Waste Management on live-aboard Boats: The Environmental Impact of Composting Toilets in the UK
This blog is formed from work I undertook as part of an MSc in Environmental Management from the University of Derby from 2016-2019. This website serves as a repository for this work.
The following work was written in 2018
Canal-boaters are, by their nature, off-grid and so require unique solutions to the issue of dealing with toilet waste while afloat. Recently composting toilets have risen in prominence within the boating community.
This research paper aims to highlight the impact of this toilet technology by comparing their use against the EU Waste Hierarchy, and by using the three pillars of sustainability as a roadmap. The research was carried out mostly through literary sources, however informal interviews with canal-boaters were also conducted.
The main findings of this paper are as follows:
• CTs provide a convenient solution to dealing with human waste aboard a canal-boat, however due to a lack of specific disposal options available, the waste is usually disposed of using unideal methods.
• There is an unwillingness amongst boat users to install CTs, despite the loyal following they enjoy. This is largely due to unfamiliarity with the technology and a perception of them being unhygienic.
• The potential for waste from CTs to be processed more efficiently is great, as the current disposal methods risk becoming a larger environmental issue if the improvement of infrastructure doesn’t match greater uptake.
Introduction
The three common options for boat toilets are:
1. Electric or manual pump-action toilets, utilising a water flush and a storage tank.
2. Chemical (Elsan) toilets with manual waste disposal, where human waste is passed into a receptacle filled with chemicals that neutralise bacteria, microorganisms and odour (Elsan, 2018).
3. Composting toilets (CTs), where human waste is collected in a receptacle in a way that aids aerobic decomposition and acts as a first stage of the composting process (Canal & Rivers Trust, 2017).
In comparison to conventional boat sewerage systems, CTs avoid water consumption and require less electrical energy than modern electric-flush boat toilets (Sail Magazine, 2015). Furthermore, manual waste disposal requires no extra infrastructure, such as toilet tank pump-out facilities and black water storage tanks (Whilton Marina, 2015).
Whereas chemical systems appear superior to CTs in avoiding any kind of electricity use (some CT systems are run with an electric fan to ensure air flow and to avoid anaerobic growth within the receptacle (Porto & Steinfeld, 1999)), chemical toilets require a specified container for appropriate storage of the used Elsan solution, risking improper disposal e.g. by introducing the solution into the conventional waste water systems (Sail Magazine, 2015). CTs make use of the conventional waste disposal facilities and thus facilitate adherence to proper disposal routines (Guardian, 2014; Porto & Steinfeld, 1999).
The proposed research looks at CTs and their environmental impact overall, using the framework of the 3 pillars of sustainability (Kuhlman & Farrington, 2010). To this end, theMain Research Question will address the overall impact, whereas the Sub-questions will elucidate an aspect of each of the 3 pillars. The findings of the research will be assessed and condensed, using the EU Waste Hierarchy (EU, 2010) as a guiding principle.
Table 1: Materials and Methods
As shown in Table 1, the Main Research Question (MRQ) addresses the overall environmental impact of CTs in a live-aboard boat context. Utilising the 3 pillars of sustainability, the MRQ has been broken down into 3 Sub-Questions (SQ) as shown, each addressing a different pillar.
To answer SQ 1, literature was used in order to provide as wide a scope of data as available. As there is little academic writing on the subject, literature from popular sources, such as blogs, websites and magazines aimed at the live-aboard boating community as a main audience, was also used. Sources mentioning CTs in other contexts, such as in tiny houses or camper vans, were used if no specific literature pertaining to their marine use could be found. Using the idea of expert panels as a guiding principle (Wang, 2015), several boaters were contacted in order to provide their view on different marine toilet technology.
Whereas the information gathered is of a unique value to explore especially the social pillar, various limitations must be mentioned: The expert panel included two remote participants (via Facebook) and four discussion participants on location, whose opinions and ideas may also be partly shaped by their previous experience with different technologies in other contexts.
Although a targeted question was posed during the interview, this aspect cannot be fully eliminated and may influence the validity of the data (Wang, 2015). Furthermore, the sample included two female and four male participants. As is shown in theory about the general use of new technology (Venkatesh, et al., 2016), gender may play a determining role in how technology is approached. More practically, women’s use of a composting toilet also differs from that of men (Porto & Steinfeld, 1999).
Lastly, boat technology may not necessarily be the individual choice of the current owner, but may be determined by technology already on board when the vessel was purchased (Canal & Rivers Trust, 2017). SQ 2 was researched through Facebook conversations with prominent members of the boating community.
Additional data was gathered by conducting a semi-structured group interview with live-aboard boaters on location in the UK. As SQ 3 addresses both overall deliberations as well as personal experiences, both literature sources as outlined for SQ 1 as well as boaters’ personal opinions and ideas were included.
The findings are presented for each SQ, and overall conclusions are drawn in the discussion; highlighting how all SQs overlap and correlate to answer the main question. To focus the different data gathered through literature study and interviews, the EU Waste Hierarchy (EUWH) is used as a conceptual lens in order to guide the conclusions drawn. The framework was introduced in 2008/98/EC and visualises the guidelines with regards to prioritising different waste management objectives.
Results and Discussion
The Environmental Impact of Composting Toilets – Sub-question 1
As outlined in the Introduction, CTs are environmentally efficient in their avoidance of water waste and chemical use, as well as their low-energy impact. These aspects all fit the highest structure of the EU Waste Hierarchy (EUWH) in preventing these resources from being used in the first place (EU, 2010).
Whereas the non-reliance on existing specialised infrastructure on the one hand involves another aspect of prevention in avoiding the use of resources in producing and maintaining said infrastructure, this aspect warrants a closer look with regards to the EUWH. While there is no formally indicated way of disposing of composted human waste,the anecdotal evidence shows that waste is either buried along the canal-side or is included in mixed household waste (ThisNarrowBoatAdventure, 2016) (Lilo, 2007).
Both options have an environmental impact. In regards to the EUWH, the burial/spreading around vegetation option directly re-uses human waste (Level 2 of EUWH). However, this bring up its own set of environmental issues, such as the introduction of possibly biohazardous materials into the landscape (Ells & Monz, 2011) (Pearce, 2013)
If composted human waste is included into mixed household waste, it is transferred down to Level 4 and processed along other non-recyclables. If the waste had been added to a specific sewage stream system, it would have most likely been included in digestion and have offered some energy recovery. Whereas this still put it on Level 4, it would still offer benefits over incineration (Cofie, et al., 2009) (Jouhara, et al., 2017) (Chirjiv & Defne, 2014)
During the discussion with boaters, it was confirmed that most users of CTs revert to a mixture of burial and inclusion in household waste, with burial an occasional option in rural areas where the canal side vegetation is not on private land or agriculturally used, and inclusion in household waste whilst moored in cities or locations where burial is not an option due to the urban setting/lack of access to vegetation. Boaters also mentioned that many users of CTs find the burial option too confronting, are unsure about remaining biohazards or worry about effects on the local groundwater and therefore prefer the inclusion in household waste as a ‘safer’ option.
The Social Impact of Composting Toilets – Sub-question 2
In addition to the environmental aspects mentioned above, the research participants enumerated a variety of points that specifically highlight the social impact of CTs. All interviewees agreed that CTs are a somewhat divisive issue, with many boaters seeing them as unclean or unhygienic.
Without direct personal experience, it was recounted that many boaters assume CTs to be associated with unpleasant odours and therefore perceive them as a somewhat primitive technology.Two participants recalled their own and the experience of friends who own CTs on their boats, stressing that visitors who are unfamiliar with boating technology may be quite resistant to make use of a CT due to the aforementioned stereotypes. Both CT owners specifically mentioned feelings of guilt with regards to spreading composted human waste on towpaths and other canal side environments which the public also uses frequently, particularly in less rural areas where people have access to the canal side for recreational activities, e.g. through waterside hiking paths.
One boater also told of her experience when purchasing her vessel from a boat broker, saying that, when discussing improvements planned to the boat prior to purchase, the broker was very reluctant to even consider her preferred inclusion of a CT as a viable option. In her opinion, the idea of a CT on board was very clearly communicated as a ‘fringe’ solution, with the broker also indicating that the absence of a chemical or pump-out system might jeopardise the boater’s potential success if she ever were to resell her vessel.
Both CT owners said that, whilst they would try and encourage a potential future purchaser to consider the CT as a working system, they were prepared to include either a chemical or pump-out system to ensure the resale value of their vessels. Again, this was attributed to the reluctance with which the boating community has responded to the technology.
Interestingly, one boater who currently uses a pump-out reported that he had briefly considered a CT, but had been discouraged by his female partner. In his opinion, women might be less inclined to consider CTs, especially during their menstrual periods, as the lack of a flush may suggest a lack of hygiene. Interestingly, both users of CTs included in the expert panel were female and indicated that they found this not to be the case, however, this would need to be investigated within a wider study to elucidate whether indeed women view CTs differently.
The Economic Impact of Composting Toilets – Sub-question 3
AcquisitionIn terms of acquisition cost, chemical systems are the cheapest option, with a mid-range chemical toilet available for around £500. In comparison, a mid-range composting toilet is priced at around £1000; pump-out systems cost around £1200 for the tank and toilet. With the latter, costs for installation and the remodelling of existing structures to accommodate the new system has not yet been included, as this varies considerably from boat to boat (Canal & Rivers Trust, 2017) (Whilton Marina, 2015).
Running Costs & Consumables
All systems use minimal electricity for fans, pumps and flushes where applicable. Whereas chemical systems and CTs both use consumables in the form of chemical solutions/bedding material, pump-out systems incur regular costs for emptying of the sewage tank (Whilton Marina, 2015).
This equation is based on purchasing bedding material for CTs, however, the system is also workable with any dry natural material, e.g. sawdust, shredded paper, wood chips or coconut fibre. Both boaters interviewed reported at times being able to acquire bedding materials free of charge from e.g. local sawmills, thus avoiding all additional costs.
However, what sets CTs apart in terms of running costs is their comparative simplicity: Whereas chemical toilets use cassettes with multiple parts that will require maintenance/replacement (Lilo, 2007), pump-out systems may also necessitate the skilled labour of a plumber/technician to address any problems that may occur with the system (Whilton Marina, 2015). CTs provide a comparatively simple system with few intricate parts, allowing for easy maintenance by their user and largely avoiding additional costs for repairs to the system.
Conclusions or Implications
Looking at SQ 3, CTs have been shown as an economically viable option, whose slightly higher acquisition costs are offset by low maintenance costs and longevity due to the simplicity of the system. As CTs use no water and very little electricity in their running, their day-to-day use complies with the highest level of the EUWH in avoiding the use of resources (EU, 2010) (Porto & Steinfeld, 1999).As such, their use should rightly be promoted to the boating community as a cost- and energy effective waste management solution.
The responses in SQ 2 have indicated potential obstacles that may need to be overcome in this process, namely overwhelmingly negative attitudes towards CTs and prejudice with regards to their convenience and hygiene. This may be overcome by encouraging manufacturers of CTs to allow potential users a ‘direct’ experience, e.g. through exhibitions where the technology may be seen in use. Manufacturers of CTs may also consider trying to place their products in public bathrooms, thereby encouraging a new experience of CTs that may sway negative perceptions.
Further, the recounted experience of boaters that brokers may discourage purchasers of vessels from considering CTs may stem from the fact that brokers often offer services such as the installation of sewage tanks and pump-out marine toilets (SQ 2). This allows for the conclusion that brokers argue with a view to maximise own profit. Purchasers may need to be encouraged to be critical consumers, e.g. through information about CTs that is easily accessible through boaters’ communities, relevant literature and social media.
SQ 1 has provided insight into the fact that, if composted human waste is deposited by burial in the appropriate environment, the use of CTs is placed at Level 2 of the EUWH in re-using the waste product directly without requiring processing or waste management.
However, it was shown that the disposal of composted human waste as collected in CTs within regular household waste drastically heightens its reliance on waste management systems, relegating it to a mere Level 4. At this level, composted human waste requires energy-intensive processes such as incineration, albeit offering some pay-off effects in recovering and harnessing some of the heat energy from the process.
Encouraging a disposal method that remains in the desired, higher Levels of the EUWH may partly depend on the education of the individual user, e.g. by offering information about the safety and appropriateness of spreading composted human waste on the landscape.
However, given that boaters report hesitance with regards to doing so, the disposal of composted human waste in a separate receptacle to allow for a discrete waste stream apart from general household waste may provide a viable solution. Human wastebins could be introduced to mooring spots/marinas, similarly to dog waste bins, and offer collection points that allow for the waste to be treated as a single waste stream.
Acknowledgements
Interviewees:
Elizabeth Currie, Charles Evans, Alan Gregory, Martin Hanson, Dominic Murphy, Mary White, Facebook Contacts (Youtube boaters)
Cruising the Cut, Journey with Jono, This Narrowboat Adventure
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