Biological
Phosphorus Removal
1/30/2006
Biological Phosphorus Removal
1
Phosphorus
„ Phosphorus is an essential nutrient for plants and animals in the
form of ions PO43- and HPO42„ It is a part of DNA-molecules, molecules that store energy (ATP and
ADP) and fats of cell membranes. Phosphorus is also a building
block of certain parts of the human and animal body, such as the
bones and teeth.
„ Can be found on earth in water, soil and sediments.Cannot be found
in air in the gaseous state because phosphorus is usually liquid at
normal temperatures and pressures. It is mainly cycling through
water, soil and sediments. In the atmosphere phosphorus can
mainly be found as very small dust particles.
„ Polyphosphates are used industrially to bind metals, such as in
some laundry detergents
1/30/2006
Biological Phosphorus Removal
2
„ Phosphorus and nitrogen in water resources stimulate growth
of algae and other photosynthetic aquatic life, which lead to
accelerated eutrophication of lakes and other natural waters
„ Eutrophication causes :
„
„
„
„
„
Increased water purification costs ,
Interference with the recreational value of water,
Health risks to both humans and livestock.
excessive loss of oxygen resources, and
undesirable changes in aquatic populations.
„ The EU Urban Wastewater Treatment Directive will require an
effluent standard of no more than 1mg/l phosphate for large
treatment works
1/30/2006
Biological Phosphorus Removal
3
1/30/2006
Biological Phosphorus Removal
Toba
Lake in North-Sumatera,
Indonesia
4
1/30/2006
Biological
Phosphorus Removal
Eutrophication
beginning in Toba
Lake
5
1/30/2006
Biological Phosphorus Removal
6
1/30/2006
Biological Phosphorus Removal
7
1/30/2006
Biological Phosphorus Removal
8
„ Biological Phosphorus removal (BPR) from domestic and industrial
wastewater is a key factor in preventing eutrophication of surface
watersand one of the most economical and efficient methods for
phosphorus removal.
„ BPR is achieved by :
„
growing microorganisms that are capable of storing phosphorus
intracellularly as polyphosphate.
„
The growth of phosphorus-accumulating organisms (PAOs) is
favored by subjecting the activated sludge to a cycle of
anaerobic and aerobic conditions
„
Phosphorus is then removed by wasting excess sludge.
1/30/2006
Biological Phosphorus Removal
9
„ Parameters that have been used to
evaluate the feasibility of BPR include :
„ ratios
of biochemical oxygen demand
(BOD5) or chemical oxygen demand
(COD) to phosphorus (P)
„ total Kjeldahl nitrogen (TKN) to COD.
1/30/2006
Biological Phosphorus Removal
10
Process
„ Enhanced biological phosphorus removal (EBPR)
from wastewater involves mixing the influent
wastewater with settled microbial biomass enters the
anaerobic selector where chemically bound oxygen in
the form of nitrates is removed
„ The microorganisms have the ability to store energy
in the form of polyphosphate chemical bonds .Some
of these microorganisms are called polyphosphate
accumulating organisms (PAOs)
1/30/2006
Biological Phosphorus Removal
11
„ In the anaerobic zone, where substrate (BOD) concentration is
high, the absence of oxygen causes the micro organisms to
release the stored intracellular polyphosphates by decomposition
to simple orthophosphate
1/30/2006
Biological Phosphorus Removal
12
„ The decomposition of polyphosphate to orthophosphate results in an
increase of soluble phosphorus in the mixed liquor and also releases energy.
The energy is used by the micro organisms to transport soluble BOD through
the cell wall and to store the soluble BOD inside the cell .Thus, the BOD
concentration in the mixed liquor is reduced without the use of oxygen
„ In the oxic phases of the process, the organisms, in the presence of
dissolved oxygen :
„ convert the stored BOD to CO2, water,
„ and increased cell mass
1/30/2006
Biological Phosphorus Removal
13
„
A portion of the energy from this reaction then goes to
recreating the intracellular polyphosphate using the
orthophosphate released in the anaerobic zone
„ Since new cells are grown, the amount of phosphate removed
from solution is greater than that previously solubilized in the
anaerobic zone, thus providing for a net phosphate removal
„ Phosphorus is removed from the system as a fixed biological
material in the waste sludge. The amount of phosphorus in the
sludge will be dependent upon the amount of BOD and
phosphate in the influent and the volume of sludge produced.
1/30/2006
Biological Phosphorus Removal
14
The phosphorus cycle
1/30/2006
Biological Phosphorus Removal
15
Polyphosphate
„ PolyP is readily degraded by the action of a number of
enzymes. PolyP may subsitute for ATP in various kinase reactions
with, AMP, ADP and glucose and for other sugars, nucleosides, and
proteins (Kornberg et al., 1999) (Kulaev & Kulakovskaya, 2000).
„ Inorganic polyphosphate (polyP) is a linear, unbranched polymer of
orthophosphate residues linked by phosphoanhydride bonds
„ PolyP is widespread in bacteria and yeasts and has been found in
plant and animal cells PolyP was first found in yeast cells by
Liebermann (1888).
1/30/2006
Biological Phosphorus Removal
16
1/30/2006
Biological Phosphorus Removal
17
Microorganisms in BPR process
„ No polyphosphate-accumulating organisms isolated from enhanced biological
phosphorus removal have been able to depict the general metabolic behavior
observed for activated sludge . Among them are :
„
„
„
„
Acinetobacter spp
Lampropedia spp .
Microlunatus phosphovorus , and
Tetrasphaera spp .
„ By using a clone library and fluorescent in situ hybridization techniques, it was
shown that bacteria related to the Rhodocyclus group ("Candidatus
accumulibacter phosphatis") were widespread in laboratory-scale enhanced
biological phosphorus removal reactors, with extremely efficient P removal
1/30/2006
Biological Phosphorus Removal
18
•Some microorganisms store phosphate as polyphosphate.
•Research now at pilot scale with Severn Trent Water Ltd, Yorkshire Water plc,
and Northern Ireland Water Service.
1/30/2006
Biological Phosphorus Removal
19
Biological phosphorus removal by a
pure culture of Lampropedia spp
„ Lampropedia spp. is a gram-negative, Neisser-
positive coccus that was isolated from EBPR
(enhanced biological phosphate removal) activated
sludge laboratory plants operating on dairy and
piggery wastewaters.
Lampropedia spp. in pure
culture (Blu Nilo stain)
Stante L., Cellamare C. M., Malaspina F., Bortone G.
and Tilche A.
ENEA - Sezione Depurazione e Ciclo dell'Acqua - Via
Martiri di Monte Sole, 4 I-40129 Bologna - Italy
1/30/2006
Biological Phosphorus Removal
20
A bacterium belonging to the genus Lampropedia isolated from EBPR activated
sludge has been studied for its capacity of performing enhanced biological phosphate
removal. Acetate uptake, PHB formation and phosphate release in anaerobic
conditions as well as phosphate uptake and PHB consumption in aerobic conditions
have been recorded. but cell phosphorus fractionation analyses demonstrated a
cyclic increase and decrease of the poly-P fraction from aerobic to anaerobic
conditions. All these evidences allow to conclude that Lampropedia spp. can be
classified as a poly-P accumulating microorganism.
Lampropedia spp. in activated sludge (Neisser stain, white bar is 10 µm)
1/30/2006
Biological Phosphorus Removal
21