Floc Probe - Fall 2014

Surya Kumar, Larry Ge

Abstract:

The sedimentation tanks at AguaClara sustainable drinking water treatment plants are performing well, but they can perform better. When floc settles it becomes sludge. If there is sludge buildup in a sedimentation tank, a host of problems follow: uneven water flow through the sedimentation tank, impaired performance, anaerobic digestion, and methane production. However, if a sedimentation tank can be designed to prevent any flocs from settling, then the drinking water treatment process will never have to be stopped, and the sedimentation tanks will never have to be cleaned. AguaClara is investigating the creation/use of a “Floc Probe” to better understand floc behavior and achieve this improved tank design. The research tool will be used to survey currently functioning sedimentation tanks in Honduras to identify where sludge is building up. Sonar has been found to be a potential solution. Sonar can detect substances of varying densities as well as record at what depth the substance was found. This technology can therefore distinguish between flocs and sludge, and can also recognize the amount of sludge buildup.

High Rate Sedimentation - Plate Settlers, Spring 2016

Albert Cheng, Sidney Lok, Yuqi Yu, Lishan Zhu

Abstract

This semester, the goal of the High Rate sedimentation - Plate Settlers team was to maintain a suspended layer of colloidal particles (flocs) at upflow velocities higher than 1 mm/s. The suspended layer, referred to as the floc blanket, circulates flocs, enhances flocculation, and is self-cleaning. As the floc blanket grows in height, it spills over a weir into a sludge collection chamber to prevent sludge build-up inside the sedimentation tank. increasing the upflow velocity in the sedimentation tank decreases the necessary plan-view area and cost of construction. A high density floc blanket is necessary to prevent flocs from escaping the sedimentation tank at higher velocities. The High Rate Sedimentation - Plate Settlers team explored different plate settler geometries in the sedimentation tank to concentrate the floc blanket.

High Rate Sedimentation (Floc Blanket), Spring 2016

Ogechukwu (Oge) Anyene, Isha Chaknalwar, Josiah Hinterberger, Ziwei (Vanessa) Qi

Abstract

The High Rate Sedimentation - Floc Blanket team built a sedimentation tank model with the goal of increasing the upflow velocity and decreasing the plan view area, without degrading the performance of the floc blanket inside the tank reactor. Under high turbidity conditions, a stable floc blanket was maintained under upflow velocities from 1-4 mm/s. Two method of encouraging floc re-circulation, viz., in-reactor lamella plates and sludge recycling, were tested to observe effects on effluent turbidity. Results indicated that neither method had a strong enough effect to fully recommend increased upflow velocity, but future testing in improved apparatus with low turbidity influent has potential.

Milli-Sedimentation Fall 2016

Jillian Whiting, Tianyi Wang, Janak Shah

Abstract

The goal of the milli-sedimentation team was to find and explore the boundaries between sedimentation and filtration which could be used to reduce the size and residence time of AguaClara plants. The technology was designed using coffee straws that are sized between the spacing of plate settlers (10 mm) and the porosity of filter material (0.1 mm). The size of the plant would be on the scale of a small town or village, less than 1000 residents, replacing what the foam filter did in El Carpintero. One of the biggest challenges for the semester after building the sedimentation-filtration system was attempting to clean the apparatus, as this determined the feasibility of the design.

High Rate Sedimentation - Summer 2017

Christopher Galantino and Andrew Kang

Abstract:

The High Rate Sedimentation team designed, fabricated, and experimented on various sedimentation designs with an upflow velocity of 3 mm/s while maintaining a efficient effluent turbidity and reducing cost and space. Working off where the Spring 2017 team left off, the HRS team continued to research the effects of floc blanket height, tube settler length, varying geometries, and the size-driven floc blanket formation hypothesis. The HRS team concluded that the height of floc blanket may not provide better performance, as originally thought. Also, it has been concluded that the Trapezoidal geometry is not necessary, but provided insight on the behavior of floc on bends.

High Rate Sedimentation - Fall 2015

Oge Anyene, Larry Ge, Yuqi Yu

Abstract:

The Fall 2015 High Rate Sedimentation team aims to design a new sedimentation tank that will allow the tank upflow velocity to be significantly increased (by a factor or 2 to 10), without sacrificing particle removal performance (no increase in effluent turbidity). The motivating factors behind this velocity increase would be to decrease the plan view area of the sedimentation tanks, leading to smaller plants and lower the construction costs and to decrease the overall hydraulic retention time of the plant. One of the primary objectives of the new sedimentation tank will be to maintain a consistent floc blanket (i.e. one that allows for excess floc drainage into a floc hopper) similar to the ones found in current AguaClara plants, even with the increased upflow velocity. In order to achieve this goal our proposed design will feature two sets of plate settlers, one set near the bottom of the tank that will be suspended within the floc blanket, and one above them to capture finer particles. To test the feasibility of such a design, several small-scale experiments will be run in the lab. Such experiments will prove to demonstrate whether or not it is possible to maintain a fluidize bed within plate settlers and what the bulk flow of flocs will look like for a floc blanket maintained within plate settlers.

Fabrication: Floc Hopper Probe - Spring 2016

Miguel Castellanos

Abstract:

The floc hopper probe is a devise that is meant to locate the height of the sludge blanket in the floc hopper of AguaClara water treatment plants. Teams in the past have conducted research and eventually fabricated a working probe prototype that was transported down to Honduras in January 2016. The probe was tested at different treatment plants in Honduras and showed promising results with minor complications. This semester, one of the main objectives is to re-size the probe in order to ensure that it is able to enter the PVC pipe port that is in the sedimentation tank channel system. Furthermore, the team will look into making the design more professional while keeping it cost effective.

Note: The final report for this subteam for this semester was not available and the final presentation is linked instead.

Sensor Development - Spring 2017

Cheer Tsang, Luna Oiwa, Jingfei Wang

Abstract:

This semester, the Sensor Development subteam modified and recalibrated the fluidized bed solids concentration sensor. This sensor enable the High Rate Sedimentation (HRS) team to determine the concentration of suspended clay particles in a running flocculation recirculator. In addition, the team fabricated a submersible sensor to determine the depth and concentration of the sludge layer in a sedimentation tank. This sensor functions in the same way as the fluidized bed solids concentration sensor, with the added characteristic that the photometer is fixed to the end of a PVC tube.

Sensor Development - Fall 2017

Grace Zhang, Lois Lee, Srilekha Vangavolu

Abstract:

The Fall 2017 Sensor Development team worked on redesigning and calibrating the fluidized bed solids detector to be used for testing concentration of suspended particles in floc blankets as well as the submersible sensor designed to measure the height of the sludge blanket in the sedimentation tank.

Please note, no research report could be located for this team and the final presentation is linked instead