Ecological Sanitation Some low cost methods of recycling human excreta Peter Morgan 2004
Recycling nutrients from human Being able to recycle nutrients held in human excreta is one of the most important benefits of ecological sanitation. There are many ways of doing it. This lecture describes three simple and basic methods of recycling human excreta. excreta
3 basic methods of recycling nutrients 1- Growing trees in shallow latrine pits 2 Making humus by combining excreta with soil, wood ash and leaves in: Shallow latrine pits & Urine diversion secondary composting sites 3 Using urine as a plant liquid feed
Method one - plant a tree! Trees will grow in composted human excreta. They will even grow in well composted deep pit latrine humus But trees grow better if the pit contents are a mix of excreta, soil, leaves and wood ash.
The Arborloo The eco -toilet that becomes a tree! This is the simplest eco-toilet It is a pit latrine mounted over a shallow pit A mix of excreta, soil, ash and leaves are added to the pit during use Once nearly full the structure and concrete cover slab are moved to a new pit site The near full pit is topped up with a layer of top soil and a young tree is planted in the soil, protected and watered.
Recycling nutrients into trees
Trees growing on Arborloo pits For much of Africa, the Arborloo is an excellent entry point for eco-san. A wide variety of trees will grow on a richly organic pit. These include banana, paw paw,, avocado, mulberry, mango & guava. Gum trees and Cedrela are particularly hardy. Indigenous trees like Brachystegia and Acacia also grow well.
The Arborloo can be made very cheaply. All that is required to start is a simple concrete slab mounted on a ring beam made of bricks or concrete. One metre diameter slabs can be made with as little as one eighth of a bag or cement (5 litres cement mixed with 30 litres clean river sand). A concrete ring beam uses the same amount of materials. The shallow pit is dug within the ring beam and the slab s mounted on top, with a suitable structure of local materials built for privacy. Leaves are added to the new pit and then excreta together er with soil, ash and leaves through the life of the toilet.
The low cost Arborloo The method of making the slab and ring beam is simple for villagers to undertake with basic training. It is important to keep the newly made concrete slab wet after hardening for ten days to cure properly. Once the concrete slab is fitted, any type of suitable house can be built on top for privacy. Once full of the mix of excreta, soil, ash and leaves, the slab, ring beam and house are moved to a new location and a young tree planted on a deep layer of soil placed over the pit contents.
Arborloo s built in Malawi There is infinite variation in the way the Arborloos can be built. Also many types of fruit tree can be grown. Paw paw and banana are very popular. Passion fruit also grows well on the Arborloo pit.
Method two make humus Fertile humus can be made in shallow pits by adding a mix of soil and wood ash to the excreta. It can also be made by combining faeces with top soil and wood ash in secondary composting sites linked to urine diverting toilets such as jars or shallow pits. In both cases the texture of the final product is greatly improved by adding leaves. This humus is rich in nutrients, and when mixed with poor top soil can greatly enhance vegetable production. Mix humus with top soil and use In agriculture Mix excreta, soil, wood ash and leaves Allow to compost and form humus
Method 2.1 Making humus in shallow pits with The Fossa alterna is an alternating shallow pit system in which soil, ash, leaves and excreta (faeces and urine) are added regularly to the pit. The system uses two pits but only one pit is used at any one time, whilst the second composts the mix to make humus. The use of the pits alternates at yearly intervals. Because soil, leaves and ash are added regularly to each pit, the excreta can change into humus within 12 months - the filling time for a shallow pit (1.2 1.5 m deep) used by a family. the Fossa alterna
How the Fossa alterna works
How the Fossa alterna works
How the Fossa alterna works After one year of composting a mix of excreta, soil, leaves and ash, the pit contents can be excavated. The pit shown below was excavated in 30 minutes.
The Fossa alterna in Zimbabwe In Epworth (left) and Marlborough (right)
The Fossa alterna in Mozambique The Fossa alterna is very popular in Mozambique. It is seen as a more permanent solution than the conventional pit latrine, and its shallow pits are easy to dig by the household. The nutrient rich humus is also o favoured in areas where the soil is very poor. The regular addition of soil and ash also helps odour and fly control, in areas where vent pipes are too expensive to install.
The Fossa alterna in Mozambique The Mozambique ecosan programme in Niassa Province is run by a partnership of WaterAid (UK) and a local NGO, ESTAMOS. The construction of demonstration latrines, a thorough educational programme p using the PHAST technique, and the offer of a choice of technologies helps to promote the programme. Radio interviews with users are also used as a promotional tool. At least 500 Fossa alterna have been constructed in Niassa,, and the demand is considerable.
The Fossa alterna in Malawi The Malawi ecosan programme is funded by WaterAid in Salima,, and also in Embangweni and Ekwendeni (under the CCAP). Canadian Cida, through COMWASH, supports projects in Thyolo and Phalombe.. Most projects use the Arborloo to start and then move towards the Fossa alterna.. As in Mozambique the two Fossa alterna pits are often enclosed in a single permanently sited superstructure, often made of bricks. Grass structures are also be used.
Humus from the Fossa alterna On n the left a mix of faeces, urine and soil. On the right a mix of faeces, urine, soil and leaves.
Nutrient levels in humus taken from Fossa alterna pits compared to local top soils Soil Nitrogen Phosphorus Potassium Top soils (N = 9 ) Fossa alterna (N = 10) 38 ppm 44 ppm 0.94 ME/100 gms 275 ppm 292 ppm 4.51 ME/100 gms Increase X 7.2 X 6.6 X 4.8
Enhanced growth of vegetables with Fossa humus Lettuce (left photo) & Spinach (right photo) are shown growing on poor local topsoil (left bucket) and a 50/50 mix of local top soil (right bucket) and Fossa alterna humus.
Enhanced growth of vegetables with Fossa humus Rape (left photo) is shown growing on poor local topsoil (left bucket) ) and a 50/50 mix of local top soil and Fossa alterna humus (right bucket). Onions grown in the mix have nearly 3 X times the weight of onion n grown on poor topsoil alone
Enhancing vegetable growth with Plant, topsoil and growth period Spinach on Epworth. 30 days Covo on Epworth. 30 days Fossa humus Weight at cropping Poor top soil only Weight at cropping 50/50 mix of poor topsoil and FA soil 72 grams 546 grams (x7) 20 grams 161 grams (X8) Covo on Epworth. 30 days 81 grams 357 grams (X4) Lettuce on Epworth. 30 days Onion on Ruwa. 30 days Green pepper on Ruwa.. 30 days Tomato on Ruwa.. 30 days 122 grams 912 grams (X7). 30 days 141 grams 391 grams(x2.7) 19 grams 89 grams (X4.6) 73 grams 735 grams(x10)
The Fossa alterna garden A small backyard vegetable garden can be linked to the Fossa alterna toilet. Every year the humus from the toilet is mixed with the topsoil t of the garden and the additional nutrients can help to increase production. The addition of garden compost and leaf compost can also help enhance production. The careful addition of diluted urine, can also help production, particularly of green leafy green vegetables.
The Fossa alterna garden Seedlings of rape and spinach are planted and watered. After about 5 weeks a good harvest of vegetables can be reaped. Below on left, Rape and spinach seedlings being planted on 22nd November 2003. On the right the crop just before harvesting on 30th December 2003. The garden is linked to the Fossa alterna and the well composted pit humus and other composts from the garden are added to the topsoil l to retain soil fertility.
Method 2.2 Making humus from faeces derived from a single vault urine diverting toilet In this urine diverting system using a single above the ground vault, urine is diverted into a plastic container and the faeces drop into a bucket. A mix of dry soil and wood ash are added after every deposit of faeces.
Parts of the single vault urine diverting toilet
Parts of the single vault urine diverting toilet
Urine diverting pedestals and squat plates can be home made
Making humus from faeces derived from the urine diverting toilet The mix of faeces, dry soil and wood ash held in the bucket are regularly added to a secondary composting site like a 30 litre split cement t jar, or shallow pit. More soil is added. The process is repeated until the t jar or shallow pit is nearly full. The contents are kept moist. It is allowed a 4 months to compost. The resulting humus is rich in nutrients. The texture of the humus is improved further if leaves have been added. Soil UD toilet N ppm P ppm K ME/100g 232 297 3.06 Fossa 275 292 4.51 Topsoil 38 44 0.49
Vegetables and trees grow well on the humus formed from combining faeces, soil and ash. On the left tomatoes have grown spontaneously in jars filled with h the mix, and kept watered. On the right young trees of many types are offered a good start to life by being planted in such jars. Later they can be transplanted.
Method 2.3 Making humus from faeces derived from a double vault urine diverting toilet The urine diverting system can also be used on a double vault system. In this case two vaults are built above the ground and only one is used at any one time. Urine is diverted and the faeces drop into the vault followed by a mix of soil and wood ash. Once the used vault is full the urine diverting pedestal or squat plate is moved over the the empty vault which is then used. Each vault should take about a year to fill.
Method 2.3 The double vault urine diverting toilet
Method 3 Using urine as a plant nutrient Urine is a rich source of nitrogen and also contains several other useful plant nutrients in smaller quantities such as phosphorus and potassium. These nutrients are valuable for plant growth An adult excretes about 1.5 litres of urine a day Urine Constituents % Kg/Yr Water 96.98% - nitrogen 0.53% 3.08 Phosphorus 0.04% 0.23 Potassium 0.14% 0.81
Urine diluted with water and applied to plants can enhance growth significantly. Leafy green vegetables like spinach are particularly responsive.
Urine as a fertiliser for green vegetables These photos show the spinach production over a one month period using a 3:1 mix of water and urine (0.5 litres) applied twice a week to each 10 litre basins containing the vegetables, compared to the addition of water only. Crop yield increased from 741gms (22 plants) to 2522 gms (22 plants) as a result of the urine application an increase of 3.4 times. All plants were fed water at all other times to keep healthy
Urine as a fertiliser for green vegetables These photos show the rape production over a one month period using a 3:1 mix of water and urine (0.5 litres) applied twice a week to each 10 litre basins containing the vegetables, compared to the addition of water only. Crop yield increased from 160 gms (9 plants) to 822 gms (9 plants) as a result of the urine application an increase of 5 times. All plants were fed water at all other times to keep healthy
Urine diluted with 3 parts of water, applied weekly, greatly enhances the growth of plants like onion and covo in containers. It is a no cost natural fertiliser
Enhancing vegetable growth with urine Plants were grown in 10 litre containers and fed 0.5 litres of a 3:1 mix of water and urine, three times per week. Plant and growth period lettuce.. 30 days Lettuce. 33 days Spinach. 30 days Covo.. 8 Weeks Tomato. 4 months Weight at cropping no urine Weight at cropping With urine application. 230 grams 500 grams (x2) 120 grams 345 grams(x2.8) 52 grams 350 grams (X6) 135.5 grams 545 grams (X4) 1680 grams 6084 gms (X3.6)
Influence of urine on maize growth (applied as 3:1 water/urine mix (0.5 litres) three times per week to 10 litre containers).
Urine can also have a significant effect on the growth of maize. Here maize plants have been fed with different quantities of urine in 10 litre basins. The nearest basin has been irrigated with water only, others with increasing concentrations of urine and water
99.4% of the maize cob mass shown in this photo is derived from nutrients supplied by urine diluted in water (3:1) applied to plants growing in basins.
Enhancing maize growth with urine in the fields Undiluted urine was applied to small holes made close to maize plants p growing in the fields at the rate of 100mls per plant per week. Natural rainfall diluted and distributed the urine. This treatment led to an increase in mean cob weight of 28% and 39% in two treated areas compared to a not treated area. In a fourth area the plants were fed normal chemical fertiliser which led to a 61% increase in cob weight. Whilst less effective the urine treatment cost nothing. ng.
Ecological sanitation has taught us several important points about excreta: 1- Humus formed from human excreta is a valuable resource and can greatly enhance the growth of trees and food products. Urine is also a valuable source of nutrients. 2. Human excreta can be converted into useful humus by combining it with soil in equal proportions. The final product is improved if wood ash and organic matter like leaves are also added. 3.. Under the ground, excreta converts fastest in unlined, well drained shallow pits. A full year must be allowed for the conversion to take place
Can ecological sanitation solve some existing problems with conventional sanitation?. In Zimbabwe today there are at least half a million family VIP latrines each has a pit life of 10-12 years One thing is inevitable most will eventually filled up and the toilet will be abandoned. Is all the cost and effort, just for the benefit of a couple of generations? Or are there ways of rescuing the situation by applying some of the eco-san principles?
There are problems with the conversion of excreta in existing VIP latrines both in Zimbabwe and South Africa 1. The pits are filled with rags and garbage as well as excreta 2. Excreta by itself, without soil or ash/leaves converts into humus slowly 3. Pits filled with garbage and rags are difficult to excavate 4. The pits are lined with bricks or concrete rings, which means the excreta/soil interface area is small. 5. This reduces the rate of conversion of excreta into humus
However there are ways of moving on! 1. Once the superstructure and pit slab have been removed, the full pits can be topped up and rammed with soil and vegetable matter which helps to increase the rate of composting, at least in the upper layers. 2.. However the garbage will remain in place, making the pit difficult to extract. 3. But it helps if the removed material is humus rather than half decomposed excreta
After topping up with soil the original pit can be planted with a tree, such as a paw. Many trees will grow on the organic material in a pit. If the tree chosen has a soft wood, like paw paw, the entire tree can be dug out once the times has come to excavate. The roots of trees and other plants may actually help to decompose the converting excreta.
Try using a second pit and moving the slab and structure across! 1. A second pit must be dug and protected so that the removed slab and structure can be repositioned. 2. The use of a second pit allows for the contents of the original pit to compost further
Even with brick structures it is possible to recycle much of the toilet Here the roof has been removed from a brick VIP and the walls are being taken apart. It helps to do this carefully to avoid a loss of bricks. Any concrete work like roof and slab can be reused.
Recycling the lot! The building materials can be reused and even the pit contents can be mixed with additional materials (soil and vegetavle matter) to promote composting. In the end all that is not recycled is the brick pit lining.
The long cycle alternating pit With two permanently sited pits which are slightly deeper we have what might be described as a long cycle Fossa alterna.. The structure and slab can be moved from one site to the other at periods of a two or more years if the pits are dug deeper. There are many possible designs.
The recyclable brick superstructure This brick superstructure is built around a steel frame fitted with w sprags. The fired bricks are bonded with weak cement mortar (20:1). The asbestos roof and pipe are long lasting and can be removed easily. The pedestal is home made from a plastic seat over, bucket and cement work. A builder can take the unit entirely apart and rebuild in a few hours.
This new generation of twin pit latrine can be built by recycling parts of the single pit latrine. It is built & used in a slightly different way. The twin pits are shallower The parts of the unit are made more portable A combination of excreta, soil, ash and leaves are put down the pit. The pits are not used for garbage disposal. There must eventually be an acceptance that the pits are manually excavated.
Overall conclusions Eco toilets offer a wide range of options suitable to a wide range of potential users. Even with the lowest cost options, the toilets can provide far more m than a safe sanitary disposal system. The humus derived from shallow pit eco-toilets and urine diverting toilets is rich in nutrients and can greatly enhance the production of vegetables when mixed even with the poorest of top soils. The urine also has great value as a liquid plant food when diluted with water. It is particularly valuable for green vegetables and maize. When harnessed together both eco-humus and urine have enormous potential for enhancing food production in both rural and urban areas. Ecological sanitation offers hope and forms vital links between health, sanitation and agriculture. By adopting some of the eco-san principles, some problems with existing excreta disposal methods, such as the pit latrine may be b overcome.