Biological phosphorus removal is very essential to reduce the nutrient load by some bacteria called phosphate accumulating organisms.

1. BIOLOGICAL PHOSPHORUS REMOVAL
FOR WASTE WATER TREATMENT
ANJALI T.B
SES, CUSAT

2. INTRODUCTION
Presence of nutrients like nitrogen & phosphorus in waste water effluents
and their impacts on natural water bodies are of major concern.
With the recent evidence that the anthropogenic phosphorus addition in
microorganisms in milligram per litre level can trigger algal growth.
Chemical & biological means are adopted to remove them.
Biological phosphorus removal process is popular over chemical means, for
it’s simplicity, economy & various environmental benefits.
This process relies on enhancing ability of organisms to uptake more
phosphorus into their cell.

3. These processes are often referred to as “ Enhanced Biological
Phosphorus Removal (EBPR) process.
It is considered to be a cost effective and environmentally
sustainable alternative to chemical treatment.
It also have limited space and multi-functioning systems.
There is a growing understanding of the biochemical mechanisms
associated with luxury phosphorus uptake, Which early upon
Phosphorus Accumulating Organisms( PAO) for EBPR.
There are some operating conditions like;
Prerequisites for metabolism such as C, Glucose & electron acceptor
are being adjusted to promote the growth and proliferation of PAOs.

4. Identification of PAO
Biological P-removal primarily occurs via the accumulation of P
by microbes (Luxury uptake).
P- accumulation is as Polyphosphate as an energy reserve for
maintenance or to provide a competitive advantage over ordinary
heterotrophs.
Candidatus Accumulibacter phosphatis (Accumulibacter) is the
widely used PAO.
Acinetobacter species, were reported to be the organisms
primarily responsible for EBPR.

5. Candidatus Accumulibacter phosphatis
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Betaproteobacteria
Order: Unclassified
Family:
Candidatus
Accumulibacter
Candidatus Accumulibacter
phosphatis (blue cells)

6. Acinetobacter
Scientific classification
Domain: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Pseudomonadales
Family: Moraxellaceae
Genus: Acinetobacter
Acinetobacter baumannii

7. Other putative PAOs found in varying low levels at P- removal
wastewater treatment plants are;
Pseudomonas sp.
Pseudomonas
P. aeruginosa colonies on an agar plate
Scientific classification
Domain: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Pseudomonadales
Family: Pseudomonadaceae
Genus: Pseudomonas

8.  Paracoccus sp.
Paracoccus denitrificans
Scientific classification
Domain: Bacteria
Phylum: Proteobacteria
Class: Alphaproteobacteria
Order: Rhodobacterales
Family: Rhodobacteraceae
Genus: Paracoccus
Species: P. denitrificans
Binomial name
Paracoccus denitrificans

9. Enerococcus sp.
Class: Bacilli
Scientific name: Enterococcus
Order: Lactobacillales
Division: Firmicutes
Higher classification: Enterococcaceae
Lower classifications: Enterococcus faecalis

10. BIOLOGICAL P-REMOVAL
Soluble & Particulate phosphorus.
The treatment process can be designed to promote the
growth of PAOs.
PAOs convert available organic matter to PHAs.
PHAs: Polyhydroxy alkanoates are linear polyesters
produced in nature by bacterial fermentation of sugar or
lipids.

11. TREATMENT PROCESSES
Integrated fixed film activated sludge process.
Sequential batch reactor process.
Step feed process.
Moving bed biofilm reactor process.
Membrane biological reactor process.
Oxidation Ditch process.

12. INTEGRATED FIXED FILM ACTIVATED SLUDGE
PROCESS (IFAS)

13. The IFAS process is a combination of the fixed-film and the
suspended activated sludge processes.
 In general, the addition of media to the aeration basins makes
it possible for nitrifying sludge ages to be attained in
considerably smaller basin volume than required for a comparable
single-stage activated sludge nitrification process.
The added media provides surface area for the growth of
microbes, and, in combination with the MLSS, the desired
nitrification.
 The result is an equivalent MLSS concentration upwards of
6,000 mg/L.
 The attached growth, however, does not impose excessive solids
loadings on the final clarifiers, since the growth remains in the
aeration basin.

15. SEQUENTIAL BATCH REACTOR
(SBR) PROCESS

16. STEP FEED PROCESS
Continuous flow process.
Influent flow is split to several feed locations.
Recycle sludge stream is sent to the beginning.
Higher solid retention time is achieved providing enhanced treatment.
Phosphorus removal is limited.

17. MOVING BED BIOFILM REACTOR PROCESS
(MBBR)
Direct derivative of fixed film
activated sludge process.
HDPE carrier elements are used.
Provides sites for bacteria
attachment.
Allows higher concentration of
active biomass.
More treatment capacity.
Phosphorus removal requires
additional stages.

18. CARRIERS USED IN MBBR

19. MEMBRANE BIOLOGICAL REACTOR PROCESS
(MBR)
Consists of separate aeration tanks
and membrane filtration tanks.
The membrane elements separate
solids from the treated effluent.
Excess solids are wasted directly
from the aeration tanks.
Membranes vary from hollow tube
filters to flat panels.
Require several cleaning cycles.

20. OXIDATION DITCH PROCESS

22. MECHANISM IN P- REMOVAL
The phosphorus in the waste water is merged into cell biomass,
which is later removed as an end product of sludge wasting.
The reactor configuration consist of an anaerobic tank and an
activated sludge tank.
Retention time in the anaerobic tank is about 0.50 to 1.00 hrs.

23. UNDER ANAEROBIC CONDITIONS
PAO blend in fermentation products into storage products within
the cells with the associated release of phosphorus from stored
phosphates.
Acetate is produced by fermentation.
Which is dissolved degradable organic material that can be easily
integrated by the biomass.
Energy available from stored polyphosphate, the PAO adapt
acetate & produce intracellular poly hydroxy butyrate(PHB) storage
products.
The PHB content in the PAO increases as the polyphosphate
decreases.

25. IN THE AEROBIC ZONE
Energy is produced by the oxidation of storage products &
polyphosphate storage within the cell increases.
Stored PHB is processed , providing energy from oxidation & C
for new cell growth.
The energy released from PHB oxidation is used to form
polyphosphate bonds in the cell storage.

26. The soluble orthophosphate is removed from the solution &
combined into polyphosphate within the bacterial cell.
PHB utilization also enhances cell growth and this new
biomass with high polyphosphate storage accounts for P
removal.
As a portion of the biomass is wasted the stored phosphorus
is removed from the bio-treatment reactor for ultimate
disposal with the waste sludge.

28. TRADITIONAL EBPR SYSTEMS & RECENT ENHANCEMENTS
EBPR has traditionally been applied with in conventional activated
sludge (CAS) systems.
The level of biological P-removal is directly proportional to the number
of PAO present in the system.
Recent applications of EBPR include incorporation in membrane
bioreactors (MBR), Granular Sludge Reactors & Sequencing Batch
Biofilm Reactor (SBRs).

29. Inclusion of EBPR in MBRS, whether SBRs or continuous- flow,
has proven successful in achieving high levels of P- removal from
MWW.
Novel technologies offer potential for high levels of P-removal with
some even achieving efficient P-removal over sustained periods of
time at various scales.
ALGAE-BASED & HYBRID TREATMENT OPTIONS
The use of microalgae systems for the treatment of wastewater is
now well established.
But it’s full-scale applications for nutrient removal is more limited.

30. MECHANISMS OF ALGAL P-REMOVAL
P is an essential nutrient for algal growth.
Under some circumstances, P is taken up as polyphosphate granules for
use as a growth reserve for when there is a lack of P in the environment.
Where, inorganic orthophosphate is unavailable, algae will uptake
organic P, converting to orthophosphate at the cell surface via the
enzyme phosphatase.
Algal treatment solutions are typically either closed or open suspended
systems, or biofilm systems, most commonly using flat-bed or tubular
orientation.

32. APPLICATION OF ALGAL P- SYSTEMS
The green microalga Scenedesmus sp. and Chlorella sp. are known to
carry out consequential luxury P uptake in the natural environment.
high levels (up to 90%) of P-removal has been achieved by the
immobilization of these microalgae on synthetic substrate, either sheets
or as beads.
Micro-algal biofilm photo-bioreactors have also shown effective removal
(97% Total P-removal).
An osmotic membrane photo-bioreactor is a further enhancement of
the membrane photo-bioreactor, developed with the specific intention of
reducing membrane fouling.

34. THANK YOU