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Follow the bouncing ball…
Patents Follow the bouncing ball... Water p u r i f i c a t i o n m e m b r a n e s often b e c o m e fouled w i t h s l i m e s ff the r a w w a t e r q u a l i t y is low. C h e m i c a l t r e a t m e n t to c l e a n the m e m b r a n e can generate water w h i c h t h e n itself m a y n e e d to b e treated. M e c h a n i c a l r e m o v a l of the s l i m e d e p e n d s o n t h e a c c e s s i b i l i t y of t h e m e m b r a n e s : i n s i d e a p r e s s u r e vessel, for e x a m p l e , is n o t t h e b e s t place to c a r r y o u t m a n u a l or m e c h a n i c a l c l e a n i n g of m e m b r a n e s . E b a r a of J a p a n p r o p o s e s the u s e of s m a l l b a i l s a n d air b u b b l e s to c l e a n m e m b r a n e s i n s u c h areas. As s h o w n i n F i g u r e 5, t h e vessel c o n t a i n s several c o n v e n t i o n a l m e m b r a n e s . It also holds n u m e r o u s small balls (5-20 mm diameter) which have d e n s i t i e s close to 1.0 g / c m 3. I n n o r m a l o p e r a t i o n t h e baUs do n o t i n t e r f e r e w i t h t h e o p e r a t i o n of the m e m b r a n e i n a n y way. W h e n it b e c o m e s fouled, however, air is i n t r o d u c e d i n t o t h e vessel, a n d initially t h e w a t e r level is lowered. T h e n air is allowed to flow t h r o u g h the vessel, r e l e a s e d a s s m a l l b u b b l e s from the diffuser at the b a s e of t h e vessel. The air agitates the balls a n d they clean the s u r f a c e s of t h e m e m b r a n e s at the top of t h e w a t e r level. By a d j u s t i n g the w a t e r level, all t h e w o r k i n g s u r f a c e s of the m e m b r a n e s c a n be c l e a n e d . O n l y a s m a l l v o l u m e of w a t e r n e e d b e d r a w n off, w h i c h c o n t a i n s o n l y
treated water
_
$1~
membrane~
t raw water out
alrv~
raw
A airdrainvadve
- ~
~,m~
in
FEED
frame plate
tie
m P m b r a e e pack frame
V
EATE OUT
~ i CONCENTRATE OUT
Figure 6: Rotary modular m e m b r a n e
the biological m a t e r i a l a n d c a n therefore be d i s p o s e d of easily.
Patent number: J P 4 1 2 6 5 2 8 Date: 27 April 1992 Inventor: K. N a g a n a m i Applicant: E b a r a Infflco Co. Ltd
Rotary membrane pack replacement A n i n c r e a s e in the p r e s s u r e difference a c r o s s a m e m b r a n e will speed u p diffusion a n d increase the o u t p u t of the device, at l e a s t u p to the p o i n t w h e r e the m e m b r a n e r u p t u r e s . This r e q u i r e s s o m e p a r t of the a p p a r a t u s to b e c o n s t r u c t e d a s a p r e s s u r e vessel, w h i c h is expensive a n d incurs a greater r i g o u r i n safety r e g u l a t i o n . A n o t h e r m e a n s of p r o d u c i n g a similar increase in the driving force for a s e p a r a t i o n p r o c e s s is to s p i n the a p p a r a t u s rapidly: to u s e c e n t r i f u g a l force.
W h e n t h i s is d o n e , a s with most separation processes, t h e m e m b r a n e or filter n e e d s to be serviced or r e p l a c e d from time to time. The p r o b l e m s a s s o c i a t e d with this included extensive r e b a l a n c i n g of t h e m u l t i p l e membrane packs that make up t h e r o t a r y filter a n d e x t e n s i v e d i s m a n t l i n g of t h e rotor to r e m o v e s o m e or all of t h e h u n d r e d s of individual m e m b r a n e packs. The d e s i g n s h o w n h e r e i n Figure 6 circumvents these p r o b l e m s : e a c h of the eight m e m b r a n e p a c k s e g m e n t s Is held i n place b y a tie b a r w h i c h is fixed to the e n d p l a t e s , a n d w h i c h compresses the small m e m b r a n e p a c k s w h i c h go to m a k e u p e a c h s e g m e n t . The filter r o t a t e s i n s i d e a c a s i n g w h i c h c a n be r a p i d l y o p e n e d to g a i n a c c e s s to the filter s e g m e n t s . Removal, r e i n s t a l l a t i o n a n d r e b a l a n c i n g a r e therefore m u c h more quickly completed.
Patent number: US 5 1 1 4 5 8 8 Date: 19 May 1992 Inventor: W. G r e e n e Applicant: A q u a t e c h n o l o g y R e s o u r c e M a n a g e m e n t Inc.
Figure 5: Filter cleaning device
M e m b r a n e T e c h n o l o g y No. 3 4
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treated water
_
$1~
membrane~
t raw water out
alrv~
raw
A airdrainvadve
- ~
~,m~
in
FEED
frame plate
tie
m P m b r a e e pack frame
V
EATE OUT
~ i CONCENTRATE OUT
Figure 6: Rotary modular m e m b r a n e
the biological m a t e r i a l a n d c a n therefore be d i s p o s e d of easily.
Patent number: J P 4 1 2 6 5 2 8 Date: 27 April 1992 Inventor: K. N a g a n a m i Applicant: E b a r a Infflco Co. Ltd
Rotary membrane pack replacement A n i n c r e a s e in the p r e s s u r e difference a c r o s s a m e m b r a n e will speed u p diffusion a n d increase the o u t p u t of the device, at l e a s t u p to the p o i n t w h e r e the m e m b r a n e r u p t u r e s . This r e q u i r e s s o m e p a r t of the a p p a r a t u s to b e c o n s t r u c t e d a s a p r e s s u r e vessel, w h i c h is expensive a n d incurs a greater r i g o u r i n safety r e g u l a t i o n . A n o t h e r m e a n s of p r o d u c i n g a similar increase in the driving force for a s e p a r a t i o n p r o c e s s is to s p i n the a p p a r a t u s rapidly: to u s e c e n t r i f u g a l force.
W h e n t h i s is d o n e , a s with most separation processes, t h e m e m b r a n e or filter n e e d s to be serviced or r e p l a c e d from time to time. The p r o b l e m s a s s o c i a t e d with this included extensive r e b a l a n c i n g of t h e m u l t i p l e membrane packs that make up t h e r o t a r y filter a n d e x t e n s i v e d i s m a n t l i n g of t h e rotor to r e m o v e s o m e or all of t h e h u n d r e d s of individual m e m b r a n e packs. The d e s i g n s h o w n h e r e i n Figure 6 circumvents these p r o b l e m s : e a c h of the eight m e m b r a n e p a c k s e g m e n t s Is held i n place b y a tie b a r w h i c h is fixed to the e n d p l a t e s , a n d w h i c h compresses the small m e m b r a n e p a c k s w h i c h go to m a k e u p e a c h s e g m e n t . The filter r o t a t e s i n s i d e a c a s i n g w h i c h c a n be r a p i d l y o p e n e d to g a i n a c c e s s to the filter s e g m e n t s . Removal, r e i n s t a l l a t i o n a n d r e b a l a n c i n g a r e therefore m u c h more quickly completed.
Patent number: US 5 1 1 4 5 8 8 Date: 19 May 1992 Inventor: W. G r e e n e Applicant: A q u a t e c h n o l o g y R e s o u r c e M a n a g e m e n t Inc.
Figure 5: Filter cleaning device
M e m b r a n e T e c h n o l o g y No. 3 4
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