1113
© IWA Publishing 2015 Water Science & Technology
|
71.8
|
2015
Wineries wastewater treatment by constructed wetlands: a review F. Masi, J. Rochereau, S. Troesch, I. Ruiz and M. Soto
ABSTRACT The application of wetland systems for the treatment of wineries wastewater started in the early 1990s in the USA followed a few years later by France, Italy, Germany and Spain. Various studies demonstrated the efficiency of constructed wetlands (CWs) as a low cost, low maintenance and energy-saving technology for the treatment of wineries wastewater. Several of these experiences have also shown lessons to be learnt, such as some limits in the tolerance of the horizontal subsurface flow and vertical subsurface flow classic CWs to the strength of the wineries wastewater, especially in the first stage for the multistage systems. This paper is presenting an overview of all the reported experiences at worldwide level during the last 15 years, giving particular attention and provision of details to those systems that have proven to get reliable and constant performances in the long-term period and that have been designed and realized as optimized solutions for the application of CW technology to this particular kind of wastewater. The organic loading rates (OLRs) applied to the examined 13 CW systems ranged from about 30 up to about 5,000 gCOD/m2 d (COD: chemical oxygen demand), with the 80th percentile of the reported values being below 297 gCOD/m2 d and the median at 164 gCOD/m2 d; the highest OLR values have in all cases been measured during the peak season (vintage) and often have been linked to lower surface removal rates (SRRs) in comparison to the other periods of the year. With such OLRs the SRRs have ranged from a minimum of 15 up to 4,700 gCOD/m2 d, with the 80th percentile of the reported values being below 308 gCOD/m2 d and the median at 112 gCOD/m2 d. Key words
F. Masi (corresponding author) Iridra, Via La Marmora 51, 50121, Florence, Italy E-mail: [email protected] J. Rochereau Agroenvironnement – Syntea, Lieu-dit Belle-Croix, 33 490 Le-Pian-sur-Garonne, France S. Troesch Epurnature, 12 Rue Toussaint Flechaire, F-84510, Caumont sur Durance, France I. Ruiz M. Soto Department of Physical Chemistry and Chemical Engineering I, University of A Coruna, Rúa da Fraga n◦10, 15008 A Coruna, Galicia, Spain
| constructed wetlands, high organic load, hybrid systems, multistage treatment wetlands, treatment wetlands, wineries wastewater
INTRODUCTION World wine production is estimated nowadays to be around 250 millions of hectolitres per year, with about 62% of this total amount created in Europe, and is generating relevant fluxes of wastewater produced during the grape processing (vintage and racking) period and the following months when bottling and cleaning of containers are almost continuous operations. These fluxes of winery wastewater are often a concerning environmental problem in wine-producing countries (Serrano et al. ). This particularly complex wastewater is characterized by fluctuations in terms of quality and quantity during the whole year, which are caused by different factors such as the adopted industrial process chain and its seasonality and the kind of produced wine; on average for 1 L of wine about 1.6–2.0 L of wastewater are generated and the ratio between the organic load and the produced wine is 5–10 kgCOD/m3 (COD: chemical doi: 10.2166/wst.2015.061
oxygen demand) (Fernández et al. ; Anastasiou et al. ). Table 1 shows the characterization for wineries wastewater based on the available literature to date. The organic content of winery wastewater consists of highly soluble sugars, 25 different alcohols, acids and recalcitrant high molecular weight compounds (e.g. polyphenols), 26 tannins, and lignins. Detailed studies of the composition of winery wastewater have revealed that ethanol and, to a smaller extent and on a temporary basis, sugars (fructose and glucose) represent more than 90% of the organic load. Organic acids, alcohols, and phenols have variable degradation rates. Biodegradable contaminants (e.g. sugars and alcohols) tend to degrade first, leaving behind wastewater containing less easily degraded compounds, i.e. phenols and tannins (Arienzo et al. ). The phenolic composition of wines depends on the variety of grapes and on the vinification
1114
Table 1
F. Masi et al.
|
|
Wineries wastewater treatment by constructed wetlands: a review
Winery wastewater characteristics in the literature (adapted from Shepherd et al. (2001) and Conradie et al. (2014)) Common
Parameter
Min
Max
Mean
treatment targets
COD mg/L
340
49,103
14,570
120–160
BOD5 mg/L
181
22,418
7,071
20–40
TSS mg/L
190
18,000
1,695
35–80
3.5
7.9
4.9
6–8
2.88
364
26
15–35
pH N mg/L
(NHþ 4 þ
NO 3)
Water Science & Technology
• • •
COD: chemical oxygen demand; BOD5: 5-day biochemical oxygen demand; TSS: total sus-
1. aerobic/anoxic processes using suspended biomass: activated sludge, membrane bioreactors, sequencing batch reactors (SBRs); 2. aerobic biofilm systems: rotating biological contactors, fixed bed biofilm reactors, moving bed biofilm reactors; 3. anaerobic processes using suspended biomass: anaerobic digesters (ADs), anaerobic SBRs; 4. anaerobic biofilm systems using granules (upflow anaerobic sludge blanket (UASB)) or fixed supports (anaerobic filters) or mobile supports (fluidized bed reactors); 5. CWs. Other treatment methods can be chemical oxidation (by Fenton reaction), photocatalysis and fertirrigation (Agustina et al. ).
71.8
|
2015
The main problems in processing this particular wastewater can be listed as:
pended solids.
conditions. Phenolic compounds, which are plant secondary metabolites and the main antioxidant compounds in grapes and grape products, can be divided into two groups: phenolic acids and related compounds and flavonoids. The major phenolic compounds in grape wastes are anthocyanins, catechins, glycosides of flavonols and phenolic acids (Lafka et al. ). Past experiences showed that the winery wastewaters, at certain concentrations, can have phytotoxicity effects on various wetland plants species. Understanding the phytotoxicity of winery wastewater is fundamental to the design and implementation of constructed wetlands (CWs) for its treatment. The ideal plant should tolerate high-organic loads and be capable of removing significant amounts of contaminants and purifying the effluent in a relatively short time period (Arienzo et al. ). Several treatment approaches have been adopted for the wineries wastewater treatment. Often it is stored and partially treated in aerated or facultative ponds and disposed of via post-harvest vineyard irrigation (Storm ). An exhaustive and comprehensive overview of the treatment methods has been produced by Andreottola et al. (); the biological treatments are subdivided into five main categories:
|
• • •
variable pH, usually ranging from 4 to 8 in the different periods of the year (Shepherd et al. ); low nutrient content and consequent unfavorable C/N ratio for the microbial growth; high content of biodegradable compounds that often leads to difficulties in operating biological systems, for instance poor sludge settleability, floc disintegration and increased presence of solids in the treated effluent (Silva et al. ); seasonality and load fluctuations; clogging in filtering reactors; phytotoxicity and microbial inhibition by toxic organic and inorganic compounds, i.e. sulfur, phenols, tannins (Arienzo et al. ).
The application of wetland systems for the treatment of wineries wastewater started in the early 1990s in the USA followed a few years later by France, Italy, Germany and Spain. Various studies (Shepherd et al. ; Masi et al. ; Müller et al. ; Rochard et al. ; Grismer et al. ; Mulidzi ; Vymazal ; Serrano et al. ; de la Varga et al. a, b) demonstrated the efficiency of CWs as a low cost, low maintenance and energy-saving technology for the treatment of wineries wastewater. Several of these experiences have also shown lessons to be learnt, such as some limits in the tolerance of the horizontal flow (HF) and vertical flow (VF) classic CWs to the strength of the wineries wastewater, especially in the first stage for the multistage systems or in the single stage ones. In general terms the treatment train can be related to the size of the winery, which is usually expressed in terms of quantity of produced wine per year (hL/year) and the specific treatment targets and final fate of the effluents. The lower the amount of wastewater to be treated, the simpler usually is the chosen scheme. Nowadays, there are for instance about 100 CW systems operating in Northern and Central Italy for wineries wastewater, and very often, when the productivity is lower than 2,000 hL of wine per year, the treatment scheme consists of a pretreatment by septic or Imhoff tanks, with also an equalization role, followed by a single-stage CW, horizontal subsurface flow beds in most cases or also vertical subsurface flow beds. For bigger size wineries instead the more adopted solutions are combinations of wetland systems (called multistage treatment wetlands) or combinations of CWs with other technologies, like anaerobic digestion systems (UASB,
1115
F. Masi et al.
|
Wineries wastewater treatment by constructed wetlands: a review
hydrolytic upflow sludge blanket (HUSB)) or aerobic biological treatments (SBR, AS).
SUMMARY OF RESULTS FROM DIFFERENT EXPERIENCES For a synoptic view, all the different schemes adopted until now for the treatment by CW systems of wineries wastewater are summarized in Figure 1. To enable comparison, the main characteristics and average results of the systems shown in Figure 1 and described and discussed in the paper are displayed in Table 2. The description and critical review of all the analyzed treatment plants is structured in the following paragraphs by the typology of CWs used in the treatment scheme, followed by more detailed analysis of long-term performances for multistage and combined systems, and general discussion and conclusions. HF CWs Shepherd et al. () described a pilot work for the wastewater treatment in the medium-size winery Fetzer Vineyards, Hopland, California, producing about 182,000 hL of wine per year. The system was a simple HF CW with a surface area of 14.9 m2 (length/width ¼ 2.5) filled with pea gravel (D60/D10 ¼ 2.2; hydraulic conductivity 2 mm/s), receiving the effluent from an upflow coarse-sand filter (0.378 m3 by 0.25 m of height) used as pretreatment, and treating it in a single stage with a long hydraulic retention time (HRT) of about 10 days. The CW was planted with Typha dominicus, Scirpus acutus and some Sagittaria latifolia in October of 1995. In this experience the wastewater has been diluted with increasing final COD concentrations for performing four experiments. The diluted wastewater was applied at the beginning to the CW system at 500 L/d and 993 mgCOD/L (organic loading rate (OLR): 34.5 gCOD/m2 d); then the COD concentration was increased up to 5,000 mg/L (OLR: 164 gCOD/m2 d). With the exception of some reduced plant growth at the front end of the CW, the system did not exhibit any negative responses to high OLRs. Furthermore, the CW system appeared capable of withstanding fluctuating water quality without sacrificing good performances, obtaining on average 98 and 97% COD and total suspended solids (TSS) removal efficiencies. The same paper provides interesting results of a monitoring campaign for the characterization of the wastewater produced by the winery throughout the
Water Science & Technology
|
71.8
|
2015
year. The measured quantity of produced wastewater was about 106–172 m3/d during the peak season and 46– 100 m3/d for the rest of the year; the ratio between wastewater and produced wine was 2.2 L/L. The pH varied between 4 and 8. The COD fluctuations were quite considerable, from 500 to 45,000 mg/L in peak season and from 600 to 13,000 mg/L in off season. Grismer et al. () published a study performed on the same pilot plants where the planted bed, in operation for 3 years, was compared with an unplanted reactor measuring the residence time distribution (RTD) of tracers. The study demonstrated that while tank outflow tracer RTDs could not be described using either plug-flow reactor or simple continuously mixed-system models, 20–35 tanks-in-series models adequately replicated the measured outflow RTDs. No preferential flows were observed in the CW tanks because outflow RTDs were nearly symmetric and very similar. A single stage CW is operating in Italy, at La Croce winery (
© IWA Publishing 2015 Water Science & Technology
|
71.8
|
2015
Wineries wastewater treatment by constructed wetlands: a review F. Masi, J. Rochereau, S. Troesch, I. Ruiz and M. Soto
ABSTRACT The application of wetland systems for the treatment of wineries wastewater started in the early 1990s in the USA followed a few years later by France, Italy, Germany and Spain. Various studies demonstrated the efficiency of constructed wetlands (CWs) as a low cost, low maintenance and energy-saving technology for the treatment of wineries wastewater. Several of these experiences have also shown lessons to be learnt, such as some limits in the tolerance of the horizontal subsurface flow and vertical subsurface flow classic CWs to the strength of the wineries wastewater, especially in the first stage for the multistage systems. This paper is presenting an overview of all the reported experiences at worldwide level during the last 15 years, giving particular attention and provision of details to those systems that have proven to get reliable and constant performances in the long-term period and that have been designed and realized as optimized solutions for the application of CW technology to this particular kind of wastewater. The organic loading rates (OLRs) applied to the examined 13 CW systems ranged from about 30 up to about 5,000 gCOD/m2 d (COD: chemical oxygen demand), with the 80th percentile of the reported values being below 297 gCOD/m2 d and the median at 164 gCOD/m2 d; the highest OLR values have in all cases been measured during the peak season (vintage) and often have been linked to lower surface removal rates (SRRs) in comparison to the other periods of the year. With such OLRs the SRRs have ranged from a minimum of 15 up to 4,700 gCOD/m2 d, with the 80th percentile of the reported values being below 308 gCOD/m2 d and the median at 112 gCOD/m2 d. Key words
F. Masi (corresponding author) Iridra, Via La Marmora 51, 50121, Florence, Italy E-mail: [email protected] J. Rochereau Agroenvironnement – Syntea, Lieu-dit Belle-Croix, 33 490 Le-Pian-sur-Garonne, France S. Troesch Epurnature, 12 Rue Toussaint Flechaire, F-84510, Caumont sur Durance, France I. Ruiz M. Soto Department of Physical Chemistry and Chemical Engineering I, University of A Coruna, Rúa da Fraga n◦10, 15008 A Coruna, Galicia, Spain
| constructed wetlands, high organic load, hybrid systems, multistage treatment wetlands, treatment wetlands, wineries wastewater
INTRODUCTION World wine production is estimated nowadays to be around 250 millions of hectolitres per year, with about 62% of this total amount created in Europe, and is generating relevant fluxes of wastewater produced during the grape processing (vintage and racking) period and the following months when bottling and cleaning of containers are almost continuous operations. These fluxes of winery wastewater are often a concerning environmental problem in wine-producing countries (Serrano et al. ). This particularly complex wastewater is characterized by fluctuations in terms of quality and quantity during the whole year, which are caused by different factors such as the adopted industrial process chain and its seasonality and the kind of produced wine; on average for 1 L of wine about 1.6–2.0 L of wastewater are generated and the ratio between the organic load and the produced wine is 5–10 kgCOD/m3 (COD: chemical doi: 10.2166/wst.2015.061
oxygen demand) (Fernández et al. ; Anastasiou et al. ). Table 1 shows the characterization for wineries wastewater based on the available literature to date. The organic content of winery wastewater consists of highly soluble sugars, 25 different alcohols, acids and recalcitrant high molecular weight compounds (e.g. polyphenols), 26 tannins, and lignins. Detailed studies of the composition of winery wastewater have revealed that ethanol and, to a smaller extent and on a temporary basis, sugars (fructose and glucose) represent more than 90% of the organic load. Organic acids, alcohols, and phenols have variable degradation rates. Biodegradable contaminants (e.g. sugars and alcohols) tend to degrade first, leaving behind wastewater containing less easily degraded compounds, i.e. phenols and tannins (Arienzo et al. ). The phenolic composition of wines depends on the variety of grapes and on the vinification
1114
Table 1
F. Masi et al.
|
|
Wineries wastewater treatment by constructed wetlands: a review
Winery wastewater characteristics in the literature (adapted from Shepherd et al. (2001) and Conradie et al. (2014)) Common
Parameter
Min
Max
Mean
treatment targets
COD mg/L
340
49,103
14,570
120–160
BOD5 mg/L
181
22,418
7,071
20–40
TSS mg/L
190
18,000
1,695
35–80
3.5
7.9
4.9
6–8
2.88
364
26
15–35
pH N mg/L
(NHþ 4 þ
NO 3)
Water Science & Technology
• • •
COD: chemical oxygen demand; BOD5: 5-day biochemical oxygen demand; TSS: total sus-
1. aerobic/anoxic processes using suspended biomass: activated sludge, membrane bioreactors, sequencing batch reactors (SBRs); 2. aerobic biofilm systems: rotating biological contactors, fixed bed biofilm reactors, moving bed biofilm reactors; 3. anaerobic processes using suspended biomass: anaerobic digesters (ADs), anaerobic SBRs; 4. anaerobic biofilm systems using granules (upflow anaerobic sludge blanket (UASB)) or fixed supports (anaerobic filters) or mobile supports (fluidized bed reactors); 5. CWs. Other treatment methods can be chemical oxidation (by Fenton reaction), photocatalysis and fertirrigation (Agustina et al. ).
71.8
|
2015
The main problems in processing this particular wastewater can be listed as:
pended solids.
conditions. Phenolic compounds, which are plant secondary metabolites and the main antioxidant compounds in grapes and grape products, can be divided into two groups: phenolic acids and related compounds and flavonoids. The major phenolic compounds in grape wastes are anthocyanins, catechins, glycosides of flavonols and phenolic acids (Lafka et al. ). Past experiences showed that the winery wastewaters, at certain concentrations, can have phytotoxicity effects on various wetland plants species. Understanding the phytotoxicity of winery wastewater is fundamental to the design and implementation of constructed wetlands (CWs) for its treatment. The ideal plant should tolerate high-organic loads and be capable of removing significant amounts of contaminants and purifying the effluent in a relatively short time period (Arienzo et al. ). Several treatment approaches have been adopted for the wineries wastewater treatment. Often it is stored and partially treated in aerated or facultative ponds and disposed of via post-harvest vineyard irrigation (Storm ). An exhaustive and comprehensive overview of the treatment methods has been produced by Andreottola et al. (); the biological treatments are subdivided into five main categories:
|
• • •
variable pH, usually ranging from 4 to 8 in the different periods of the year (Shepherd et al. ); low nutrient content and consequent unfavorable C/N ratio for the microbial growth; high content of biodegradable compounds that often leads to difficulties in operating biological systems, for instance poor sludge settleability, floc disintegration and increased presence of solids in the treated effluent (Silva et al. ); seasonality and load fluctuations; clogging in filtering reactors; phytotoxicity and microbial inhibition by toxic organic and inorganic compounds, i.e. sulfur, phenols, tannins (Arienzo et al. ).
The application of wetland systems for the treatment of wineries wastewater started in the early 1990s in the USA followed a few years later by France, Italy, Germany and Spain. Various studies (Shepherd et al. ; Masi et al. ; Müller et al. ; Rochard et al. ; Grismer et al. ; Mulidzi ; Vymazal ; Serrano et al. ; de la Varga et al. a, b) demonstrated the efficiency of CWs as a low cost, low maintenance and energy-saving technology for the treatment of wineries wastewater. Several of these experiences have also shown lessons to be learnt, such as some limits in the tolerance of the horizontal flow (HF) and vertical flow (VF) classic CWs to the strength of the wineries wastewater, especially in the first stage for the multistage systems or in the single stage ones. In general terms the treatment train can be related to the size of the winery, which is usually expressed in terms of quantity of produced wine per year (hL/year) and the specific treatment targets and final fate of the effluents. The lower the amount of wastewater to be treated, the simpler usually is the chosen scheme. Nowadays, there are for instance about 100 CW systems operating in Northern and Central Italy for wineries wastewater, and very often, when the productivity is lower than 2,000 hL of wine per year, the treatment scheme consists of a pretreatment by septic or Imhoff tanks, with also an equalization role, followed by a single-stage CW, horizontal subsurface flow beds in most cases or also vertical subsurface flow beds. For bigger size wineries instead the more adopted solutions are combinations of wetland systems (called multistage treatment wetlands) or combinations of CWs with other technologies, like anaerobic digestion systems (UASB,
1115
F. Masi et al.
|
Wineries wastewater treatment by constructed wetlands: a review
hydrolytic upflow sludge blanket (HUSB)) or aerobic biological treatments (SBR, AS).
SUMMARY OF RESULTS FROM DIFFERENT EXPERIENCES For a synoptic view, all the different schemes adopted until now for the treatment by CW systems of wineries wastewater are summarized in Figure 1. To enable comparison, the main characteristics and average results of the systems shown in Figure 1 and described and discussed in the paper are displayed in Table 2. The description and critical review of all the analyzed treatment plants is structured in the following paragraphs by the typology of CWs used in the treatment scheme, followed by more detailed analysis of long-term performances for multistage and combined systems, and general discussion and conclusions. HF CWs Shepherd et al. () described a pilot work for the wastewater treatment in the medium-size winery Fetzer Vineyards, Hopland, California, producing about 182,000 hL of wine per year. The system was a simple HF CW with a surface area of 14.9 m2 (length/width ¼ 2.5) filled with pea gravel (D60/D10 ¼ 2.2; hydraulic conductivity 2 mm/s), receiving the effluent from an upflow coarse-sand filter (0.378 m3 by 0.25 m of height) used as pretreatment, and treating it in a single stage with a long hydraulic retention time (HRT) of about 10 days. The CW was planted with Typha dominicus, Scirpus acutus and some Sagittaria latifolia in October of 1995. In this experience the wastewater has been diluted with increasing final COD concentrations for performing four experiments. The diluted wastewater was applied at the beginning to the CW system at 500 L/d and 993 mgCOD/L (organic loading rate (OLR): 34.5 gCOD/m2 d); then the COD concentration was increased up to 5,000 mg/L (OLR: 164 gCOD/m2 d). With the exception of some reduced plant growth at the front end of the CW, the system did not exhibit any negative responses to high OLRs. Furthermore, the CW system appeared capable of withstanding fluctuating water quality without sacrificing good performances, obtaining on average 98 and 97% COD and total suspended solids (TSS) removal efficiencies. The same paper provides interesting results of a monitoring campaign for the characterization of the wastewater produced by the winery throughout the
Water Science & Technology
|
71.8
|
2015
year. The measured quantity of produced wastewater was about 106–172 m3/d during the peak season and 46– 100 m3/d for the rest of the year; the ratio between wastewater and produced wine was 2.2 L/L. The pH varied between 4 and 8. The COD fluctuations were quite considerable, from 500 to 45,000 mg/L in peak season and from 600 to 13,000 mg/L in off season. Grismer et al. () published a study performed on the same pilot plants where the planted bed, in operation for 3 years, was compared with an unplanted reactor measuring the residence time distribution (RTD) of tracers. The study demonstrated that while tank outflow tracer RTDs could not be described using either plug-flow reactor or simple continuously mixed-system models, 20–35 tanks-in-series models adequately replicated the measured outflow RTDs. No preferential flows were observed in the CW tanks because outflow RTDs were nearly symmetric and very similar. A single stage CW is operating in Italy, at La Croce winery (
