This work was funded by CHERUB Environmental and Educational Projects Ltd.

1
A Novel Biological Phosphate Pump Julian Greaves,
Phil Haygarth Phil Hobbs Institute of Grassland
and Environmental Research,North Wyke Research
Station, Okehampton, Devon, EX20 2SB, UK.
Introduction
Abstract
An innovative manipulation of the standard
Enhanced Biological Phosphorus Removal (EBPR)
process configuration was used to increase the
concentration of (P) by three times. Four
replicate Sequencing Batch Reactors (SBRs) with a
working volume of 30 l, were used to treat an
influent stream of dilute pig slurry. We expect
that this system could be used to generate P
concentrations exceeding 100 mg l-1.
Currently ca. 120,000 t p.a. of P is collected as
manure in housed animal and dairy production
units in the UK. Of this ca. 26,000 t of P is
collected as slurry. Following a period of
storage, over 60 of this can be extracted by
dilution with water and is thereby potentially
available for recovery. This represents
approximately 70 of the UK non-agricultural P
requirement. Treatment of animal manures to
reduce their environmental impact is becoming
widespread and increasingly required under EU
legislation. The treatment system presented here
addresses the requirements of discharge consents
while simultaneously producing a clean source of
recoverable P. Such a system has the potential
to supply the P industry with a substantial
proportion of its overall needs. This system has
been developed as part of a research project
investigating P recovery from animal wastes.
However, the process uses a manipulation of
standard wastewater treatment procedures and is
therefore likely to be effective for a wide
range of influent sources including municipal
sewage.
Methods
Process description- Following the introduction
of a dilute influent, an anaerobic period
promotes the production of short chain fatty
acids (SCFAs) such as acetate. Uptake of SCFAs by
the phosphorus accumulating microflora (PAM)
promotes the release of P into the liquid phase
and enables excess uptake of P in the subsequent
aerobic phase (fig.1). Effluent discharge takes
place following a period of settlement, while P
remains trapped in the sludge solids. Subsequent
influent introduction provides the PAM with a
carbon source to promote the release of stored P.
Released P accumulates in the aqueous phase
together with the fresh influent P. Subsequent
cycles enable the stepwise accumulation of P in
the reactor until the PAMs capacity for P
storage is taken up. At this point the addition
of a carbon source such as acetate followed by an
extended anaerobic period promotes the release of
all stored P into a carbon depleted, denitrified
effluent. Samples were taken at the end of each
aerobic and anaerobic period for P, NO3 and NH4
analysis.
Fig. 1
Apparatus
Experimental parameters Influent P concentration
- 11.7 mg l-1 Influent quantity -
7.5 l P addition per cycle - 87.7 mg P
increase per cycle - 2.9 mg l-1
Results
Fig.2 Phosphorus behaviour over five cycles.
Fig.3 Phosphorus release after eleven cycles
Phosphorus was accumulated in the reactors from
11.7 mg l-1 in the influent to 29.6 mg l-1 in the
final effluent over eleven cycles.
This work was funded by CHERUB Environmental and
Educational Projects Ltd.