Sinking city, rising tech: can a megacity recycle itself?

 

In 1325, Mexico’s largest city, Tenochtitlan, was built atop the ancient Aztec lake of Texcoco. Its population relied on chinampas (human-made floating islands) for farming fresh food, preventing erosion, filtering the lakewater, and to act as the habitats for wildlife such as the axolotl. Collaboration with the natural world made Tenochtitlan highly self-sufficient and ecologically stable.

Unfortunately, the same cannot be said 700 years on. In what has now become Mexico City, overconsumption has plunged the city into an environmental crisis.

Two factors drive this crisis: water and waste. Overconsumption of water and insufficient management of waste are pushing the city towards a state of emergency. To solve the crisis, the city needs to not just reuse water and waste, but to renew its entire urban model.

Since 1950, Mexico City’s population has expanded from 3 million to nearly 24 million. With it, the production of rubbish and demand for water have exploded. Over-extraction from aquifers (layers of rock or sediment that hold groundwater) has led to water shortages and flooding, while the city’s waste output — which amounts to roughly 540 tons every hour, and 40,000 litres of sewage every second ¹ — is inundating the city’s recycling infrastructure.

Think of it like a mattress: as more water is pumped from beneath, the once-supportive cushion sags under the weight of the ever-expanding urban sprawl. With impermeable concrete surfaces blocking rain from replenishing the aquifers, water stores cannot recover and flood risk increases. ².

First, let’s tackle water.

It seems almost inconceivable that a city can simultaneously experience frequent floods and water insecurity, yet this is Mexico City’s reality. Of the city’s residents, 1 in 5 can access only a few hours of tap water per week (BBC) — water, let’s not forget, that cannot be drunk due to high levels of contamination. This paradox is what the innovative rainwater harvesting program, ‘Agua a tu Casa’, seeks to address as it turns vulnerability into a solution.

Launched in 2016, the programme has installed rainwater harvesting systems and water purification technologies within homes and public buildings in marginalised areas such as Iztapalapa and Tlalpan (source) — saving 75 million litres of water (C40) in just its first year. Nearly 500 systems have been installed since, benefitting more than 56,000 people (Go Explorer).

Beyond its environmental role, the programme supports gender equity by training women affected by domestic violence to install and maintain the systems, offering them both practical skills and a path to empowerment.

Meanwhile, because aquifers supply 40% of the city’s water ³, monitoring their quality is critical. One promising technological solution is JAKEBOT, created in UNAM — Mexico’s largest public university. JAKEBOT tracks water quality in real time, predicts future water conditions, and triggers an alert when pollution levels rise. When deployed in a river in Veracruz, it informed the local population on the inextricable link between the environment and public health and laid the groundwork for smarter, safer water use. Innovative tools and research help prevent contamination and encourage the safe reuse of water: key steps in achieving a circular water economy ⁴.

But what about the city’s waste?

Some argue that the key lies in the transformation of waste into energy, and Mexico is home to the first facility in Latin America to do just this. Since 2022, the waste-to-energy plants, built and operated by Veolia ⁵, have turned 40,000 tons of waste ⁶ into renewable energy each year.

Once non-recyclable waste — such as plastic — arrives at the plant, it’s burned at a very high temperature. I know what you’re thinking: doesn’t burning plastic release even more toxic fumes into the ozone? These fumes are released into a controlled environment that intercepts and traps most of the harmful gases before they escape into the atmosphere. The heat produced is then converted into electricity via steam-powered turbines.

Francisco Torres, Managing Director of the sustainable solutions company Veolus, says this adds a fourth, albeit not quite as melodious, ‘R’ to the familiar mantra: reduce, reuse, recycle — and ‘recover energetically’. By retrieving materials that would otherwise be discarded in landfill, these environmental centres reposition waste not as a burden, but a resource. They address both pollution and the high energy demands of Mexico’s population. Sounds idyllic, doesn’t it?

But they’re not perfect: they can’t capture 100% of the pollutants and they risk discouraging citizens from reducing or recycling in the first place.

Mexico City resident, María Fernanda Serrato, isn’t given the option to recycle in her apartment block. She puts it plainly: “It takes six blocks to reach a trash can. If there aren’t even bins around the city, what hope is there for recycling?”.

Before investing too heavily in a fourth ‘R’, the city must first make the original three truly accessible.

Anyone who has spent even a few days in Mexico City will be familiar with the chant that begins with ‘se coooompran’. The rest of the chant follows: “colchones, tambores, refrigeradores, estufas, lavadoras, microondas, o algo de fierro viejo que vendan”. Which translates as: “we buy mattresses, washing machines, fridges, stoves, microwaves, or any scrap iron that you may sell”. This recording is blasted through speakers attached to pick-up trucks that traverse the city in search of used devices that are then resold or recycled.

However, this informal system of recycling is under threat. A recent reform criminalises collectors without a government license, imposing fines and even jail time. While the intention is to formalise waste collection, it seems the government’s focus is misplaced. Instead of penalising recyclers, authorities should be installing more public bins and enforcing building-wide recycling options.

Fortunately, grassroots initiatives are filling in the gaps. Reciclatrón, a monthly e-waste collection event launched by the city council and UNAM, encourages proper disposal of electronics to prevent highly toxic liquids from contaminating soil and aquifers ⁷. Herberto Ferreira, from the Institute for Sustainability at UNAM, warned that “this type of pollution is irreversible” ⁸. Before the city is permanently damaged, the government must invest in small-scale measures that raise public awareness and put citizens at the heart of climate action.

Mexico is emerging as a key player in the green revolution, but no amount of smart tech can substitute for basic infrastructure, accessible services, and informed civic action. As climate pressures mount, the solution won’t come from solely burning waste or filtering rain — it will come from a city learning, as it once did under Aztec rule, to work with, rather than against, the environment that sustains it.

 

Edited by Claire Whitehead 

Copy-edited by Cameron McKeddie

1. https://www.bbc.com/future/article/20180510-how-a-city-that-floods-is-running-out-of-water
2. Read my previous article about the city’s spectacular geography here https://glasgowuniversitymagazine.co.uk/articles/features/the-laboratory-of-the-extinction-of-the-species/
3. https://www.bbc.com/future/article/20180510-how-a-city-that-floods-is-running-out-of-water
4. Take a look at the full paper here https://virtual.cuautitlan.unam.mx/intar/wp-content/uploads/sites/14/2023/02/Int-Art-54-59.pdf
5. read the Press Release here https://www.veolia.com/sites/g/files/dvc4206/files/document/2017/05/CP_Veolia_UVEMexico_220517_ENG_2.pdf
6. https://comercial.reforma.com/libre/comercial/campanas/Industrialparks_23/8.Waste-to-energy_in_Mexico.html
7. read more about it on the government website here https://www.sedema.cdmx.gob.mx/programas/programa/reciclatron
8. https://mexicobusiness.news/tech/news/mexico-ranks-10th-globally-e-waste-generation