Application of Levapor Bio Carrier for the treatment of high Strength Industrial Effluents

1. Biotreatment of Industrial Effluents
by
LEVAPOR BIOFILM TECHNOLOGIES
Various industrial production activities require large quantities of water for
different purposes, e.g. for washing of raw materials and final products, as
medium for reactions, for cooling, etc. During these processes water streams
get in contact with different organic and/or inorganic materials and become
polluted. Unlike municipal sewage, industrial effluents are polluted with
different pollutants with changing quality (composition) and quantity, whereby
many of them are only slowly or non biodegradable and also sometimes toxic
(colours, additives, biocides, etc.).
Fig. 1 Untreated industrial effluents
While
 municipal treatment plants can be designed on basis of number
population and some further indicators, 
 industrial plants do require still serious preliminary work, also practice
oriented research and test work, resulting in tailor-made-solutions, 
 biodegradability of pollutants and establishment of process
parameters represent the main targets. 
Since 1975 we have conducted tests on biodegradation and bioprocess
optimisation, respectively process designs for industrial and municipal
clients, developing new, innovative bio treatment technologies, applied in
several industrial branches, like:

2.  Chemistry, agrochemicals and pharmaceuticals, 
 Fermentation technologies (antibiotics, enzymes, breweries, etc) 
 Petrochemicals and refineries, 
 Pulp and paper, textile and at least 
 Food industry: sugar mills and beverages. 
Biological removal of pollutants depend different factors:
Chemical structure –organic acids, alcohols, aldehydes, amines are easily
degradable, while pollutants containing two or more methyl or nitro groups
show remarkably slower degradability. Structure may decrease solubility,
respective bioavailability of a molecule, hinder microbial attacks, but also
inhibit the degradation process.
Waste water matrix- concentration and quality of all pollutants do influence
composition of biomass of sludge flocs, while increasing salinity lowers
food uptake of biomass.
Microbial strains relevant for degradation of certain pollutants must be
present in the bioreactor.
Milieu conditions - pH, temperature, redox potential, etc. are also essential
for microbial activities.
However, by applying methods of modern biotechnology, even these pollutants
can be degraded biologically both in laboratory and also in practice.
Key factors of their removal are
 Presence of active, specific active biomass in required quantity, 
 Optimal conditions for the efficient and stable degradation processes, 
 Bioreactors , ensuring optimal conditions, respectively 
 Retention and protection of relevant active microbial strains. 
Microbial strains represent mixtures of single strains, able for breaking different
chemical bounds. They show often slow growth rates and weak flocculation,
resulting in their wash-out from bioreactor and in unstable bioprocesses.
Optimal process conditions and parameters can be determined in lab scale
tests, under anaerobic, microaerobic and aerobic conditions.
Immobilisation of biomass
Retention of specialized biomass in bioreactor and their protection from toxic,
inhibitory effects can be achieved by fixation of microbial cells on adsorbing,

3. porous LEVAPOR carrier, generating highly active biofilms resistant to inhibitors
and enabling stable processes (Fig. 2). Positive effects of this method have been
proven by adequate biotests under aerobic and anaerobic conditions.
Fig.2 LEVAPOR-carrier: cross section (left) and colonised by biofilm of
anaerobic bacteria
Due to high adsorbing capacity and porosity of LEVAPOR carrier
 hazardous, inhibiting pollutants become adsorbed on carrier surface,
resulting in remarkably lower inhibitory effects in the liquid phase and 
 faster microbial colonisation and generation of active biofilm takes place,
resulting in 
9
conc.(m M)
8
7 2-CA susp.org.
6 adsorption on
Cl
-
released
5
LEVAP OR
4
3
2
1
2-CA-immobil.
240 hr0 hr.
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Fig. 3 Biodegradation of 1000 mg/L (7,8 mM) of 2-Chloroaniline (2-CA) by
suspended, and on LEVAPOR fixed microorganisms
1
(
1
Prof.Streichsbier, et al., University of Vienna, Austria)

4. - higher resistance of microbial cells in biofilm against toxic effects,
- higher process performance; degradation of adsorbed pollutants and
- biological regeneration of adsorbing capacity of LEVAPOR (fig. 3).
Effects of biomass immobilisation were investigated in batch tests for biodegra-
dation of 1000 mg/L of toxic 2-Chloroaniline (2-CA) under aerobic conditions.
While suspended microorganisms became inhibited by 7.8 mM of 2-CA,addition
of LEVAPOR, followed by adsorption of 2-CA on carrier surface reduced its
concentration (and toxicity) in liquid phase within 2 hours to 3.2 mM, enabling
start up and a quantitative biodegradation within 240 hrs of 2-CA including also
that of the adsorbed fraction, indicated by release of Cl
-
ions.
Nitrification of industrial effluents
is not easy because of quality and salinity fluctuations. Increased salinity
results in decreased uptake of organic pollutants and especially nitrogen,
meaning lower degrees of COD- and N-elimination. Presence of even low
concentrations of special inhibitors results often in a crash of nitrification
process even under continued non inhibited COD-removal.
By immobilizing nitrifying biomass, negative effects of inhibitors can be
reduced remarkably (Fig. 4, right: 94.5 % nitrification, versus only 28% achieved
by suspended biomass, left). Both, higher resistance and higher number of
microbial cells fixed on carrier do contribute to stability of the process.
220
NH4N
207
195200
[mg/L] 28 %
180
inlet
160 149
94,9 %
outlet
140
120
100
80
60
40
20 10
0
suspended biomass immobilisedbiomass
Fig.4 : Effect of biomass immobilisation on nitrification of saline and inhibiting
chemical effluents (salinity:20-25 g/L,COD~1600mg/L) at Lv~ 0,25gN/Lxd.

5. Biodegradation of industrial pollutants under anaerobic conditions
Similar positive effects of LEVAPOR have been confirmed also in biotests under
anaerobic conditions, for degradation of 2-Chlorobenzoic acid (2-CBA), a quite
strong biocide, using methane production as indicator of degradation. While
non-modified-PU-foam or sintered glass carrier showed only small effects with
slow generation of methane, the anaerobic reactor with LEVAPOR within few
days after start up achieved a remarkable biogas production, completed within
18 to 20 days(fig.5).
Fig. 5 Effect of carrier type on biodegradation of 2-Chlorobenzoic acid
under anaerobic conditions
3
(
3
Prof.H.Sahm et al., University of Düsseldorf, Germany)
Biotreatment of toxic pulp mill effluents
Due to the generation of toxic intermediates under aerobic conditions,
biotreatment of several complex organic pollutants with classical activated
sludge achieves only moderate results, while anaerobic treatment performs
remarkably higher removal.
Aerobic treatment of pulp mill bleaching effluents, containing chlorinated toxic
pollutants, resulted only 35 to 40 % COD removal, however anaerobic biofilms
fixed on adsorbing, porous carrier achieved 65 to 70 % removal and due to a
remarkable conversion of pollutants, 45 to 60 % of residual COD could be
eliminated in an aerobic post-treatment step (Fig. 6).

6. Fig. 6 Anaerobic treatment of toxic pulp mill bleaching effluents with biofilms
fixed on different carrier material: 1. LEVAPOR 2. Activated carbon
3. PU-foam and 4. suspended biomass as control
LEVAPOR supported biofilm reactors
Two reactor types are suitable for effluent treatment by LEVAPOR supported
biofilm technology:
 FLUIDISED BED REACTORS or MBBR (moving bed bioreactor) as
main treatment step and 

 BIOFILTERS for POST-TREATMENT. 
Most practicable are fluidised bed reactors, containing 12 to 15 vol. % LEVAPOR .
Due to the low density of the cubes, even oxidation devices of existing plants are
sufficient for the fluidisation of the filter bed, enabling easier upgrading of existing
plants. Retention of carrier with 20x20x7 mm within preferably bottom-aerated
reactors occurs via adequate screens and/or grids.

7. Aerated reactor
Clarifierwith carrier
Fig. 7 Basic flow-sheet of an aerobic fluidised bed reactor
inlet
outlet
air
sludge
Fig. 8 Basic flow sheet of a biofilter
Biofilters – may contain up to 60-70 vol.% LEVAPOR and can be operated in up
flow or down flow mode. They are preferably applied for advanced treatment of
biologically pre treated effluents, containing lower pollutant concentrations and
suspended solids. Due to lower inlet concentrations, they can be operated at
shorter retention times, meaning also lower reactor volumes. Especially after
seeding with proper biomass, bio filters are very suitable for removal of micro-
pollutants.

8. Inlet Outlet LEVAPOR-BIOFILTER
Parameter WWTP Outlet-LVP Elimination
g/l mg/l mg/l %
Chemical site-1
TOC (mg/L) 37 - 60460- 540 40-95 20- 60
Aniline n.a. 40-150 4,0-10,0 90- 93
Bisphenol-A n.a. 10-128 0,0- 9,0 93-100
Nitrobenzene n.a. 25-130 0,5- 24,0 82 - 98
Chemical site-2
COD (mg/L) 3450- 4720 340- 460 190-260 25- 45
Toxicity, GD n.a. 1:100- 500 1:30-250 1:50- 90
Tab. 1 Removal of hazardous pollutants and toxicity by post-treatment of
different effluents in aerobic biofilters using LEVAPOR-carrier
140,0
BPA ( g/L)
120,0
100,0
80,0
60,0
40,0
in
20,0
0,0
ou
days
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29
Fig. 9 Biodegradation of bisphenol-A (BPA) in a LEVAPOR-supported biofilter as
post-treatment step
Case histories
Pulp mill effluents
Pilot tests, carried out after encouraging preliminary results (Fig. 6) confirmed,
that anaerobic-aerobic treatment using biofilm technology represents a highly
efficient and practicable treatment method for these toxic effluents, whereas
thanks to biofilms volume of anaerobic reactors could be reduced by 75 %,
enabling savings of more than 10 million € ( Euros ). The plant is in operation
since 1990 (Fig.10). In order to confirm contribution of biofilm technique, during
the start up phase only two of three methane-reactors were filled with carrier.