Cellulose emerges as an alternative for the treatment of water contaminated with heavy metals due to its abundant biomass and its proven potential in the adsorption of pollutants. The aquatic plant Eichhornia crassipes is an option as raw material in the contribution of cellulose due to its enormous presence in contaminated wetlands, rivers, and lakes. The efficiency in the removal of heavy metals is due to the cation exchange between the hydroxyl groups and carboxyl groups present in the biomass of E. crassipes with heavy metals. Through different chemical and physical transformations of the biomass of E. crassipesThe objective of this review article is to provide a discussion on the different mechanisms of adsorption of the biomass of E. crassipes to retain heavy metals and dyes. In addition to estimating equilibrium, times through kinetic models of adsorption and maximum capacities of this biomass through equilibrium models with isotherms, in order to design one biofilter for treatment systems on a larger scale represented the effluents of a real industry.

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The aim of this work is to design a fixed-bed column with vegetal biomass of Eichhornia crassipes and the process of recycling it for treatment via the adsorption of water loaded with chromium (VI). In the first stage, the relationship between the fixed-bed density and the microparticle density is calculated, giving a model for the design of the fixed bed. Using this model, two systems for the treatment of Cr (VI)-contaminated water were designed and built. The vegetable biomass at three particle diameters of 0.212 mm, 0.30 mm and 0.45 mm was evaluated in the removal of Cr (VI) from water using the designed fixed-bed systems, giving the best removal of Cr (VI) with the lowest size particles and allowing the validation of the proposed model with the Thomas model. The incorporation of iron into the biomass allowed for the treatment of near 2.0 L of polluted solution, removing around 90% of Cr (VI), while it was only possible to treat nearly 1.5 L when using raw biomass, removing around 80% of Cr (VI). The recycling of the biomass was achieved via the elution of Cr (VI) with EDTA, permitting the reuse of the material for more than five treatment cycles.

Ground-level ozone is one of the most widespread pollutants in the world. Millions of people are exposed to unhealthy levels of ozone air pollution on a daily basis. Often called 'smog', ozone is harmful to breathe and is associated with the development and exacerbation of pulmonary and cardiovascular disease. Scientists have studied the effects of ozone exposure on human health for decades. Hundreds of research studies have confirmed that ozone harms the human body when inhaled at levels currently found in many cities and countries. Ozone is a gas molecule composed of three oxygen atoms that is formed by a reaction between atmospheric oxygen and organic volatile compounds from vehicle and industrial emissions in the presence of sunlight. When inhaled, ozone aggressively attacks lung tissue and triggers systemic inflammation that can result in a series of health complications, ranging from inflammation and injury of the airways to alterations of vital functions at the cardiovascular, immune, endocrine and neurological levels and even death. In women, exposure to ozone can also affect fertility, cause pregnancy complications and alter fetal development. It has also been noted that susceptibility to ozone varies with age, gender and health status and studies have indicated that sex hormones can contribute to the damaging effects of ozone in the lung. Patients suffering from inflammatory lung disease, including asthma, bronchitis, chronic obstructive pulmonary disease and lung infection, are at significantly higher risk for negative health effects associated with ozone exposure. Numerous studies in cells and animal models have helped to elucidate some of the mechanisms of ozone toxicity and have identified cell receptors and inflammatory cytokines that activate the inflammatory response upon ozone exposure. These have also provided information for environmental agencies to control emissions and warn the population about unhealthy levels. In this chapter, we summarize the known effects of ozone exposure on human health, as well as the main results from clinical and animal studies testing ozone exposure at different doses. We also discuss current policies and regulations aimed to control emissions and potential harm to various populations. A better understanding of the negative effects of ozone exposure on human health and of the mechanisms associated with its toxicity will likely inform policy makers to introduce new guidelines to control environmental emissions and will allow for the development of strategies for symptom management and potential therapeutics for different individuals exposed to unhealthy ozone levels.