximum p r e s s u r e and t e m p e r a t u r e . The 85 p s i
is t h e l i m i t i n g p r e s s u r e f o r t h e e f f e c t i v e t r e a t m e n t by t h e u l t r a s o n i c
0
t r a n s d u c e r a n d t h e 145 F I s t h e maximum t e m p e r a t u r e a t which a submerged
e l e c t r o d e w i l l o p e r a t e e f f i c i e n t l y . I f t h e p r o c e s s is o p e r a t e d abovc.
e i t h e r or b o t h l i m i t s , t r e a t m e n t is r a d i c a l l y reduced. Recent e l e c t r o s t a t i c
p r o c e s s e s can o p e r a t e a t p r e s s u r e s g r e a t e r t h a n 200 p s i b e c a u s e t h e e l e c t r o d e
i s n o t f l o a t i n g and no t r a n s d u c e r is u t i l i z e d . However, i t must b e
o p e r a t e d a t less t h a n 250 p s i due t o t h e e l e c t r o d e c g a t i n g l i m i t s . The
c o a t i n g h a s a t e m p e r a t u r e l i m i t o f a p p r o x i m a t e l y 250 F. I t must b e n o t e d
-13-
t h a t these a b i o t i c f a c t o r s i n f l u e n c e t h e treatment w i t h i n t h e p r o c e s s .
A f t e r t h i s t r e a t m E n t , t h e temperature and p r e s s u r e s of t r e a t e d w a t e r c a n
b e r a i s e d t o ZOO+ F and 200+ p s i . If t h e water h a s less t h a n a s i x s e c o n d
r e s i d e n c e time i n t h e u n i t , t h e e f f e c t i v e t r e a t m e n t can b e g r e a t l y r e d u c e d .
Although t h e r e a r e times when t r e a t m e n t can be e f f e c t i v e w i t h a l o w e r
r e s i d e n c e ' t i m e , t h i s i s o n l y f e a s i b l e under s p e c i f i c s i t u a t i o n s ( i . e , w a t e r
q u a l i t y and s c a l e d e n v i r o n m e n t s ) .
From l a b o r a t o r y and f i e l d r e s u l t s , t r e a t e d
w a t e r from t h e ultrasonic/electrostatic p r o c e s s r e t a i n s e f f e c t i v e n e s s f r o m
30 to 60 m i n u t e s a f t e r d i s c h a r g e from t h e t r e a t m e n t p r o c e s s . T r e a t e d water
must b e used w i t h i n t h i s time p e r i o d t o o b t a i n p o s s i b l e d e s c a l i n g .
The c h e m i c a l p a r a m e t e r s o f much c o n c e r n are suspended s o l i d s and o r g a n i c
c o n t e n t . A s t h e suspended s o l i d s c o n c e n t r a t i o n i n c r e a s e s t o g r e a t e r t h a n
20 mg/l ( o r g a n i c , l e . , v o l a t i l e suspended s o l i d s , o r i n o r g a n i c , i . e . , i n e r t
s u s p e n d e d s o l i d s ) , t h e e f f e c t i v e n e s s of t h e e l e c t r o s t a t i c p r o c e s s i s
s i g n i f i c a n t l y reduced or c o m p l e t e l y i n h i b i t e d . T h e r e f o r e , i t i s recommended
t h a t water of t h i s q u a l i t y b e p r e t r e a t e d ( i . e , f i l t r a t i o n , s e d i m e n t a t i o n ,
e t c , ) b e f o r e p a s s i n g t h r o u g h t h e t r e a t m e n t u n i t . The i n f l u e n c e of d i s s o l v e d
o r g a n i c s on e l e c t r o s t a t i c s t e n d s t o v a r y . I n some i n s t a n c e s , t h e o r g a n i c s
a c t a s a b i o c i d e and r e d u c e b i o l o g i c a l a c t i v i t y , b u t i n g e n e r a l , i t h a s been
e f f e c t i v e t rea tmen t
noted t h a t i n c r e a s e s i n dissolved organics tend to reduce
by t h e s y s t e m . C u r r e n t l y , i f t h e d i s s o l v e d o r g a n i c s are greater t h a n 20 mg/l
a s c a r b o n , t h e e f f + c i e n c y o f t h e p r o c e s s c a n b e g r e a t l y r e d u c e d and a t 50 mr/l
a s c a r b o n , i t is c o m p l e t e l y i n h i b i t e d . Recent s t u d i e s h a v e n o t e d t h a t
t h e o r g a n i c s can e i t h e r i n d u c e o r i n h i b i t t r e a t m e n t . O i l and g r e a s e w i l l
r e a c t s i m i l a r l y ( 2 f l mg/1 and 50 mg/l) b u t g e n e r a l l y a r e l i m i t e d t o l o w e r
v a l u e s ( 10 t o 25 mg/l) due t o p o s s i b l e c o a t i n g of t h e e l e c t r o d e .
0
F i n a l l y , t h e s o l u b i l i t y l i m i t f o r c a l c i u m c a r b o n a t e a t 100 F i s a p p r o x i m a t e l v
400 mg/l as c a l c i u m c a r b o n a t e . T h i s is a t e n - f o l d i n c r e a s e i n s o l u b i l i t y
(from t h e 40.0 mg/l as c a l c i u m c a r b o n a t e ) f o r s y s t e m s w i t h t h e e l e c t r o s t a t i c s
p r o c e s s h a v i n g a c a p a c i t a n c e on t h e e l e c t r o d e of 7000 v o l t s . The s o l u b i l i t y
l i m i t f o r c a l c i u m c a r b o n a t e h a s been n o t e d t o d r o p from t e n - f o l d t o s i x - f o l d
w i t h a d r o p i n c a p a c i t a n c e from 7000 v o l t s t o 3500 v o l t s on t h e e l e c t r o d e .
P r o b a b l y t h i s p r o c e s s e f f e c t on s o l u b i l i t y s h o u l d b e s i m i l a r f o r o t h e r s a l t s
( c o a g u l a t i v e s a l t s , f e r r i c ions, magnesium i o n , c h l o r i d e s , e t c . ) and
should be considered b e f o r e u t i l i z i n g t h i s system f o r o t h e r d e s c a l i n g a p p l i c a t i o n s
SUMMARY
The d e s c a l i n g a n d / o r s c a l e i n h i b i t i o n p r o c e s s is h i g h l y complex and is
governed by c h e m i c a l r e a c t i o n s of several areas o f c h e m i s t r y . American and
R u s s i a n r e s e a r c h showed t h a t c e r t a i n phenomena i n f l u e n c e t h e d e s c a l i n g p r o c e s s :
1) t h e b u i l d - u p of s l u d g e i n t r e a t e d water; 2) i n c r e a e e d e f f i c i e n c y a f t e r
the a d d i t i o n of soltible ircn and m g n e s i u m ; 3) water q u a l i t y ; a n d , 4 ) t h e
z e t a p o t e n t i a l . I n t h i s s t u d y , a t e m p e r a t u r e phenomenon was n o t e d . I t i s
recommended t h a t r e s e a r c h e r s and m a n u f a c t u r e r s c o n s i d e r t h e s e phenomena i n
f u t u r e r e s e a r c h and b e f o r e p r o v i d i n g e l e c t r o s t a t i c equipment f o r v a r i o u s
field applications.
The b i o i n a c t i v a t i o n h a s b e e n n o t e d t o b e a f u n c t i o n o f t h e s o l u b l e o r g a n i c s
and t h e i n t e n s t i y o f t h e e l e c t r o s t a t i c f i e l d . , The s u l f h y d r y l o r g a n i c and
o r g a n o h y d r a z i n e i n d i c a t e d p o t e n t i a l t o i n a c t i v a t e m i c r o b e s . The d i s i n f e c t i o n
by u l t r a s o n i c and e l e c t r o s t a t i c p r o c e s s e s i s c a p s u l a t e d i n T a b l e 4 .
-14-
T a b l e 4. Summary of E x p e r i m e n t a l Data Concerning B i o k i l l f o r U l t r a s o n i c s /
E l e c t r o s t a t i c s Processes
I n d i c a t o r 3rqanisms
FACTORS
Total
Colif o m s
Fecal
C o l i f 0m s
To t a l
Bac t e r i a
Ap p a re n t 1y
optimum
flow
Apparently
op t i m u m
flow
App a ren t1
optimum
flow
e f f e ct i v e ness
< levels
will>
e f f e ctiveness
< levels
will>
effectiveness
levels
will>
effectiveness
< levels
wi 11>
efiectivt
ness
< l eve Is
will>
effectiveness
<levels
will>
effectivencss
<levels
will>
ef f ectiveness
< l a v e Is
will>
effectiveness
Depends on
Dissolved
Solids
Depends on
Dissolved
Solids
Depends on
Dissolved
Solids
Depends on
D i ss o l v e d
Solids
Depends o
Dissolved
Solids
May depend
on o r g a n i c s
Nay depend
on o r g a n i c s
Depends on
organics
Depends on
organics
Depends
organics
Ap p a r en t 1y
Optimum
Frequency
Appa r en t l y
Optimum
Frequency
Apparently
Op t i m u m
Frequency
Apparently
Optimum
Frequency
Ap pa r e n t 1
op t i s m
Frequency
>Intensity
>
effectiveness
>Intensity
will >
effectiveness
>Intensity
will >
effectiveness
>Exposure
will>
cffectiveness
>Exposure
will>
effective-
>Exposure
will>
e f f e c t i veness
>ExposurE
vill>
effective
ness
>Duration
will>
effective-
>Durat i o n
will>
effective-
>Dura t i o n
will<
e f f e c t ive-
ness
ness
ness
>Durat i o n
will<
effectiveness
>Duratior
will<
ef fectivc
ness
>Temperature
will>
effectiveness
>Tempera t u r e
will>
e f f e c tiveness
>Temperat
wi 11>
ef f e c t i v t
ness
No e f f e c t
<Effectiveness
<Effectiveness
<Effecti'
ness
No e f f e c t
No e f f e c t
No e f f e c t
No e f f e c
No e f f e c t
>Field
vill>
ef f ective-
>Field
will>
ness
ness
>Field
will>
ef f e c t i v
ness
.Toxocara
Eggs
Ascaris
Eggs
Flow
>Flow w i 1l< A p p a r e n t l y
effectiveop t i m u m
ness
flow
Initial
Concentration
<levels
w i 11>
Suspended
Solids
Total
Dissolved
Solids
s
Organics
I Frequency
>Intensity
will>
e f f e c t iveness
W i l l
>Exposure
will >
effectiveness
Duration
Tempe ra t u r e
>Temperature >Tempe ra t u r e
will>
will>
effectivecffectiveness
ness
Ac clima t i za t ion
No e f f e c t
Prcrsu re
No e f f e c t
Induced F i e l d
No e f f e c t
*
-15-
ness
effective-
<levels
will>
effective
ness
>Intensic
will>
cf fectlve
ness
The c o n t r o l of c o r r o s i o n a p p e a r s t o b e s y s t e m and s i t e d e p e n d e n t . The
e l e c t r o s t a t i c p r o c e s s e s t e n d t o r e d u c e d i s s o l v e d oxygen l e v e l s and work
w e l l w i t h oxygen s F a v e n g e r s such as h y d r a z i n e .
The e l e c t r o s t a t i c method of water t r e a t m e n t is l i m i t e d i n a p p l i c a t i o n by
p r o c e s s l i m i t a t i o n s , l o c a t i o n of t h e equipment and o p e r a t i o n and m a i n t e n a n c e
problems.
E l e c t r o s t a t i c t r e a t m e n t s y s t e m s are g e n e r a l l y l i m i t e d by t e m p e r a t u r e , p r e s s u r e
and s o l u b i l i t y . Where t h e maximum l e v e l s o f t h e s e p a r a m e t e r s are e x c e e d e d ,
l i t t l e or n o t r e a t m e n t is e f f e c t e d . Flow r a t e is a l s o a n i m p o r t a n t f a c t o r .
The water must h a v e a minimum e x p o s u r e time t o t h e e l e c t r o s t a t i c f i e l d of
about s i x seconds.
O t h e r l i m i t a t i o n s a r e h i g h suspended s o l i d s and o r g a n i c c o n t e n t a s w e l l a s
o i l and g r e a s e , F l u c t u a t i o n s i n pH a l s o l i m i t t h e e f f e c t i v e n e s s .
Placement ( l o c a t i o n ) of t h e e l e c t r o s t a t i c equipment can a l s o d e t e r m i n e t h e
d e g r e e o f e f f e c t i v e n e s s of t h e t r e a t m n e t . Exposure of t h i s equipment t o any
of t h e l i m i t i n g c o n d i t i o n s l i s t e d w i l l e i t h e r d e c r e a s e o r e l i m i n a t e t h e
e f f e c t s of t h e t r e a t m e n t .
O p e r a t i o n and m a i n t e n a n c e l i m i t a t i o n s a r e d u e p r i m a r i l y t o t h e b u i l d up
of l o o s e s c a l e i n t h e t r e a t e d equipment. I f t h e s c a l e is n o t removed,
s o l u b l e s a l t c o n c e n t r a t i o n b u i l d up and h o t s p o t s w i l l form on t h e s u r f a c e
of h e a t exchange t u b e s . Renewed s c a l i n g and c l o g g i n g c a n a l s o t a k e p l a c e .
- 16-
REFERENCES
1.
Welder, B.Q. and Partridge, E.P., "Practical Performance of Water
Industrial
E
VOl. 5 0 ,
Condi t ion ing Gadget
pp 954-960 (H.y 1954).
SI',
* I
2.
Eliassen, R., Skrinde, P.T., and Davis, W.B., "Experimental Performance of 'Mracle'Water Conditioners", Journal American Water Works
Association, Vol. 50, pp. 1371-1384 (Oct. 1958).
3.
Dearborn Chemical Division of Chemed Corporation, "Watch Out for a
New Round of Water Treatnent 'Gadgets'," Water Conditionina (July,
1977).
4.
Dromgoole, J.C., and Forbes, M.C. "The Fatal Lure of Water
Treatment Gadgets". Presented at the 40th Annual International
Water Conference, Pittsburgh, PA. (Oct. 31,1979).
5.
Wilkes, J.F., and Brown, R., "Water Conditioning Devices - An
Update", Presented zt the 40th Annual International Water Conference,
Pittsburgh, PA. (Oct. 31, 1979).
6.
Joshi, K.M., and Kamat, P.V., "The Effect of Magnetic Fields on the
pH of Water", J. Indiana Chem. COC., p. 4 3 (1966).
7.
Kirgintsev, A.N., "Mechanism of the Hagnetic Treatment of Liquids",
Zh. Fit. Khim., Vol. 45(4), pp. 857-859 (1971).
8.
Lazorenko, B. R. , and Bautysh, L . A . , "Properties of Water Subjected
to the Action of Electrical or Magnetic Fields", Elektron Obrab.
Mater., No. 3 pp 46-48 (1970).
9.
Quickenden, T.L., Betts, D.M., Cole, B., and Noble, M., "The Effect
of Magnetic Fields o n the pH of Water", The Journal of Physical
Chemistry, Vol. 75(18), pp. 2839-2831 (1971).
10.
Kaubikova, H., "Research Regarding the Effects of Nagnetic Treatment on Water", The Institute of Hydraulic Research, Praque,
Czechoslovakia (Feb., 1969).
11.
Hokkaido University, Internal Report Japan (no date).
12.
Ar, E., "Study of Electric and Magnetic Treatment of Water to
Prevent Scaling and Corrosion; Biological and ?ledical Implications",
Partial contents of a Proposal releasing research results, U. of
Michigar! (Mar. 1973).
13.
Duffy, E.A., "Investigation of Magnetic Water Treatment Devices",
Dissertation presented to the Graduate School of Cleason University
(Aug., 1977).
14.
Krajiic, G., and Milosevlc-Kraj, P I . , "Magnetic Field Conditioning of
.Industrial Waters", Presented at the 40th Annual International
Water Cbnference, Pitts. PA. (Oct. 31, 1979).
-17-
15. Cheremisinoff, N . P . , Chermisinoff, P.N., and Tratter, R . B . , Chemical
and Non-Chemical Disinfection, Ann Arbor Science Publishers, Inc.,
Ann Arbor, Hich. p p 1-172 (1981).
16. Reimers, R . S . , deKernion, P.S., Robtdeau, F.C., "Appllcatfon of
Ultrasonics and Electrostatics
An innovative and Energy Saving
Approach to Industrial Water Treatment", Symposium on Environmental
and Energy Saving Process supported by Department of Energy
(Dec. , 1979).
-
17. Dakubu, S., "Cell Inactivation by Ultrasound", Biotechnology and
Bioengineering, Vol. 18 pp 465-471 (1976).
18. Croakley, W.T., Bater, A.J., and Lloyd, D. "Disruption of Microorganisms" Advances in Microbial Physiology edited by Rose, A.H.,
and Tempest, D.W., Vol. 16, Academic Press, N.Y., p p . 279-341
(1977).
19. Schmitt, F.O., and Uhlemeyer, B., "The Mechanism of Lethal Effects
o f Ultrasonic Radiation", Proc. SOC. Expcl. B i o l . F l e d . , Vol. 2 7 ( 7 )
pp. 626-628 (1930).
20.
Ordonez, J.A., and Burgos, J., "Effect of Ultrasonic Waves on the
Heat Resistance Bacillus Spores", Applied and Environmental Microbiology, Vol. 32(1), pp. 183-184 (July, 1 9 7 6 ) .
21.
Wang, L.K., Wang, M.H., and Peery, G . C . , "General Theories of
Chemical Disinfection and Sterilization of Sudge
Part 2 * ' ,
Water and Sewage Works, Vol. 125(8) pp. 58-63 (August, 1978).
22.
Murry, E.J., An Ultrasound Future or a Sound Sleep Part 111- Uses
in Variety", Chemical Technology-, Vol. 5, pp. 376-381 (June, 1975).
23.
Quellette, R.P., King, J.S., and Cheremisinoff, P.N., Electrotechnology Volume I. Wastewater Treatment and Separation Methods, Ann
Arbor Science Publishers Inc. Ann Arbor, Michigan, p.609 (1978).
24.
Reimers, R. S., deKernion, P . S . , Robedeau, F.C. and Leftwich, D.B.,
"A Viable Approach to Water and Waste Treatment
Part I and 11",
-
-
Water Technology, pp. 44-47, 64-65, (May-June, 1980) and 26-32,
60-65 (July-Aug. 1980)
25.
Means, F. A . and Mour, A.A., "How Electrostatics Water Treatment
Worksii, Journal of the 'n'atiiinal A s s o c i a t ? o n ~f Power Engineersi
May, 1975.
26.
Biocheno, V.A. and Spogin, L.G., "Theory of Magnetic Water Treatment", Journal of Engineering Physics, Vol. 33 ( 2 ) , pp. 980-984
Russian (August, 1977).
27.
Hibben, S. G., Magnetic Treatment of Water, NTIS Report No. AA-757-887,
Washington Dc, June (1973).
-1a
,
28.
Shahko A. I . , S h i r y a y e v a and A . S. A v e t i s o v , "The Use of a Magnetic
F i e l d i n t h e S o f t e n i n g of Water", I z v e s t i y a , V I Z o v . SSR. No. 1 2 ,
Moscow, 1966.
29.
K l a s s e n , Doctor of T e c h n i c a l S c i e n c e s , I n s t i t u t e of M i n e r a l F u e l s
o f t h e USSR Academy of S c i e n c e s , Moscow, Khimiya i Z h i z n ' , R u s s i a n ,
No. 9 , September, pp.24-27 (1969).
%.
Stamm, W. and Morgan, J.J., A q u a t i c C h e m i s t r y
An I n t r o d u c t i o n
Emphasizing Chemical E q u i l i b r i a i n N a t u r a l Waters, J o h n Wiley a n d
Sons, 2 n d , E d i t i o n , New York (1891) p.780.
31.
P l u d e k , V. R . , Design and C o r r o s i o n C o n t r o l . J o h n Wiley and S o n s ,
New York, (1977) p. 383.
32.
F o n t a n a , M.G. and Greene, N . D . , C o r r o s i o n E n g i n e e r i n g . McGraw H i l l
Book Company, 2nd E d i t i o n , New York ( 1 9 7 8 1 , p. 465.
33.
Reimers, R.S. and deKernion, P.S., "The A p p l i c a t i o n o f Aqua-Scrubber's
Ultrasonic/Electrostatic Treatment of a C o o l i n g Tower and Heat
Exchanger System o f M t . A i r y R e f i n i n g Company", R e p o r t by AquaS c r u b b e r C o r p o r a t i o n t o M t . A i r y R e f i n e r y , Garyville LA ( J a n u a r y , 1 9 8 1 ) .
34.
deKernion, P.S., Unpublished d a t a f o r Aqua-Scrubber C o r p o r a t i o n ,
Kenner LA (1980).
35.
T o b e n i k h i n , E. F., P r o n i n , Z.F., and Rybal'Chenko, U.S., "The E f f e c t
of a Magnetic F i e l d on t h e C o r r o i o s n of S t e e l i n a C o r r o s i v e Medium",
T e p l e o n e r g e t i k a , Vol. 19 ( l o ) , pp. 9-71, (1972).
-
-19-