LIFE Project
LIFE03 ENV/P/000521
LAYMANS REPORT
VAPOUR PHASE BIOREACTORS FOR AGRO-NON-FOOD
INDUSTRIES
Place:
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End Date:
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Project Details
Porto, Portugal
01/09/2003
31/08/2005 Extension: 30/11/2005
24 months Extension (months): 3
464.704 €
202.420 €
43,6 %
50,0 %
Beneficiary
Universidade Católica Portuguesa – Escola Superior de
Biotecnologia
Paula Castro
Rua Dr. António Bernardino de Almeida 4200 – 072 Porto,
Portugal
Rua Dr. António Bernardino de Almeida 4200 – 072 Porto,
Portugal
+351 22 558 00 59
+351 22 509 03 51
plc@esb.ucp.pt
www.esb.ucp.pt/SoNatura
PARTNERS
CTCOR - Centro Tecnológico da Cortiça, Rua Amélia Camossa, 4536 – 904, Santa Maria de Lamas, Tel.
+351 22 764 57 97
GRANOTEC, Importação e Exportação de Granulados Técnicos de Cortiça. S. A., Avenida Francisco Sá
Carneiro, 4535 São João Vêr, Tel. +351 256 379 530
CTIC – Centro Tecnológico das Indústrias do Couro, Apartado 158 – São Pedro, 2384-909 Alcanena, Tel.
+351 249 891 316
MARSIPEL – Indústria de Curtumes, S.A., Av. Joaquim Pereira Henriques nº 6, 2384 – 909, Alcanena,
Tel.+351.249.891437
SoNatura Project
1. SoNatura Project Aims and Objectives
SoNatura Project aims at promoting the application of Vapour Phase Bioreactors
(VPBs) for gas emission control on Agro-non-Food Industries (AnFI), namely Granotec
(cork industry) and Marsipel (leather industry), through demonstration actions followed
by dissemination campaigns directed to the target industrial sectors, which are
coordinated by their associated technological centres, namely CTCOR (cork industry)
and CTIC (leather industry). According to several BREF reports (e.g., tanning skins,
http://eippcb.jrc.es), VPBs are classified as Best Available Technologies (BAT) for the
treatment industrial gaseous emissions containing Volatile Organic Carbons (VOCs).
VPBs are natural and cost-effective solutions, in both capital and operational
requirements, using microbial cultures to degrade the VOCs to inert compounds,
through their oxidative biodegradation into water and carbon dioxide.
The following objectives were set for the SoNatura project:
- Develop VPBs for treatment of air emissions from AnFI;
- Demonstrate and validate the application of a Best Available Technology (BAT) in
the target industrial sectors through the use of a prototype VPB;
- Raise awareness in the industrial target sectors to the air pollution problems, aiming
to widen the application of VPBs through the different industrial sectors;
- Develop highly skilled human resources on VPBs;
- Knowledge dissemination: enhance, both at intra and inter-industrial sectors, the
application of VPBs through various dissemination activities such as seminars, best
practice manuals, etc.;
- University–Industry: proceed with university openness towards the industrial world.
The expected results from the SoNatura Project were the following:
- Characterise the main pollutants present in the AnFI gaseous effluents and evaluate
its preliminary biodegradability through literature reviews;
- Enrich microbial cultures able to degrade the target pollutants through the
enrichment studies;
- Gain insight into the application of VPBs on the treatment of the target industrial
gaseous emissions;
- Demonstrate the application of VPBs as BAT on leading industries from major
economical sectors of the selected AnFI;
- In-situ operation of VPB prototypes with optimised conditions;
- Develop public awareness on the application of VPBs as BAT through the
development of active dissemination campaigns;
- Consolidate the openness of the academic world to the industrial sector by
increasing the links of the industrial sector towards the academic world through the
development of feasible solutions able to solve industrial problems.
2. Environmental Impact of the SoNatura Project
2.1. The Environmental Problem
Emissions of Volatile Organic Compounds (VOCs) into the air contribute to the local
and transboundary formation of photochemical oxidants, i.e. ozone, in the boundary
layer of the troposphere, which cause damage to natural resources of vital
environmental and economic importance and, under certain exposure conditions, has
SoNatura Project
harmful effects on human health. This is partly due to the formation of what is
commonly known as "summer smog". High concentrations of ozone, a potent
greenhouse gas, in ground-level air can impair human health – vulnerable members of
the population, such as children and elderly individuals, can experience symptoms such
as sore eyes, sore throats or even serious respiratory problems.
VOC definition:
The EPA (US Environmental Protection Agency) has defined a Volatile Organic
Compound (VOC) as any compound of Carbon that participates in atmospheric
photochemical reactions. The term VOC, usually refers to hydrocarbons, especially
those found in the gaseous state at ambient conditions. VOCs are sparingly soluble in
water with boiling points up to ca. 200ºC and with molecular masses in the range of 16250 g mol-1.
2.2. Main sources of VOC emissions
The main sources of VOCs emissions are:
- mobile sources, exhaustion from vehicles;
- point-sources, mainly derived from the use of organic solvents in several industries
such as chemical plants, paint and varnish, surface coating and printing.
Due to the volatility of the organic solvents, VOCs are emitted either directly or
indirectly into air in many of these processes. A number of organic compounds – such
as carcinogens and mutagens substances - are directly harmful to health. According to
the European Pollutant Emission Register (EPER, 2003) ca. 550 kton/year are emitted
to air, with refineries, basic organic chemicals and the use of organic solvents being the
major contributors. Figure 1 represents the VOCs emissions from the major industrial
sectors (EPER, 2003).
Basic Organic Chemicals: 114.043 kt
Oil and gas refineries: 213.926 kt
-1
Surface treatment (>200 td ): 93.432 kt
Metal industry: 34.802 kt
Pulp industries (>20 td-1): 20.358 kt
Others: 58.978 kt
Figure 1: Emissions of VOCs per industrial activity (source: EPER, 2003).
SoNatura Project
2.3. Legal demands
Due to the long-range transboundary character of air pollution and to the awareness that
the mechanism of photochemical oxidant creation is such that the reduction of
emissions of VOCs is necessary, the Geneva Protocol - concerning the control of
emissions of VOCs or their Transboundary Fluxes - was adopted in 1991. It has entered
into force on 29 September 1997. This Protocol specifies options for emission reduction
targets that have to be chosen upon signature or upon ratification, including 30%
reduction in emissions of VOCs by 1999 using a year between 1984 and 1990 as a
basis. Stringent limits are foreseen.
In Europe, different legal instruments have been adopted to limit VOCs emissions,
namely:
- Directive 94/63/EC aims to prevent emissions of VOCs to the atmosphere during the
storage of petrol at terminals and its subsequent distribution to service stations;
- Directive 1999/13/EC on the limitation of emissions of VOCs due to the use of
organic solvents in certain activities and installations (the so-called VOC Solvents
Directive) is the main instrument for the reduction of VOC emissions in the
European Community. The Directive sets emission limit values (expressed in terms
of the maximum solvent concentration in waste gases) and fugitive emission values
(expressed as a percentage of solvent input). Industrial operators can be exempted
from the above-mentioned limitations, provided that they achieve by other means the
same reduction as would be made by applying them;
- Directive 2004/42/EC on the limitation of emissions of VOCs due to the use of
organic solvents in certain paints and varnishes and vehicle refinishing products (the
so-called VOC Paints Directive) establishes limit values for the maximum VOC
contents of decorative paints and other products covered by the Directive.
Legal obligations and respective deadlines
Existing installations must comply with currently established legal requirements no
later than 31 October 2007 - period consistent with the timetable for compliance of
Council Directive 96/61/EC of 24 September 1996, concerning Integrated Pollution
Prevention and Control (IPPC). The adaptation to the new legal requirements includes
the preparation of an emissions reduction plan and compliance with emission limit
values;
New installations or Existing installations that are subjected to a substantial change
must comply with currently established legal requirements.
2.4. Available Technologies for VOCs Emission Control
According to the currently in place legal requirements, industries can choose the most
cost-effective way to achieve the required reductions: either by substituting high-solvent
products by low-solvent or solvent-free products, or by the use of abatement
technologies.
Figure 2 describes the most applicable treatment technologies (recovery and abatement)
given the characteristics of the VOC emission: flow and concentration.
SoNatura Project
100000
Incinerators:
Flow (Nm3/h)
Thermal, Catalytic and Regenerative
10000
Vapour Phase
Recovery
Regenerative
1000
100
Scrubbing
Bioreactors Adsorption
Non-Regenerative
Adsorption
10
1
Technologies
Recovery
Technologies
10
100
Concentration (g/Nm3)
Figure 2: Available treatment technologies for VOCs emission control.
Classical physical-chemical techniques, including incineration and activated carbon
adsorption, are currently established technologies for VOC emissions control. The
disadvantages of such technologies include high-energy costs, the use of chemicals, and
the production of waste products.
Technology selection criteria:
- Cost-efficient in both capital investment and operational costs;
- Effective solution able to respond to the currently established legal limits;
- Realiable technology, with in-situ historical applications;
- Versatile solution, able to respond to stricter legal limits.
2.5. Vapour Phase Bioreactors: cost-benefit analysis
Vapour Phase Bioreactors (VPBs) offer a natural solution for the treatment of VOCs,
through biodegradation of the compounds into water and carbon dioxide, and are
regarded as Best Available Technologies (BATs) to control industrial gas emissions
according to several BREF reports (e.g., tanning skins, http://eippcb.jrc.es).
In VPBs, the trickle-bed reactor is the state-of-the-art. This technology presents as main
advantages over biofilters, the most commonly used VPB: i) easy elimination of
degradation products, and; ii) easy control of the biological process conditions.
The main limitations when considering the implementation of VPBs in-situ can be
attributed to: i) inability to biodegrade the target pollutants; ii) variability of gaseous
SoNatura Project
emission composition overtime (organic concentration and type of organic compounds),
and; iii) biomass overgrowth.
Bioscrubbers offer the highest VOCs elimination capacities, although its performance is
strongly influenced by mass transfer phenomena.
Treated Gas
▲
◄
◄
▲
Polluted Gas
►
Effluent
Outlet
Mineral
Medium
Figure 3: Schematic representation of a trickle-bed reactor.
VPBs have many potential advantages over classical physico-chemical VOC pollution
control systems, such as wet scrubbers and thermal oxidisers. These advantages include:
• low energy consumption;
• low operation and maintenance requirements;
• excellent reliability when properly designed and operated;
• lower capital investment.
Biological treatment of gaseous emissions contaminated with VOC also offers
advantageous solutions since they are natural treatment systems, almost without waste
generation, being well accepted by the public.
3. Adopted Methodology and Technologies
VPBs are tailored made technological solutions. The work carried out during the project
lifetime involved the initial characterisation of the environmental problem and the
enrichment of microbial cultures able to biodegrade the pollutants identified.
Characterisation of the treatment process mimicking the industrial gaseous emissions
from Granotec and from Marsipel was carried out at laboratorial scale. Upon
characterising both treatment processes at laboratorial scale, the design of pilot-scale
VPB was carried out using a mathematical model. The Beneficiary institution
coordinated and carried out these tasks. The associated industrial partners coordinated
the subsequent operation of the pilot-scale units at the industrial sites. Figure 4 presents
a schematic representation of the SoNatura project structure and activities.
SoNatura Project
Figure 4. Schematic representation of the SoNatura project structure.
Techniques used for the development of the project
- Analytical techniques: gas chromatography for the identification of the
VOCs present in the gaseous emissions and for monitoring the efficiency of
the VPBs (follow-up of the biological treatment);
- Microbiological techniques: enrichment techniques for the isolation of
microbial cultures able to degrade the target pollutants present in the gaseous
emissions;
- Mathematical techniques to develop the mathematical model.
Technologies
- VPB prototype for operation at a laboratory scale: a 1,5 l bioreactor has been
used to treat the target gaseous emissions (Figure 5).
Figure 5.. Schematic representation of the VPB bioreactor used at laboratory scale. Legend: 1pressurised air; 2,3-flow meters; 4- saturation vessel containing target pollutants; 5- saturation
vessel containing water; 6- y shape connecter; 7- gas mixer Schott flask; 8- inlet gas; 9- stirred
bioreactor; 10- outlet gas; 11- minimal salts medium inlet; 12- minimal salts medium outlet.
Upon the successful operation of the VPB at laboratorial scale the design of the
VPB prototype was carried out. Upon construction, the prototype was
implemented and operated in-situ and the treatment performance was
SoNatura Project
characterised. Pictures of the VPB prototypes implementation in-situ are presented
in Figures 6.
6.B
6.A
Figure 6. Photographs of the VPB prototypes implemented in-situ at Marsipel (Fig. 6.A) and at
Granotec (Fig. 6.B).
4. Results from Marsipel & Granotec Case-Studies
The work carried out during the study involved the characterisation of the treatment
process of both Marsipel and Granotec industrial gaseous emissions from laboratorial to
pilot-scale.
Gas emission characterisation
The main VOCs present in the Marsipel gaseous emissions were identified as 1-metoxy2-propanol, 2,6-dimethyl-4-heptanone and 2-butoxyethanol, present in the aqueous
based product, and toluene, butylacetate and 1-methoxy-2-propanol in the solvent-based
product. At Granotec, toluene was identified as the predominant pollutant present in the
gaseous emissions.
Studies at laboratorial scale
The studies carried out at laboratorial scale aimed at:
- Enrichment of microbial cultures able to degrade the main VOCs present in the
gaseous emissions.
- Development of analytical methods able to monitor the VOCs disappearance;
- Development of a laboratory scale VPB for the treatment of the main VOCs derived
from Marsipel and Granotec industries. The treatment performance of this VPB was
optimised.
The laboratorial studies were conducted in a 1.5 litres reactor operated in a continuous
mode, at room temperature and pH 7. The reactor was inoculated with the enriched
microbial cultures and was fed with the target VOCs. Several operating scenarios were
tested and the VPB was operated with an 8 h cycle period and weekend shutdowns.
SoNatura Project
For the Marsipel case-study, the VPB had an overall good performance for the treatment
of the VOCs present in the gaseous emission. Removal efficiencies of or very close to
100% were obtained for the majority of the target pollutants (total inlet concentrations
up to 500 mg m-3). When the VPB was exposed to higher organic loads a decrease in
the removal efficiencies was observed.
A VPB was successfully developed for the treatment of the main VOC emitted at
Granotec, i.e., toluene. The treatment efficiency, when exposed to inlet concentrations
of 85 mg m-3, was ca. 70%. Under the above conditions, toluene concentration in the
gaseous outlet was always in compliance with the legal limits.
Scale-up and VPB Prototype operation in-situ
Upon successful operation of the VPB at laboratorial scale, when exposed to treatment
scenarios mimicking the conditions to be found in-situ, a mathematical model was
developed and used in the scaling-up and design of the VPB prototypes.
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0
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RE (%), OL & EC (g/h/m3
IN, OUT & Legal (mg/Nm3
The Marsipel VPB prototype, with a volume of 2.4 m3 (Figure 6.A), and the Granotec
prototype, with a volume of 5.3 m3 (Figure 6.B), were established and operated in situ,
fed with a vacuum pump at maximum flows of 1500 m3/h. They were both monitored at
their inlet (up to ca. 140 mg/Nm3) and outlet showing average treatment efficiencies
higher than 50%, with the majority of the values found at the outlet of the bioreactors
being under the currently established legal limit (< 50 mg/Nm3), which evidenced the
applicability of this treatment solution (Figures 7 and 8). The prototypes also showed
capacity to deal with variable treatment conditions, which are associated to the
characteristics of the industrial process.
IN
OUT
Legal
RE(%)
OL
EC
0
120
Time (day)
Figure 7. Efficiency of theVPB Prototype operated in-situ at Marsipel.
During the Marsipel VPB operation the following relevant aspects were highlighted:
- at Marsipel, the production process was found to be highly variable due to the typical
batch production of small quantities of leather products, which led to continuous
interruptions for restart and calibration of the industrial machinery. Thus, the Marsipel
VPB was exposed to pronounced dynamic treatment conditions;
SoNatura Project
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- the VPB was operated 5 days a week 8 shifts per day, requiring negligible
maintenance work;
- after a one-month period of interruption (industrial shutdown), the VPB recovered its
treatment performances upon re-inoculatation;
- the VPB was operated under various regimes, being sequentially exposed to higher
organic loads;
- the VPB presented high removal efficiencies with the majority of the concentrations
values found at the outlet of the VPB being below the established legal limit.
IN (mg/m3)
OUT (mg/m3)
Legal (mg/m3)
RE (%)
OL (g h-1m-3)
EC (g h-1m-3)
0
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40
60
80
Time (day)
Figure 8. Efficiency of theVPB Prototype operated in-situ at Granotec.
During the Granotec prototype operation the following relevant aspects were
highlighted:
- at Granotec, the production process was found to be fairly stable;
- the VPB was operated 5 days a week 8 shifts per day. The VPB required negligible
maintenance work. The VPB was exposed to a 15-day starvation period and did not
required re-inoculation to restart the treatment process;
- the Granotec VPB showed high removal efficiencies with the majority of the outlet
values being below the established legal limit.
5. Transferability of the SoNatura Project results
With the successful demonstration of both VPB prototypes implemented in-situ at
Marsipel and Granotec, there is potential to the implementation of VPB units in other
industries belonging to target industrial segments.