sign in sign up
<<
Home , Composting toilet

Composting : the basics Composting toilets come in as many shapes and sizes as those using them, as Liz Murdoch reports.

ll composting toilets Design types Treebogs are another simple design— decompose by creating There are hundreds of different and a personal favourite. A treebog is the aerobic (with oxygen) composting toilets, ranging from a form of composting which has conditionsA for , fungi, simple DIY designs to advanced high- willows and other nutrient-hungry worms and other macro and micro- tech commercial models. They can be plants planted around it. The term organisms to thrive. The objective classified as: was first coined by Jay Abrahams, is to destroy harmful , • Self-contained: where the toilet and founder of Biologic Design [1], after reduce the risk to human health and composting container are one unit. he noticed the vigorous growth of environment, and transform the waste • Remote: where the toilet is located willow trees around the pile nutrients into fertile soil. Composting separately from the composting site. of a bucket system toilet. Solid waste toilets typically break down waste to • Batch: where waste is collected and is held in a chamber open to the air ten per cent of the original volume. composted in two or more sealed which allows it to decompose rapidly, Most toilet composting systems containers, mounted on a rotating feeding the trees around it; liquid are low-temperature, known as carousel. When one container is full it drains away. Unlike a conventional mouldering toilets, but some are hot is replaced with an empty one. composting toilet, a treebog is usually (thermophilic). The waste material • Continual process: where waste not emptied or dug out when it must be heated to high enough is composted slowly in a single eventually fills up; the willows are temperatures that pathogens are container, and compost is harvested simply left to feed on the compost and destroyed, or left for long enough that from the bottom on an ongoing basis. the superstructure can be rebuilt or pathogens break down naturally. moved to an adjacent patch of ground Commercial models often have as necessary, and willow cuttings Compost that is too wet becomes advanced features, such as electric fan replanted [2]. Effectively, a treebog anaerobic (without oxygen) and ventilation systems, oxygen injections, converts human faeces to biomass. produces unpleasant odours. For or mechanical mixing and heaters this reason, some composting toilets to facilitate the fast Clivus Multrum is one of the more separate the urine from the faeces. of human excrement (good for cold popular commercial models, and The collected urine goes through a climates). However, there are also translates as ‘an inclining compost process of nitrification, resulting in an low-tech models that use passive room’ if you know Latin and Swedish. odourless, bacteria-free liquid that can ventilation systems to prevent odours, This design utilises a two-level be used as a fertiliser or leached safely passive solar design to heat the container connected to the toilet into the ground. Other models collect compost, and turning by hand to with a variable chute. The unit has an urine and faeces together, and either increase aeration. inclined base where solid waste slowly evaporate the liquid off completely or decomposes (over two years) and slides require the addition of carbon material Bucket systems are the simplest and down to the lower level. Excess liquid such as , leaf mould, straw or cheapest type of composting toilet, is drained to the lowest part of the grass clippings to soak up the liquid. with a bucket placed under the toilet container, and collected or evaporated. seat, the contents of which are kept covered at all times with clean organic Whatever type you go for, good toilet Above, left to right: Liz’s treebog at Keil near carbon material to prevent odours, design includes planning for the Appin; A detail of the door at the composting toilet at Drumdreel on Falkland Estate. absorb urine and deter flies. When future, including who will maintain Photos: Liz Murdoch. the bucket is full it is deposited onto it and when, their commitment level an outdoor compost pile. and knowledge base, and whether www.reforestingscotland.org ISSUE 60 Reforesting Scotland AUTUMN/WINTER 2019 p23 Appropriate technology

they know where and how to start a safely-maintained composting site. Another design tip is to ensure that First, produce no waste! the user cannot see the contents of a composting toilet, which should be There is a process to choosing the right design out of view, a metre or so below the platform, and in dark shadow. of composting toilet, as Jude Dunn explains. Sustainable hen I arrived to live on amazing view over the farm from aloft All composting toilets require some my plot in Wales with a on the loo! Recommended. form of management to ensure that caravan, the first thing was they remain clean, hygienic and odour toW get drinking water piped in, and On a small holding in free. And all but treebogs need to the second was to build a composting Portugal, a stand-alone toilet included have compost material removed at toilet. The toilet was built in October toilet plus wood-burning water heater regular intervals. But these are minor 2010 and is still in use today. I used with shower and sink. Built on a steep inconveniences compared to the a design process I learned from slope, on a terrace path, the slope advantages of composting toilets. They permaculture with the acronym was used to create the required drop protect , surface water and SADIMET, which stands for: survey, to the collection chambers, made soil from , prevent the analyse, design, implement, maintain, easily accessible for emptying. The accumulation of hazardous pathogenic evaluate, tweak. toilet was a dry, solids only; no steps waste, and solve the problem of were involved for access. Tiled inside disposing to . My site is generally level, suffers and lit with a solar sensor light, it They save huge quantities of water in sometimes from high winds and is has beauty too. A second structure at a world where water is an increasingly often extremely wet, having flooded another off-grid holding in Portugal, scarce resource, and require very little in the past. In addition to considering was timber built, unlit and rustic, infrastructure. They are low-impact, shelter, accessibility and the also using a slope to create the drop. low-maintenance and can be adapted neighbours downhill, I also wanted This was also dry, solids only, with a to any situation, even in places where a loo with a view and it had to be separate area with wooden planks to it is difficult or inappropriate to mobile. stand on to squat to wee. It was not establish a mains toilet system such always so inviting to use, especially at as hard rocky soils, high water tables, To understand the composting night in darkness with a severe drop near springs or in an environmentally- process, The Humanure Handbook is behind! sensitive area. a must-read for anyone setting out on this venture. First published in Leeds Eco houses have the most Composting toilets are an excellent 1995 as a graduate school thesis, with impressive composting toilet I example of . They a print run of 600 copies, it turned experienced, built within a two-storey provide a safe and effective way into an underground best-seller. The house, upstairs with a long drop (with to reduce resources and prevent author of this self-published book protective bars) to a chamber beneath pollution, whilst saving money and expected to watch it decompose in the Walter Segal design foundation- energy for the household and the his garage for the rest of his life. Yet, less house. This is not a separating community. At the same time they the fourth edition came out in May loo, taking both solids and liquid, produce a valuable end-product 2019 and the book has sold 70,000 and did not smell—it’s place was in that can be used to fertilise the soil. print copies in the US alone, been a next to a bath. Sawdust Once these remarkable benefits are translated in whole or in part into 19 from deciduous trees and dry leaves understood they are likely to become languages and has been published in are used as ‘flush’. This provides a even more popular. The photos above foreign editions on four continents. great example of a composting toilet are of my treebog on Keil Hill, which And it is available to read online [1]. in a city context. was finished in 2011 and is still a very pleasant place to retire to. Survey Dan’s treebog in Scotland is built on Composting toilets can be temporary flat ground on a Highland croft and Reference or permanent, and are more versatile uses strawbales and chicken wire to 1. biologicdesign.co.uk than many would think—people ensure it is rat-proof. Steps up to the 2. permaculture.fandom.com/wiki/ are fascinated by them. I surveyed a loo provide the required drop; it is a Tree_bog variety of composting toilets, some of substantial and private toilet. There which feature below. are some really lovely features with Liz Murdoch has been surveying the carved closing handles. On a site literature on composting toilets for Ragman’s Lane loo in Gloucestershire prone to high winds, the loo helps many years and is indebted to pioneers is on the outside of an existing shelter beehives behind it, and the tall such as permaculturalist Jay Abrahams, building and high up to make use of toilet structure itself is sheltered on and Joseph Jenkins, author of The the drop, is solids only, and used a one side by spruce woodland and on Humanure Handbook. If you are mesh-protected pipe for smell and fly the other, by a log cabin. interested in how to build a treebog, Liz control; is a , using sawdust is happy to send more information. E: as ‘flush’. In the campsite a series Elsewhere in Scotland, in Argyll and [email protected]. of composting toilets provide an Bute, there is an A-frame wilderness p24 ISSUE 60 Reforesting Scotland AUTUMN/WINTER 2019 www.reforestingscotland.org Appropriate technology

and staples. I kept the cost now dry, contents of the wheelie down by acquiring a reclaimed bin in a one-metre by one-metre door, water butt, sink, and compost bin. The other maintenance windows; a tap, connector and task is collecting material for flush: pipe I had lying around from dry leaves, sawdust and ash. Wind- other jobs. proofing has proved essential with a small, yet tall, structure and more Having been on a Walter Segal extreme weather events. I use ballast four-day building course at inside during winter—drying logs the Big Tent in Fife, in 2006, and have even used stones—and I I put these skills to use. Segal have put bracing on the back against buildings are raised above the the prevailing wind. ground on legs, which would provide the height needed to There has been a continual cycle use a wheelie bin container. of maintenance, evaluation and I decided to separate and to tweaking. The first tweak was to add use urine elsewhere in other a barrel of water and connect that to systems. To flush I use dried a small sink. A porch would provide leaves, chopped straw, wood better weather protection at the door. ash and hardwood sawdust The secondary composting system with some to takes another year to process before enhance the composting its dug out and put on perennial fruit process. Putting human solid bushes; such compost is not generally waste into water immediately recommended for annual vegetables. I toilet, built in relative isolation, loses the good bacteria, which have used straw bales for taking urine on a nature reserve/community otherwise fuel the composting before composting and plan to find a woodland in a robust and impressive process. Rainwater I harvest from better way to use urine. timber A-frame building. This loo the roof, store in a barrel for hand is substantial, close to the source of washing, which also acts as a back-up I have ideas about using the toilet to the building materials. Rainwater for the garden. inform people about global is collected for hand-washing and issues, water issues and language clear instructions mean all visitors The design allows use of the toilet for use around dealing with our shit can read how the system works. several functions other than providing and, therefore, our health and the There are two alternating chambers, compost, including as a wood store potential health of soil. Visiting the so that when one is full it is closed for seasoning logs, growing some loo is a good time to muse. Changing and the toilet moves to the other, plants for , and the the language around how we view while the composting process reaches opportunities to experiment with a our waste might help create better completion in the ‘resting’ chamber, composting system. Toilet paper is solutions, as would understanding it which can be emptied in time for the one input involving cash so I have as part of a natural process that can be the active one to be closed and rested grown lavataria and plan to grow cleanly and productively dealt with. I when full. mullein close by to use instead. would like people to understand their potential as walking plant fertilisers Implementation I pushed the Walter Segal design as and soil builders. Armed with this survey information, far as I could but diagonal bracing I considered my needs, wants and was needed to provide strength as I According to Waterwise, there are resources. As my site had previously did not use plywood on the inside to about 45 million toilets in the UK, flooded and my neighbours’ family provide internal structural tension as which means two billion litres of were close and downhill from me, I is required by this form of building. water are flushed and wasted every wanted a ‘closed’ system that could The frames were ideal to create the day. A third of our good drinking not be flooded. The site was mainly floor and internal shelving. Once the water goes down the toilet where it is flat so I needed a structure where frames were in place and braced by polluted and then we spend money height would provide the possibility the floor, the external cladding was cleaning it again. If everyone used of using a collection container. I fastened and my volunteers provided a waterless toilet that problem is wanted the outputs to be part of a some creative flourishes. immediately cut by 30 per cent. soil fertility system so I needed the resulting compost to be easy to move. Maintenance References Other needs were to be rodent-proof Maintenance consists of exchanging 1. humanurehandbook.com/contents. and affordable. My chosen design cost the current wheelie bin with an html £209, including timber, a wheelie empty one, screwing down the lid and bin (to collect the waste), a loo seat, letting it stand for a year or so. After Jude Dunn lives on a low-impact corrugated plastic for the roof, a food a year, I empty the collecting bin holding in Wales but is looking to return container for flushing material, screws and create a secondary composting to Scotland and set up a small land- system: layering up green waste from based business to support . Ragman’s Lane loo in Gloucestershire. Photo: Ragmans.co.uk. the garden and straw with the, by E: [email protected]. www.reforestingscotland.org ISSUE 60 Reforesting Scotland AUTUMN/WINTER 2019 p25 Appropriate technology PeePower®: a light bulb moment Human urine can light our futures, as Dr. Pavlina Theodosiou and Prof. Ioannis Ieropoulos explain. ot a day, not a moment that microbes can break down to After a successful trial, the was goes by that we don’t use release electrons which are harvested scaled up and tested at Glastonbury electricity. It has become part in MFCs and turned into electricity. festival in 2015 and 2016, Nand parcel of our life, from lighting The microbes responsible for this accommodating 20 people at one homes and cooling food to powering valuable transformation are naturally time. The collected urine powered the up smartphone batteries and charging occurring, which makes this technology internal night time lighting of the urinal electric vehicles. However, the constant affordable and applicable anywhere in for the duration of the festival. Bigger demand for electricity has had a the world. Since its discovery by M.C. and better PeePower® returned devastating impact on our environment Potter in 1911, this technology has to Glastonbury in 2017 and 2019. causing global warming and fossil only been documented in laboratory- The most recent model accommodated fuel depletion. Finding alternative scale experiments—until recently. 40 people, and continuously powered sources, affordable Since 2002, researchers at the Bristol the internal lights, as well as lit signs, and accessible to all, is now gaming devices and the paramount. hardware to maintain system operation. The urinal Over the past few years, a attracted more than 5,000 large number of alternative people and when asked, 92 energy sources have made per cent of them stated that it possible to start reducing using the system had given our reliance on fossil fuels. them more confidence in Energy providers in the . UK now offer 100 per cent green energy options More than a billion people to their customers, and live without access to energy technologies such electricity and hundreds as photo voltaics and wind of millions more live with turbines are commonplace. unreliable and expensive However, there is another power. PeePower® has been sustainable technology successfully installed and which appeared at the operated in Uganda (Seseme beginning of the last Girls School), Kenya century, but has seen (Brainhouse Academy) and an exponential rate of South Africa (Thandanani advancement since the Township). Our aim at the mid-2000s. This technology is called Bioenergy Centre at the University of Bristol Bioenergy Centre is to develop Microbial Fuel Cell (MFC) and it the West of (UWE), Bristol this technology, making it available generates electricity using microbes that have been developing this technology globally, providing access to electricity can consume the found for real-world applications. The and improving sanitation. What could in waste liquid. Recently, we discovered most notable example is PeePower®, be more appropriate? that one of the better fuels for this a product that can turn urine into technology is something that each of us sufficient electricity to power lighting robial.org excretes several times a day—urine! or charge mobile phones. Initially this product was trialled in 2015 at UWE Dr. Pavlina Theodosiou is Research We flush urine down the toilet and yet Frenchay Campus in a collaboration Associate at the Bristol Bioenergy Centre it is a powerful, nutient-rich resource with OXFAM, in an attempt to test a (BBiC) in Bristol Robotics Laboratory real-life urinal cubicle similar to those (BRL) and Prof. Ioannis Ieropoulos is Above: A Microbial Fuel Cell has two electrodes used in refugee camps. The aim of this the director of the BBiC. The PeePower® separated by a membrane. Bacteria are trial was to test whether the system technology is in the process of becoming inoculated into the (negative) anode and left to could power lighting inside the urinal commercially available through a new grow. As they metabolise the urine provided, the bacteria release electrons which travel through structure using only the urine produced company, Robial. The Urinetricity project the circuit. Bacterial metabolism also releases by the users. Such an application is and PeePower® technology could not have positively charged cations, such as protons that extremely important in refugee camps been successful without the funding and move through the membrane to the (positive) and slums for lighting up often dark support from the Bill & Melinda Gates cathode, where they recombine with oxygen and dangerous places, providing safety Foundation, EPSRC, the European and incoming electrons, producing water. MFCs, unlike a battery, can produce electricity particularly for women. Commission and OXFAM. indefinitely as long as they are provided with fuel. p26 ISSUE 60 Reforesting Scotland AUTUMN/WINTER 2019 www.reforestingscotland.org