Biosorption

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Biosorption is a physiochemical process that occurs naturally in certain biomass which allows it to passively concentrate and bind contaminants onto its cellular structure. [1] Biosorption can be defined as the ability of biological materials to accumulate heavy metals from wastewater through metabolically mediated or physico-chemical pathways of uptake. [2] Though using biomass in environmental cleanup has been in practice for a while, scientists and engineers are hoping this phenomenon will provide an economical alternative for removing toxic heavy metals from industrial wastewater and aid in environmental remediation.

Contents

Environmental uses

Pollution interacts naturally with biological systems. It is currently uncontrolled, seeping into any biological entity within the range of exposure. The most problematic contaminants include heavy metals, pesticides and other organic compounds which can be toxic to wildlife and humans in small concentration. There are existing methods for remediation, but they are expensive or ineffective. [3] However, an extensive body of research has found that a wide variety of commonly discarded waste including eggshells, bones, peat, [4] fungi, seaweed, crab shells, [5] yeast, baggase [6] and carrot peels [7] can efficiently remove toxic heavy metal ions from contaminated water. Ions from metals like mercury can react in the environment to form harmful compounds like methylmercury, a compound known to be toxic in humans. In addition, adsorbing biomass, or biosorbents, can also remove other harmful metals like: arsenic, lead, cadmium, cobalt, chromium and uranium. [8] [9]

The idea of using biomass as a tool in environmental cleanup has been around since the early 1900s when Arden and Lockett discovered certain types of living bacteria cultures were capable of recovering nitrogen and phosphorus from raw sewage when it was mixed in an aeration tank. [10] [11] This discovery became known as the activated sludge process which is structured around the concept of bioaccumulation and is still widely used in wastewater treatment plants today. It wasn't until the late 1970s when scientists noticed the sequestering characteristic in dead biomass which resulted in a shift in research from bioaccumulation to biosorption. [8]

Differences from bioaccumulation

Though bioaccumulation and biosorption are used synonymously, they are very different in how they sequester contaminants:

Biosorption is a metabolically passive process, meaning it does not require energy, and the amount of contaminants a sorbent can remove is dependent on kinetic equilibrium and the composition of the sorbents cellular surface. [9] Contaminants are adsorbed onto the cellular structure.

Bioaccumulation is an active metabolic process driven by energy from a living organism and requires respiration. [9] [12]

Both bioaccumulation and biosorption occur naturally in all living organisms [13] however, in a controlled experiment conducted on living and dead strains of bacillus sphaericus it was found that the biosorption of chromium ions was 13–20% higher in dead cells than living cells. [9]

In terms of environmental remediation, biosorption is preferable to bioaccumulation because it occurs at a faster rate and can produce higher concentrations. [9] Since metals are bound onto the cellular surface, biosorption is a reversible process whereas bioaccumulation is only partially reversible. [9]

Factors affecting performance

Since biosorption is determined by equilibrium, it is largely influenced by pH, the concentration of biomass and the interaction between different metallic ions. [3]

For example, in a study on the removal of pentachlorophenol (PCP) using different strains of fungal biomass, as the pH changed from low pH to high pH (acidic to basic) the amount of removal decreased by the majority of the strains, however one strain was unaffected by the change. [14] In another study on the removal of copper, zinc and nickel ions using a composite sorbent as the pH increased from low to high the sorbent favored the removal of copper ions over the zinc and nickel ions. [15] Because of the variability in sorbent this might be a drawback to biosorption, however, more research will be necessary.

Common uses

Even though the term biosorption may be relatively new, it has been put to use in many applications for a long time. One very widely known use of biosorption is seen in activated carbon filters. They can filter air and water by allowing contaminants to bind to their incredibly porous and high surface area structure. The structure of the activated carbon is generated as the result of charcoal being treated with oxygen. [16] Another type of carbon, sequestered carbon, can be used as a filtration media. It is made by carbon sequestration, which uses the opposite technique as for creating activated carbon. It is made by heating biomass in the absence of oxygen. The two filters allow for biosorption of different types of contaminants due to their chemical compositions—one with infused oxygen and the other without.

Figure 1. A Sorption Column Using Biosorbents. Sorption column.gif
Figure 1. A Sorption Column Using Biosorbents.

In industry

Many industrial effluents contain toxic metals that must be removed. Removal can be accomplished with biosorption techniques. It is an alternative to using man-made ion-exchange resins, which cost ten times more than biosorbents. [17] The cost is so much less, because the biosorbents used are often waste from farms or they are very easy to regenerate, as is the case with seaweed and other unharvested biomass.

Industrious biosorption is often done by using sorption columns as seen in Figure 1. Effluent containing heavy metal ions is fed into a column from the top. The biosorbents adsorb the contaminants and let the ion-free effluent to exit the column at the bottom. The process can be reversed to collect a highly concentrated solution of metal contaminants. The biosorbents can then be re-used or discarded and replaced.

Related Research Articles

<span class="mw-page-title-main">Water treatment</span> Process that improves the quality of water

Water treatment is any process that improves the quality of water to make it appropriate for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including being safely returned to the environment. Water treatment removes contaminants and undesirable components, or reduces their concentration so that the water becomes fit for its desired end-use. This treatment is crucial to human health and allows humans to benefit from both drinking and irrigation use.

<span class="mw-page-title-main">Environmental remediation</span> Removal of pollution from soil, groundwater etc.

Environmental remediation deals with the removal of pollution or contaminants from environmental media such as soil, groundwater, sediment, or surface water. Remedial action is generally subject to an array of regulatory requirements, and may also be based on assessments of human health and ecological risks where no legislative standards exist, or where standards are advisory.

<span class="mw-page-title-main">Bioremediation</span> Process used to treat contaminated media such as water and soil

Bioremediation broadly refers to any process wherein a biological system, living or dead, is employed for removing environmental pollutants from air, water, soil, flue gasses, industrial effluents etc., in natural or artificial settings. The natural ability of organisms to adsorb, accumulate, and degrade common and emerging pollutants has attracted the use of biological resources in treatment of contaminated environment. In comparison to conventional physicochemical treatment methods bioremediation may offer considerable advantages as it aims to be sustainable, eco-friendly, cheap, and scalable. Most bioremediation is inadvertent, involving native organisms. Research on bioremediation is heavily focused on stimulating the process by inoculation of a polluted site with organisms or supplying nutrients to promote the growth. In principle, bioremediation could be used to reduce the impact of byproducts created from anthropogenic activities, such as industrialization and agricultural processes. Bioremediation could prove less expensive and more sustainable than other remediation alternatives.

<span class="mw-page-title-main">Phytoremediation</span> Decontamination technique using living plants

Phytoremediation technologies use living plants to clean up soil, air and water contaminated with hazardous contaminants. It is defined as "the use of green plants and the associated microorganisms, along with proper soil amendments and agronomic techniques to either contain, remove or render toxic environmental contaminants harmless". The term is an amalgam of the Greek phyto (plant) and Latin remedium. Although attractive for its cost, phytoremediation has not been demonstrated to redress any significant environmental challenge to the extent that contaminated space has been reclaimed.

<span class="mw-page-title-main">Biofilter</span> Pollution control technique

Biofiltration is a pollution control technique using a bioreactor containing living material to capture and biologically degrade pollutants. Common uses include processing waste water, capturing harmful chemicals or silt from surface runoff, and microbiotic oxidation of contaminants in air. Industrial biofiltration can be classified as the process of utilizing biological oxidation to remove volatile organic compounds, odors, and hydrocarbons.

<span class="mw-page-title-main">Constructed wetland</span> Artificial wetland to treat municipal or industrial wastewater, greywater or stormwater runoff

A constructed wetland is an artificial wetland to treat sewage, greywater, stormwater runoff or industrial wastewater. It may also be designed for land reclamation after mining, or as a mitigation step for natural areas lost to land development. Constructed wetlands are engineered systems that use the natural functions of vegetation, soil, and organisms to provide secondary treatment to wastewater. The design of the constructed wetland has to be adjusted according to the type of wastewater to be treated. Constructed wetlands have been used in both centralized and decentralized wastewater systems. Primary treatment is recommended when there is a large amount of suspended solids or soluble organic matter.

<span class="mw-page-title-main">Industrial wastewater treatment</span> Processes used for treating wastewater that is produced by industries as an undesirable by-product

Industrial wastewater treatment describes the processes used for treating wastewater that is produced by industries as an undesirable by-product. After treatment, the treated industrial wastewater may be reused or released to a sanitary sewer or to a surface water in the environment. Some industrial facilities generate wastewater that can be treated in sewage treatment plants. Most industrial processes, such as petroleum refineries, chemical and petrochemical plants have their own specialized facilities to treat their wastewaters so that the pollutant concentrations in the treated wastewater comply with the regulations regarding disposal of wastewaters into sewers or into rivers, lakes or oceans. This applies to industries that generate wastewater with high concentrations of organic matter, toxic pollutants or nutrients such as ammonia. Some industries install a pre-treatment system to remove some pollutants, and then discharge the partially treated wastewater to the municipal sewer system.

<span class="mw-page-title-main">Mycoremediation</span> Process of using fungi to degrade or sequester contaminants in the environment

Mycoremediation is a form of bioremediation in which fungi-based remediation methods are used to decontaminate the environment. Fungi have been proven to be a cheap, effective and environmentally sound way for removing a wide array of contaminants from damaged environments or wastewater. These contaminants include heavy metals, organic pollutants, textile dyes, leather tanning chemicals and wastewater, petroleum fuels, polycyclic aromatic hydrocarbons, pharmaceuticals and personal care products, pesticides and herbicides in land, fresh water, and marine environments.

<span class="mw-page-title-main">Secondary treatment</span> Biological treatment process for wastewater or sewage

Secondary treatment is the removal of biodegradable organic matter from sewage or similar kinds of wastewater. The aim is to achieve a certain degree of effluent quality in a sewage treatment plant suitable for the intended disposal or reuse option. A "primary treatment" step often precedes secondary treatment, whereby physical phase separation is used to remove settleable solids. During secondary treatment, biological processes are used to remove dissolved and suspended organic matter measured as biochemical oxygen demand (BOD). These processes are performed by microorganisms in a managed aerobic or anaerobic process depending on the treatment technology. Bacteria and protozoa consume biodegradable soluble organic contaminants while reproducing to form cells of biological solids. Secondary treatment is widely used in sewage treatment and is also applicable to many agricultural and industrial wastewaters.

<span class="mw-page-title-main">Aerobic granular reactor</span>

Aerobic granular reactors (AGR) or Aerobic granular sludge (AGS) are a community of microbial organisms, typically around 0.5-3mm in diameter, that remove carbon, nitrogen, phosphorus and other pollutants in a single sludge system. It can also be used for wastewater treatments. Aerobic granular sludge is composed of bacteria, protozoa and fungi,which allows oxygen to follow in and biologically oxidize organic pollutants. AGS is a type of wastewater treatment process for sewages and/or industrial waste treatment. AGR was first discovered by UK engineers, Edward Ardern and W.T. Lockett who were researching better ways for sewage disposal. Another scientist by the name of Dr. Gilbert Fowler, who was at the University of Manchester working on an experiment based on aeration of sewage in a bottle coated with algae. Eventually, all three scientists were able to collaborate with one another to discover AGR/AGS.

<span class="mw-page-title-main">Phototrophic biofilm</span> Microbial communities including microorganisms which use light as their energy source

Phototrophic biofilms are microbial communities generally comprising both phototrophic microorganisms, which use light as their energy source, and chemoheterotrophs. Thick laminated multilayered phototrophic biofilms are usually referred to as microbial mats or phototrophic mats. These organisms, which can be prokaryotic or eukaryotic organisms like bacteria, cyanobacteria, fungi, and microalgae, make up diverse microbial communities that are affixed in a mucous matrix, or film. These biofilms occur on contact surfaces in a range of terrestrial and aquatic environments. The formation of biofilms is a complex process and is dependent upon the availability of light as well as the relationships between the microorganisms. Biofilms serve a variety of roles in aquatic, terrestrial, and extreme environments; these roles include functions which are both beneficial and detrimental to the environment. In addition to these natural roles, phototrophic biofilms have also been adapted for applications such as crop production and protection, bioremediation, and wastewater treatment.

<span class="mw-page-title-main">Sewage treatment</span> Process of removing contaminants from municipal wastewater

Sewage treatment is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable to discharge to the surrounding environment or an intended reuse application, thereby preventing water pollution from raw sewage discharges. Sewage contains wastewater from households and businesses and possibly pre-treated industrial wastewater. There are a high number of sewage treatment processes to choose from. These can range from decentralized systems to large centralized systems involving a network of pipes and pump stations which convey the sewage to a treatment plant. For cities that have a combined sewer, the sewers will also carry urban runoff (stormwater) to the sewage treatment plant. Sewage treatment often involves two main stages, called primary and secondary treatment, while advanced treatment also incorporates a tertiary treatment stage with polishing processes and nutrient removal. Secondary treatment can reduce organic matter from sewage,  using aerobic or anaerobic biological processes.

<span class="mw-page-title-main">Rhizofiltration</span>

Rhizofiltration is a form of phytoremediation that involves filtering contaminated groundwater, surface water and wastewater through a mass of roots to remove toxic substances or excess nutrients.

Electrokinetics remediation, also termed electrokinetics, is a technique of using direct electric current to remove organic, inorganic and heavy metal particles from the soil by electric potential. The use of this technique provides an approach with minimum disturbance to the surface while treating subsurface contaminants.

Copper zinc water filtration is a high-purity brass water filtration process that relies on the redox potential of dissolved oxygen in water in the presence of a zinc anode and copper cathode. It uses dissolved impurities within water as constituent substrate, which are reduced to more physiologically inert compounds.

Nanoremediation is the use of nanoparticles for environmental remediation. It is being explored to treat ground water, wastewater, soil, sediment, or other contaminated environmental materials. Nanoremediation is an emerging industry; by 2009, nanoremediation technologies had been documented in at least 44 cleanup sites around the world, predominantly in the United States. In Europe, nanoremediation is being investigated by the EC funded NanoRem Project. A report produced by the NanoRem consortium has identified around 70 nanoremediation projects worldwide at pilot or full scale. During nanoremediation, a nanoparticle agent must be brought into contact with the target contaminant under conditions that allow a detoxifying or immobilizing reaction. This process typically involves a pump-and-treat process or in situ application.

<span class="mw-page-title-main">Bioremediation of radioactive waste</span>

Bioremediation of radioactive waste or bioremediation of radionuclides is an application of bioremediation based on the use of biological agents bacteria, plants and fungi to catalyze chemical reactions that allow the decontamination of sites affected by radionuclides. These radioactive particles are by-products generated as a result of activities related to nuclear energy and constitute a pollution and a radiotoxicity problem due to its unstable nature of ionizing radiation emissions.

In 2015, 251 million tubes of toothpaste were sold in the United States. A single tube holds roughly 170 grams of toothpaste, so approximately 43 kilotonnes of toothpaste get washed into the water systems annually. Toothpaste contains silver nanoparticles, also known as nanosilver or AgNPs, among other compounds.

References

  1. ↑ Volesky, Bohumil (1990). Biosorption of Heavy Metals. Florida: CRC Press. ISBN   978-0849349171.
  2. ↑ Fouladi Fard, Reza.; Azimi, A.A.; Nabi Bidhendi, G.R. (April 2011). "Batch kinetics and isotherms for biosorption of cadmium onto biosolids". Desalination and Water Treatment. 28 (1–3): 69–74. doi:10.5004/dwt.2011.2203.
  3. 1 2 Ahalya, N.; Ramachandra, T.V.; Kanamadi, R.D. (December 2003). "Biosorption of Heavy Metals". Research Journal of Chemistry and Environment. 7 (4). Archived from the original on 2013-02-21. Retrieved 2013-01-09.
  4. ↑ Schildmeyer, A.; Wolcott, M.; Bender, D. (2009). "Investigation of the Temperature-Dependent Mechanical Behavior of a Polypropylene-Pine Composite". J. Mater. Civ. Eng. 21 (9): 460–6. doi:10.1061/(ASCE)0899-1561(2009)21:9(460).
  5. ↑ Aris, A. Z.; Ismail, F. A.; Ng, H. Y.; Praveena, S. M. (2014). "An Experimental and Modelling Study of Selected Heavy Metals Removal from Aqueous Solution Using Scylla serrata as Biosorbent". Pertanika Journal of Science & Technology. 22 (2): 553–566.
  6. ↑ Tewari, N.; Vasudevan, P. (July 2020). "Profile of parameters affecting adsorption of Hexavalent Chromium on low-cost adsorbent- The raw baggase". American Journal of Environmental Biology. 1: 34–49. doi: 10.47610/ajeb-2020-a1v4 . S2CID   241146463.
  7. ↑ Bhatti, Haq N.; Nasir, Abdul W.; Hanif, Muhammad A. (April 2010). "Efficacy of Daucus carota L. waste biomass for the removal of chromium from aqueous solutions". Desalination. 253 (1–3): 78–87. doi:10.1016/j.desal.2009.11.029.
  8. 1 2 Lesmana, Sisca O.; Febriana, Novie; Soetaredjo, Felycia E.; Sunarso, Jaka; Ismadji, Suryadi (April 2009). "Studies on potential applications of biomass for the separation of heavy metals from water and wastewater". Biochemical Engineering Journal. 44 (1): 19–41. doi:10.1016/j.bej.2008.12.009.
  9. 1 2 3 4 5 6 Velásquez L, Dussan J (August 2009). "Biosorption and bioaccumulation of heavy metals on dead and living biomass of Bacillus sphaericus". J. Hazard. Mater. 167 (1–3): 713–6. doi:10.1016/j.jhazmat.2009.01.044. PMID   19201532.
  10. ↑ Sawyer, Clair N. (February 1965). "Milestones in the Development of the Activated Sludge Process". Journal of the Water Pollution Control Federation. 37 (2): 151–162. JSTOR   25035231.
  11. ↑ Alleman, James E.; Prakasam, T.B.S. (May 1983). "Reflections on Seven Decades of Activated Sludge History". Journal of the Water Pollution Control Federation. 55 (5): 436–443. JSTOR   25041901.
  12. ↑ Vijayaraghavan K, Yun YS (2008). "Bacterial biosorbents and biosorption". Biotechnol. Adv. 26 (3): 266–91. doi:10.1016/j.biotechadv.2008.02.002. PMID   18353595.
  13. ↑ Chojnacka K (April 2010). "Biosorption and bioaccumulation—the prospects for practical applications". Environ Int. 36 (3): 299–307. doi:10.1016/j.envint.2009.12.001. PMID   20051290.
  14. ↑ Mathialagan T, Viraraghavan T (January 2009). "Biosorption of pentachlorophenol from aqueous solutions by a fungal biomass". Bioresour. Technol. 100 (2): 549–58. doi:10.1016/j.biortech.2008.06.054. PMID   18722113.
  15. ↑ Bayramoğlu G, Yakup Arica M (January 2009). "Construction a hybrid biosorbent using Scenedesmus quadricauda and Ca-alginate for biosorption of Cu(II), Zn(II) and Ni(II): kinetics and equilibrium studies". Bioresour. Technol. 100 (1): 186–93. doi:10.1016/j.biortech.2008.05.050. PMID   18632265.
  16. ↑ "What is activated charcoal and why is it used in filters?". How Stuff Works. April 2000. Retrieved 2010-03-02.
  17. ↑ "What is Biosorption". BV SORBEX, Inc. Retrieved 2010-03-02.
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