Heavy Metal Pollutants in Wastewater Effluents: Sources, Effects and Remediation

Abstract

Abstract:Heavy metals, also known as trace metals, are one of the most persistent pollutants in wastewater. The discharge of high amounts of heavy metals into water bodies leads to several environmental and health impacts. The exposure of humans to heavy metals can occur through a variety of routes, which include inhalation as dust or fume, vapourisation and ingestion through food and drink. Some negative impacts of heavy metals to aquatic ecosystems include death of aquatic life, algal blooms, habitat destruction from sedimentation, debris, increased water flow, other short and long term toxicity from chemical contaminants. Abundant amounts of heavy metals present in soils cause reduction in quality and quantity of food preventing plants' growth, uptake of nutrients, physiological and metabolic processes. Severe effects on animals may include reduced growth and development, cancer, organ damage, nervous system damage, and in extreme cases, death. To help mitigate the negative impacts of heavy metals on the health of humans, animals and the environment, a variety of remediation processes exists. These remediation processes are broadly classified into chemical and biological, although the latter is advocated in recent years. Biological remediation processes (microbial remediation and phytoremediation) are indicated to be very effective in the treatment of heavy metal pollutants in wastewater. Microbial remediation is the restoration of the environment and its quality using microorganisms, such as bacteria, fungi, protozoan and algae while phytoremediation is the use of plants to degrade or accumulate toxic metals, thereby leading to a reduction in the bioavailability of the contaminant in the soil or water. This paper was therefore aimed at reviewing the sources, impacts and remediation processes for heavy metals in wastewater.

Review of Eco-Friendly Biochar Used in the Removal of Trace Metals on Aqueous Phases

“…Major anthropogenic activities or source of trace metals in aqueous environment especially land field waste water, water bodies among others in both developed and developing countries include domestic and industrial waste, textiles activities, mining and extraction operations, metal finishing and electroplating, landfill leachates and nuclear power [89,90]. Metal finishing and electroplating contribute to release of toxic trace metal into aqueous environment.…”

“…Untreated waste found in land fields may contain trace metal that usually leach into liquid ponds and leachates released into receiving aqueous environment that can cause environmental impact and human health problems [89]. Trace metal contaminants continue to serve as a major threat to aqueous environment and plants.…”

“…Generally, the inhalation of vapours and ingestion of aluminium, arsenic, cadmium, copper, lead, mercury and zinc can result in poisoning, diarrhoea, gastrointestinal disorders, stomatitis, tremor, hemoglobinuria triggering a rust-red colour to human stool, ataxia, vomiting and convulsion, depression and pneumonia and paralysis [103]. Trace metals become only toxic in human systems as results of inability to metabolise and synthesise, and accordingly accumulate in human body particular the soft tissues [89]. For instance, lead has proven to be the number one health threat to children as its effects (child"s growth, cause learning disabilities and damage the nervous system) can last a lifetime and has now been linked to crime and anti-social behaviour in children [104].…”

Updates on Glucose 6-Phosphate Dehydrogenase (G6PD): From Prokaryotes to Human

“…Several methods have been employed in managing wastewater effluents in the society, however, with the most effective means been microbial remediation; several setbacks are however still encountered [144]. Among several impediments, a vital issue is the brief life span of microbes employed in the remediation process [144].…”

Quality Assessment of Waterside River, Ogbor Hill Aba 4: Effect of Three-Point Samples on Hepatic Histo-Morphology and Some Seric Bio-Functional Indicators of Wistar Rats

“…Water pollution resulting from environmental factors as well as human and industrial activities could be worsened with poor urban sewage system and consequent seepage of wastes to streams [4] along with heavy metals can enter streams. Heavy metals are not biodegradable hence could bioaccumulate to exert varied toxic influences in animals, aside compromising the water quality or potability [5][6][7][8][9][10] . Thus, the seepage of heavy metals into streams is a significant environmental problem hence worrisome [11,12] .…”