Challenges Fall 2009

Please read through this list before ranking your preferred teams. Don't worry if you're not sure what everything means. Returning team members, Monroe, Julie, Matt, and Heather will be more than happy to get you up to speed. Just use this as a guide to see generally what kinds of things the teams are working on. Check out each team's page on the wiki for a more basic description of what they do and to see what work they've already accomplished.

Design

Subteam Leader: Heather Reed

Number of team members needed: 9-10

Important team member skills:

• CEE 3310, or equivalent Fluid Dynamics course
• CEE 4540 co-requisite
• Students must be comfortable with coding
• Students should be familiar with the AguaClara design
• AutoCAD and/or MathCAD knowledge is a plus
• We are willing to train new members

Challenges

Design support for the APP/AguaClara team in Honduras

Review the Agalteca design and make sure that design improvements created since May of 2009 are incorporated in the design

• Eliminate floc hopper
• Add weirs at the end of the inlet and exit channels
• Add a drain line to the exit channel (it won't be possible to drain the exit channel with the weir in place unless we add a new drain line)
• Add a removable drain port in the bottom of the sed tank to facilitate cleaning
• Consider making the bottom of the sed tank have a steeper slope to facilitate cleaning of the distribution tunnels
• Consider making the sludge drain have fewer orifices that are then larger in diameter (perhaps eliminate half of the orifices)
• Set the maximum energy dissipation rate at the end of the flocculator to match the maximum energy dissipation rate at the end of the Marcala flocculator. Refer to the CEE 4540 notes on Flocculation

AguaClara Design Tool (ADT)

• Check that all pieces are scaling properly
• Identify design errors and work with the team in Honduras to develop improved design algorithms
• Update the list of variables that are returned to the user to ensure that all relevant parameters are returned.
• Eliminate variables in the Variable Naming Guide that aren't used.
• Develop a protocol to release new versions of the ADT. Begin by developing a method to create a stable release of the MathCAD files. Also develop a testing protocol that will use an independent check to verify that the plant dimensions are correct before releasing a new version.

Chemical Doser

We are currently switching from the linear flow orifice meter (LFOM) and laminar flow controller to a submerged orifice flow meter and orifice based flow controller.

• Need to develop AutoCAD code to draw this part of the plant
• Need to develop the design algorithms for the orifice based dose controller

Entrance tank

• A first draft of this code has been created, but it has not yet been reviewed.
• The Rapid mix and Chemical Doser needs to be drawn in the entrance tank.

Rapid mix components

The rapid mix design algorithm has been updated in the past year and consists of macroscale mixing followed by microscale mixing. The macroscale mixing could be a simple inline static mixer. The alum must be injected (through a submerged injector) immediately upstream from the inline static mixer. The microscale mixer is a submerged orifice at the bottom of the dividing wall between the entrance tank and the flocculator. This orifice is designed to have approximately 50 cm of head loss since it is this head loss that will also be used to measure the plant flow rate and drive the chemical dose controller. A PowerPoint presentation on the rapid mix process is available from the CEE 4540 syllabus.

This task should begin with a manual drawing showing how the rapid mix unit, entrance tank, flocculator, and chemical dose controller would fit together. After that drawing is reviewed by Monroe and by Agua Para el Pueblo staff it the MathCAD to AutoCAD (MtA) code can be written.

Chemical storage tanks

• These tanks need to be drawn. These may be an item that the onsite civil engineer will relocate to fit site conditions, but the design tool should show them at the correct elevation and in a reasonable location.

Floc Hopper Drain Valves

• The floc hopper can be put on hold for this semester because we haven't been able to create a floc blanket in a full scale AguaClara plant. This task can wait until we develop a method to create a floc blanket.

Horizontal Flocculator

Continue coding the flocculator to include the option for horizontal flocculation for large plants and determine the flow rate for the transition from vertical to horizontal flow.

• Document and describe the solution algorithm for the vertical flow flocculator
• Design a horizontal flow flocculator and develop a clear algorithm for the solution process (see Flocculator PowerPoint from CEE 4540)
• Create the equation or system of equations that will determine whether a design will have a horizontal or vertical flow flocculator. The minimum flow for a vertical flow flocculator will be related to the minimum channel width given a channel width that is about 3 x the baffle spacing and the requirement that the baffle spacing be at least 45 cm for constructability.
• Develop a method to design both horizontal and vertical flow flocculators.
• Code the necessary drawing algorithms. Make the flocculator code as generic as possible to be able to handle both vertical and horizontal flocculators.
• Design and draw the drain system for horizontal flocculators.
• Determine if the client should be able to choose the flocculator depth (as independent from the sed tank depth) or if the client should be able to choose a design for either a vertical or horizontal flow flocculator.
  • If the client chooses horizontal or vertical flow, then the ADT would design for a depth equal to the sed tank when possible, but would design shallower floc tanks for small flows if horizontal flow is selected.
  • If the client chooses the flocculator depth then the ADT should default to horizontal flocculator design whenever possible to eliminate the problem with the drains.

Vertical Flocculator

• Need to ensure that the size of the ports between channels does not exceed the size available on the floc tank wall. Also, ensure that the spacing of the baffles in the last channel does not force them into the exit channel space (this may be taken care of by switching to horizontal flow).
• The drain system for vertical flow flocculators that are large enough that the baffles are ferrocement needs special attention. Given that the Marcala plant performs better than any of the other AguaClara plants and given that the Marcala plant uses ferrocement baffles with small ports at the bottom of the lower baffles, it seems reasonable to adopt the use of ports in the baffles for draining. This will require the use of the MathCAD code for draining tanks in series to choose the port size. Monroe has a version of this code. Code and draw the flocculator drain system. This drain system should only be drawn when the flocculator baffles are rigid and the flocculator is vertical. We need a method to determine if the flocculator baffles are rigid. One possible method would be to set a criterion based on the thickness of the baffles that the client specified.

Sedimentation Inlet and Exit Tanks

• The tanks at the end of the inlet and exit channels that hold the pipes leading to the distribution tank and to waste no longer need to be as tall as they are currently drawn. Rather they can just cantilever off the side of the sedimentation tank.
• The PVC pipe component that is embedded in concrete needs to be drawn as a PVC coupling
• The removable pipes that are connected above the coupling should be long enough that they reach the same elevation as the top of the sedimentation tank walls (include freeboard).
• The waste pipe leaving the inlet tank should be drawn as a Tee that connects to the waste line from the exit tank.

Sedimentation Tank Control Pieces

• The pieces that allow the sedimentation tanks to be shut off need to be drawn (caps for the inlet channels, and exit channels). In addition, the caps should have a 1" PVC pipe that extends above the surface of the water in order to prevent air being trapped in the pipes delivering flocculated water to the sedimentation tank, and also to serve as a handle for removing the caps.
• Design and draw the caps for the effluent manifolds that are used for refilling the sedimentation tanks with clean water after the tank is cleaned. The caps for this purpose have an orifice that is sized to fill the sed tank in as short a period of time as possible without using all of the plant flow.

Plant drain system

Most of the plant waste flows enter an open channel that runs along the end of the tanks corresponding to the end with the sedimentation tank entrance channel. The following items must be designed and then drawn.

• Drain channel built of concrete
• Drain valves for all the tanks (many are already sized, but none are drawn)
• Concrete covers for the drain channel with access ports

Materials List

This list has been started and needs to be edited with input from the engineers in Honduras. Calculate the following

• Total wall area
• Total tank plan view areas

Documentation videos

Create an AutoCAD video that will show the assembly of the plant with descriptions of each part. This video could serve as the documentation that gets sent to a client who designs a plant with the AguaClara Design Tool (ADT) that explains the technology behind each piece. This video will also be used for training and teaching. Ideally the video should be made using a series of commands based on the plant dimensions so that the video can be created automatically for different plant designs.

Scale model

Create a scale model of an AguaClara plant that can be disassembled to show maintenance operations and to show the water path. This scale model should be should be small enough that it can be easily transported.

Research

Tube Floc

The development of FReTA and the data processing methods used to analyze its measurements has given AguaClara a powerful research tool. The investigation by Ian Tse into fluid shear influences on hydraulic flocculation was the first of many studies that could be performed with the tube floc/FReTA apparatus.

*Extend the experimental range evaluated by Ian Tse by increasing the length of the tube flocculator. One of the goals of this research is to measure the effect of collision potential on the residual turbidity. We have preliminary evidence that the residual turbidity continues to increase as the collision potential is increased. The challenge is to determine how long that trend continues. Increase the total flocculator length by a factor of 2 and then by a factor of 3.

• Investigate tapered flocculation designs. Hydraulic flocculators in AguaClara plants are currently designed such that the energy dissipation rates incrementally decrease over the length of the flocculator. Begin with an experimental setup that has two energy dissipation rates and determine if there is any benefit. The energy dissipation rate in the second section of the flocculator can be independently controlled by using a peristaltic pump to remove a fraction of the flow. Thus the same size tubing can be used for both sections of the flocculator.

• Investigate the influence of microscale mixing. For these tests use a well designed flocculator that produces very low residual turbidity. It is unclear what influence rapid mix parameters have on plant performance. Compare performance of systems with no rapid mix to systems that have a high energy dissipation rate (of at least 1 W/kg). Measure the effects of changing the energy dissipation rate (perhaps 0.1 W/kg to 10 W/kg) and the residence time (1 s with a single orifice mixer to 100 s with a long small diameter coil) in the rapid mix unit.

• Measure the potential impact of poor macroscale mixing by adding approximately 10% of the turbidity AFTER the rapid mix process.

• measure the effects of the influent synthetic water compositions (particle type, particle concentration, introduction of organic acids, pH, alkalinity, etc.). For example, performing experiments with different initial turbidities can provide insight into how particle concentration affects floc strength and turbidity removal efficiencies. Likewise, varying the pH of the influent may help elucidate changes in floc strength as a function of pH. It is possible that floc strength (as measured by floc size) is well correlated with optimal alum dose and pH.

• A laboratory scale hydraulic flocculator that operates under turbulent conditions that are relatively homogeneous and easy to characterize could go a long way into understanding turbulent flocculation. Comparison of residual turbidity and floc sedimentation velocity from turbulent and laminar flow flocculators could be used to validate flocculation models. Design a turbulent tube flow flocculator by using a larger diameter tube. Determine the required flow rates and assess the capabilities of the temperature controlled water source and the peristaltic pumps to deliver the required flows. Design an upgrade to the experimental apparatus to deliver the higher flow rate if needed.

Plate Settler Spacing

Current Subteam Leader: Rachel Philipson

Number of team members needed: 3-4

Important team member skills:

• CEE 3310 or equivalent Fluid Dynamics course

Challenges

• Run experiments to characterize the conditions that cause floc roll-up
• Improve the Theoretical Analysis of the Velocity Gradient by including the Reynolds Number dependence on velocity and then solving fo the theoretically model and calculate the particle size that will roll up the tube settler
• Investigating the same effect of influent parameters such as natural organic matter, pH, and alkalinity on floc performance and plate settler performance
• Velocity gradient studies on an influent turbidity with natural organic matter

Chemical Dose Controller

Challenges for Fall 2009

Subteam Leader:

Number of team members needed: 4

Important team member skills:

• MathCAD
• Process Controller
• Fluid Dynamics

Challenges

Non-Linear Chemical Dose Controller

• Write the algorithms for the microscale mixing orifice that connects the rapid mix chamber to the flocculator for optimum energy dissipation, head loss, and float sizing. See the Rapid Mix for equations to size the orifice.
  • We have tentative results in the mathCAD file, however, we did not have enough time to optimize the functions created.

• Construct non-linear CDC and run experiments to evaluate design and ensure experimental results align with theoretical results.
  Evaluate the optimal

For additional challenges, see the suggested challenges our team did not address this semester.

Computational Fluid Dynamics (CFD)

CFD 3D Floc Tank Simulation Challenges for Fall 2009

Subteam Leader: (Wenqi has graduated, but can help with training new members)

Number of team members needed: 2~3

Important team member skills:

• Fundamental fluid mechanics
• Basic idea of flocculation mechanisms, easier to learn with fundamentals of fluid mechanics
• Rough idea about computational fluid dynamics or numerical methods, but not a must
• Previous experience with FLUENT is great, but not a must
• Basic programming skills, C is great but not a must at all (sometimes we will use C to write some user-defined-functions)

Challenges

The long-term goal of the CFD team is to help augment our understanding of hydraulic flocculator, and together with other research teams, to provide for a guideline for design and operation of hydraulic flocculators.

• More simulation for 2D performance parameter analysis: we had some encouraging results and possible future topics are:
  • Further analysis for the current data: change within one flocculator from baffle to baffle, etc.
  • Simulations with different Reynolds number
  • Other ways of varying the geometry: different numbers of baffles, baffle spacing, etc. encountered in design
  • Further develop the formulation of parameters
• Extend to 3D model:
  • Improve convergence, to which energy dissipation rate is very sensitive
  • Configuration of parallel computing for 3D simulations
  • Modify the mesh: check the regional convergence of the mesh, coarsen the mesh in some region
• Validation
  • Sensitivity analysis of other parameters when necessary
  • Find some experimental data to compare (or some better idea?)

Floating Flocs

Subteam Leader:

Tanya or anyone with previous knowledge of floating flocs problem

Number of team members needed:

• 3-4 members

Important team member skills:

• Process Controller (can be trained)
• Microsoft Excel
• MathCAD

Challenges

Details of the experiments that have been planned can be found on the Floating Flocs Fall 2009 Tentative Experiments page.

• Possibly redesign the experimental setup to better simulate the water quality at actual AC plants by adding a clay source or surfactant source.
• Confirm the cause of the floating floc problem by running experiments with the Plate Settler Team's apparatus. Two experiments have been planned in order to test whether the cause of the floating floc problem is bubbles adhering to flocs or whether bubbles form on flocs and lift them to the surface. It is also possible that both of these mechanisms are responsible for floating floc.

If the cause is confirmed to be bubble formation on or adherence to flocs due to supersaturated water the team's tentative experimental plans include:

• Run experiments using mild surfactants to witness their effects on bubble formation. Currently, the team is considering using a dilute soap solution as a surfactant. Details as to the concentration of soap solution have yet to be determined. This will likely be based on a conversion of organic matter in the water of AguaClara plants.
• Run experiments using hydrophobic surfaces with or without surfactants to see the effects on bubble formation. The details of these experiments have yet to be determined. Currently, literature searches are being performed to find cost-effective hydrophobic surfaces to test. It has been found that plant surfaces may exhibit hydrophobic properties due to their waxy coating.
• Developing a new mechanism to either remove gas, stop bubble formation, or stop floating flocs themselves. Currently, the team is looking at a mechanism that involves using lamella or something similar to trap air pockets in the water. These air pockets would be knocked around by eddies and may collect dissolved gas in the process.

One possibility to consider is whether flocs that are floating can be redirected or captured so that they are not in the effluent water. (I doubt this can be done.) Since achieving gas removal has been proven to be difficult, putting some time into considering other solutions may be worthwhile.

If the cause of floating flocs is shown to be something other than supersaturated water, the team may still focus on stopping flocs from floating; however, other approaches may be developed that are specifically tailored to actual cause of the problem.

Rapid Mix

The rapid mix research project's goal is to determine if inadequate mixing in the rapid mix unit is responsible for the residual turbidity at the end of the AguaClara treatment process. This can be accomplished by adding some additional turbidity after the rapid mix process to see if those colloids have a significant effect on the settled water turbidity. If a large fraction of the colloids that didn't go through the rapid mix end up in the effluent, then it suggests that colloids that aren't properly exposed to aluminum hydroxide in the rapid mix process could also end up in the effluent. The next phase of this research would be to experiment with different rapid mix designs.

• energy dissipation rates
• residence times
• sequence of mixing units where each mixing unit has an alum feed
  

Outreach

Fundraising

Group Leader:

• N/A

  Number of team members needed:

• Minimum of 2-3

  Important team member skills:

• Good written and oral skills
• Ability to work closely with P.R. when finding Fundraising Contacts
• Good analytical skills for choosing grants and reviewing previous budgets
• Adaptability to the different requests of different organizations when looking at Requests for Proposals (Grant Writing term meaning grant application)

Challenges

• Continue to raise funds for the Agalteca plant
• Assess the feasibility and if there are no obstacles, write a proposal to http://nciia.org/grants/sustainablevision. The proposal is due by October 16, 2009. The final draft should be completed at least 2 weeks before the deadline.
• Pursue contacts within Ford Foundation
• Submit the Ford Foundation Online Form
• Pursue contacts within Bill and Melinda Gates Foundation
• Analyze former AguaClara budgets for the budget update.
• Continue working on the Grant Text Modules Page.
• Update the Grant Short List as grants are submitted

Public Relations

Group Leader: N/A

Number of team members needed: 4-6

Important team member skills:

• Adobe Photoshop to aid graphics design
• Microsoft Publisher to create brochures and newsletters
• Effective communication skills
• Leadership skills
• Knowledge of advertisement, business, media communications
• Creativity and ingenuity
• Spanish language knowledge is a plus

Challenges

• Get more team members involved with presentations
• Create a fact sheet for presenter. Include additional AguaClara info that is not already on the slides
• demo plant suite case maintenance
• Edit the Outreach Wiki to eliminate outdated information
• Update the brochure with new projects
• Write a fall edition of the newsletter and send to the AguaClara googlegroup before Thanksgiving break.
• Enforce the standardized Wiki format by constant updating (not just at the end of the year)
• Assign specific subgroups within PR such that different types of PR can be accessed more efficiently. I.E possibly set up subgroups of PR that deal with local pr, state/national pr, campus pr, student assembly/RSO/Greek life.
• Broaden the medium for pr. I.E. radio, newspapers, magazines, journals, pamphlets, brochures, banners, t-shirts, stickers, posters, etc.
• Establish a calendar of pr events in August that seeks to promote the project itself while incorporating pr events that surround fundraising, presentations, etc.
• Draw in students from business, entrepreneurial majors, marketing, advertising, etc.