High Rate Sedimentation - Plate Settlers, Spring 2016

Albert Cheng, Sidney Lok, Yuqi Yu, Lishan Zhu

Abstract

This semester, the goal of the High Rate sedimentation - Plate Settlers team was to maintain a suspended layer of colloidal particles (flocs) at upflow velocities higher than 1 mm/s. The suspended layer, referred to as the floc blanket, circulates flocs, enhances flocculation, and is self-cleaning. As the floc blanket grows in height, it spills over a weir into a sludge collection chamber to prevent sludge build-up inside the sedimentation tank. increasing the upflow velocity in the sedimentation tank decreases the necessary plan-view area and cost of construction. A high density floc blanket is necessary to prevent flocs from escaping the sedimentation tank at higher velocities. The High Rate Sedimentation - Plate Settlers team explored different plate settler geometries in the sedimentation tank to concentrate the floc blanket.

High Rate Sedimentation (Floc Blanket), Spring 2016

Ogechukwu (Oge) Anyene, Isha Chaknalwar, Josiah Hinterberger, Ziwei (Vanessa) Qi

Abstract

The High Rate Sedimentation - Floc Blanket team built a sedimentation tank model with the goal of increasing the upflow velocity and decreasing the plan view area, without degrading the performance of the floc blanket inside the tank reactor. Under high turbidity conditions, a stable floc blanket was maintained under upflow velocities from 1-4 mm/s. Two method of encouraging floc re-circulation, viz., in-reactor lamella plates and sludge recycling, were tested to observe effects on effluent turbidity. Results indicated that neither method had a strong enough effect to fully recommend increased upflow velocity, but future testing in improved apparatus with low turbidity influent has potential.

Milli-Sedimentation Fall 2016

Jillian Whiting, Tianyi Wang, Janak Shah

Abstract

The goal of the milli-sedimentation team was to find and explore the boundaries between sedimentation and filtration which could be used to reduce the size and residence time of AguaClara plants. The technology was designed using coffee straws that are sized between the spacing of plate settlers (10 mm) and the porosity of filter material (0.1 mm). The size of the plant would be on the scale of a small town or village, less than 1000 residents, replacing what the foam filter did in El Carpintero. One of the biggest challenges for the semester after building the sedimentation-filtration system was attempting to clean the apparatus, as this determined the feasibility of the design.

Microbiological Water Safety Monitoring, Spring 2016

Jacqueline Dokko, Janak Shah

Abstract

The ultimate goal for the microbiological water safety monitoring (MWSM) team is the development of a test that detects pathogens in water. The test must be of low cost (under ten dollars for each test), have a reduced incubation time from the standard 48 hours, and be able to be used in a low-resource setting such as Honduras. The team tested methods indicating the presence or absence of bacteria compared to quantitatively determining bacterial presence. Upon understanding the cost and efficiency of each method, it was possible to narrow down the methods that could be used as a model for microbial detection for AguaClara purposes.

Prefab 1 L/s - Spring 2016

Kimberly Buhl, Claire DeVoe, Meryl Kruskopf, and Felix Yang

Abstract:

The goal of the Prefabrication 1 L/s team was to research, test, and provide fabrication methods to be used when constructing the 1 L/s plant design in Honduras. The team worked on an approximate 1/10th flow rate scale model to design novel geometries for a low-flow flocculator and sedimentation tank while implementing known AguaClara fluid mechanic techniques. The cost per capita associated with these plants was calcu- lated to be much lower than plants built using traditional construction methods. Recommendations on design and fabrication methods were re- layed to future teams working on full-scale plant production.

Fluoride - Spring 2016

August Longo, Pooja Desai, Katie Dao

Abstract:

In many developing countries, high levels of fluoride in groundwater have been found to have chronic effects on bone health. Though some countries intentionally add fluoride to water in order to strengthen teeth, overexposure to fluoride has grown as a problem worldwide. The Fluoride team has been working to solve this very issue, by testing and developing a fluoride removal system fit for AguaClara plants in India and Honduras. In spring 2016, the Fluoride team built on the previous work of the Fluoride and Countercurrent Stacked Floc Blanket Reactor team to create a more optimal and efficient fluoride removal system. In the fall, the Fluoride team worked to understand the efficiency of fluoride removal using polyaluminum chloride (PACl) while the CSFBR team developed a reactor system to remove undesirable soluble particles. This semester, a new system was built consisting of a single floc blanket formed using PACl and clay. In the future, this system will be optimized by changing flow rates and dosages to better understand fluoride treatment and optimize AguaClara plants for fluoride removal.

CSFBR - Fall 2016

Jacqueline Dokko, Javier Espada Fraile

Abstract

The countercurrent stacked floc blanket reactor is a system for removing suspended solids or dissolved dyes by coagulating them into larger lumps of particles referred to as flocs using opposing currents to run clean water one way and floc-ridden water the other way. Using two standardized reactors, dye and coagulant concentrations, and flow rates, the team worked towards determining whether multiple reactors in a series is more efficient than a single, long reactor. With the known mechanism and the result of the previous research, this semester’s goal was to intensify dye removal by modifying the design of the reactor, system flow path and flow rates. For the future, the flocculator will be modified to be longer allowing larger flocs to form, increasing efficiency of the system as a whole since the discrepancy in flocculator size prevented comparable performance between the single reactor system and the system of reactors in series.

CSFBR - 2016 Spring

Surya Kumar, Christine Leu, Amlan Sinha, Cindy Dou

Abstract

Floc blankets, which are suspended layers of highly concentrated flocs, have the potential of being a more efficient option for removing arsenic, fluoride, and certain dyes in terms of energy and water consumption than currently employed techniques. For floc formation, a coagulant needs to be added to the water, allowing particles to adsorb to each other when they collide. Previous research has shown that the coagulant, polyaluminum chloride (PACl), has properties that allow arsenic, fluoride, and certain dyes to adsorb to its surface. The first iteration of this research used three floc blankets in series with a counter-current flow of contaminated water and flocs. By feeding flocs from the last reactor into the second, and from the second into the first, the PACl’s surface area can be saturated. To test this theory and apparatus, a dye, Remazol Brilliant Blue R (RBBR), was chosen to be the contaminant due to its less toxic nature and visual component. With this apparatus and contaminant, this semester’s goals were to test dye removal efficiency from water with varying concentrations of clay, PACl, and dye. With a 1:1 ratio of PACl to dye, a dye removal efficiency of roughly 80% was achieved. However, the transportation of flocs from the third reactor to the second and first was not sustanaibly achieved.

High Rate Sedimentation - Summer 2017

Christopher Galantino and Andrew Kang

Abstract:

The High Rate Sedimentation team designed, fabricated, and experimented on various sedimentation designs with an upflow velocity of 3 mm/s while maintaining a efficient effluent turbidity and reducing cost and space. Working off where the Spring 2017 team left off, the HRS team continued to research the effects of floc blanket height, tube settler length, varying geometries, and the size-driven floc blanket formation hypothesis. The HRS team concluded that the height of floc blanket may not provide better performance, as originally thought. Also, it has been concluded that the Trapezoidal geometry is not necessary, but provided insight on the behavior of floc on bends.

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.

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

Filter Constrictions - Spring 2017

Jillian Whiting, Janak Shah, and Samantha He

Abstract:

The goal of the Filter Constrictions Team was to test the hypothesis that particles are captured preferentially at flow restrictions in sand filters. There was evidence for this from work done by the Milli-Sedimentation Team and the Stacked Rapid Sand (StaRS) Filter Theory Team. The goal of the team was to create a flow constriction in a 0.5 mm channel in a flow cell reactor, and take a video of the particles at the constriction. The video was taken using Point Grey FlyCapture Software, and provided evidence about the hypothesis that flow constrictions serve as particle collection sites.

Anaerobic Fluidized Bed Reactor - Spring 2017

Clare O’Connor, Evan Greenberg, Peter Martin

Abstract:

The initial focus of the Spring 2017 Anaerobic Fluidized Bed team (AFB) was to continue developing declogging mechanisms for the reactors, however it was learned that side-stepping declogging was possible by focusing on steady-state operation of the reactors. Thus, the middle of the semester included design of two reactor set-ups designed to determine the fastest hydraulic residence time (HRT) that could feasibly be used. The new designed showed that not enough was known about the treatment process to move forward productively, so an extensive literature search was performed to gather more information necessary for a possible redesign in the fall.

Fluoride - Fall 2016

Michelle Cheng, August Longo, Briana Vidal

Abstract

The Fluoride subteam seeks to develop and sustainable, inexpensive fluoride removal system for implementation in upcoming AguaClara plants located in India. After earning an EPA Phase II grant for last semester’s fluoride removal reactor, the current subteam hopes to develop a better method of fluoride purification by partnering with the CSFBR subteam and researching the effectiveness of reactors in series versus a single reactor system. At the beginning of the semester, the subteam identified potential issues with floc buildup at the bottom of the apparatus. Thus, a smoothly sloping bottom insert was incorporated into the single system reactor for all comparison experiments. The subteam then analyzed the effectiveness of fluoride removal in a significantly shorter reactor. It was determined that although a shorter reactor would reduce fabrication cost, the lack of sufficient space for floc blanket formation yielded impotable water. After performing a series of side-by-side experiments, some data has been collected to compare functionality between the single reactor system and the CSFBR subteam’s reactor in series, the results are not yet conclusive. In future semesters, more comparable data needs to be collected to draw concrete final conclusion as to which system is more effective.

Ram Pump - Fall 2016

Javier Paternain Martinez, Christopher Galantino, Luna Oiwa

Abstract

The purpose of the Ram Pump team is to design and develop a properly functioning hydraulic ram pump, or hydram, for implementation in AguaClara plants. The hydram can be used to deliver water from below the facility back to the top for utilization in chemical stock tanks or to collect water at higher elevations for alternative uses. The team’s goal for this semester is to find a practical method for measuring the pump’s flow rate and efficiency, to determine the effects of adding distribution piping to the bottom of the apparatus, and implement method to solve issues as they arise.

Ram Pump - Spring 2016

Priya Aggarwal, Juan Guzman

Abstract

The Ramp Pump team was created to design, construct, test, and ultimately implement a hydraulic ram pump for AguaClara plants. The Ram Pump is located at the lowest level of the plant and is used to pump water either to a storage tank or directly to chemical stock tanks located at the top level of the plant. The team’s goal for the semester was to finalize designs for a self-contained pump, which is intended to maximize space efficiency. The team confirmed the viability of an enclosed vertical ram pump design over the course of several iterations. The team also redesigned the spring manipulation system and has a design that is ready to be implemented in AguaClara plants.

Humic Acid, Kaolin, Floc/Sed Model - Fall 2017

Ziwei (Vanessa Qi), Ye Rin (Erin) Kim, Wen Tien Dai

Abstract:

The Fall 2017 Humic Acid team was motivated to study the impact of the humic acid particles in water. Throughout the Fall 2017 semester, the team plans to explore the existence of optimal coagulant dosage that gives the lowest effluent turbidity at various humic acid concentrations. Then, the team seeks to set up a mathematical model that calculates the optimal coagulant dosage vs. humic acid concentration. A series of controlled experiments will be conducted with a computer software.

Lab Set-up

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.

UASB - Spring 2018

Zac Chen, Jennifer Jackson, Ian Cullings, and Ananya Gangadhar

Abstract:

Since Spring 2017, the AguaClara Upflow Anaerobic Sludge Blanket (UASB) Team has been working on a detailed design of modified, pilot-scale UASB reactor originally proposed in an EPA P3 proposal. A UASB reactor treats wastewater anaerobically and produces biogas as a by-product. Working towards that goal, the team has created Python code to record the design process and calculations for this AguaClara UASB. This document serves as a master guide for the design process.