AguaClara Project Challenges Spring 2009
Team Leader: Nicole Ceci
Outreach Spring 2009 Challenges
Subteam Leader: Unknown
Number of team member needed: As many as possible
If more than 5 people join, subteams should be created
Important team member skills:
- At least one returning Outreach team member
- Experience with AguaClara is helpful, but this is a good team for new members
Challenges
Fundraising
Overview: In the Spring 2008 the Outreach team worked to make contacts to develop relationships for future funding and potential partners. The Fall 2008 Team took the opposite approach and devoted much effort toward applying for grants and creating the materials that would make it easier. The next Outreach Team needs to go back and reach out to the contacts made last spring through presentations, newsletters, and any other applicable means you feel would be effective. In the future we hope that communities will be able to outright buy an AguaClara plant based on their affordability. Until that day comes we rely on grants and donations to see us through. It has also been proposed that microfinance partnerships could benefit us, although it seems that it would be a direction that needs to be well research and thoroughly planned before implementation could occur. (See Business Team below)Specific challenges:
- Follow up with and maintain contact with organizations and contacts from both D.C. trips in Spring 2008 (another trip to DC?)
- Plan events to present to Alumni (Reunion, Cornell Clubs?)
- Apply to some grants
Awareness
Overview: Awareness ties in with both our fundraising and recruitment efforts. Our current awareness initiatives include the conferences we attend, the fliers, brochures, and posters we create, and the presentations we give. Awareness challenges include those that we already do, but a few new ones have been suggested.Specific Challenges:
- Continue with AguaClara newsletter (quarterly? electronically sent to all contacts/ potential donors/ aguaclara alumni etc.)
- Update AguaClara Alumni to include past semesters grads
- In the future ask students if they wish to be on the list serve for the newsletter.
- Finish the Demo Plant Instructions Manual, laminate for the suitcase, and make available on the wiki
- ESW Conference scheduled for Fall 2009, keep an eye out for any new deadlines or correspondance
- Lesson plan for local schools present about Honduras/water/aguaclara at local schools
- Organize trips/events for people to present
Recruitment
Overview: Recruitment initiatives continue to be based on Presentations to freshmen's Intro 1050 Classes. Other initiatives have included attempting to get CEE 255 crosslisted, so more non-engineering majors might enroll, but hasn't proceeded very far.Specific Challenges:
- Organize 1050 presentations, Host meetings open to class to go over using the demo plant and the presentation aka training for 1050 presentations
If you still think it's a good idea (less important than other challenges): - Get CEE 255 listed for interdisciplinary courses for the fall
- Work on syllabus for interdisciplinary purposes
Business Team?
If there is interest in creating a separate business team, it could be 2-3 members. Tasks (suggested by last spring team) could include:
- Need to decide grants/microfinance
- Microfinance proposal with help from someone with business experience
- Better projections of global demand
- Better generic public health statistics about the importance of water
- Follow up on contacts made by Larry Harrington...lots of contacts so figure out a way to reach more of them
- Learn more about microfinance specifically towards AguaClara
- Contact Engineering firms/Government Agencies about the potential for partnerships.
- Follow-up with SEA and figure out a strategy that can work for both groups to keep them involved
Linear Flow Orifice Meter Challenges for Spring 2009
Subteam Leader: Unknown
Introduction for New Members
In order to gain a firm understanding of the LFOM material it is necessary to review the posted material. The most important material is listed below
- The intial concept paper abstract, introduction, and design. Available here
- The LFOM Accuracy Experimental data, available here - This provides a practical view of the LFOM in operation
- The mathcad code should be thoroughly reviewed, available here
Number of team members needed: 1
The LFOM team is a one person team, with a narrow focus. It may be benefical to combine the LFOM team with the Linear Chemical Doser because interfaces between the two systems will be very critical.
Important team member skills:
- Strong background in Mathcad or at least some aptitude with computer programming
- Understanding of the fluids concepts would be beneficial, through courses such as CEE 4540 or CEE 3310
Challenges
- Currently the drill size is based on the diameter that is the best fit for the top hole, it would be interseting to see what the effect is on the error if different rows were used to determine the diameter. The very top hole has a relatively small flow rate based on other rows - there may be a critical row.
- Also the point of failure experiment was conducted and the results were contrary to the expected hypothesis. Instead of the LFOM working to a certain flow rate and then failing the flow rates were linear but with a different slope than the predicted values, information is available on the experiment page. The perplexing results may be due to the fact that there we were not witnessing a point of failure, a flow rate at which a LFOM will fail, but a complete failure. If the pipe is sized too small to accomodate the flow rate which the orifice pattern is designed to support then the LFOM will fail for all flow rates. This hypothesis would agree with the results. It would be beneficial in future research to test the LFOM created above with a diameter of 1.5 inches with an orifice pattern designed to handle the maximum flow rate for the pipe, 62.5 L/min. It would also be interesting to apply a flow rate in excess of the 62.5 L/min and watch the system for evidence of failure.
- Thirdly it is important to work on interface between the LFOM and the automated chemical doser.
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CFD Flocculation Tank Simulation Challenges Spring 2009
Subteam Leader: Unknown
Number of team members needed: 2 or 3
The team needs at least 2 people to be sucessful. Collaboration with peers helps solve coding and conceptual problems as they arise.
Training
It seems worthwhile to have a session with Wenqi (and other potential members) before winter break covering:
- automatic generation of scripts in GAMBIT
- UDFs in FLUENT
- methodology of modeling
Requirements for future members:
Knowledge of FLUENT, GAMBIT, UDFs and scripts is very important for members interested in modeling the flocculation tank. These skills can be learned by taking MAE courses such as intermediate fluid dynamics, or by taking self-guided training modules available online. Someone without a background in CFD will find it difficult to get up to speed in GAMBIT/FLUENT.
CFD 3D Floc Tank Simulation Challenges for Spring 2009
Subteam Leader: unknown
Number of team members needed: 2
Important team member skills:
- Comfortable with coding;
- Basic knowledge of fluid mechanics;
Challenges
- Appropriate mesh in 3D
- Mesh interval size and boundary layers
- Validate: Check grid convergence, etc.
- Define the model in FLUENT
- Turbulence model and other parameters
- Validation of the model
- Numerical stability: convergence, accuracy
- Compare with experimental data: find similar flows and related experimental data (free/confined jets, back step,etc. )
- Compare with 2D model: verify the assumptions and validity
- Automation of mesh generation and FLUENT setup
- Data/Parameter analysis and recommendations
- Recognize important variables and parameters
- Write user defined functions to extract analysis data
- Investigate the performance of different geometry
Floating Floc Detailed Task List
Spring 2009 Team members
Tiffany McClaskey
Ling Cheung
Tanya Cabrito
Haley Viehman
Wenny WuThis semester, it is imperative that we find a solution to the issue of flocs rising to the surface of the water in the sedimentation tank. The Marcala and Tamara plants are seeing a significant amount of particles rising to the surface. Our understanding is that the water is coming into the plants super-saturated with oxygen. Once the water enters the grit chamber and is under atmospheric pressure, bubbles of oxygen begin to form. Some of these bubbles attach to the sediment particles in the water, and flocs form around the bubbles that haven't left the water while in the grit chamber. Since bubbles form more quickly when they are attached to something (you may have noticed that your glass of faucet water develops bubbles on the sides), the proposed solution is to create surfaces on which the bubbles can form. Larger bubbles rise faster than small bubbles so the goal is to create the largest bubbles possible in the shortest amount of time. We will explore two methods to speed up the process of bubble formation: A) Seeding the supersaturated water with bubbles and reducing the pressure to less than atmospheric pressure to increase the driving force that is causing the bubbles to form; and B) Run the supersaturated water through a sand filter to provide ample surface area for dissolved oxygen accumulation and bubble formation.
Ideas for full scale implementation that we will be investigating at Laboratory Scale:
• Add air bubbles using suction through a small hole in the side of a down-flowing pipe right before the water enters the grit chamber. The additional air in the water will increase the bubble size as it joins the preexisting air pockets. The pressure in the pipe could also be maintained at a partial vacuum to accelerate the bubble formation process.
• Add sand to the bottom of the grit chamber simulating back-wash in a sand filter. The idea is that the dissolved oxygen in the water will form bubbles on the sand particles. Once the buoyant force is greater than the connection between the bubble and the sand particle, it will rise to the surface of the water.
• Add the equivalent of lamellas to the grit chamber. Bubbles will form on the underside of the lamella and eventually become large enough that they roll across the lamella surface and float to the surface of the water.
Two contraptions will be made that we will use to simulate different situations to help us determine the best course of action. The team will also be split into two subgroups so that each experiment can have the undivided attention of different team members. The members of each subgroup were decided based on class and work schedules. Tiffany and Tanya will be working on the aeration experiments and Haley and Ling will be focusing on the backwash sand filter. Wenny will be assisting each team interpret the data, contemplating other experiments that can be performed, attending meeting and assisting on written assignments.
MODEL 1: AERATION
Aerator Apparatus
The first will consist of a dissolved oxygen probe and a pressure sensor connected to a 4 inch PVC pipe with a suction outlet, a hole for influent water, an air stone and an air inlet line. To drain the system, the water inlet line can be detached over the sink at a valve that can be toggled shut near the source of the water. A partial vacuum can be maintained by pumping the air out of the cylinder via the suction outlet. The device also has a stir bar inside to help us model a complete mix system. As we adjust the pressure in the cylinder, the pressure sensor will allow us to know that the actual pressure is in the pipe. The DO probe will allow us to track the rate at which the oxygen leaves the water. The level of DO needed to keep the flocs from rising to the top of the sedimentation tank in the treatment plants has yet to be determined.Several different experiments will be conducted with this set-up. In order to simulate the water conditions in the pipes of the Honduras plants on a smaller scale, all experiments will be conducted with tap water that is supersaturated with oxygen.
Experiment 1 will be attempting to simulate what is happening in the pipe as air bubbles are being sucked into it. With the stir bar running, the dissolved oxygen level in the cylinder will be continually measured as different flow rates of air are pumped into the tube. This will be done with the lid securely attached to the top of the apparatus to make it air tight so we can add varying amounts of negative pressure in the pipe. The pressure in the pipe will depend on how high up from the outlet we put the holes through which air will be sucked into the pipe at the plants. By changing the pressure in the cylinder we are simulating different locations of the air holes.
With this experiment, we are seeking to measure DO levels as a function of time, pressure, and air flow rate. Using the pressure sensor and a rotameter, the pressure and air flow rate will be maintained throughout each test run and recorded. In addition to this, we will also be observing bubble size and recording the approximate average diameters of the bubbles. The clear cylinder will allow us to observe the growth and behavior of the bubbles.
The program written last semester will be used to determine the different air flow rates that will be used for the experiments. The program determines the amount of air that will flow through a hole under specific conditions, which depends on the size of the hole, the dimensions of the pipe and the flow rate of water. We can also f the likely pressure in the pipe for any given situation. This way we can model the plant in Tamara without having to reproduce the plant's high flow rate.
One of the drawbacks of this experiment is that it is basically assuming plug flow. The depth of the water in the PVC tube will hopefully be a completely mixed body of water but since we will not have the water flowing through the pipe the setup will imitate what is happening to the water in a 10 inch section.The length of each test run will be determined once we have the experimental device working. We currently do not know the kinetics of the bubble formation and thus we do not know how long the batch tests in the pressure/vacuum chaber will need to be. The data will be evaluated based on the level of dissolved oxygen in the water and how big the bubbles are. The goal is to determine the pressure and air flow rate that produce the biggest bubbles and lowest DO level. This should help us determine the optimum orifice size and its height above the outlet of the pipe.
Experiment 2 will model the interface between the pipe that is under negative pressure and the grit chamber that will be under atmospheric pressure. After air has been pumped into the sealed PVC pipe that is under negative pressure for a period of time (yet to be decided), we will turn off the inlet air and remove the lid to the device, exposing the water to atmospheric pressure. The dissolved oxygen level in the water will be continually measured one inch below the surface on the water as well as at the bottom of the cylinder. We hope to see more bubbles form and rise to the surface once the water is exposed to atmospheric pressure. This should help us determine the rate at which the dissolved oxygen level in the water will decrease under varying air flow rates and initial pressures. This will in turn suggest the retention time needed in the grit chamber to decrease the DO to an acceptable level.
We will measure DO levels at the top and the bottom of the water column as a function of exposure time for each pressure and flow rate tested. We will also observe bubble size, average bubble diameters, and note any changes in the behavior of the bubbles under atmospheric pressure.As in the first experiment, the length of each test run will be determined once we have the experimental device working. The data will be evaluated based on the level of dissolved oxygen in the water and how big the bubbles are. The goal is to determine the exposure time and air flow rate that produce the biggest bubbles and lowest DO level. This should help us determine the optimum orifice size and retention time in the grit chamber.
MODEL 2: BACKWASH SAND FILTER
This experiment will model the effect that running water through a layer of sand will have on its dissolved oxygen content. We hope to see that the sand particles facilitate larger bubble formation by providing surfaces to which small bubbles can adhere and grow until they are large enough to float to the surface. If the method proves to be effective, we can implement this in current and future AguaClara plants by transforming the grit chamber so that water enters at the bottom and flows upward through sand. Through experimentation as well as extensive literature searches, we hope to see the effects of the water's upward flow rate, the sand particle size, and the sand layer depth on dissolved oxygen levels. With this data, we plan to determine the optimum conditions needed for dissolved oxygen removal.
Our experimental set-up consists of a 63 cm glass column with an inner diameter of 2.5 cm, with caps for each end that allow water inflow and outflow. We will fill the tube partially with sand and send super-saturated tap water through the tube in a continuous flow (tapwater pressure should be sufficient). The flow will be large enough to suspend the sand particles, as though backwashing a sand filter. Water and any air bubbles that form will flow out of the tube at the top to a collection container open to the atmosphere, where will place the DO probe. The DO probe will monitor the dissolved oxygen content of the out-flowing water to help us determine the effect of the sand filter on dissolved oxygen levels.
The data from both models will be compared to decide which method would be the best for each individual plant. Which, if either, system to be used for each AguaClara water treatment plant will depend on the current configuration of the existing plants, the ease of retrofitting these grit chambers, the retention time in the grit chambers and the plant flowrate. The evaluation will be based on the method that can reduce the DO content the most, the retention time needed to achieve the optimal DO content and practicality of implementation. If neither method is seen to be fit to eliminate the occurrence of floating floc in the sedimentation chamber other options will be explored.
We currently have that materials required for the experiments detailed above.Challenges for Flow Controller Chlorine Precipitation Spring 2009
Subteam Leader:
Number of team members needed:
Important team member skills:
Challenges
- Keep in touch with John and Tamar about the progress of the communities that have implemented our recommendations about addressing the precipitation problem.
- If problems persist, we recommend the addition of a settling basin located between the stock tank and the constant head bottle. The settling basin would consist of a nalgene bottle with two bulkhead fitting located approximately half way up the height of the bottle. The bulkhead fittings would direct flow parallel from a tube, into the bottle, and then out the other side. Ideally velocity would decrease inside the bottle and some of the precipitate would settle out.
- If none of the other suggestions are effective, we recommend adding HCl to the solution to lower the pH, and inhibit precipitation of calcium carbonate.
Flow Controller Linearization & Calibration Challenges Spring 2009
Subteam Leader:Unknown
Number of team members needed: 1-3
Important team member skills:
- Knowledge of data aquisition software
- Medium level understanding of fluid mechanics
Challenges
- Verify the possibility of internal deformation causing head loss within the tube
- different tubing diameters- how is the flow affected by different tube sizes? and is there still divergence from the equations in large diameter tubing?
- Non-negligible losses- Minor losses with major effects may be accumulating in the tube due to constant bending and are causing an accumulated substantial head loss. Due to internal deformation, should major losses be considered?
- Early transition to turbulent flow- induce turbulent flow to better understand the upper bound of the design technology
- Is the flow control device feasible in the turbulent range?
- Is there any benefit to pushing the technology to higher and higher laminar flow rates?
- What is the viability of a dual dosing system or using a dosing tube which expands to control flow?
Plate Settler Spacing Challenges for Spring 2009
Subteam Leader: Sarah Long/Colette Kopon
Number of team members needed: max 3
Important team member skills:
- Fluid Dynamics background
Challenges
System
- Make the system more robust
1. Improve the tube settler connection
2. Stabilize the tube flocculators
Experiments
- Jet dissipation
1. Run experiments using a mesh with 1 cm diameter holes
2. Run fluid mechanics experiments to determine the rate of jet dissipation with the cone
- Tube spacings
1. Vary flow rates with each tube size
2. Varying Floc blanket height
3. Vary alum dosage
Process controller
- Use process control incremental method for varying flowrates with each tube spacing
- Set up a system that allows comments to be made without collecting data twice in process controller
- Develop some sort of video recording system to monitor floc blanket growth
Challenges for Spring 2009 Pilot Plant Team
Team Members:
Jeff Katz (jak232)
Art Shull (avs32)
Eladio Lopez (el447)
Rustom Meyer (rlm56)
Michael Liu (ml627)Important team member skills:
Returning Members
- Familiarity with Aguaclara Project
- CEE 4540
It would be helpful to have a "handy" person on the team that feels comfortable using power tools to do stuff. (Not super complicated work, just some comfort).
Challenges
Floc Tank
- Team members should test consecutive alum doses in order to familiarize themselves with the tank and floc formation
- Compare uniform and non-uniform baffle configuration results from the flocculation tank with high incoming turbidity
Tube Flocculator
- Alter the tube flocculat set-up to minimize air trapped from joints and it has a more permanent location at the plant.
- Set up FReTA to be used with the tube flocculator
- Use FReTA to compare settling velocities at different points in the tube flocculator
- Compare raw water readings from the Pilot Plant FReTA with the laboratory results
Sed Tank
- Discover how much time it takes to form a sludge blanket.
- Can a sludge blanket form if the lamella are present? Can the lamella be designed differently so that this is possible?
- What is the best way to drain a sed tank so as to cause the least amount of distrubance and water waste. How often would this need to occur?
- What else could be done to optimize the sed tanks?
- Are the two sed tanks equal? Is the tank turbidity comparable? Are flocs remaining equally intact from the flocculator to the tanks?
Goals
- Familiarize new members with plant and plant processes
- Get the plant up and running without leaks and problems
- Design and build new, robust baffle system
- Install a dose controller to vary alum dosing linearly with plant flow rate
- Make Process Controller remotely accessible so alum dose can be changed off-site
- Take turbidity profiles of the flocculator under different arrangements, including tapered and non-tapered baffle spacing
- Set up FReTA to be used with the tube flocculator
- Use FReTA to compare settling velocities at different points in the tube flocculator
- Compare raw water readings from the Pilot Plant FReTA with the laboratory results
- After completion of flocculation goals, sed tank research will commence