CoHemis International Conference Green Communities June 18 20 2008 Daniel G. Concepcion, Department of Mechanical Engineering Arelys V. Fonseca, Department of Chemical Engineering Sacha D. Sanchez, Department of Electrical and Computer Engineering Yahaira Lugo and Juan Falcon, Department of Civil Engineering and Surveying Dr. Sangchul Hwang, Faculty Advisor Department of Civil Engineering and Surveying University of Puerto Rico at Mayagüez Rajib Sinha, Shaw Environmental & Infrastructure, Inc., Cincinnati 1
Agenda Introduction Status of Rural Supply system in Puerto Rico Rio Piedras, Cain Alto San German Characterization Telemetry water quality monitoring of San German Filtration Plant San German Filtration system profile Drum filtration Drum filtration system EPA Cincinnati preliminary evaluation Construction (components) Configuration (sand, series, parallel, backwash sequence) Troubleshooting Set up Solar Design Site Monitoring Results Turbidity background Dissolved Oxygen ph Bacteriological background (method) Chlorination (methods, instruments) Discussion and viability Cost analysis Future Work Conclusions Questions 2
Status of Rural Water Supply Systems in Puerto Rico Rural drinking water supply system in PR have experienced poor water quality and insufficient quantity, specially for non PRASA communities. Treatment by population category for non-prasa systems. ( Shaw Environmental, INC. 2007) 100 Number of Systems 90 80 70 60 50 40 30 20 10 No Treatment Chlorination,Not Specified Chlorination, Tablets Hypochlorination Filtration Sedimentation Electrolysis UV 0 25-100 101-500 501-1000 1001-3000 Population Served 3
Telemetry Monitoring of Filtration Plant Rio Piedras Community in San German, Puerto Rico 65 to 70 families (approximately 240 inhabitants) typical small rural community 4
Treatment Facility Components Intake Structure Horizontal Flow Gravel Filter (HFGF) Automated Valve Slow Sand Filters (SSF) Distribution Tank Slow Sand Filters Distributio n Tank 5
Telemetry Monitoring Instruments Intake Structure YSI 6920 sonde Tower with solar panel and data Node ( slave node ) with radio antenna. Distribution tank YSI 600 SL Sonde (inside the tank) YSI 6920 Sonde (effluent of the tank) 6
Main System and Remote Monitoring / Telemetry Components Solar Panel and Radio Tower Source Water Quality Solar Panel and Radio Tower Source water quality and Distribution Tank Water Level Data access node Dam ( 922 ft) Automatic Control Valve based on Source Water Turbidity Quality Sonde Source Water 0.52 miles HFGF (830 ft). SSF (810 ft) 0.77 miles 0.25 miles Distribution Network Distribution Tank (810 ft) A Water Distribution Tank 7
Data 8
Filtration System profile Advantages high quality water Gravity based No power consumption No pumping needed Disadvantages high initial capital cost 9
New Drum Filtration Systems Alow cost method of filtration and disinfection to produce microbiologically safe drinking water for smaller rural communities Initially constructed and tested at EPA T&E facility in Cincinnati, Ohio. 10
Experimental Drum Sand Filters Installed to the water treatment facility in the village of Las Piedras Located on an area below the SSF and are fed from a tap installed in the line running from the HPGF to the SSF The discharge from the ESF units is routed to a drain line that has been installed and directed to minimize erosion impacts at the site 11
Main Components 3 polyvinyl chloride (PVC) filter backwash distributors 6 2 actuated ball valves 6 ½ actuated 3 way valves 3 55 gallon steel drums 3 55 gallon drum lids with fittings 2 YSI flow through cells and sondes 1 tablet chlorinator 1 98 Amp hr battery 1 liquid chlorinator Sand 1 solar panel Chlorine bleach and chlorine tablets 2flow meters 12
Drum Filters Configuration 3 drums assembled in the same manner 55 gallon steel drum filled with a greater depth of finer sand filter material supported by two layer of coarse sand MEDIA SIZE Sand Global No. SS 6/20 (coarse) Sand Global No. SS 20/30 (medium) Sand Global No. SS 30/65 (fine) TOTAL SAND (KG) 67.8 135.6 67.8 13
Drum Filters Configuration Series Configuration (actual arrangement) 2 drums filtrating in succession, one on standby The effluent of the first drum is the influent of the second Parallel Configuration 2 drums filtrating at the same time one on standby Separate influent, combined effluent Backwash sequence One drum enters standby after 6 minutes of backwashing Standby drum is alternated every 2 days and 8 hours 3 time a week 14
Troubleshooting Control box/ backwash sequence Improve of power system Generated by a combination of solar panels for a total of 50 watts A power relay timer was added to minimize power consumption 15
Site Monitoring Parameters measured: Dissolved Oxygen in (mg/l) ph Specific Conductivity in μs/cm Temperature in C Turbidity in NTU Chlorine (mg/l) Bacteriological count 16
Monitoring: sampling ports 2 Port Water 1 Pre filtered 2 Pre chlorinated 3 Drumseffluent 4 Post chlorinated 5 Slow Sand Filtered Water 6 Backwash effluent 1 Legend: Sampling Port 3 4 ½ inch pipe 5 6 2 inch Backwash pipe
Results: Drum Influent and Effluent Dissolved Oxygen (mg/l) 7.3 7.2 7.1 7 Influent (Port 1) Effluent (Port 4) ph 8.5 7.5 6.5 Turbidity (NTU) 0.3 0.25 0.2 0.15 0.1 0.05 0 MCL Dissolved Oxygen Increased ~ 2% Turbidity Increased ~ 50 % ph Increased ~ 2 % EPA Maximum Contaminant Level (MCL) Turbidity: may never exceed 1 NTU, and must not exceed 0.3 NTU in 95% of daily samples in any month ph : 6.5 8.5 DO : Concentration above 5mg/L support aquatic life 18
Turbidity (NTU) Results: Backwash Influent and Effluent 8 6 4 2 0 14 Dissolved Oxygen (mg/l)10 12 10 8 6 4 2 0 A B C A B C ph 8.5 7.5 6.5 A B C Backwash Inlet (Port 5) Backwash Outlet (Port 6) Dissolved Oxygen Increased ~ 15% Turbidity Increased ~ 200% ph on drums B&C increased but on A increased A: Results from drum A B: Results from drum B C: Results from drum C 19
Drum Bacteriological Background The method used was the membrane filtration With a 45 mm membrane diameter and a 0.45 µm size Total Coliforms Gelman m Endo broth which targets total coliforms Incubated for 24 hrs. @ 35 C Fecal Coliforms Hach m FC broth that detects fecal coliform Incubated for 24 hrs @ 45 C Heterothrophic plate count (HPC) Uses Triptic Soy Broth (TSB) cultivates HPC. Incubated for 72 hrs (3 days) @ 35 C 20
Drum bacteriological EPA rules Less than 500 bacterial col/ml 21
Drum bacteriological Min Aveg Max 3.6 16 TMTC Min Aveg Max 0 1 1 0 5 8 3.6 14 TMTC 0 1 1 Min Aveg Max 8 21 TMTC Port Water 1 Pre filtered 2 Pre chlorinated 3 Drums effluent 4 Post chlorinated 5 Slow Sand Filtered Water 6 Backwash effluent Legend Sample (Col/mL) Total Coliforms Fecal Coliforms 1 4 11 23 0 1 1 2 1 4 TMTC 3 4 5 6 Min Aveg Max 0 4 7 0 1 1 (HPC) Min Aveg Max Min Aveg Max 0 0 0 4 4 4 2 29 56 0 0 0 4 4 TMTC 0 1 1 20 24 29
Chlorination system Liquid chlorinator (Pre chlorinator) Initially injected solution of 0.095% Sodium Hypochlorite Clorox Increased to Inject solution of 0.19% Sodium Hypochlorite Clorox to minimize bacteriological count inside the drums Chlorine concentration entering to the drums on average: Free chlorine: 0.40125 mg/l Tablet chlorinator (Post chlorinator) Addition of PVC spacer to decrease concentration of chlorine in the effluent water Low bacteriological count High concentration of chlorine in the effluent water 23
System Benefit Drums Online Filtration Flow rate (GPM) Time Operated (min) Volume Filtered (Gal) Backwash Flow rate (GPM) Backwash Time (min) Volume Backwas h (Gal) Net Treated Water (Gal) 1 1 1048320 1048320 4 2808 11232 1037088 24
System Benefit Drums Online Filtration Flow rate (GPM) Human Consumpt ion per week (Gal) Humans Attended Per week Cost of System ($) Cost of gallons of treated water ($/gal) 1 1 88452 12 14457.7 0.013941 Cost High/Actual $14457.7 Cost Med $2142.05 Cost Low $1248.5 25
Conclusions Solution to the problem of filtration for those small rural communities receiving water from surface sources in P.R. Demonstrated that innovative drum filtration system is a viable alternative for small rural communities that complied with the regulations. 26
Future Work Find effective optimum for chlorination Construct a retention tank for chlorine Analyze the by products from chlorination Analyze for Cryptosporidium and Giardia lamblia. Increase flow rate in the drums to yield more treated water volume Series or Parallel configuration, parallel inlet and series effluent to increase flow rate Pre gravel drum filter or coarser media to water inlet Find a lower cost effective and more simpler system to deploy in a rural low resource community. 27
Acknowledgement Advisor Professor: Dr. Sangchul Hwang, PhD, P.E Dr. Ivonne Santiago, PhD Environmental Engineering Laboratory team Rajib Sinha, P.E at Shaw Environmental Group, Inc. U.S Environmental Protection Agency (EPA) Right Way Environmental Contact Information Dr. Sangchul Hwang (787) 832 4040 ext 3454 shwang@uprm.edu 28
Questions/Suggestions 29