By: Diana Velázquez

97.5% of the water on Earth is salt water (oceans and seas), the remaining 2.5% is fresh water, less than half of the fresh water is in the form of streams and rivers and is deposited in lakes, lagoons or surface bodies of water and only 0.007% of the water on Earth is potable, this amount decreases year after year due to the pollution that continues its growth worldwide 1.

Among the most important pollutants of water (by human activities) are pathogenic microorganisms, nutrients, substances that consume the oxygen from the water, heavy metals and organic matter, as well as suspended sediments and pesticides. The industries that use organic raw materials are the ones that contribute to the increase of contaminants in a more significant manner, being the food sector the one that contaminates the most 2.

In Mexico, pollution and climate change have decreased the availability of water per capita from 11,500 cubic meters in 1955 to only 4,663 cubic meters in 2011. According to figures of the National Water Commission (Conagua) in 2011 70% of the national rivers showed some degree of contamination 3,4.

One of the most commonly used measures to control wastewater contamination is to subject it to various treatments and processes (physical, chemical and biological) in order to produce a reusable effluent in the environment and a solid waste or sludge (biosolid) suitable for disposal or reuse, however, every year millions of cubic meters of wastewater (municipal, industrial and agricultural) that is treated inadequately or that has no treatment is discharged into the bodies of water.

Wastewater treatment begins with the physical separation of large solids using grids, meshes or by crushing, followed by the separation of small solids through a sand filter. Subsequently suspended solids are separated by a primary sedimentation while, in order to remove dissolved metals, (lead and phosphorus mainly) precipitation reactions are used. Following this process, a transformation of the remaining pollutants is required through a biological process in which microorganisms are used. These microorganisms must have the capacity to degrade the dissolved organic matter and carry out a progressive conversion of this organic matter into a solid biological mass. Once the biological mass is separated or removed (secondary sedimentation), the treated water undergoes additional processes (tertiary treatment) such as disinfection, filtration, etc. The final effluent can be discharged or reintroduced back into a natural body of water (stream, river or bay) or to other environments (surface land, subsoil, etc.). On the other hand, segregated biological solids undergo additional treatment and neutralization before their discharge or reuse.

Although microorganisms that are already present in these waters are generally used for the biological process, it is possible to add exogenous microorganisms with specific metabolic capacities that can help to decompose organic matter more quickly (producing less sludge) and to release more gases (methane, carbon dioxide, ammonium and sulfuric acid) that, within the framework of an integral use, can be used as fuel situation that increases the efficiency of the treatment systems.

Water pollution has a severe impact on ecosystems and health, which is why it is necessary to improve treatment processes, by doing so this will generate considerable savings by releasing first-use water for activities such as cleaning and irrigation, as well as reducing water pressure and overexploitation of aquifers and preventing contamination of water bodies and diseases, which will have a positive effect in the environment and in the well-being of the communities. It is estimated that by 2030 there will be 9.2 billion cubic meters of wastewater; that, if treated and reused properly, could reduce the demand for potable water by 40% 4.

Liventia has on its tenure consortiums of microorganisms formulated exclusively for the treatment of residual waters that allow the biological processes in the treatment systems to be more efficient.

1. Cifras sobre la contaminación del agua
2. Aguas residuales y contaminación en México
3. Cifras reales de la contaminación del agua en México
4. Programa Mundial de Evaluación de los Recursos Hídricos (WWAP)