design of an aquaponic system

81 Pages·2015·2.22 MB·English

UNIVERSITY OF NAIROBI
SCHOOL OF ENGINEERING
DEPARTMENT OF ENVIRONMENTAL AND BIOSYSTEMS ENGINEERING

FEB 540: ENG INEERING PROJECT
2014/2015 ACADEMIC YEAR

REPORT

PROJECT TITLE: DESIGN OF AN AQUAPONIC SYSTEM

CANDIDATE NAME: WAMBUA LYDIA WAYUA

CANDIDATE NO: F21/1731/2010

SUPERVISOR’S NAME: MR. S.C ONDIEKI

DATE OF SUBMISSION: 29Th MAY, 2015

A Report Submitted in Partial Fulfillment of the Requirements of the Degree of Bachelor of

Science in Environmental and Bio Systems Engineering of
University of Nairobi

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DECLARATION

I declare that this project is my original work and has not been submitted for a degree in any
other University.

Sign ………………………………….. Date…………………………………………..
(Wambua Lydia Wayua)

This project report has been submitted for examination with my approval as University
supervisor.

Sign …………………………………… Date…………………………………………
(MR. S.C ONDIEKI)
Supervisor

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DEDICATION

I dedicate this project to my family, for their never ending support throughout; to my friends for
their assistance, to my supervisor, Mr. Ondieki for his understanding and guidance. I finally
dedicate it to the prospect farmer in Kamulu, for her inspiration to me to carry out this project.

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ACKNOWLEDGEMENT

First and foremost, I extend my gratitude to God, for His ever presence and success.
Much esteem goes to my supervisor, Mr. Ondieki for his support and his tremendous knowledge
and skill toward my project till the end.
I also acknowledge the rest of the supervisors for their advice in class, and my friends for their
encouragement and support.
I acknowledge Mr. Daniel Kimani, an aquaponist, for his contribution to my project.

To all I say thank you and God bless you.

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ABSTRACT.
This report entails the designing of an aquaponic system. This is a system of simultaneously
growing crops and rearing fish on the same piece of land, whereby the fish and crops live in a
symbiotic relationship; the fish supplies nutrients to the crops while the crops clean the water for
the fish by removing ammonia (produced by the fish), which would otherwise accumulate to
toxic levels for the fish survival.
The design focus is to optimize the use of agricultural resources of land, water, as well as labour,
to make farming more sustainable. It addresses two issues; (1) the issue of limited land for
farming in the city and its outskirts and (2) low yields associated with inconsistent water and
nutrient supply.
Functional decomposition and synthesis method was applied for the conceptual design of the
system as a logical approach that describes the transformation between initial and final states of
the system, relying on restructuring the design task to a more abstract and comprehensive level to
promote greater access to the understanding of the system.
The alternatives produced by the functional decomposition were analyzed through a decision
matrix that facilitated the selection of the most suitable and customized system for the problem at
hand. The analysis and prioritization conducted for the alternatives was in accordance to the
ranking of the engineering characteristics obtained from the House of Quality.
Design criteria for aquaponic systems successfully applied to similar systems, especially by the
pioneers of aquaponic systems from the University of Virgin Islands have been applied in the
design. The engineering principles of fluid mechanics were used to determine the correct water
velocity and flow rate for fish swimming and fish tank self-cleaning, the required settling
velocity for sediments in the sedimentation tank, the required pressure to supply water to the
towers and the associated system head, head losses and pumping requirements. Material
selection was used to select the most suitable materials for the tanks and pipes. The layout of the
system and associated detailed drawings were drawn using AutoCAD.
For further up-scaling of the project and for environmental and financial sustainability, it was
recommended that solar or wind power should be enhanced as part of the energy source. Rain
water could also be harvested as an alternative source of water. Automatic fish feeding system
and mobile phone-control of the system is also recommended as steps toward automation of the
system as much as is acceptable. Other hydroponic design alternatives apart from vertical tower
system could also be applied for a given locality and project.

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Table of Contents
DECLARATION ............................................................................................................................ 2
DEDICATION ................................................................................................................................ 3
ACKNOWLEDGEMENT .............................................................................................................. 4
ABSTRACT. ................................................................................................................................... 5
CHAPTER 1 ................................................................................................................................... 9
INTRODUCTION ...................................................................................................................... 9
1.1 PROBLEM STATEMENT AND PROBLEM ANALYSIS ............................................ 9
Problem statement .................................................................................................................. 9
Hypothesis ............................................................................................................................... 9
Problem Analysis and justification ......................................................................................... 9
Converging point of aquaponics and the current soil farming ................................................. 13
1.2 SITE ANALYSIS AND INVENTORY ......................................................................... 14
1.2.1 Location ....................................................................................................................... 14
1.2.2 Climate ......................................................................................................................... 15
1.2.3 Water supply ................................................................................................................ 16
1.2.4 Electricity supply ......................................................................................................... 16
1.2.5 Farming........................................................................................................................ 16
1.2.6 Significance of the site ................................................................................................. 16
1.3 OVERALL OBJECTIVE ............................................................................................... 17
1.3.1 SPECIFIC OBJECTIVES........................................................................................ 17
1.4 STATEMENT OF SCOPE............................................................................................. 18
CHAPTER 2 ................................................................................................................................. 19
LITERATURE REVIEW AND THERORETICAL FRAMEWORK ..................................... 19
2.1 Literature Review................................................................................................................ 19
2.1.3 Nutrient source for hydroponics and aquaponics ........................................................ 19
2.1.4 System design ............................................................................................................... 20
2.1.5 Overview of unit operation ..................................................................................... 21
2.2 Theoretical framework ........................................................................................................ 32
2.2.1 Sizing the hydroponic growing area ............................................................................ 32
2.2.2Sizing and design of the fish rearing tanks ................................................................... 32
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2.2.3 Tower development ..................................................................................................... 35
2.2.4 Settling basin design details ......................................................................................... 35
2.2.5 Aeration requirements .................................................................................................. 36
2.2.6 Pump sizing .................................................................................................................. 36
2.2.7 Piping ........................................................................................................................... 37
CHAPTER 3 ................................................................................................................................. 41
GENERATION OF CONCEPT DESIGN ................................................................................ 41
4.1. Overall Functional decomposition and synthesis .............................................................. 41
4.2 Functional decomposition and synthesis for this project .................................................... 42
4.3 Generation and analysis of alternative solutions ................................................................ 43
4.3.1 Selection of a hydroponic system ................................................................................ 44
4.3.2 Selection of the solids removal devices ....................................................................... 45
4.3.3 Selection of the fish culture tank ................................................................................. 47
4.3.4 Selection of an aeration device .................................................................................... 47
4.4 Generated conceptual design .............................................................................................. 48
CHAPTER 4 ................................................................................................................................. 49
METHODOLOGY ....................................................................................................................... 49
CHAPTER 5 ................................................................................................................................. 54
RESULTS ................................................................................................................................. 54
CHAPTER 6 ................................................................................................................................. 71
6.1 CONCLUSION ................................................................................................................... 71
6.2 RECOMMENDATION .......................................................................................................... 74
6.3 REFERENCES .................................................................................................................. 75
APPENDICES .............................................................................................................................. 77
Appendix A ............................................................................................................................... 77
Appendix B ............................................................................................................................... 80

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List of figures
Figure 1: Bar chart showing Hydroponic vs. Conventional Farming ........................................... 11
Figure 2: Maps showing project location in Kamulu area, Nairobi, Kenya ................................. 14
Figure 3: Chart showing Kamulu average temperature ranges from 2000-2013.......................... 15
Figure 4: Graph showing the average temperature and the rainfall pattern of Kamulu ............... 16
Figure 5: Photo of commercial aquaponic farming using vertical towers .................................... 19
Figure 6: Optimal arrangement of aquaponic system components ............................................... 21
Figure 7: Common rearing tank shapes ........................................................................................ 21
Figure 8: Settling basin ................................................................................................................. 24
Figure 9: Radial flow separator..................................................................................................... 25
Figure 10: NFT System ................................................................................................................. 27
Figure 11: Raft system .................................................................................................................. 28
Figure 12: Aeroponic system ........................................................................................................ 29
Figure 13: Ebb and flow system ................................................................................................... 29
Figure 14: Vertical system ............................................................................................................ 30
Figure 15: Growing area 15 x 8 m ................................................................................................ 55
Figure 16: Front and side view of a single tower.......................................................................... 56
Figure 17: Drawing of one fish tank layout .................................................................................. 61
Figure 18: Sketch of a settling tank .............................................................................................. 63
Figure 19: Sedimentation tank layout ........................................................................................... 64
Figure 20: System layout .............................................................................................................. 70
Figure 21: Moody chart ................................................................................................................ 78
Figure 22: House of quality most complete configuration ........................................................... 78
Figure 23: Data collection photos ................................................................................................. 80
Figure 24: Google earth map showing the elevation of the farm ................................................. 80

List of Tables
Table 1: Cost-Benefit Analysis ..................................................................................................... 13
Table 2: Exclusion screen sizes .................................................................................................... 35
Table 3: Circulation- drains/pumped return line ........................................................................... 38
Table 4: Decision matrix for a hydroponic system ....................................................................... 45
Table 5: Decision matrix for a solids removal device .................................................................. 46
Table 6: Analysis of fish tanks...................................................................................................... 47
Table 7: Bill of Quantities............................................................................................................. 73
Table 8:The aquaponic House of Quality streamlined configuration Rooms 1,2,3,4 and 5 ......... 79

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CHAPTER 1
INTRODUCTION

1.1 PROBLEM STATEMENT AND PROBLEM ANALYSIS
Problem statement
The project is designed to addresses two major issues; (1) The issue of limited land for farming
in the city and its outskirts and (2) Low yields associated with inconsistent water and nutrient
supply.
Hypothesis
An aquaponic system can grow 90% more food on 90% less land.
It optimizes agricultural resources of land, water, nutrients and labour, consequently optimizing
yields, income, and the selection of the best enterprise for a potential farmer.
Problem Analysis and justification
Significance of Agriculture to Kenyan economy
Agricultural sector in Kenya is the largest employer in the economy, accounting for 60% of the
total employment. It directly contributes 24%of the GDP and indirectly contributes 27% through
linkages with manufacturing, distribution and other service related sectors. 45% of government
revenue is derived from agriculture. It contributes over 75% of industrial raw materials and 60%
of export earnings. About 80% of the population living in the rural areas derives their livelihoods
mainly from agricultural activities.1 Yet agriculture still faces a number of challenges.
Current challenges in agricultural development in Kenya
The key challenges include:
o Agriculture is the mainstay of the economies but is practiced at subsistence scale
with low levels of commercialization
o Low adoption of improved technologies/innovations leading to low productivity
and fragile resource base
o Overreliance on labour intensive and low productive agricultural technologies

1
http://www.amshaafrica.org/projects-and-clients/current-projects/aquaponics-in-rural-kenya.html

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o Overreliance on rain fed agriculture, famines being a common problem due to
droughts
o Biotic and abiotic stresses for crops and livestock, leading to yields losses due to
pests, diseases, drought, natural resource degradation, etc
o Socio-cultural orientation among some communities where agriculture as viewed
as a non-commercial venture, and
o Reduced focus and /or low investments in agricultural ventures and training
Opportunities for development of agricultural sector
There is interest to make agricultural sector more competitive due to globalization. One of the
opportunities from the Kenyan vision 2030 is its interest in making agriculture a commercial
undertaking and creating development impact by recognizing that market driven and private
sector-led growth transforms agriculture. There are thus numerous opportunities from the
increased need to conserve and sustainably utilize natural resources to the need of adopting
technologies.
Adoption of Aquaponics
This is a system of farming that is independent on the soil type, and whose scale can be increased
on a limited land. It can thus be well applied in existing or upcoming urban settings, such as
Kamulu town in Kenya.
Aquaponics is a farming technique that combines the production of crops through hydroponics
and the rearing of fish though aquaculture. In aquaponics, any of the two systems can either be
the primary or the secondary component depending on the needs of the user.
Hydroponics has been recognized as a viable method of producing vegetables: tomatoes, lettuce,
cucumbers, peppers and strawberries as well as ornamental crops such as herbs, roses, freesia
and foliage plants. Aquaponics, which mimics the natural dynamics of all of earth's water ways,
is the only organic hydroponic method that has proven to be commercially viable. And, as an
added bonus, one produces two crops - fish and vegetables. The fertilizer in an aquaponic system
comes from the fish waste. Microbial activity converts the waste into nutrients that the plants
need and, as the plants consume the nutrients, they help to purify the water the fish live in. This
all happens in a recirculating system that uses less water than traditional agriculture.
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