NALCO

RECENT DEVELOPMENTS IN BEET TRANSPORT WATER MANAGEMENT

BY DA VID O LARSON SENIOR ACCOUNT MANAGER

AND JOHN M HELGE DISTRICT SALES MANAGER

NALCO CHEMICAL CO ONE NALCO CENTER NAPERVILLE IL 60566

Personal chemistry makes the difference

1 32

INTRODUCTION

If you were to ask the Operations Manager of a typical Northern United States sugar beet processing factory what his biggest non-process related problem was chances are ex cellent that he would tell you ODORS These odors which range from musty smells to hazardous gases are a nuisance to the community and to the factory personnel The problem is severe enough that by our best estimate the US beet-sugar processing industry spends at least $450000000 annually on odor masking ag ents pH control reagents foam control bioaugmentation settling aids and other quick fix methods to minimize the odor problem This significant investmen t rarely if ever produces a favorable return and results are typically based on anecdotal observations rather than quantifiable data Nalco u tilizing an extensive experience in ra w wa ter and waste water treatment techniques has enabled clients in other industries to reuse and recycle wastewater successfully This has helped our clients eliminate the roo t cause of fresh water supply and wastewater management problems Recently Nalco has used some of these resources to assist some of our sugar beet processing clients in Minnesota and Nor th Dakota to identify and eliminate the Root Cause of the sugar beet factory odor problem This paper discusses the basic concepts and results of work in progress

BACKGROUND

Most of the odor producin g compounds in the factory w astewater treatment loop result f rom the uncontrolled anaerobic biological decomposition of the organic materials removed from the beet transport w ater system The mud from the fl ume wate r clari f ier is typically impounded in an open lagoon system Here the solids are allowed to settle out and t he supernate water is removed to replenish the beet transport (flume) water 01 is sent to the factory wastewater treatment system The volume of mud va ries quite widely from factory to factory based on the harvest soil condition of the incoming beets t he amount of lime added to control transport water pH the operational practices of t he f lume water clarifier and any mechanical dewateringlthickening capabilities

PREPARED FOR

ASSBT ANAHEIM CA

MARCH 5 1993

133

INTRODUCTION

If you were to ask the Operations Manager of a typical Northern United States sugar beet processing factory what his biggest non-process related problem was chances are ex cellent that he would tell you ODORS These odors which range from musty smells to hazardous gases are a nuisance to the community and to the factory personnel The problem is severe enough that by our best estimate the US beet-sugar processing industry spends at least $450000000 annually on odor masking ag ents pH control reagents foam control bioaugmentation settling aids and other quick fix methods to minimize the odor problem This significant investmen t rarely if ever produces a favorable return and results are typically based on anecdotal observations rather than quantifiable data Nalco u tilizing an extensive experience in ra w wa ter and waste water treatment techniques has enabled clients in other industries to reuse and recycle wastewater successfully This has helped our clients eliminate the roo t cause of fresh water supply and wastewater management problems Recently Nalco has used some of these resources to assist some of our sugar beet processing clients in Minnesota and Nor th Dakota to identify and eliminate the Root Cause of the sugar beet factory odor problem This paper discusses the basic concepts and results of work in progress

BACKGROUND

Most of the odor producin g compounds in the factory w astewater treatment loop result f rom the uncontrolled anaerobic biological decomposition of the organic materials removed from the beet transport w ater system The mud from the fl ume wate r clari f ier is typically impounded in an open lagoon system Here the solids are allowed to settle out and t he supernate water is removed to replenish the beet transport (flume) water 01 is sent to the factory wastewater treatment system The volume of mud va ries quite widely from factory to factory based on the harvest soil condition of the incoming beets t he amount of lime added to control transport water pH the operational practices of t he f lume water clarifier and any mechanical dewateringlthickening capabilities

PREPARED FOR

ASSBT ANAHEIM CA

MARCH 5 1993

133

The flume water system is designed to transport the beets f rom post-harvest storage locations into the factory while simultaneously removing field dirt rocks and other trash t hat might adversely affect slicing and diffusion Flume water also may receive small waste streams from the factory such as furnace ash sluice water excess condensates and cooling waters The most common method of flume w ater treatment is to maintain the pH in the range of 110 - 120 using lime It is well documented that maintaining this high pH retards acid forming bacterial activity The lime addition also promotes precipitation of magnesium hydroxide if the pH is above 105 (Ca(OH)2 + MgC03 = Mg(OHb + CaC0 3 ) and calcium carbonate (Ca(OH) 2 + Ca(HC03)2 = 2CaC03 + H20) if the pH is below 100 Operators generally observe that a cleaner flume water clarifier effluent can result from the co-precipitation and weighting action of the additional suspended solids contributed by the lime Some factories have chosen not to pH adjust their flume water systems accepting the corrosion damage H2S gas and sugar loss of the acid producing bacteria in the flume water as a normal cost of operation

Since 1986 Nalco has been involved with our clients in Minnesota and North Dakota to help reduce the volume of mud coming out of the mechanical flume water clari f iers We took the normal route for a specialty chemical company and used organic polymers to aid in thickening of the mUd Initial results were generally encouraging with volume reductions of 40-60 but performance was not consistent Statistical analyses showed us that their were special causes of variation that need ed to be eliminated before the mud volume reduction process could be considered statistically capable

PREPARED FOR

ASSST ANAHEIM CA

MARCH 5 1993

134

Bench-scale studies showed a significant correlation between mud dewaterability and pH In general mud pH above 115 or below 80 did not seWe or dewater well(Figures 1 amp 2) These findings are consistent with our knowledge of waste sludge from both cold-lime-softening municipal water treatment plants and pulp and paper mill green liquor clarifiers In municipal water treatment lime is added to both clarify and reduce the level of calcium and magnesium in the drinking water This makes it softer and easier t o w ash and c lean with The basic process is similar to the juice purification process in the sugar beet factory The water-holding (hyd rous) voluminous nature of the magnesium hydroxide precipitates in this high pH slud ge makes it very difficult to dewater When the pH falls to below 100 t he primary precipitate is calcium carbonate w hich is about 18th the size of magnesium hydrox ide and t raps less water One other operational concern with lime addition is that w hen the pH drops below 11 0 it is typically ve ry difficult to get the pH back up due to the increased acid-forming bioactivity in t he flumeshywater As the pH falls the factory may also ex perience severe scale formation on screens in piping and in c irculating pumps Th is increases the maintenance costs and potentia lly can slow slice rates

The typica l root cause fo r fl ume w ater with a low pH is acid-forming bacteria actively decomposing high levels of soluble organics in the flume water from

degraded or damaged beets The acid-forming bacteria generate gases as a w aste product that accelerate the foaming tendency of the flume water and further hinder the settling of the mud and soils in the clarifier The biological degradation of the soluble organics in the flume also may lead to the formation of natural organic anionic charge reinforcing dispersant compounds These compounds may hinder the f locculation and settleability of the nearly colloidal fine soil particles In the early years of water treatment chemical additives natural dispersant compounds found in todays typical beet flumes such as dextran cellulose lignin and pectin were used to prevent mineral scale and si lt fouling Operating at low pHs changes the stabilit y of the flu me w ater to a corrosive nature This leads t o co rros ion of metal and concrete components of the beet t ransport system Increased requirements to slice more beets faster make the significant maintenance t ime and expense to repair the flume even less attractive Excessive fermentation gas production may also increase the exposure of operating personnel to health and explosion risks from hydrogen sulfide gas

PREPARED FOR ASSBT

ANAHEIM CA MARCH 5 1993

135

The recent trend toward longer processing campaigns and virtuall y year-round molasses desugarization or other by-product operations results in new challenges to wastewater processing Pondlagoon systems t hat could normally be processed and emptied during t he intercampaign period are now fil ling up Irrigation practices are bei ng closely scrutinized by regulatory agencies Land for more ponds or irrigation is either not available or is too high priced The relative strength of the wastew ater organic load has increased pushing the factory-specific wastewater treatment systems to their limits leaving no room for slowdowns or upset recovery Local regulatory agencies are demanding aggressive action to abate odor complaints and meet ever tighter discharge water quality requirements The past procedure of adding fresh potable quality water to a sick flume is typically not feasible due to increased cost or lack of availability coupled with the lack of pond space to store the added gallons The root cause focus keeps coming back to reuse and recycle of flume water

THE TROUBLE WITH LIME

Acid production is a natural continuous process in stored sugar beet processing The rate and volume of acid produced is a factor of stored beet conditions and flume-water acid -forming bacteria activity To maintain an acceptable flume water pH these acids must be neutralized by bicarbonate carbonate or hydroxide alkalinity The practice of adding lime to control the pH of recycled beet transport water is actually counter-productive It reduces the alkalinity in the water as it precipitates the calcium and magnesium associated with carbonate and hydroxide alkalinity species respectively Removal of alkalinity red uces the buffering capability of the water making it much more susceptible to low pH excursions As you can see from the following equations in the typical beet transport system each pound of lime you add to the flume water reduces the bicarbonate alkalinity by 2 pounds by forming calcium carbonate from the carbon dioxide and bicarbonate alkalinity (Equ8tion 1) Taking the flume-water pH up to 110 + means you will also precipitate magnesium hydroxide which also results in a one for one alkalinity reduction (Equtrtion 2) The alkalinity remaining at a pH above 110 is exclusively in the hydroxide form which does not exist below a pH of 102 explaining the difficulty encountered maintaining the pH between 5 and lOusing only lime

PREPARED FOR

ASSBT ANAHEIM CA

MARCH 5 1993

13 6

SUMMARY

It appears to be technically and economically feasible to reduce or eliminate the use of lime in the t reatment of beet transport water The expected benefits of this approach are

1 Reduced sludge volume in mud ponds- Less solid waste to handle and dispose of Room to expand to accommodate longer campaigns and intercampaign bishyproduct runs

2 Improved dewaterability of slud ge in mud ponds - Recover recycle water faster Red uce the mud pond area Enable faster turn around on the ponds

3 Reduced odor complaints- Organics that cause odors as they degrade can be leached out of the mud and treated in a contro lled manner rather than w aiting for nature to take its course du ring the warm weat her months

4 Improved stabili ty of the flume-water- Reduced potential for corrosion andor scale formation t hat can cost you production or maintenance dollars

5 Ability to reuse wastewater in the flume- Reduced freshwater consumption High dissolved solids in recycle w ater will also equa lize the osmotic pressure betw een the flume w ater and t he beets reducing the tendency of sugar to diffuse out of t he flumed beets Reduced inventory of wastewater to treat and discharge irrigate or impound

6 Reduce or eliminate flume-water foaming - Red uced antifoam consumption Improved sett ling in flume-water clarifier

Nalco would like to than k t he operatio n s a nd management personnel of American Crystal Sugar factorie s in Drayton ND East Grand Forks MN Crookston MN Hillsboro ND and Moorhead MN f or their a ssistance in generating the data for t his paper These professiona l s have demonstrated t h e initiative t o achieve c onti nuous improvement in all aspects o f beet s ugar processi n g

PREPARED FOR

ASSBT ANAHEIM CA

MARCH 5 1993

137

4shy

BEET TRANSPORT WATER DE WATERABILITY OF SLUDGE

FILTE R LEAF TEST v

1250 iL SA~P LE OF CLARIFIER UKDERFLOW I FIGURE 1

BEET TRANSPORT WATER DEWATERABILITY OF SLUDGE

FILTER LEAF TEST v

pH UNITS

250 ML SAMPLE OF CLARIFIER CKDERFLOW 5 LBS POLYMERDRY TON SLUDGE FIGURE 2

6 4 111111111111111 ~ 7 5 llllilllllllli lt~ ] 74 IIIII)IIIIII ~ ] 77 11111111111111 ~ 8 2 Ililllllllllll ~ 9 4- 1111lllllill ~

106 11(1111 ~ I 112 IIIIIII~ ~

o 50 100 150 200 250 300 ML OF WATER

~ 10 MIN

0]8 MIN

6 MIN

~ 4shy MIN

bullbullbullbull 2 MIK

1 60 SEC

30 SEC

pH UNrTS

B 2 94

10 11

IIIIIIIIII ~ IIIIIIIII ~ ] IIIIIIIIII ~ ] 11111111 ~ IIIIIIIIIIli ~ m

Ii -~

I l ll l O -IOiI

1111111111 ~ i

1

100 150 200 250 ML OF WATER

o 50

i

88110 ~r I

ITl e MIN

6 MIN

MIN

2 MIK

11 60 SEC

30 SEC

138

200

180

160

E 8 140

en c o - 120 0gt 2 0

~ 100 co o (5 80

u c

8 60

40

20

o 7 10 11 12 13 14

pH

-

I

n

~ ~

~

8 9

-

Concentration Of ~~ Calcium Ion In

Equilibrium With CaC03

Concentration Of -

r

J Magnesium Ion In Equilibrium With

Mg(OH)2 -

Figure 3 - Equilibrium concentration of calcium and magnesium ions plotted against pH -139shy

BEET TRANSP ORT WATER SOFTENING EFFECT ON SLUDGE PRODUCTION

USING LIME ONLY

i FLUME pH

I

I i

64 I I I I

7 5

74 $ l~77 -

82 shy94 ~~

10 6 ~~ 112 -~

0 10 20 30 40 50 60 70

TONSDAYI shy

l IDO GPM FLOW TO POID ALL SLUDGE IS DRY WEIGHT BASIS

MG SLUDGE

CA SLUDGE

FIGURE 4

I

L

BEET TRANSPORT WATER SOFfENING EFFECT ON SLUDGE PRODUCTION

USING SODIUM HYDROXIDE ~==============================~------~i - ~

pH UNITS

6 4175 7 4

Ii MG SLUDGE ~9 4~ CA SLUDGEbull

106 11 2

o 5

I TOrS OF SLUDGE I

1 1

~f gt i i 1 1

I i

bull I

10 15 20 25 30

~=======================1----~--_ 1100 GPM FLOW TO POND ALL SLUDGE DRY WEIGHT BASIS FIGURE 5

140

~------------------------------~

BEET TRANSPORT WATER SOFTENING EFFECT ON FLUME pH

USING LIME ONLY ~____~~____________________ v~

FLUME pH I

I 11r-~-~-U-ME--U-SE-D-)

l i

0 10 20 30 40 50 60 TONSDAY

i

11100 GPM FLO W TO PONDI FIGURE 6

BEET TRANSP ORT WATER SOFTENING EFFECT ON pH

SODIUM HYDROXIDE DAILY USAGE ~_____ __ __ ~ _=- ________ ________________ _ __ _____ -Y

~- - ---- _ __- _ ------- (

Ph UNITS

64 I 7 5~ J 7 4~ 77~ 8 2~~ 94~~ 106~~~

I 11 2~~~ I

I o 5 10 15 20 j LBSDAY (OOOS)

~l================-______________~) 11100 GPM FLOW TO POND I FIGU RE 7

141

Bench-scale studies showed a significant correlation between mud dewaterability and pH In general mud pH above 115 or below 80 did not seWe or dewater well(Figures 1 amp 2) These findings are consistent with our knowledge of waste sludge from both cold-lime-softening municipal water treatment plants and pulp and paper mill green liquor clarifiers In municipal water treatment lime is added to both clarify and reduce the level of calcium and magnesium in the drinking water This makes it softer and easier t o w ash and c lean with The basic process is similar to the juice purification process in the sugar beet factory The water-holding (hyd rous) voluminous nature of the magnesium hydroxide precipitates in this high pH slud ge makes it very difficult to dewater When the pH falls to below 100 t he primary precipitate is calcium carbonate w hich is about 18th the size of magnesium hydrox ide and t raps less water One other operational concern with lime addition is that w hen the pH drops below 11 0 it is typically ve ry difficult to get the pH back up due to the increased acid-forming bioactivity in t he flumeshywater As the pH falls the factory may also ex perience severe scale formation on screens in piping and in c irculating pumps Th is increases the maintenance costs and potentia lly can slow slice rates

The typica l root cause fo r fl ume w ater with a low pH is acid-forming bacteria actively decomposing high levels of soluble organics in the flume water from

degraded or damaged beets The acid-forming bacteria generate gases as a w aste product that accelerate the foaming tendency of the flume water and further hinder the settling of the mud and soils in the clarifier The biological degradation of the soluble organics in the flume also may lead to the formation of natural organic anionic charge reinforcing dispersant compounds These compounds may hinder the f locculation and settleability of the nearly colloidal fine soil particles In the early years of water treatment chemical additives natural dispersant compounds found in todays typical beet flumes such as dextran cellulose lignin and pectin were used to prevent mineral scale and si lt fouling Operating at low pHs changes the stabilit y of the flu me w ater to a corrosive nature This leads t o co rros ion of metal and concrete components of the beet t ransport system Increased requirements to slice more beets faster make the significant maintenance t ime and expense to repair the flume even less attractive Excessive fermentation gas production may also increase the exposure of operating personnel to health and explosion risks from hydrogen sulfide gas

PREPARED FOR ASSBT

ANAHEIM CA MARCH 5 1993

135

The recent trend toward longer processing campaigns and virtuall y year-round molasses desugarization or other by-product operations results in new challenges to wastewater processing Pondlagoon systems t hat could normally be processed and emptied during t he intercampaign period are now fil ling up Irrigation practices are bei ng closely scrutinized by regulatory agencies Land for more ponds or irrigation is either not available or is too high priced The relative strength of the wastew ater organic load has increased pushing the factory-specific wastewater treatment systems to their limits leaving no room for slowdowns or upset recovery Local regulatory agencies are demanding aggressive action to abate odor complaints and meet ever tighter discharge water quality requirements The past procedure of adding fresh potable quality water to a sick flume is typically not feasible due to increased cost or lack of availability coupled with the lack of pond space to store the added gallons The root cause focus keeps coming back to reuse and recycle of flume water

THE TROUBLE WITH LIME

Acid production is a natural continuous process in stored sugar beet processing The rate and volume of acid produced is a factor of stored beet conditions and flume-water acid -forming bacteria activity To maintain an acceptable flume water pH these acids must be neutralized by bicarbonate carbonate or hydroxide alkalinity The practice of adding lime to control the pH of recycled beet transport water is actually counter-productive It reduces the alkalinity in the water as it precipitates the calcium and magnesium associated with carbonate and hydroxide alkalinity species respectively Removal of alkalinity red uces the buffering capability of the water making it much more susceptible to low pH excursions As you can see from the following equations in the typical beet transport system each pound of lime you add to the flume water reduces the bicarbonate alkalinity by 2 pounds by forming calcium carbonate from the carbon dioxide and bicarbonate alkalinity (Equ8tion 1) Taking the flume-water pH up to 110 + means you will also precipitate magnesium hydroxide which also results in a one for one alkalinity reduction (Equtrtion 2) The alkalinity remaining at a pH above 110 is exclusively in the hydroxide form which does not exist below a pH of 102 explaining the difficulty encountered maintaining the pH between 5 and lOusing only lime

PREPARED FOR

ASSBT ANAHEIM CA

MARCH 5 1993

13 6

SUMMARY

It appears to be technically and economically feasible to reduce or eliminate the use of lime in the t reatment of beet transport water The expected benefits of this approach are

1 Reduced sludge volume in mud ponds- Less solid waste to handle and dispose of Room to expand to accommodate longer campaigns and intercampaign bishyproduct runs

2 Improved dewaterability of slud ge in mud ponds - Recover recycle water faster Red uce the mud pond area Enable faster turn around on the ponds

3 Reduced odor complaints- Organics that cause odors as they degrade can be leached out of the mud and treated in a contro lled manner rather than w aiting for nature to take its course du ring the warm weat her months

4 Improved stabili ty of the flume-water- Reduced potential for corrosion andor scale formation t hat can cost you production or maintenance dollars

5 Ability to reuse wastewater in the flume- Reduced freshwater consumption High dissolved solids in recycle w ater will also equa lize the osmotic pressure betw een the flume w ater and t he beets reducing the tendency of sugar to diffuse out of t he flumed beets Reduced inventory of wastewater to treat and discharge irrigate or impound

6 Reduce or eliminate flume-water foaming - Red uced antifoam consumption Improved sett ling in flume-water clarifier

Nalco would like to than k t he operatio n s a nd management personnel of American Crystal Sugar factorie s in Drayton ND East Grand Forks MN Crookston MN Hillsboro ND and Moorhead MN f or their a ssistance in generating the data for t his paper These professiona l s have demonstrated t h e initiative t o achieve c onti nuous improvement in all aspects o f beet s ugar processi n g

PREPARED FOR

ASSBT ANAHEIM CA

MARCH 5 1993

137

4shy

BEET TRANSPORT WATER DE WATERABILITY OF SLUDGE

FILTE R LEAF TEST v

1250 iL SA~P LE OF CLARIFIER UKDERFLOW I FIGURE 1

BEET TRANSPORT WATER DEWATERABILITY OF SLUDGE

FILTER LEAF TEST v

pH UNITS

250 ML SAMPLE OF CLARIFIER CKDERFLOW 5 LBS POLYMERDRY TON SLUDGE FIGURE 2

6 4 111111111111111 ~ 7 5 llllilllllllli lt~ ] 74 IIIII)IIIIII ~ ] 77 11111111111111 ~ 8 2 Ililllllllllll ~ 9 4- 1111lllllill ~

106 11(1111 ~ I 112 IIIIIII~ ~

o 50 100 150 200 250 300 ML OF WATER

~ 10 MIN

0]8 MIN

6 MIN

~ 4shy MIN

bullbullbullbull 2 MIK

1 60 SEC

30 SEC

pH UNrTS

B 2 94

10 11

IIIIIIIIII ~ IIIIIIIII ~ ] IIIIIIIIII ~ ] 11111111 ~ IIIIIIIIIIli ~ m

Ii -~

I l ll l O -IOiI

1111111111 ~ i

1

100 150 200 250 ML OF WATER

o 50

i

88110 ~r I

ITl e MIN

6 MIN

MIN

2 MIK

11 60 SEC

30 SEC

138

200

180

160

E 8 140

en c o - 120 0gt 2 0

~ 100 co o (5 80

u c

8 60

40

20

o 7 10 11 12 13 14

pH

-

I

n

~ ~

~

8 9

-

Concentration Of ~~ Calcium Ion In

Equilibrium With CaC03

Concentration Of -

r

J Magnesium Ion In Equilibrium With

Mg(OH)2 -

Figure 3 - Equilibrium concentration of calcium and magnesium ions plotted against pH -139shy

BEET TRANSP ORT WATER SOFTENING EFFECT ON SLUDGE PRODUCTION

USING LIME ONLY

i FLUME pH

I

I i

64 I I I I

7 5

74 $ l~77 -

82 shy94 ~~

10 6 ~~ 112 -~

0 10 20 30 40 50 60 70

TONSDAYI shy

l IDO GPM FLOW TO POID ALL SLUDGE IS DRY WEIGHT BASIS

MG SLUDGE

CA SLUDGE

FIGURE 4

I

L

BEET TRANSPORT WATER SOFfENING EFFECT ON SLUDGE PRODUCTION

USING SODIUM HYDROXIDE ~==============================~------~i - ~

pH UNITS

6 4175 7 4

Ii MG SLUDGE ~9 4~ CA SLUDGEbull

106 11 2

o 5

I TOrS OF SLUDGE I

1 1

~f gt i i 1 1

I i

bull I

10 15 20 25 30

~=======================1----~--_ 1100 GPM FLOW TO POND ALL SLUDGE DRY WEIGHT BASIS FIGURE 5

140

~------------------------------~

BEET TRANSPORT WATER SOFTENING EFFECT ON FLUME pH

USING LIME ONLY ~____~~____________________ v~

FLUME pH I

I 11r-~-~-U-ME--U-SE-D-)

l i

0 10 20 30 40 50 60 TONSDAY

i

11100 GPM FLO W TO PONDI FIGURE 6

BEET TRANSP ORT WATER SOFTENING EFFECT ON pH

SODIUM HYDROXIDE DAILY USAGE ~_____ __ __ ~ _=- ________ ________________ _ __ _____ -Y

~- - ---- _ __- _ ------- (

Ph UNITS

64 I 7 5~ J 7 4~ 77~ 8 2~~ 94~~ 106~~~

I 11 2~~~ I

I o 5 10 15 20 j LBSDAY (OOOS)

~l================-______________~) 11100 GPM FLOW TO POND I FIGU RE 7

141

The recent trend toward longer processing campaigns and virtuall y year-round molasses desugarization or other by-product operations results in new challenges to wastewater processing Pondlagoon systems t hat could normally be processed and emptied during t he intercampaign period are now fil ling up Irrigation practices are bei ng closely scrutinized by regulatory agencies Land for more ponds or irrigation is either not available or is too high priced The relative strength of the wastew ater organic load has increased pushing the factory-specific wastewater treatment systems to their limits leaving no room for slowdowns or upset recovery Local regulatory agencies are demanding aggressive action to abate odor complaints and meet ever tighter discharge water quality requirements The past procedure of adding fresh potable quality water to a sick flume is typically not feasible due to increased cost or lack of availability coupled with the lack of pond space to store the added gallons The root cause focus keeps coming back to reuse and recycle of flume water

THE TROUBLE WITH LIME

Acid production is a natural continuous process in stored sugar beet processing The rate and volume of acid produced is a factor of stored beet conditions and flume-water acid -forming bacteria activity To maintain an acceptable flume water pH these acids must be neutralized by bicarbonate carbonate or hydroxide alkalinity The practice of adding lime to control the pH of recycled beet transport water is actually counter-productive It reduces the alkalinity in the water as it precipitates the calcium and magnesium associated with carbonate and hydroxide alkalinity species respectively Removal of alkalinity red uces the buffering capability of the water making it much more susceptible to low pH excursions As you can see from the following equations in the typical beet transport system each pound of lime you add to the flume water reduces the bicarbonate alkalinity by 2 pounds by forming calcium carbonate from the carbon dioxide and bicarbonate alkalinity (Equ8tion 1) Taking the flume-water pH up to 110 + means you will also precipitate magnesium hydroxide which also results in a one for one alkalinity reduction (Equtrtion 2) The alkalinity remaining at a pH above 110 is exclusively in the hydroxide form which does not exist below a pH of 102 explaining the difficulty encountered maintaining the pH between 5 and lOusing only lime

PREPARED FOR

ASSBT ANAHEIM CA

MARCH 5 1993

13 6

SUMMARY

It appears to be technically and economically feasible to reduce or eliminate the use of lime in the t reatment of beet transport water The expected benefits of this approach are

1 Reduced sludge volume in mud ponds- Less solid waste to handle and dispose of Room to expand to accommodate longer campaigns and intercampaign bishyproduct runs

2 Improved dewaterability of slud ge in mud ponds - Recover recycle water faster Red uce the mud pond area Enable faster turn around on the ponds

3 Reduced odor complaints- Organics that cause odors as they degrade can be leached out of the mud and treated in a contro lled manner rather than w aiting for nature to take its course du ring the warm weat her months

4 Improved stabili ty of the flume-water- Reduced potential for corrosion andor scale formation t hat can cost you production or maintenance dollars

5 Ability to reuse wastewater in the flume- Reduced freshwater consumption High dissolved solids in recycle w ater will also equa lize the osmotic pressure betw een the flume w ater and t he beets reducing the tendency of sugar to diffuse out of t he flumed beets Reduced inventory of wastewater to treat and discharge irrigate or impound

6 Reduce or eliminate flume-water foaming - Red uced antifoam consumption Improved sett ling in flume-water clarifier

Nalco would like to than k t he operatio n s a nd management personnel of American Crystal Sugar factorie s in Drayton ND East Grand Forks MN Crookston MN Hillsboro ND and Moorhead MN f or their a ssistance in generating the data for t his paper These professiona l s have demonstrated t h e initiative t o achieve c onti nuous improvement in all aspects o f beet s ugar processi n g

PREPARED FOR

ASSBT ANAHEIM CA

MARCH 5 1993

137

4shy

BEET TRANSPORT WATER DE WATERABILITY OF SLUDGE

FILTE R LEAF TEST v

1250 iL SA~P LE OF CLARIFIER UKDERFLOW I FIGURE 1

BEET TRANSPORT WATER DEWATERABILITY OF SLUDGE

FILTER LEAF TEST v

pH UNITS

250 ML SAMPLE OF CLARIFIER CKDERFLOW 5 LBS POLYMERDRY TON SLUDGE FIGURE 2

6 4 111111111111111 ~ 7 5 llllilllllllli lt~ ] 74 IIIII)IIIIII ~ ] 77 11111111111111 ~ 8 2 Ililllllllllll ~ 9 4- 1111lllllill ~

106 11(1111 ~ I 112 IIIIIII~ ~

o 50 100 150 200 250 300 ML OF WATER

~ 10 MIN

0]8 MIN

6 MIN

~ 4shy MIN

bullbullbullbull 2 MIK

1 60 SEC

30 SEC

pH UNrTS

B 2 94

10 11

IIIIIIIIII ~ IIIIIIIII ~ ] IIIIIIIIII ~ ] 11111111 ~ IIIIIIIIIIli ~ m

Ii -~

I l ll l O -IOiI

1111111111 ~ i

1

100 150 200 250 ML OF WATER

o 50

i

88110 ~r I

ITl e MIN

6 MIN

MIN

2 MIK

11 60 SEC

30 SEC

138

200

180

160

E 8 140

en c o - 120 0gt 2 0

~ 100 co o (5 80

u c

8 60

40

20

o 7 10 11 12 13 14

pH

-

I

n

~ ~

~

8 9

-

Concentration Of ~~ Calcium Ion In

Equilibrium With CaC03

Concentration Of -

r

J Magnesium Ion In Equilibrium With

Mg(OH)2 -

Figure 3 - Equilibrium concentration of calcium and magnesium ions plotted against pH -139shy

BEET TRANSP ORT WATER SOFTENING EFFECT ON SLUDGE PRODUCTION

USING LIME ONLY

i FLUME pH

I

I i

64 I I I I

7 5

74 $ l~77 -

82 shy94 ~~

10 6 ~~ 112 -~

0 10 20 30 40 50 60 70

TONSDAYI shy

l IDO GPM FLOW TO POID ALL SLUDGE IS DRY WEIGHT BASIS

MG SLUDGE

CA SLUDGE

FIGURE 4

I

L

BEET TRANSPORT WATER SOFfENING EFFECT ON SLUDGE PRODUCTION

USING SODIUM HYDROXIDE ~==============================~------~i - ~

pH UNITS

6 4175 7 4

Ii MG SLUDGE ~9 4~ CA SLUDGEbull

106 11 2

o 5

I TOrS OF SLUDGE I

1 1

~f gt i i 1 1

I i

bull I

10 15 20 25 30

~=======================1----~--_ 1100 GPM FLOW TO POND ALL SLUDGE DRY WEIGHT BASIS FIGURE 5

140

~------------------------------~

BEET TRANSPORT WATER SOFTENING EFFECT ON FLUME pH

USING LIME ONLY ~____~~____________________ v~

FLUME pH I

I 11r-~-~-U-ME--U-SE-D-)

l i

0 10 20 30 40 50 60 TONSDAY

i

11100 GPM FLO W TO PONDI FIGURE 6

BEET TRANSP ORT WATER SOFTENING EFFECT ON pH

SODIUM HYDROXIDE DAILY USAGE ~_____ __ __ ~ _=- ________ ________________ _ __ _____ -Y

~- - ---- _ __- _ ------- (

Ph UNITS

64 I 7 5~ J 7 4~ 77~ 8 2~~ 94~~ 106~~~

I 11 2~~~ I

I o 5 10 15 20 j LBSDAY (OOOS)

~l================-______________~) 11100 GPM FLOW TO POND I FIGU RE 7

141

SUMMARY

It appears to be technically and economically feasible to reduce or eliminate the use of lime in the t reatment of beet transport water The expected benefits of this approach are

1 Reduced sludge volume in mud ponds- Less solid waste to handle and dispose of Room to expand to accommodate longer campaigns and intercampaign bishyproduct runs

2 Improved dewaterability of slud ge in mud ponds - Recover recycle water faster Red uce the mud pond area Enable faster turn around on the ponds

3 Reduced odor complaints- Organics that cause odors as they degrade can be leached out of the mud and treated in a contro lled manner rather than w aiting for nature to take its course du ring the warm weat her months

4 Improved stabili ty of the flume-water- Reduced potential for corrosion andor scale formation t hat can cost you production or maintenance dollars

5 Ability to reuse wastewater in the flume- Reduced freshwater consumption High dissolved solids in recycle w ater will also equa lize the osmotic pressure betw een the flume w ater and t he beets reducing the tendency of sugar to diffuse out of t he flumed beets Reduced inventory of wastewater to treat and discharge irrigate or impound

6 Reduce or eliminate flume-water foaming - Red uced antifoam consumption Improved sett ling in flume-water clarifier

Nalco would like to than k t he operatio n s a nd management personnel of American Crystal Sugar factorie s in Drayton ND East Grand Forks MN Crookston MN Hillsboro ND and Moorhead MN f or their a ssistance in generating the data for t his paper These professiona l s have demonstrated t h e initiative t o achieve c onti nuous improvement in all aspects o f beet s ugar processi n g

PREPARED FOR

ASSBT ANAHEIM CA

MARCH 5 1993

137

4shy

BEET TRANSPORT WATER DE WATERABILITY OF SLUDGE

FILTE R LEAF TEST v

1250 iL SA~P LE OF CLARIFIER UKDERFLOW I FIGURE 1

BEET TRANSPORT WATER DEWATERABILITY OF SLUDGE

FILTER LEAF TEST v

pH UNITS

250 ML SAMPLE OF CLARIFIER CKDERFLOW 5 LBS POLYMERDRY TON SLUDGE FIGURE 2

6 4 111111111111111 ~ 7 5 llllilllllllli lt~ ] 74 IIIII)IIIIII ~ ] 77 11111111111111 ~ 8 2 Ililllllllllll ~ 9 4- 1111lllllill ~

106 11(1111 ~ I 112 IIIIIII~ ~

o 50 100 150 200 250 300 ML OF WATER

~ 10 MIN

0]8 MIN

6 MIN

~ 4shy MIN

bullbullbullbull 2 MIK

1 60 SEC

30 SEC

pH UNrTS

B 2 94

10 11

IIIIIIIIII ~ IIIIIIIII ~ ] IIIIIIIIII ~ ] 11111111 ~ IIIIIIIIIIli ~ m

Ii -~

I l ll l O -IOiI

1111111111 ~ i

1

100 150 200 250 ML OF WATER

o 50

i

88110 ~r I

ITl e MIN

6 MIN

MIN

2 MIK

11 60 SEC

30 SEC

138

200

180

160

E 8 140

en c o - 120 0gt 2 0

~ 100 co o (5 80

u c

8 60

40

20

o 7 10 11 12 13 14

pH

-

I

n

~ ~

~

8 9

-

Concentration Of ~~ Calcium Ion In

Equilibrium With CaC03

Concentration Of -

r

J Magnesium Ion In Equilibrium With

Mg(OH)2 -

Figure 3 - Equilibrium concentration of calcium and magnesium ions plotted against pH -139shy

BEET TRANSP ORT WATER SOFTENING EFFECT ON SLUDGE PRODUCTION

USING LIME ONLY

i FLUME pH

I

I i

64 I I I I

7 5

74 $ l~77 -

82 shy94 ~~

10 6 ~~ 112 -~

0 10 20 30 40 50 60 70

TONSDAYI shy

l IDO GPM FLOW TO POID ALL SLUDGE IS DRY WEIGHT BASIS

MG SLUDGE

CA SLUDGE

FIGURE 4

I

L

BEET TRANSPORT WATER SOFfENING EFFECT ON SLUDGE PRODUCTION

USING SODIUM HYDROXIDE ~==============================~------~i - ~

pH UNITS

6 4175 7 4

Ii MG SLUDGE ~9 4~ CA SLUDGEbull

106 11 2

o 5

I TOrS OF SLUDGE I

1 1

~f gt i i 1 1

I i

bull I

10 15 20 25 30

~=======================1----~--_ 1100 GPM FLOW TO POND ALL SLUDGE DRY WEIGHT BASIS FIGURE 5

140

~------------------------------~

BEET TRANSPORT WATER SOFTENING EFFECT ON FLUME pH

USING LIME ONLY ~____~~____________________ v~

FLUME pH I

I 11r-~-~-U-ME--U-SE-D-)

l i

0 10 20 30 40 50 60 TONSDAY

i

11100 GPM FLO W TO PONDI FIGURE 6

BEET TRANSP ORT WATER SOFTENING EFFECT ON pH

SODIUM HYDROXIDE DAILY USAGE ~_____ __ __ ~ _=- ________ ________________ _ __ _____ -Y

~- - ---- _ __- _ ------- (

Ph UNITS

64 I 7 5~ J 7 4~ 77~ 8 2~~ 94~~ 106~~~

I 11 2~~~ I

I o 5 10 15 20 j LBSDAY (OOOS)

~l================-______________~) 11100 GPM FLOW TO POND I FIGU RE 7

141

4shy

BEET TRANSPORT WATER DE WATERABILITY OF SLUDGE

FILTE R LEAF TEST v

1250 iL SA~P LE OF CLARIFIER UKDERFLOW I FIGURE 1

BEET TRANSPORT WATER DEWATERABILITY OF SLUDGE

FILTER LEAF TEST v

pH UNITS

250 ML SAMPLE OF CLARIFIER CKDERFLOW 5 LBS POLYMERDRY TON SLUDGE FIGURE 2

6 4 111111111111111 ~ 7 5 llllilllllllli lt~ ] 74 IIIII)IIIIII ~ ] 77 11111111111111 ~ 8 2 Ililllllllllll ~ 9 4- 1111lllllill ~

106 11(1111 ~ I 112 IIIIIII~ ~

o 50 100 150 200 250 300 ML OF WATER

~ 10 MIN

0]8 MIN

6 MIN

~ 4shy MIN

bullbullbullbull 2 MIK

1 60 SEC

30 SEC

pH UNrTS

B 2 94

10 11

IIIIIIIIII ~ IIIIIIIII ~ ] IIIIIIIIII ~ ] 11111111 ~ IIIIIIIIIIli ~ m

Ii -~

I l ll l O -IOiI

1111111111 ~ i

1

100 150 200 250 ML OF WATER

o 50

i

88110 ~r I

ITl e MIN

6 MIN

MIN

2 MIK

11 60 SEC

30 SEC

138

200

180

160

E 8 140

en c o - 120 0gt 2 0

~ 100 co o (5 80

u c

8 60

40

20

o 7 10 11 12 13 14

pH

-

I

n

~ ~

~

8 9

-

Concentration Of ~~ Calcium Ion In

Equilibrium With CaC03

Concentration Of -

r

J Magnesium Ion In Equilibrium With

Mg(OH)2 -

Figure 3 - Equilibrium concentration of calcium and magnesium ions plotted against pH -139shy

BEET TRANSP ORT WATER SOFTENING EFFECT ON SLUDGE PRODUCTION

USING LIME ONLY

i FLUME pH

I

I i

64 I I I I

7 5

74 $ l~77 -

82 shy94 ~~

10 6 ~~ 112 -~

0 10 20 30 40 50 60 70

TONSDAYI shy

l IDO GPM FLOW TO POID ALL SLUDGE IS DRY WEIGHT BASIS

MG SLUDGE

CA SLUDGE

FIGURE 4

I

L

BEET TRANSPORT WATER SOFfENING EFFECT ON SLUDGE PRODUCTION

USING SODIUM HYDROXIDE ~==============================~------~i - ~

pH UNITS

6 4175 7 4

Ii MG SLUDGE ~9 4~ CA SLUDGEbull

106 11 2

o 5

I TOrS OF SLUDGE I

1 1

~f gt i i 1 1

I i

bull I

10 15 20 25 30

~=======================1----~--_ 1100 GPM FLOW TO POND ALL SLUDGE DRY WEIGHT BASIS FIGURE 5

140

~------------------------------~

BEET TRANSPORT WATER SOFTENING EFFECT ON FLUME pH

USING LIME ONLY ~____~~____________________ v~

FLUME pH I

I 11r-~-~-U-ME--U-SE-D-)

l i

0 10 20 30 40 50 60 TONSDAY

i

11100 GPM FLO W TO PONDI FIGURE 6

BEET TRANSP ORT WATER SOFTENING EFFECT ON pH

SODIUM HYDROXIDE DAILY USAGE ~_____ __ __ ~ _=- ________ ________________ _ __ _____ -Y

~- - ---- _ __- _ ------- (

Ph UNITS

64 I 7 5~ J 7 4~ 77~ 8 2~~ 94~~ 106~~~

I 11 2~~~ I

I o 5 10 15 20 j LBSDAY (OOOS)

~l================-______________~) 11100 GPM FLOW TO POND I FIGU RE 7

141

200

180

160

E 8 140

en c o - 120 0gt 2 0

~ 100 co o (5 80

u c

8 60

40

20

o 7 10 11 12 13 14

pH

-

I

n

~ ~

~

8 9

-

Concentration Of ~~ Calcium Ion In

Equilibrium With CaC03

Concentration Of -

r

J Magnesium Ion In Equilibrium With

Mg(OH)2 -

Figure 3 - Equilibrium concentration of calcium and magnesium ions plotted against pH -139shy

BEET TRANSP ORT WATER SOFTENING EFFECT ON SLUDGE PRODUCTION

USING LIME ONLY

i FLUME pH

I

I i

64 I I I I

7 5

74 $ l~77 -

82 shy94 ~~

10 6 ~~ 112 -~

0 10 20 30 40 50 60 70

TONSDAYI shy

l IDO GPM FLOW TO POID ALL SLUDGE IS DRY WEIGHT BASIS

MG SLUDGE

CA SLUDGE

FIGURE 4

I

L

BEET TRANSPORT WATER SOFfENING EFFECT ON SLUDGE PRODUCTION

USING SODIUM HYDROXIDE ~==============================~------~i - ~

pH UNITS

6 4175 7 4

Ii MG SLUDGE ~9 4~ CA SLUDGEbull

106 11 2

o 5

I TOrS OF SLUDGE I

1 1

~f gt i i 1 1

I i

bull I

10 15 20 25 30

~=======================1----~--_ 1100 GPM FLOW TO POND ALL SLUDGE DRY WEIGHT BASIS FIGURE 5

140

~------------------------------~

BEET TRANSPORT WATER SOFTENING EFFECT ON FLUME pH

USING LIME ONLY ~____~~____________________ v~

FLUME pH I

I 11r-~-~-U-ME--U-SE-D-)

l i

0 10 20 30 40 50 60 TONSDAY

i

11100 GPM FLO W TO PONDI FIGURE 6

BEET TRANSP ORT WATER SOFTENING EFFECT ON pH

SODIUM HYDROXIDE DAILY USAGE ~_____ __ __ ~ _=- ________ ________________ _ __ _____ -Y

~- - ---- _ __- _ ------- (

Ph UNITS

64 I 7 5~ J 7 4~ 77~ 8 2~~ 94~~ 106~~~

I 11 2~~~ I

I o 5 10 15 20 j LBSDAY (OOOS)

~l================-______________~) 11100 GPM FLOW TO POND I FIGU RE 7

141

BEET TRANSP ORT WATER SOFTENING EFFECT ON SLUDGE PRODUCTION

USING LIME ONLY

i FLUME pH

I

I i

64 I I I I

7 5

74 $ l~77 -

82 shy94 ~~

10 6 ~~ 112 -~

0 10 20 30 40 50 60 70

TONSDAYI shy

l IDO GPM FLOW TO POID ALL SLUDGE IS DRY WEIGHT BASIS

MG SLUDGE

CA SLUDGE

FIGURE 4

I

L

BEET TRANSPORT WATER SOFfENING EFFECT ON SLUDGE PRODUCTION

USING SODIUM HYDROXIDE ~==============================~------~i - ~

pH UNITS

6 4175 7 4

Ii MG SLUDGE ~9 4~ CA SLUDGEbull

106 11 2

o 5

I TOrS OF SLUDGE I

1 1

~f gt i i 1 1

I i

bull I

10 15 20 25 30

~=======================1----~--_ 1100 GPM FLOW TO POND ALL SLUDGE DRY WEIGHT BASIS FIGURE 5

140

~------------------------------~

BEET TRANSPORT WATER SOFTENING EFFECT ON FLUME pH

USING LIME ONLY ~____~~____________________ v~

FLUME pH I

I 11r-~-~-U-ME--U-SE-D-)

l i

0 10 20 30 40 50 60 TONSDAY

i

11100 GPM FLO W TO PONDI FIGURE 6

BEET TRANSP ORT WATER SOFTENING EFFECT ON pH

SODIUM HYDROXIDE DAILY USAGE ~_____ __ __ ~ _=- ________ ________________ _ __ _____ -Y

~- - ---- _ __- _ ------- (

Ph UNITS

64 I 7 5~ J 7 4~ 77~ 8 2~~ 94~~ 106~~~

I 11 2~~~ I

I o 5 10 15 20 j LBSDAY (OOOS)

~l================-______________~) 11100 GPM FLOW TO POND I FIGU RE 7

141

~------------------------------~

BEET TRANSPORT WATER SOFTENING EFFECT ON FLUME pH

USING LIME ONLY ~____~~____________________ v~

FLUME pH I

I 11r-~-~-U-ME--U-SE-D-)

l i

0 10 20 30 40 50 60 TONSDAY

i

11100 GPM FLO W TO PONDI FIGURE 6

BEET TRANSP ORT WATER SOFTENING EFFECT ON pH

SODIUM HYDROXIDE DAILY USAGE ~_____ __ __ ~ _=- ________ ________________ _ __ _____ -Y

~- - ---- _ __- _ ------- (

Ph UNITS

64 I 7 5~ J 7 4~ 77~ 8 2~~ 94~~ 106~~~

I 11 2~~~ I

I o 5 10 15 20 j LBSDAY (OOOS)

~l================-______________~) 11100 GPM FLOW TO POND I FIGU RE 7

141