- Latrines and Wastewater Treatment
Liquid waste such as urine or vomit should be disinfected by pouring 0.5% chlorine solution and safely flushed into the sewer system if there is an adequate sewage system in place. Where there is no adequate sewage system, urine and vomit should be decontaminated 0.5% chlorine solution or bleach prior to being flushed into a soak away pit.
Temporary pit latrines are acceptable and preferred if space and geology allow for site containment. Temporary pit latrines can fill up quickly so it is important to ensure you have enough space and resources to construct and decommission temporary latrines (dose the excreta with lime to increase pH to around 12, cover with soil and compact). It is important to mark decommissioned sites with durable signs. Pour flush latrines connected to stabilization ponds should be considered if construction of temporary pit latrines are not an option and if space and geology allow. It is recommended to construct separate latrines for workers, confirmed cases and suspected cases based on the ratio of one latrine drop hole for each category of persons.
In order to minimise the volume of liquid undergoing treatment, separate grey water from black water and dose the grey water with additional 0.5% chlorine solution before discharge into a soak away pit. Should space and geology allow, construct a simple wastewater treatment unit/stabilization pond (with at least 1 hour retention time) with large volume sludge tanks with about two month capacity to maximise value. If possible, it is recommended to de-commission full sludge tanks on site and construct new ones to avoid high cost incineration of the sludge. If on site de-commissioning is not possible, ensure sludge has a high pH to accelerate the destruction of the virus before considering off site transportation/digestion/treatment. Common methods and agents for disinfection include sodium hypochlorite (NaOCl), chlorine dioxide (ClO2), ozone (O3) and ultraviolet (UV) light .
When designing wastewater management units in Ebola Care Centres/Units, it is important to consider alternative off-site disposal and treatment, distance to Centre/Unit, type of geology and topography, distance to water source, viral load, availability and suitability of site and numbers of patient, staff and waste management technicians required.
A key issue is the design of latrines which have little odor, no fly breeding, easy construction and affordability. This search began in Thailand back in 1959 and was influenced by a 1954 WHO publication by E. G. Wagner and J.N. Lanoix. India had experimented with a hand-made concrete bowl with a water trap to serve as a squat-plate pit latrine. This innovation became highly popular, attracting commercial groups to produce them in mass from porcelain and plastic. Virtually every rural Thai home has such a latrine, which is also popular in Malaysia, Indonesia, E. Timor. and elsewhere. A detailed write-up can be found in the publication: Choosing a Career in Development by Dr. Barry Karlin via Amazon.com
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