Latrine compost

Contents of a latrine drum
The contents of a latrine drum vary greatly depending on the type
of toilet it comes from – with or without urine separation.
With urine in the barrel, it is a very wet and nutritious mass. Without urine, it is quite dry and poor in nitrogen in particular. Toilet paper is also dry and nutrient-poor.

The data on volume approximates the amount of urine between 1 and 2 liters per person.

Latrine waste can contain infectious material, such as bacteria
and viruses. It must therefore be handled in such a way that no
infection is spread. Note that what is said here about latrine composting is also valid for those who have a pre-digestion toilet, often called a mulltoa or multrum.

Preparation
Before you start composting your latrine, find out what your local authority says about latrine composting. If you do not already have a
urine-diverting toilet or urine-diverting insert in your outhouse,
you should also consider whether you should start urine-diverting. It usually
makes composting easier.

Common rules
There are usually strict municipal rules on how latrine waste should be handled during composting, as it may contain infectious material.
Rules may vary from one municipality to another. Therefore, find out what applies where your property is located. The rules can often be found on the municipality’s website, or by calling
to the municipality’s environmental and health protection office.

Municipalities usually want the container to have a lid and a tight
bottom. The lid is to prevent rainwater and meltwater from
entering, and the bottom to prevent any infectious bacteria
from reaching the groundwater and ending up in a drinking water well.

The material must remain in the container for a minimum period of time after the last filling, usually 6 months or 1 year in frost-free conditions, before
it can be removed. During this period, it is expected that the
infectious bacteria will have died. To ensure this,
the municipality usually requires a latrine composting facility
to consist of two separate parts, which in practice means
two different containers.

Compost bins must also have a certain volume, generally 350 liters
in each bin if only latrine is to be composted, and
500 liters if it is to be co-composted with food waste. Note that the volumes apply to holiday homes. If it is a year-round residence,
double the volume is usually required.

If food waste is also to be composted, the compost bin
must also be insulated. However, if it is mainly used in summer
, municipalities often make exceptions to this requirement.

With or without urine sorting?
A person produces more urine in a day than feces and toilet paper. Sorting urine or not sorting urine therefore creates completely different conditions for the composter. It is possible to compost latrine even if there is a lot of urine in the material, but it is much easier without the urine.

Therefore, get a urine-sorting insert in the outhouse or
a urine-sorting toilet indoors. Urine sorting does not
only make handling easier. It also provides a more pleasant toilet solution
with reduced risk of odor and an easier barrel to carry.

If the urine is managed so that the nutrient content is used as fertilizer, the urine-diverting toilets also have very good
environmental performance, probably better than any other toilet system.

What do you do with the urine?
If you sort urine, you have to take care
not only of the contents of the latrine barrel. You also have a canister or tank
of urine to deal with, which will be spread on growing land.

With urine sorting
In a urine-sorting toilet, the contents of the latrine barrel are drier and
nutrient-poorer, especially in terms of nitrogen, than if urine is present.
However, it still contains a lot of both phosphorus and
potassium.

Latrine bags
If you are sorting urine and using an insert bag in the latrine barrel
, you can use the most easily degradable bags,
for example corn starch bags. They normally do not have time to start
breaking down in the bin, but take the shortest time to break down in the latrine compost.

Do not tie the bag of contents together and place it in a
corner of the compost, as this will take a long time to decompose. Instead, pour
the contents out of the bin and throw the bag into the compost.
Peat moss. When you sort urine, you do not need to put as much
absorbent material in the bottom as if you do not sort urine. A thin layer of peat moss or heat pellets, 10-15
cm, is
sufficient. More is needed if you use other bedding materials, or if you
expect to continue with the same compost for more than a year.

Location of the compost bin
As mentioned earlier, a latrine composting facility
consists of two separate compost bins, which in turn means that it requires both working space and a relatively large area to accommodate them.
However, municipal regulations rarely
include any rules on where the container should be placed on the plot. However, for
safety, you can avoid placing it near a drinking water source or where it will disturb the neighbors in any way. If you have a choice between a shady and a sunny spot, choose the shady one. This way, the compost will be more likely to live its own life and not be affected as much by the sun.

Here’s how
At every stage of latrine management, from the urine-sorting insert
in the outhouse or urine-sorting toilet to the compost, there are
things you can do to make life easier for yourself.
Using insert bags in the latrine drum and priming the bottom of the latrine compost with
peat moss are such measures.
Compostable insert bags. To simplify and make the handling
of the emptied barrel more pleasant, it can be fitted with a compostable insert bag. It works both for urine sorting and
without. The bags are of a more or less degradable type depending
on the material they are made of.

Current material
Since the whole point of a latrine compost bin
is to have a tight bottom, it is inevitable that liquid
will accumulate there: urine from the latrine barrel and water, which is a product
of the process. To prevent the liquid from reaching the material to be
composted, it is advisable to fill the bottom with peat moss.
The simplest type, unlimed and unfertilized or natural, will do.
pellets, which also have a high absorption capacity, can also be used as a base material, but peat moss is both cheaper and easier to reuse in the garden.

The amount of peat moss to put in the bottom depends on whether or not the latrine drum contains urine, and how much to compost, which in turn depends on how long you keep filling the container. You can choose to keep filling it until it is full. You can also switch between containers every year if you prefer, for example to access the compost as quickly as possible.
The longer you keep filling the same compost bin
, the more liquid will build up, and the more peat moss or pellets you should add to the bottom.
The bottom layer should not be mixed up with the compost material. It
should remain to take care of the liquid.

Top up with a 20-30 cm thick layer of peat moss or heat pellets. More is needed if you are using other materials or if you expect to keep adding the same compost for more than a year.

Filling.
Keep a grab handy when emptying the latrine barrel.
Make a small pit in the compost material, empty the barrel and cover
it. This will suffice for mixing during the active period.
Bedding material. Many people have probably already put bedding material in the
latrine barrel. In most cases, this is not enough and you will need to add
additional material to the compost bin. Mix in enough
bedding so that it does not get too wet in the compost, but on the other
hand not so much that it becomes too dry.

Without urine separation
With a toilet that is not urine separating, all the urine ends up in the latrine tank, whose contents are therefore very wet. It is also very nutritious. It requires more composting than if the urine is sorted out.

Latrine bags & insert bags
If you do not sort your urine and use an insert bag in the latrine bin, you should use the most non-degradable bags.
If you use a more easily degradable bag, it can start to break down
in the bin. Remember to pour the contents out of the bag and then
throw it in the compost. If you leave the material in the bag
it will take longer to decompose.

Emptying.
A latrine compost does not normally operate at the same
high temperature as a household compost. The temperature is often
not much higher than the ambient air and in a holiday home, where there
is no refilling in winter, the material freezes. However, it
thaws in the spring and the process continues again.

A properly managed latrine compost normally takes about 1 year to produce finished compost and can then be emptied. This also means that the municipal regulations on emptying no earlier than 6 months after the last filling have been met.
Expect there to be a risk of odor when you dig out the wet bottom material. Work the material into the garden compost
or cover it with garden compost or soil for a while and the smell will disappear.

Handling of urine
If you have urine sorting, you don’t just have the latrine barrel to deal with.
You also have a canister or a tank to take care of. Urine contains a lot of nutrients. This makes it an excellent fertilizer, but it can also make it an environmental hazard if used inappropriately.

Two options
Diverted into the ground to a pit or infiltration facility, or spread above ground as fertilizer. Not all nutrients are retained in the pit or infiltration system. Some of it moves on and fertilizes the nearest water body.

Urine can be used as a fertilizer on the plot. The nutrients are then taken up by the plants and do not migrate further.
This means, on the other hand, that spreading should only take place during the
growing season and that there must be capacity to store
the urine during the rest of the year. This is of course especially true when a
year-round residence has a urine-diverting toilet.

Dilution is not a must
Traditionally, it is often claimed that urine should be diluted with water in the ratio of 10 parts water to 1 part urine before it is used as fertilizer. However, this is not necessary.
It is possible to water with undiluted urine. If the same area
of the plot is watered with concentrated urine once or a few times
per season, there is no risk of the irrigated vegetation being
damaged. The fact that the place on the plot where the men
go to pee usually turns brown is because they go to the same place all the time. Diluting
the urine with water is more labor intensive than not doing
it. It is messy and it increases water consumption.

For those who want to dilute urine and make it less labor intensive
an ejector tank may be the solution. Concentrated urine is a
tougher environment for potential pathogens.
According to the Swedish Institute for Communicable Diseases, the less water in the urine the better.

Tricks when spreading. To reduce the risk of odor when spreading
, the treated surface can be re-watered with a little water. In the garden, the urine can be filled into a furrow next to the crop to be fertilized, after which the soil is put back into the furrow. Similarly, in the flower bed, the urine can be filled into a pit which is then filled with soil. It should not be applied to very young plants or directly to the plant to be fertilized, as this can cause burns to the leaves.
It should also be done no later than one month before harvest for hygienic reasons.
A convenient way to dispose of urine is to spread it on a
leaf compost. It needs a lot of liquid and nutrients, and handling is easy and odorless. Of course, the leaf compost must not be too small in relation to the amount of urine. Expect it to have at least ten times the volume of urine.

Possible amount of urine to spread per surface
A simple rule of thumb is that the available surface should be at least 1 m2 per person-day (i.e. the number of people times the number of days). For a family of four spending 30 days a year in the countryside, 120 m2 of vegetated land is sufficient.
If it is for permanent residence and the same family is assumed to meet half of its needs at home, just over 1 500 m2 is sufficient.

Storage in a tank
In the case of a year-round residence with a urine-diverting toilet, the urine should be collected and stored in a larger tank during
the winter months. This is to allow spreading during the vegetation period.
To reduce the risk of nitrogen losses to the air and odors from the tank, the urine supply pipe should be led into the bottom so that the filling takes place from below. The tank should not be hermetically
sealed, but does not need to be ventilated more than through
the gaps in the lid or similar.