IN
DEGREE PROJECT DESIGN AND PRODUCT REALISATION, SECOND CYCLE, 30 CREDITS
STOCKHOLM SWEDEN 2020,
Designing a proof of concept of an ecological dry boat toilet for
Swedish recreational sailing crafts
MALCOLM ROYEN
KTH ROYAL INSTITUTE OF TECHNOLOGY
SCHOOL OF INDUSTRIAL ENGINEERING AND MANAGEMENT
Designing a proof of concept of an ecological dry boat toilet for Swedish
recreational sailing crafts
Malcolm Royen
Master of Science Thesis TRITA-ITM-EX 2020:54 KTH Industrial Engineering and Management
Machine Design SE-100 44 STOCKHOLM
Examensarbete TRITA-ITM-EX 2020:54
Design av ett valideringskoncept av en ekologisk torr båttoalett för svenska fritidsbåtar
Malcolm Royen
Godkänt
2020-07-03
Examinator
Claes Tisell
Handledare
Martin Sjöman
Uppdragsgivare
Harvest Moon
Kontaktperson
Karin Habermann
Sammanfattning
Det här examensarbetet utfördes hos Harvest Moon som arbetar med metoder att ta tillvara på näringsämnena i toalettavfall och har utvecklat tekniker för dessa. Projektet skulle undersöka hur deras tekniker skulle kunna implementeras i svenska fritidsbåtar i form av en proof-of-concept toalett.
Först undersöktes användargruppen och dagens sanitetssystem inom svenska fritidsbåtar, genom litteratur inom ämnet samt intervjuer med användaren. Den grupp som skulle få mest värde av en toalett med denna teknik var segelbåtar och de två största problemen med dagens teknik var att man hade låg kapacitet på tanken och att det var problem med att tömma tanken.
Proof-of-concept utvecklades genom att utveckla en komponent i taget, där den komponent som var mest central och styrde andra börjades med för att mellan varje komponent titta på helheten.
Prototypbygge användes mycket för att testa komponenterna och få snabba svar på hur de fungerade. Arbetet skedde i nära samarbete med Harvest Moon och resultaten ingick i deras egna projekt som pågick parallellt.
Resultatet presenterades i CAD-modeller och illustrationer om hur arkitekturen såg ut, samt hur den var tänkt att användas. Det resulterande konceptet skulle ge användaren en mycket bättre kapacitet, vilket skulle resultera i längre tider mellan att man behöver tömma avfallet och en enklare och behagligare tömningsupplevelse. Avfallet skulle även lättare än dagens system kunna anslutas till ett system för att återanvända näringsämnena i avfallet.
Master of Science Thesis TRITA-ITM-EX 2020:54 Designing a proof of concept of an ecological dry
boat toilet for Swedish recreational sailing crafts
Malcolm Royen
Approved
2020-07-03
Examiner
Claes Tisell
Supervisor
Martin Sjöman
Commissioner
Harvest Moon
Contact person
Karin Habermann
Abstract
This thesis was performed at Harvest Moon who develops methods to reuse the nutrients in human waste and has developed technology for these methods. The project aimed to explore how their technology could be implemented in a boat toilet for the Swedish recreational market. It resulted in a proof-of-concept boat toilet.
Firstly, the user group and the current sanitation system were explored, through literature research and interviews with the user group. Sailing craft users were identified to be the user that would gain the most value with these technologies. The two largest problems for the users with the current system was a low septic tank capacity and problems emptying it.
The proof-of-concept was developed by developing one component at a time, starting with the most central component that most components were dependent on and between the components looking at the overarching architecture. To test the component ideas and gain quick answers to their functions rapid prototyping were used. The work was done in close collaboration with Harvest Moon and the results were continuously used in their own projects that were performed in parallel.
The results of the thesis were presented as CAD models and illustrations of the architecture and of the usage of the boat toilet. The resulting concept would provide the user with a better sewage capacity than current technologies, which would result in longer times between having to empty the toilet. It would also provide a simpler and more pleasant experience emptying the toilet. The toilet waste would also be easier to use in a system were the nutrients are reused than the current sanitation system.
FOREWORD
I, this thesis author, would like to thank,
Martin Sjöman for his support, supervision, valuable insights and feedback as well as keeping the project on track.
Karin Habermann at Harvest Moon for her supervision, support and all new knowledge.
Peter Thuvander at Harvest Moon for his support and widening my horizons.
Åsa Karlsson at Harvest Moon for her support.
Teo Enlund and Claes Tisell for their support throughout the work.
All the people I met at the fair who provided me with insights into the world of recreational crafts.
My family and friends for their love and support.
And last but not least, my sambo Malvina, for her love, support and great patience with me during this thesis work.
Malcolm Royen Stockholm, August 2019
TABLE OF CONTENTS
FOREWORD 5
TABLE OF CONTENTS 7
1 INTRODUCTION 1
1.1 Background 1
1.2 Problem description 2
1.3 Delimitations 2
1.4 Method 3
2 FRAME OF REFERENCE 5
2.1 Rules and regulations for human waste 5
2.2 Ecological sanitation 6
2.3 Human toilet related anatomy and waste 6
3 PRESTUDY 7
3.1 Current recreational craft sanitation 7
3.2 State-of-the-art mobile toilets 9
3.3 Harvest Moon technologies 13
3.4 About Swedish recreational crafts 13
3.5 User 14
3.6 Requirement specification 15
4 DESIGN PHASE 16
4.1 Technological feasibility 16
4.2 Component overview 16
4.3 Urine diverting unit and seat 17
4.4 Feces storage 22
4.5 Urine treatment components development 26
4.6 Exploring the product architecture 26
4.6 Final product architecture 27
4.7 Revisit Allt för sjön 28
4.8 Form 28
5 RESULTS 29
5.1 CAD renderings 29
5.2 Architecture 31
5.3 Usage 32
5.3 Factors and insights related to toilet design 34
6 CONCLUSIONS AND DISCUSSION 35
6.1 Conclusions 35
6.2 Discussion 36
7 REFERENCES 37
APPENDIX A: INTERVIEW GUIDES 38
APPENDIX B: INSIGHTS FROM INTERVIEWS 40
APPENDIX C: IDENTIFIED PROBLEMS WITH THE CURRENT
SANITATION SYSTEM 45
APPENDIX D: IDEAS FOR FLUSHING SOLUTIONS 49
APPENDIX E: SKETCHES OF CONCEPTS 51
APPENDIX F: PICTURES OF BOAT INTERIORS AND BATHROOMS 54
APPENDIX G: STYLE-GUIDE 56
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1 INTRODUCTION
This chapter contains an introduction to the project and includes, background, problem description, limitations and methodology.
1.1 Background
As the human population grows so does the need to use the earth’s resources in a sustainable way. Looking at the planetary boundaries concept one of the high-risk zones is the biogeochemical flows of phosphorus, nitrogen and carbon. These are essential nutrients for all life and are today used in a non-sustainable way. As humans consume food, most of the nutrients are excreted, mixed up with other wastewater and transported to the sewage plants. Most of it is leaked into the oceans and contribute to eutrophication, oxygen depletion and dead zones. The Baltic sea suffers greatly from these problems. Instead of this linear transportation of nutrients, the chain should if a sustainable future is preferred, be made into a cycle. The nutrients in the sewage could be taken care of and returned to the agriculture, reducing the need of artificial fertilizers, which in their production and use contributes to carbon dioxide emissions and soil depletion.
The nutrients in the sewage can therefore create monetary value. The urine contains a specific ratio of nitrogen, phosphorus and potassium which is ideal for most crops, and could be sold as fertilizer. The feces can be treated in numerous ways to produce insect protein, biogas and manure for example. They can also return carbon as organic matter back to the soil.
Harvest Moon has developed a way of collecting the nutrients from urine and feces and reduce the volume of the waste There are many areas where this technology could be useful and one of these could be the Swedish private boat community. Discharge of sewage in the Baltic sea from recreational crafts is banned since 2015, it should instead be collected at reception facilities. The municipalities have the responsibility to take care of the sewage and transport it to a sewage plant. Also, the technical and spatial prerequisites on boats can serve as a model for other contexts such as transportation and space travel.
Urine is the largest volume fraction of the sewage and by reducing the volume, the capacity of the boats’ tank would increase. This would result in longer time between visits to the reception facilities and that users would urinate in the boat toilet instead of on land. The technology makes the sewage easier and less messy to empty and could therefore be carried to the reception facility instead of relying on pump-out stations. It would also make it easier to follow the ban because many boat users experience that there aren’t any working pump-out stations when and where they need it, usually far out in the archipelago. There have been studies that have explored the effects of the ban and found that there are problems with the user experience, pump-out stations and how the sewage should be handled.
Harvest Moon has a vision to apply their technologies to create a scalable ecological sanitation system. They are interested to explore how their technology could be implemented in the development of a dry boat toilet that promotes a circular consumption of nutrients and at the same time add value to the user. This has not been investigated earlier and will be used as inspiration for further development.
Harvest Moon therefore wants to explore if dry ecological sanitation be designed to create user- value for boat owners.
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1.2 Problem description
The project will develop a product concept of a boat toilet using Harvest Moons volume reducing technology. The boat toilet should be designed to create value for the user. It will be part of the project to identify a user profile that would benefit most from this kind of toilet and design it for this user. The resulting concept should focus on concepts of components verified that they could function, they do not need to be detailed.
A simple service concept should be designed to put the toilet in a larger system, but the focus of the project should be on the toilet. The concept should be a draft of the service needed to support the product. The final concepts and the work will be evaluated at the end of the project.
A product concept of a urine separating boat toilet for a specific boat and usage including:
• Urine treatment unit that decreases volume adapted to the boat and the environment.
• How the feces are “flushed” in the toilet.
• Styling of the toilet.
• The parts and architecture of the toilet.
• How the toilet is emptied.
• Explanation of how the toilet is used, including things like flushing, changing of filter and emptying.
A simple draft of the supporting service of the toilet including:
• How it is connected to a waste recycling system.
• How consumables should be provided to the user.
Research questions: How would a Harvest Moon dry toilet work as a toilet for Swedish recreational craft users? How could a Harvest Moon dry boat toilet concept be designed?
1.3 Delimitations
• The project will focus on designing a product for Stockholm's archipelago. The participating users will be from this area, which represents the users.
• The toilet should be designed for sailing crafts.
• The concept should be a stationary toilet in the craft.
• The service will be limited to a sketch and to the users side and that which the user comes into contact with.
• Swedish users and toilet culture, which means users that sit on the toilet.
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1.4 Method
The thesis work will use a product design methodology which will be made up of four phases;
Planning, prestudy, concept development and concept presentation. This chapter describes the methodology in each of the phases.
1.4.1 Planning
The problem area was explored, the project defined, and different methodologies searched for. A work breakdown structure which is a method used to give an overview of the activities, sub activities and milestones of the project. It was performed by identifying and writing down all activities of the project, their sub activities and in which order they should be performed (Siami- Irdemoosa et al., 2015).
These were organized in a Gantt chart to illustrate the schedule of the project. A Gannt chart is a bar chart which lists the activities on the vertical axis and the time on the horizontal axis. The activities are shown as bars which width shows the duration of the activity (Clark, 1942).
1.4.2 Prestudy
During the prestudy phase, information and insights were gathered through different methods and analysed. The purpose was to get an overview and insights regarding the situation of today.
Two frames-of-references were researched to understand the purpose of the project and provide requirements for the concept. These were ecological sanitation as well as rules and regulations around sanitation in Sweden.
Research took place before and in parallel with the other activities as needed. To understand the technology behind the dry sanitation system, the experts at Harvest Moon was consulted. The current boat sanitation system and its infrastructure was investigated as well as the current boat toilets on the market and swedish recreational boat usage.
Ten interviews were conducted during the boat fair “Allt för sjön” with the present stakeholders, such as boat owners and different exhibitors. The interviews were semi-structured to allow the interviewees to talk freely but keep the topics to the relevant areas. The interview guides used can be found in Appendix A and the notes from the ten interviews can be found in Appendix B.
The analysis of the research focused on identifying user needs by writing down insights and categorise them. It identified different users and their specific needs.
The insights from the research was used to find a starting point for the concept development. The results of the prestudy were presented to Harvest Moon and together the user and technology for the project was identified. A requirement specification was written to direct the development of the proof of concept and help evaluate it.
1.4.3 Concept development
The concept development used an iterative design methodology which can be described by the basic design cycle model. It’s a model that describes the different phases when solving a design problem. The phases are, analyse, synthesise, simulate, evaluation and decision. In the analysis phase, aspects related to the design problem are analysed. In the synthesis phase, possible solutions are generated and in the simulate phase these are drawn and modeled to be able to evaluate the ideas. In the evaluation phase the ideas are evaluated and decided if they are acceptable or not in the decision phase. Then it goes back into the analyse phase. This cycle is repeated multiple times during the design process and the knowledge of the problem and concept increases with each iteration (Boeijen et al., 2017).
In this project most of the ideas will be generated through brainstorming and sketched, modeled or prototyped depending on which would provide the quickest results to evaluate. The evaluation will be done by looking at the requirements and in discussion with Harvest Moon.
4 1.4.4 Concept presentation
The proof-of-concept should serve as an inspiration for further work and should be communicated in a clear way. All the parts of the concept should be explained. It could include sketches, visual models, functional models of certain technological features, renderings, digital 3D models, flowcharts, journey maps or written scenarios. The methods should be chosen according to what best communicates certain parts of the concept.
The concept should be evaluated from the requirement specification and the user needs. It should discuss whether the purpose of the project was fulfilled and presented a solution to the problem.
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2 FRAME OF REFERENCE
Two frames of reference will be used as guidance to help keep the project focused. To give an insight to what dangers there is in sanitation as well as how an ecological sanitation is defined.
These were used as requirements in the requirements specification to make sure the concept follows current laws and regulations and work in an ecological sanitation system. One frame of references were added during the course of the project, human toilet related anatomy and waste.
2.1 Rules and regulations for human waste
Since human waste contains both nutrients and pathogens as well as potentially harmful substances, there is legislation to control the handling of it to prevent it from harming human health or the environment. Sweden’s national environmental legislation demands that any health or environmental impact is minimized to any reasonable extent. The municipalities are responsible for collecting most household waste, and any third party collectors must be employed by the municipalities unless special dispensation is granted. Each municipality must have a “Renhållningsordning” containing detailed regulations for the handling and collection of the waste that falls under municipal responsibility. (Miljöbalken kap 15)
Two example summaries of municipal regulations regarding latrine are given below.
In Stockholm, a facility without connection to the sewer system must either collect their latrine in a special 37 L container provided by the municipality’s waste handling company, or in a larger storage installation where it can be collected by the waste handling company. Private management of latrine through composting for nutrient recovery can be applied for, if it will be done in a suitable facility. The municipality can allow others to handle waste for special reasons, providing the handling is acceptable in health and environment aspects. (Renhållningsordning för Stockholms kommun, 2018:04)
In Norrtälje, a more rural municipality which includes the northern part of the Stockholm archipelago, regulations are similar, with the municipality providing and collecting 23 L latrine containers or emptying larger installations. The rules regarding composting and private waste handling are also very similar to Stockholm’s. However, the regulations allow and provide more detailed regulations for different kinds of local treatment facilities. (Renhållningsavdelningen på Norrtälje Kommun, 2016)
Waste rules for ships are regulated in Swedish law 1980:424, and waste from recreational crafts is more specifically regulated by chapter 11a of TSFS 2010:96. This law applies to all Swedish recreational crafts up to a certain size, and forbids any release of sewage into the water except for serious emergencies or accidents. An exception is made for pre-1965 vessels deemed culturally important, which may discharge sewage if they are at least half a nautical mile from the closest land. (Transportstyrelsen 2010) The Swedish Transport Agency may also allow exception if the sewage is treated on-board to such a degree that it can be released without inconvenience to human health or the environment. (Transportstyrelsen 2015)
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2.2 Ecological sanitation
Ecological sanitation is an approach created as a response to the future challenges in sanitation and agriculture. It treats human excrete as a resource rather than waste and sanitation as a part of a larger ecological system. It explains how to develop and implement eco-san approaches. It contains a number of criteria that should be met for a sanitation system to be sustainable:
• It must prevent disease by taking care of the pathogens in the feces
• It must prevent pollution and conserve water
• It must return nutrients to the soil
• It must be accessible to the world’s poorest people
• It must be aesthetically inoffensive and consistent with cultural and social values
• It must be robust enough to be easily maintained with the limitations of the local technical capacity, institutional framework and economic resources.
Ecological sanitation promotes understanding of sanitation as a system, where all components must be considered together when designing sanitation systems (Winblad, et al., 2004). This is the approach that Harvest Moon works with, closing the loop between sanitation and agriculture.
2.3 Human toilet related anatomy and waste
Vinnerås et al 2006 proposed new design values regarding Swedish household wastewater per person and year. A Swedish person produces 51 kg feces and 550 kg urine per year. This results in on average 140g feces and 1,5 litre urine per person per day. Feces are composed of 75 percent water and have roughly the same density as water. Urine is composed of 91-96 percent water. (Rose, C. et al., 2015)
The anatomy of the lower body of adult humans relating to toilets was illustrated in Kira’s book The Bathroom, see Figure 1 (Kira, 1976). It shows the distances of the anus, the male and female urethra as well as the location of the seat bones.
Figure 1. The anatomy of the lower body related to toilets.
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3 PRESTUDY
A prestudy was performed to gain an understanding of the current sanitation of swedish recreational craft, the products and technologies as well as the recreational craft users. Relevant websites and literature was studied and eleven interviews were performed with the user group at the fair Båtmässan in Stockholm. The insights gained from the study were clustered and categorised and the most relevant for this project is presented in this chapter. The insights and information found were analysed and the most relevant insights were used as a starting point for the development of the concept toilet.
The prestudy was divided in six categories, current recreational craft sanitation, state-of-the-art mobile toilets, about swedish recreational crafts, Harvest Moon technologies, the user and requirement specification. These are presented under separate headings in this chapter.
3.1 Current recreational craft sanitation
The literature regarding sanitation was found on the Swedish Transport Agency's website who has collected information regarding recreational crafts and the discharge ban. The rules of the ban can be found in the chapter about rules and regulations for human waste under Frame-of- reference.
The current boat sanitation faces a lot of problems according to the literature. The most usual boat toilet is the water toilet which stores the sewage in a septic tank and is emptied at reception facilities with the help of pump-out stations (Lagerqvist et al. 2016). Before the discharge ban the sewage was discharged directly into the water. Today, the users are required to empty their toilet waste at pump-out stations. These are often provided by the boat clubs or harbours and alternatively by the municipality. Many users are unsatisfied with the current system and the two largest problems for the users that were identified in the literature and interviews were:
• The onboard sewage capacity
• The reception facilities
A more detailed description of the identified problems can be seen in appendix C.
To understand the current sanitation system for recreational crafts in Sweden, the experts at Harvest Moon was consulted. The nutrient flow of the current system is linear, the nutrients aren’t returned to agriculture but instead incinerated or used as soil improvement. It can sometimes be used as manure for forestry, but the legislations are tightening. An illustration of the current system can be seen in Figure 2.
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Figure 2. An illustration on the flow of nutrients in the current sanitation system for recreational crafts.
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3.2 State-of-the-art mobile toilets
To understand the market and the competitors and their techniques, a state-of-the-art of mobile toilets was compiled. This would help to evaluate and understand the market and technologies.
Water toilets were the most frequent toilet, 6%, followed by portable toilets. There were also dry toilets and a small amount incineration toilets present. Among sailing crafts with a cabin 92 % had water toilets and 7% dry toilets (Lagerqvist et al. 2016).
Many different types of mobile toilets were found was divided into different types of toilets. This chapter gives a short explanation of each type of toilet. The study was done by Google searches on “båttoalett” “boat head” “boat toilet”, reading reports from the Swedish Transport Agency and tips from Harvest Moon.
Water toilets
Uses water to flush the sewage to a tank from which it can be emptied, usually by suction. The flush water can either be taken from the sea or from an onboard tank and the toilets usually use low amounts of water. They can be either electric or manually operated. They can be equipped with macerators or pumps that help dissolve the sewage in the water to avoid jamming in the pipes. A selection of water toilets can be seen in Figure 3.
Figure 3. From left to right; Jabsco manual toilet, Jabsco electric toilet, Dometic electric toilet
3.2.1 Portable toilets
Portable toilets uses water mixed with sanitation fluids to flush and stores the sewage in a tank.
A pump builds up pressure in the flush tank to help flush the toilet. They are emptied in a toilet or sink, some examples can be seen in Figure 4.
Figure 4. From left to right; Dometic portable toilet and two different Porta Potti models from Thetford
10 3.2.2 Desiccating toilet
A dry toilet which separated the urine from the feces. The feces are usually ventilated and mixed with an organic medium to help the dehydration. They usually have a way of mixing the feces with a crank. The urine is stored in a tank. Figure 5 shows some different desiccating toilets.
Figure 5. From left to right; Nature’s head, Air head, C-head and a DIY solution.
3.2.3 Composting toilet
A composting toilet composts the sewage and leaving a sanitised byproduct that can be added to the soil. They can be equipped with a heating element to help evaporate the liquids and are equipped with a ventilation fan and carbon-filters to remove the odour. Figure 6 shows a composting toilet for boats.
Figure 6. Sun-Mar mobile a composting toilet for boats and the mobile market.
11 3.2.4 Cassette toilets
A toilet where the sewage is stored in a removable cassette that is carried and emptied. It uses water to flush and comes with or without a separate flush water tank. Designed for mobile homes and can add sanitation fluids to reduce the odour. Figure 7 shows two different cassette toilets
Figure 7. To the left a cassette toilet from Dometic, to the right one from Thetford with the cassette.
3.2.5 Bag toilets
Bag toilets stores the sewage in a bag which can be compostable or not. The bag can also be used for flushing by moving it downwards and clam the bag. The bag can contain different additives for sanitation purpose and or solidify the waste. Bag toilets can be stationary or for portable use, see figure 8.
Figure 8. To the left, a stationary bag toilet from Pacto, to the right portable bag toilet.
3.2.6 Incineration toilets
Incineration toilets use gas or electricity to incinerate the sewage to ashes. They use a fan to remove any odours. The ashes are thrown away. Three examples can be seen in Figure 9.
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Figure 9. Three different incineration toilets.
3.2.7 Vacuum toilets
Vacuum toilets uses small amounts of water to flush. The vacuum transports and help dissolve the sewage. They also come with urine separation, see Figure 10.
Figure 10. A urine diverting vacuum toilet
3.2.8 Recirculating toilets
Designed for mobile homes, it uses water and sanitation fluids to flush the toilet. The sewage is filtered and the liquid is used to flush again. It only uses a single tank for the flushing liquid and sewage. See Figure 11
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Figure 11. A recirculating toilet for mobile homes.
3.3 Harvest Moon technologies
This chapter explains the technologies that are to be used in the project for the proof-of-concept.
3.3.1 Urine diverting unit
The urine is separated from the feces by a urine diverting unit. Harvest Moon had different prototypes of it, but they were not fully explored and designed because the seat which the unit is dependant on wasn't designed yet.
3.3.2 Handling of feces
The feces is stored in a container beneath the urine dividing unit. A flushing medium is added to the feces after each use to reduce the smell and help with the dehydration of the feces. The container is ventilated by a fan The commonly used water toilet, where water is added to flush and transport the sewage to the septic tank results in a quickly filled septic tank, which needs to be emptied before it can be used again. By reducing the volume of the sewage, the amount of sewage that can be stored is increased and results in less frequent emptying of the toilet.
3.3.3 Electronic control system
Harvest Moon have an electronic control system which controls the process. It can also be used to control electric motors and use data from many kinds of sensors.
3.3.4 Urine volume reduction technology
Harvest Moon has developed a technology for reducing the volume of the urine which will be used in this project. Due to Harvest Moons wishes to not have it published, any details will be left out of this report.
3.4 About Swedish recreational crafts
It was estimated in Båtlivsundersökningen 2015 that there are 756 500 seaworthy recreational crafts in Sweden of which six percent has a fixed toilet and four percent has a portable toilet. The most common fixed toilet is the water toilet which constitutes of 96 percent of the fixed toilets.
There are also four percent dry toilets and less than one percent incineration toilets (Lagerqvist et al. 2016).
Recreational crafts in Sweden can be separated into four groups, small crafts, day-trip crafts, motor crafts with cabin and sailing crafts with cabin (Lagerqvist et al. 2016).
The majority of the users prefer to use a toilet on land or in nature over using their toilet on the boat (Lagerqvist et al. 2016). This also came up during the performed interviews who said that they save the toilet for emergencies to avoid having to empty it.
Users with motor and sailing boats with a cabin spend most nights on the boat and use the boat for longer travels during the vacation. Main season for boats May-September. On average a sailing craft with cabin spends 16 nights per season and a motor craft with cabin 3,8 nights. The sailing craft also travels the longest distances (Lagerqvist et al. 2016).
The most nights stayed are at natural harbours followed by guest harbours. People are not generally satisfied by the possibility to empty their sewage at natural harbours. They are only marginally more satisfied by the possibility at guest harbours (Lagerqvist et al. 2016).
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3.5 User
From the information found regarding the user it was concluded that the user group that would benefit the most from a boat toilet with better capacity than the present toilets were identified as the sailors with sailing crafts with cabin. This was because;
• They travel for the longest periods of time and the longest distances
• It is more difficult to travel to reception facilities when sailing and using the motor destroys the feeling of sailing.
• Sailing provides a feeling of freedom and and always be able to use the toilet could be a part of this feeling.
• Sailing is to experience nature and not having to discharge the sewage into the water doesn’t have a negative impact on the nature.
• Sailing boats have more limitations than a motor craft and such a toilet would also fit a motor craft. Designing for extremes could provide solutions to the most problems with toilets and boats.
• Sailing craft users stay the most nights on the boat.
A larger sewage capacity would benefit those that spend longer periods of time on the sea without visiting many reception facilities. The project will focus on Stockholm’s archipelago because the largest amounts of sailing crafts is on the east coast. It is also were the project is taking place. It is assumed that the user needs are similar for all sailing craft users along the coasts of Sweden.
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3.6 Requirement specification
The most important information and insights from the prestudy was used to formulate a requirement specification for the concept design. The requirements can be seen in Table 1 and the wishes in Table 2.
Table 1. Requirements
Support 4 person (Average 3,3 persons on the boat)
Have a capacity for seven continuous days before having to be emptied
Follow the rules and regulations regarding handling of sewage as well as ecological sanitation guidelines.
Work during tilted craft
Fit the bathroom of a sailing craft Separate urine from feces
Low maintenance reception facility
Reduce the urine volume using Harvest Moons technology
Store the feces mixed with a flushing medium in a ventilated container Have a hatch for the feces storage to separate the feces from the user.
Table 2. Wishes
Have a capacity for 14 days including nights before having to be emptied Measure urine and feces levels in the system
Provide information regarding urine and feces levels Children should be able to use the toilet
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4 DESIGN PHASE
This chapter describes the design process of the proof-of-concept and the insights gained during the work. It describes the process in the order the work was performed and why it was done in this order. It also presents the most relevant results which affected the decisions and development.
The overarching design process was to first develop to most central components that other components were dependant on, followed by looking at the more peripheral components.
Between the development of each component, the architecture of the toilet were looked at to identify the next component to develop, as well as provide a general idea of how the concept were developing.
4.1 Technological feasibility
The urine treatment technology that would form one of the bases of the concept had to be evaluated in the boat environment because it had only been tested indoors. Harvest Moon did not want their urine technology published yet so the details is left out of this report. The boat environment was studied as well as the urine technology. The technology wes evaluated and was deemed feasible in the boat context.
4.2 Component overview
The main components that were needed for the toilet were:
• Urine diverting unit (UDU)
• Feces storage
• Urine tank
• Pump
• Urine treatment unit
• Control unit
• Fan
The UDU separates the urine from the feces. The feces falls into the feces storage which is ventilated by the fan and to which a flushing medium can be added. The urine is stored in a tank and moved to the urine treatment unit which reduces the volume of the urine. The control unit controls all electronics in the toilet. Figure 12 shows a simple chart of how the components are connected to each other and the different material flows through them.
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Figure 12. Illustration of the components and how they are connected.
4.3 Urine diverting unit and seat
Looking at all the different components that would be needed to design the concept, there’s one crucial part that control the design of the other components. That is the urine diverting unit (UDU), the component that keep the urine and feces separate. The UDU is closely connected to the seat, where the behind of the user will rest. Figure 13 shows two different kinds of UDUs on existing products.
Figure 13. To the left is Separett’s UDU and seat. To the right Nature’s heads UDU and seat.
There are several UDUs on the market, but most of these are based on the usual water toilet with a large opening. Boat toilets today have a smaller seat due to the lack of space on boats. Because the current solutions were found lacking, a development of a new kind of UDU and seat were developed.
An idea generation of problems with UDU in the context of boats were made and two main problem areas chosen with the help of Harvest Moon:
• How to make sure the urine and feces land in their separate places? This is about getting the user to sit correctly so the aim is correct.
• How large hole does the user need for the feces? The smaller hole, the smaller seat, the smaller toilet.
Because this was an ergonomics question, physical prototypes were made to find answers to these problem areas. This would help to get a feeling of the volume and usage and would provide imitate insights through quick testing.
4.3.1 UDU development
Harvest Moons prototype toilet that was shaped as a cube (principal sketch of the toilet) was used as a starting point for the development of the UDU and seat.
A prototype of the UDU and seat was built with the aim of being a flexible base for different tests. The feces hole size from one Harvest Moon prototypes was used as a starting point to explore different widths of the urine part of the UDU to see what would work. The thinnest which still felt like it could work was selected for testing. Figure 14 show the prototype.
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Figure 14. Two of the prototypes which tested the width of the urine part.
Some insights from these prototypes was that they felt uncomfortable, the genitals touched the divider between the feces hole and the urine part. A prototype UDU was developed in collaboration with Harvest Moon to make it easier to test different positions of the UDU in relation to the seat.
The UDU could be moved back and forth as well as up and down in the stool. With a lower UDU the problem with the genitals touching was solved, but it was difficult to sit on it. One of the seat bones kept falling down into the opening. Figure 15 shows different UDU positions.
Figure 15. Four different UDU positions with the collaboratively developed UDU.
This led to start the development of the seat.
4.3.2 Seat development
When seated on a normal water toilet, most of the weight is taken by the thighs and the buttocs hangs relatively free in the hole. This allows for many ways to sit, more to the front or to the back of the toilet. Because the feces and urine need to hit a specific area, such a solution would not be optimal, and it requires a large seat. Instead the focus was to look at a small hole and putting the weight on the seat bones or buttocs like sitting on a normal chair. A small hole would also provide more support area for the seat bones. Two pieces of foam were used to prototype a seat and tested, but it was difficult to aim, see Figure 16.
Figure 16. The simple foam seat prototype
The prototype was changed and angled foam pieces were added to help guide the buttocs correctly to the feces hole. They were made as thin pieces because it was interesting to know how large area the seat bones require to sit comfortably. It was installed on a water toilet and tested, see Figure 17.
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Figure 17. The second prototype on a water toilet
The main insights from the test:
• More difficult to wipe oneself on the prototype.
• You are unaccustomed to it, but you learn and get use to it with time.
• The buttocs need to be separate in order to defecate properly.
• The aim assistance works.
• Sitting on the seat bones feels more like sitting on a chair than a toilet.
• Having an angle smaller than 90 degrees between the thighs and upper body helped the defecation.
• The distance to the UDU is important as well as the size. You don’t want to feel like you touch the seat when wiping yourself.
Using a normal toilet the buttocs separate naturally when the whole behind is hanging inside the hole. The buttocs also start to separate when the hips are at the same height and lower than the knees. No problem to sit with small support. Toilet ergonomics was researched to gain information that could help in the development of the seat. This was added as a new frame of reference regarding humans and toilets and can be found in the frame of reference chapter.
To gain some new insights a step back was taken and different seats were tested. The prototype seat, a styrofoam seat with and without two different addons to reduce the size of the hole to match the UDU. These can be seen in Figure 18.
Figure 18. From left to right, prototype, styrofoam seat, styrofoam seat with half addon and styrofoam seat with full addon.
The next prototype had a feces hole large enough to allow the seat bones to be inside it and separate the buttocs. The next feature for the seat was the urine hole and was explored by incrementally increasing its size until the minimum size for it to function was found. Figure 19 shows the process of finding the right hole size.
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Figure 19. The initial prototype to the left and the final to the right with the steps in between.
The size of the urine hole increased until it was the width of a hand. This was in order to allow the user to be able to wipe their genitals or behind from the front. The size was also enough so that the user didn’t feel that their genitals was too close to the seat.
The hole had small rounded edges and didn’t provide the aim assistance that is needed for the defecation. Angled seat had proven to work before so different chamfers were tried, removing more and more until a satisfactory comfort and function was met. The seat would have a larger amount of chamfering around the feces hole because this helped guide the seat bones to the right position as well as help the separation of the buttocs. The back edge of the feces hole and the urine hole would have less chamfer and more of a rounded edge to help with the user feel were it was most comfortable to sit which is also the correct place to sit for a good aim. See Figure 20.
Figure 20. Inner hole edges
The design of the seat and UDU was stopped in order to have time to develop the other components. The insights from the development and the seat were used as a boase for Harvest Moons own UDU and seat design process.
21 4.3.3 Architecture
To get a better understanding of the volumes of the components a quick volume sketch was made using the largest components, the prototype seat, a stool, and two boxes to represent the urine tank and the feces storage. See Figure 21. The feces storage, needed to be developed. This was because it needed to be located underneath the feces hole to avoid having to transport the feces to another location. Feces are very sticky and therefore difficult to transport. By letting the feces fall straight down is the simplest solution and doesn’t need any parts that could malfunction. See Figure 21.
Figure 21. Quick volume sketch of one possible setup with the seat, feces storage and urine tank.
Some attempts were made to change the location of the components in relation to each other but the feces storage was the part that had the most questions surrounding it. Because the feces storages location was set, the only components that could have another position related to the seat, was the parts related to the urine treatment. It could easily be divided into two parts, the urine tank and the treatment because the urine can easily be transported with tubes and a pump.
Three compositional concepts were defined, one where all the different components were in the toilet. Another with the urine treatment separate and a third with the urine tank and treatment in a separate unit. These can be seen in Figure 22.
Figure 22. Different concepts of the setup with urine treatment unit (UTU), urine tank and feces storage.
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4.4 Feces storage
This chapter describes the process of the feces storage and the components that were closely connected to the feces such as the installation of the feces storage and flushing.
4.4.1 Top and hatch development
With the size of the feces hole determined, the development of the feces storage could be started.
The top and the hatch were the first things to start with because their sizes were defined by the feces hole and they also determines the size of the feces storage. The top also affects the feces hole of the shape of the UDU. The main function that was to be achieved is to have the feces enter the feces storage through the hole. The hole need to be as close to the user because the feces have a risk of leaving the body as a spray. This had to be balanced against having the dividing wall between the urine and feces part of the UDU as low as possible for leaving space for the users genitals.
• Feces hole as close to the user as possible/minimize the UDU area around the feces hole
• The dividing wall should be as low as possible
The requirements resulted in the top being angled instead of horizontal, see Figure 23.
Figure 23. Sketch of an angular hatch
Separett has made a urine diverting toilet which also has an angled hatch over the feces. When defecating people sometimes lean forwards, angeling behind backwards, resulting in the feces feces spraying backwards at an angle. The hatch could be curved instead of only angled which would minimize the UDU area around the hole even more. An idea generation of different hatches was made see Figure 24
Figure 24. Sketches of different hatches concepts.
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One hatch showed a lot of potential. It would allow for a curved top and take up a minimum of space when opened. A prototype of it was made to try it out which showed that it worked, but it also showed some problems. The prototype can be seen in Figure 25.
• Difficult to realise the opening/closing motion
• Difficult to manufacture
• Result in a large package when transporting
Figure 25. The prototype of the hatch with a curved top
The different hatch ideas were discussed with Harvest Moon who would prefer a robust and simple hatch. The curved hatch had a lot of potential so a quick solution for a curved hatch was prototyped, see Figure 26.
Figure 26. The prototype of a curved hatch that can be flat.
This prototype still suffered from the problem of how to realise the opening and closing motion and was discarded in favour for the revolving hatch which would be simpler and more robust.
The fact that it takes up more space when opened would not be a problem because the user would still need space to sit on the toilet.
The revolving hatch prototype was opened by pulling a string which extended a spring and closed by the spring when the string was released. Because the toilet already had a control unit an electric motor could be used to drive the hatch instead of mechanical means. This would result in a mechanically less complex concept. The hatch could be controlled by a sensor which registered when a person sat on the toilet. What type of sensor depends on the design of the rest of the concept.
The problem on how to drive the hatch by an electric motor was explored. It had to be a solution that would work with the cardboard hatch, a solution similar to the string was found, but instead of a string, a lever driven by a motor could pull the hatch open. This solution was further developed by looking at the transmission between the motor and lever as well as the lever and hatch. As well as how to install the hatch. These details have been left out of the report due to Harvest Moons wish to not have it published.
24 4.4.2 Feces storage development
Next was the storage that would hold the feces. Prototypes and concepts were made and evaluated with Harvest Moon. The details have been left out of the report due to Harvest Moons wish to not have it published.
4.4.3 Feces storage installation
An important aspect of the toilet usage was how the user would interact with the toilet. The user has to change the consumable feces storage which should be made simple. To access the feces storage the user would have to open the toilet. Different ways this could be done was ideated and a sketch of these can be seen in Figure 31.
Figure 31. Different ways to access the inside of the toilet
The size of the bathroom had to be considered, with the boats limited floor space. This excluded all movements sideways and left the ones moving upwards where there’s more room. The simple lid was found as the best solution because it could also help to hold the feces storage down from above. The user would lift the toilet seat with the UDU and see the insides from above. The feces storage would be lifted and installed from the top straight down. A rim and pins would lock the top of the feces storage from moving sideways, and the UDU lock it down when closed.
The user would also have to carry a used feces storage. To have handles integrated into the top of the storage or being able to lift and carry the storage in the thing its mounted into in the toilet was two ideas. Concepts for providing a barrier between the user and the used feces storages was ideated.
The last details of the feces storage would be the ventilation and flushing. It should have two holes that would align with the ventilation pipe and the flushing component.
A prototype of the feces storage setup was built of wood. It tested how the feces storage would be installed and also the lever drive solution for the hatch.
25 4.4.4 Flushing
The flushing of the toilet is the adding of powder or fine organic material to help dry out the feces. It will henceforth be referred to as flushing medium. This should be added on top of the feces and preferably cover them. An idea generation was made to find different ways to dose the flushing medium, the sketches of the ideas can be seen in Appendix D. It was complemented by research into different ways of dosing a set amount of powder by searching google and patent searches. Four problem areas with flushing were identified.
• Cover as much of the feces as possible
• Control the amount of flushing medium
• Where to position the flushing component in the toilet
• How the flushing should work
Different concepts of the flushing were developed and prototyped. The details of the flushing have been left out of the report due to Harvest Moons wish to not have it published.
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4.5 Urine treatment components development
The feces storage was developed enough to show that it would work as a concept. The urine part is the last undeveloped component to be able to put it together into a complete concept. Due to Harvest Moons desire to protect their urine technology the details of the developed urine treatment components will be left out of this thesis. A requirement specification was made in collaboration with Harvest Moon followed by idea generation and concept development.
Physical prototypes were made to explore the design and overviews of power consumption and flow rates calculations where done. A CAD model was produced.
4.6 Exploring the product architecture
Some sketches of the how the whole toilet could look were drawn to help come back to the overall architecture. Three different architectural concepts were found, the same as were found earlier. One were everything were in one toilet unit, one with the urine treatment unit separate and one with both the urine treatment unit and urine tank separated. The feces part is fixed where it is due to geometrical constraints and would require much mechanism to transport the feces which is difficult due to being sticky and we want hygiene. See Figure 38 for the three different architectural concepts.
Figure 38. The three concepts. From left to right: 1. All-in-one 2. separate urine treatment 3. Separate urine treatment and tank
Due to the limited space in a boat, the all-in-one concept was scrapped due to its size. The two other with separate urine treatment units, were chosen to continue developing. This because it could be placed higher up on a wall where there’s generally more space due to the shape of the boat. The concept with separated urine treatment unit and tank was scrapped because there are a lot room underneath the seat where the urine tank can be installed. This would reduce the size of the treatment unit as well as use some of the empty space inside the toilet. Before the choice was made the concepts were sketched to give a feeling of how they could look, see appendix E. The last component that needed finishing was the urine treatment unit.
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4.6 Final product architecture
The three concepts for product architecture was evaluated according to the limits of the boat.
Another visit to Allt för sjön was made to come back to the recreational craft scene and experience bathrooms on sailing crafts again. The all-in-one concept would be to large for the small floor area of the boats. The one with urine tank merged with the treatmentis not necessary because there are a lot of free space below the UDU where it can be and it makes no difference for the pump which has to move the urine up to the filter anyway. That left with one clear concept, where the urine treatment is separate from the urine tank and the toilet which are combined.
4.6.1 Air flow
To reduce bad smell and help dehydrate the feces, a fan is incorporated in the product and connected to an outlet.
4.6.2 Feces storage and flushing
The flushing component was finished by having it as a drawer on the side of the toilet, see Figure 40. Allowing it to be pulled out and refilled when needed. To communicate when it should be refilled, it should count the times it has flushed and after a set amount of flushes ask to be refilled. The number of times it can flush can be calculated by looking at the volume of the storage space for the flushing and the volume of the dosage for each flush. The specifics will not be calculated as the dosage of flushing medium needed for each flush is still being tested.
Figure 40. A sketch flushing medium storage as a drawer
These were modeled into the final concept of which a rendering can be seen in Figure 41.
Figure 41. A rendering of the final concepts CAD model
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4.7 Revisit Allt för sjön
The fair Allt för sjön was visited once more to reconnect to the recreational crafts after the component development. A seminar on “Regionalt planeringsunderlag för toalettavfall från fritidsbåtar i Stockholms län” was visited were they discussed problems with the sewage reception today and solutions for it. It showed that there are still many problems with today's system of water toilets. They had a project were they were using AIS (Automatic Identification System) to find the most frequently travelled routes to help plan where to place the reception facilities.
Sailing crafts and boat bathrooms were visited and pictures of them taken. A selection of these can be seen in appendix F.
4.8 Form
A form-proposition was made to show how the toilet could look with the concept components.
The form should keep a small footprint to allow it to fit into crafts with limited floor space. The purpose was to show how the proof-of-concept could look as a final product and to help understand the concept better in its context.
• Modern
• Fit into/borrow aesthetics of modern recreational crafts yachts.
A quick style-guide was made to help steer the design process to what it should express and preferred design features to help express it which can be seen in Appendix G. The methodology used was to encase the components in a shell, because unlike a flushing toilet it needed room for additional components. Rough sketches onto printed images of the CAD components served as a basis for the design and discussed with Harvest Moon. Quick 3D shells was drawn and rendered into a 3D mock-up boat bathroom to better understand the shape in the right environment. A final design was decided with Harvest Moon and drawn in more detailed.
The shape of the UDU was changed to the one Harvest Moon had designed after continuing my concept. Harvest Moon had also validated the UDU as prototypes.
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5 RESULTS
This chapter describes the resulting concept. It explains the different parts and components of the concept as well as renderings of the CAD model to show a possible styling of the concept..
5.1 CAD renderings
3D renderings of the CAD model was done in Keyshot. A selection of these can be seen in the figures in this chapter. Figure 42 shows a rendering of the concept in different colors.
Figure 42. Renderings of the toilet in three different colours.
Figure 43 shows how the flushing medium is to be accessed.
Figure 43. The opened flushing medium storage
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Figure 44 show how the toilet could look in a sailing craft’s bathroom.
Figure 44. The final concept rendered in a mockup boat bathroom.
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5.2 Architecture
This section describes the architecture of the concepts, where the different components are located and their volume in the toilet. Figure 45 shows the main components of the concept. The inside of the urine treatment unit is not shown due to Harvest Moons wishes to not show it. The fan is located at the end of the ventilation pipe.
Figure 45. The main components of the toilet
5.2.1 Information display
The product has a display which shows information regarding the status of the product and whether any actions need to be taken. Some examples of what i could show for the user:
• Off
• Ready to use
• Fill rate
• Change filter
• Change feces storage
• Refill flushing medium
• Error codes
The error code shows if the system has found a malfunction and will refer to the users manual for further instructions on how to remedy the error. The display is located on the door to the urine treatment unit. Because the unit would be located in the same room as the toilet due to the lack of space in the boat, it would be easy to spot for the user. The toilet could provide feedback to the user by playing sounds, such as the sound of a water toilet flushing to provide information that it has flushed for example.
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5.3 Usage
This chapter explains how the concept toilet is to be used.
5.3.1 Set up toilet
Open the toilets lids, fold out feces bag slide in the ventilation cardboard into the slider until stop. Align the top to the pins and push down. Close the seat lid, which holds the bag in place from the top. Slide open the flush compartment and fill with flushing medium. Make sure the arm of the hatch is added to the motor pin.
5.3.2 Using the toilet
Check the display to see if it’s ready to use. If all okay lift the lid and sit down. The feces hatch will open automatically when the user sits down. The urine flow down into the urine tank and the feces falls down into the feces storage. The toilet paper can either be thrown into the feces storage or into a separate bin beside the toilet. Having a separate bin increases the amount of feces that can be stored. The hatch will close as the user stands up and the flushing medium will be automatically added atop the feces. The user then cleanse the urine bowl using a spray bottle to flush any remaining urine to the urine tank. The flushing liquid reduces the smell and bacterial growth. It could also contain substances to add a nice scent to the toilet.
5.3.3 Changing the feces storage
The display shows when the feces storage needs to change. The two lids of the toilet is opened and the basket with the feces storages is lifted up. The plastic bag in the bottom is pulled up to cover the whole feces storage and can be tied together and stored in a can until it can be left at a reception facility. It can also be stored on the boat until it reaches a location where it can be handed in. A new feces bag can then be installed and the toilet can be used again.
5.3.4 Changing the urine filter
The display shows when the urine filter needs to change. The urine treatment unit is opened, the filtered removed and a new one is inserted in its place.
5.3.5 Refill flushing medium
Pull out the flush medium storage and pour in the medium up to the marking. Close it.
5.3.6 Service
The system developed in this project aims to close the loop of nutrients. The service to provide reception facilities to collect the waste will, same as today, be handled by boat clubs, harbours or municipalities. The waste from the reception facilities will be transported to an ecological post- production where urine will be transformed into fertilizer and feces will be composted.
The consumables used in the toilet could be delivered in flat packages as a subscription service.
Because the toilet uses electronics, it could be connected to the internet which would allow the toilet provider to collect data and plan the next shipment of consumables according to the usage.
They could also provide better assistance if the toilet malfunctions by looking at the information from the toilet. The user could use the same data in a phone application which tells the status of the toilet when not present. A problem is the network out on the sea which will limit these kind of functions to places with connection the network.
33 5.3.7 Reception facilities
There are different options to how a reception facility can be designed depending on how the municipality chooses to process the waste one concepts on how it could look like will be presented as an input to further work. Ordered in environmentally best and falling
1 Separate Feces and urine 2 Combined sewage 3 Normal burnable trash
Both the urine and feces can be burned, composted or added to the normal sewage stream, but in smaller doses or diluted to not disturb the treatment processes (Klingberg, J, 2017). They could also be shipped to Norrtälje wet compost sewage facility, which needs more dry components.
They are now adding animal sewage to the process to reduce the water content. The Urine can be used as a fertilizer because of the advantageous composition of nutrients for plants.
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5.3 Factors and insights related to toilet design
The purpose of the project was not to create insights and factors to consider when designing urine diverting toilets. But due to the lack of research in this area and that many findings were gained during the project, these findings were considered an important contribution to future development work. These are factors that are or could be interesting or relevant during design of urine diverting toilets. The insights have been collected in Table 3.
Table 3. Insights regarding urine diverting toilet seats
Feature of the seat
Insights
Feces hole • The closer the feces hole is to the user, the lower the chance of having the surrounding surfaces hit by the feces.
• Promote the separating of the buttocs by allowing space for the sit- bones, the user need separation to defecate properly.
• Allow for the user to wipe him or her both the rectum and urine hole.
• Children and different anatomics provides difficulties with aiming and correct seating.
Urine hole • Provide space for the genitals
• Provide space to experience that you have enough space (intimacy, hygiene)
• Allow for wiping of the urine hole
• Provide space for movements such as leaning and small movements without the genitals touching the seat
• Allow for wiping
• Allow for genital hygiene actions such as related to menopause The edge of the
seat towards the UDU
• Allow the sit-bones to be lowered
• Promote separation of the buttocs
• Provide aid with aiming (defecation mainly) and correct seating
• The weight should be on the thighs so that the sit-bones takes minimum weight and are allowed to hangs down into the hole Seat area (where
you sit) • Allow space for comfortable leaning on the seat to help with wiping oneself. At least 4 cm extra is needed on the sides for side wiping)
• Allow space for leaning forward for back wipe.
• Children have shorter thighs which must be taken into account.
Outer edge of the
seat • Make it comfortable to lean towards front and sides.
• Make it comfortable and easy to lean to the front for easier cleaning from the back
Size of the seat
hole • The larger the hole the larger the risk of feces ending up where they are not supposed to.
Children • Allow the child to sit far enough back so the feces falls down into the feces hole
• Children have shorter thighs which makes them sit closer to the front.
• A special seat for children could be placed on top of the seat to provide for them. This should preferably be developed at the same
