Appropriate Technology for Water Treatment in Developed and Developing Countries

Transcription

1 Appropriate Technology for Water Treatment in Developed and Developing Countries Chris Schulz, UNC-ESE Class of 1982 Okun Memorial Symposium November 7, 2008

2 Presentation Topics Water treatment milestones since 1982 Defining appropriate technology for water treatment Advanced water treatment processes for developed countries Basic water treatment processes for developing countries CDM Engineers Without Borders

3 My preparation Review Schulz/Okun book request to friends and colleagues Google keyword search UNC photo album

4 st MF Hired Membrane by CDM System Installed in Australia USEPA DW Reg s 1993 Milwaukee Crypto Outbreak SWTR IESWTR Stage 1 DBPR 2000 LT2ESWTR 2006 LT2ESWTR/Stage 2 DBPR Patent on UV Disinfection of Crypto 2007 AP Article on Phameceuticals in Drinking Water 1980s 1990s UNC Graduation/Hired by World Bank Schulz/Okun Book UN International Water & Sanitation Decade 1991 Water for People Began 2000 Engineers Without Borders Began UN Millennium Project Commissioned 2004 USA Mellennium Challenge Corporation Established

5 Projected Global Growth Rates Across Water/Wastewater Technology Spectrum Water Treatment Markets - CAGR % 20% 15% 10% 5% 0% MBR MF/UF Membranes UV Treat. WW Treat. & Reuse Ion Exchange RO DW & PW Treat. Equip. Ozone Disinfection Activated Carbon for DW Source: GE Water Presentation, CDM Water Forum, 2007

6 UN Mellenium Development Goal for Water and Sanitation Goal: Cut in half by 2015, proportion of people without sustainable access to safe drinking water and basic sanitation Benefits: $1 investment earns economic return of $3-4 10% global reduction of diarrheal episodes $7.3 billion health-related cost avoidance $750 million global value of adult working days due to less illness USA Mellenium Challenge Corporation: $530 million invested in 7 partner countries thru 2008

7 Defining Appropriate Technology (AT) Working Definition Design practice, whether it be in a developed or developing country, should strive to optimize the total investment of available capital, material and human resources, recognizing the limited resources of each that may exist. Daniel Okun, 1984

8 Defining Appropriate Technology (AT) Economic Considerations Developed Countries: An investment of about $600,000 in capital equipment would be warranted to replace an around-the the-clock attendant in USA based upon total cost of $20,000 per year for each of four persons, 15-year life of equipment and 10% interest.. Developing Countries: $20,000 might be the maximum investment warranted, based upon a wage of $1,000 per year, 10-year equipment life and 20% interest. Daniel Okun, 1984

9 Common attributes of water treatment technologies in developed countries Proprietary equipment, chemicals and support services Highly automated and instrumented plant High-rate processes Multi-stage advanced treatment barriers New focus on sustainability (triple bottom line)

10 Common attributes of sustainable water treatment projects in developing countries Labor-intensive solutions Reliance on hydraulic solutions Locally produced equipment Indigenous chemicals Low-rate processes Basic treatment processes Manual operation, monitoring and control

11 Typical reasons for widespread use of IT in developing countries Expatriate engineers only familiar with highly mechanized treatment processes used back home Utility manager desires only the best which erroneously means the latest or most complex technology Turnkey contractors typically select capitalintensive designs because of greater profitability Professors tend to focus on most advanced technology so students are not exposed to technology appropriate to developing countries Seeds of Change: Engineers Without Borders Water For People and Water Corps University of Colorado Curriculum on Engineering for Developing Countries

12 Advanced Water Treatment Processes in Developed Countries Coagulant Powder Activated Carbon Chlorine Raw Water Rapid Mix Flocculation Sedimentation Filtration Clearwell High Service Pumps Reject Solids to Sewer Potable Water Conventional Treatment Coagulant H 2 O 2 Chlorine Ammonia Raw Water Rapid Mix Flocculation Sedimentation Settled Water Ozone Biological Filters Clearwell High Service Pumps Potable Water ALTERNATIVE B Reject Solids to Sewer Advanced Ozone/BAC Treatment

13 Advanced Water Treatment Processes in Developed Countries Raw Water Coagulant Powder Activated Carbon Rapid Mix Chlorine Ammonia Advanced Water Treatment Processes: Ozone and Ozone/AOP Membranes Clearwell Ozone and Ozone/AOP UV Disinfection and UV/AOP High Service Pumps Potable Water Reject Solids to Sewer High-Rate Direct Clarification Membrane Treatment Ion Exchange Processes (MIEX) Coagulant Biological Filtration Chlorine Raw Water Rapid Mix Flocculation MF/UF Pressure Membranes MF/UF Submerged Membranes Sedimentation Membranes Ozone Contact Biological Filters On-Site Chlorine/Hypo Generation Clearwell High Service Pumps Reject Solids to Sewer Ammonia Potable Water Advanced Membrane/Ozone/BAC Treatment

14 High-Rate Clarification (Superpulsator, DAF, Actiflo) Effective removal of turbidity, color and TOC 5 to 20 times smaller footprint than HF sedimentation basins Equipment-intensive intensive processes Energy-intensive processes Retrofit vs. physical expansion tradeoffs

15 Ozone Disinfection/Oxidation Powerful disinfectant (Giardia, Crypto, virus) No chlorinated DBPs Multiple oxidation benefits (T&O, Fe/Mn, Color, pesticides, PPCPs) May require control strategies for removing BDOC and bromate New technologies for improved G/L mixing and MTE Concentration (ug/l) Pre-CL2/ Post-CL2 Ozone / Post-CL2 TTHMo HAA5o 0 Aug-97 Sep-97 Nov-97 Jan-98 Feb-98 Apr-98 Jun-98 Jul-98 Date Lanier WTP, Gwinnett County, GA

16 UV Disinfection/AOP Cost-effective for Giardia/Crypto disinfection (but not virus) BAT for unfiltered supplies BAT for nitrosamines removal (NDMA) UV/AOP effective for T&O removal but requires: times more power Peroxide quenching system UV Power Requirements (Kwh/1.000 gal) Jan DISINFECTION Feb Mar Apr May Jun T&O EVENT DISINFECTIO N Jul Aug Sep Oct 10 5 Nov Dec Peroxide (mg/l)

17 Low-Pressure MF/UF Membranes Low turbidity (< 0.05 NTU) > 4-log Giardia and Cryptosporidium removal Less reliance on pretreatment Smaller footprint Proprietary process Fully automated process Requires piloting to determine flux rates and fouling characteristics Cost-competitive with conventional treatment

18 Source Selection and Treatment Requirements in Developing Countries Basic Water Treatment Processes: 1. Groundwater: Pretreatment for Sediment Removal Pumping & Possibly Chlorination Locally Available Chemicals (Alum, 2, Iron Lakes or Streams: Salts, Lime, Hypochlorite) Slow Sand Filtration Solution-Type Chemical Feeders, Saturators 3. Rivers: Pretreatment and SSF Hydraulic Mixing and Flocculation Raw Water Coagulant Rapid Mix Horizontal-Flow Sedimentation Chlorine 4. Turbid Rivers: Conventional Treatment Rapid Filters with Inter-Filter Backwash Slow Sand Filters Flocculation Slow Sand Sedimentation Filters Filtration Clearwell Reject Solids to Sewer High Service Pumps Potable Water

19 Hydraulic Mixing and Flocculation Mixing achieved by head loss (not horsepower) Weirs/flumes can provide near instantaneous mixing No imported equipment Simplified O&M Tapered flocculation without flow short- circuiting Mixing energy dependent on plant flow

20 Slow Sand Filters No power or chemicals Significant bacteria reduction (3-4 4 log) Built with local labor and materials Cleaned by unskilled labor Requires large land area (FLR = 0.1 gpm/sft) Limited to turbidity < 50 NTU

21 Kiosk Membrane Treatment System (SkyJuice( Foundation) Treats turbid water sources (500 NTU) without chemicals Significant protozoa/bacteria removal (3-4 4 log) Requires only 1 m of head for operation Manually backflushed Can produce 10,000 liter/day $2,000/unit AT for entrepreneurial water vendors

22 Kiosk Membrane Treatment System (SkyJuice Foundation)

23 HWTS Ceramic Filter Systems (Potters for Peace Ron Rivera) Colloidal silver-enhanced enhanced ceramic water purifier 30 filter factories worldwide 300,000 filters serving 1.5 million people Profitable microenterprises There is now conclusive evidence that simple, acceptable, lowcost interventions at the household level are capable of dramatically improving the microbial quality of household water ands reducing the attendant risk of diarrheal disease and death. Mark Sobsey, UNC WHO Report, 2002 Produces liters/hr $10-15/unit 15/unit with plastic receptacle and tap

24 CDM Engineers Without Borders Fall 2007 Launched Partnership Program EWB Local Chapter Representatives ~27 chapters to date Acts as liaison to local CDM office, contact point Funding set aside for employee grants Up to $2,500 per employee Covers travel/professional costs Not intended for project fundraising

25 Here s s to the WRE Class of 1982! SCHULZ/OKUN BOOK DOWNLOADED AT: %20in%20Developing%20Communities.pdf