P a g e | 1

X Y L E M

MECHANICAL ENGINEERING 310 DOCUMENTATION 2018-2019

Mechanical Engineering Design Group 416 Escondido Mall Stanford University Stanford, CA 94305- 2203 http://me310.stanford.edu

Team Xylem:

Adit Desai Fay Nicole Colah Okkeun Lee Tin Jing jie

Dai Jiang Mika Julin Nina Saarikoski Samuel Moy Timo Moyer 1 Executive Summary

This report summarizes the work completed by the Stanford University (SU) and Aalto University (AU) Teams during the 2018-19 Academic Year for ME310 with our corporate sponsor Xylem Inc. In Autumn Quarter 2018, the SU team explored the concept of a modified drip irrigation system designed to reduce the amount of water lost due to evaporation during irrigation, and an oyster based water filtration system which aimed to replicate the mucus in oysters to trap contaminants to purify water. In Winter Quarter 2019, the SU team explored the concept of a human powered personal and floor-based filtration system, which achieved flow rates of up to 80 times faster as compared to gravity fed methods. In Spring Quarter 2019 after the Winter Break in Aalto University, the SU and AU teams converged on a final product design concept and user, which was a low cost, modular and highly maintainable water filtration system which could remove heavy metals, pathogens and sediments from contaminated waters. The filtration system was designed such that clean drinking water could be provided to rural children in developing countries who did not have access to an electrical supply. A key nature-inspired filtration technology of this system was the usage of microalgae (Chlorella Vulgaris) for batch removal of heavy metals, where literature research reported that small quantities of such algae are able to remove significant quantities (~88%) of heavy metals from contaminated waters within 30 minutes. Lead removal testing conducted by Jessica Moyer, Xylem’s corporate contact, with assistance from the SU team with low algae biomass concentrations reported that more than 50% of all Lead in water was absorbed within an extremely low contact time of less than 5 minutes. This brings Lead concentrations in water to acceptable drinking water standards in developing countries such as India, where the low cost of Chlorella Vulgaris ($0.73/kg) and effective heavy metal removal makes algae a sustainable, long term solution to the drinking water needs of our rural users. A second key feature of the final product is the processing and treatment of algae after heavy metal adsorption through the usage of natural bio-flocculants such as Chitosan, which require 5 times less mass than traditional flocculants to aggregate algae cells into large flocs which settle to the bottom of the dirty water tank. With 0.25g/L of Chitosan added, 90% biomass removal was achieved in 10 minutes which prevents Lead-filled algae from entering the main filtration system, therefore reducing maintenance and backwash requirements for the system. A third key feature is the usage of human power to accelerate the flow rate of contaminated water through the product’s filtration system, where a foot based water pump operated by the user provides high pressure to the water stream in the system for high flow rates. The usage of human power allowed the SU and AU teams to avoid using gravity-fed methods and create a highly compact and modular system for user ease of use and maintenance. The AU team focused on developing the mechanical filtration aspects of the system by specifying the micro and sediment filters to be used. Another key aspect of the final product is the simple backwash mechanism, where the connection of a backwashing syringe to the backwash inlet of the system and the turning of 2 taps to backwash form the only requirements which the user has to meet in order to perform backwash. This makes backwashing simple and easy to carry out by the user to ensure that the filtration systems would be regularly maintained by the user. Finally, water flow rate tests on the entire system with sediment filter, micro filter and GAC in place found that a decent flow rate of 40ml/step was achieved with each user step. Hence to meet the daily drinking water requirement of 1L/day, a low step count of 25 is needed for each child. Therefore, the SU and AU teams have designed a low cost, modular and easily maintainable system which can remove sediments, pathogens and heavy metals from contaminated water while delivering a good flow rate for our user.

Figure 1. Team Xylem- STEP2O Section 3 of this report documents the design development process, while Section 4 documents the design requirements of the final product. Section 5 documents the design specifications of the final product and test results, section 6 documents project management by the SU and AU teams, and section 7 documents the reflections by individual members of the SU and AU teams.

Glossary

Word Definition AU Aalto University Backwash The process of reversing water flow through a mechanical filtration system to remove dirt and particles from the filter Batch filtration The removal of heavy metals by adding microalgae into batches of contaminated water Bioadsorption A physiochemical process that occurs naturally in certain biomass which allows it to passively concentrate and bind contaminants onto its cellular structure. Bioaccumulation The gradual accumulation of substances, such as pesticides, or other chemicals in an organism Bio-Flocculent A biological substance which is used to aggregate smaller particles in water together into larger clumps, which then settle to the bottom of water tanks by virtue of their larger mass Biomass Dry mass of microalgae per litre of water concentration Capillary Action The tendency of a liquid in a capillary tube or absorbent material to rise or fall as a result of surface tension Chitosan A sugar that is obtained from the hard-outer skeleton of shellfish, including crab, lobster, and shrimp. In this project, Chitosan was used as a bio-flocculent Continuous Filtration The removal of heavy metals by continuously passing water through a microalgae filter Chlorella Vulgaris Species of Micro-algae used to remove heavy metals in this project Critical Experience A prototype used to answer questions about how the users might Prototype (CEP) respond to aspects or elements of a design. One primary purpose of a CEP is to explore a possible design direction Critical Function A prototype that addresses the performance of a critical component of Prototype (CFP) a system. One primary purpose of a CFP is to explore a possible design direction Dark Horse Prototype A prototype that intentionally diverges from the current vision focus (DHP) to explore marginalized design themes. Desalination A process that takes away mineral components from saline water. More generally, desalination refers to the removal of salts and minerals from a target substance Filtration The process of removing small particles from water through a mechanical filter Filter feeding a form of food procurement in which food particles or small mechanism organisms are randomly strained from water Float Valve A one-way valve that is opened and closed by pressure on a ball which fits into a cup-shaped opening Functional Prototype A system prototype that pivots a project direction into the (FcP) convergence phase and can provide a silhouette of what the final product should look like. The CFP helps tease out technical and implementation issues as well as more clearly define the project scope. Funk-tional Prototype A low fidelity prototype for which existing parts have been hacked (FkP) and brought together in a manner that approximates a system without making a costly commitment to any one configuration, technology, or geometry. Granular Activated Chemical filter system which removes taste and bad odour by Carbon (GAC) Filter absorbing chemicals from contaminated water Gravity-fed methods A commonly used filtration method where gravity is used to force water through filtration systems at accelerated flow rates Gravity and Bio-sand A point-of-use water treatment system adapted from traditional slow Filters sand filters. bio sand filters remove pathogens and suspended solids from water using biological and physical processes that take place in a sand column covered with a biofilm Heavy Metals Any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations Hollowfibre Mechanical filter system with pore sizes of about 0.1 microns which membrane micro removes pathogens from contaminated water filter Ion exchange The process of replacing a H+ ion with a positively charged heavy metal ion in the functional groups in microalgae cell walls Micro-Algae Found in freshwater and marine systems, living in both the water column and sediment. They are unicellular species which exist individually, or in chains or groups. Microplastics Small plastic pieces less than give millimetres long which can be harmful to ocean and aquatic life Pathogens A bacterium, virus, or other microorganism that can cause disease. Part X The completion of a non-trivial part of the design in its final form PPB Parts per Billion Reverse Osmosis A process by which a solvent pass through a porous membrane in the direction opposite to that for natural osmosis when subjected to a hydrostatic pressure greater than the osmotic pressure Radial Filter A filter that takes in water from the circumference of the filter Sediment Filter Mechanical filter system with pore sizes of about 5 microns meant to prevent larger particles from entering the main filtration system SU Stanford University Turbidity A measurement of the cloudiness of a liquid solution. Using microcontroller sensors, turbidity is a measurement of the amount of light reflected from suspended particles

Table of Contents

1 Executive Summary 2 Context ...... 1 2.1 Corporate Context ...... 1 2.1.1 Xylem Inc...... 1 2.1.2 Corporate Liaison...... 3 2.1.3 Stanford University Teaching Team ...... 4 2.1.4 Aalto University Teaching Team ...... 6 2.2 Problem Statement ...... 7 2.3 Teams ...... 8 2.3.1 Stanford University ...... 8

2.3.2 Aalto University ...... 12 3 Design Development ...... 16 3.1 ME 310 Kick-Off ...... 16 3.2 Fall Quarter ...... 16 3.2.1 Desalination ...... 16 3.2.2 Underground Irrigation ...... 17 3.2.3 Xylem Based Water Filtration ...... 18 3.2.4 Oyster Based Water Filtration ...... 18 3.3 Winter Quarter...... 19 3.3.1 Microplastics Detection ...... 20 3.3.2 Dark Horse 1: Human Powered Personal Water Filtration ...... 21 3.3.3 Dark Horse 2: Pipe Leak Detection and Repair Robot ...... 22 3.3.4 Funktional Prototype ...... 23 3.3.5 Functional Prototype ...... 24 3.4 Spring Break ...... 26 3.5 Spring Quarter ...... 27 3.5.1 Need finding...... 27 3.5.2 Choice of User ...... 28 3.5.3 Benchmarking Technologies ...... 29 3.6 Our Design Vision ...... 33 3.7 Algae Concept Development ...... 33 3.8 Algae Cultivation ...... 34 3.9 Initial Design ...... 34 3.9.1 Part X ...... 35 3.10 Design Changes ...... 36 4 Design Requirements ...... 38 4.1 Functional Requirements...... 38 4.2 Functional Constraints...... 40 4.3 Functional Opportunities ...... 40 4.4 Functional Assumptions ...... 41 4.5 Physical Requirements ...... 41 4.6 Physical Constraints ...... 42 4.7 Physical Opportunities ...... 42 5 Design Specifications...... 43 5.1 System Description ...... 43 5.2 System Overview ...... 46 5.2.1 Bio-Adsorption of Heavy Metals ...... 46 5.2.2 Mechanical and Chemical Filtration ...... 49 5.2.3 Human Powered Pumping System ...... 53 5.2.4 Filter Backwash ...... 57 5.3 Final Product Testing and Performance ...... 59 5.4 User Testing ...... 61 5.5 Business Model ...... 61 5.6 Future Plan ...... 62 6 Project Management ...... 63 6.1 Distributed Team Management ...... 63 6.2 Communication: ...... 63 6.3 Role Distribution between Team Members ...... 63 7 Team Reflections ...... 65 7.1 Adit Desai ...... 65 7.2 Fay Nicole Colah ...... 65 7.3 Okkeun Lee ...... 65 7.4 Tin Jing Jie ...... 66 7.5 Dai Jiang ...... 66 7.6 Samuel Moy ...... 67 7.7 Timo Mayer ...... 67 7.8 Mika Julin ...... 67 7.9 Nina Saarikoski ...... 68 8 Bibliography ...... 69 APPENDIX A- CAD Images APPENDIX B- EXPE Presentation APPENDIX C- EXPE Brochure APPENDIX D- EXPE Posters APPENDIX E- Part X Handout APPENDIX F- Initial Manufacturing Plan

List of Figures

Figure 1. Team Xylem- STEP2O ...... 3 Figure 2 Xylem Inc. Branches of Operation ...... 1 Figure 3 Xylem Inc. Products ...... 2 Figure 4 Jessica Moyer ...... 3 Figure 5 Everaldo Ferreyra ...... 3 Figure 6 Mark Cutkosky ...... 4 Figure 7 Larry Leifer ...... 4 Figure 8 George Toye ...... 4 Figure 9 Austen Poteet ...... 5 Figure 10 Kirsten Seagers ...... 5 Figure 11 Salvador Perez ...... 5 Figure 12 Markku Koskela ...... 6 Figure 13 Joana Moreira ...... 6 Figure 14 Adit Desai ...... 8 Figure 15 Fay Nicole Colah ...... 9 Figure 16 Okkeun Lee ...... 10 Figure 17 Tin Jing Jie ...... 11 Figure 18 Dai Jiang ...... 12 Figure 19 Samuel Moy...... 13 Figure 20 Timo Mayer ...... 14 Figure 21 Mika Julin ...... 14 Figure 22 Nina Saarikoski ...... 15 Figure 23 Desalination Prototype ...... 16 Figure 24 Irrigation Prototype ...... 17 Figure 25 Xylem Based Filtration Prototype ...... 18 Figure 26 Oyster Based Filtration Prototype ...... 19 Figure 27 Microplastics Detector ...... 20 Figure 28 Working Principle of Human Powered Water filtration...... 21 Figure 29 Pumping System ...... 21 Figure 30 Filtration System ...... 21 Figure 31 Working principle of Pipe Repair and detection Robot ...... 22 Figure 32 Circuitry for the prototype ...... 22 Figure 33 Pipe Repair Robot Structure ...... 22 Figure 34 Floor Based Air Cushion ...... 23 Figure 35 Filtration System ...... 23 Figure 36 Entire Prototype ...... 24 Figure 37 Personal Foot pump ...... 25 Figure 38 Air Cushion ...... 25 Figure 39 Common Filtration Module ...... 25 Figure 40 Heavy metals in Chhattisgarh in India ...... 27 Figure 41 Gravity and Bio Sand filters ...... 29 Figure 42 Treatment efficieny of the product as the bio layer develops ...... 30 Figure 43 Ceramic filters ...... 30 Figure 44 Katadyn Filter ...... 31 Figure 45 Aquaduct...... 32 Figure 46 PlanetWater's AquaTower ...... 32 Figure 47 Chlorella Vulgaris ...... 34 Figure 48 Layout of Initial Design ...... 35 Figure 49 Initial Design concept ...... 35 Figure 50 Part X ...... 36 Figure 51 Part X concept ...... 36 Figure 52 Our Final Product ...... 43 Figure 53 Process of Operation...... 45 Figure 54 Ion Exchange in Algae ...... 46 Figure 55 Algae, Chitosan and Flocculated Algae ...... 48 Figure 56 0.5-micron filter ...... 49 Figure 57 Working of 0.5-micron filter ...... 49 Figure 58 Hollow Fiber Membrane Structure ...... 51 Figure 59 Cross Section of Hollow Fiber membrane ...... 51 Figure 60 Hollow fiber Membrane ...... 52 Figure 61 Granular Activated Carbon Filter ...... 53 Figure 62 Whale Baby Foot pump ...... 53 Figure 63 Cross Section of Foot Pedal ...... 54 Figure 64 Piping Diagram ...... 55 Figure 65 Normal operation ...... 56 Figure 66 Backwash Operation ...... 58 Figure 67 Removal of Algae through filter ...... 60 Figure 68 User Testing conducted by Aalto University ...... 61 Figure 69 Gantt chart for Spring Quarter ...... 64

List of Tables

Table 1 Functional Requirements ...... 38 Table 2 Functional Constraints ...... 40 Table 3 Functional Opportunities ...... 40 Table 4 Functional Assumptions ...... 41 Table 5 Physical Requirements ...... 41 Table 6 Physical Constraints ...... 42 Table 7 Physical Opportunities ...... 42 Table 8 Heavy Metal Adsorption by Algae ...... 47 Table 9 Flow through filtration stages ...... 60

P a g e | 1

2 Context

2.1 Corporate Context

2.1.1 Xylem Inc.

Xylem is one of the world’s leading water technology company aiming to ”solve water” by ”creating innovative and smart technology solutions to meet the world’s water, wastewater and energy needs”. Xylem develops ground breaking solutions across the life cycle of water: from collection and distribution to reuse and return to nature. Their highly efficient water technologies, industrial pumps and application solutions not only use less energy and reduce life-cycle costs, but also promote sustainability. Xylem Inc. is a leading provider of premium field, portable, online and laboratory analytical instruments and software serving water and wastewater, ocean/coastal, food and beverage, environmental, chemical and pharmaceutical markets. The company does business in over 150 countries. Its headquarters is in Rye Brook, New York and was launched in 2011. The company was formed when its parent company, ITT Corporation decided to split the company into three stand-alone publicly traded independent companies. Xylem has a market capitalization of 12.49 billion and had a revenue of 4.7 billion in 2017. Xylem works towards improving the situation in countries where water is scarce. Recently, Xylem signed a Memorandum of Understanding with Ethiopia’s Ministry of Water, Irrigation and Energy for future cooperation to help advance water security in Ethiopia. The company also recently announced that it would work with Manchester City football team as part of their corporate social responsibility to six different causes, one of which involves increasing access to safe water in Bangalore, India. Xylem provides products and services in two major areas i.e. water infrastructure and applied water. Water infrastructure involves wastewater transport and treatment, dewatering and analytical instrumentation.

Figure 2 Xylem Inc. Branches of Operation P a g e | 2

Xylem’s products include systems for treatment of water, pumps and pumping systems, heat exchangers, hydro turbines, wastewater treatment products, etc. They manufacture submersible pumps, axial flow pumps, self-priming pumps, positive displacement pumps, fire pumps and submersible hydro turbines. Their waste treatment products involve aeration equipment, biological wastewater and water treatment, sludge collection and monitoring and control equipment. Some of the products manufactured by them are shown in the figures below

Figure 3 Xylem Inc. Products P a g e | 3

2.1.2 Corporate Liaison

2.1.2.1 Jessica L. Moyer Senior Scientist, Advanced Technology and Innovation Team, Xylem Analytics at Xylem Inc SCIENTIST, ENVIRONMENTALIST. “Solving the world's most challenging problems through research and development of innovative sensing and instrumentation technology, empowerment of citizen science initiatives, support of local and global outreach, and inspiration of the next generation of problem solvers.”

Figure 4 Jessica Moyer 2.1.2.2 Everaldo Ferreyra Advanced Materials Principal Engineer in Xylem. Senior Materials Engineer with business goal acumen and nineteen years of experience working for leading global companies in the Automotive, Construction and Forestry Machinery and Water Technology and Service industries. Superb and cutting edge technical, analytical and problem solving skills come from corporate paradigm shifting search, R&D experience, material technology development and implementation on manufacturing plants around the world. Figure 5 Everaldo Ferreyra P a g e | 4

2.1.3 Stanford University Teaching Team

2.1.3.1 Mark Cutkosky Email = [email protected] Mobile (USA) = +1 650-889-8961

I was most impressed by the Design Group at Stanford and their understanding of the art of engineering. Today, while I profess to do research in bioinspired robotics, tactile sensing and dexterous manipulation, it's really the design challenges in each of these fields that turn me on. Figure 6 Mark Cutkosky

2.1.3.2 Larry Leifer Email: [email protected] Larry Leifer is a Professor of Mechanical Engineering Design and founding Director of the Center for Design Research (CDR) at Stanford University. He has been a member of the faculty since 1976. His teaching-laboratory is the graduate course ME310, "Industry Project Based Engineering Design, Innovation, and Development."

Figure 7 Larry Leifer

2.1.3.3 George Toye Email: [email protected]. George Toye has been professional engineer, designer, researcher, consultant, entrepreneur, manager, and executive. He is a self-professed technology junkie. Given wide diversity of interests and an insatiable longing to keep learning different things, his professional work has been diverse. A sampling of his breadth of experience earlier on in his career include: researching design knowledge capture and sharing tools, Figure 8 George Toye

P a g e | 5

2.1.3.4 Austen Poteet Status: 2nd year Stanford M.E. Graduate Student Email = [email protected] Phone = +1 704-607-8275

Figure 9 Austen Poteet

2.1.3.5 Kirsten Seagers

Status = 2nd year Stanford M.E. graduate student Email = [email protected] Phone = +1 484-883-5925

Figure 10 Kirsten Seagers

2.1.3.6 Salvador Perez

Status = 2nd year Stanford M.E. graduate student Email = [email protected] Phone = +1 951-427-7734

Figure 11 Salvador Perez P a g e | 6

2.1.4 Aalto University Teaching Team

2.1.4.1 Markku Koskela Status = Aalto University Lecturer & ME310 Aalto Program Coordinator Email = [email protected] Phone = +358 50 408 1760.

After completing ME310 as a student myself in 2009-2010, I’ve been teaching the program at Aalto University since January 2013.

Figure 12 Markku Koskela

2.1.4.2 Joana Moreira

ME310 Aalto Coach, Teaching Assistant - Aalto University Email= [email protected]

Figure 13 Joana Moreira P a g e | 7

2.2 Problem Statement

The company believes in pushing the designs of their products to achieve higher performance, longer life, better usability and cost effectiveness. Xylem, derived from Classical Greek, is the tissue that transports water in plants. This highlights the engineering efficiency of their water centric business by linking it with the best water transportation seen- that which occurs in nature. The student team which includes students from Stanford University, USA and Aalto University has been given the following prompt: How can nature inspire the next generation of water treatment, transport, or analysis technologies? P a g e | 8

2.3 Teams

2.3.1 Stanford University

2.3.1.1 Adit Desai

Figure 14 Adit Desai Status = 1st year Stanford M.E. graduate student Email = [email protected] Phone = +1 650-451-8903 Hi. I am a master’s student in the ME department at Stanford. I am from a small-ish town in western India. My only formal work experience was an internship at Bosch Rexroth in Germany. I worked on mechatronic training stations. Informally, i have participated in design competitions, made many projects and unique contraptions. I am passionate about a lot of things but my major interests include cars, tennis and guitar. And coffee. Aaand hiking. I have always been into creating interesting prototypes. I worked on creating a practical Petro-electric hybrid motorcycle and a handwriting machine (inspired by undergrad homework). By taking ME310 I want to sharpen my design and prototyping skills while also gaining an ability to generate a wide range of solutions for the same problem. Working with a team and managing its dynamics is also an interesting experience I intend to get out of ME310. The course is also closely aligned with what i enjoy about engineering and design. I would say i bring a general ability to break out of my comfort zone to work on projects that cover different disciplines. I enjoy reading up on something new and creating my own perspective on the topic. I also bring experience in engineering and mechatronics. I can also contribute by converting an idea into a drawing. I work well with people and machines. Specifically, I have worked with Arduino, PLC's, stepper motors, 3d modelling (fusion 360, Solidworks), power tools and dabbled in machine learning. P a g e | 9

5 years from now i hope to have my own automotive startup, after gaining some experience in the industry. I imagine myself converting my interests into my profession. I also see myself doing some amateur racing on the weekends. 2.3.1.2 Fay Nicole Colah

Figure 15 Fay Nicole Colah Status = 1st year Stanford M.E. graduate student Email = [email protected] Phone = +1 510-283-3456

Born and brought up in Mumbai, India. I completed my undergrad from University of Mumbai. I plan to specialize in Fluid Mechanics during my time here at Stanford. I was a part of the Aero-design team and designed and manufactured a remote-controlled aircraft during my undergrad. I also designed a small-scale wind tunnel as part of my thesis. I’ve interned with Air India Engineering Services Ltd. during which I worked on Pratt and Whitney engines used in aircrafts. I've also worked on Airbus and Boeing aircraft maintenance. I played soccer and dodgeball in high school. My free time involves walking dogs, baking cookies and cupcakes, listening to Coldplay and watching a lot of movies. ME310 involves working on something completely different than what I am used to. Coming to the US for my grad studies brought me out of my comfort zone. I made that decision so that I can experience new places and new people. There are new challenges involved in ME310, and a chance to be the best at some new skill every day. I want to grab onto these chances and make the best of the two years at Stanford. This is why I decided to take on ME310. I believe that the technical knowledge from my undergraduate and graduate studies will help in design. As I have experience in working on Lathe Machines and on power tools, I can help in prototype building. I also have some experience in CADD software. I have also taken the lead in a lot of projects during my undergraduate studies. My ability to P a g e | 10 think of different ideas to execute during prototype design and manufacturing has helped me during my research in my undergraduate studies. I believe I can do the same for this course. 5 years from now, I wish to see growth in terms of a technical aspect and a social aspect. I wish to tackle industry-based problems. I am not sure when I may start with my Ph.D., (maybe not), but I just wish to be confident enough to take up the challenge that comes my way. It may be a job at an industry or some research work in a professor's laboratory, but the primary goal is to be able to have the capacity to get past any difficulties that I have. I hope this course helps me inculcate the right-thinking process and acquire the skills to do so. 2.3.1.3 Okkeun Lee

Figure 16 Okkeun Lee Status = 1st year Stanford Ph.D. graduate student Email = [email protected] Phone = +1 650-785-8965

I am from South Korea. My background is in mechanical engineering. Upon my graduation, I first worked as a mechanical engineer at Samsung Electronics for three years. After few years of engineering experience, I changed my role from an engineer to a product designer. I worked for about three and a half years as an industrial designer at Samsung Electronics and designed many products, as well as winning international design prizes such as IDEA and Good Design Award. I finished my master course in UK, Innovation Design Engineering (co-operated by Imperial College and RCA). After graduation, I worked as a senior designer and researcher at Native design in London for 2 years. At that time, I joined a team for Autonomous Vehicle project working with Ford. P a g e | 11

I definitely think that ME310 is a good chance for multi-disciplinary, global students and designers. I think this is quite useful to extend and upgrade my design skills. I am thrilled to work with people from different backgrounds and cultures. I have a lot of experience both of engineering and design. Therefore, I'm sincerely not afraid to work with the students from the different areas. I could contribute to harmony the team members, having different backgrounds. Besides, I did a lot of work with prototyping both of design and engineering process and I worked at the companies using 3D tools like Solidworks, UG-NX, Creo 2.3.1.4 Tin Jing Jie

Figure 17 Tin Jing Jie Status = 1st year Stanford M.E. graduate student Email = [email protected] / [email protected] Phone = +1 650-441-4755

Hi, I'm Jing Jie but just call me JJ! I'm a first year MSME student, and am aiming to specialize in robotics. I'm from Singapore, and I did my undergraduate studies at Imperial College London. I am currently on a government scholarship and am attached to the Public Utilities Board of Singapore, which is Singapore's National Water Agency and manages the collection, production, distribution and reclamation of water in Singapore. I am interested in exploring how robotics can be used to expand Singapore's water supply, and I play volleyball and basketball in my free time. From ME310, I hope to understand how out-of-the-box thinking is achieved, and gain knowledge of systematic design and problem-solving methodologies that are widely used in industry. I aim to apply such knowledge to Singapore's water industry, where it is imperative to explore and find new approaches of increasing our water supply. I have embarked on a number of P a g e | 12

designs, manufacture and test projects in my undergraduate studies, which include scooters, hand-held power tools, a pseudo mine detecting robot and a haptic input force assistance system for Operating Theatre Lights. Hence, I can contribute some experience in mechanical and mechatronic design, some proficiency in coding (MATLAB, C) , some project management experience, and some manufacturing skills (mills, lathes etc.). I see myself contributing towards Singapore's water security by designing new water treatment processes and technologies.

2.3.2 Aalto University

2.3.2.1 Dai Jiang

Figure 18 Dai Jiang Status = 1st year Aalto Business graduate student Email = [email protected] Phone = +358 417189595

I am Dai from China. I studied in Global Business in China and continue studying in Management and International Business in Finland. I did research on marketing when I was undergraduate and I had a paper about packaging label influencing customer preferences to be published. I used to be a volunteer in Thailand for 2 months, teaching local primary school students English. Almost no one there could speak English, so most of the time we use body language to communicate with each other. The culture differences interested me a lot and made me start thinking about the connection between people. I am taking this course because I want to keep myself busy. I am kind of a passive person who would get immersed in a comfortable zone, and I really hope P a g e | 13 to push myself out and far away from it. Also, I hope I could do some real things, instead of doing readings and writing essays all the time, which is usually what business students do during school. I did researches about marketing during my bachelor, studying on how languages on packaging labels influence customer preferences. I hope I could bring some thoughts and ideas about users to our team. I majored in Global Business when I was undergraduate. And now keep studying in it as a graduate student. My major was so broad and abstract that I still don't know which way to go. I hope I could relate my job to things I interest in. I like to spend time with kids and animals, so I hope I could find jobs that related to them. I want to find a way to develop animal shelters and special schools differently, in which way they can make profits instead of waiting for others to donate them. 2.3.2.2 Samuel Moy

Figure 19 Samuel Moy Status: ME graduate student Contact: samuel.moy@aalto.fi I am a master’s student in ME at Aalto University specializing in Product Development. I studied mechanical engineering as my bachelor’s at the University of Colorado. My previous work involves project management and product design. I enjoy working in groups and being involved in innovative projects. I enjoy sports and music. I like to play the drums and also making things whenever I get the chance. P a g e | 14

2.3.2.3 Timo Mayer

Figure 20 Timo Mayer Status: ME graduate student Contact: timo.mayer@aalto.fi

I am a Master’s degree student in Mechanical Engineering at Aalto University in Finland. I am from Nuremberg, Germany and grew up in Sydney, Australia. I did my Bachelor of Engineering in the latter and worked in the former for an internship for 3 months. I very much enjoy my sport and have been playing football and tennis most of my life, and about 1.5 years ago I started climbing. Other interests of mine include music, books, and video game. 2.3.2.4 Mika Julin

Figure 21 Mika Julin Status: Masters Student- Product Development Email: [email protected] Phone: +358 40 7084567

P a g e | 15

I am Mika Julin from Aalto University Finland, currently I'm doing my masters studies majoring product development in department of Mechanical Engineering. I did my bachelor to Material Science and Engineering majoring Functional Materials. As a former athlete of tennis, I'm still very much into sports. I like to cycling, cross country skiing, playing tennis and working in gym. Outside sports I like to play guitar, cooking and playing board games with friends My biggest expectations towards ME310 are getting to put all the knowledge I've learned in previous product and service development projects together while learning design thinking mindset. I would like to also meet new enthusiastic people to work with. Due to previous experience in product and service development projects, I feel that I can bring know-how to multiple phases of the project, e.g. defining the design space and prototyping. In 5 years I hope I'd be a product developer in an interesting field making people's everyday life better. 2.3.2.5 Nina Saarikoski

Figure 22 Nina Saarikoski Status: PhD, Department of Industrial Management Contact: aino.saarikoski@aalto.

Half-French, half-Finnish, born in Oslo, Norway and from Paris. My area of expertise is strategic management of technology with a particular focus on the cleantech industry and Goto-Market strategies. I also hold a Licentiate Degree (Post Graduate Degree) in Political Science from the Department of Political Science, University of Helsinki and a Master’s Degree in Anthropology from Sorbonne University- Paris V, - both of which prove to be very helpful in understanding the so-called wicked problems generated by climate change. Proud alumni of Design Factory’s PDP course. Among other things, I like to cook traditional French patisseries and watch HBO P a g e | 16

3 Design Development

3.1 ME 310 Kick-Off

After being assigned to Xylem we started working on possible directions that we could take. First, we looked into Xylem as a company and explored ways in which innovation could help the company. Next we carried out need finding to uncover needs in our design space. During this time we researched examples of biomimicry for inspiration. The team looked at mangroves, baleen whale filters etc. We also did benchmark on products that used biomimicry.

3.2 Fall Quarter

3.2.1 Desalination

The team looked into desalination because of the vast amount of salt water in the world and the inhabitants living close it it. The team decided to take on desalination in low pressure chambers. The idea also stemmed from the experiment done with a syringe where water can boil at room temperature. The team decided to build a large-scale syringe and test the question, “can an average adult lift a low-pressure chamber with water to desalinate sea water?” The image shows a person lifting the plunger of the syringe past a designated marker (marked as tape). This indicated that the user, as calculated, would need to pull with approximately 80 kg of force. The tests involved filling the syringe with water and see whether a person could lift the plunger. The result was that a person could lift the plunger which was approximately 80 kg of force.

Figure 23 Desalination Prototype P a g e | 17

One crucial learning is that a person is capable of lifting 80kg, however it is not a comfortable experience. Additionally, not much of the water was evaporated, and therefore desalinated, which meant that a person worked too hard to gather a small quantity of desalinated water. This was useful to look into other areas of desalination and water treatment since this process was highly energy-intensive and also not a comfortable user experience.

3.2.2 Underground Irrigation

The inspiration for this prototype came from the Texas horned lizard which draws moisture from any surface by capillary action and gets it to its mouth. Can we get the water straight to the root of the plant and prevent waste from evaporation? The underground irrigation system is a modified drip irrigation system designed to reduce the amount of water lost to evaporation and maximize the water reaching the roots of the plant. The pipes carrying the water are buried below the soil. The capillary action in the soil brings the water up to the higher roots and gravity takes it to the lower ends of the roots. Since the water system is underground, the pressure needed can be created using water head in the water storage container. The pressure can also be controlled by controlling the water level in the storage container. The prototype as shown in figure below was built to compare the traditional drip irrigation system to the new underground system. Holes were made in a plastic container to insert the two tubes. The tube for the drip irrigation goes over the ground level while the underground tube was bent upwards to make an inverted U like structure and put at a height below the ground. The water sources used were paper cups with holes at the bottom for tubes. The water flow is controlled by clothes-pins that pinch the heat shrink fitted between a joint in pipes. The end of the pipes are shut off once the air bubbles are removed.

Figure 24 Irrigation Prototype P a g e | 18

3.2.3 Xylem Based Water Filtration

During the fall quarter, the Stanford and Aalto team decided to study bio-inspired methods of filtration. Aalto University explored a promising study which used white pine xylem filters to filter dirty water, where the filters were able to produce high quality, crystal clear water. However, as the xylem filter was gravity fed, the obtained flow rates of filtered water in the conducted study were very low and the xylem filter alone would not be able to meet the water needs of a large user community. Hence, the Alto team explored potential measures to increase the filtration speed of such filters, and developed the idea of using conventional syringes to increase the pressure through the xylem filter. In the Alto team’s experiment, a piece of pine wood with bark removed was chosen as the xylem filter and fit into a plastic tube. The Team tested the filtration rate with and without pressure exerted by the syringe piston. Without pressure, the flow rate was 1 drop per minute. With pressure the flow rate of water was 15 drops per minute.

Figure 25 Xylem Based Filtration Prototype

3.2.4 Oyster Based Water Filtration

The Stanford University team discovered that adult oysters could filter approximately 5 liters of water per hour through a filter feeding mechanism, which allows the oyster to produce 120 liters of clean water a day. By drawing water over cilia (dense hair-like structures) in its gills, the oyster is able to trap particles and bacteria in the mucus membrane of its gills to produce clean water. The Stanford team then designed a filtration system inspired by oysters. A piece of cloth with fibers was layered with mucus and water was poured over it. This method of cross filtration was subsequently improved upon by constantly recirculating the same water multiple times through the same filter. In addition, P a g e | 19

both filtration methods involved using a pumping mechanism to either increase pressure or recirculate the water.

Figure 26 Oyster Based Filtration Prototype

3.3 Winter Quarter

In Winter Quarter 2019, both teams explored solution spaces tangential to those explored in the Autumn Term (water filtration). Need finding conducted by the Stanford team revealed that up to 31% of schools worldwide lack access to clean drinking water, which adversely affects the health and education experience of some 570 million children. Crucially, rural schools in developing countries tend to have lower quality water facilities as compared to schools in urban settings. Benchmarking also revealed that commonly used water filters in developing countries such as gravity + bio sand and ceramic filters could not deliver high flow rates of purified water, and often could not provide a sufficient water supply for large communities. Hence, the Stanford team aimed to meet the clean drinking water needs of rural school children by developing a low cost method of capturing and storing the mechanical energy dissipated by footfall as the user walks, where user generated pressurized air would be used to increase the flow rate of contaminated water through a filtration system to obtain a large quantity of clean drinking water. P a g e | 20

3.3.1 Microplastics Detection

The Aalto team found that microplastics were causing extensive damage to the marine ecosystem. In addition, microplastics were also found to be prevalent in bottled drinking water which was regularly consumed by people, where microplastics levels are expected to grow in the future. Hence, the Aalto team strongly believed that the ingestion of large quantities of microplastics would pose a severe threat to human health in the future, and explored potential solutions throughout the Winter Quarter. In Dark Horse I, the Alto team created a small box in which users could observe tiny plastic particles in water, and found that users who could observe such pieces were less willing to drink such water. In the Funktional and Functional prototyping phase, the Aalto team designed a microplastic detection device which used spectroscopy to identify plastic particles and met with limited success, as the system could not reliably detect plastic pieces which were smaller than 1mm in small concentrations.

Figure 27 Microplastics Detector

P a g e | 21

3.3.2 Dark Horse 1: Human Powered Personal Water Filtration

Figure 28 Working Principle of Human Powered Water filtration In Dark Horse I, the Stanford Team designed a wearable air compression system which could be attached to the user’s foot, and a centralized water storage and filtration system. The system was able to achieve flow rates of up to 80 times faster with 30 user steps as compared to gravity fed methods, which demonstrated that compressed air could potentially achieve significantly improved flow rates.

Figure 29 Pumping System

Figure 30 Filtration System P a g e | 22

3.3.3 Dark Horse 2: Pipe Leak Detection and Repair Robot

Figure 31 Working principle of Pipe Repair and detection Robot The Stanford Team explored the development of an autonomous water pipe fixing robot to reduce the amount of purified water lost through pipe leaks. However, the prototype met limited success in maneuvering in cast iron pipe interiors with magnetic wheels while critical system functions such as crack detection and repair were not explored, and this line of exploration was abandoned.

Figure 32 Circuitry for the prototype

Figure 33 Pipe Repair Robot Structure P a g e | 23

3.3.4 Funktional Prototype

The team built on the key learnings of the Dark Horse I concept for the Funktional system deliverable to produce a floor-based air compression system. Test results were promising which showed that 1000 user steps delivered 750ml of treated water.

Figure 34 Floor Based Air Cushion

Figure 35 Filtration System P a g e | 24

Figure 36 Entire Prototype

3.3.5 Functional Prototype

The team focused on fine-tuning both the shoe and floor-based systems to improve their efficiencies. Test results indicated large efficiency improvements, where the shoe-based system could produce 200ml of treated water after 25 user steps, while the floor-based system produce 20ml of treated water per step. Next, the Functional system prototype was improved upon to produce the final prototype of the 2019 Winter Quarter, where the improved shoe-based system was able to obtain 580ml of treated water with 25 steps, while the improved floor-based system was able to obtain 90ml of treated water per step. Therefore, the prototypes of Winter Quarter 2019 by the Stanford team demonstrate a strong potential for meeting the clean drinking water needs of a large community through the capture, storage and utilization of compressed air to accelerate the flow rate of contaminated water through conventional filters, and will continue to be pursued and refined in Spring Quarter 2019. P a g e | 25

Figure 37 Personal Foot pump

Figure 38 Air Cushion

Figure 39 Common Filtration Module P a g e | 26

3.4 Spring Break

During the Spring Break, the Stanford Team flew to Finland to visit our international team at Finland. The main goal of the Spring Break meeting was for both teams to converge on a single user and a final product design concept. On the first meeting day on Monday (3/25/19), both teams embarked on a day long brainstorming session to produce new concept ideas for the Spring Term. This was conducted as the Aalto team felt that there were insufficient product ideas from both teams, and therefore a greater number of ideas would have to be generated to increase the chances of obtaining a good final idea. Aside from the foot-based and floor-based water filtration systems which the Stanford Team had presented, two new ideas were produced through this brainstorming session. The first new idea was a water pricing scheme presented by Aalto University, where users would purchase water for usage in much larger volumes of 100L instead of paying for water per liter. The goal of this idea was to present users with a prefixed amount of water to use per month instead of paying for their water bills at the end of the month, such that users would be inclined to use water conservatively within their budget and consequently use less water over a month. However, members from both teams noted that this idea was more of a policy to craft rather than a product to design, and it was quite unlikely that users would be keen to inconvenience themselves by taking on this water use policy. Therefore, this idea was rejected. The second new idea involved the retrofitting of existing water dispensing systems with visual displays which would depict the environmental impact of low, medium and high-water usage. For example, it was envisioned that the usage of low volumes of water from a shower would translate to positive images of a healthy environment, while the usage of large volumes of water would translate to negative images of environmental pollution to the user. Hopefully, such images would nudge users to use less water to avoid negative imagery to conserve the environment. However, members from both teams felt that such it would be hard to craft specific imagery that would universally appeal to / repel users, where the crafting of such imagery did not play to the team’s strengths where team members were predominantly mechanical engineers. Hence, the second idea was rejected as well. On the second meeting day, the choice for the final product design concept was narrowed down to foot-based and floor-based human powered water filtration systems previously proposed by the Stanford Team. The foot-based system was ultimately rejected due to the fact that an individual system would be required per child, which would increase production and maintenance costs. There were also large safety concerns with regards to the mounting of an air cylinder with up to 60psi of pressurized air on a child’s foot, where damage to the air cylinder could compromise the child’s safety. Hence, the floor-based system was selected as the final product design concept due to a greater ease of maintenance for a centralized system, as well as the fact that the floor-based system was able to generate much higher pressures and flow rates than the floor-based system. P a g e | 27

3.5 Spring Quarter

3.5.1 Need finding

In the Spring Quarter, the team focused on meeting the drinking water needs of rural populations who lack access to a stable electrical supply to treat contaminated waters. According to the WHO, 844 million people lack a basic drinking-water service, including 159 million people who are dependent on contaminated surface water sources to meet their daily drinking water needs (WHO, 2019). Contaminated surface waters often contain pathogens which transmit waterborne diseases such as diarrhea, cholera, dysentery, typhoid, and polio that cause 502 000 diarrheal deaths each year (WHO, 2019). Furthermore, heavy metal concentrations in rural surface waters in developing countries often exceed WHO health-based drinking water guidelines. For example, waters in Chhattisgarh, a state in Central India, were found to have Lead concentrations which were 10 times above WHO guidelines (Tiwaria, et al., 2015) as shown in Figure, while (Fernández-Luqueño, et al., 2013) reported that Arsenic concentrations in drinking water in India was approximately 11 times higher than WHO guidelines on average. (Tiwaria, et al., 2015) also notes that rural populations are disproportionally affected by such contaminated surface waters as they mainly depend on such waters to meet their daily water needs, and often do not have access to electricity to power conventional filtration systems to treat such contaminated waters.

Figure 40 Heavy metals in Chhattisgarh in India P a g e | 28

3.5.2 Choice of User

In particular, rural school children in developing countries form the most vulnerable population subset who are continuously exposed to sediments, pathogens and heavy metals on a daily basis. 31% of all schools worldwide lack access to safe water (Charity Global, 2019), which results in 272 million schools days missed every year (UNICEF, 2010) and has an adverse impact on the educational experience of such children. In addition, children are particularly susceptible to heavy metals such as Lead as they absorb up to 8 times more Lead than adults which leads to severe cognitive and motor deficits (Abelsohn & Sanborn, 2010). Hence, there is a strong need to develop a low-cost, sustainable and easily maintainable product which can remove sediments, pathogens and heavy metals such as lead from contaminated surface waters to ensure an adequate, clean drinking-water supply for such rural children. Keeping this is mind the team fixed on Ravi Kumar The user is a 7th grade student in a rural school on the outskirts of Gurgaon, India. His school does not have access to a piped clean water supply, and instead draws water from a nearby contaminated freshwater source. Ravi frequently falls sick and has diarrhea due to regular consumption of untreated water. “The water does not taste good and it also stinks, however since everyone in the school drinks the same water, I also drink the same”

P a g e | 29

3.5.3 Benchmarking Technologies

3.5.3.1 Gravity and Bio-sand Filters

Figure 41 Gravity and Bio Sand filters Many filtration systems have been developed to treat contaminated surface waters in rural regions, most notable of which are gravity + bio-sand filters. Such filters have several advantages, such as being low cost ($70) (Project, 2015) and do not require an external energy source; gravitational force is instead harnessed to force contaminated water through the filtration layers and reduce pathogen count in the treated water. However, such systems also suffer from several disadvantages. For gravity + bio-sand filters, the biolayer is the key component of the filter which removes pathogens. Without the biolayer, the system is only able to remove 30- 70% of the pathogens through mechanical trapping, where an ideal biolayer would be able to remove up to 99% of pathogens from the system. However, the biolayer takes up to 30 days to fully form and treated water requires additional disinfection in this time frame, which makes the biotreatment process of such filters highly inefficient. As seen in Figure 4, the treatment efficiency of the gravity + bio-sand filters fluctuate significantly as the bio-layer develops, which indicates that the quality of treated water also fluctuates greatly. Furthermore, slower flow rates are ideal for such filters to allow more time for pathogens to be absorbed by the bio- sand layer, which prevents the system from generating large flow rates. Maintenance is also highly complex and inconvenient for the user, where lengthy pause periods of up to 48 hours are also required to allow time for microorganisms in the biolayer to consumer microorganisms in the water. In this period, the user would not be able to obtain clean water from the gravity + bio-sand filter. However, extended pause periods beyond 48 hours run the risk of the micro-organisms P a g e | 30 consuming all the nutrients and pathogens and eventually dying off, and therefore maintenance for such systems must be carefully timed as well (CAWST, 2009). Therefore, gravity + bio-sand filters suffer from low flow rates, complex maintenance, variable treated water quality and are also unable to remove heavy metals from contaminated waters.

Figure 42 Treatment efficieny of the product as the bio layer develops 3.5.3.2 Ceramic filters

Figure 43 Ceramic filters Ceramic Filters also suffer from several key disadvantages. There is variable filter quality control for locally produced filters in rural areas; such filters also easily break over time and require spare parts. Ceramic filters also produce low P a g e | 31 flow rates of 1-3L/hr. for non-turbid waters, and filters must also be maintained and cleaned regularly, especially after filtering turbid waters. Similar to gravity + bio- sand filters, ceramic filters are also not able to remove heavy metals from the contaminated water. 3.5.3.3 Katadyn Expedition Filter The Katadyn expedition is a ceramic filter system which uses human power to filter water. It filters out about 4 liters of water per min. It can filter water for large groups of people and can filter water that is very dirty. The biggest downside is that it is very expensive at $1,499.

Figure 44 Katadyn Filter 3.5.3.4 IDEO Aquaduct The Aquaduct is a pedal powered concept vehicle which transports, filters and stores water for rural populations in developing countries, and allows a person to simultaneously transport and filter up to 8 liters of water per instance (Etherington, 2008). As the rider pedals, a pump attached to the pedal crank draws water from a large tank, through a carbon filter, to a smaller clean tank which is removable and closed for contamination-free home storage and use. Although the Aquaduct is able to make distant water sources more accessible while providing filtration capabilities, the system is also prohibitively expensive for rural users who lack significant finances, and also requires extensive maintenance due to the large number of moving parts in the bicycle. The system is also able to only treat and store 8 liters of drinking water per instance, which prevents the product from meeting the drinking water needs of a large number of people. In addition, the Aquaduct does not remove heavy metals as well from contaminated water. P a g e | 32

Figure 45 Aquaduct 3.5.3.5 PlanetWater’s Aqua Tower The AquaTower developed by Planet Water Foundation is a long-lasting product (lifespan of up to 10 years) that is able to produce 10,000L of clean water per day to serve the drinking water and sanitation needs of 1,000 people. While this product can meet the drinking water needs of a large community, the entire system costs approximately $11,000, is unable to remove heavy metals and also requires quarterly maintenance by professionals who carry out more extensive maintenance of filter systems. Furthermore, communities are also required to have access to a water well and an electric pump such that contaminated water can be pumped to the large water holding tank situated at the top of the AquaTower.

Figure 46 PlanetWater's AquaTower P a g e | 33

Therefore, benchmarking results indicate that there are the common shortfalls in existing filtration systems:

• Low flow rates • Unable to remove heavy metals • Highly complex maintenance procedures • Potentially expensive • Not compact

3.6 Our Design Vision

Our design vision is to design a method of harnessing the mechanical energy dissipated by user footfall to power a low cost, easily maintainable filtration system which would be able to remove sediments, pathogens and heavy metals. This captured mechanical energy would then be used to rapidly increase the flow rate of contaminated water through the implemented filter components

3.7 Algae Concept Development

Initially the idea was to make an algae filter to take the heavy metals out as the water is passed through it. However, we realized soon that the immobilization of algae in the filter was a complicated chemical process and cannot be achieved easily. This also increases contact time required to adsorb the heavy metals. So, we decided to treat the water with algae by mixing a fixed quantity of it in the dirty water tank. This however raised new concerns. First was the desorption of heavy metals back into the water from the algae. To clear this issue, we contacted an author of a well cited paper. He confirmed that after an equilibrium is established, there is no desorption of the heavy metals. Second was that we had to take the algae out of the water in the dirty water tank. To do this, first we designed a sediment filter. However, it reduced flow rate and also increased maintenance. So we decided to use chitosan and flocculate the algae to get it out of the water. This is described in the design specification section in detail P a g e | 34

Figure 47 Chlorella Vulgaris

3.8 Algae Cultivation

Since algae is a fast-growing sustainable resource our initial concept was to have the villagers grow the algae themselves. To simulate this we bought algae culture and started growing algae in a tub while monitoring its progress. We tried varying different parameters. We managed to grow some algae but we decided that it wasn't feasible for the villagers to grow the algae themselves. We finalized on a distribution system where algae would be produced in nearby cities and shipped to these villages on a three-monthly basis. This would allow them to use the algae and not worry about the algae crop failing.

3.9 Initial Design

The initial concept for the system was inspired from a water cooler. The dirty water tank was kept at the top. The water flows from this tank, into an intermediate tank which is connected to the foot pump. Air pressure is built up in this tank and water is forced out of the filters due to this pressure. To control the flow of water into this intermediate tank, a float valve was designed. The water was collected in a clean water tank from which it was dispensed into the container of choice. P a g e | 35

Figure 48 Layout of Initial Design

Figure 49 Initial Design concept

3.9.1 Part X

Our part X was the float valve since it was crucial to the functioning of the system, and the part most likely to fail. The float valve provides two level control. This allows the flow to start and stop when the tank is empty and full respectively. The float valve was P a g e | 36

made by 3d printing. The force required to keep the valve shut was calculated and a sufficiently strong magnet was selected and embedded in both the top and bottom portions of the valve seat.

Figure 50 Part X

Figure 51 Part X concept

3.10 Design Changes

After the part X was completed, the design was heavily revised. The team realised that using air to build pressure was resulting in a design that was maintenance heavy due to leakage concerns. Also we found from our collective experience that the traditional water dispensers with the water tank at the top were top heavy; which was both a safety concern and an ergonomic nightmare (the user had to lift the tank over the dispenser to install it). So, we decided instead to pump water through the filters directly with a water foot pump. This eliminated the need for the float valve and all the associated complexities of the P a g e | 37 initial design. Also, we designed the system in such a way that the user will not need to lift the water jug over the top and easily slide it and connect it to the system.

P a g e | 38

4 Design Requirements

4.1 Functional Requirements

Table 1 Functional Requirements

REQUIREMENT METRIC RATIONALE PUMPING SYSTEM The foot pump should be able to The foot pump must be To be robust enough for 15- support the weight of the 95th able to support a load of year-old children to step on percentile of 15-year-old students 84kg the foot pump, including a safety factor of 1.2 The system needs to withstand Able to bear 2 million Robust system for a long continuous stepping and loading sinusoidal loading cycles system lifespan by students. over 5 years with maximum force amplitude of 500N before the onset of high cycle fatigue failure The system needs to provide 2 liters a day per student / To provide enough clean enough clean drinking water for a 100 liters to be produced water to meet the drinking class of 50 15-year-old students per day for the system water of students The foot pump needs to provide The foot pump should be To provide clean water at a sufficient amount of water per able to pump at least 30ml quicker flow rate step per step The foot pump should generate Pressure of 25 psi should To ensure efficient pumping sufficient pressure in the system be generated The pipes need to be small to A 6mm diameter pipe will To ensure efficient pumping ensure adequate suction pressure be suck water from the 20L tank FILTRATION SYSTEM The system needs to remove Remove at least 95% of To provide safe drinking significant quantities of heavy heavy metals (Pb, Cr, Mn) water metals in contaminated water The filter needs to prevent lead- It needs to remove 90% of To ensure a clean, long absorbed algae from entering the the algae in the tank lasting system system P a g e | 39

The system needs to remove The system should be able To provide safe drinking significant amounts of pathogens, to reduce pathogen and water chemicals and suspended solids suspended solids levels to acceptable levels as advised by US EPA standards The filter needs to remove The system needs to To provide potable drinking unpleasant odor and taste reduce the foul taste and water smell to 1% of its original intensity Filter to have long life expectancy Minimum working life of To reduce the overall cost of 5 years before the product replacement Filter needs to be able to handle Backwash every 7 days To improve the life frequent backwash expectancy of the system The filters need to have a low Operating pressure of 15 To ensure efficient pumping operating pressure psi The filters need to have a low Backwashing pressure of To ensure easy and efficient backwashing pressure 20 psi cleaning of the filter requirement ALGAE SYSTEM The algae needs to be circulated An air circulation pump of To prevent algae from in the water 1Lpm will be included in settling down the system The algae extraction system An extraction method To ensure heavy metal needs to be precise and accurate such as a cup to extract 1 extraction from water gram per 20L of water The algae growth needs 1 tablespoon of fertilizer To ensure sufficient nutrients assistance for 50L of water should be are present in the tank for the added on a bi weekly algae to grow basis The algae growth needs A circulating mechanism To ensure that the algae can assistance with the help of a solar breathe and circulate around powered air pump will the tank aerate the water. Flow rate of 2 Lpm would be sufficient BACKWASHING SYSTEM P a g e | 40

The backwashing system needs to 2 liters of clean water to To prevent extra water loss use less water to clean all the backwash the filter filters The backwashing system needs to A pressure of at least 20 To effectively backwash the have a low operating pressure in psi to backwash the filters system the water dispenser The system needs to collect waste A tank of 6cm x 8cm x To prevent spillage of from backwashing 40cm to collect water harmful contaminated water

4.2 Functional Constraints

Table 2 Functional Constraints

CONSTRAINT RATIONALE The system maintenance does not require To ensure that an adult with no or less technical experience or education technical background can conduct maintenance in less than 30 minutes The system needs to motivate children to step To provide the correct amount of clean on the foot pump drinking water a person needs the entire day The system needs to be easy to use without To remove the need of education to use the education system The algae system needs to be easy to maintain To ensure that an adult (e.g. a teacher in the school) does not spend a lot of time monitoring the algae system The system needs to be safe To ensure that the children get clean drinking water

4.3 Functional Opportunities

Table 3 Functional Opportunities

OPPORTUNITIES RATIONALE The system can include a motivational message An indicator showing the difference in the to use the system or a way to educate children clean and contaminated drinking water about the need of clean drinking water The system can include an option to notify the Besides the reduction in flow rate, a visual teacher when backwashing is needed representation can be added to the system

P a g e | 41

4.4 Functional Assumptions

Table 4 Functional Assumptions

ASSUMPTION RATIONALE The filtration system can handle all type of dirty To ensure universal application of the water product The system will not have users who are very To assume a fixed height (of children) while tall designing the system The algae system will be considered as an To ensure that the user includes the algae important aspect by the user and will not be stages in the filtration system to ensure neglected efficient filtration of heavy metals from water The user preserves and protects the algae bath To ensure that the user does not render the algae useless by destroying the cell walls or killing the algae The system can be used by people in first world To ensure global distribution countries as well

4.5 Physical Requirements

Table 5 Physical Requirements

REQUIREMENTS METRIC RATIONALE The system needs to be light The system needs to weigh To make the system highly weight less than 20kg (without the portable 20L water tank) The faucet/outlet needs to be The height of the faucet To be easy for young student at reachable for the 10th should be no more than to reach percentile of 10-year-old 70cm above ground level Indian students The system should be Maximum water dispenser Easy to transport to remote, modular, portable and system footprint to be a rural areas, and to occupy less compact 50cm x 50cm base and space in schools height of 100cm The algae growing system A growing tank of 100cm x To ensure adequate algae is needs to be compact and in 100cm x 50 cm will be present for heavy metal sunlight sufficient for growing filtration algae P a g e | 42

The system needs to be easy Total Connection time Ease in handling to connect to the water tank should not exceed more than 2 minutes

4.6 Physical Constraints

Table 6 Physical Constraints

CONSTRAINT RATIONALE The system needs to be durable The system will need to handle operation by children who may be rough with usage The system needs to be bottom heavy To ensure the system does not tip over with a nudge The algae system needs to handle all weather To ensure the algae does not die conditions

4.7 Physical Opportunities

Table 7 Physical Opportunities

OPPORTUNITIES RATIONALE The system can be made quite attractive in To ensure people in first world countries exterior design can also purchase this system for their home The system can be made out of injection The overall structure will be one piece molding if the demand for the product is high which is more stable and durable

P a g e | 43

5 Design Specifications

5.1 System Description

Our envisioned system is a low cost, modular and highly compact system that allows rural users to remove heavy metals, pathogens and sediments from contaminated water to produce safe, odorless drinking water. This is achieved without an external energy source, where a human powered foot pump forces contaminated water through mechanical filters in the system to achieve a high flow rate of clean drinking water.

Figure 52 Our Final Product The flow chart for our system’s operation is shown in Figure below which consists of 2 separate phases. The first phase is a contaminated water pre-treatment phase with microalgae cells (Chlorella Vulgaris) which absorb heavy metals into its cell walls. Next, a bio-flocculent (Chitosan) is added which clumps algae cells into large flocs. By virtue of their larger weight, such large flocs would proceed to settle at the bottom of the dirty water tank, thus preventing lead-filled algae from entering the filtration system. After the first phase, heavy metal count in the contaminated water is greatly reduced by virtue of P a g e | 44 biosorption of heavy metals by algae. In the second phase, the user proceeds to connect the dirty water tank to the main filtration system. By stepping on a water pump, the user forces the dirty water through a sediment filter, hollow fiber membrane and Granular Activated Carbon (GAC) filter which removes large particles, pathogens and taste and odor from the water respectively. Hence, clean water which is devoid of heavy metals, pathogens and odor is produced for our user. P a g e | 45

Figure 53 Process of Operation P a g e | 46

5.2 System Overview

5.2.1 Bio-Adsorption of Heavy Metals

5.2.1.1 Reduction of Lead Concentration in contaminated waters through the usage of Chlorella Vulgaris Following Xylem’s prompt of using inspiration from nature to design the next generation of water treatment technologies, the team explored the usage of the microalgae species chlorella vulgaris in the removal of heavy metals such as Lead. Although several removal methods such as reverse osmosis have been proposed and implemented to address environmental pollution by heavy metals, the biosorption of such pollutants by naturally inspired sources such as microalgae has considerable advantages, and have been extensively studied due to their natural origin, overall cost-effective ratio, and effectiveness against a broad pollutant range by being able to absorb many different types of heavy metals (Bilal, et al., 2018). For our product’s rural users, the usage of algae presents a low cost, highly effective, easy to implement and hence sustainable method of removing heavy metals from contaminated water sources

Figure 54 Ion Exchange in Algae Heavy metal uptake by microalgae consists of two mechanisms, a dominant, rapid biosorption reaction and a slower, metabolism‐dependent bioaccumulation of heavy metals into the algae cell. In the biosorption of heavy metals, positively charged heavy metals replace H+ ions by a process of ion exchange which allow heavy metal ions to bind to the functional groups on the algae cell wall as shown in Figure (Bilal, et al., 2018). In bioaccumulation, heavy metals are absorbed into the algae cell through internal diffusion. Chlorella Vulgaris was chosen as the microalgae species for our filtration system. This is because this species demonstrates a strong capacity for absorbing large quantities of heavy metals without dying for many different types of heavy metals. The maximum heavy metal P a g e | 47 adsorption capabilities per gram of Chlorella Vulgaris for a wide range of heavy metal species is presented in Table 1 (Inthorna, et al., 2002).

Table 8 Heavy Metal Adsorption by Algae Heavy Metal Maximum Adsorption Capacity / mg/g Lead (Pb) 127.0 Cadmium (Cd) 76.0 Mercury (Hg) 18.0 Copper (Cu) 89.0 Nickel (Ni) 59.7 Zinc (Zn) 6.60 Assuming a Lead concentration of 2000ppb, (Inthorna, et al., 2002) reports that a Chlorella Vulgaris biomass concentration of 1g per liter of contaminated water would deliver a lead removal rate of 88% in 20-30 minutes. Crucially, the team wished to test if a lower biomass concentration of algae could potentially deliver a similar Lead removal rate for a much lower concentration of Lead (100ppb). If such a Lead removal rate could be achieved with lower biomass concentrations, this would bring Lead levels to 12ppb which is within EPA limits of 15ppb, and would also reduce the amount of algae in the dirty water tank and hence reduce backwashing requirements for the sediment and micro filters to make the system more maintainable. The team was optimistic that such a lower biomass concentration could achieve the above stated goals, where the usage of qmax, C and Kb values reported by (Inthorna, et al., 2002) and the Langmuir equation given in Equation 1 gave theoretical adsorption values of 4.02mg of Lead per gram of algae. 100ppb of Lead translates to 0.1mg of Lead per liter of water, while 0.35g of algae would theoretically be able to remove 1.407mg of Lead per liter of water. Hence the theoretical Lead adsorption capacity of Chlorella Vulgaris was much higher than the amount of Lead present, and the team was optimistic that lower biomass concentrations could produce favorable results. 퐶 푞 = 푞푚푎푥 ∗ (퐾푏 + 퐶)

푤ℎ푒푟푒 푞 = ℎ푒푎푣푦 푚푒푡푎푙 푎푑푠표푟푏푒푑 푡표 푡ℎ푒 푠표푙𝑖푑 푝ℎ푎푠푒

푞푚푎푥 = 푚푎푥𝑖푚푢푚 푎푑푠표푟푝푡𝑖표푛 푐푎푝푎푐𝑖푡푦 퐾푏 = 퐵𝑖푛푑𝑖푛푔 푐표푛푠푡푎푛푡 퐶 = 푒푞푢𝑖푙𝑖푏푟𝑖푢푚 푐표푛푐푒푛푡푟푎푡𝑖표푛 표푓 ℎ푒푎푣푦 푚푒푡푎푙 𝑖푛 푡ℎ푒 푠표푙푢푡𝑖표푛 5.2.1.2 Usage of Chitosan as a bio-flocculant for algae With the application of an algae biomass concentration of 1g/L, the Stanford Team faced a new design challenge, which was the need to extract large amounts of algae from the dirty water tank. Since the envisioned system was expected to use 100g of algae to P a g e | 48 purify 100L of contaminated water per day, this would have resulted in a significant amount of algae passing through the sediment and micro filter membranes. This would dramatically increase filter maintenance and backwash requirements, while significantly lowering the flow rate of clean water through the system due to the rapid clogging of the filters, which would impose an unsustainably high maintenance cost on our rural users. To overcome this problem, the Stanford Team explored the usage of Chitosan in 1% Acetic solution as a bio-flocculent for Chlorella Vulgaris. Chitosan powder was found to require 5 times less mass (0.25g/L) than traditional flocculants such as Alum Sulfate to flocculate 90% of algae biomass in 10 minutes (Zhu, et al., 2018). Hence, Chitosan was determined to be a low-cost, rapid method of removing large amounts of algae from the dirty water tank. During flocculation, positively charged Chitosan attracts and neutralizes the negative charge of the microalgae cells, thus forming larger algae particles which settle to the bottom of the dirty water tank by virtue of their much higher weight. Three jars depicting live algae, chitosan solution and flocculated algae is shown in Figure below. As seen in the flocculated algae jar in Figure 9, flocculated algae settles to the bottom of the jar to leave a large column of clear water that has minimal algae and heavy metal ions remaining in the system. This prevents algae from being absorbed into the filtration system which minimizes maintenance and backwashing cost. This concludes the pre-processing phase of contaminated water, where Chlorella Vulgaris has been used to extract heavy metals and Chitosan has been used to prevent algae from entering the main filtration system

Figure 55 Algae, Chitosan and Flocculated Algae P a g e | 49

5.2.2 Mechanical and Chemical Filtration

5.2.2.1 Removal of large sediments through a 0.5-micron radial sediment filter. To prevent any remaining Lead-filled algae particles from entering the main filtration system, the Stanford Team designed a custom radial sediment filter as shown in Figure. The custom sediment filter was placed in the dirty water tank, and served as the inlet for contaminated water into the main filtration system. The filter was created by wrapping 5 layers of 0.5-micron Polyester felt cloth around a cylindrical wire mesh, which was then forced into two caps with an outlet nozzle placed at one end.

Figure 56 0.5-micron filter A schematic of the operating mechanism of the sediment filter is given in Figure 11, which was placed in the dirty water tank. As the user steps on the foot pedal in the main filtration system, a vacuum is created. Hence, water is sucked in radially through the 0.5-micron cloth into the wire mesh. This water which is now devoid of large sediments then exits via the outlet nozzle into the main filtration system. Layout of filters and tanks

Figure 57 Working of 0.5-micron filter P a g e | 50

As the size of Chlorella Vulgaris cells ranges from 3μm to 10μm (Milo, 1985), a cloth pore size of 0.5μm would be able to remove an extremely large percentage of remaining algae in the dirty water tank while preventing large sediments from entering the main filtration system. By designing a custom radial sediment filter which was smaller and less bulky as compared to commercially available sediment filters, the Stanford Team could place the custom filter in the dirty water tank to minimize the amount of algae entering the main filtration system. By creating a radial sediment filter, this maximized the filter medium surface area which in turn minimizes backwashing requirements of the system, while increasing the flow rate of water through the filter surface. 5.2.2.2 Removal of pathogens through a 0.1-micron hollow fiber membrane filter Next, water enters a 0.1-micron hollow fiber membrane filter after passing through the sediment filter. Hollow fiber membranes offer a simple, effective method of purifying water by passing contaminated water through a non-chemical, physical barrier to effectively remove microbiological contaminants from water. Schematics of the working principle of hollow fiber membranes are given in Figures 13 and 14. Although Figure 13 shows the feed-stream on the inside of the hollow fiber, the feed stream is more commonly applied on the outer surface of the fiber so that the membrane is pressurized against the porous support (McKeen, 2012) . Since the pore size of the hollow fiber is 0.1 microns, this prevents harmful bacteria and pathogens which range in size from 1 to 10 microns in length and 0.2 to 1 micron in width (WQA, 2019) from passing through the membrane. Instead, only water molecules are allowed to pass through the membrane, such that the permeate as shown in Figure no longer contains pathogens. By bundling individual hollow fiber membranes together, a hollow fiber filtration system is created as shown in Figure which allows for the treatment of larger volumes of contaminated water, and also increases the generated flow rate of clean water through the system. Furthermore, the small pore size also traps any remaining algae in the filtration system, and ensures that the user does not accidentally ingest Lead-filled algae. P a g e | 51

Figure 58 Hollow Fiber Membrane Structure

Figure 59 Cross Section of Hollow Fiber membrane The MINI Sawyer as shown in Figure was used as the hollow fiber membrane filter in the Stanford Team’s filtration system. The MINI Sawyer was chosen due to its small compact size and low weight, which would allow the Stanford Team to design a highly compact housing module for the filtration systems. Furthermore, the Sawyer filter was rated to remove 99.99% of bacteria and protozoa, which would meet the filtration requirements of removing a significant amount of pathogens from the water. Crucially, the MINI Sawyer has an extremely low cost of $20 and a long filter life where it is rated to filter up to P a g e | 52

100,000 gallons (Sawyer, 2019), which would mean that the microfiltration system would not have to be frequently replaced. This reduces maintenance and system costs for our end users. These properties make the MINI Sawyer an ideal microfiltration system for the Stanford Team’s product.

Figure 60 Hollow fiber Membrane 5.2.2.3 Removal of odor and taste with a Granular Activated Carbon Filter Water enters a GAC filter after passing through the MINI Sawyer microfiltration system. GAC filters are able to remove certain chemicals such as hydrogen Sulphide and Chlorine which contribute to bad taste and odor in water. GAC is made from raw organic materials such as coconut shells or coal that are high in carbon, which absorb chemicals present in water to remove these chemicals from the water stream (DOH, 2019). As the presence of algae in the dirty water container introduces an “earthy” taste which makes drinking water taste like dirt (WaterLogic, 2019), and the presence of other organic compounds in untreated surface water also introduces bad taste into drinking water, a GAC filter is necessary to make water pleasant tasting such that rural users will be inclined to use the Stanford Team’s product. A T33 Inline Coconut Grade Activated Carbon Membrane Filter as shown in Figure was used as the GAC filter for the Stanford Team’s filtration system. This particular GAC filter was chosen due to its low cost of $7.49 and its long lifespan of 2 years, which reduces maintenance and product cost for our rural users P a g e | 53

Figure 61 Granular Activated Carbon Filter

5.2.3 Human Powered Pumping System

The human powered pumping system is a key component of the Stanford Team’s filtration system. As our rural users do not have access to an electrical supply, they do not have an external, constant energy source to power a filtration system, and must rely on either gravity feed or human powered methods to accelerate the flow rate of contaminated water through conventional filter systems. Gravity-fed methods are infeasible due to the large height and space requirements needed to generate a good hydrostatic pressure to force water through the filter systems, where a height of 10m is required to generate 1bar of additional pressure. Hence, human powered methods were deemed to be the most promising solution to drive water through the filtration system due to their sustainability and lack of cost the user, and was actively explored by the Stanford Team. As seen in Figure 7, a user operated water foot pump was used to harness human energy to power the filtration system. The Whale baby foot operated pump as seen in Figure 17 was chosen as the foot pump for the filtration system due to its compact size and high water pressure output.

Figure 62 Whale Baby Foot pump P a g e | 54

Figure 63 Cross Section of Foot Pedal

By stepping on the foot pump, the water stream after the foot pump is forced forward. This creates a vacuum in the foot pump, which then proceeds to draw in water from the main dirty tank. This simple operation method allows the user to simultaneously draw in water from the dirty water tank while forcing water through the filtration systems at high pressure, which produces a good flow rate P a g e | 55

Figure 64 Piping Diagram P a g e | 56

Figure 65 Normal operation P a g e | 57

5.2.4 Filter Backwash

Under normal operating principles, the sediment and micro filters trap particles on the filter surface. With continuous filter operation, trapped particles gradually build up on the surface of the filter media, which clogs the pores of the filter and reduces the flow rate of water through the filtration system. Hence regular preventive maintenance in the form of filter backwash is necessary so that the filter media can continue to be used while maintaining a good flow rate for rural users. Backwashing is carried out by reversing the water flow through the filter media, where the water flow from the opposite direction clears the filter medium of collected particles (LLC, 2019). The ejected particles would then have to be directed to a backwash collection tank for storage for future removal by the users. Crucially, a large proportion of water filtration projects aimed at providing poor rural populations with clean filtered water fail because of complex maintenance procedures, where the inability or lack of interest in rural populations in executing such complex procedures regularly results in the eventual discontinued use of such systems by rural populations (Wessel, 2019). Therefore, the designed backwash mechanism for this product must be highly intuitive, easy to execute and hassle free, such that there is no disincentive for rural users to not conduct regular filter backwash. A schematic of the designed backwash system is shown in Figure. In Step 1, the user simply turns two knobs from “normal” to “backwash” mode, where the modes in which the user is supposed to turn the tap to are engraved on the wood panels on the product. Once the taps have been turned to the backwash position, the user fills a syringe with clean water set aside for backwashing and connects it to the backwash inlet. Thereafter, the user simply pushes against the syringe pistol until the clean water in the syringe is emptied, and backwashed water is simply collected in a coke cylinder for later removal by the user. After backwashing is completed when 2 syringes of clean water have been used for backwash, both knobs are simply returned to normal position to allow normal filter operation. Given that backwashing only requires the turning of two knobs and the connection of a syringe to the backwash input, this presents a straightforward, hassle-free backwashing system for users. P a g e | 58

Figure 66 Backwash Operation P a g e | 59

5.3 Final Product Testing and Performance

For final product testing and performance analysis, the Stanford Team focused on acquiring Lead testing data with a lower biomass concentration, and analyzing sediment filter performance and the amount of clean water generated with each user step, while the Aalto team focused on user testing for a larger version of the final product. To perform Lead testing with a lower biomass concentration, the Stanford Team enlisted the help of our Xylem corporate sponsor, Jessica Moyer, to conduct Lead testing with a biomass concentration of 0.35g/L in lead concentrations of 100ppb. Lead Testing was conducted with Inductively Coupled Plasma – Optical Emission Spectrometry (ICP- OES) and Atomic Absorption Spectrometer (AAS), where the goals of the experiment were as follows. 1. To establish if an algae biomass concentration of 0.35g/L could bring 0.1mg/L lead concentration waters to EPA standards for lead in drinking water 2. To establish the contact time required to bring 0.35g/L lead concentration waters to EPA standards for lead in drinking water an algae biomass concentration of 0.35g/L. Upon the addition of live algae to 100ppb Lead concentration solution, samples were extracted every 10 minutes for Lead testing to evaluate the impact of different contact times on the Lead removal capability of Chlorella Vulgaris. Test results indicated that there as an immediate (<5 minutes) drop in Lead concentration levels to 27ppb from initial levels of 100ppb. However, it was observed that in the course of the Lead experiment that the concentration of Lead in the system actually increased to 47 ppb by the 15-minute mark and remained constant till the end of the 60- minute experiment. The most plausible explanation for this was that the initial adsorption of 73ppb of lead into the algae became toxic to the species, which resulted in the algae subsequently desorbing some of the lead back into the filtrate. Both experimental methods (ICP-OES and AAS) reported similar trends in the Lead removal capability of Chlorella Vulgaris for 0.35g/L biomass concentration in 60 minutes. Crucially, it should be noted that while the final heavy metal concentration of 47ppb was above the stringent EPA standards of 15ppb, such heavy metal concentrations actually met drinking water standards in developing countries such as India, which specifies lead concentration of 50ppb as safe for human consumption (Times, 2008). Since our product is targeted at rural areas in such developing countries, the Lead testing experiment indicates that the lowered biomass concentration of algae successfully meets the required drinking water standards in such countries. Furthermore, experimental results indicate that biosorption of heavy metals indeed proceeds at a rapid pace, and a safe drinking water standard is achieved in a short span of 15 minutes which is highly convenient for the user. However, since the final P a g e | 60 concentration of 47ppb is just below the 50ppb standard, the Stanford Team chose to pursue the usage of a biomass concentration of 1g/L in the final product to ensure even higher levels of Lead removal. Next, the Stanford Team analyzed the performance of the sediment filter to determine if it could successfully remove a large amount of algae from algae water. This would ensure that if any remaining algae remained suspended in the system after flocculation, the sediment filter would prevent the remaining algae from entering the piping network and filters of the system. Testing results as shown in Figure indicate that the sediment filter works to a large extent, where green algae water in the bottom cup becomes significantly clearer after passing through the sediment filter as seen in the top cup. The remaining color in the top cup is attributed to aqueous nitrates and phosphates in the waters as the algae was extracted from a culture self-grown by the Stanford Team, which gives the water a slightly brown color as observed. Hence, the custom designed radial sediment filter is able to remove large amounts of remaining algae in the dirty water tank while providing a large flow rate and low maintenance / backwash requirements due to the large surface area of the radial filter

Figure 67 Removal of Algae through filter Next, a clean water flow rate analysis was conducted on the final product. Testing results are captured in Table 2 below. With a flow rate of 40 ml/step with all filtration systems in place, 25 steps are required per children to obtain 1L of clean water per day

Table 9 Flow through filtration stages

Filtration System Flow Rate ml / step Sediment Filter + Micro filter + GAC 40 Micro Filter + GAC 45

P a g e | 61

5.4 User Testing

Testing of the prototype was first carried out during hardware bazaar, where different people tried it. Their suggestions were noted. A primary concern was that the height of the water dispensing spout was too low. Although meant for children, the spout height was found to be too low. The users liked the concept of the foot pump and the fact that the action of pressing the foot- pump caused clean water to flow out resulting in a visible and tangible feedback. The angle of the foot pump was found to be too high for some adults which would be an even bigger issue for children. The issues were rectified by first raising the water spout and then making the foot pump panels longer thus reducing the angle. The Aalto team carries out user testing with children and their findings were positive. The children loved playing on the foot pump and enjoyed the water flowing in the system. They also found creative ways of using the foot pump. A key insight obtained was that the system could be made fun for children to use. This could be a possible design space to explore further.

Figure 68 User Testing conducted by Aalto University

5.5 Business Model

We propose a variation of ‘the razor and blades’ business model and the partnership with the local EDTECH ecosystem and in particular Bangalore-based 'Think & Learn' startup operating Byju’s learning app platform [1], -high growth, profitable, one of the world's successful EdTech startup currently looking to accelerate its growth within India and reach the majority of Indian schoolchildren - which would be fit as well within Xylem's Watermark school and community projects and education. This will entail a partnership between Xylem, a local water utility and Byju P a g e | 62 for the creation of an ‘all in one--all in a box’ ALGAE EDU-BOX, which would contain a package of educational content (tailored to communities with no electricity at this stage) and learning experiments around clean water and algae as well as the bio- filtration itself for the classrooms (which would provide instructions, the algae, and the chitosan for the flocculation). This revenue model has a so-called 'premium business model' where a yearly paid subscription is required for most of the educational content (in this case science experiments revolving around growing algae and water purification processes) and the filtration system product would be included in a subscription. For example, a yearly $50 payment for the educational content for each school covers the costs of the manufacturing for the algae filtration system. This initiative could also pave the way at a later stage for a community-managed 'algae production cooperative' in communities, run by women, which each community growing and harvesting cost-effectively the algae needed to filtrate its water resources. The water utility would be responsible for the training of the cooperative workers as well as the early setups of the maintenance process for the filtration system. The water utility would also recoup its investment in the treatment of the algae sludge and in the recycling of the algae for production of biofuels for example and of the heavy metals captured by the algae during the filtration process.

5.6 Future Plan

Xylem could continue to make this a final product which could then be distributed to villages across India and the world. However, a few changes would make the entire system more ideal to use. The algae system while very effective can be a tedious job. An immobilized Algae filter would ease the process. In this method, a cartridge made out of Algae will be inserted in a filter and water would flow through this filter. While coming in touch with this Algae, heavy metals would be adsorbed by the Algae. This would reduce the overall consumption of Algae per Liter of water and would make for a hassle-free process. Another way this entire system could be improved is the use of multiple strains of bacteria. While we have Chlorella Vulgaris that is particularly effective in removing lead, there are other strains that can remove other heavy metals more effectively. The product would also need a visual method of detecting the overall performance of all the filters and the purity of the water. This would better educate our user.

P a g e | 63

6 Project Management

6.1 Distributed Team Management

Upon converging upon a fixed user and a final product design concept at the end of the Winter Break, we distributed the workload for each team. The Stanford Team was assigned to develop an algae-based filtration system and the structure of the final product, while the Aalto Team was assigned the design of the mechanical filtration system of the system. The Gantt Chart for the Stanford Team for the Spring Quarter is shown in the figure.

6.2 Communication:

Following every SGM, the Stanford Team was responsible for taking the initiative to communicate and send completed documents to the corporate contacts of Xylem Inc. A weekly international meeting was held at 8am every Thursday between the Xylem corporate contacts, Stanford University and Aalto University teams to bring each party up to speed about the progress of each party’s deliverable during the Spring break. In these meetings, all teams discussed the latest research findings, learnings and prototype testing during the course of the Spring Term. Such calls were also useful in realigning each team to the agreed upon objectives, and to allow each team to understand the various challenges that each team faced in producing weekly deliverables. Many videos were also communicated between each team, such that each could obtain a more detailed understanding of each team’s prototype.

6.3 Role Distribution between Team Members

Roles were assigned to Stanford Team members as follows: • Adit Desai and Fay Colah: In charge of ideating and finalizing system mechanical design • Fay Colah: Team mom and in charge of product assembly • Okkeun Lee: In charge of designing the final prototype and manufacturing • Tin Jing Jie: Algae and Chitosan researcher

P a g e | 64

Figure 69 Gantt chart for Spring Quarter P a g e | 65

7 Team Reflections

7.1 Adit Desai

ME 310 has been a great journey from start to finish. It has been the highlight of my time here at Stanford. I enjoyed exploring the entire design space, finally settling on a direction and making it real. I learnt a lot about design methodology, product development and not surprisingly water filtration and algae. Every new prototype was exciting and fun to make. However, the things that i will take away from ME 310 will be all the interactions with my team and the ME310 community. As a team we started off unorganized but slowly gained traction once roles were clearly defined. In this process every member found new things that they were good at. I learnt a lot from my team including technical and real-world skills. Although communicating with the international team was not easy, we started making it work in the spring quarter. As a team we were always finishing 5 minutes before deadlines which was stressful but usually our most productive time. At the end it felt like I wasn't working but just spending time with friends.

7.2 Fay Nicole Colah

ME 310 has occupied a major chunk of my first year at Stanford. I have had a roller coaster of a ride for these past 9 months. During the start of my term with Xylem, we had a slow start, trying to work with our international team members and trying to brainstorm for ideas. As the fall quarter went by, I sat down with worry, wondering how would I meet the requirements of this course. That’s the best part of ME310, no matter which background or depth you come from, ME310 finds a way to make you invest your soul in it. It teaches you to learn new skills or improve the ones you have. Every day you learn something new at the ME310 loft, that’s for sure. Winter and Spring Quarter changed my team into a family with whom I spent 60 hours a week. At times we reached a wall, screamed at each other and then continued working again to reach our goal for the week. ME 310 can bring out the best and the worst in you. But it’s an experience that is 100% necessary when you study at Stanford. Working with Adit, JJ and Okkeun has been an amazing experience. We have bonded together as a group, our skillsets complementing each other’s brilliantly. I did not expect ME310 to change my life outside of academia directly. I believe it is a good change though. It gets you ready for the hard-working life of a startup or a company or research. I am truly going to miss ME310, I have not yet finished this course and I already know that my life is going to be pretty empty without it. Take ME310, dance with ambiguity, pull your hair out at that statement, work insane hours and appreciate the experience.

7.3 Okkeun Lee

With completing the last quarter in ME310, I was able to benefit from a variety of new experiences from this class, as well as new insight of design thinking and problem- P a g e | 66

solving process. The contents of the class in spring quarter especially prototyping and group thinking are useful to develop my skills to approach a complex project of design and engineering. It was a great adventure, but we have overcome so many huddles with my team members including the guys in Aalto. The variety of strengths and abilities which they have showed in this project was great to complete and make this success outcome. The biggest hurdle in this project for me was time management due to the short period of project time. However, the support of teaching team and structure of this class is useful to organize time management. I am seriously happy to work with them and my team members. I do appreciate all teaching teams’ help and my team members’ efforts.

7.4 Tin Jing Jie

Coming into ME310 in the Winter Quarter, I was extremely excited about the prospect of learning design methodologies from the teaching team and believed that design skills would be something that was “taught” to me. I definitely did not expect from the onset that my greatest takeaways from this course would come from sleepless nights trying to get prototypes to work, or the beating of our heads against the wall as we tried to produce new, feasible ideas after previous ones had proved unsuccessful. ME310 was truly an adventure, where there were many twists and turns and dead ends before a feasible solution was finally stumbled upon. I am truly glad to have been assigned to work in the Xylem team, our skill sets were highly complementary and we gelled well together, allowing us to push each other all the way to the finish line to deliver a final feasible product. If there’s one thing I learned, there is always light at the end of the tunnel, no matter how long and dark the tunnel is as we strive towards our goal solution.

7.5 Dai Jiang

I have a very different experience in this course than my other courses as a business student. Instead of reading and writing essays, I did need finding and benchmarking and made some prototypes together with my teammates. I learned a lot about iterative process, which need us to repeat to do, check, and do again. Also, because the project we are working on have been so open and broad, I learned a lot about identifying problems. It was difficult but inspiring to neither narrow our project too much nor lost our direction to continue. It was also interesting for me to work with teammates from different background and different cultures, although we met disagreement and conflicts sometimes. I learned a lot about teamwork during the process of reaching agreements. It was definitely an unforgettable experience to work with teammates for ME310. I liked the way how we ideate and brainstorming and I learned a lot about product development processes. it was amazing that we create many things from nothing just based on our brief. Although there were still many things that could have been better, such as our team dynamic etc. I really appreciated the whole eight months with ME310. P a g e | 67

7.6 Samuel Moy

This academic year during ME310 was filled with many experiences. I like the content of the course where a student learns to do need finding, benchmarking, how do make prototypes, and to test with users. Also, the fact that the student does different types of prototypes is a good approach to product development. I also liked the connections I made with students from other universities and with the corporate sponsor. I also liked that I went through a rigorous product development program and I could use my learnings in the future. I wished, however, that some things behind the scenes were done better in terms of the teaching teams. For instance, the documentation rubrics are different between teaching teams of other universities, but it is asked that we have the same documentation. There was also no push to test with users from the Stanford teaching team (it seemed so), whereas in Aalto this is one of the main focuses. Also, there was no structure in how to assign group roles and to deal with team dynamics. It was all up to the students, and that is ok but it's a job in its own. I encourage teaching teams to teach how to assign roles or work well in a group. I hope there can be some more organization in the course so that the valuable content can be appreciated. Thanks.

7.7 Timo Mayer

Overall, during ME310, I went from knowing very little about water outside the obligatory fluid dynamics bachelor engineering education to becoming very familiar with many of the problems and current solutions regarding water. Furthermore, I also became much more aware of what was in my water. In terms of the course itself, I learned a lot regarding product development and about the correct process which I hope to profit from greatly in the future if/when I work for a company which heavily emphasizes innovation. I also, however, learnt about the difficulties of work and how hard it can be to manage a group of people whose opinions diverge greatly. Hopefully, this is also a way in which the course prepared me for my future career.

7.8 Mika Julin

The reason I signed up for ME310 was that I’ve done a few product development project courses in the past, but I really wanted to combine all the learnings from those courses as well as get to know the design thinking method more. The brief from Xylem was super open and quite often it felt that open brief doesn’t fully fit to the process of ME310. Also, some misalignment with the challenges made the global co-operation harder and created redundant work. The openness of the brief remained as a challenge for pretty much until the final concept was chosen. Despite many challenges, I’m glad we ended to tackle a problem that has a huge impact globally and that we completed a viable proof-of-concept prototype. P a g e | 68

Possibility to work and network in international team with students from Stanford was one of the major takeaways from the course.

7.9 Nina Saarikoski

ME310 was a very interesting challenge to take on. With a multidisciplinary and international team composed of mechanical engineers, business, management and design graduates team work was intensive, sometimes strenuous but always rewarding in the end. I liked quite a lot Xylem's brief which gave us the opportunity to use biomimicry to solve some of the most pressing challenges in the developing world and potentially save lives in the end. Xylem's constant and highly precise technical feedback when we were elaborating prototypes was also a high point of this course as was the very positive reception for our bio- filtration solution during EXPE. All in all, a year to remember!! P a g e | 69

8 Bibliography

• Abelsohn, A. R. & Sanborn, M., 2010. Lead and children. Can Fam Physician, 56(6), p. 531–535. • Bilal, M. et al., 2018. Biosorption: An Interplay between Marine Algae and Potentially Toxic Elements—A Review. Marine Drugs, 16(65), pp. 1-16. • CAWST, 2009. Biosand Filter Manual: Design, Construction, Installation, Operation and Maintenance, Alberta: CAWST. • Charity Global, I., 2019. Clean water means more kids in school. [Online] • Available at: https://www.charitywater.org/global-water-crisis/education • DOH, 2019. Water Treatment Using Carbon Filters: GAC Filter Information. [Online] • Available at: https://www.health.state.mn.us/communities/environment/hazardous/topics/gac.html#GA C • Etherington, R., 2008. Dezeen: Aquaduct by IDEO. [Online] • Available at: https://www.dezeen.com/2008/03/11/aquaduct-by-ideo/ • Fernández-Luqueño, F., López-Valdez, F., Gamero-Melo, P. & Suárez, S. L., 2013. Heavy metal pollution in drinking water - a global risk for human health: A review. African Journal of Environmental Science and Technology, 7(7), pp. 567-584. • Inthorna, D., Sidtitoona, N., Silapanuntakul, S. & Incharoensakdi, A., 2002. Sorption of mercury, cadmium and lead by microalgae. ScienceAsia, 28(1), pp. 253-261. • LLC, 2019. How Backwashing Filters Work. [Online] • Available at: https://www.purewaterproducts.com/articles/how-backwashing-filters-work • McKeen, L. W., 2012. Markets and Applications for Films, Containers, and Membranes. In: Permeability Properties of Plastics and Elastomers. s.l.:Elsevier, pp. 59-75. • Milo, R., 1985. BIONUMB3R5: The database of useful biological numbers. [Online] • Available at: https://bionumbers.hms.harvard.edu/bionumber.aspx?id=101481&ver=7 • Project, T. W., 2015. How Biosand Water Filtration Systems Work. [Online] • Available at: https://thewaterproject.org/biosand_water_filtration • Sawyer, 2019. MINI WATER FILTRATION SYSTEM. [Online] P a g e | 70

• Available at: https://sawyer.com/products/mini-filter/ • Times, T. E., 2008. Lead content in water in India far above BIS specifications. [Online] • Available at: https://economictimes.indiatimes.com/lead-content-in-water-in-india-far- above-bis-specifications/articleshow/2889515.cms • Tiwaria, M. K., Bajpaia, S., U.K.Dewangana & Tamrakarb, R. K., 2015. Assessment of heavy metal concentrations in surface water sources in an industrial region of central India. Karbala International Journal of Modern Science, 1(1), pp. 9-14. • UNICEF, 2010. Lack of safe water and sanitation in schools affects children’s learning – and their lives. [Online] • Available at: https://www.unicef.org/media/media_53234.html • WaterLogic, 2019. Why does my water taste like dirt?. [Online] • Available at: https://www.waterlogic.com/en-us/resources/water-problems/why-does-my- water-taste-like-dirt/ • Wessel, L., 2019. The human factor in clean water. [Online] • Available at: https://www.knowablemagazine.org/article/health-disease/2019/human- factor-clean-water • WHO, 2019. Key Facts of Drinking Water. [Online] • Available at: https://www.who.int/news-room/fact-sheets/detail/drinking-water • WQA, 2019. Bacteria & Virus Issues. [Online] • Available at: https://www.wqa.org/learn-about-water/common-contaminants/bacteria- viruses • Zhu, L., Li, Z. & Hiltunen, E., 2018. Microalgae Chlorella vulgaris biomass harvesting by natural flocculant: effects on biomass sedimentation, spent medium recycling and lipid extraction. Biotechnol Biofuels, 11(183), pp. 1-10.

APPENDIX A- CAD Images

APPENDIX B- EXPE Presentation

APPENDIX C- EXPE Brochure

APPENDIX D- EXPE Posters

APPENDIX E- Part X Handout

APPENDIX F- Initial Manufacturing Plan