Water Treatment Technology Selection Guide – Spring 2014

Subhani Katugampala, Neelesh Bagga

Abstract:

This is the final research report of the Water Treatment Technology Selection Guide Team for Spring 2014. Our goal this semester was to design a selection guide that provides a clear rubric for evaluating and comparing water treatment technologies. A major part of this involved developing the framework and decision-making methodology for such a decision-support system. Current technology selection guides tend to focus on providing information on treatment technologies based on contaminant removal requirements, while ignoring the realities of resource-constraints and skill-constraints of communities, and without considering sustainable engineering practices. An expert guidance tool is needed to empower water supply professionals to make better decisions and to learn the constraints determine which technologies are appropriate.

Plant Cost Calculator – Spring 2014

Andrew Bales, Chris Mills, Derrik Yee

Abstract:

AguaClara designs low-cost water treatment facilities and desired a tool to estimate and present the capital and operational costs of an AguaClara plant. The goal of the Plant Cost Calculator team is to create such a tool to provide an accurate estimate of the costs associated with construct- ing and operating an AguaClara water treatment plant. The objective of the calculator is to allow users to easily obtain accurate design and operational cost estimates that can be compared to alternative water treatment options, and to make users better aware of the factors that contribute to the final plant cost. At the end of our first semester, the plant cost calculator team has completed the back-end for a working and easy-to-use calculator based in part on data from existing plants in Honduras. Future objectives will include developing a more attractive front-end interface, closer collaboration with WTTSG, and integrating India plant costs into the data used for prediction.

Ram Pump - Spring 2014

Ruben Ghijsen, Kelly Huang, Ruju Mehta

Abstract:

The team this semester focused mainly on rebuilding and improving the ram pump and its lab set-up. Major changes to the system from last semester include a more compact head loss system, higher overhead drive tank (to better simulate Honduras parameters), and an attempt to improve the air chamber design, In the end, the team was able to con- struct a working prototype that successfully pumped and delivered water through the entire head loss system. However, due to time constraints, the future team will have to make additional improvements to the system. They include a larger, encased recycling system, and more structural sup- ports to minimize instability. Although the initial run proved successful, additional testing could not be conducted due to computer malfunctions and again, time constraints. Had given the time, experimentation would be conducted regarding the 􏰃ow rate, head loss, reliability, and scaling. Future teams can now focus on these experiments since the prototype is basically complete.

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Wastewater Treatment, Spring 2014

Ge Gao, Maithili Gokarn, Walker Grimshaw, Ethan Keller, Caitlin McKinley, Amiel Middelmann, Luke Zhu

Arsenic Team, Spring 2014

Tanapong Jiarathanakul, Jason Koutoudis, Mingze Niu

Abstract

The modification of AguaClara sand filtration unit by coating the media surface with PACl was investigated in this research in order to remove arsenic from contaminated influent. This process is called adsorptive media filtration, which is one of the emerging technologies in water treatment processes. In order to ensure accurate arsenic analysis, the graphite furnace atomic absorption spectrometer (GFAAS) was aligned and calibrated extensively. Since the pre-programmed sampling procedure by the GFAAS had been proven ineffective in measuring low arsenic concentration, two specialized analytical methods called multiple injection method and large injection method were created to detect arsenic at low concentrations. These methods lowered the detection limit of arsenic concentration by the GFAAS down to 2 µg/L. In the experimental preparation, an upflow sand filter column was fabricated using a 1.20 m transparent PVC pipe with 0.622-inch inner diameter. The sand bed depth was 87 cm. Two peristaltic pumps were connected to stock solutions: coagulant (PACl) and groundwater with diluted arsenic concentration at 100 µg/L. In this experiment, both pre-treatment and co-treatment methods were employed. Using an approach velocity of 1 mm/s, the results showed the arsenic removal efficiency during the first 80 minutes of the experiment was at least 97%, which validated the removal efficacy of adsorptive media filtration technique.

Demonstration Plant, Spring 2014

Alice Reis, Erin Loughlin, Lauren Frazier

Abstract

The demo plant team is responsible for design, construction, and troubleshooting of the AguaClara Demo Plant. The successful operation of this plant is crucial in order to demonstrate the process of AguaClara plants to all stakeholders, including students, faculty, staff, community members, business partners, and potential sponsors. This spring semester, our research team focused on fixing issues with the current demo plant design, such as an unreliable flocculator and dose controller, unstable frame, and concerns with differences in hydraulic head. Our research includes conceptualizing and testing a more efficient and stable plant assembly and start-up for those unfamiliar with the technology; resolving issues with improper coagulant dosing and head loss differences; designing and implementing a new flocculator design; testing new fittings for the stacked rapid sand filter; and providing thorough documentation of the demo plan so that future teams would have less difficulty familiarizing themselves with the AguaClara demo plant. The redesigned demonstration plant is more stable with the addition of a middle bream and a contiguous bottom support. Overflow issues in the flocculator were addressed through the manufacture of a new flocculator, which contains an overflow weir and outlet. Inconsistencies with head loss were resolved by creating a Mathcad calculation file to determine the necessary lengths of a “long, straight” tubing from the constant head tanks. Increasing the capacity of the raw water stock tank from less than one liter to two liters allowed for an increase in continuous operation without interruption.

Laminar Tube Flocculator - Spring 2014

Victoria Chou and Yining Dai

Abstract:

Flocculators are an integral part of the water treatment process. The􏱕focculation process turns the colloidal matter within water into flocs that will eventually be removed through the sedimentation process. The creation and eventual settling of flocs formed in the flocculator results in cleaner, clearer water. According to Swetland et al.'s hypothesis, flocs that reach a certain size are no longer effective in removing colloids be- cause the shear on the surface of the flocs becomes too high for the colloids to attach. Thus, by breaking large flocs, they may regrow and scavenge additional small colloids that were not able to settle out from the suspension. The purpose of this series of experiments is to continue testing the Floc Breakup Theory and, if valid, to determine the most effective way to break up flocs in order to have the highest removal rate of colloidal particles. The settled water turbidity analyzer (SWaT), a new turbidity measurement system, was designed and implemented for the Spring 2014 research, in which the effluent water first travels through an angled tube settler with continuous 􏱕ow before being analyzed by the effluent turbidimeter. A base case test was run to serve as a control showing residual turbidity with the new turbidity measurement system. Adjustments to the new setup were made to accommodate for issues that arose from the new turbidity measurement system.

Foam Filtration - Spring 2014

Kristin Chu, Skyler Erickson, Melissa Shinbein, Jeffrey Suen, Kadambari Suri

Abstract:

The Spring 2014 foam filtration team will focus on improving the water treatment system designed in Fall 2013 and incorporating the knowledge learned on the trip to Honduras in January, 2014. This includes: redesign- ing the cleaning techniques to improve efficiency in removing dirty water off of the top of the foam, investigating foam re-expansion in a drum with vertical sides, designing the LFOM, and implementing a coagulant doser. The goal for this semester is to design, build, and test a compact system that can be easily transported and eventually implemented in small communities. In order to achieve this long-term goal, the Foam Filtration team will need to investigate multiple design options and create an operational system in the AguaClara lab. The foam filter will then be tested in Honduras.

Sed Tank Temperature Gradients, Spring 2014

Dhaval Mehta, Hui Zhi, Surya Kumar

Abstract

AguaClara is an engineering program based at Cornell University that develops sustainable  water treatment technology with current applications in developing countries. In Honduras,  one  of  the  countries  with  AguaClara  technologies,  the  treatment  plant  at  San  Nicolas  experiences raw water with a temperature gradient of around 1°C/hr during warming and  cooling  portions  of a  day. These gradients  are  primarily  caused  due  to  the  approximately  15km of piping that brings raw water to the plant, much of which is exposed to the sun.  Agua  Clara  plants  use  sedimentation  tanks  with  floc  blankets  and  plate  settlers.  The  temperature gradient  during warming  periods  causes a  circulation  current  to  form in  the  vertical Gflow sedimentation  tank, due  to  the effect of continually warmer water displacing  colder water. This current in the tank at San Nicolas causes flocs to aggregate on one side of  the  tank and rise up  to  the  top with  the hotter, less dense water; hence  the effluent water  leaving the tank is not sufficiently clean. Our experiment is motivated by this problem, with  the  goal  of  studying  the  problem’s  origins  and  providing  initial  research  towards  its  solution

Pipeline Cooling, Spring 2014

Alexandra Cheng, Apoorv Gupta

Abstract

The AguaClara water treatment plant in San Nicolas was inaugurated on April 5, 2014, and has successfully started operation. However, a major problem that has become apparent is the heating of raw water during the day from the source to the plant entrance tank. Raw water travels 4.5 km through a steel pipeline exposed to sunlight which has been identified as the likely cause for the temperature increase. Since the plant is hydraulic and gravity-powered, the temperature of the influent water affects its properties and behavior in the various stages of the AguaClara treatment system, particularly in the sedimentation tank. While the stacked rapid sand liter has been able to keep effluent turbidities low enough to be deemed acceptable, the resulting required amount of backwash places excess stress on the system; therefore, it is imperative to seek a method to maintain a relatively low raw water influent temperature to ensure plant success in producing potable water.

Floc Probe, Spring 2014

Alexandra Green, Tiago Viegas, Paul Vieselmeyer

Abstract

The visualization of the floc blanket in Aguaclara plants has been difficult and limited, so our team has tried to simulate it and create a new apparatus to solve or at least to reduce the problem. We found reports and materials from the turbidimeter team that could help in our task. Research was done on commercial sensors that could help monitor the floc blanket level, but none of the results were feasible. An experimental set up was also created in order to simulate the floc blanket and clear water interface with no success. Finally, a sludge judge apparatus was created to hopefully help with the observation of the floc blanket in San Nicolas.

Convection Flow in Plate Settlers, Spring 2014

Eric Grohn

Abstract

The AguaClara project team develops a simple, low-cost water purification plant for developing global communities. One part of the AguaClara plant is a sedimentation tank. During this stage of the purification, large coagulated contaminant particles (”flocs”) collect and settle out of the water, leaving it cleaner than before. Recently, one problem has been noticed with the current design of the AguaClara sedimentation tank. If the water entering the tank is warmer than the water already within, the tank doesn’t perform as well as it should. The suspected reason for this is that the warm buoyant water rises rapidly to the top of the tank, taking the flocs with it, at a velocity that is too great for the tank to function correctly. The top of the tank consists of an array of angled closely packed parallel plates called plate settlers. My project here is to determine the flow pattern for a convective flow through the plate settlers, with the hope that this will provide a clearer picture of the poor sedimentation tank performance. A 2d analytical solution is determined for the flow velocity between two angled parallel plates when the flow is convective. Further topics are discussed as they relate the sedimentation tank performance, such as turbulence between opposing flows and shear flow instabilities.

Village Source to Environment, Spring 2014

Diana Kelterborn, Sarah Levine, Nicholas Parisi, Rachel Whiteheart

Abstract

The newly formed Village Source to Environment Team combines the design of a distribution storage plan and wastewater treatment system for rural villages in India. Current distribution infrastructure consists of an elevated tank that fills and dispenses twice daily, each time supplying half the village’s water needs. This method is inefficient and inconvenient, since villagers can only obtain water when the tank dispenses and must carry it half a kilometer to their homes. This system also makes it impossible to ensure that each family receives their designated share of water. Furthermore, due to limited access to water, villages improvise unsanitary household storage. They obtain all water for washing, drinking and cooking from these open containers, meaning the entire source can be contaminated any time they use it. Our proposed distribution system will 2 pump water directly into villagers’ homes, replacing the elevated storage tank with smaller household tanks. Each tank will connect to a sink for sanitary use on demand. Additionally, the sink’s drain will allow us to eventually integrate a wastewater treatment or irrigation system. Small villages with limited resources often lack sanitary solutions for handling greywater and blackwater; we hope future teams will investigate strategies for treating wastewater for irrigation. Our work builds upon capstone design projects from the Fall 2013 CEE 4540 class that focused on a distribution system for the village of Gufu, India. We revised the distribution design and planned to add household storage tanks, however the distribution system design took the majority of our focus this semester. This new team was formed to facilitate AguaClara’s expansion to India. The local infrastructure, community sizes, and therefore required flow rates, differ significantly from those in Honduras. As a result, the team must take a very different approach to the problem. The Village Source to Environment Team has laid the foundation for distribution design this semester.

Turbulent Tube Flocculator, Spring 2014

Felice Chan, Jonathan Christensen, Stephen Jacobs, Ana Oliveira

Abstract

Since the Summer of 2013, the Turbulent Tube Flocculator team has been developing and optimizing a design for a lab scale turbulent tube occulator to better mimic the processes that occur at full scale plants. From this, a vertical occulator of approximately 1.5 m was constructed with 30 coils of exible tubings connected with pieces of metal pipe. Currently, the team is working on the rest of the experimental setup, which involves pumps, turbidimeters, pinch valves, clay stock, temperature and pressure sensors, Settled Water Turbidity analyzer (SWaT), rapid mix, and Process Controller software. Clay will be added directly to the head tank to keep the suspension stable in absence of coagulant. The coagulant, injected immediately following rapid mix, is responsible for aggregation of suspended particles present in the solution. Experiments will measure turbidity reduction as a function of coagulant dosage.

Stock Tank Mixing Team, Spring 2014

Alexandra Cheng and Apoorv Gupta

Abstract

The Stock Tank Mixing team has been charged with the task of designing and fabricating a tool to effectively and efficiently mix stock solutions of coagulant and chlorine. Currently, operators in AguaClara plants utilize a long PVC pipe to mix stock solutions to achieve chemical dissolution, but this method is inefficient and limits the ability of operators to mix large stock tanks. Uniformly mixed stock solutions are required for flocculation and disinfection; this fact is the driving force for creating a mixer to aid the formation of flocs in raw water and improve plant efficiency.

Fluidized Bed Flocculator -Spring 2014

Felice Chan, Jonathan Christensen, Stephen Jacobs, Ana Oliveira

Abstract:

Novel methods of water treatment, that do not use electricity and only require basic construction materials, are in demand worldwide in remote regions without established centralized water treatment. Gravity-driven unit processes must be developed for these water treatment facilities. Current hydraulic flocculators use baffles with dimensions on the order of meters to generate turbulence and achieve particle aggregation. An alternative approach is to use sand grains, rather than large solid sheets, as flocculator baffles. A fluidized sand bed flocculator occupies much less plan view area, but generates much more head loss. Implementation will depend on a balance of the cost of land and materials against the available hydraulic head.

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

Chemical Dose Controller - Spring 2014

Andrea Cashon, Saugat Ghimire, Jeanette Liu

Abstract:

The Chemical Dose Controller team completed the design and fabrication of the single lever arm assembly. This assembly will be utilized in low flow plants that only require a chlorine doser. The new Chemical Dose Controller maintains the same functionality of the previous model. It will also be chemically resistant and require fewer materials, lowering fabrication and shipping costs. The team also created a float valve for the constant head tank that has fewer corrosive metal components and has the floatin line with the orifice. The team has created a new height adjustment system for the constant head tank and a dosing tube air removal system that utilizes a wye channel. Additionally, the entrance tank float was redesigned to be smaller and lighter, for easier and cheaper shipping. Finally, the team created an items catalog that contains every single component - and it’s corresponding McMaster-Carr identification number - used in a Chemical Dose Controller system. This catalog will help future Chemical Dose Controller teams order components and construct new systems.

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