Biosorption of heavy metals from wastewater using Saccharomyces cerevisiae as a biosorbent: A mini review

Environmental pollution of heavy metals is increasingly becoming a problem and has become of great concern due to the adverse effects it is causing around the world. These inorganic pollutants are being discarded in our waters, soils and into the atmosphere due to the rapidly growing agriculture and metal industries, improper waste disposal, fertilizers and pesticides. This review shows how pollutants enter the environment together with their fate. Some metals affect biological functions and growth, while other metals accumulate in one or more different organs causing many serious diseases such as cancer. The pharmacokinetics and toxicological processes in humans for each metal is described. In summary, the review shows the physiological and biochemical effects of each heavy metal bioaccumulation in humans and the level of gravity and disquieting factor of the disease.

Environmental pollution has been on the rise in the past few decades owing to increased human activities on energy reservoirs, unsafe agricultural practices and rapid industrialization. Amongst the pollutants that are of environmental and public health concerns due to their toxicities are: heavy metals, nuclear wastes, pesticides, green house gases, and hydrocarbons. Remediation of polluted sites using microbial process (bioremediation) has proven effective and reliable due to its eco-friendly features. Bioremediation can either be carried out ex situ or in situ, depending on several factors, which include but not limited to cost, site characteristics, type and concentration of pollutants. Generally, ex situ techniques apparently are more expensive compared to in situ techniques as a result of additional cost attributable to excavation. However, cost of on-site installation of equipment, and inability to effectively visualize and control the subsurface of polluted sites are of major concerns when carrying out in situ bioremediation. Therefore, choosing appropriate bioremediation technique, which will effectively reduce pollutant concentrations to an innocuous state, is crucial for a successful bioremediation project. Furthermore, the two major approaches to enhance bioremediation are biostimulation and bioaugmentation provided that environmental factors, which determine the success of bioremediation, are maintained at optimal range. This review provides more insight into the two major bioremediation techniques, their principles, advantages, limitations and prospects.

As technology continues to advance, heavy metals in drinking water have exceeded recommended limits from regulators around the world. The main source of human exposure to heavy metals is from contaminated drinking water. The effects of drinking water contaminated with heavy metals, such as arsenic, lead, nickel, cadmium and mercury, have gradually caught the attention of the relevant departments and personnel. It is well known that occupational exposure to heavy metals occurs as a result of using these metals in a variety of industrial processes in and/or a variety of materials, including color pigments and alloys. A series of adverse effects on human metabolism has resulted from exposure to heavy metal-contaminated drinking water, which has been recorded from around the world. The general mechanism of heavy metal toxicity is through the production of reactive oxygen species, the appearance of oxidative damage, and subsequent adverse effects on health. Therefore, water contaminated with heavy metals causes high morbidity and mortality worldwide. In order to address concern regarding the health effects of different heavy metals, this paper reviews its sources, distribution and effects of heavy metal on human metabolism.HIGHLIGHTSThe accumulation of heavy metals such as lead, arsenic, mercury, cadmium and nickel will destroy the main metabolic process of human body.Redox reactions in biological systems are caused by carcinogenic metal ions such as nickel and arsenic. The free radicals produced by these reactions cause oxidative damage to proteins and DNA.The accumulation of heavy metals eventually produces reactive oxygen species that can cause oxidative stress, which may lead to the production of various diseases.