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What dosage should I use to sanitise faecal sludge using lime?


Hydrated Lime Treatment is a cost-effective chemical treatment method for faecal sludge from pits and trenches. It uses hydrated or slaked lime (calcium hydroxide: Ca(OH)2) as an additive to create a highly alkaline environment and thereby stabilise sludge from human waste. It thereby significantly reduces the risk of latrine sludge causing negative impacts on human health and the environment.

The pros’ and cons’ of lime treatment


Short treatment time (6 Log removal of E-coli in <1day)
Simple process which uses readily available material
For liquid sludge – a sanitised and stabilised effluent is created suitable for soil infiltration.


High chemical input
Highly-alkaline sludge and effluent created
requires subsequent neutralisation
Lime quality can impact dosage rates Potential health risks if not handled properly

Design Considerations The treatment process can either take place above ground in a separate tank or below ground by digging a pit and lining with a tarpaulin in order to avoid leakage of highly alkaline effluents into the ground. In areas with high groundwater level or in flood prone areas it is recommended to always use above ground tanks rather than digging a pit. Separate tanks may be needed for the preparation of the lime slurry and for the post-neutralisation of the treated effluent respectively.

image description Source: Speedy Sanititazion And Stabilization. Appendix 2. Lime Dosage Determination Procedure –WASTE.
Note: If you use agricultural lime (calcium carbonate) and not hydrated lime (calcium hydroxide), the process will not work.

How to use it?

  • Hydrated lime treatment needs a reactor vessel which can either be an above ground tank (between 1-30m3) or a pit below ground with tarpaulin lining.
  • An additional smaller container is needed for the preparation of the lime slurry (e.g. 200l plastic drum). See here for video on how to make the lime slurry
  • For an even distribution of hydrated lime in the tank it is mixed into the sludge either manually with a shovel or wooden stick or with a mixing pump.
  • The type of pump required depends on the consistency of the sludge. A
    separate pump is needed for removing the treated effluent from the tank
    and a shovel or vacuum pump for the
    solid removal.
  • In addition a water testing kit (particularly for pH, E.coli, TSS and turbidity) is needed as well as personal protective equipment (PPE) like mask, gloves, boots, apron or suit and the respective chemicals (hydrated lime,
    magnesium sulphate if needed).

Further reading

Research on lime application – Emergency Sanitation Project https://emergencysanitationproject.wi...

Compendium of different sanitation technologies appropriate for emergency situations. Compendium of Sanitation Technologies in Emergencies (pending publication) German WASH Network, EAWAG, Global WASH Cluster.

Lime treatment as promising sludge sanitising method in emergencies Anderson, C. et al. (2015): Lactic Acid Fermentation, Urea and Lime Addition: Promising Faecal Sludge Sanitizing Methods for Emergency Sanitation, UCBI, URL: General overview on lime treatment and case study from the Philippines Strande, L. et al (2014): Faecal Sludge ... (more)

1 Answer


Here is a most interesting message on wastewater management. How to clean mud from material Trevisan. Therefore, the question what is the word restore? No, it's inexplicable for several reasons. Clean up is a general term. It must be complemented by action and target. The action to clean up: cleaning up an environment to know pollution of the environment. Is the fecal pollution? No. It is an organic material like all other organic matter on our planet. The better term for this kind of action is 'kill'. How to kill this organic matter always activation. Well make the difference between killing, make inert and destroy. the problem that then arises is the following: what stage of activation is this organic matter? We know that the author of the post defines it as mud. The mud is always organic material? Yes. What in means that there must be a difference between the organic starting material and mud. Actually in scientific communication of lyseconcept it is explained that the mud is the final phase of the process of biodegradation of organic matter.

As such, there are steps in the process of destruction of organic matter. If a step is stopped the natural biodegradation process stops and the organic matter changes state: living organic matter it becomes matter organic mud. A living organic matter is destroyed very quickly and very easily by its natural process. a material organic mud destroyed in time month/year.

Domestic sewage consist of several types of organic matter. plant organic matter, organic matter body. This is what one finds in the food bowl. We like them both the same process of biodegradation? No. Mix them it induces a change in the process of biodegradation? Yes. That's where this summarizes the whole rather than management of feces but the treatment of excrement.

Wastewater contain different chemical and biochemical pollution. In the presence of oxygen these chemical and biochemical components change. There is already a need for caution at this stage.

These various biochemical and chemical pollution with inter is between them, will still react to the touch of another chemical action such as the addition of lime. We realize at this point that wastewater management services only offer alternative solutions without great results at the level of the cleaning of wastewater. These services play the sorcerer's apprentice at the expense of the environment, because this off mud will be stored under tarps in anticipation of a possible future treatment. These storage coverings are in the open air, the onslaught of wind and heavy rain that will lead by overflow in the environment, much of the pollution that is supposed to not go.

The author of the post change of term on two lines only. It's more fecal matter but the mud mud of human waste. So what is this human waste?

Fecal matter is part of the excrement that also contain urine. We desperately this new urine treatment in all the reports of management stations ... (more)