Foam Filtration, Fall 2011

Bradshaw Irish, Anna Lee, Rachel Philipson

December 12, 2011

Abstract

The Foam Filtration team is attempting to determine an application that utilizes polyurethane foam as a water filtration medium. Our work consists of running experimental trials which characterize the filtration properties of polyurethane foam. Polyurethane foam is not a conventional filtration medium, and through extensive work, we have proven that it can successfully produce effluent turbidities below US EPA standards. In addition to the characterization of foam as a filter medium, we have previously investigated the possibility of utilizing polyurethane foam at the point-of-use scale. A feasibility study determined that a polyurethane foam point-of-use unit would require the addition of coagulant and expensive moving parts. Therefore, the new focus of the Foam Filtration research team is on the design of an emergency water treatment system using polyurethane foam. This unit will consist of a roughing and finishing filter. Previous research characterized the performance of the finishing filter and current laboratory tests are focused on evaluating performance of the roughing filter.

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.

EStaRS, Fall 2014

Sarah Bolander, Skyler Erickson, Subhani Katugampala, Mary Millard, Savannah Wing

Abstract

The ultimate goal of the EStaRS (Enclosed Stacked Rapid Sand) Filter team was to develop an appropriate configuration for the stacked rapid sand filter system that could be implemented to treat groundwater in India. The stacked rapid sand filter is an excellent choice for treating water near the city of Ranchi, India, as the primary water source there is groundwater. The low turbidity of groundwater means that the full AguaClara treatment process is not required and filtration with dosing will suffice. After testing the current apparatus, the goal was to improve the design so that modular EStaRS filters can be run in parallel efficiently and sand bed fluidization can be detected. This team set up a system to allow for extended backwash times, proposed a weir design to run multiple EStaRS Filters in parallel, and set up a manometer system to analyze bed fluidization during backwash.

Fabrication - Fall 2014

Carl Talsma, Sara Sanz, Adrian Cobo

Abstract:

Make a hydraulic working scale model of the SRSF weir system for two filters to demonstrate how the weir system is used to set the flow to the filter during backwash. The hydraulics of this system are sufficiently complicated that explaining how it works is difficult and thus we need a working model for demonstration.

No final report was available for this team for this semester. The final presentation is linked below.

Enclosed Stacked Rapid Sand Filter - Spring 2014

Dhaval Mehta, Ariel Seidner, Sarah Sinclair, Lishan Zhu

Abstract:

The Low Flow Stacked Rapid Sand Filter (LFSRSF) is a scaled-down version of the AguaClara Stacked Rapid Sand Filter (SRSF). Similar in theory of operation to the SRSF, the LFSRSF is optimized to treat smaller flow rates of 0.8 L/s. The current LFSRSF design in India uses multiple valves to switch from filtration to backwash; the LFSRSF research subteam at Cornell seeks to reduce the number of valves by designing a filter that uses hydraulic controls. In detailing the teams work this semester, this report seeks to accomplish three main goals: to document the design process for such a filter, to document the fabrication process to facilitate easy technology-transfer to India, and to document filter performance as tested to date.

This semester, the team calculated appropriate design specifications for slotted manifold, trunks, plumbing systems and sand for the filter, as well as created a unique flexible-tubing derived sand drain. The team completed all fabrication, and also set up a water-recycle and leak containment system to support testing, as well as a pressure sensor array to test ow-distribution between sand layers. The team then solved multiple water- and air-leak issues. Ultimately, the team was successful in ensuring that the LFSRSF backwashes easily, efficiently and whenever an operator may so desire.

Teams working on the project further must tackle three major issues: the current filter cannot handle backwash flow rates greater than around 0.6 L/s, its entrance and exit tanks need to be raised, and the filter also faces significant challenges of larger-than-expected head loss during backwash. Once these issues are solved, the hydraulically-controlled LFSRSF shall be truly ready to be deployed in the field

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 - Fall 2017

Lucinda Li, Liz Cantlebary, Lingzi Xia, Dylan Vu

Abstract:

Sand filters have historically been used to lower the turbidity of water, and continue to be used in many conventional water filtration systems. Dynamic modeling, as opposed to static modeling, of rapid stand filtration accounts for the buildup of particles over time in the filter, and this un- derstanding is needed for better filter design and operation. Past sub-teams found that head loss increases linearly with time. This research proposes the hypothesis that flocs are captured in rings created by filter grains, which on a larger scale implies 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 will examine major and minor head loss, along with efflu- ent turbidity, to find optimal filter performance based on varying flow rate, coagulant dosage, and influent turbidity in a 1.967m L/s sand filter. Based on this research, it is hypothesized that the sand bed can filter a certain amount of mass before failing.

Foam Filtration Pore Size - Spring 2015

Lotta Van Leeuwen, Tianchen Yu, Caroline Caglioni

Abstract:

Abstract unavailable for this team for this semester.

Please note, the final report is not available for this team for this semester and the Final Presentation is linked instead.

Foam Filtration - Spring 2015

Marlana Hinkley, Alena Hutchinson, Ethan Keller, Alicia Peters

Abstract:

The primary goal of foam filtration is to design a low cost, locally sourced, easy to operate water filtration system. Throughout the semester, backwash cleaning efficiency experiments were performed on the small-scale filter, designed in Fall 2014 to hydraulically model the full scale filter implemented in El Carpintero. The objective of these experiments was to determine an empirical relationship between backwash pore velocity and the percent mass removal of the particles from the foam during the cleaning cycle. Experimentation with different pore sizes revealed a new mechanism for filtration: the foam acts as a sedimentation tank, providing a large surface area for the flocs to settle. This is contrary to the initial hypothesis that coagulant-covered flocs stuck to the inside of the pore walls, and that a large shear force would be required to remove the flocs during backwash. Evidently, there is still much to be understood with regards to the mechanisms behind filtration and backwash. 

Apart from work in the laboratory, the team continues to analyze data collected from experiments performed on the full-scale filter in El Carpintero by AguaClara engineer, Walker Grimshaw, to understand the discrepancies between performance in the laboratory and in the field. 

Much of the semester was spent preparing for the EPA P3 Conference held on April 10th and 11th in Washington, DC. The team fabricated a small scale model of the technology, prepared a technical report, and created a poster display for the competition, and received an Honorable Mention for its efforts in creating an “Off-Grid Solution to Drinking Water Treatment.”

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.

Enclosed Stacked Rapid Sand Filtration (EStaRS) - Spring 2017

Anna Doyle, Juan Guzman, Lilly Mendoza, Felix Yang

Abstract:

The Low Flow Stacked Rapid Sand Filter (LFSRSF) team was originally tasked with building a small, stan-alone sand filter to be implemented in communities in India. This semester the Enclosed Stacked Rapid Sand Filtration (EStaRS) team fabricated a new filter based on the design the Fall 2016 team created. The new design modifies the original LFSRSF; the filter column itself is shorter, the manifolds are sized differently, and the entrance and exit plumbing is now rigid PVC instead of flexible PVC. Next semester, the new EStaRS filter will be connected to the 1 L/s plant that has been built in the lab.

Fabrication: Open Stacked Rapid Sand Filtration (OStaRS) - Spring 2016

Mengqi Jiang, Subhani Katugampala

Abstract:

The construction of Open Stacked Rapid Sand Filters, or OStaRS, has been determined to be a difficult and labor-intensive process. the absence of a uniform installation procedure and proper construction methods leads to the overall inefficiency of the OStaRS assembly process. The Spring 2016 OStaRS Fabrication Sub-Team was tasked with developing three design modifications to ease with installation, which include a spacer system to be installed between filter modules, a movable platform for operators to stand on during assembly, and a holder system to fixate the dead end of the filter trunk line. The team has designed and fabricated the spacer and the platform systems. These designed were successfully stress tested, approved for field implementation, and are currently set for installation in one AguaClara treatment plant.

Enclosed Stacked Rapid Sand Filtration (EStaRS) - Spring 2016

Natalie Mottl, Michelle Bowen, Lilly Mendoza, Erica Marroquin

Abstract:

Manometer research & head loss modeling for greater efficiency and ease of use in Honduras and India.

No research report was available for this team for this semester. The final presentation is linked instead

Enclosed Stacked Rapid Sand Filtration (EStaRS) - Fall 2016

Susan McGrattan, Victoria Zhang, Elizabeth Johnson, Mikel Aurteneche

Abstract:

The EStaRS team’s goals for this semester were to design a new EStaRS filter that was compatible with the recently built 1 L/s plant. The 1 L/s plant’s sedimentation exit elevation provided a height constraint of 6 feet and required a scaled-down version of the existing EStaRS filter. The team first worked to gain a complete understanding of the EStaRS filter design and operation using experiences and observations recorded by previous teams. MathCAS calculations from the AguaClara design server were adjusted for the new design and AutoCAD drawings were created to provide a completed design that was ready for fabrication.

Water Quality Monitoring for Diarrheal Pathogens - Fall 2017

Ji Young Kim, Steven Lopez, Fletcher Passow

Abstract:

AguaClara plants effectively remove turbidity and fecal indicator bacteria (FIB) from drinking water sources in Honduras. However, no study has documented the plants’ ability to remove specific diarrheal pathogen species. This study identified best practices for collecting and shipping pathogen DNA from sampling locations in Honduras back to Cornell University. A literature review identified options for filtration systems, chemical DNA preservation solutions, and shipping protocols. Tests of the clogging behavior of 5um and 0.1um pore size membrane filters demonstrated that this filtration method’s 60 h projected run time for a 10L samples outweighs its gains in simplicity.