Acid Neutralizing Capacity, Fall 2010

Drew Hart, Roy Guarecuco, Larry Lin

Abstract:

In light of recent successful tests run by the AguaClara Engineers in Honduras with poly-aluminum chloride (PAC), an alternative coagulant to alum which consumes a fraction of the alkalinity, the ANC Control team is preparing to stop research with lime feeders because they will be largely unnecessary when PAC is adopted for all AguaClara designs. In order to bring closure to ANC research the team will write a final paper detailing the insights pertinent to lime feeder technology that AguaClara has gained over five semesters of research. We will also organize the ANC Control wiki page

Laminar Tube Flocculator, Fall 2010

Tami Chung, Alexander O’Connell, Karen Swetland

Abstract

The Fall 2010 Tube Floc Team of aimed to better understand the development of rapid flocculation through a series of experiments and data analysis. In previous semesters, we had focused on the variation of flocculator length and alum dose. With the completion of these studies, we encountered more questions regarding the fundamental mechanisms involved in the process. As a result we chose to focus on characterizing the minimum coagulant dose needed to initiate rapid flocculation for two difference coagulants, alum and PAC. We hope to use this data in the future to develop a theoretical framework describing the onset of rapid flocculation. In order to accomplish this goal and to ensure the accuracy of our data we made a number of improvements and modifications to the FReTA apparatus this semester. We are currently in the process of collecting data and hope to complete our planned experiments by the end of the Fall 2010 semester.

Acid Neutralizing Capacity, Fall 2010

Abstract

The ANC Control team has conducted laboratory research to investigate the feasibility of using a lime feeder to add alkalinity to the influent water of AguaClara plants. This was necessary in order to maintain the pH within the ideal range for flocculation after the addition the chemical coagulant, alum, which has an acidic effect. Low-alkalinity source waters in Honduras do not provide sufficient buffering capacity naturally to resist the drop in pH. The team has found that proposed lime feeder designs consistently fail to produce saturated effluent for a length of time which would make them economically and practically viable. The failure is believed to be caused by precipitation of calcium carbonate on the calcium hydroxide solid surfaces. The recent availability of poly-aluminum chloride, an alternative coagulant to alum with a much smaller acidic effect, in Honduras has reduced the need for lime feeders with AguaClara plants

Plate Settler Capture Velocity, Fall 2011

Ruonan Zhang, Xiaocan Sun, Yizhao Du

Abstract:

Through lab research we seek to understand the different influence of coagulant type, capture velocity, coagulant dose and raw water turbidity on the performance of the plate settler in AguaClara plants. We are using a tube settler to simulate those plate settlers in the full-scale plants. Through various changes in operating conditions, we expect to determine the best parameters, and this is of great significance in real practice. After that, we are going to pick out some of the best conditions and repeat the experiments with natural organics in order to see how humic acids affect overall performance.

Chemical Dose Controller, Spring 2011

Matthew Higgins, Adam Salwen, Christopher Guerrero

Abstract:

Accurate chemical dosing is important in water treatment plants to ensure optimal conditions for flocculation, sedimentation and disinfection of the treated water. The linear chemical dose controller uses laminar flow through a small diameter tube to create a linear relationship between head loss and chemical flow. The linear flow orifice meter then maintains a linear relationship between plant flow and water elevation. The linear relationships simplify chemical dosing for plant operators who may have a limited education. Our team is researching the upper-flow limit of the linear dose controller and developing innovative designs to increase the capacity of this system to function in plants with flow rates approaching and above 100 L/s. Furthermore, we are redesigning and simplifying the linear flow orifice meter algorithm to improve its precision and performance in the field.

Chemical Dose Controller, Summer 2011

Matthew Higgins

Abstract

Accurate chemical dosing in water treatment plants is imperative to ensure optimal efficiency during flocculation, sedimentation, filtration and disinfection. AguaClara designed the linear chemical dose controller (LCDC) and linear flow controller (LFC) systems to allow plant operators to reliably set and maintain a desired dose of coagulant and disinfectant. A linear relationship between head loss and chemical ow is created by using the major head loss through a small diameter tube to control the flow. To maintain this linear relationship, the systems have been designed to eliminate sources of minor head loss. Our team is actively working to minimize minor head losses through the systems, reduce the systems' maximum percent error and standardize the components and calibration techniques to be used to fabricate the systems in the field.

Chemical Dose Controller, Fall 2011

Jordanna Kendrot and Frank Owusu-Adarkwa

Abstract:

Continuous and accurate chemical dosing in water treatment plants is required for optimal efficiency during flocculation, sedimentation, filtration and disinfection. AguaClara designed the linear chemical dose controller (LCDC) and the Linear Flow Controller (LFC) systems to allow plant operators in Honduras to easily set and maintain the dose of coagulant and disinfectant through one system. A linear relationship between the head lost and chemical flow is created by using only major head loss, where the flow is controller by a small diameter tube. To continue using this linear relationship, the current experimental system has been designed with the goal of eliminating minor head loss. Our team is actively working towards the continuation of this work, decreasing the minor head losses throughout the systems, reducing the systems maximum percent error under 10% and standardizing the components and calibration techniques that will be used to fabricate this system in the field.

Stock Tank Mixing, Spring 2012

Julie Silva

Abstract:

The Stock Tank Mixing team is required to improve the mixing process for the coagulant and disinfectant in the stock tank. Previous teams have developed the centrifugal pump design, which can mix the following chemicals: aluminum sulfate (alum), polyaluminum chloride (PACl) and calcium hypochlorite (Ca(ClO)3). This team decided to focus on the use of polyaluminum chloride. Due to its chemical properties, it is most likely the future coagulant of most AguaClara plants. The stock tank mixing team plans to design a mixing system that will improve operator ease in use of the mixer, achieve a truly homogeneous mixer, and be scalable to larger plants. The team will also create operator guidelines, and provide the operator with a verification of homogeneity.

Coagulant Management, Spring 2013

Madeline Haas, Rudra Koul, Jack Newman

Abstract

Coagulants are an essential part of a water filtration plant as well as a signifiant operating cost. Therefore, it is very important that they be used as effiently as possible. This semester, the Coagulant Management team has calculated and analyzed the relationship between PACl density and concentration that was ultimately used in calculations necessary for centrifugal pump parameters and for hydrometer recommendations. In addition, the team brainstormed fabrication ideas for the coagulant injection point. The centrifugal pump was partially fabricated, but because of the density vs. concentration relationship calculated, the pump, once fully fabricated, can be tested using PACl. In addition, the Coagulant Management team has recommended the testing and use of a plastic (polycarbonate) hydrometer from Krackeler Scientific Inc. with a specific gravity range between 1.000 and 1.220.

Two Stage Coagulant Addition - Fall 2017

Yuhao Du, Andrew Kang, Alaia Malaina

Abstract

Two Stage Coagulant Addition team was designing and fabricating an apparatus that was used to experiment the benefit of having two stage coagulant addition, in opposition to one, while maintaining an efficient effluent turbidity. "Two stage" stood for adding clean coagulant after all previously added coagulant was fully covered by humic acid, which was the experimental substitution of NOM in the water. The research was based on Yingda's thesis, who studied the effect of humic acid on the coagulant dosing model. Based on the bonding mechanism, it could be hypothesized that two stage coagulant addition would increase the removal efficiency of particles. This semester, our group focused on comparing 1 stage addition with 2 stage addition and carrying on the experiment with different influent turbidities, as well as trying to improve Yingda's coagulant dosage model. By having a fixed HA/Clay concentration, we designed a ProCoDa increment system that will allow ProCoDa to increase the dosage of coagulants for separate experiments, without having to manually ending the experiment.

Lab process set-up

Laminar Tube Flocculator - Spring 2015

Luyan Sun, Tanvi Naidu, Kevin Shao

Abstract:

Research on the Laminar Tube Flocculator in Spring 2015 aimed to validate the results obtained by Karen Swetland with the FReTA system and to further investigate factors that affect the overall turbidity removal. The past semester’s team worked to test the new residual turbidity monitoring system, SWaT, in comparison to the FReTA system and to verify that the new system can obtain similar results to those obtained with the old system. However, the actual coagulant tubing size used in the previous SWaT experiment was different from that in the pump control method file. Because of the incorrect input in tubing size, the PACl dosages were not accurate. The Spring 2015 research derived correction factors that would make the previous date usable. Then experiments were conducted in the SWaT system to finish verifying Karen Swetland’s results. Future works includes experiments to determine if there is an optimal floc size which is small enough to combine with small clay particles yet large enough to be separated in the sedimentation tank. Also, future teams should study how dissolved organic matter (DOM) affects the performance of the flocculator and sedimentation tank. These findings will improve the performance of the flocculator and make it more effective for use in water supply.

Chemical Dose Controller - Fall 2016

Cynthia Chan, Anna Doyle, Ashish Sangai

Abstract:

The Linear Chemical Dose Controller (CDC) system was designed to maintain a constant chemical dose to the treatment train as the plant flow rate and influent turbidity change. Past CDC teams worked on improving the the design of the Constant Head Tank (CHT), and making the CDC system modular. This semester the CDC team redesigned the CHTs so that all four tanks were connected to each other, and so that the calibration columns were attached to the CHT module. Additionally, the team recreated and modified the modulat CDC system designed in past semesters to address the goals of being fully chemical resistant, compact, and simple in operation and maintenance. The new CHT will be demonstrated and eventually implemented in Honduras.

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.

Chemical Dose Controller - Spring 2017

Annie Cashon, Cynthia Chan, Susan McGrattan, Karan Newatia

Abstract:

The Chemical Dose Controller (CDC) system was designed to maintain a constant chemical dose to the treatment train as the plant flow rate and influent turbidity change. This semester, the CDC team worked on expanding the modular design from previous semesters in order to improve ease-of-use during operation, better access to the system for plant operators, and greater system efficiency overall. The team designed and fabricated a new and improved constant head tank and calibration columns systems. This semester the CDC team also collaborated with the 1 L/s plant sub-team to create a CDC system for low flow rates.