THE ARSENIC BIOSAND FILTER (ABF) PROJECT: DESIGN OF AN APPROPRIATE HOUSEHOLD DRINKING WATER FILTER FOR RURAL NEPAL Final Report July 2003 Prepared for Rural Water Supply and Sanitation Support Programme Butwal, Nepal and Environment and Public Health Organization Kathmandu, Nepal By Tommy Ngai, Massachusetts Institute of Technology Sophie Walewijk, Stanford University 2003 Tommy Ngai. All Rights Reserved ACKNOWLEDGEMENTS Tommy Ngai would like to thank the Lemelson Foundation, and MIT IDEAS Competition for funding my project; RWSSSP and FINNIDA for their field support, comfortable accommodation, transportation, and friendship; ENPHO for their research assistance; and IBS for their hospitality. Tommy Ngai would like to thank his supervisor and friend, Susan Murcott, for her inspiration and guidance to motivate him to pursuit this project. Her meticulous review of this report is greatly appreciated. Sincere thanks are given to the MIT Department of Civil and Environmental Engineering, and all members of the MIT Nepal Water Project. The development of the Arsenic Biosand Filter would not be possible without the years of research contribution and bright ideas by these members. Finally, Tommy Ngai would like to thank Ms. The Best Employee Ever for her good company and her dedication to the project. Tremendous level of synergy and excitement was experienced as a result of highly effective teamwork. Sophie Walewijk would like to thank Mr. Super Nice Boss for his good friendship and for the opportunity he gave her to continue working on an arsenic removal solution appropriate for developing countries. Sophie Walewijk would also like to thank Professor Leckie for his support on the project, and her Ph.D. Principal Investigator, Dr. Reinhard, for allowing her to devote a good chunk of her time on this project. i THE ARSENIC BIOSAND FILTER (ABF) PROJECT: DESIGN OF AN APPROPRIATE HOUSEHOLD DRINKING WATER FILTER FOR RURAL NEPAL by Tommy Ngai, Massachusetts Institute of Technology Sophie Walewijk, Stanford University ABSTRACT A household-level drinking water filter (Arsenic Biosand Filter, ABF), appropriate for rural Nepal, was developed at Massachusetts Institute of Technology to simultaneously remove arsenic and pathogens from tubewell water. The ABF can be entirely constructed by trained local labor using locally available materials. A laboratory study and a three- months pilot study were conducted in Nepal from September 2002 to January 2003 to evaluate the performance of the filter under various setups, to investigate long-term removal efficiencies, to improve the filter design, and to implement the filter in arsenic- affected villages. The Arsenic Biosand Filter was found to be effective in removing arsenic (range = 87 to 96%, mean = 93%), total coliform (range = 0 to >99%, mean = 58%), E. Coli (range = 0 to >99%, mean = 64%), and iron (range = >90 to >97%, mean = >93%). The users liked the high flowrate (range = 4 to 23 L/hr, mean = 14 L/hr), simple operation, minimal maintenance, as well as the clean-looking and good-tasting water coming out of the filters. They think the filter is a durable, permanent solution to their drinking water problems. On-going research at MIT and Stanford will seek to further enhance filter performance, and user-friendliness. Implementation schemes and cost recovery issues were discussed with local partners, including the Rural Water Supply and Sanitation Support Programme (RWSSSP) and Environment and Public Health Organization (ENPHO). These agencies will proceed with implementation plans. ii TABLE OF CONTENTS ACKNOWLEDGEMENTS ..........................................................................................................................I ABSTRACT ................................................................................................................................................. II TABLE OF CONTENTS...........................................................................................................................III LIST OF FIGURES......................................................................................................................................V LIST OF TABLES.................................................................................................................................... VII 1. PROJECT BACKGROUND ................................................................................................................... 1 2. PROJECT MOTIVATION AND GOALS............................................................................................. 3 3. DRINKING WATER SITUATION IN NEPAL.................................................................................... 4 3.1 ARSENIC CONTAMINATION .......................................................................................................... 4 3.2 PATHOGENS CONTAMINATION ..................................................................................................... 5 4. ARSENIC BIOSAND FILTER (ABF) THEORY ................................................................................. 6 4.1 ABF DESIGN................................................................................................................................7 4.2 ARSENIC REMOVAL...................................................................................................................... 8 4.3 PATHOGEN REMOVAL .................................................................................................................. 9 4.4 ABF MANUFACTURING AND INSTALLATION PROCEDURE.......................................................... 11 4.4.1 Manufacturing ...................................................................................................................... 11 4.4.2 Installation Procedure..........................................................................................................12 4.5 ABF OPERATION PROCEDURE ................................................................................................... 14 4.6 ABF CLEANING PROCEDURE ..................................................................................................... 15 4.7 ENPHO’S ARSENIC BIOSAND FILTER SETUP ............................................................................. 16 4.8 RWSSSP’S 3-KOLSHI FILTERS SETUP ....................................................................................... 16 5. ANALYTICAL METHODS.................................................................................................................. 17 5.1 ARSENIC..................................................................................................................................... 18 TM 5.1.1 Industrial Test Systems Inc. Arsenic Check Field Test Kit................................................ 18 5.1.2 Perkin-Elmer Graphite Furnace Atomic Absorption Spectrometry (GFAAS)...................... 21 5.1.3 ENPHO New Arsenic Field Test Kit..................................................................................... 22 5.1.4 SOLAAR 969 Hydride Generation Atomic Absorption Spectrometer (HGAAS) .................. 23 5.2 TOTAL IRON ............................................................................................................................... 24 5.2.1 HACH Portable Iron Test Kit Model IR-18.......................................................................... 24 5.3 BACTERIA .................................................................................................................................. 25 5.3.1 Millipore M-Coliblue24 Broth, Membrane Filtration and Incubation................................. 26 5.3.2 ENPHO Presence/Absence H2S Bacteria Test Vials ............................................................ 29 5.4 FLOW RATE................................................................................................................................30 6. LABORATORY EXPERIMENTS AT RWSSSP................................................................................ 31 iii 6.1 LABORATORY EXPERIMENTS OVERVIEW ................................................................................... 31 6.1.1 Filter Arrangements .............................................................................................................31 6.1.2 Main Experiment .................................................................................................................. 35 6.1.3 Additional Experiments ........................................................................................................ 36 6.2 RESULTS AND DISCUSSIONS ....................................................................................................... 38 6.2.1 Main Experiment .................................................................................................................. 38 6.2.2 Additional Experiments ........................................................................................................ 44 7. PILOT STUDY IN SARAWAL AND DEVDAHA VILLAGE DEVELOPMENT COMMITTEES (VDCS) – SEPTEMBER 2002 TO JANUARY 2003 ............................................................................... 48 7.1 PILOT STUDY OVERVIEW ........................................................................................................... 48 7.1.1 Installation............................................................................................................................ 48 7.1.2 Monitoring by RWSSSP .......................................................................................................