A. Summary of Phase I Results

1. Background and Problem Definition

The Cornell AguaClara project team designs sustainable drinking water treatment

technologies. AguaClara’s commitment to sustainability encompasses environmental, social and

economic feasibility. Fluoride removal is challenging especially in rural areas and on the village

scale because treatment methods are limited. In Phase I we conducted preliminary research to

evaluate the feasibility of improving the Nalgonda method of fluoride removal. This work builds

on a previous EPA P3 project where we demonstrated efficient removal of arsenic with

polyaluminum chloride (PACl).

According to the World Bank, India is the leading user of groundwater in the world, with an

estimated demand of 230 cubic kilometers per year (The World Bank, 2012). More than 80

percent of drinking water comes from groundwater sources (The World Bank, 2012). This

dependency on groundwater becomes a critical problem when faced with the presence of fluoride

contamination (Figure 1). Natural geological sources are the primary cause of the high fluoride

levels. The World Health

Organization (WHO)

guideline for fluoride in

drinking water is 1.5 mg/L

(WHO, 2011). However in

some places, such as areas

within the Ajmer district

of Rajasthan state, India,

fluoride contamination

can reach levels as high as

18 mg/L (Hua, 2008).

Fluoride contaminations

above 1.5 mg/L can cause

detrimental health effects

to users such as dental

fluorosis.

Fluoride is a difficult contaminant to remove because the ions are highly soluble in water.

Current methods (see Singh et al., 2014) are based on the principle of adsorption (Raichur an

Jyoti, 2001), ion-exchange (Singh, 1999), precipitation–coagulation (Saha, 1993 and Reardon

and Wang, 2000), membrane separation process (Amor et al., 2001), electrolytic defluoridation

(Mameri et al., 2001), and electrodialysis (Hichour, 1999). Of current available fluoride removal

strategies, one of the methods that has significant potential to be implemented in small

communities is the Nalgonda method. According to Singh et al., (2014), the problem with the

Nalgonda method is that it is too expensive. The Nalgonda method requires a high dose of

aluminum sulfate coagulant to aggregate with fluoride and precipitate. A study conducted by

Dahi et al. (1996) suggests that 13 g/L alum (1.2 g/L as Al) is needed for the Nalgonda method

to effectively treat fluoride levels between 9 and 13 mg/L. Despite the high concentrations of

added coagulant, the fluoride residual in the test was still unable to meet the WHO fluoride

guideline of 1.5 mg/L. The high dose of aluminum sulfate also leaves high sulfate residuals in

the water, which causes taste and odor issues (Fawell, 2006).

Figure 1. Global distribution of fluoride in groundwater (Amini

et al., 2008).

In Phase I of this project, the AguaClara project team replaced aluminum sulfate with

polyaluminum chloride (PACl) as the coagulant in hopes of better efficiency and the absence of

sulfate residuals. After rapid mixing, the solution was sent through a sand filter column to

remove the fluoride and PACl precipitates. Results showed that fluoride concentrations could be

reduced from 10 mg/L to 0.6 mg/L to meet the WHO standard at a PACl dose of 50 mg/L as Al.

These results suggest that the combination of PACl and a continuous flow reactor that includes

direct filtration provided a significant improvement in performance over the Nalgonda method.

The proposed Phase II research would augment these initial experiments by investigating

alternative floc blanket reactor configurations to increase run times beyond those obtained using

direct filtration.

People

The AguaClara program empowers communities and community members with sustainable

technologies and the knowledge to operate and maintain their water supply infrastructure. A

commitment to open source and transparency fosters a continuous effort to improve the

technologies based on feedback from communities including real-time web-based performance

monitoring (http://monitor.wash4all.org/). High value research focused on developing high

performing, low cost, planet-friendly technologies and an agile development philosophy requires

trust based engagement with communities to accelerate the product development cycle. This idea

is evident in the Research, Invent, Design, Engage (RIDE) philosophy that AguaClara employs

to bring clean drinking water to communities. Involving communities fosters a sense of pride and

ownership and encourages sharing of observations and new ideas that accelerate innovation.

AguaClara values not only the scientific basis for treatment system design, but also a

growing network that includes government ministries, water sector professionals, non-

governmental organizations (NGOs), bilateral donors, communities, and their water authorities.

In Honduras the Cornell AguaClara program partners with Agua Para el Pueblo (APP), an NGO

that works with underserved towns to implement the AguaClara design for a municipal water

treatment system that then provides safe water on tap. The resulting water treatment plants are

owned and operated by the community water authority which hires plant operators, procures

necessary chemicals, and collects a water tariff from each household to sustainably cover

operating and maintenance costs. APP provides ongoing technical support for the community

water authorities which is a key reason why AguaClara treatment plants sustainably produce safe

drinking water in communities that were previously underserved.

Networks similar to those currently established in Honduras are also being developed in

India. A comparable method of collaboration will be incorporated into designing and

implementing the fluoride treatment technology.

Prosperity

Removal of excess fluoride from groundwater has the potential to benefit many people with

better health. Fluoride in high amounts can damage bones, deteriorate teeth and lead to growth

issues in children (WHO, 2004). The proposed fluoride removal method can also be applied to

other contaminants including arsenic. The Nalgonda method of fluoride removal requires large

aluminum sulfate dosages to be effective. Given an aluminum sulfate dose of 13 g/L, an

aluminum sulfate cost of approximately $1/kg, 20 L/person per day (WHO, n.d.), and a 6

member household yields a cost of almost $50 per household per month. This cost is too high for

many households in rural villages even if the amount treated is reduced to 2 L/person per day.

Additionally, too much aluminum sulfate can cause high residual sulfate levels and potentially

health problems (Hua, 2008). The continuous flow, PACl-based method has the potential to

significantly reduce the cost for safe water in rural communities. The removal of excess fluoride

will reduce healthcare costs and improve economic productivity.

Planet

AguaClara designs water treatment technologies to be ultra-low energy (zero electricity) and

to minimize environmental impacts. This is evident in technologies such as the stacked rapid

sand filter tested in Phase I research as the final step of fluoride removal. Traditional filters use

electricity to power backwash pumps, while the AguaClara design relies on manipulation of a

siphon to switch between forward filtration and backwash and uses the same total flow for both

filtration and backwash modes of operation (Adelman et al., 2013).

The continuous flow PACl method of fluoride (and arsenic) removal that we are developing

uses less coagulant and thus simultaneously reduces cost and the impact on the environment for

resource extraction and waste management. Our first goal is to maximize the efficiency of the

fluoride removal as measured by the mass of fluoride removed per mass of coagulant utilized to

reduce the amount of sludge produced and lower the operating costs. Options for safe final

disposal of the sludge include binding with Portland cement (Ahmad, 2013).

Implementation of the P3 Project as an Educational Tool

The AguaClara program began in the fall of 2005. AguaClara is an innovation system that

engages Cornell students to research, invent, and design electricity-free novel water treatment

technologies that are needed in both developing and developed countries. The program initially

included undergraduates and M.Eng. students and then added Ph.D. students in 2007. To date

more than 525 undergraduates, 100 Master of Engineering, and 4 Ph.D. students have

participated in the program for academic credit. Each semester about 50 undergraduate and 10

Masters students participate in the program. Undergraduate and Masters students come from

across the university with the majority from engineering and currently over 70% are female.

Students engage through a novel curriculum that has 3 different project courses (CEE

2550/4550/5051-2) that co-meet, making it possible for students from first year to M. Eng. to

join the project teams and do research that leads to improved water technologies. The project

courses are offered every semester. In addition to the project courses, the curriculum includes a

theory course, CEE 4540, that provides the basis of the AguaClara water treatment technologies

and serves as a repository for the growing body of knowledge generated by the program. The

final two courses, CEE 4560 and CEE 4561, are the preparation and reflection courses that

bookend the two-week engineering-in-context trip to Honduras. The students do not build the

water treatment plants. That is the purview of APP in collaboration with a community. The

engineering-in-context trips provide an opportunity for an exchange of ideas, with Cornell

students demonstrating new technologies to APP and, in turn, learning about water treatment

successes and failures from the Hondurans. Those successes and failures are lessons learned that

are taken back to Cornell to guide the next innovation cycle.

The AguaClara project courses are part of a revolution in engineering education. Instead of

having to wait until junior or senior year to engage with real engineering, students from first year

to Master of Engineering join forces and combine their skills to develop new and improved water

and wastewater treatment technologies. Students learn from each other and are highly motivated,

knowing that what they discover will be used to provide safe drinking water for communities in

Honduras and India.

The proposed research will be conducted by students in Cornell University’s AguaClara

program as part of our RIDE innovation system. Student teams collaborate with partner

organizations to Research, Invent, and Design improved water treatment technologies and then

to Engage with implementation partners to build the facilities and assist communities with their

maintenance and operation. The AguaClara project presently consists of 70 students working on

18 different project teams. The teams are researching all of the unit processes in surface water

treatment plant, 3 different wastewater treatment processes, refining the design code for surface

water treatment plants, developing draft design code for upflow anaerobic sludge blanket

digesters, inventing fabrication methods for a village-scale water treatment plant, in addition to

the research into fluoride removal that is the subject of this proposal,

Multidisciplinary Teamwork

Sustained collaboration between faculty and students fostered the productive research that

was obtained in Phase I of this research. Environmental and chemical engineering students

optimized reactor performance using reactive characteristics of chemicals. Civil engineers

provided suggestions for the materials and design process of the filter system. Additionally,

students that study Human Biology, Health, and Society offered insight on the implications of

high fluoride concentrations on human health. These dedicated researchers form the foundational

relationships that will be brought into the proposed Phase II research.

2. Purpose, Objectives, Scope

AguaClara research teams have already demonstrated efficient removal of arsenic using

PACl followed by direct filtration. This treatment scheme has the potential to significantly

reduce the costs of arsenic and possibly fluoride treatment to make safe drinking water more

affordable where contaminated groundwater is the best source of drinking water. Given that

aluminum sulfate is an effective coagulant in treating fluoride contaminated groundwater, Phase

I research applied similar chemical theory to a novel fluoride removal design. Other coagulants

such as PACl have exemplified superior performance compared to aluminum sulfate, and

previous research concluded that arsenic readily adsorbs to PACl (Zhi, 2015). Phase I would

confirm or disprove that fluoride similarly adsorbs to PACl precipitates. The experimental setup

used tap water contaminated with sodium fluoride (NaF) to simulate fluoride contaminated

groundwater. Current AguaClara groundwater treatment systems in India utilize a stacked rapid

sand filter (SRSF) as the finishing step to removing particles. A SRSF was incorporated into the

experimental design as a lab-scale filter column to simulate similar conditions. Based on the

Phase I results, this system has the potential to improve drinking water quality where there is

excessive fluoride contamination. The research addresses the global issue of groundwater

fluoride and arsenic contamination, with the goal of creating a sustainable and cost effective

treatment option.

3. Data, Findings, Outputs/Outcomes

Below are the modifications incorporated into the reactor system (Figure 2) as previously

outlined in the Phase I proposal:

● Substitute polyaluminum chloride (PACl) in place of aluminum sulfate. PACl may be

more efficient at fluoride removal than alum and will not add sulfate to the water.

● Use direct

filtration to obtain

better removal of

fluoride at a lower

coagulant dose and

thus lower

operating cost.

● Replace batch

processes with

continuous flow

processes.

● Use a hydraulic

rapid mix with a

high energy

dissipation rate to

obtain a more uniform distribution of aluminum hydroxide precipitate.

In the apparatus design, PACl and fluoridated ―raw water‖ solutions were sent through a

hydraulic rapid mix, then filtered by a laboratory-scale sand filter. A fluoride ion selective

electrode (ISE) probe was placed in the exit container to evaluate the effluent fluoride

concentration.

The reactor system was tested at a fluoride concentration of 10 mg/L to represent a relatively

high level of contamination. PACl

was added at 20, 40, and 50 mg/L

as Al. As expected, fluoride

removal efficiency increased with

PACl dose. A PACl concentration

of 50 mg/L brought the fluoride

concentration from 10 mg/L to

below the WHO standard of 1.5

mg/L, achieving around 86-94%

removal (Dao et al., 2015).

Fluoride concentrations in filtered

water over time in an experiment

at the 50 mg/L PACl dose are

shown in Figure 3. Fluoride

removal efficiencies at other PACl

doses are summarized in Table 1.

The 50 mg/L Al required using

PACl is much more efficient at

fluoride removal than the 1200

mg/L Al required when using

aluminum sulfate (Dahi et al., 1996).

Overall Evaluation of Success

Phase I research results exceeded our expectations. The high solubility of the fluoride ion had

led us to be somewhat skeptical of the feasibility of inventing an economically viable method for

Figure 2. Schematic of apparatus used in Phase I research using

direct filtration (Dao et al., 2015).

Figure 3. Effluent fluoride concentration using 50 mg/L

PACl and direct filtration. The hydraulic residence time

of the system was 12.3 minutes and the steady state

performance was approximately 85% removal (Dao et

al., 2015).

removal of fluoride using a

coagulant. To treat 20 L of

water per person for a 6

member household, it would

cost almost $50 per

household per month

(WHO, n.d.) using

aluminum sulfate. The

switch to a better coagulant

and to a continuous flow

system resulted in a

dramatic 24 fold

improvement in the

efficiency as measured by

the mass of aluminum

required per mass of

fluoride removed. Phase I

results indicate that this

technology has the potential

to serve the many

communities that suffer from dangerously high fluoride concentrations in their drinking water.

Progress Towards Sustainability

AguaClara water treatment systems are sustainable (Rivas, 2014) because they rely on a

locally available non-proprietary materials, community management, and local ownership.

Sourcing all necessary materials locally decreases costs and complexities of obtaining

replacement parts. Technologies that minimize failure modes directly translate into cost

efficiency and operational simplicity, so any community can independently maintain their water

treatment system. The AguaClara technologies developed for surface water treatment now

provide a technology platform that can readily be adapted to additional contaminants. The

gravity powered chemical dosing system, hydraulic flocculation, sedimentation, and stacked

rapid sand filtration are all potentially useful in the development of a high efficiency fluoride and

arsenic removal system.

4. Discussion, Conclusions, Recommendations

Elements of People, Prosperity, and the Planet

The challenge of sustainability for People, Prosperity, and the Planet was met in Phase I by

reducing the mass of aluminum required to treat fluoridated groundwater by a factor of 24. These

improvements pave a path for Phase II research to further reduce waste and simplify operation in

preparation for pilot testing. With a commitment to open-source engineering the team will

continue to foster self-sufficient, sustainable designs for communities that currently lack safe

drinking water.

The main health benefit of drinking water with safe levels of fluoride is a decrease in risk for

dental and skeletal fluorosis, especially in youth that are in the process of developing bone

Table 1: Fluoride removal as a function of PACl dose using direct

filtration (Dao et al., 2015).

Trial

Number

Coagulant

Dosage

(mg/L as

Al)

Influent

fluoride

concentration

(mg/L)

Effluent

fluoride

concentration

(mg/L)

Percent

Removal

1 20 8.9 3.7 58%

2 20 10.3 5.7 56%

3 40 10.8 1.75 84%

4 40 10.7 2 81%

5 50 10.3 1.40 86%

6 50 10.4 0.64 94%

structure. A healthy community of people improves overall welfare and increases productively in

each individual’s life. The improved method of fluoride removal can provide all these benefits to

communities in developing countries while keeping the environmental footprint small.

Since the improved fluoride treatment technique uses significantly less coagulant and

physical labor, this system is a cost-effective option for use both in the United States and

globally. It produces safe drinking water and protects people from harmful skeletal diseases in

areas where there is high fluoride contamination.

Quantifiable Benefit of the Project

India is home to more than 1.2 billion people, and more than 66 million people are at risk for

skeletal fluorosis due to fluoride contamination (Arlappa, 2013). AguaClara demonstrated that

fluoride contamination of 10 mg/L can be successfully treated using PACl in combination with

hydraulic rapid mixing and sand filtration. After treatment, the effluent fluoride concentration is

below the 1.5 mg/L WHO standard. This is all accomplished using a PACl coagulant dose that is

24 times less than the amount of aluminum sulfate required to treat the same concentration of

fluoride.

Adaptation of Existing Knowledge

The Nalgonda method was invented by the National Environmental Engineering Research

Institute in India in 1975 to combat fluorosis issues (Venkobachar, 1997). This technique was

intended to be carried out in batch processes and mixed by hand to simulate flocculation.

Aluminum sulfate is first added to the added to the water as a coagulant, and later lime is added

to enhance settling and raise the mixture back to a neutral pH. While the Nalgonda method is

effective at low fluoride contamination levels, problems arise when higher concentrations of

fluoride need to be removed. In order to precipitate the highly soluble fluoride ion, it is necessary

to use a concentration of aluminum sulfate as high as 1000 times the concentration of fluoride

present. After the treatment process is over, high dosages of aluminum sulfate leave an excessive

sulfate concentration, causing aesthetic concerns.

The prior experience of using PACl and direct filtration to remove arsenic (Zhi, 2015) led to

the hypothesis that a similar approach might work with fluoride. The continuous flow design of

the improved method eliminates the previous constraints set by batch treatment, use of PACl

proves to be a more efficient coagulant that does not leave residual taste issues, and sand

filtration assists in the removal of small colloidal (floc) particles.

Assurance Research Misconduct has not Occurred During Reporting Period

The guiding philosophy of our research is to understand physical/chemical mechanisms so

that we can design better water treatment technologies and expand the coverage of safe drinking

water to communities. Given that our primary objective is improved technologies, we have no

motivation to engage in research misconduct because we know that misconduct would only

confound our effort to make the world a better place. Instead students are encouraged to learn

from mistakes even when that means abandoning multi-year research programs when it becomes

clear that a technology will not be viable without significant breakthroughs. No research

misconduct has occurred during the reporting period. All information in this report is true, has

been reviewed by the authors, and all outside sources are cited.

B. Proposal for Phase II

Challenge Definition and Relationship to Phase I

The challenge of Phase I was to evaluate the efficiency of PACl coupled with direct filtration

for the removal of fluoride from groundwater. Phase I results demonstrate that a simple reactor

system with a PACl dose of 50 mg/L Al reduced the fluoride concentration from 10 mg/L to

approximately 1 mg/L. This aluminum dose is 24 times less than that used for the Nalgonda

method and this large reduction in reagent makes this system economically viable as a treatment

method.

The shortcoming of the direct filtration method evaluated in Phase I was that a PACl dose of

50 mg/L resulted in a filter head loss of 1 m in about 10 minutes (Zhi, 2015). At these high

coagulant dosages the head loss in sand filters was found to be directly proportional to the mass

of coagulant introduced into the filter. Filter runtimes measured in minutes are not viable

because filter backwash results in a substantial wasting of water unless a recycle system with the

associated pumping is used. The need for a relatively high PACl dose for efficient fluoride

removal and the correlations between accumulated coagulant mass in a filter column, head loss,

short filter run times, and water waste during backwash made it clear that direct filtration was not

an optimal solution for fluoride removal. However, direct filtration may still be applicable as a

polishing step if high fluoride concentrations can be reduced using an alternative reactor

configuration that is not susceptible to the accumulation of head loss that occurs in a filter.

Over the past decade the AguaClara program has developed a high efficiency sedimentation

tank that combines the three processes of floc blanket, sludge consolidation, and plate settlers.

The AguaClara

sedimentation tank

(Figure 4) is self-cleaning,

has no mechanized parts,

and creates a highly

concentrated (and hence

low flow) waste stream.

When applied to turbid

surface water treatment

the AguaClara

sedimentation tank

develops a floc blanket

with a concentration

between 2 and 5 g/L and

sludge that is

approximately 100 g/L

(Garland, 2015). The

sedimentation sludge concentration is approximately 1000 times more concentrated than typical

backwash water from a rapid sand filter. A highly concentrated fluoride waste stream will

simplify and reduce the cost of waste management. In addition the AguaClara sedimentation tank

is a continuous flow separation process that unlike a rapid sand filter does not need to stop for

cleaning.

Given the superior solids handling capabilities of a well-designed sedimentation tank, Phase

II will focus on developing design parameters for a fluoride removal system that incorporates

flocculation, sedimentation, and possibly filtration as a polishing step.

Figure 4. Cross sectional view of an AguaClara sedimentation

tank showing the floc blanket, plate settlers, and sludge

consolidation zones.

The proposed multi-step treatment train will require testing of multiple parameters to obtain a

robust design. The design parameters values for surface water treatment provide a point of

departure for Phase II research, but those parameter values are not expected to be optimal for

fluoride removal from a low turbidity groundwater. The proposed fixed and variable design

parameters to be tested are given in Table 2.

Table 2. Proposed fixed and variable parameters for Phase II research. Primary parameters are

highlighted in green. Secondary parameters for optimization are highlighted in yellow.

Parameter Symbol AguaClara

design

Proposed research range

(default)

Fluoride concentration CF NA 4 - 20 mg/L (10 mg/L)

PACl dose CPACl variable 10-100 mg/L as Al (50 mg/L)

Clay concentration CClay variable 0 - 2400 mg/L

Hydrogen ion concentration pH variable 7 - 8 (8)

Flocculator velocity gradient G 100 s-1

100 s-1

Flocculator residence time θ 400 s 40 - 400 s (400 s)

Floc blanket upflow velocity VUp 1 mm/s 0.5 - 1 mm/s (1 mm/s)

Plate settler capture velocity VC 0.12 mm/s 0.05 - 0.12 mm/s (0.12 mm/s)

Countercurrent Floc blankets in

series

NFB 1 1-3 (1)

Filter approach velocity VFi 1.85 mm/s 1.85 mm/s

Filter bed depth HFiLayer 20 cm 20 cm

The experimental protocol will progress systematically to explore the parameter space to

refine the optimal range of testing for each parameter. The critical parameters that are already

known to have a dramatic impact on system performance are PACl dose, clay concentration, and

floc blanket upflow velocity. We hypothesize that clay will be required to produce a floc blanket

with settleable flocs and a concentrated waste stream. For surface water treatment it isn’t

necessary to add clay. The clay/coagulant mixture along with flocculator characteristics

determine the floc blanket concentration. For high mass ratios of coagulant/clay the resulting

flocs have low sedimentation velocities and produce low floc blanket concentrations. At

extremely high mass ratios the resulting flocs are so sticky that they produce gel like structures

that can fill a laboratory scale sedimentation tank and that

is carried upward by the flow of water.

In a close analogy to agile software development

(Beck, 2001), the AguaClara program seeks to test new

technologies in the field as soon as appropriate. The

number of variables that must be tested is large and it is

likely that sedimentation tank geometry may need to be

modified to handle larger and stickier flocs. Reactor

construction is facilitated by collaboration with the

School of Civil and Environmental Engineering’s

machine shop. The AguaClara laboratory has advanced

software capabilities for automation of experiments that

facilitate systematic variation of parameters to find

improved designs. The Process Control and Data

Acquisition (ProCoDA) software and hardware makes it

possible to systematically vary one or multiple

parameters while continuously monitoring performance.

ProCoDA will be used to accelerate exploration of the

parameter space to improve the cost effectiveness and

efficiency of the treatment process. The sludge

production rate will be measured with grab samples as

total suspended solids.

Preliminary Results

Preliminary experimentation with the floc blanket

reactor (Figure 5) yielded 61% fluoride removal using a

PACl concentration of 25 mg/L as Al and approximately

85% fluoride removal using a PACl concentration of 50

mg/L as Al (Figure 6). In Phase II, parameters and

reactor design will be varied to achieve a consistently

well performing system.

Proposal Quality

Innovation and Technical Merit

Phase I research has demonstrated the potential of a novel fluoride and arsenic removal

technology that uses a readily available and low cost coagulant. PACl is manufactured in India

and is widely available. The proposed Phase II research is designed to reduce labor costs,

Figure 5. Continuous flow floc

blanket reactor system proposed

for Phase II research. The

AguaClara sedimentation tank is

modeled by the vertical

sedimentation tube, 45 degree

upward branching tube settler and

45 degree downward angled floc

hopper shown on the right side.

minimize coagulant use, and minimize

the waste stream containing the

contaminants. Labor will be reduced by

using a floc blanket reactor to create a

continuous tiny flow of highly

concentrated waste. If a filter is

included in the treatment train the filter

run time will be long due to the very

low turbidity exiting the plate settlers of

the sedimentation tank. A

countercurrent reactor system with

multiple floc blankets will also be

tested to further reduce the amount of

coagulant required. The reactor design

will be published and shared on the

AguaClara design webpage (AguaClara

Design, 2016)

Expected Outputs and Results

The deliverables will be a working

laboratory scale fluoride removal

reactor, a published design and

fabrication method for a pilot scale

fluoride removal reactor, preliminary

pilot scale testing with our partners, and

research reports and papers submitted

on this new method of fluoride

removal.

Engagement with Local Communities

As part of the AguaClara RIDE

philosophy, we work with partner

organizations that have expertise in

implementing water treatment

technologies at the community scale. Our partners teach community members how to maintain

their own treatment plants and convey the importance of safe drinking water on tap. Over the

past decade AguaClara has developed a suite of new technologies that have been transferred to

Honduras and India. There are currently 12 operating AguaClara plants in Honduras and 4 pilot

projects in India. The long term sustainability of the AguaClara technologies in Honduras is a

direct result of an ongoing, trust-based relationship with the partner organization and the

community leaders. AguaClara LLC and the Tata Cornell Initiative will provide guidance on

when it is appropriate to begin a pilot system test in India in preparation for deployment in

villages.

Grant Fund Expenditure Plan

The AguaClara program uses a team organization that includes purchasing support from an

experienced graduate student, a student leadership team, and a group of student research advisors

who train new team members in the R&D methodologies that we have developed over the past

Figure 6. Effluent fluoride concentration using 25

mg/L PACl (top) and 50 mg/L PACl (bottom) and

the fluidized floc blanket reactor. The hydraulic

residence time of the system was 19 minutes and

the steady state performance was approximately

61% removal at 25 mg/L and 85% removal at 50

mg/L.

decade. In addition, Cornell administration provides controls to ensure that grant funds are

expended appropriately and in an efficient manner using an online shopping portal. The PIs will

guide the project teams to ensure that the project addresses the most important research tasks, is

agile in responding to new information, and stays on schedule.

Ensuring Successful Achievement of Project Objectives

The AguaClara innovation system relies on mentoring, feedback, rapid prototyping and

testing, a collaborative team based laboratory where learning opportunities are maximized, and

robust systems exist for experimental design, data collection, and analysis. The team has

developed an excellent understanding of the physics of particle-particle-fluid-reactor geometry

interactions and the ability to design reactors for fluidized beds of fractal flocs that adsorb

fluoride.

The AguaClara laboratory includes state of the art process control and data acquisition. The

student research teams have workstations in a collaborative laboratory with a mix of experts and

novices. The team has extensive design and research experience with chemical dosing, rapid

mix, flocculation, floc blankets, sedimentation, and filtration. These platforms well be used as a

basis for additional innovations required for an efficient fluoride removal reactor.

Overall Sustainability

The low operating cost, simple operation, and ultra-low energy requirements of the proposed

fluoride removal reactor are expected to make it a competitive technology both in the US and

internationally. Ease of fabrication and operation allow the system to be built using locally

available materials and operated by trained community members. The proposed phase II research

would create an efficient fluoride removal treatment process that is well-suited for

implementation in rural communities.

Environmental Sustainability

The proposed fluoride removal method will reduce coagulant use by a factor of

approximately 24 for the removal of fluoride from water compared with the Nalgonda method.

The proposed method has a very high probability of also being applicable for the removal of

arsenic and thus could be helpful in reducing exposure to another environmental toxin. The

fluoride removal method does not require any electricity or mechanical mixing in the treatment

processes. Chemical addition will use the chemical dose controller that was invented in a

previous EPA P3 project. Rapid mix and flocculation will use approximately 40 cm of water

surface elevation decrease. The floc blanket and sedimentation tank require less than 10 cm of

water surface elevation decrease. The stacked rapid sand filter uses about 1 m of water surface

elevation drop to produce very high quality water. The overall treatment process will use

approximately 14 Joules of energy per liter of water produced. This does not include pumping

that will be required to lift water from a well to a village.

The addition of a high efficiency sedimentation tank will decrease the amount of wastewater

produced by the process. The dominant source of waste water from the fluoride removal process

will be filter backwash water if a filter is needed. It is possible to recycle backwash water and

thus only produce a highly concentrated sludge from the sedimentation tank. The addition of clay

will result in an increase in sludge production and our phase II research will focus on minimizing

the amount of clay required to produce a stable floc blanket.

Social Sustainability

AguaClara works with partners who in turn work with local communities to ensure long term

sustainability (Rivas et al., 2014). The 12 municipal water treatment plants designed by

AguaClara in Honduras demonstrate the power of the network and the commitment of

communities to responsibly manage their water supply systems. The AguaClara program

recognizes the power of engineering in collaboration with the communities.

Gaining community trust is a prerequisite for social sustainability. For this reason, AguaClara

takes the R&D stage of technology development very seriously and does not rush to implement

new technologies.

Economic Sustainability

The low cost and easy maintenance of current AguaClara treatment technology makes it an

economically sustainable option for communities in the developing world. Water treatment

plants are dependent on the tariffs that are collected from community members. In the United

States, we are usually fortunate to have access to high quality clean water at costs that are low

compared to the average income. Economic sustainability for communities with lower incomes

requires very low operating costs and that, in turn, requires more investment in R&D.

Education and Teamwork

The Cornell AguaClara program provides students the opportunity to invent new

technologies while learning fundamental engineering principles and engaging with partner

organizations including Agua Para el Pueblo in Honduras, AguaClara LLC and the Tata Cornell

Agriculture and Nutrition Initiative in India. Every year, students are given the opportunity to

visit Honduras and see first-hand the impact these water treatment systems are making in rural

towns. The proposed Phase II research will provide an opportunity for a team of students to

transfer the technologies they helped to develop to the partner organizations in India.

The AguaClara program provides a safe place for student teams to practice real engineering in an

environment where they have ready access to experts and mentors. Additionally, AguaClara also

draws awareness to the topic of clean drinking water by attending events such as the Social

Impact Conference and National Sustainable Design Expo. The achievements of AguaClara and

other sustainable design initiatives continue to impact those of the local Cornell community and

across the world.

Students come from environmental, chemical, civil, and mechanical engineering, city and

regional planning, and Cornell’s business college. Graduate students from City and Regional

Planning gain understanding of the resources required to construct a successful treatment system.

Students from the School of Hotel Administration contributed marketing strategies to help

AguaClara establish a global presence. With local implementation partners, AguaClara can

empower these villages with the knowledge and technology to be self-sustaining. The AguaClara

network includes Agua Para el Pueblo (a Honduran NGO), AguaClara LLC (fostering the spread

of AguaClara technologies to new regions), and Cornell Social Business Consulting. The

international presence and partnerships AguaClara has creates a learning environment for

students that encourages them to make future changes. After graduating, team members have the

opportunity to work in developing countries on implementing AguaClara technology. Teamwork

with the local community is an essential step to provide safe drinking water to any community.

Project Schedule

Spring 2016 This semester, the research team is focusing on designing a reactor system that is

adapted from the current AguaClara floc blanket sedimentation tank design. They will evaluate

the effects of using a floc blanket in precipitating fluoride and enhancing flocculation. Results

will be evaluated over different combinations of PACl dose and influent fluoride concentrations.

Fall 2016 Test the clay concentration required to achieve a continuous flow sedimentation tank

with a floc blanket. ProCoDA will use a Proportional, Derivative, Integral (PID) feedback

algorithm to control the influent turbidity by varying the flow of a clay stock. The floc blanket

upflow velocity may be varied to accommodate lower clay concentrations. Explore floc blanket

upflow velocity and reactor geometry to reduce the amount of clay required.

Spring 2017 Test 2 or 3 counter current floc blanket reactors in series to optimize efficiency of

coagulant use. In this reactor design the coagulant would be added to the final floc blanket in a

series of reactors and then the floc hopper discharge would be returned to the upstream floc

blanket. This process would be repeated for each floc blanket reactors in the series. This reactor

design would have the advantages of being able to achieve efficiencies comparable to plug flow

systems even though the flocs in a floc blankets are close to completely mixed over the time

scale of the residence floc residence time. Assess the value of the efficiency gains vs the more

complex reactor geometry. Evaluate methods to simplify the countercurrent reactor geometry

Fall 2017 Optimize PACl dose as a function of fluoride concentration using the reactor

configuration selected in the spring of 2017. Assess the need for a filter given that municipal

scale AguaClara sedimentation tanks routinely achieve settled water turbidity well below 2 NTU

(OpenSourceWater, 2016). ProCoDA will be used to measure settled water turbidity using an

HFScientific inline turbidimeter. Begin designing a pilot scale fluoride removal facility. Evaluate

sites for pilot scale testing in collaboration with TCi and AguaClara LLC. Maintain a

conversation with AguaClara LLC engineers in India and the Tata-Cornell Agriculture and

Nutrition Initiative (TCi) to evaluate the status of our research and to assess the minimum

requirements to begin testing the technologies at pilot scale in India.

Spring 2018 Continue testing and iterating on reactor design, coagulant feed, and clay feed.

Fabricate 0.1 L/s pilot scale facility at Cornell and document all fabrication steps.

Summer 2018 Fabricate and set up pilot scale facility in India in collaboration with TCi and

AguaClara LLC. Test performance, propose design changes prior to piloting in a community and

explore funding opportunities for deployment of the first village scale treatment system.

Quality Assurance Statement

The PIs have over 40 years of drinking water treatment research experience and have been

guiding student research/invent/design/engage teams since founding the AguaClara program in

2005. The ProCoDA (Process Control and Data Acquisition) software that is used by the student

teams to automate the control of experimental apparatus and to collect real time data from

sensors and meters was authored by one of the PIs. The primary parameters required to evaluate

fluoride removal system performance are filter head loss (pressure sensor), turbidity (HF

Scientific online turbidimeter), and fluoride ion selective electrode. These data sources will be

captured by the ProCoDA software and logged to a shared drive with backup protection.

Peristaltic pumps are used to meter flows and the flows are verified using an electronic balance

and stopwatch.

The data sources required for this research are routinely used in the AguaClara project

laboratory and thus method development is routine. Turbidimeter calibrations are performed

based on the manufacturer's’ requirements. Pressure sensor accuracy is checked using measured

depths of water. The fluoride probe is calibrated daily using calibration standards. Analysis and

organization of data is required for the bi-weekly reports that each team submits. Additionally,

project data is organized in a shared computer drive that can be easily accessed by Cornell

students. Reports are posted on the AguaClara wiki at

https://confluence.cornell.edu/display/AGUACLARA/Home. Students regularly schedule online

meetings with engineers in Honduras and India and in-person meetings with project team

advisors to assure they are on track to meeting project goals and that the data is correctly

analyzed and interpreted.

Partnerships

The AguaClara program at Cornell has ongoing collaborative partnerships with Agua Para el

Pueblo in Honduras (since 2005) and AguaClara LLC (since 2012) and Tata Cornell initiative

(since 2013) in India. These partners are committed to deploying new AguaClara technologies as

they are developed, designed, and demonstrated at lab scale.

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