Stacked Rapid Sand Filer Pilot Scale, 2012 Spring

Eva Johnson, Jordanna Kendrot, Bill Kuzara

Abstract:

The stacked rapid sand filter has been proven to be an alternative to traditional rapid sand filtration systems, and their efficiency makes them an appropriate component in gravity powered municipal-scale water treatment facilities. In this study, a pilot-scale apparatus has been create as a model of the hydraulic controls throughout a full-scale stacked rapid sand filter system. After installation and field testing at Tamara, it is vital for the backwash segment of filter operation to be controlled for a more efficient use of the system. The purpose of the current experimentation and lab procedures are to determine the optimal backwash cycle time necessary for the filter to remove as much particulate matter as physically possible with a short filter-to-waste cycle, thus reducing the overall rinse cycle time. Further research will be needed in determining how to lessen bubble formation, be it in the inlet box or filter itself, and in measuring the change in flow distribution throughout filtration and backwash. A four-layer rapid sand filter was created to test filter efficiency versus monetary compensation from using less sand in the filter box, but was shown to have less than optimum particulate matter removal when compared to the tested six-layer.

Stacked Rapid Sand Filter Full Scale, Spring 2012

Michelle Wang, Steph Lohberg, Chris Holmes

Introduction:

The purpose of this report is to effectively summarize the progress that has been made to fabrication methods for the stacked rapid sand filtration system over the course of the semester. The stacked rapid sand filtration system is a new technology developed by AguaClara. It has many advantages over traditional sand filtration systems. First, it uses less water to backwash, because the filter layers are stacked. The filtration system also uses the same water for to backwash all the filter layers, producing a concentrated waste stream and reducing backwash time. Furthermore, this technology is much easier to operate than conventional rapid sand filters. It fits all the criteria of AguaClara technology, as the normal filtration and backwash cycles are driven by gravity. Materials are relatively cheap and widely available in Honduras. Finally, this filtration system has been proven to lower the effluent turbidity sufficiently, producing treated water below the EPA standard of 0.3 NTU and often even less than 0.01 NTU. The first field scale design of this filtration system was recently implemented at the AguaClara plant in Tamara. There have been several previously unforeseen issues that have arisen. In Tamara, in order to fit the slotted pipes into the trunk line and end lines, compression slots were cut into the slotted pipes. However, this allowed sand to leak into the inlet and outlet plumbing. Sand leakage is a serious issue because it increases head loss in the filter, reduces the length of the filter cycles, lowers the efficiency of the filter, and makes it harder to backwash. One of our main goals for this semester was to find a way to make a sand-tight connection between the slotted pipes and the trunk line and end lines. Another challenge we are facing is to find a new construction method so that the manifold can be built outside of the filter box. After the manifold is completely assembled, it will be lowered into the filter box as a unit. A key part to our progress this semester is the steady feedback from the team in Honduras at the Tamara site. Changes that we make this semester will aid in the maintenance of the Tamara filter and the design and implementation of the next stacked rapid sand filtration system in San Nicolas.

Stacked Rapid Sand Filter Bench Scale, Spring 2012

Danhong Luo, Weiling Xu, Huifei Wu, Main Editor: Michael Adelman

Abstract:

Stacked rapid sand filltration (SRSF) is a novel technology for AguaClara water treatment plants. Our team goal is to improve the performance of the SRSF by studying fundamental questions such as the self-healing nature of ow distribution among layers and the effect of upstream energy dissipation rate on performance. In the self-healing test, we found that it is hard to let the sand bed itself control what the flow distribution will be, and that surface removal dominated in the filtration process. The depth filter test reveals that surface removal dominated in the self-healing test, and flow distribution improved when surface removal effects were eliminated. For the energy dissipation rate test, we assume the filter performance would be improved with the increasing energy dissipation rate, while current experiments have not show the result. Therefore, further testing should be addressed in the energy dissipation rate study.

Low Flow Stacked Rapid Sand Filter , Summer 2012

Christian Compton, Alli Hill, Amanda Rodriguez, Samuel Taube

Abstract:

No abstract available for this research.

StaRS Filter Theory - Fall 2016

Theresa Chu, Jonathan Harris, Lucinda Li, William Pennock

Abstract

Dynamic models of stacked rapid sand filtration has proved elusive in accounting for the diminishing pore space and increasing head loss. Empirical data has shown that head loss increases linearly over time despite filter breakthrough. Dirty filter bed head loss shows that minor losses add to head loss over time. A new model for dynamic filtration is proposed, which models captured particles as embedded rings of flocs in the filter bed. Particle removal through filtration is described with an active filtration zone of empty pores filling up with particles. This zone moves throughout the layer of sand until there is no available pore space and surface area for particles to attach.

StaRS Filter Theory - Spring 2016

Theresa Chu, Lucinda Li, Jonathan Harris

Abstract

A mathematical model describing sand filtration would promote the understanding of stacked rapid sand filter performance. Variables affecting filter performance include coagulant dosage, influent turbidity, and sand filtration depth. The collected data from a model filter informed a mathematical model explaining the effect of coagulant mass on the filter’s effluent turbidity, head loss, and failure time. Experiment runs demonstrated that increasing coagulant dosage led to an increase in head loss and decrease in time until filter failure as well as vary effluent turbidity. Head loss curves for the various PACl dosages had the same trend after filter failure and converged to the same value after a 24 hour run time.

StaRS Filter Theory - Spring 2018

Alison Valibuena, Liz Cantlebary, Dylan Vu

ABSTRACT:

Sand filters have historically been used to lower the turbidity of water and are still used in conventional filtration systems. The research in this report is based on the hypothesis that flocs are captured in rings created by filter grains, which implies there is an active filtration zone where empty pores become clogged by the flocs. This active zone moves throughout the bed until there is no remaining space for particles to clog. This research examines the factors that influence the time it takes for the filter to clog. Several key factors affect the failure time including size and density of flocs and were explored through experiments with different coagulant doses and with a constriction placed before the filter.

StaRS Filter Theory - Fall 2019

Wenjie Lu, Claire Kenwood, Kelly Ly

ABSTRACT:

StaRS (Stacked Rapid Sand) Filtration is crucial to the water treatment process. As one of the last steps in AguaClara’s water treatment, StaRS filters are responsible for removing the last of the unwanted particles. In order to operate effectively under EPA standards, the filters must reduce the turbidity to 0.3 NTU or less. In efforts to better refine the AguaClara filters, variables such as grain size, the height of the active zone, coagulant dosage will be tested in order to increase the failure time. At the beginning of experimentation, the Fall 2019 StaRS sub-team will focus specifically on the grain size.

StaRS Filter Theory - Spring 2019

Barbara Oramah, Lainey Reed, Pablo Alonso Alguacil and Ronya Strom

ABSTRACT:

Stacked Rapid Sand (StaRS) Filtration is the last stage in an AguaClara treatment plant. The filters are used to further reduce the turbidity of water to meet EPA standards of 0.3 NTU or less. As a whole, the StaRS sub-team is working to develop a mathematical model to describe sand filtration. This semester, the StaRS Filter Theory team worked towards running experiments with the three newly constructed StaRS filters with varying sand grain sizes. This research will show the extent to which sand grain size has an effect on filter performance.

StaRS Filter Theory - Fall 2015

Isha Chaknalwar, Theresa Chu, Michelle Lee

Abstract:

Modeling the physics of particle capture in stacked rapid sand filters allows for greater understanding and further innovation in filtration. A two-layer sand filter will be built to measure filtration performance parameters of effluent turbidity, head loss, and time until turbidity breakthrough or excessively high head loss. Sand filtration should be effective in removing small flocs, so flocculated influent water with coagulant and clay will enter the filter to simulate filtration and clogging.

StaRS Filter Theory - Spring 2015

Theresa Chu, Nick Coyle, Alexandra Schwab

Abstract:

The Stacked Rapid Sand Filter Theory team designed and built an apparatus to induce clogging and test the head loss across a slotted pipe, which allows the water to flow directly into the filter without sand leaving the filter. Experiments were run with high turbidity and coagulant doses to clog the slotted pipe and determine which influent conditions led to clogging and high head loss. Slotted pipes as an injection system for the stacked rapid sand filters have proven to be problematic due to clogging. Results show that floc build up of coagulant clay increased head loss and clogged the slots.

StaRS Filter Theory - Fall 2018

Barbara Oramah, Lainey Reed, Emily Spiek

Abstract:

Stacked Rapid Sand Filtration is the last stage in an AguaClara treatment plant. The filters are used to further reduce the turbidity of water to meet EPA standards of 0.3 NTU or less. This semester, the Stacked Rapid Sand (StaRS) Filter Theory team constructed 3 StaRS filters with sand of varying sizes. These filters will be used in future experiments to analyze how specific parameters, including sand grain size and coagulant dosage, affect filter performance. The StaRS Filter Theory team has spent the semester compiling a manual so that future teams can run experiments and reconstruct experimental filters if necessary.

StaRS Filter Theory - Spring 2020

Wenjie Lu, Claire Kenwood, Kelly Ly, Valentina Dai

Abstract:

StaRS (Stacked Rapid Sand) Filtration is crucial to the water treatment process. As one of the last steps in AguaClara’s water treatment, StaRS filters are responsible for removing the last of the unwanted particles. In order to operate effectively under EPA standards, the filters must reduce the turbidity to 0.3 NTU or less. In efforts to better refine the AguaClara filters, variables such as grain size, the height of the active zone, coagulant dosage will be tested in order to increase the failure time. At the beginning of experimentation, the Fall 2019 StaRS sub-team will focus specifically on the grain size.