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Water Technologies Potable water production by means of desalination and other Low-pressure Membrane applications Appropriate Technologies Conference,

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Presentation on theme: "Water Technologies Potable water production by means of desalination and other Low-pressure Membrane applications Appropriate Technologies Conference,"— Presentation transcript:

1 Water Technologies Potable water production by means of desalination and other Low-pressure Membrane applications Appropriate Technologies Conference, Cape Town 3 & 4 September 2007

2 Slide 2 AWA_Advanced Water Treatment Workshop Water Technologies Water Wise Society, my dear, is like salt water, good to swim in but hard to swallow. Arthur Stringer Arthur Stringer Water is the most neglected nutrient in your diet but one of the most vital. Kelly Barton Kelly Barton [Water is] the only drink for a wise man. Henry David Henry David A chemical industry lobbying group defends its stand against strict water pollution laws. Spokeswoman Flo Brown elaborates: “The chemicals in the water act as a preservative, which extends the freshness period of the water by several decades. We think that’s a good deal for consumers.” (1970)

3 Slide 3 AWA_Advanced Water Treatment Workshop Water Technologies Membrane Improvements Costs have dropped by 50% in 20 years Productivity has increased by 100% Fouling resistant membranes Chlorine Resistant, Low Pressure membranes Increased membrane manufacturer competition Membranes have become a commodity Improved scale inhibitors Improved energy efficiency of ancillary equip Variable Speed Drives Energy recovery

4 Slide 4 AWA_Advanced Water Treatment Workshop Water Technologies Reverse Osmosis How does it work? A Leaf Growth Air Soil Root System Root Wall (semi-permeable Membrane) Water Nutrient

5 Slide 5 AWA_Advanced Water Treatment Workshop Water Technologies Air Soil Root System Root Wall (semi-permeable Membrane) Ammonium Sulphate

6 Slide 6 AWA_Advanced Water Treatment Workshop Water Technologies Air Soil Root System Root Wall (semi-permeable Membrane)

7 Slide 7 AWA_Advanced Water Treatment Workshop Water Technologies Fresh WaterConcentrated Salty Water Applied Pressure Applied Pressure Reverse Osmosis

8 Slide 8 AWA_Advanced Water Treatment Workshop Water Technologies What if the membranes fail? Membrane degradation is slow Routine cleaning maintains membrane condition Ample time to source replacement membranes (good stock levels internationally) Not a big issue, because:

9 Slide 9 AWA_Advanced Water Treatment Workshop Water Technologies How long do RO membranes last? End of membrane life is project specific (quality or quantity?) 3-7 years, but: Type of pre treatment can increase life Microfilter pre treatment - 5 years or more Sand filter pre treatment - 3 years Operating cost balance - Higher Pressure (energy) & frequent cleaning vs capital outlay? You don’t need a full set - keep the best and replace the worst

10 Slide 10 AWA_Advanced Water Treatment Workshop Water Technologies What about a project that was a disaster? Failure to understand feed water Change in feed water Designer inexperience/lack of knowledge Competitive tendering awards contracts to the company that “cut corners” Poor commissioning Inadequate pre treatment Desalination failures occur because:

11 Slide 11 AWA_Advanced Water Treatment Workshop Water Technologies Early failures of RO occurred in the first applications of a new technology RO is now a mature technology Failure causes are well understood and predictable Correct design and sizing eliminates the potential for failure DON’T PANIC

12 Slide 12 AWA_Advanced Water Treatment Workshop Water Technologies Are they hard to maintain and operate? Daily checks = 1/2hr Weekly checks = 1hr Daily monitoring can be done remotely Cleaning a semi-automatic process every 3-6 months No

13 Slide 13 AWA_Advanced Water Treatment Workshop Water Technologies Design Issue – Pre treatment Invest time & money to define the full range of feed conditions (algae, salts, pH, turbidity etc) Opt for easy to treat water sources Extremes of feed conditions must be the design basis for pre treatment Choose pre treatment that gives stable treated water quality Don’t experiment in remote locations Give greater importance to proven technical solutions over price “Poor Pretreatment is the No. 1 killer of RO Systems”

14 Slide 14 AWA_Advanced Water Treatment Workshop Water Technologies Design Issue - Recovery Aim for: TDS < 2000mg/L80-90% TDS 2000-5000mg/L70-80% TDS 5000-10000mg/Lup to 75% Seawater (36000mg/L)40-45% Sparingly soluble salts may restrict further DO make brine disposal the key driver for increasing recovery DON’T use the lure of reduced operating cost as the driver for high recovery Recommendations

15 Slide 15 AWA_Advanced Water Treatment Workshop Water Technologies Typical water production costs for desalination plants and conventional water treatment plants Range is for East Coast water (lowest cost), South Coast water and West Coast water (highest cost) 5.80 – 8.30 Costing model (5 Ml/d RO seawater desalination plant) Range is for low TDS (2 000 mg/l)(lower cost) and high TDS (12 000 mg/l)(higher cost) 2.40 – 4.90 (Costing model (5 Ml/h RO groundwater desalination plant) Range is for low TDS (2 000 mg/l)(lower cost) and high TDS (12 000 mg/l)(higher cost) 5.30 – 9.40 Costing model (15 m 3 /h RO groundwater desalination plant) Cost includes electricity, labour, membrane replacement (every 5 years) and pump maintenance. 2.26 Boesmansriviermond ( 45 m 3 /h RO seawater desalination plant) Relative high cost for management functions and transport due to remote location of the RO plant. 7.81 Bitterfontein (12 m 3 /h RO groundwater desalination plant) Conventional water treatment plant. Cost includes purchase of raw water. 1.04 Withoogte (72 Ml/d treatment plant) Includes raw water costs (which include the new Berg River Water project) 1,05 – 1,25 City of Cape Town (various plants) Treatment plant includes ozonation and dissolved air flotation for treating eutrophied water. Cost includesR 1.52/kl for purchase of raw water. 2.52 Midvaal(250 Ml/d treatment plant) Conventional water treatment plants. Cost includes purchase of raw water. 2.53 Rand Water (For 6 large water treatment plants, treating a total of 5 260 Ml/d) Cost includes purchase of raw water.3.39 Amatola Water(For 14 water treatment plants) Notes Water production cost (R/kl) Treatment System Desalination plants Conventional water treatment

16 Slide 16 AWA_Advanced Water Treatment Workshop Water Technologies Low Pressure MEMBRANES What are Low Pressure (LP) Membranes How do they operate Different LP Membrane Configurations LP Membrane Applications LP Membrane Market Acceptance and GROWTH LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

17 Slide 17 AWA_Advanced Water Treatment Workshop Water Technologies INTRODUCTION Filtration Spectrum Pressure > 5 Bar > 2 Bar > 0.5 Bar > 0.2 Bar MOL WT < 100 < 1,000 < 100,000 < 1,000,000 MICRON < 0.001 0.001 to 0.01 to 0.1 to 1.0 to 0.01 0.1 1.0 10.0 LOW PRESSURE MEMBRANES LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

18 Slide 18 AWA_Advanced Water Treatment Workshop Water Technologies INTRODUCTION Typical LP Membrane Surface LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

19 Slide 19 AWA_Advanced Water Treatment Workshop Water Technologies OPERATION Filtration – Memcor Hollow fibre FEED FILTRATE Feed water is outside membrane Filtered water flows through membrane to the lumen LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

20 Slide 20 AWA_Advanced Water Treatment Workshop Water Technologies OPERATION Filtration Fouling on the surface of the membrane only FEED FILTRATE LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

21 Slide 21 AWA_Advanced Water Treatment Workshop Water Technologies OPERATION Backwash method Raw water remains outside membrane Filtrate is pushed backwards through membrane Air scours outside of membrane surface LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

22 Slide 22 AWA_Advanced Water Treatment Workshop Water Technologies LP MEMBRANE CONFIGURATIONS LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

23 Slide 23 AWA_Advanced Water Treatment Workshop Water Technologies LP MEMBRANE CONFIGURATIONS - Pressurised (Most Common) Raw Water Waste Treated Water Norit Hyflux Memcor Pall FEATURES Each membrane has own pressure vessel Higher operating pressures Easily packaged LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

24 Slide 24 AWA_Advanced Water Treatment Workshop Water Technologies LP MEMBRANE CONFIGURATIONS - Submerged Raw Water Waste Treated Water MemcorZenon FEATURES Membranes sit in Open Tank Typically Low capital cost Typically Low operating cost Suited to Retrofit into existing Clarifiers/Sandfilters LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

25 Slide 25 AWA_Advanced Water Treatment Workshop Water Technologies LP MEMBRANE MARKET Installed Capacity EXPONENTIAL GROWTH WIDESPREAD MARKET ACCEPTANCE LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

26 Slide 26 AWA_Advanced Water Treatment Workshop Water Technologies LP MEMBRANE MARKET GROWTH LP MEMBRANE MARKET Reasons for Growth 22% 2% Superior performance vs traditional technologies Declining fresh water sources or quality More stringent regulatory requirements Growing Market acceptance LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

27 Slide 27 AWA_Advanced Water Treatment Workshop Water Technologies LP MEMBRANE MARKET GROWTH LP MEMBRANE MARKET Trend 22% 2% Cost of Water Cost of Membranes LP MEMBRANES INTRODUCTION LP MEMBRANE OPERATION LP MEMBRANE CONFIGURATIONS LP MEMBRANE APPLICATIONS LP MEMBRANE MARKET

28 Slide 28 AWA_Advanced Water Treatment Workshop Water Technologies Potable Water Production Typical Potable Water Quality: CleanTurbid Turbidity< 20 NTU< 100 NTU Colour< 10 HCU< 100 HCU Algae< 100 cells/mL< 10 4 cells/mL Hardness< 200 mg/L pH6.0 - 8.5 CoagulantNil< 20 mg/L

29 Slide 29 AWA_Advanced Water Treatment Workshop Water Technologies Joyce Rd WPP - Tauranga, NZ 36 ML/d (9.5MGD) Pressurised Plant Operational Dec ‘97 Highly variable feed water LRV 5 (> 1 µm) filtrate quality

30 Slide 30 AWA_Advanced Water Treatment Workshop Water Technologies Oropi Rd - Tauranga, NZ Sister plant to Joyce Rd 32 ML/day (8.5MGD) Expandable to 54ML/day Commissioned June, 2002 Backwash recovery via clarifier

31 Slide 31 AWA_Advanced Water Treatment Workshop Water Technologies Aqua 2000 - Bendigo, Vic Capacity 126 ML/d (33 MGD) Surface water (Colour 5 - 20 HCU) Tight water quality targets:  Turbidity at each filter < 0.1 NTU  Particles at each filter < 10 particle/mL  Protozoa > Log 4 removal  THMFP < 80  g/L  Algae Toxins  Colour, Taste & Odour

32 Water Technologies Thank you very much for your attention.


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