Wastewater treatment in Mexico
Every year millions of cubic meters of wastewater, municipal, industrial and agricultural discharges are discharged into water bodies that are inadequately treated or without any treatment. Water pollution has a severe impact on ecosystems and health. It is necessary to reduce volumes and improve treatment processes, not only to ensure social welfare and environmental protection, but also for economic and national security reasons.
What happens to the used water once it reaches the drain?
In wastewater treatment, Mexico faces a great challenge to combat pollution due to the lack of effective and efficient infrastructure for the treatment and reuse of wastewater.
There are many treatment plants that do not work well, others that do not work, simply because the costs of operation and construction of collectors were never considered; likewise, the municipalities do not have funds to cover them. Other plants have systems that contaminate surrounding areas with potentially dangerous aerosols or solid or pasty waste.
In addition, in the country, most of the wastewater treatment plants are based on processes that in some countries are considered obsolete due to their enormous energy consumption and due to the amount of solid waste and hazardous aerosols that they produce and that, in turn, they must also be treated.
In Mexico, wastewater discharges are classified as municipal (urban and rural public supply) and non-municipal (other uses such as self-supplied industry). According to official figures, 52.7% of the municipal water generated is treated, and 32% of the non-municipal water.
Although there is progress, it is still insufficient and there is an undetermined volume of contaminated water that is not collected, that is lost in the drainage networks or that is illegally discharged directly into the environment. It is estimated that in 2015 the economic cost of pollution caused by untreated wastewater was 57,403 million pesos, equivalent to 0.3% of gross domestic product.
The reduction of water pollution requires a strong investment in infrastructure for the treatment of wastewater and would represent a saving in terms of medical attention that must be given to the treatment of diarrheal diseases caused by contaminated water and agricultural products. In 2015, 3 754 people died in Mexico due to intestinal infectious diseases.
Investing in the infrastructure necessary to increase wastewater treatment capacity represents a long-term gain by reducing the costs of pollution, overexploitation and transportation of water. These costs will increase progressively with population growth – particularly in urban areas – as pressure on water resources intensifies.
There are two types of wastewater treatment systems based on biological processes: aerobic and anaerobic. The former provide a high oxygen content environment for bacteria to degrade organic matter in the waste, are highly energy demanding, generate a lot of sludge and few resulting gases. The latter use bacteria that, by decomposing organic matter in the absence of oxygen, produce less sludge and release more gases (methane and carbon dioxide, ammonia and sulfuric acid) that, within the framework of comprehensive use, can be used as fuel.
By treating wastewater, considerable savings are generated by releasing first-use water for activities such as cleaning and irrigation, reducing water pressure and overexploitation of aquifers, and preventing contamination of water bodies and diarrheal diseases. , which has a positive effect on the environment and the well-being of the communities.