Entrance Tank with flat plate LFOM for flows larger than about 60 L/s

High flow rates require large diameter pipes that are both expensive and difficult to install. An alternative would be to use a flat plate LFOM and use a masonry connection between the entrance tank and the flocculator. The goal is to create an alternative design for the entrance tank that uses a flat plate LFOM.

Backwash Recycle

Backwash water, floc hopper waste, and water that is wasted during treatment failures must be managed. Given that water is often in short supply it makes most sense to allow this water to settle and then recycle the slightly clarified water back to the front end of the AguaClara plant. Design a system that uses a minimum number of pumps and that is easy for the plant operators to manage. Size any tanks and pumps and add them to the design for plants in the size range of 10 to 80 L/s.

High flow Chemical Dose Controller (CDC)

Design a CDC for flows above 100 L/s.

• Determine when a larger float valve is required for the constant head tank and locate an appropriate option.
• Design a method to generate laminar flow in a single large diameter transparent pipe by inserting smaller round, square, or hexagonal tubes inside the pipe. Propose a method to design and fabricate this system and select materials that are chlorine resistant.
• Design the plumbing for the coagulant from the constant level tank to the place where the coagulant is injected below the LFOM.

Compact Inlet manifold

Manifolds need to have a higher velocity in exiting jets of fluid than in the pipe so that the effect of pressure recovery in the pipe doesn't cause extreme variability between the first and last port flows. This constraint is a problem for the sedimentation tank inlet manifold because the velocity exiting the diffusers must be kept low to prevent flocs from being broken. The low exit velocity results in a low pipe velocity and that requires an expensive large diameter pipe. Filter underdrain systems encounter a similar constraint and often use a second flow passage for flow equalization between the main manifold pipe and the ports.

Another strategy would be to have the ports act like pitot tubes so that flow through each port is pushed by both the pressure and the kinetic energy of the flow. The challenge with this approach is that the many closely spaced ports required for the jet reverser system are too close for the flow in the main manifold pipe to fully expand between pitot tube ports.

These two strategies could be combined by using a pitot tube system to transfer flow from the main manifold pipe to the second flow distribution chamber. This flow distribution chamber could be created by inserting a plate in the manifold pipe that would run the length of the manifold pipe with pitot style ports transferring flow from the main manifold pipe to the flow distribution chamber.

The flow distribution manifold needs a full hydraulic design to size the pitot tube ports and the relative dimensions of the primary and secondary flow chambers. The hydraulic design and the CAD design will need to be tightly coupled and the design will undoubtedly be iterative as it accounts for fabrication and hydraulic constraints.

Design an AguaClara plant on a skid (containerized for transport by tractor trailer) for deployment in the US

This is a task that could be split into several subtasks and divided between several teams.

• 10’ x 40’ container plant
• Design a compact AguaClara plant in a container. Consider fold out walkways and a tent style roof. This would be for the US market and for rapid deployment.
• Develop a strategy to build the plant using a combination of PVC with an exoskeleton of perhaps aluminum or steel.
• A supporting task for this challenge would be to create a PVC tank feature that is similar to the civil tank feature.

Selectively dump old flocs

Our goal is to modify how flocs are dumped from the primary filter (floc blanket) to the floc hopper. We hypothesize that flocs in the primary filter have a finite capacity to capture incoming particles because particles are captured inside the floc the porosity of the floc decreases, less water flows through the floc, and fewer particles are captured by the floc. Ideally the floc dump system would select for flocs that have reached their particle capture capacity. Currently we extract flocs from the very top of the floc blanket and they flow across the weir into the floc hopper. New flocs that just came from the flocculator are captured by the plate settlers where they settle to a surface, tumble together down the incline, grow into larger flocs, end up in the primary filter as the best floc filters. Given that those flocs are entering the floc blanket from above and given that those new flocs are the lowest density because they haven't yet captured lots of particles inside their pores, it makes sense that new flocs are at a higher concentration at the top of the primary filter and the spent floc concentration is higher at the bottom of the primary filter. Thus it would be better to dump flocs from the bottom of the primary filter rather than from the top.

Design a chimney that uses the head loss through the floc blanket to drive flow through the chimney that then dumps into the floc hopper.