This artificial wetland is reusing wastewater to restore lost ecosystems
With drying The wetlands of Las Alitas, a region south of Mexicali where pale deserts dominate the landscape, feel like a mirage. But it’s real and an oasis of endemic and migratory birds across the Colorado River Delta. Here is a second life using the waters of Mexicali City, just south of the US-Mexico border. Half of them head to the nearby Hardy River to restore an ecosystem that was thought to be irreversible.
Historically, the waterways here are filled with sewage –Especially the new riverdrove north off the Colorado River, then travels from Mexico to the US, ending in the Salton Sea in California. For years, this waterway received untreated sewage from Mexicali, Render it One of the worst rivers of its size in the United States. In the 1990s, American and Mexican authorities were unable to ignore how bad the problem had become, and began working with infrastructure to reduce pollution. Therefore, in 2007, the Las Arenitas treatment plant, south of Mexicali, began operations.
Sitting at the border, Mexicali produces more than 80 million cubic meters of sewage per year. Of that total, 90% will be collected, and 46% will go to Las Aritas.
In a sewage plant, solids and sediments are first removed from the wastewater. Next, the lagoon where the surface was generated is used. There, air is injected into the water to stimulate the growth of aerobic bacteria that break down organic matter in the presence of oxygen. The water then passes through facultative lagoons where aerobic and anaerobic bacteria complement each other, the latter complementing organic matter that the former could not. Finally, the water reaches the mature lagoon, and the remaining solids settle.
When I booted up, this new system worked. “Initially, the factory didn’t ideally perform,” says Edith Santiago, deputy director of Mexicali’s Colorado River Delta Program, a Sonora conservation nonprofit. To address this, some organizations have proposed to water management agencies to use the surrounding land that housed the lake decades ago to create constructed wetlands that would give the water additional cleanliness.
Such a plan will not only support the city’s sewage issues, but will also help to partially restore the local landscape to its former state. Before the Colorado River was overexploited, its delta crossed California and Sonora until it met the waters of the Gulf of California, bringing more than 400,000 hectares of wetlands. The river course has become ghosts, but about 15% of these wetlands survive and carry incredibly valuable biodiversity of plants and animals. The Las Arenitas Artificial Wetlands, which seek to mimic that strength, are a pause against the devastation of local landscapes.