Automated Planting and Harvesting System Design for Aquaponics Farm Implementation of Automation in Aquaponics System

THESIS - BACHELOR'S DEGREE PROGRAMME TECHNOLOGY, COMMUNICATION AND TRANSPORT

AUTOMATED PLANTING AND HARVESTING SYSTEM DESIGN FOR AQUAPONICS FARM IMPLEMENTATION OF AUTOMATION IN AQUAPONICS SYSTEM

A u t h o r / s : Manahari Paudel

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SAVONIA UNIVERSITY OF APPLIED SCIENCES THESIS Abstract

Field of Study Technology, Communication and Transport Degree Programme Degree Programme in Mechanical Engineering Author(s) Manahari Paudel Title of Thesis Automated Planting and Harvesting System Design for Aquaponics Farm Date 10/12/2020 Pages/Appendices 42 Supervisor(s) Mikko Nissinen Client Organisation /Partners One Farm Nepal Abstract

This was a design project for an automated aquaponics farm. This project was commissioned by One Farm Nepal. This is an upgrade project as the company is operating the aquaponics farm with manpower. The main aim of this project was to automatize the aquaponic system. Designing the system utilizing most of the available space was the main motto of this project.

The theory of this thesis was based on the triangulation method which includes a qualitative method, quantitative method, and lean model. Delphi method was used to get the accurate result. In soilless farming and automated system it was referred to different sources including Dr James Rakocy from University of the Virgin Islands (UVI).

A complete model of an aquaponics farm was designed. The combination of automated aquaculture and soilless farming with the measurement of water parameters completes this system. For the process automation, the use of robotic arm and motors for different purpose like lifting, picking, and monitoring has helped the automated system.

The design of the project is workings perfectly yet, there is some part in the system where improvement can be done. The robotic track can be extended so that the robotic arm can cover the fish tank for fish harvesting. The water parameter can be controlled by the use of robot.

Keywords Aquaponics system, automated aquaponics farm, handsfree farm, robotic arm

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CONTENTS

1 BACKGROUND INFORMATION OF THE RESEARCH ...... 5

1.1 Motivation ...... 5

1.2 Previous Research ...... 5

1.3 Research Problem ...... 5

2 OBJECTIVE OF RESEARCH ...... 7

2.1 Objectives ...... 7

2.2 Research question ...... 7

2.3 Hypotheses ...... 7

2.4 Scope ...... 7

3 RESEARCH METHODS ...... 9

3.1 Qualitative methods ...... 9

3.1.1 Material Selection ...... 10

3.2 Quantitative methods ...... 10

3.3 Lean Model ...... 11

4 SOILLESS FARMING ...... 12

4.1 Hydroponics ...... 12

4.1.1 Media bed ...... 13

4.1.2 Flood and Drain ...... 13

4.1.3 Nutrient Film Technique (NFT) ...... 14

4.1.4 Deep Flow Technique (DFT) ...... 14

4.2 Recirculating Aquaculture System ...... 15

5 AUTOMATED SYSTEM DESIGN ...... 18

5.1 Grow light ...... 18

5.2 Machine vision ...... 19

5.3 Robotic arm ...... 19

5.3.1 Serial robot ...... 20

5.3.2 Parallel robot ...... 20

5.3.3 Attribute of serial and parallel robots ...... 21

5.4 Process parameters ...... 22

6 DESIGNING AN AUTOMATED AQUAPONICS FARM ...... 23

6.1 Fish Tank ...... 24 4 (42)

6.2 Mechanical filter ...... 25

6.3 Gripper attachment ...... 27

6.3.1 Hand gripper ...... 28

6.3.2 Seeding nozzle ...... 28

6.3.3 Claw gripper ...... 29

6.4 Plumbing ...... 30

6.5 Conveyer belt stand ...... 31

6.6 Hydraulics table ...... 33

6.7 Pump and motors ...... 34

6.8 Frame and roller ...... 36

6.9 Design Summary...... 37

7 CONCLUSION ...... 39

REFERENCES ...... 41

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1 BACKGROUND INFORMATION OF THE RESEARCH

Farming is one of the most important activities that must be carried out for the survival of human being. In traditional farming, soil is the main media for crops to be grown. Due to repeated plowing and weeding, the crops which are grown in the soil require more efforts and need extra care. Over a time, inherent method of farming has changed significantly. In modern days of farming, there are ways of growing crops or rearing animals. Many chemicals used in soil-based farming to meet the ever-growing demand of food supply are harmful to our health. Sustainable farming is the only way to provide food for the over-growing population. Aquaponics system (AS) is a soilless sustainable farming technique. At around 1000AD the Aztec Indians used to grow plants on top of the lake with the help of rafts (ACS, 2020).

1.1 Motivation

During the visit to Nepal, different companies for the thesis topic were visited. The author had a clear picture about the field of research. Research on agriculture automation motivated the author. Among a few firms, it was decided to collaborate with “One Farm Nepal Pvt. Ltd” which is specialized in soilless farming. A weeklong meeting on the farm gave an opportunity to know the detail inside of aquaponics farming technique. AS resembles the process automation. As the elements in an aquaponics system are connected via water line/bodies, it is easier to dilute or concentrate any element as per the measured process parameter value.

1.2 Previous Research

There have been many researches going on regarding the AS. A professor from the University of Virgin Islands Dr James Rakocy and his team has carried out significant research on ideal AS (UVI, 2020). Automated system has already been introduced from monitoring the water in the recirculating system to the growth of plants and fish. Soilless farming being one of the most interesting topics among the farmers and agriculture automation research community.

Likewise, monitoring of pH level, temperature and dissolved oxygen are already made automated with some sensor and scales. In many cases, integrated robots are used to make the system work for itself which helps in making the system require less manpower. Research which was done in Al-Ruya Bilingual School (RBS) shows how an automated system or use of robotic helps in monitoring the parameters of the aquaponics system. (RBS, 2017).

1.3 Research Problem

Due to the ever-growing population, the demand for food supply is growing exponentially higher every year. In addition to this, farmland is being destroyed due to global warming, construction of housing and recreational area. If we only rely on the conventional method of farming, this will lead to a severe shortage in the food supply. To address this problem productivity or production density per square 6 (42)

foot must be increased. Soil based farming requires periodic weeding, plowing and nutrient amend- ment. It is a power demanding task even for a machine. There is a need for a simple, efficient, light equipment friendly farming technique. This thesis aims to implement process automation in aquaponics for saving growing space, productivity, and man-hours.

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2 OBJECTIVE OF RESEARCH

2.1 Objectives

Attributes of the Aquaponics system are familiar with process automation, so the idea was to operate aquaponics system without any manpower from planting to harvesting. The purpose of this project was to design a complete aquaponics farm which runs without any interruption considering all its parameters. The robotic arm will be used in the process of monitoring, lifting, and harvesting the plants. Every part of the design is equally important for the automated system like deep water culture bed, fish tank and plumbing.

2.2 Research question

1. How is the system operated at the initial stage? 2. Why is UR3 robot used instead of another robotic arm? 3. Why is it necessary to implement automation in Aquaponics System? 4. How do fish tank, filter and tanks relate to the entire system? 5. How is the system affected if the water quality is not maintained?

2.3 Hypotheses

Automated aquaponics system eradicates the needs of manpower in the system. The space(footprint) required for three different units is reduced to one as all three come under the same roof. In one square foot, the plants and fish are grown. The aquaculture system and soil-based farming takes a lot of space because it cannot be done at the same place, so it requires separate space for both farming and sapling of the seeds.

By incorporating automated aquaponics farming we can have a handsfree system and save 25% of the land than by doing traditional farming. In this way, we can utilize maximum space to grow fish and plants.

2.4 Scope

For a given variety of seeds limiting factors for crops production are water and nutrient availability. In an AS both limiting factors are readily available as plants in AS grows on nutrient rich water. In AS lighter media can be used to support the root system enabling to develop multi-level farming. The proposed design of AS system is designed in such a way that, under the same square foot coverage three levels of production can be achieved.

Aquaponics farming can be done in a majority of places. Simply rooftop or a balcony can be a place where the system can be setup or any unused spaces. The scope of aquaponics farming has increased 8 (42)

because aquaculture farming and soil less farming or growing of the plants can be done in the same place without requiring two different places.

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3 RESEARCH METHODS

Among various methods of information processing, methodological triangulation is used to analyse the whole process. Triangulation method involves the use of qualitative and quantitative methods to study the process. It is based on the literature, survey, interview, calculation, prototyping, etc.

Calculation

Literature Prototyping Figure 1: Triangulation method

3.1 Qualitative methods

There are several qualitative research methods which are proven scientifically. Among them, literature based qualitative method was used. As the system was designed based on the transfer of technology, well known literature published by an renowned author was used. This was because there is already a lot of work done by different researchers and well reviewed documents are available on automation of aquaponics. This research aimed at combining these systems to work together and act as a functional unit. Therefore, each topic was carefully studied, and the end-result was bound by those publications.

However, to analyse qualitatively the feasibility of the project, Delphi method was used. It is a well known research tool used by the researchers of the master and PhD level. This method is fruitful when the target is to calculate the range of understanding of question, answer, and opportunity (Pareoline, 2007). Figure 2 shows the three round Delphi process.

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Experience

Literature Research Research Research Delphi Delphi R1

Review Question Design Sample R1 Pilot Survey &

Analysis

Pilot Studies

Delphi R2 Delphi R2 Survey Design & Analysis

Research documentation, Delphi R3 Delphi R3 Verification & Design Survey & Analysis Generalization Figure 2: Three round Delphi process

The research begins with the making of a small prototype of the system. The author will be involved in the project untill the prototype is built, finalizing all the parameters of the system. Only after the success of test, a large scale system will be built.

3.1.1 Material Selection

Material selection for this system was very important as majority of the system is in contact with the water. The selection of materials might be tricky for example iron as a material for the fish tank might result in rusting which will eventually damage the entire system by poisoning the fish. Normal standard construction materials can be used for the system apart from those which are in direct contact with water like grow bed, fish tank and water tank.

The selection of materials for the tanks was made between two materials namely fibre glass and stainless steel. Fibre glass is easy to install and costs less whereas stainless steel tank costs more and is difficult to install because of its weight. The durability of fibre glass is only about 20 years whereas stainless steel lasts long.

Fibre glass has less life compared with stainless steel, but it is cheaper. The entire system will last long if the material is stainless steel because if fibre glass is used in the system, it needs to be changed after a certain time and this might cost more during the long run of the system.

3.2 Quantitative methods

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Quantitative research methods narrow down the research topic. It provides a fundamental connection between observation and mathematical expression (Lisa M, 2008). Quantitative research method provides information in the form of number, percentage, array, matrix, graph, pie charts, etc. The quantitative analysis deals with the calculation of fish stocking density, flow rate in different tanks, nutrient demand for specific plant, pump sizing for air and water flow, etc. Data used in quantitative analysis is propriatory property of One Farm Nepal Pvt. Ltd. therefore, it is not presented in this thesis.

3.3 Lean Model

The concept of the lean model is that it is a functional unit of least size. Before working on the main project, a miniature project is made, which can be of any size. The project is an exact replica of the main project. It works as the main project with all the framework, tank system and with conveyer system. The only difference between the main project and this miniature project is that it does not have robotic arm other all functions are the same. The advantage of having a miniature project is that the project can be explained to the visitors without touring the entire farm as the small replica covers everything the main project has and is easier to understand.

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4 SOILLESS FARMING

4.1 Hydroponics

Hydroponics system is the process of producing plant and crops in soilless condition and also known as soilless culture system. The required supply of water and minerals are run through nutrient solutions. Hydroponics system can be divided into open and closed system. In an open system the unused nutrient solution is not recycled whereas in the closed system it is recycled. (Simon et al 2019, 78.)

Figure 3: left Open Cycle System, right Closed Cycle system (Simon et al. 2019, 78)

Hydroponics is a soilless farming system where crops are grown in water by supplying the required nutrients in a dissolved solution. In this process plants are grown 20% faster than in the soil and it takes less space. Being completely in water helps this system to be as compact as possible because the root of the crop does not take much space to get the nutrients. Since the system is closed loop there is no waste of water and only enough water that requires to grow them are consumed by plants. (Steve, 2006.)

Hydroponics has a different system where plants are to be grown from backyard to large scale system. In a hydroponic system the widely used substrate system for flood and drain is media bed substrate system.

Deep water culture (DWC) and nutrient film technique (NFT) are other subsystems of hydroponics. DWC hydroponic subsystem can be found in small sizes like in private homes and in profit-oriented firm. Comparing with other two hydroponic subsystem NFT has balance relation with water, energy, and less labor with large plant cultivation areas. It is not true that all the plants which are to be grown in the NFT system are good, so it is almost mandatory to find favorable plants for each hydroponic subsystem. (Thespruce, 2020.)

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4.1.1 Media bed

Media beds are the grow beds which consist of gravel, clay balls, pumice stone and other stones which help in growing the plant. The plant grows in the rock media bed when it is filled with the water from the fish tank. The ideal depth of the media bed should be around 30cm to hold the root mass. The way to run the system is flood and drain. Media beds are designed in such a way that, the bed is filled slowly, and it drains quickly when the water reaches the appropriate level. Such function helps to aerate the roots and microbes. This process continues and provides regular nutrients for the plants to grow without any chemical added.

Figure 4: Media Bed (Source: Japan Aquaponics,2020)

4.1.2 Flood and Drain

Flood and drain are the cheapest and widely used systems in hydroponics. This system helps in maintaining the environment of the plant without damaging other plants. In this system, the nutrient rich water which was collected in the tray or in the media bed is pumped out to the reservoir to be reused. This process is also favorable for process automation, as it only needs occasional supervision and maintenance after it has been assembled in the system. 14 (42)

Figure 5: Flood and drain (Source: The spruce, 2020)

4.1.3 Nutrient Film Technique (NFT)

Nutrient film technique is the system where a nutrient solution flows in an enclosed gutter with almost 2cm depth of water. The main advantage of the system is the redistribution of the growth medium and the absence any media. Being process automation this process saves labor costs and the density of plant can be managed during crop cycle. Drawbacks of the system, clogging may stop the pumps and electricity as it has the low water level and fluctuations in the nutrient solutions may lead the plant to be attacked by diseases.

Figure 6: NFT system. (Simon et al. 2019, 91)

4.1.4 Deep Flow Technique (DFT)

The process of growing plants on a surface which is floating with support like rafts or board in a tank or storage filled with nutrient solution is deep flow technique (DFT) which in other word called as deep water technique (DWT). Approximately 20-30cm depth tank is required for the solution to be recirculated and oxygenated. This system can be built with various materials found in the market with 15 (42)

waterproof films. The plant needs support to grow above the water so floating raft are used so that the roots of the plant can penetrate the water.

Figure 7: DFT with floating panels. (Simon et al. 2019, 90)

4.2 Recirculating Aquaculture System

Aquaculture is the process of growing aquatic creature, both animals and plants in a fruitful environment. Small ponds, oceans, lakes, and rivers are the means where aquaculture can be done, from where we get the benefits of producing foods, conserve endangered species and fish culture. Aquaculture is one of the fastest growing agricultural industries, with the rates of 30% per year in comparison with arable farming or livestock rearing. There are different forms of aquaculture which are mariculture, fish farming, algaculture and integrated multitrophic aquaculture which has their own importance.

Integrated agri-aquaculture system (IAAS) has a wide range in which aquatic animal and plant production technologies come under. Aquaponics follows the vast range of IASS but is highly connected with recirculating aquaculture system (RAS) with hydroponic system. Conserved and standard methods are adopted by the RAS technologies for the fish. To manage the water purity in the fish tank filter is used to ensure the perfect environment for fish (i.e. removal of the solid waste and dissolved ammonia to maintain the oxygen level). Conserved and standard methods used by hydroponics and substrate culture technology for the consumable plants within an aquaculture. (i.e. flow of water in the system help the plants to gain the nutrients that they require for the growth). (Simon et al. 2019, 115)

The mixture of aquatic environment and hydroponics is aquaponics. This is the system where two ecosystems combine to create an environment for plants to grow without using chemical fertilizers or pesticides.

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Figure 8: Aquaponics cycle. (Japan Aquaponics, 2020)

The water quality decreases in the tank when the waste and ammonia produced by the fish remains in the fish tank. The grow bed is filled with the water from the fish tank where the ammonia is broken down by the billions of naturally occurring microorganisms to form Nitrite and Nitrate simultaneously.

The solid waste is filtered out either by filter or grow-beds, whereas plant absorbs Nitrate and other nutrients to clean the water. Clean oxygenated water is to be returned to the fish tank with improved quality. High quality of food is given by this natural and sustainable process.

In the aquaponics system, the stocking density of fish plays a vital role in running the system smoothly. The stocking density directly affect the fish and the plant growth as the quality of water is dependent on the density. To know the growth and production of fish an experiment was done on stocking density by the team of R. Rahmatullah, M Das and S.M. Rahmatullah in Bangladesh Agriculture Uni- versity (BAU), Bangladesh.

During the 15 weeks of the experiment in 2009 from April to August mono-sex tilapia fish of same age group were used. Equal sized of cemented cisterns were used for the experiment with the volume of 3.486푚3 and water level not exceeding 0.76m height. The experiment was done considering all the parameters required in an aquaponics system.

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Fish feeding also affects the stocking density so during the process the stocking density was created as three treatments (T1, T2 and T3)106 fish/푚3, 142 fish/푚3 and 177 fish/푚3 by taking uniform sized fish (0.76g). The fish feeding process was carried out as three times a day in the beginning with 25% of food containing protein. The feed rate was reduced as the bodyweight increases. (R. Rahmatullah et al, 2010)

Treatment Weight gain Weight gain SGR (% per FCR Survival Production (g) (%) day) rate (%) (kg/푚3) T1 32.67±2.19 4298.68±30.86 3.59±0.012 2.19±0.026 99±1.0 3.52±0.03 T2 24.54±1.83 3228.95±47.39 3.32±0.01 2.41±0.015 98±1.0 3.52±0.035 T3 19.41±1.27 2553.99±63.04 3.09±0.001 2.69±0.023 96±1.73 3.43±0.01 Figure 9: Effect of stocking density and growth (R. Rahmatullah et al, 2010)

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5 AUTOMATED SYSTEM DESIGN

The automated system design contains the major equipment required for the automated system. This section explains the lights used for the growth of plant during its initial stage, how the image in the section is considered to get meaningful information, the use of the best robot in the system and the water parameters that affect the system.

5.1 Grow light

The most important thing for the germination or for the plant to grow is light. During this period the right amount of light is required in order the plant to be grown as in the natural environment. Different plants require different light intensity for example some plants need full sunlight whereas some needs partial sunlight. So, according to that, the light is managed in this process.

Light is the main source of food for the plant. In this aquaponics system, the section of germination requires grow lights. The first week of the food production unit does not require much light because the seeds are turning into seedling and after the seedling light plays an important role for the growth of the plant horizontally when the light is evenly distributed to all the plants. After the second week the plants need grow light because the intensity of light in that section is low. The arrow shown in the figure 10 indicates the section of grow light. The section of grow light continues until the end of the germination section.

Figure 10: Area of grow light

There are different kinds of grow lights which can be found in the market. Every light has its own advantages and disadvantages for example fluorescents, incandescent, CFL, LED, MH, etc. According to the friendly aquaponics LED lights have more advantages than others. There is no risk of fire as it 19 (42)

does not produce any heat only emits light which is required for the plant, long life, low energy consumption and no mercury in the light. It is expensive in comparison to other grow lights and might not be suitable for all kinds of plants are some of its drawbacks.

5.2 Machine vision

Machine vision is the process of taking pictures and showing them in a user friendly interface. The light energy reflected from any light emitting object can be captured digitally. Pixel is the smallest component of digital image which has concentration of electromagnetic waves. The represented value of intensity for grey image ranges from 0-255 (Moeslund, 2012). Filter red, green, and blue filters the actual picture and combo of these colours symbolize all other colours. Important aspects of digital image are optics, pixel and reflected light from object.

One of the important aspects of this automated aquaponic system is that how the defected plants and defects in the system are monitored and how necessary actions are taken to solve the problems. The vision caught by two cameras in the systems solves all these problems. The camera captures the image from different locations and helps by detecting the fault. The camera is along with the track system with robot so that it can get perfect 180 degree view of the system and the robot take action to make the process correct by for example if a dead plant is detected by the camera after processing a command to robot is sent to remove the plant.

Figure 11: Camera

5.3 Robotic arm

The aquaponics system automation ideally requires a robotic arm to run the system automatically. For planting, harvesting, and moving the object from one place to another either manpower is required 20 (42)

or a tool so, this system contains a robotic arm to reduce the human effort and to make the system automated.

The mechanical system works as human arm, but its operation is based on pre-written programs without human interaction. It is used for production, processing, and various fields (Howstuffworks,2020). Based on kinematics there are two types of arms one is a serial arm, and the other is a parallel arm.

5.3.1 Serial robot

The robotic arm mechanism which consists of links that are connected in the serial sequence by different types of joints such as revolute or prismatic is called a serial robot. One end which is known as base is connected to the floor and another end which is known as end-effector is designed to move freely in each space. The effector has a gripper or mechanical hand (Pandilov & Dukovki, p. 146). The links are connected by many joints and this form is known as kinematic chain (Iitk, 2020).

The main five geometric serial link robots are SCARA (selective compliance assembly robot arm) (RRP), spherical (RRP), Cartesian (PPP), cylindrical (RPP), articulated (RRR) (Pandilov & Dukovki, p. 145).

In a serial robotic arm, kinematic structure is in the open loop-chain (Figure 12).

Figure 12: Fully Assembled Serial Arm (Iitk, 2020).

5.3.2 Parallel robot

The structure arms are connected through prismatic joints. The end effector of prismatic joint is fixed in a base by independent kinematic chains which is created by two or more closed loop. There are serial chains (also known as limbs or legs) in between base and end-effector (Pandilov & Dukovki, p. 150). The division of parallel robot are classified into degree of freedom where it can reach, total arms 21 (42)

and its joints with actuator (Mirshekari et al, 2016). As shown in the figure 13 the parallel arm robots are in a closed loop than open kinematic chain.

Figure 13: Fully Assembled parallel Arm (Iitk, 2020).

5.3.3 Attribute of serial and parallel robots

Both kind of robots have their advantages and limitations. In the table below the characteristics between a serial robot and a parallel robot are compared.

Feature Serial Robot Parallel Robot Workspace Large Small and complex Solving forward kinematics Easy Very difficult Position error Accumulates Average Force error Average Accumulates Maximum force Limited by minimum actuator Summation of all actuator force forces Stiffness Low High Dynamics characteristics Poor, especially with increas- Very high ing the size Modelling and solving dynamics Relatively simple Very complex Inertia Large Small Areas of application A great number in different ar- Currently limited, especially in eas, especially in industry industry Payload/weight ratio Low High Speed and acceleration Low High Accuracy Low High Uniformity of components Low High Calibration Relatively simple Complicated Workspace/robot size ratio High Low Figure 14: Attribute of serial and parallel robots (Pandilov & Dukovki, p. 146). 22 (42)

The comparison of two robots shows that each robot has its own specific advantages, which help by completing the given tasks considering their characteristics. The robot which has larger workspace, flexibility and which can handle the ideal weight was chosen as the robot for the system.

Universal robot UR3 was selected for the automated aquaponics system. The UR3 robot is small robot which suits in small and light weight applications. The robot weighs around 11kg at its working position and can carry a 3 kg load. It can rotate 360 degrees in both directions on all wrist joints and there is no barrier for the end joint rotation. It can reach up to 500mm in radius with high precision. (Universal robot,2020)

Figure 15: UR3 robot

5.4 Process parameters

Water parameter is monitored in aquaponics farming by taking water sample from any point of the system, which is the benefit of aquaponics farming comparied with soil-based farming. There are several parameters which affect AS. Some might affect the system immediately after something bad has happened in like reduced in dissolved oxygen level and some might take long time to affect the system. There are many factors which affect the system some of them are amonia, water temperature, total dissolved solids, pH value.

The important thing for the survival of fish in a fish tank is oxygen. Not only it is important for the fish, but it is equally important for the plants, the worms, and other benificial microbes. Extra oxygen in the system results in healthy plants and healthy fishes. There are many factors affecting dissolved oxygen in the fish tank such as temperature, altitude and biometric pressure, salinity, and biological activity like decomposing of plants and fishes. So, to ensure healthy environment around the system 23 (42)

dissolved oxygen must be checked regularly. Temperature of water or the system also affect the level of oxygen.

According to the season the temperature of the water might vary. The average temperature of the system is dependent on types of the fish and types of plants which are grown. For example, trout fish survive in cold climate and needs cold water whereas tilapia needs warm water and it is same with the plants as well because seasonal plants might be affected by the temperature of the water. Similarly, the bacteria and worms are also affected by the temperature which plays vital role for the growth of the plants. Monitoring of the temperature must be done so that the water temperature remains same all the time. With the fluctuation of temperature in water there might be some fluctuation in pH scale too as the deceased plants and fishes raise the scale of acidity and basicity.

The fish and the plants have their specific pH range like temperature in which they can survive. 0-14 is the range of pH scale, 7 is pure water and below 7 is acidic whereas above 7 is basic. The aquaponics system has four living things which share same ecosystem. The fish, plants, worms, and bacteria along with their different pH range 6.8-7 for their survivable. Bacteria plays a vital role in changing the pH of the water when it reacts with the food of the fish and helps in regulating nitrogen cycle. So, regular checking of the water must be done in this case and buffering agent must be added in the system if the water is acidic or basic.

The nitrifying bacteria present in the system reacts with the food waste and decreased fish produces ammonia in the system. Fish also eject ammonia through the gills and urine. Ammonia forms nitrite and nitrate both found in nitrogen cycle so, ammonia is the source for the nitrogen cycle. The first step of the nitrogen cycle nitrite is formed by the formation of nitrifying bacteria Nitrosomonas which

is than converted into nitrate by the formation of nitrifying bacteria Nitrobacter. Un-ionized ( 푁퐻3) + + and ionized (푁퐻4 ) are two forms of ammonia. 푁퐻3 is extremely harmful to fish, and 푁퐻4 is harmful + only at excess level. The pH and water temperature affect the ratio of 푁퐻3 and 푁퐻4 . The fish can

survive higher 푁퐻3 if pH of the water is below 7.

Total dissolved solid (TDS) in the water reflects the quality of minerals dissolved in it. The solid dissolved in water are as ions, molecules, or tiny particles. The increase of TDS means the quality of water is degrading or the water is not suitable for fish and plants and it also gives clear information about the nutrients that the plants are getting. (Bernstein 2013, 128-140.)

6 DESIGNING AN AUTOMATED AQUAPONICS FARM This section explains how different part of the automated aquaponics system were designed, and how different sub assemblies to main assembly. The fish tank, filter, tanks, robotic arms, and basically all elements of aquaponics system design which help in making the system automated. The work of fish 24 (42)

net and wiper in the fish tank with mechanical filter, reservoir system and the distribution of water with all the connection as a closed loop are described.

6.1 Fish Tank

The important aspect of aquaponics farming is fish which provides enough minerals for the plant. Different kinds of tank are used for the farming of fish. Most common fish tanks are oval. In this system a rectangular fish tank was used with a fish net attached in the tank. This fish tank is suitable for the system because it directly comes under the frame of the system. It is easier to run fish net linearly in a rectangular tank than in circular tank for harvesting. To control the water flow in the tank there is one incoming and one outgoing point. The incoming point coming from distribution tank whereas, the outgoing point is connected through T shape pipe to filter. The bed of the fish tank is slightly slanting so that the waste in the tank rolled down to the open area. The fish tank has only one small open area from which harvesting, and cleaning can be done. The wiper attached in the net- mechanism helps to cleans the fish tank.

Figure 16: Fish tank with net and wiper

A fish net is attached with the fish tank for harvesting the fish. It is driven by a motor along rack and pinion. Instrumental ball bearing is attached on both sides of the fishnet holder which goes into the groove in fish tank helping the fishnet move smoothly. For harvesting, ideal size fish are trapped in the fishnet. Other small and young fishes can escape through it. It covers entire width of the tank so there is no other way to escape for adult fish. Wiper is attached in the fish net to clean the bed of the fish tank. The wiper moves linearly up and down by the help of spring. Whenever the motor drives the fishnet the spring pushes the wiper downward maintaining the surface level. When the motor is 25 (42)

driven during the time of harvesting the wiper clean the food waste and maintains cleanness. The movement of the fishnet and wiper makes the food waste move around and the waste moves towards the filter via the attached pipe.

Figure 17: Fish net and wiper with surface spring

6.2 Mechanical filter

The purpose of the filter is to filter the water coming from the fish tank. Due to cylindrical shape and conical base the water moving in circular direction pushes the heavier suspended particles to settle down in the middle of the tank. Fish tank and filter are in the same level and attached with T shaped pipe in which one point is connected to filter and other end is submerged in the tank and one point is above the water level maintaining the air pressure to flow the water towards the filter. All the waste from fish tank comes and is collected in the filter and only clean water flows to the sump tank. The clear water from the filter goes to the sump tank which relates to an elbow joint pipe. The point of elbow is placed above the point from which water comes in the filter so that the waste coming from the fish tank gets time to settle in the filter. A small hose is attached to the bottom of the filter to take out the waste collected in the filter.

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Figure 18: Filter

Two water tanks are used in this system to create pressure difference or to provide head high. Sump tank is placed beneath the filter so that the water flows into the tank with gravity. Distribution tank is placed on top so that the water can flow in the system with gravity. One motor is placed to get the water from the sump tank to the distribution tank. These tanks are also used as reservoir tanks.

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Figure 19: Reservoir tank

6.3 Gripper attachment

Universal robot 3 (UR3) was taken into consideration for this system as it covers the working area of the system. It can hold the ideal weight required for the system about 3-5 kg. The arm is suspended vertically downward so that it can maximize the working area of around 50cm along all direction. The arm moves around 6 axis maximizing its working area. There are three tools used by the robot to perform its task which are hand gripper, claw gripper and seeding nozzle. Each tool is attached in the arm by the help of electromagnetic induction.

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Figure 20: Universal robot 3 (UR3)

6.3.1 Hand gripper

The most used tool by robotic arm is hand gripper. From holding seeds jar to picking up the plant during harvesting, it performs in systematic order. Beginning with holding the seeds jar for seeding the tray. It takes out and disposes of the damaged plant detected by the camera. The two claws grab the plant and put it in the storing tray.

Figure 21: Hand gripper

6.3.2 Seeding nozzle

The only work of seeding nozzle is to put the seeds in the tray. Seeding nozzle at first sucks the seeds by the help of vacuum and pours the seeds in each small square of the tray. One seed in one square 29 (42)

so that there is no waste of seeds and this helps in growing the seeds freely. If there are too many seeds in a small square there is no room for them to grow.

Figure 22: Seeding nozzle

6.3.3 Claw gripper

Claw grippers are used to lift or carry the seedling tray. After seeding the tray claw gripper takes the seedling tray by holding it in the middle of the tray so that it does not falls apart.

Figure 23: Claw gripper 30 (42)

Figure 24: Seedling tray with gripper hole

6.4 Plumbing

One of the main parts of this system is plumbing, which helps in maintaining the closed loop and controls the flow of water. This system helped the water to flow from fish tank to the bed and vice versa. Valves are used to control the flow of water. Pipes connect the fish tank and filter, which is connected to the small reservoir. In the small reservoir or sump tank there are two points from which clean water comes in and one point from which water goes out by the help of motor in the upper reservoir or distribution tank. The two incoming points for the small tank are from grow bed and filter. For the upper reservoir there are three outgoing points and one incoming point which is on top of the tank connected to motor. From three points one point goes to the bed, one goes to fish tank and one goes to the germination area where there is small release point for the area.

Figure 25: Plumbing

The water flow system is driven by only one motor with positive pressure from sump tank to distribution tank, other all process is carried out by the help of gravity or drained by gravity. The flow of water is downward from Distribution tank to grow bed and fish tank so, no medium is required for this process to push the water downward. Valves are used to control the flow of water.

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Figure 26: Gravity flow system

6.5 Conveyer belt stand

The entire system is automatic so to fill the seedling tray and to align with the hydraulics table. The conveyer belt is driven by stepper motor. This system is used to fill the seedling tray with a sand. The entire system consists of sand holder, auger, motor, compressor roller, seeding tray and conveyer belt. Top of the table sand holder holds the sand and is uniformly distributed by spinning auger which rotates by the help of stepper motor. The tray moves after it is filled with the sand and roller compressor compresses the sand before seeding the tray.

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Figure 27: Conveyor belt system

For filling the seedling tray with sand from the sand holder an auger is used. Auger helps in maintaining the flow of sand in the seedling tray. An attached motor rotates an auger and the sand drops down through its path. An attached blade will distribute the sand uniformly in the tray. There are three blades which covers the entire tray so that the sand is equally poured in each hole of the seedling tray.

Figure 28: Auger

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Seedling tray is the tray where saplings are grown for the farming, which is also the first step for the farming. UR3 robot is used for the seeding in the tray and auger slides down the sand and blade make it uniform. Roller compressor compresses the sand in the seeding tray so that it has a compact sand.

Figure 29: Seedling tray

Figure 30: Roller compressor

6.6 Hydraulics table

Two hydraulic tables are used as a working table front and back. It is used by the robot for the seeding purpose in the tray and during harvesting. It manages suitable position for sliding seedling tray from the conveyer belt to the table and comes to the position where the robotic arm can reach. The table align its position with the roller in the frame to ease the process of letting and getting out for the seedling tray.

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Figure 31: Hydraulics table

6.7 Pump and motors

There are altogether four motors to drive the system. AC motor driving fishnet in a linear motion with the help of rack and pinion. Two stepper motors are used in the conveyer belt system to run the conveyer belt and to run the auger both in circular motion. One Hz power AC motor is used to pump water from sump tank to distribution tank.

Figure 32: One HP motor

Similarly, two air pumps were used for the fish tank and grow bed to maintain the oxygen level. Here instead of one air pump two are used because in case if one of pump stops working another can pump the air in the system.

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Figure 33: Air pump

The air pipe is used to pump air or oxygen into the fish tank and in grow bed. The pipe is connected to the air pump which blows the air in the water. The air pipe covers maximum volume of the tank and bed because it is designed by calculating the length and width so that the pumped air scatter equally inside water.

Figure 34: Air pipe and stone 36 (42)

The small stone attached to the air pipe which creates small bubbles in the water is air stone. The air stone is attached with the pipe so that the tiny holes in the air stone generate bubble in the water when air is passed.

Figure 35: Air stone

6.8 Frame and roller

Many important things for the aquaponics are setup in the frame shown in the figure. From DWC bed to small trays which hold the working tools of robot. The frame is so designed that it can utilize every space that it covers. Vertically it has three section, the lower one consists of the roller which is below the main bed. The roller section is designed for the germination of the seedling. From one point seedling tray is feed inside the roller and after 28 days it is taken out by the help of robot and kept in the bed for another 28 days until it is ready for harvesting which is also the second section of the frame.

Figure 36: Frame and roller

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On top of the frame there is a track system for the robot movement. Two tracks are designed in such a way that it gets the access to the entire bed and outside the area of bed to pickup and harvesting. The distance is calculated while placing the two tracks in the frame so that the robotic arm gets 0.5m access on both sides. It is a closed loop system which makes easier for the movement of robot.

Figure 37: Robotic track

6.9 Design Summary

The purpose of this project was to combine two soilless agriculture methods to produce food acquiring less area. The important thing in this system is the flow of water, which must circulate the system repeatedly containing nutrients and oxygen for the plants and fish. The design started with the fish tank and its sub assemblies as its first part.

The integral part of this system is fish tank, which has all the required minerals and nutrients for the plant. A rectangular fish tank was designed for this system with a fishnet and a wiper. Slanted base of the fish tank has 30cm height which helps in rolling down the fish waste in the base. An ac motor is used to drive the fishnet linearly forward during the time of harvesting and the wiper moves linearly down along with the fish net by the help of surface spring. After the harvesting the fish net and wiper take their original position to rest. Freshwater fish like trout and tilapia are considered in this system. The fish tank contains food and fish waste so to clean the water a filter is added in the system.

The filtered water is collected in the sump tank by gravity flow, so no medium is required to collect the water into the tank. Motor is used to collect the water from sump tank to distribution tank and other all process of water distribution is on gravity flow. Deep water culture bed, fish tank and in germination section the water is distributed from the tank. Valves are added in each section to control the flow of water. The over flown or clean water from the deep-water culture bed is collected in the sump tank and the process is continued in the same way as a closed loop.

After the regular water circulation in the system the seedling trays are prepared with seeding them by robotic arm. The tray is prepared in conveyer belt stand with sand pouring in the tray by an auger 38 (42)

and distributing it in the hole uniformly by the help of blade. To make the sand compact roller compressor compresses the sand in the tray so that the roots of the plant grab the sand during germination. The tray then moves towards the hydraulic table which maintains the same level with the conveyer belt. In the table robotic arm uses its different tools for the seeding purpose. Hand gripper grabs the seed jar and brings to the table and seeding nozzle is used for seeding in the tray. After seeding the tray, the robotic arm changes its tool and gets another tool claw gripper which holds the seedling tray and move from one place to another i.e. to the table and the table adjust its position so that the handle can pull the tray inside the germination area. The roller acts as the base for the tray in the germination area so that the trays can move easily forward whenever seedling trays are fetched inside.

The germination section has different departments as the seeds grow from sprouting to seedling and then sapling. Bok choy is the plant that is grown in this aquaponic farm. Firstly, sprouting of the seeds in the seedling tray takes a week and is completed in the dark area. Light is not required during the first week as the seeds can sprout in the dark. After sprouting to seedling and sapling of the plant enough light is required which is why this section has grow light. The intensity of light in this section is low and the plant does not grow properly so the grow light helps the plant to grow healthy as it can get enough light. There are different water points in this section which pour the water in the plants so that the plants get moist all the time. After four weeks in the germination section the plant is ready to be grown in the grow bed and is transferred. After each week the Seedling tray is filled and pushed into the germination section. So, after each week there is an outcoming plant that needs to be kept in the bed. In the outcoming area there is a hydraulic table which maintains the position with the roller and the tray slides into the table.

The hydraulic table maintains its height until the robotic arm can get the tray. Robotic arm uses its tool hand gripper to transfer the plant to the Styrofoam in deep water culture bed. The distance between one plant to another plant is maintained in the Styrofoam and acts as the tray for the plant. The Styrofoam floats in the water which help the roots of the plant submerged into the water and can get enough nutrient. In between this process the camera monitors every action of the plant growth. If any plant is damaged, then the camera detects and sends signal to robot which then pick the plant and disposes. In this way in four weeks time the plant is ready for harvesting. The robot picks the well-developed plant and put it in the storage tray.

Overall, the design of the automated aquaponics farm gives a complete outlook of how the system works. Each part has its own importance in the system and the system is incomplete if any of them is removed from the system for example robotic arm or fish tank and so on.

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7 CONCLUSION

The aquaponics farming itself is an upgraded technology or hybrid technology of hydroponics and aquaculture. The combination of two food production systems in a closed ecosystem gave an idea for the hands-free farm and the steps were taken accordingly.

Designing the working model of automated aquaponics system was the main goal of this project. The design part was divided into many different sections. Designing of small components to big frames and their assemblies. For example, the fish tank has its own assemblies with fishnet motor and wiper which is connected to the entire system by pumps and pipes. Similarly, conveyer belt has seedling tray and sand which are run by a motor and controlled by robotic arm.

The automated aquaponics system operation consists of fish in fish tank and the water from the fish tank circulating inside the system as a closed loop. The automatic process starts with filling of a seedling tray with sand. After seeding the tray by robotic arm and dragging it by the conveyer belt to the tray table the hydraulic arm pulls the tray to the roller system which is first stage of germination section. Robotic arm moves the sapling to grow bed after it comes out from the roller system.

Lifting and seeding the tray, picking up the damage plants, and during harvesting, UR3 robot is used. This robotic arm is way more effective than any other for this system as it is easy to use and well configured. The best part of this robot is it can cover 360 degree rotation on all wrist joints, covers 50cm wide range and can carry ideal weight of 3kg required for the system. This robotic arm helps in making the system automatic by all the lifting and picking.

Most of the aquaponics system parameters match with the process automation. One sample from the water can give the data of the entire ecosystem of aquaponics. There are many benefits of acquiring automated aquaponic farming, in small space rearing of fish and growing of the plants are possible and can produce more amount of foods than in soil-based farming. A robot monitors the system and detects the decaying or damaged plants and prevents others from getting damaged. Water quality can be controlled if the water quality gets degraded by the decease of fish or sudden changes in the pH scale. The water in the fish tank and in the distribution, tank can be controlled by avoiding overflow and drain in the system.

Likewise, the fish tank, tanks and filter are heart of the system, without these the system cannot run and are interrelated. Sump tank and distribution tank work as reservoir tank and helps in flowing the water to the entire system. Filter is used to filter the water coming from the fish tank so that the sump tank does not get any sludges which might block the flow of water pumped by the motor. The water from distribution tank is connected to every point of the system. The water is continuously flowing from distribution tank to fish tank, grow bed, from fish tank to filter and from filter to sump tank. The cycle uninterrupted and the quality of water is same in all department.

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However, the aquaponics has a filter in the system yet the quality of the water for both plant and fish is affected by the presence of small organism bacteria and worms. The reaction of the fish food with water and fish itself ejects ammonia as waste which in long term degrades the quality of water. So, the quality of water must be maintained by looking at the water parameter. It is dangerous for both plants and fish if the water is more acidic or basic or the oxygen in the water is less because same water is moving all the time in the system. The water from fish tank has food for the plants whereas, plants also filter the water and sends to sump tank. The advantage of the system is that one sample of water gives all the data and can easily be controlled.

Overall, the automated aquaponics system has some space for the improvement in the future. This system has covered almost every aspect of the initial stage of being a handsfree system. The development of the system could be continued through after the prototype has been built. Increasing the working area for robotic arm can be done so that it is busy most of the time. Duties of robotic arms can be harvesting of the fish and controlling the quality of water if necessary.

All in all, the project from ‘One Farm Nepal’ helped author in unleashing the ideas for the automated aquaponics system and boosted the knowledge in designing and generating different ideas for the project. Also knowledge about the soilless farming and how it can take over soil-based farming in the future was gained.

Figure 38: Complete model

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