Challenges Fall 2009

Design

Challenges for Fall 2009

Subteam Leader:

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 Tool

• 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 VNG that aren't used.

Chemical Doser

• Need to develop AutoCAD code to draw this part of the plant
• Need to develop the transition from linear dose controller to nonlinear dose controller

Entrance tank

• A first draft of this code has been created, but it has not yet been reviewed.

Rapid mix components

Requires review and possible upgrade to the first draft of the rapid mix design and then coding of the MathCAD to AutoCAD (MtA) code.

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

• Now that the floc hopper has been drawn, we need to code and draw the valves that dumps the flocs from the floc blanket to waste.

Horizontal Flocculator

• Need to continue coding the flocculator so change to horizontal flocculation and determine when this transition should occur.

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).

Flocculator Drain System

• Need to code and draw the flocculator drain system.

Sedimentation Inlet and Exit Tanks

• The tanks at the end of the inlet and exit channels that hold the pipes leading to the distribution tanks and to the 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. Also the pipes in these tanks that lead to waste should be drawn as Tee's that connect to one another and then lead to waste.

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.

Material's List

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

Documentation

• Continue the effort to 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 user who designs a plant with the Design Tool that explains the technology behind each piece.
  

Tube Floc

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

Results of this study suggest several directions for future research into fluid shear influences on hydraulic flocculator performance. Present results clearly show that shear induced breakup significantly affects both the mean floc size and residual turbidity. Steady state floc sizes were observed at high velocity gradients, but not at low velocity gradients. Perhaps extending the length of the tube flocculator to twice or even three times the current length will provide new insights on how floc sizes and residual turbidities are affected at low velocity gradients.

Additionally, an investigation into the utility of tapered flocculation designs should be performed. Hydraulic flocculators in AguaClara plants are currently designed such that the energy dissipation rates incrementally decrease over the length of the flocculator. The present study showed that while the influences of shear induced breakup was evident early on in the flocculator, floc sizes were not nearly as limited by shear as they were later on in the flocculator.

Different influent synthetic water compositions (particle type, particle concentration, introduction of organic acids, pH, alkalinity, etc.) should also be tested to see how they affect hydraulic flocculation. 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 is well correlated with optimal alum dose and pH.

There are also questions regarding the role of rapid mix and how it affects flocculation. Do changes in the energy dissipation rate in the rapid mix or in the first stage of flocculation affect the final floc sedimentation velocity and residual turbidity?

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.

Plate Settler Spacing

Challenges for Fall 2009 and Beyond

Current Subteam Leader: Rachel Philipson

Number of team members needed: 3-4

Important team member skills:

• Fluid Dynamics Background
• Self-motivated
• Curious student
• Eager to learn

Challenges

• Run experiments to test floc roll-up

• Continue investigating the velocity gradient by varying the floc density and plate settler spacing

• Develop a way to 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

• The effects of biological flocs

• Continue to investigate the filter foam

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 CDC

• Determine whether a single or multiple orifices should be used to connect rapid mix chamber and flocculation for optimum energy dissipation, head loss, and float sizing.
  • 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.

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

Computational Fluid Dynamics

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-function)

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,that encoutered in design
  • Further develop the formulation of parameters
• Extend to 3D model:
  • Improve convergence, to which energy dissipation rate is very sensitive
  • Congifuration 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

Challenges for Outreach Fall 2009

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

• Submit the Ford Foundation Online Form
• Pursue contacts within Ford Foundation and 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
• Adobe Illustrator to create brochure layout
• Effective communication skills
• Leadership skills
• Knowledge of advertisement, business, media communications
• Creativity and ingenuity

Challenges

• Get more team members involved with presentations
• Try to pull together a fact sheet for presenter. Those would be good additional info to present other than the ones already on the slides. 
• demo plant suite case maintenance
• Edit the Wiki to weed out outdated information
• Update the brochure with new projects
• Ensure continued bi-annual updates through newsletters
• Enforce the standardized Wiki format by constant updating (not just at the end of the year)
• Translate Wiki into Spanish including navigation menu as well as content
• 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/ sports team pr.
• 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.
• Integrate the PR team with the AguaClara student group by establishing it as a subset of the group itself.
• Work with Partnership for Honduran Health on campus to continue planning their health survey of our technology.