WATER BALANCE & SOURCES OF WASTEWATER IN SUGAR MILL & REFINERY

Mr. Pastor Esmeris*

OBJECTIVES

• To instill water conservation among the participants.

• To present the water balance of a typical raw sugar factory and refinery.

• To discuss some considerations and recommendations for the efficient use of water in a sugar factory and present various applicable technologies.

Water Facts and Trivia:

• The over-all amount of water on earth has remained the same for about two billion years since the earth was formed.

• Water moves around the earth in a water cycle, consisting of evaporation, condensation, precipitation, infiltration and surface run-off.

• Of all the water on earth, only 2.5% is fresh water. Fresh water is either groundwater (0.5%) or readily accessible water in lakes, streams, rivers, etc. (0.01%)

• Over 90% of the world's supply of fresh water is in Antartica.

• Less than 1% of the water supply on earth can be used as drinking water.

• More than 2 billion people on earth do not have a safe supply of water.

• Two thirds of the water used in a home is used in the bathroom.

• Groundwater supplies serve about 80% of the population, whereas up to 4% of usable groundwater is already polluted.

• It takes 450 liters (120 gal.) of water to produce one egg.

• It takes 5,680 liters (1,500gal.) of water to process one barrel of beer.

• It takes 7,000 liters (1,850 gal.) of water to refine one barrel of crude oil.

• Conventionally, it takes 240-290 gal. (910-1,100 ltr.) of water to produce one Lkg of raw sugar; but if managed well, it will take only 1-10 gallons.

WATER MANAGEMENT

• Nature's management of water is based on recycling and this principle should form the basis of water management in the sugar industry.

• Roughly 40% of the water entering in the cane is surplus. The more energy efficient a factory is, the larger is the surplus water produced.

*/ Lopez Sugar Corp.

WATER MANAGEMENT

FACTS:

• Water, as a consumable in the process of sugar manufacture, has input costs.

• Sugarcane carries its own fuel and water to enable its processing.

• The process of sugar manufacture has no step wherein any liquid effluent must be generated and discharged.

• Pollution control laws now demand treatment of the plants effluents to strictly conform to the pollution tolerance limits before disposal.

• User fee or levy for the use of water will soon be imposed and this will increase input costs.

• Extra/ undesirable/ unnecessary use of water in the process results in: loss of heat energy; input of salts and impurities through raw water is partly responsible for scale formation in heat exchangers and melassegenic effects in exhaustion; extra energy input is required for pumping; loss of sugar by dissolution in water and generation of effluent.

Objectives of Water Management in the Sugar Factory

• Work the plant on cane water, i.e. water brought in through sugarcane.

• Minimize the use of ground/ surface water for the plant consumption.

• Eliminate/ minimize the generation of plant effluents.

SI. No.

Purification Process

Decolourisation Process

Estimated Water Consumption Cu. Mt. Per tonne of melt Process

(Fresh Water) Surface Conds.

(Sea Water) 1 Phosphatation & Ion Exchange 1.15 55- 65 2 Carbonatation & Ion Exchange 1.20 55- 65 3 Phosphatation & GAC Columns 0.16 55- 65 4 Carbonatation & GAC Columns 0.20 55- 65

WATER REQUIREMENT

• A conventional Raw Sugar Factory will require about 2.1 to 2.8 cu.m/ ton cane

• For a 5000 TCD factory this is about 440 cu.m. /hr. to 580 cu.m./hr.

• A 5000 TCD factory can manage to work with only 20 cu.m. /hr. water being put into its water system.

Table 2 Energy Usage

Cane sugar refining

(1) Steam to Raw Sugar Ratio (a) A typical refinery : 1.5 ton of steam to

one ton of raw sugar (b) A modern refinery : 0.55 ton of steam to

one ton of raw sugar

WATER REQUIREMENT OF A REFINERY TABLE 1

Estimated Water Consumption of Refinery in different arrangements

(2) Electricity

(a) A typical refinery : 75 kWh/ton raw sugar (b) A modern refinery : 4 5 kWh/ton raw sugar

(3) W a t e r

(a) (b)

A typical refinery : 150% of raw sugar A modern refinery : 50% of raw sugar

AL KHALEEJ SUGAR CO. U.A.E.

10 - Refinery Performance Comparison :

Year

Fuel kg / t

Water mt / t

Power kw hr / t

Steam kg / t

1997 77 382 121.64 938

1998 67 366 83.84 720

1999 47 245 72.588 597

2000 44 252 58.43 680

2001 48 281 61.38 635

2002 48 188 51.38 638

2003 47 179 58.186 645

2004 37 154 48.4 604

Definition of Terms

• Service water: raw river water used in the factory

• Filtered water: treated/potable water

• External water: water entering the factory, other than water contained in the cane (i.e. service or filtered water)

• Injection cooling system: factory condenser cooling water circuit

• Service cooling system: vacuum, crystallizer and bearing cooling water circuits

• Process water: any source of water produced by factory operations (i.e. excludes external water and water from the service cooling systems).

OVERALL MILL WATER BALANCE

SERVICE WATER

EVAPORATION

AT MILLS

FLASH SATURATED

BOILER GASES

CANE

EVAPORATION

FACTORY

BAGASSE BOILERS

WET ASH & SMUTS

MOLASSES

DRIFT LOSS

COOLING TOWERS/

POND

FILTER CAKE

SURPLUS

CONDENSATE

BOILER BLOWDOWN

SYSTEM

OVERFLOW

Over-all Balance

• A cane sugar mill process more water than sugar

• Roughly 40% of the water entering the cane is surplus which will find its way out of the mill in an effluent stream.

• Water enters the mill as constituents of sugarcane and part of it goes out in the bagasse.

Water Losses

• Water in the raw juice is lost through filter cake, pan and evaporator condensers, final molasses, sugar and boiler blowdowns.

• Other losses are in the cooling tower or spray pond overflow and drift loss (typically 5% of the water flow in the cooling system) and water in the boiler smuts.

Evaporation Losses

• Evaporation occurs from certain process streams and during juice flashing.

• Part of the water condensed in condensers will evaporate in the cooling towers or spray ponds to provide the evaporative cooling required. As much as 85% of the vapor condensed evaporates to provide the cooling.

• Evaporation in wet scrubbers is around 10% of the high-pressure steam generated.

Factory: Amatikulu

SUGAR FACTORY WATER BALANCE

WATER IN Tons/hr. WATER OUT Tons/hr

In Cane:

Tons cane/hr Fibre % cane Brix % cane

420 15.3 16.1

288.1 In bagasse to boilers:

Moist % bagasse Brix % bagasse

51.8

1.4

71.1

Softened water to boilers 0 In filter cake:

Cake % cane Moisture % cake

9.5

3 75

Raw water into factory 0 In molasses:

Molasses % cane DS % molasses

Evaporation from extraction plant:

3.8 78

3.5

4.2

Evaporation % cane 1

Boiler blowdown:

5.9

Total

288.1

Steam % cane HP Steam produced Blowdown % steam

Mixed Juice Flash:

Mixed juice % cane Heated Juice Temp.

In boiler smuts

Smuts % cane Moist % smuts

From cooling pond: Drift loss

Evaporation

Pan evaporation Jigger steam Final effect evaporation inj water temps‐in

‐out inj water flow to mill inj water flow from mill

Flow wet scrubbers:

Total

55.9 234.8

2.5

121.2

103

1.5 70

42.3 1.1

34.2 33

47.7 3125 3201

2.7

4.4

1.6 66

23.5

192.3

TOTAL SURPLUS = 95.8

FACTORY WATER SYSTEM

Evaporation Flash

MILLS CLARIFICATION EVAPORATION PAN HOUSE

Imbibition Filter Wash Water

High Quality Condensate

Condensate

Process Water

FEED WATER

STORAGE

LIME

PLANT Evaporation

FLOCCULANT

MAKE-UP

Evaporation

CONDENSATE

FOR PROCESS

USE

PROCESS COOLING TOWERS

Evaporation

Drift Less

Emergency Make-up

BOILERS BOILERS

SCRUBBERS

Drift Less

SERVICE COOLING TOWERS

LOW QUALITY

SERVICE WATER SYSTEM

Over Flow

Blow Down

Make-up

External Suppy

Boiler Pressure (bar) Maximum Sugar Content (ppm)

20 15

30 10

>40 Nil

Internal Balances within the Factory

• The quantity of condensate is much larger than the amount required in the boilers. Within the factory, condensate is recycled as boiler feed water and as process water.

• The best quality condensate is used for boiler feed water (usually the exhaust condensate from the first effect evaporator and the second effect vapor condensate.

CONDENSATE

• At higher pressures used to achieve very high thermal efficiencies, a steam transformer may be used (Magasiner, 1996)

• In evaporators and pans, the condensing steam is at higher pressure than the liquid being boiled.

• In juice heaters the pressure of the liquid in the tubes is higher than that on the steam side. Heater condensate should generally not be used for boiler feed water.

STEAM – CONDENSATE BALANCE SHEET 7,000 TCD MILLING RATE

STEAM GENERATION LIVE STEAM CONSUMER EXHAUST

AVAILABLE EXHAUST

CONSUMER CONDENSATE Boiler Equipt No.

of unit

Power (Hp)

Water Rate

Steam (lb/hr)

Exhaust (lb/hr)

Equipt Exhaust (lb/hr)

For Boiler For Process Use

Mill Equipt (lb/hr) Equipt (lb/hr) Capacity 453.074 1 1.00 500.00 25.96 12,982 12,333 3rd Heater 28,545 1st Evap 215,137 3rd Evap 105,645 % Gen 80.00% 2 1.00 800.00 25.96 20,772 19,733 Pans 53,295 2nd Evap 133,574 4th Evap 105,645 Steam Gen

362.459 Shredder 1.00 2,800.00 25.96 72,701 69,066 Evaporator 248,320 50% Pans 53,295 50% Pans 53,295

Mill Drive 5.00 650.00 25.96 84,385 80,165 Misc (5%) 16,508 1st Heater 27,929

2nd Heater 28,268

Power House 3rd Heater 28,545

5 MWTG 1.00 4500* 26.49 159,819 151,828 2.5 MWTG 2.00 STAND BY Boiling

House Make-up

for Exhaust 11,801 Total 362,459 333,125 Total 346,668 Total 402,006 Total 349,326

*Power in EXHAUST BALANCE BOILER FEED WATER BALANCE BAGASSE BALANCE

Exhaust available for process 333,125 lb/hr Steam Generated by boiler 362,459 lb/hr Bagasse from cane 99.43 ton/hr Exhaust requirement of the process 346,668 lb/hr Blowdown 5% 19,077 lb/hr Bagasse from fuel 76.36 ton/hr Desuperheated steam make-up 13,544 lb/hr Total feed water to boiler 381,536 lb/hr Excess Bagasse 23.07 ton/hr

6 ton/hr Condensate available for boiler feed

402,006 lb/hr Percent steam make-up 4% Excess condensate for boiler 20,470 lb/hr Specific Steam Consumption 1,090 lb/TC

• Sugar trace monitoring is normally done by measuring the condensate conductivity. It is an approximate method since it does not measure sugar at all. Sometimes spurious high conductivity readings are obtained and result in unnecessary dumping of condensate. Conductivity measurements cannot replace routine laboratory sugar trace checks.

The maximum amount of sugar contamination acceptable in boiler feed water depends on the boiler pressure.

PRESSURE- DEPENDENT QUALITY PARAMETERS

Pressure (bar) 20 40 60 80

Total hardness (mg/l as CaCO3)

10

20

0.5

Not Detectable

pH value 8.5-9.5 8.5-9.5 8.5-9.5 8.5-9.5

Oxygen (mg/l as O2 max. 0.05 0.02 0.01 0.005

Iron+ copper + nickel+ (mg/l) Not applicable 0.02 0.02

Total solids, alkalinity, Silica Numerical value depend on circumstances

Oil Not detectable

Inventory of Water Requirement

The water demand in the factory can be classified in two broad categories:

a) Cooling water which is directly reclaimable and

b) Process water which gets mixed up in the process and is reclaimable in different stages.

a) Cooling water requirements

Table 1 below gives the requirements of cooling water at different stations worked out on the basis of the makers’ prescription and/ or experience of operations.

Equipment

TABLE 1 Purpose

Basis

Total Requirement

for Estimation m3/hr

1. Mill Drivers: No. 4 standard Mill 6.8% m3/hr 28.00 horizontal steam turbines Turbines for each of two pedestal bearings and turbine (as split casing impulse type reduction per rating) provide with forced lubri- gear oil cation capable of develo- cooling ping 500 BHP 2. Mill Bearings: Mill size 850 Cooling 4.5m3/hr for 18.00 mm x 1675 mm journal dia of mill bearing each mill 425 mm total hydraulic (as calculated) pressure 270 tones 3. Power house Turbines: 1 No. Turbine and 18 m3/hr 18.00 horizontal multi/stage reduction gear (as per makers’ impulse steam turbine cooling manual) capable of developing 1500 KW with alternator 4. Diesel Generating Set: Cooling (As per makers’ 3.5 one Skoda diesel engine manual) generating set capable of developing 800 BHP

5. Sulphitation Station (i) 4 Nos. sulfur furnace of (a) Water 2.0 m3 per 4.0 continuous type (2 working) cooling jacket jacket

(b) Scrubber for 0.35 m3 per 7.0 cooling house (estimated)

(ii) Two electrically driven - (as per makers 3.5 water cooler air com- manual) pressor of 500 m3/hr and 250 m3/hr respectively

6. Vacuum Filter: One Oliver (a) For conden- (As per makers’ 10.80

condenser ser manual) (b) For vacuum pump bearing (c) For gland cooling of light and heavy filtrate pumps

7. Crystallizers: 7 Nos. water cooled crystallizers of 55 tonnes capacity each

for cooling C massecuites

0.8 m3 of cold water per ton of massecuite

10.80

8. Centrifugals: 15 Nos. Centrifugals of Robert's design of 450 kg/ charge capacity

For cooling of brake drum

(as per makers’ manual)

32.20

9. Hot liquor pumps For gland cooling, etc.

Estimated 3.15

TOTAL 129.50

b. Water for other process consumption

Table 2 below gives the requirement of water at various processing points:

TABLE 2

Purpose Basis Water Temp. Qty. of require- of estimation preferred ment in m3/hr

1. Imbibition 23% on cane Hot 730C 23.60

2. Make up water for boiler

5% of total generation

Hot 3.30

3. Milk of lime (by volume)

1.2% cane Hot 1.50

4. Oliver and Eimco (as per makers’ manual)

Hot 10.80

5. At pans 5% on cane Hot 6.50

6. Make up water for condensing system

3% loss on evaporation and 2% windage loss i.e. 5% of total spray capacity of 9 lakh gph

Cold 202.50*

7. Cleaning and washing

Estimated - 9.00

8 Water for drinking and other purposes ( a) for factory

20 gallon per head

Cold

3.85

(taking for 300 persons per shift)

(b) For colony

at 20 gallons

19.80

(for 5000 persons) (c) For Laboratory

per head by actual measurement

-

9.00

Total 87.25

Factory Water Requirements (Hugot, 1986 Ed. p. 893)

• Boilers. Taking the total steam requirement as 450 kg/t.c. and expressing the capacity of the factory in tch as

A. Water for the boiler must be assumed as 10-15 %, normally 10%. We have then 0.05A

• Washing of cane. Depends on conditions

• Cooling mill bearings; assuming 5 mills, say 0.20A

• Imbibition. Assuming 30% 0.30A

• Filtration. Assuming water 100% on cake 0.04A

• Cooling A masc; with a Werkspoor, we may reckon 1.5 l/l masc. and 130 1/1 of masc/tc= 0.130 x 1.5

0.20A

• Cooling B masc. Similarly 0.060 x 1.5 0.09A

• Cooling C masc. Similarly 0.040 x 1.5 0.06A

• Movement water for pans 0.02A

• Water for coolers 0.30A

• Water at centrifugals 0.01A

1.27A

Guidelines/ Suitable Designs of a Closed Water Circuit System (Mangal Singh, 1994)

• Evaporator station with multiple bleeding of vapors for vacuum pan use, juice heating by VLIH and by vapors bled from the evaporator bodies.

• Boiler feed water requirements being met by condensates from the pre-evaporator and 1st and 2nd bodies of the evaporators with arrangements of surplus storage and pumping back.

• Reclamation of all water in the form of condensates.

• Classification, collection and recycling of condensates for various process requirements and steam generation.

• Centralized collection of all hot condensates other than those for boiler use in an overhead collection tank providing for draw down lines incorporating preferential distribution system to various consumption points, e.g. lime slaking, cake washing, centrifugals and magmas, pans and maceration, etc.

• Provision in the central collection tank of raw water make-up to meet deficiencies if any, and its automated working with tank level control and resultant removal of parallel cold water lines from the process house or no provision thereof in case of new installations.

• Creating sub-circuits for total recirculation of cooling waters.

• Closed circuit of hot water for heating of massecuites in crystallizers and pugmills with provision of heating the water in circulation with thermostatic temperature control.

• Arrangements for collection of all cooling waters in a suitably sized masonry or steel tank which could also be designed to effect cooling as well as receiving the make-up water from the raw water source, as well as arrangement for collection of boiler and feed water tank overflows with provisions of pumping back when required and collection of surplus hot water from the overflow of the overhead hot water tank and its being pumped for maceration and/or back to the overhead tank for make-ups when required.

• Designing/lay-out of the boiling/ centrifugal house floor and drains to enable collection of spillages, leaks and washings for pumping back to the process.

• Reclaiming continuously the condensates from the VLIH whether in operation or not and diverting it to maceration.

• Arrangement to divert the lime house and grit washings into the condenser water channel to reclaim both the water and residual lime which helps to make up the condenser water pH.

Treatment & Recycling of Effluent

• All mills will have a surplus of water to dispose of. Disposal methods: 1. Fert-irrigation– effluent diluted with irrigation water 2. Ponding system– surplus water is contained during the crushing season and

treated during the off-season.

• In all other cases, the surplus has to be treated before it can either be re-used or returned to the watercourse. Attempts should be made to reduce the quantity and the concentration of dissolved substances in the effluent.

Treatment Methods

• Aerobic treatment • Anaerobic treatment • Recovery of leaks/ spillages • Cleaning • Distillery slops concentration and incineration

Disposal of Slops

• The following are the methods available for Disposal. o Fert-irrigation o Composting with Filter mud from Sugar mill. o Anaerobic Digestion to Generate Bio-gas and Composting. o Slops Concentration and Incineration in a Boiler. o Concentration and Incineration in a boiler is attracting a lot of attention, because of

cleanliness and economics. The incineration plant can meet 75% of the steam and power requirements of the Distillery.

T h i s c o n c e n t r a t i o n a n d incineration is a technology already established. The Figure shows the installation in a 80 KLPD distillery plant commissioned a few years ago. The operation of the plant has been very good.

Many more Projects are under implementation in India. China also has a few installations operating successfully.

Disposal of Other Effluents

• The sludge from Fermentation could be fed into the boiler, by mixing with slops or mixing with the supplementary fuel.

• The ash from the boiler is a source of potash and could be a field nutrient.

• The condensate from the Slops Evaporation plant and spent lees treated in a RO plant and the permeate used for molasses dilution or for Cooling tower make up. RO Reject taken to slops concentration plant.

• The blow down from cooling tower and boiler (harmless effluents) are cooled and taken to sugar plant's effluent treatment plant.

‘Zero Effluent’ Sugar Factory

• As defined is one where all surplus water leaving the factory meets the general discharge standards, without requiring conventional downstream effluent treatment. It does not mean that the factory has no exit water stream, as the water balance of any cane sugar factory results in a water excess due to the high water content in cane.

Typical Sugar Mill Zero Effluent Water Management

Imbibition Tank

Boilers & Scrubbers

Process C. Towers

Service C. Towers

Imbibition Tank

Boilers & Scrubbers

Process C. Towers

Service C. Towers

Surplus Water

Service Water

Flocculant & Lime

Overflows & Leaks

Evaporators

General Cleaning

Fire System

Stormwater Drains

Effluent Service

Water

Flocculant & Lime Overflows & Leaks R

e c

Evaporators y c l

General Cleaning e Fire System Stormwater Drains

2A 2B

Figure 2. Comparison of Standard and Zero Effluent water management systems

Key Principles of 'Zero Effluents' Water Management System

• Eliminate water usage where possible. (e.g. water- cooler air compressors were replaced with air-cooled compressors.

• Minimize usage where external water is essential (e.g. high-pressure water-jetting machines are used for factory cleaning)

• Minimize water losses from service cooling water circuits.

• Substitute external water with a process water stream of the minimum required quality.

• Substitute condensate with lower quality process water where appropriate. (This increases the amount of condensate available for users which require high quality water.)

• Monitor the use and availability of process water throughout the factory to ensure that factory users have an adequate supply of water at all times. Flowmeters are used to monitor water usage; and level transmitters, on storage tanks/sumps, are used to monitor water availability. Sufficient storage capacity or some form of make-up facility is provided for each source of process water, such that unsteady operating conditions are catered for.

emoval without

without any erature to

ike

APPLIED TECHNOLOGIES

ADVANTAGE

Reduction of steam consumption by 2-5%.

Centralized System of condensate r pumps.

No level and control valves required.

Exhaust condensate heat recovery contamination.

Light weight Stainless Steel Design.

Reduces Final condensate temp

required level for processes l imbibitons, washing filter-cake, dilution of molasses etc.

CONDENSATE FLASH RECOVERY

CONDENSATE FLASH CIGAR

Prevent the Escape of Heat Use the Heat Over Again

DIRECT CONDENSER (DC) vs SURFACE CONDENSER (SC)

DIRECT CONDENSER (DC)

EXAMPLES:

Barometric Condensers counter-current type parallel-current type multi-jet

SURFACE CONDENSER (SC)

EXAMPLES:

Water-cooled Shell and Tube Plate type Spiral type

Air-cooled Fin Fan Condenser

DC SC

MULTI-JET CONDENSER

MULTI-JET with CONTROL VALVES

FIN FAN TUBE

VAPOR FROM EVAP.

MIXED JUICE FROM MILL

MIXED JUICE TO HEATER STATION

SEALING WATER

VACUUM LINE

LAST CELL EVAPORATOR

CONDENSATE SEPARATOR

JUICE HEATER

VAPOR

BAROMETRIC CONDENSER

CONDENSATE TO

SEALING TANK

VAPOR LINE JUICE

HEATER Use Waste Heat

LSC VAPOR-LINE JUICE HEATER PERFORMANCE PARAMETER Mixed Juice Flow (tons/hr)

RANGE 260-280

AVE. 270

HEAT TRANSFERRED to MIXED JUICE Q=MCp (To-Ti)

M.J. Inlet Temp. (0C) 32-38 35 Q=270 x 0.9 x 17 M.J. Outlet Temp. (0C) 50-55 52 Q=4131 Mcal or 4804 kWh Vapor Temp. (0C) 60-63 62 Condensate Flow (tons/hr) 4.8-9.9 6.1 EQUIVALENT AMOUNT OF EXHAUST @ 620 watt-h/kg = 7.7 tons/hr

AVE. CONDENSATE FLOW 6.1tons/hr

SAVINGS IN COOLING WATER 305 tons/hr or 1343 gpm

ADVANTAGES OF SURFACE CONDENSER

• CONDENSED VAPOR DOES NOT MIX AND BECOME POLLUTED • CONDENSATE CAN BE RECYCLED OR RECOVERED • NO EXTRA COOLING WATER TO BE HANDLED • NOT MUCH AFFECTED BY FLUCTUATIONS IN THE SUPPLY OF THE

COOLING MEDIUM • I F I N TA N D E M W I T H A B A R O M E T R I C C O N D E N S E R O R A

“COMPENSATOR”, WILL MAKE THE OPERATION OF THE VACUUM PUMP MORE EFFICIENT BECAUSE OF IMPROVED DEGASSING AND SUB- COOLING OF INCONDENSABLE GASES RESULTING TO REDUCED LOAD OF THE VACUUM PUMP.

• BENEFITS OF SURFACE CONDENSER

- STEAM SAVINGS due LOST HEAT RECOVERY - RECOVERY OF CONDENSATE FOR PROCESS WATER - COST SAVINGS IN THE PRODUCTION, TREATMENT AND CONDITIONING

OF FRESH WATER - COST SAVINGS IN WASTE WATER TREATMENT

IN SHORT: WATER & ENERGY SAVINGS!

LSC SURFACE CONDENSER ENERGY SAVINGS HEAT SAVED Q=MCp (To-Ti) Q=20 x 1 x (60-28) Q=640 Mcal or 744 kWh

EQUIVALENT AMOUNT OF EXHAUST @620watt-h/kg=1.2 tons/hr

AVE. CONDENSATE FLOW 20 tons/hr

SAVINGS IN BAGASSE 0.52 tons/hr

Feed Temperatu

re Gauge

Feed

Pressu re

Gauge

Pump

Low

TYPICAL RO SYSTEM

Suction Suction

Chemic al

Addition

Pressu re

Gauge

Pressu re

Switch

Feed Pressure

Control Valve

Reverse Osmosis

Membrane Elements

Pressure Vessel

Permeate Flow

Concentra Flo te

Combined

5 - 10µ Filter

Feedwater Sampling

Point

High

Pressure Pump

RO PuFmeped

Discharge

Flow Indicator

Concentrate

Pressurew Gauge

Brin

e Concentrat e Sampling

Valve

Permeate Sampling Point

Flow Indicator

Permeate Flow

Sampling Point

Dr. Chou’s CHALLENGES FOR 21st

Permeate Flow

to Point of Use

to Drain

CENTURY - NEW SUGAR REFINERY DESIGN CRITERIA

• WATER USAGE Take 100 kg of 65 brix sugar liquor:

(a) Water needed is 35 kg per 65 kg of raw sugar (b) Water to be recovered by surface condenser is 21.7 kg (c) Total water needed % raw sugar:

= (35-21.7) x 100/65 = 20.5%

Conclusion: why the average usage is over 60%

The problem: Humans use more and more water each year. Today at least 400 Million people have severe water shortages. Over 70,000 different water contaminants have been identified. There are 12,000 different toxic chemicals in industrial use today, and more than 500 new chemicals are developed each year.

The solution:

• WATER CONSERVATION • WATER RECYCLING • WATER TREATMENT

If all new sources of contamination could be eliminated, in 10 years, 98% of all available ground water would then be free of pollution.

Tem

pera

ture

Rel

ativ

e to

188

0-18

99 M

ean

(°C

)

Introduction: Climate Change • Climate change – caused by both natural events (like volcanic eruptions) and human

activities (Greenhouse gas emissions) • There is now a global concern about climate as indicated by:

o The melting of polar caps/glaciers, radical shifts in weather patterns (El Niño/ La Niña)

o Increased occurrence of dramatic weather conditions such as hurricanes and droughts in all parts of the earth

o Increasing Global – Mean Temperature. • Climate change is primarily attributed to human activities particularly, the release of

greenhouse gases (GHG) from energy generation, industrial activity, land use and forestry which in turn, cause global warming.

1.0

0.8

0.6

0.4

Smooth Curve

Annual values

0.2

0.0

-0.2

-0.4

1860 1880 1900 1920 1940 1960 1980 2000

Year

Sea ice

Green House Gas Effect

• Earth is kept warm by its atmosphere

• Without atmosphere average surface temperature would be 18-deg. C

• Heat from sun passes through atmosphere warming it up, and most of it warms surface of earth

• As earth warms up it emits heat as infra-red

Solar

SUN

Some solar radiation is

reflected by the Earth and the atmosphere.

ATMOSPHERE

Some of the infrared radiation is absorbed and

radiation. Some heat is trapped by atmosphere

• Green House Gases make the atmosphere trap more of radiation, so it gradually warms earth up more.

radiation passes through the clear atmosphere.

Most radiation is absorbed by the Earth’s surface and warms it.

EARTH

re-emitted by the greenhouse gases. The effect of this is to warm the surface and the lower atmosphere.

Infrared radiation is emitted from the Earth’s surface.

Human Sources of GHGs

Carbon Dioxide (CO2) – Most prevalent GHG Methane (CH4) – Second most common, 21x the potency of CO2

Nitrous Oxide (N2O) – 310x the potency of CO2

Other Gases – HFCs, PFCs, and SF6 = range 600 – 23900x potency of CO2

Energy Generation Industrial Processes

Transportation Land Use:

Agriculture & Forestry

Tem

pera

ture

Rel

ativ

e to

188

0-18

99 M

ean

(°C

)

GHG and Environmental Impacts Changes in temperature, weather patterns and sea level rise

Coastal Areas:

Erosion and flooding Inundation

Change in wetlands

Agriculture: Changes in crop yields Irrigation demands, Productivity

Human Health: Weather related

mortality Infectious disease Air quality - respiratory

illness

Water Resources: Changes in water supply

and water quality Competition/Trans-border

Issues

Forests: Change in Ecologies, Geographic range

of species, and Health and productivity

Industry and Energy: Changes in Energy demand Product demand &

Supply

Rising temperatures results in changing weather patterns • Melting polar caps, glaciers • Shifts in weather patterns

• Increased occurrence of dramatic weather such as hurricane

Global-Mean Temperatures

1.0

0.8

0.6

0.4

0.2

0.0

-0.2

Annual values

Smooth Curve

-0.4

1860 1880 1900 1920 1940 1960 1980 2000

Year

SAVE WATER

THE WORLD IS IN

YOUR HANDS

Positive Proof of Global Warming