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Leticia and its need for a wastewater treatment plant

The city is far from promoting a civic culture and environmental education promoting love and respect for the city and its surroundings. Walking the streets one sees garbage on the sidewalks, parks, and wetlands as if they wanted to show the lost habit of “littering the city”. Added to the precarious public utilities there is a lack of culture to collect, dispose, and place waste where they should be.

Many regions of the country can be an example to teach garbage disposal–especially solid waste– that reach the streets and parks of Leticia, and the edges of the cities’ wetlands, inclusively to the Amazon River, and logically without any kind of management or selection process, and end up in the so-called open-pit landfill outside the city.

There, more than 60% of the garbage is comprised of organic waste which is not being utilized despite all the current technologies available to reuse organic matter and much of which may be reused as compost, fertilizer, and biofuel among others and also produce resources for small businesses, associations or organizations that support a better environment for the region.

Read more: Essential oils will boost green businesses of the Amazon.

Liquid waste and a treatment plant

Hopelessly liquid waste turns into sewage waters that reach water sources such as wetlands, water streams, and the Amazon River. A load of these effluents increases when households throw their organic waste in the house drain, which on the contrary, could be collected and have a selective garbage collection in Leticia.

The city is set back several decades in its Public Utilities Master Plan1 and therefore the network that receives the sewage is poor and deficient and part comes to the surface contaminating “city wetlands” where most of the cities’ waste and garbage ends up along with rodents and insects of all kinds.

A research project headed by Universidad Nacional de Colombia (UNal) – Palmira Environmental Engineer Carlos Andrés Ferreira, with the collaboration of UNal-Amazonia and the Amacayacu National Park made a diagnostic of the septic tanks for the treatment of domestic wastewater installed by the indigenous communities of San Martín and Mocagua, territories that cross the aforementioned park. They discovered that the effluents with high contaminating load can infiltrate and impact nearby aquifers and even reach rivers, water streams, and wetlands. Septic tanks are an alternative for the treatment of domestic wastewaters in urban and rural settings without access to public utility networks as is the case of the touristic area of the Amazon.

Read more: Indigenous health, traditional medicine, and Covid-19 (in Spanish).

In Colombia, every municipality with more than 10,000 inhabitants should have a wastewater treatment plant (WWTP). Although Leticia is in the process, there are currently two positions, one in favor and one against a comprehensive WWTP in the city. Social movements such as the Amazon Environmental Defense Committee support the need to adopt a better-planned solution.

The WWTP is not the solution to all the environmental issues of the city, as when one problem is solved at the end of a system or chain, the causes are not addressed and therefore the best environmental results are not warranted. The WWTP is a system that improves the physical, chemical, and biological conditions of residual waters of a city before releasing them into a natural water source. This occurs using of a series of physical, chemical, and biological processes within the treatment plant and that has the purpose of eliminating the pollutants present in the water.

In general, the receiving end is a water stream, a brook, or a river that is distinguished by the size of the lotic ecosystem, as water current systems are known, as opposed to lentic ecosystems, which are still waters such as lagoons and lakes.

Here we will define the flow of the receiving source and the flow of the effluent. The flow is a measure of the amount of water that passes through a determined point and measured in liters per second (l/s) or cubic meters per second (m3/s).

Leticia has an average value of 100 l/s of wastewater, most of which reach the Amazon River.

It would be good to know if in the definition of the Public Utilities Master Plan and the comprehensive WWTP considered and valued one of the most important ecosystem services provided by the Amazon River, which is to breakdown and dilute organic matter provided in wastewater. As there is any large industry that releases other types of compounds (such as heavy metals), organic matter is the main issue to be addressed by a WWTP or the river as is being proposed.

Read more:  Colombia, disadvantaged in marketing cat’s claw in a sustainable manner.

What happens in Leticia?

In Leticia, the Amazon River has a changing flow of between 16,000 m3/s during the second semester of the year when the waters are low and a maximum of 60,000 m3/s in the first months of the year; this data is taken from the Nazareth straight, a few miles upstream from Leticia.

In front of the city the river opens into two water channels, the larger channel leans right toward the Island of Santa Rosa (Peru), and the other, is located between Santa Rosa and the Isla de La Fantasía (Colombia) close to Leticia. The flow in this channel can be around 20% of that of Nazareth, taking into account that this data varies depending on several entities and the current sedimentation evolution.

This low flow is about 3,200 m3/s. Therefore the effect of the non-treated wastewater from Leticia would be 0.003%. Knowing that the Amazon River is an immense metabolizer of organic matter, it alone could solve the environmental issue at this point. Some technologies allow diluting these small wastewater flows without producing foul odors and possible optical contamination issues. Colombia has solved this in part in the Bay of Cartagena with an offshore piping system.

However, the environmental issues of Leticia will continue with or without a WWTP, as the plans of the authorities do not show any evidence of approaching this issue comprehensively. In Colombia, there are regulations, policies, intentions, and actions in favor of managing or diminishing solid waste, but not much is done at the primary source (people, businesses, households). So without a substantial improvement in civic culture and formal and informal environmental education at all levels of society, every improvement effort will be lost.


1 The project began in February of this year, just a month before declaring the pandemic in the world.



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