Enhanced biological phosphorus removal (EBPR) is a

sewage treatment Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable for discharge to the surrounding e ...

configuration applied to

activated sludge The activated sludge process is a type of biological wastewater treatment process for treating sewage or industrial wastewaters using aeration and a biological floc composed of bacteria and protozoa. It uses air (or oxygen) and microorganism ...

systems for the removal of

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...

. The common element in EBPR implementations is the presence of an

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...

tank ( nitrate and

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

are absent) prior to the

aeration Aeration (also called aerification or aeriation) is the process by which air is circulated through, mixed with or dissolved in a liquid or other substances that act as a fluid (such as soil). Aeration processes create additional surface area in ...

tank. Under these conditions a group of

heterotroph A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...

, called

polyphosphate-accumulating organisms Polyphosphate-accumulating organisms (PAOs) are a group of bacteria that, under certain conditions, facilitate the removal of large amounts of phosphorus from wastewater in a process, called enhanced biological phosphorus removal (EBPR). PAOs acc ...

(PAO) are selectively enriched in the bacterial community within the activated sludge. In the subsequent aerobic phase, these bacteria can accumulate large quantities of

polyphosphate Polyphosphates are salts or esters of polymeric oxyanions formed from tetrahedral PO4 (phosphate) structural units linked together by sharing oxygen atoms. Polyphosphates can adopt linear or a cyclic ring structures. In biology, the polyphosphate e ...

within their

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

s and the removal of phosphorus is said to be ''enhanced''. Generally speaking, all bacteria contain a fraction (1-2%) of

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

in their biomass due to its presence in cellular components, such as

membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. ...

phospholipids and DNA. Therefore, as bacteria in a wastewater treatment plant consume nutrients in the wastewater, they grow and phosphorus is incorporated into the bacterial biomass. When PAOs grow they not only consume phosphorus for cellular components but also accumulate large quantities of polyphosphate within their cells. Thus, the phosphorus fraction of phosphorus accumulating biomass is 5-7%. In mixed bacterial cultures the phosphorus content will be maximal 3 - 4 % on total organic mass. If additional chemical precipitation takes place, for example to reach discharge limits, the P-content could be higher, but that is not affected by EBPR. This biomass is then separated from the treated (purified) water at end of the process and the phosphorus is thus removed. Thus if PAOs are selectively enriched by the EBPR configuration, considerably more phosphorus is removed, compared to the relatively poor phosphorus removal in conventional activated sludge systems.

References

External links

Handbook Biological Waste Water Treatment
- Principles, Configuration and Model
EPBR Metagenomics: The Solution to Pollution is Biotechnological Revolution
- A Review from the Science Creative Quarterly
Website of the Technische Universität Darmstadt and the CEEP about Phosphorus Recovery
{{DEFAULTSORT:Enhanced Biological Phosphorus Removal Biotechnology Waste treatment technology

See also

References

Further reading

External links