# Biosorption of Pb(II) Using Coffee Pulp as a Sustainable Alternative for Wastewater Treatment
## 1 Introduction  
Currently, heavy metals are considered as priority inorganic environmental pollutants, and these substances have become one of the most serious environmental problems that must be mitigated to protect humans and the environment [1]. There is a great need to reduce the pollutant load generated by these substances in water, soil and air, since they are not biodegradable and tend to bio-accumulate and bio-magnify in living organisms, they are highly toxic in cells, and in humans, they can be carcinogenic, mutagenic and teratogenic. Due to the above, heavy metals are present in the environmental policies of countries worldwide, with the purpose of improvement and meeting the Sustainable Development Goals (SDGs). As a contribution to this, Yale and Columbia Universities have formulated and divulged an Environmental Performance Index (EPI), which considers heavy metals as a category in its Environmental Health objective [2]. The EPI developed and published every two years by Yale and Columbia Universities--in collaboration with the World Economic Forum and the support of foundations such asMcCall MacBain and Mark T. [PERSON]--ranks 180 countries, considering 32 indicators and 11 environmental categories formulated until 2020, regarding two main objectives that go hand in hand with the SDGs: environmental health (with a weight of 40%) and ecosystem vitality (with a weight of 60%) [2]. This metric seeks to provide the countries with information about how close they are to the goals set out in their environmental policies, with the aim of improving them to become sustainable leaders. High scores, or close to 100, indicate commitments to protect public health, the preservation of natural resources and the reduction of the levels of emissions of greenhouse gasses (GHGs) from the different economic activities, while low values, or close to 0, are indicative of the need to make sustainability efforts, especially in the cleaning of air quality, the protection of biota and the reduction of GHGs [2]. EPI 2020 is based on the collection of data on 32 individual environmental performance metrics, with 11 problem categories: environmental health (air quality, sanitation and drinking water, heavy metals, solid waste management), and ecosystem vitality (biodiversity and habitat, ecosystem services, fisheries, climate change, pollutant emissions, water resources, agriculture). Likewise, the common scale assigned corresponds to 0 (indicating the worst performance) and 100 (indicating the best performance) [2]. In the case of heavy metals, the institutions mentioned previously consider the exposure to lead (Pb)--the metal of this research--in the Environmental Health objective, with a weight of 2% in the EPI. [PERSON] et al. [2] clarified that the selection of lead by the Yale and Columbia Universities team is due to the fact that this metal is the one that has been most studied by international organizations, such as the World Health Organization (WHO), and because Pb persists in several places in the world, it has led to a constant reduction in the pollution generated by it, as well as in the diseases that it produces. According to the Institute for Health Metrics and Evaluation, in 2015, Pb exposure accounted for nearly 0.5 million deaths and 9.3 million years of life lost (DALY) among adults aged 15 years and older, with higher incidence in developing regions [3]. It is one of the metals that most affects the child population and pregnant women [3,4]. At the environmental level, it can be found in air, dust, soil, water and in plants, due to the use of gasoline and emissions in industries that use it [3]. Figure 1 shows some countries, located by continent, according to their current position in relation to the lead exposure index score. According to Figure 1, among the leaders in sustainability were countries on the European continent, such as Finland and Denmark, as opposed to countries on the Asian and African continents, such as Afghanistan, Sudan and Egypt, which were near the end of the ranking.