TY - BOOK
T1 - Waste water treatment by multi-stage biofilm processes
T2 - Results of the VESITURVA project
A2 - Mononen, Tiina
A2 - Vikman, Minna
N1 - Project code: 82607
PY - 2013
Y1 - 2013
N2 - Municipal and industrial waste waters in Finland are
treated before their release into the environment. New
legislation also requires that waste waters from all
households with running water are treated before release,
whereas the methods for treatment may vary. In the
Tekes-Symbio project VESITURVA research groups at the
University of Helsinki, VTT, Tampere University of
Technology and Lahti University of Applied Science, in
collaboration with companies in the field and municipal
stakeholders, pooled their resources in an effort to
study and improve waste water treatment.
In the case of household waste waters, minimum removal
requirements exist only for the bulk components, organic
matter (BOD, COD), nitrogen, and phosphorus. While we
also monitored the removal of these components in
VESITURVA, the main focus was on micropollutants
(pollutants that exist in waste water in ng per litre to
µg per litre concentrations, for example hormone
disruptors, farmaceuticals, musks, components of personal
care products etc.) - how they behave and how their
removal can be improved.
In VESITURVA we tested waste water treatment methods that
are based on biofilms colonising the surfaces of matrix
materials using multi-phase water treatment systems,
where the water passes through two or three reactors. The
model substances for the micropollutant removal process
were Bisphenol A (BPA), a component used in the plastics
industry, and the commonly used polycyclic musk compound
HHCB. Two different types of reactors were used for
studying the effect of biofilm activity: Rotating Bed
Bioreactors (RBBR), where the biofilm develops on plastic
beads with a large surface area, and Fixed Bed
Bioreactors (FBBR), where wood chips were used as the
support. In both cases a continuous or semicontinuous
flow of waste water passed through the reactors. In the
RBBR set-up, municipal waste water was led through a
three-phase treatment process, while in the FBBR
artificial grey water was treated in a two-phase process.
In both processes, the removal of the bulk components was
good, and substantial reductions were also achieved in
the case of the model micropollutants. Multi-stage
biofilm reactors seemed to be efficient at removing BPA
and musk HHCB from waste water. Major parts of the
micropollutants were already removed in the first
reactors but the model of sequential reactors enhanced
the removal of both BPA and HHCB. Diversity of bacterial
communities decreased as a function of time suggesting
that the bacterial communities in the reactors became
specialized over time. The same bacterial groups were
dominant in all sequential reactors, but differences were
observed at genus taxonomic level. Also, the microbial
diversity was similar to that seen earlier studies of
waste water treatment microbiology. Carrier material
(polyethylene, wood chips) affected the biofilm community
profile in FBBR.
The performance of FBBR in grey water purification was
evaluated in field conditions when the reactor was
installed in a detached house. The nitrogen removal
efficacy of the reactor was very good and the maximum
nitrogen removal efficiency in the system was 84%.
Nitrogen removal in grey water treatment system was
verified by an evaluation of the abundance of
denitrifying microbes. The performance of the grey water
treatment system was returned to the original level in
1-2 weeks after the replacement of wood chips, which were
used as carrier material. Preliminary results in the
laboratory also indicate that nitrogen removal in grey
water treatment can be enhanced by using inoculants.
Biological waste water treatment based on RBBRs purified
car wash waste waters efficiently, while the reduction of
surfactants was at least 95% and the reduction of
chemical oxygen demand (COD) between 87 and 95% during
the sampling period. Efficient waste water treatment
allows automatic car washes to recycle water used for
washing. The main challenges for the quality of purified
water seems to be optimal nutrient input and an on-line
monitoring system for water quality.
We conclude that waste water treatment technology based
on microbial biofilms is an efficient alternative, at
least in smaller units suitable for single family homes.
Although not tested in VESITURVA, we believe that the
units and the technology can be upscaled and adapted to
at least cover the needs of several families or a small
village. Furthermore, the results regarding removal of
the micropollutants tested were promising, and it is
likely that many other organic micropollutants would
behave similarly in multi-phase biofilm treatment
systems.
AB - Municipal and industrial waste waters in Finland are
treated before their release into the environment. New
legislation also requires that waste waters from all
households with running water are treated before release,
whereas the methods for treatment may vary. In the
Tekes-Symbio project VESITURVA research groups at the
University of Helsinki, VTT, Tampere University of
Technology and Lahti University of Applied Science, in
collaboration with companies in the field and municipal
stakeholders, pooled their resources in an effort to
study and improve waste water treatment.
In the case of household waste waters, minimum removal
requirements exist only for the bulk components, organic
matter (BOD, COD), nitrogen, and phosphorus. While we
also monitored the removal of these components in
VESITURVA, the main focus was on micropollutants
(pollutants that exist in waste water in ng per litre to
µg per litre concentrations, for example hormone
disruptors, farmaceuticals, musks, components of personal
care products etc.) - how they behave and how their
removal can be improved.
In VESITURVA we tested waste water treatment methods that
are based on biofilms colonising the surfaces of matrix
materials using multi-phase water treatment systems,
where the water passes through two or three reactors. The
model substances for the micropollutant removal process
were Bisphenol A (BPA), a component used in the plastics
industry, and the commonly used polycyclic musk compound
HHCB. Two different types of reactors were used for
studying the effect of biofilm activity: Rotating Bed
Bioreactors (RBBR), where the biofilm develops on plastic
beads with a large surface area, and Fixed Bed
Bioreactors (FBBR), where wood chips were used as the
support. In both cases a continuous or semicontinuous
flow of waste water passed through the reactors. In the
RBBR set-up, municipal waste water was led through a
three-phase treatment process, while in the FBBR
artificial grey water was treated in a two-phase process.
In both processes, the removal of the bulk components was
good, and substantial reductions were also achieved in
the case of the model micropollutants. Multi-stage
biofilm reactors seemed to be efficient at removing BPA
and musk HHCB from waste water. Major parts of the
micropollutants were already removed in the first
reactors but the model of sequential reactors enhanced
the removal of both BPA and HHCB. Diversity of bacterial
communities decreased as a function of time suggesting
that the bacterial communities in the reactors became
specialized over time. The same bacterial groups were
dominant in all sequential reactors, but differences were
observed at genus taxonomic level. Also, the microbial
diversity was similar to that seen earlier studies of
waste water treatment microbiology. Carrier material
(polyethylene, wood chips) affected the biofilm community
profile in FBBR.
The performance of FBBR in grey water purification was
evaluated in field conditions when the reactor was
installed in a detached house. The nitrogen removal
efficacy of the reactor was very good and the maximum
nitrogen removal efficiency in the system was 84%.
Nitrogen removal in grey water treatment system was
verified by an evaluation of the abundance of
denitrifying microbes. The performance of the grey water
treatment system was returned to the original level in
1-2 weeks after the replacement of wood chips, which were
used as carrier material. Preliminary results in the
laboratory also indicate that nitrogen removal in grey
water treatment can be enhanced by using inoculants.
Biological waste water treatment based on RBBRs purified
car wash waste waters efficiently, while the reduction of
surfactants was at least 95% and the reduction of
chemical oxygen demand (COD) between 87 and 95% during
the sampling period. Efficient waste water treatment
allows automatic car washes to recycle water used for
washing. The main challenges for the quality of purified
water seems to be optimal nutrient input and an on-line
monitoring system for water quality.
We conclude that waste water treatment technology based
on microbial biofilms is an efficient alternative, at
least in smaller units suitable for single family homes.
Although not tested in VESITURVA, we believe that the
units and the technology can be upscaled and adapted to
at least cover the needs of several families or a small
village. Furthermore, the results regarding removal of
the micropollutants tested were promising, and it is
likely that many other organic micropollutants would
behave similarly in multi-phase biofilm treatment
systems.
KW - waste water treatment
KW - biofilm
KW - carrier
KW - pollutant
KW - microbial diversity
M3 - Report
SN - 978-951-38-7991-4
T3 - VTT Technology
BT - Waste water treatment by multi-stage biofilm processes
PB - VTT Technical Research Centre of Finland
CY - Espoo
ER -