Wine Effluent Treatment

Wine effluent treatment

The production of quality wines requires compliance with hygiene procedures that involve the use of large quantities of water. The wastewater produced is a source of organic pollution, particularly during the harvest.

This effluent results from the various washing operations generated by the wine-making activity: washing the equipment from harvesting to bottling, washing the cellar floors and descaling water or juice.
They comprise an insoluble and a soluble part. It is these elements in solution that pose a problem, as they are rapidly degraded by micro-organisms when effluents are discharged into the aquatic environment. This degradation is accompanied by a high consumption of oxygen, which can cause asphyxiation of the environment and lead to the destruction of fish fauna.

It is for this reason that the direct discharge of untreated wine effluent into the natural environment is strictly prohibited. Regulations require all wineries, whatever their production volume, to have a solution for treating their cellar effluent.

Wine effluent treatment plant

Characterisation of wine-making effluent

What impact do wine-making effluents have on the aquatic environment?

Winegrowing effluents, discharged directly into the natural environment, have a significant and lasting impact on the environment. It is discharged in large quantities over a short period of time (50-60% of effluent volumes are produced during the grape harvest and the first rackings). Their discharge is localised and occurs when rivers are at their lowest. There is no dilution effect.

Finally, due to their high concentration of easily biodegradable organic matter, they are degraded by the micro-organisms present in the aquatic environment, with a high consumption of dissolved oxygen.

Impact des effluents sur le milieu aquatique

Impact des effluents sur le milieu aquatique

Impact of effluent on the aquatic environment

How can the pollutant load of wine effluent be measured?

Installing a wine effluent treatment system requires a good understanding of the volume and concentration of pollutants in the effluent. Installing one or more meters will enable you to accurately measure the water consumed by the wine-making activity. For wineries producing more than 500 hectolitres of wine per year, it is a legal requirement to take regular readings of water consumption linked to the wine-making process. It's very easy to install sub-meters at water points in the winery and outside, if wine-making equipment is washed, not forgetting that of the grape harvesting machine and skips.

The frequency of measurements varies according to the treatment method chosen: monthly for extensive systems such as land application, or daily during periods of high activity (harvest and first rackings) for intensive systems such as activated sludge treatment, or for collective treatment or service provision. The rate of pollution will be assessed by taking representative samples.

pH	4.1 à 6.5
TSS	0.15 to 1.5 g/L
COD	8 to 35 g/L
BOD5	4 to 21 g/L
MA	0.04 to 0.2 g/L
MP	0.01 to 0.06 g/L

Volume of water consumed	150 litres per day
TSS	90 g 0.6 g/L
COD	120 g 0.8 g/L
BOD5	60 g 0.4 g/L
MA	15 g 0.1 g/L
MP	4 g 0.027 g/L

Pollution from wine-growing effluent is often converted to domestic pollution expressed in terms of population equivalents. The parameter used for this conversion is COD or BOD5.

How can you find the right solution for your business?

It is often difficult for winegrowers to choose between the various solutions for treating wine effluent.
The choice should not be based solely on the initial cost, but should also take into account other parameters such as the geographical location of the winery (presence of housing close to the winery), the presence of a collective treatment system, the proximity of the municipal sewage network, the space available for installing an individual treatment system, aesthetic constraints, the availability of non-vineyard land and operating costs.
Schéma des solutions envisageables

Diagram of possible solutions

Physical processes for treating wine effluent

These treatment methods reduce the volume of effluent to obtain a concentrate that can be recycled. In regions where natural evaporation is high (wind and/or low rainfall), concentration can be achieved by natural evaporation in shallow basins or by spraying onto honeycomb panels, and in other regions on panels combined with mechanical ventilation (forced evaporation). Concentration can also be achieved by heating the effluent in evaporators at atmospheric pressure or under vacuum (evapoconcentrator). Concentration by membrane separation does not retain all the soluble organic matter and must therefore be combined with additional treatment.

Treatment of wine effluent by natural and forced evaporation

Principle
Evaporation processes consist of concentrating previously screened effluent under the action of heat and, above all, wind. The effluent can evaporate naturally in sealed basins (natural evaporation) or in an optimised way by projection onto honeycomb panels (forced evaporation). These processes are used in regions with a high water deficit. In areas with less water deficit, evaporation is accelerated by mechanical ventilation. The volume of the effluent storage tank depends on the performance of the evaporation module.
Schema de traitement des effluents par evaporation

Schema de traitement des effluents par evaporation

Diagram of effluent treatment by evaporation

How it is used
The evaporation system consists of a fine screen to prevent clogging, a buffer tank and the evaporation module.

Station de traitement des effluents par evaporation

Evaporation effluent treatment plant

Panneaux dégrilleurs de station d'evaporation

Screening panels for evaporation station

Treatment of wine effluent by fractional condensation evapoconcentration

Principle
After alcoholic fermentation of sugars into ethanol, the effluent is boiled to extract the ethanol and then the water.

How is it used?
For a long time, this technique was not applied to pollution control because of its cost. Today, improvements have made it possible to use this technique to treat wine effluents. The condensate can be recycled in distilleries or in agriculture. The energy required for evaporation is significant. Various systems have been developed to reduce this consumption.

Biological processes for treating wine effluent

Biological processes are widely used to treat wine effluent. The organic matter is degraded by micro-organisms, mainly bacteria, which use the degradation products to grow (increasing the biomass). There are various treatment techniques, the most rustic being spreading on cultivated soil. Other techniques require the construction of treatment plants, which are distinguished by their operating mode, either aerobic (with oxygen supply) or anaerobic (methanisation without oxygen supply).
Aerobic treatment methods differ according to whether the treatment is continuous and intensive (activated sludge), semi-continuous (sequential aeration) or discontinuous (aerated storage).
Wine effluents can also be part of a composting process for vine shoots and plant waste on the farm. It provides organic matter and is used mainly to moisten the compost.

Treatment of wine effluent by spreading

Principle
Spreading wine effluent uses the purifying properties of the soil-plant system. The effluent is spread on cultivated soil during a period that favours the activity of micro-organisms. The soil retains the larger particles and the micro-organisms it contains break down the organic matter contained in the effluent. The plants export the fertilising elements provided by the effluent or resulting from the degradation of the organic matter.

How is it used?

Wine effluent can be spread using a slurry tanker or a sprinkler system.
Spreading by sprinkling concerns farms with land in the immediate vicinity of the production site. Spreading can be carried out by means of a regularly moved gun or a network of fixed sprinklers.
Spreading by slurry tanker means that land far from the production site can be used. This method of spreading is less costly in terms of investment, but requires more manpower.

Spreading must be carried out on regularly cultivated farmland (meadows, cereal crops, etc.), avoiding any run-off, stagnation or deep percolation. Dosages must be adapted to the soil and climatic conditions, and spread evenly over well-drained soil.
It is prohibited during periods of frost, heavy rain, flooding and on steeply sloping land.

Spreading by slurry tanker

Activated sludge treatment of wine effluent

Principle
Treatment of wine-making effluent using activated sludge is an intensive, continuous process carried out in compact tanks with a high oxygen supply. The effluent residence time is a few days. The effluent is degraded by a large biomass consisting mainly of bacteria. The ratio of organic matter to mass of micro-organisms (mass load) is used to size the treatment tanks.
Procédé traitement des effluents vinicoles par boues activées

Procédé traitement des effluents vinicoles par boues activées

Activated sludge process for treating wine-making effluent

How it is used

This technique requires fine sieving (1 mm) and the correction of parameters limiting the development of micro-organisms (neutralisation of effluent and addition of nutrients). The sludge is separated from the treated wine effluent in a decanter and returned to the head of the plant in order to maintain the micro-organism population at a high level.

Bassin d'aération traitement boues activées

Aeration tank for activated sludge treatment

Treatment of wine effluent by sequential aeration

Principle

The SBR (Sequencing Batch Reactor) process is a batch activated sludge process. It is based on running a reactor in sequential mode. It comprises a series of cycles carried out in the same tank and programmed by a clock.

Traitement des effluents vinicoles par aération séquentielle

Treatment of wine effluent by sequential aeration

How it works
The first stage consists of introducing a given volume of wine effluent from a buffer storage tank into the aeration tank. The effluent is then aerated for a period corresponding to the time required for the organic matter to degrade. The third stage is decantation. Finally, a volume of supernatant equal to the volume initially introduced is pumped out and discharged into the natural environment. Following this discharge, a new cycle is started.
Procédé traitement des effluents vinicoles par aération séquentielle

Procédé traitement des effluents vinicoles par aération séquentielle

Treatment of wine-making effluent by sequential aeration

Treatment of wine-making effluent by aerated storage

Principle
Aerated storage is a discontinuous aerobic treatment method. The wine-making effluent is degraded by micro-organisms whose development is encouraged by a supply of oxygen. This technique comprises three phases (aeration, decantation and emptying) which take place in the same structure.

Procédé de traitement des effluents vinicoles par stockage aéré

Wine effluent treatment processes using aerated storage

Implementation
The wine-making effluent is sent to a large-capacity tank equipped with an aeration system. The first stage involves aeration and mixing for a period of two to eight weeks. At the end of this stage, the treated effluent is decanted to separate it from the sludge. In the third phase, the treated effluent is discharged into the natural environment after being checked for compliance with discharge standards. The sludge is removed every four or five years.

Open tank

Sand filter

Inside the tank

Hydroejector

Pumping of treated effluent

Aeration tank

Reed bed

Treatment of wine effluent by composting

Principle
The technique for treating wine-making effluent by composting is based on aerobic biological degradation of the organic matter, through regular humification and turning, which is stored on a covered platform specifically for this purpose.

How is it used?
This method of eliminating effluent, developed by the Gironde Chamber of Agriculture and Souslikoff, involves composting crushed vine shoots, to which can be added any other organic waste from the farm (stalks, pomace, grass clippings, etc.). Wine effluent is used to water the vine shoots, which are very dry.

Dispositif de traitement par compostage - Vignalex

Composting treatment plant - Vignalex

Treatment of wine-growing effluent by reed beds

Principle

The presence of plants indirectly induces a number of mechanisms that promote purification: maintenance of the structure of the bed, supply of oxygen to the filtering medium and development of bacterial flora. At the same time, the presence of plants prevents the organic matter retained on the surface from forming an impermeable crust that would hinder water infiltration.
By oscillating in the wind, the stems maintain a free ring at their base, which facilitates hydraulic circulation in the bed and reduces clogging.

Reed beds

Aquatic plants, and reeds in particular, have a special tissue that enables oxygen to be transferred from the aerial parts (stems and leaves) to the underground parts: it is released by the young roots into the aqueous film surrounding the "root hair". The purifying bacteria present near these roots are thus better supplied with oxygen. For horizontal filters, which are permanently immersed, the oxygen supply by this means is much lower than that provided by the tarpaulin system.

Implementation
The purification capacity of planted filter beds can be exploited in two ways:

Either by infiltrating the water vertically into soils planted with macrophytes and generally drained (vertical flow filter or vertical filter).

The vertical flow bed is an artificial soil made up of several superimposed layers of granular material in which the rhizomes develop. To promote oxygenation of the filter, the water to be treated is injected sequentially into a spreading network placed on the surface of the bed. As the supply network is loaded with water with each batch, the effluent is distributed evenly, avoiding the formation of saturation zones.
The effluent percolates by gravity to drains at the bottom of the basin and is thus evacuated at the bottom of the system.
The relatively short residence time and the fact that the effluent is fed in batches prevent saturation, aerate the mass and encourage aerobic degradation.

Or by circulation of the water in the rhizosphere of the macrophytes via a horizontal path beneath the surface of the soil (horizontal flow filter or horizontal filter).

The horizontal flow bed is an artificial soil whose granulometries are graded into filtering barriers along a horizontal vector. The water to be treated, injected at one end of the filter bed, penetrates horizontally into the structure and is then evacuated by drainage at the other end.
The water is generally fed continuously, so as to saturate the materials permanently and encourage anaerobic degradation.
The only aeration possible is slight surface aeration, supplemented by oxygen transfer through the reed stems.

Vertical planted bed principle

lit planté horizontal (Source : CCR Ingegnerio)

Horizontal planted bed principle

Finishing treatment of cellar effluent
Most reed bed systems treat effluent with a COD content of close to 1 gram per litre, in order to comply with discharge standards, which vary from 100 to 300 grams per bed depending on the region. The planted bed is generally placed downstream of an aerobic tank or possibly an anaerobic device combining, depending on the case, treatment of 80 to 95% to achieve a level close to 1 gram of COD per litre. In this case, in parallel with the finishing treatment, the planted bed can also degrade the sludge from the upstream biological system.

Effluent treatment by recirculation
The limited biodegradation potential of a planted bed (around 1 gram of COD/litre) can be overcome by recirculating the effluent from a buffer storage tank (without aeration). In this way, the effluent is gradually purified by successive percolations through the system (32 m³ of effluent for a surface area of 27 m² of reed bed).
Trials carried out in a small winery in the Bordeaux region demonstrated the feasibility of this system.
Depending on the initial COD level, purification can be achieved within 2 to 4 weeks.
This type of application is currently the subject of an industrial development project.

Conclusion
Planted beds, which are inspired by wetland ecosystems, can be integrated into a wide range of systems for treating cellar and spray effluents.
Their rustic design, ease of management, low energy consumption and landscape enhancement are all arguments of interest to professionals wishing to develop sustainable approaches to cellar effluents.
The finishing treatment or sludge management of systems used to treat domestic effluent is widely developed. More innovative developments (recycling, direct treatment on zeolite) offer interesting prospects for the future. As far as spraying effluents are concerned, this technique needs to be the subject of further research to optimise its design in order to manage the accumulation of copper and sulphur in particular.

Treatment of wine effluent by methanisation

Principle
Methanisation is a treatment process in which organic matter is degraded by anaerobic bacteria, in suspension or in the form of granular sludge in a closed reactor. This treatment produces carbon dioxide and methane, which is generally burnt to heat the effluent. This technique produces less sludge than aerobic processes.

How is it used?
Several processes can be applied to wine effluent: extensive processes operating at ambient temperature (methanisation tanks), extensive processes generally operating at 35°C (anaerobic filters, temperature-controlled sludge beds).
This technique does not meet the required discharge standards and must be supplemented by an aerobic treatment system (activated sludge, for example).

Methaniser

Phytoremediation

Phytoremediation is a pollution control technique that uses plants to reduce, degrade or immobilise organic compounds that pollute the soil, water or air. It is essentially based on interactions between plants, the soil and the micro-organisms present in the soil, and is used to decontaminate water loaded with organic matter or various contaminants (metals, hydrocarbons, organochlorines, pesticides).

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