Wastewater treatment: Nature-based solutions

The different activities that we carry out in our daily life activities cause changes in the environment, including the aquatic environment. Used water (e.g. domestic and industrial) carries many different and undesirable/dangerous substances, due that it is usually designated as wastewater, and needs to be cleaned before it is released again in the environment. According to current estimates 80% of the world’s wastewater is not treated and returns to nature, causing serious problems for people’s health, and to the environment.

Although there are currently different technologies for wastewater treatment, this activity continues to be one of the main challenges worldwide. The water treatment can be carried out employing conventional and alternative technologies:

• Conventional treatments involve various processes. The number of processes and steps of cleaning depend on the degree of contamination and characteristics of the water. Conventional treatment is carried out in complex infrastructures and involves different technologies and equipment, therefore is usually very expensive and is suitable for medium and large cities. Conventional treatment  typically includes the following stages and processes; pre-treatment, primary treatment, secondary treatment and disinfection. See Fig.1.

Fig. 1. Phases of conventional wastewater treatment.

• Nature-based solutions (NBS): Comprise nature-based technologies as alternatives to conventional water treatment. NBS are currently being developed and innovated to be able to clean different types of water. These new technologies provide several advantages over conventional technologies, they are less expensive and integrate nature into human activities. The type of treatment to be used depends on the characteristics of the water to be treated, the quantity and the local environmental conditions. There are various nature-based solution technologies such as; treatment wetlands, stabilization ponds, multisoil layering and others (Figure 2).  One of the great advantages of nature-based treatments is that in addition to treating the water, they also generate benefits for the environment and society such as; increase in biodiversity, improve urban microclimates and generate green areas and recreational areas. They can be less expensive, or overall more cost-efficient than conventional systems.

Fig. 2. Classification of basic NBS groups for wastewater treatment

Without a doubt, NBS will contribute to solving these big challenges that we still face as a society.