EStaRS, Fall 2012

Mihir Gupta, Kris LaPan, Rachel Proske

Abstract:

The use of filtration units for the treatment of drinking water is a common practice in engineering design. However these units are generally used for the treatment of large volumes of water. To improve upon this limitation, a stacked rapid sand filter was designed for low 􏰃ow rates. Work for the semester began with an existing filtration unit which did not contain sand, due to predicted failure from large head losses in filtration and backwash. The existing design was modeled in AutoCAD 2013 to provide an illustration of the system. Updates to this drawing were completed and will continue to be as fabrication phases occur. One of the primary tasks was to develop a mathematical model in MathCAD to calculate the flows and head losses throughout the system. The model was completed for filtration and backwash, and includes calculations for both cycles with and without sand present. Hydraulic testing was completed to determine the head losses in filtration and backwash, risk of sand transport through the backwash pipe, and 􏰃ow rates. These measurements and observations were compared with the mathematical model to determine its validity. According to head loss values obtained from the mathematical model, several changes were made to the filter prototype. Such fabrications included complete reconstruction of the backwash pipe, changing of valve types, and installation of NPT fittings and ball valves. Finally performance testing was completed to determine the effectiveness of the prototype in regards to decreasing effluent turbidity. Overall, it was determined that the filter prototype is highly effective at decreasing turbidity for several influent concentrations at the designed flow rate.

LFSRSF, Summer 2014

Richa Gwalani, Guneet Sandhu, Tom Schultz, Savannah Wing

Abstract

People in many parts of the world are still devoid of basic human necessity like clean drinking water. Many drinking water treatment systems in the global south face limited economic viability because of the unreliable source of electricity and expensive operation costs. Stacked Rapid Sand Filters (SRSF) were invented by the AguaClara team to eliminate the need for pumps or control equipment, thus making it more robust and reliable than conventional rapid sand filters. The low-flow stacked rapid sand filter (LFSRSF) is an adaptation of the SRSF for flow rates < 3.0 L/s and is currently being deployed in India for flow rates of 0.8 L/s serving communities of about 500 people. The previous LFSRSF research teams have been working on fabricating the laboratory version (version 1) of the filter with continuous improvements to the design aimed at simplifying the operation and maintenance of the filters. This version of the full-scale filter in the lab fabricated by the previous team has 0.2mm slotted pipes throughout and top and bottom manifolds consisting of single slotted pipes. The initial version 1filter is nearing completion in two villages in India, Rohne and Gufu. Our work was to fabricate the next version full-scale filter, version 2, which was built upon the previous teams version 1filter. In the 2nd version of the full-scale filter, we tried to mitigate problems faced by the previous version, such as overflowing of the inlet tank and the inability to backwash at designed ow rates. We also wanted to move towards the ability to handle and filter turbid water. This 2nd version of the full-scale LFSRSF will be used as a prototype for mass production by the Tata Water Mission in India. A major part of optimizing the operation of the filters included accounting for head loss incurred in the system and incorporating these changes in the final design of the critical components of the filter.

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.

EStaRS - Spring 2015

Sarah Bolander, Skyler Erickson, Liza Johnson, Subhani Katugampala, Lilly Mendoza

Abstract:

The Spring 2015 EStaRS team built upon the work of previous semesters to optimize the original filter design as well as to develop alternative strategies to sections of the filtering process. Over the course of the semester, the team altered the process for attaching the filter cap in order to prevent future cases of blow­off, adjusted the system for controlling water level height during backwash, and ran tests on filtration efficiency. While at the beginning of the spring semester the team’s goals also included developing a method of testing and recognizing bed fluidization within the filter, looking into a method of running multiple filters in parallel, and setting parameters for backwash duration and frequency, the team changed directions and concerned itself with the implementation of a new filter injection system to combat the problems associated with using slotted pipes.

EStaRS - Fall 2015

Skyler Erikson, Lilly Mendoza, Natalie Mottl, Lishan Zhu

Abstract:

The Fall 2015 EStaRS team reworked the lab scale setup of the EStaRS filter to work without a large pool to preserve lab space. The team then finished the orifice inlet implementation that was begun in Spring 2015, and provided an operating procedure for both filtration and backwash to avoid trapping sand in the inlets during the transition. The biggest takeaway from the operating procedure is that orifices can be operated successfully as long as the backwash transition does not create a drastic pressure change. Slowly closing the gate valve on the backwash siphon provides a gradual change and does not trap sand in the inlets. This procedure was the result of numerous inlet cloggings, and thus the team also devised a method for unclogging inlets without disassembling the filter. The team also implemented a pressure sensor to track headloss accumulation through the filter bed in the entrance tank. This pressure sensor was used to measure a clean bed headloss which is very close to the design clean bed headloss.

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

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.

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.