From Field to Bottle: Water Footprint Estimation …
111
represent point-source discharges of contaminants entering the natural environment,
non-point sources of pollution to natural water bodies are an important consideration
when assessing the environmental impact of wine-making on local water resources.
This section reviews the main sources of point and non-point-source contaminant
discharges, as well as an overview of current winery wastewater handling, treatment
and reuse strategies used at full scale.
4.1 Wastewater During Viticulture
The main source of wastewater in viticulture is drainage and runoff from the vineyard, which can contaminate both surface and groundwaters as a non-point source
of pollution. Typical compounds of concern include nutrients, such as nitrogen and
phosphorus, and chemicals applied for pest control, including pesticides and herbicides. Pathways for contamination include runoff to surface body waters, or drainage
through the overburden into groundwaters. In addition to pesticides and nutrients,
sediments can also be found in vineyard runoff [7], which can contribute to heavy
metal and turbidity pollution of local waterways. Pesticides and herbicides applied to
the vineyard can also be prone to drifting, which can result in their ultimate deposition
into and pollution of nearby surface waters [25].
Due to their nature, pesticides and herbicides can have toxic impacts at very low
concentrations. Reducing their discharge to the environment can substantially reduce
the environmental impacts of vineyard operations. Recent advances to reduce loadings to the environment include the development of natural, biological approaches to
pest control. Planting hedgerows at the edges of the vineyard are effective at controlling drift, with a mature hedgerow able to reduce drifting by up to 75% [39]. In
addition, the application of some pesticides can be reduced or eliminated by flowering plants that attract the predators of pests, while other options include allowing
higher order predators, such as ducks and geese, access to the vineyard [25]. Such
biological approaches can, however, take 4–5 years to become fully effective.
Physical barriers applied to the vine trunks can also prevent insects from reaching
the leaves and fruit, reducing the need to apply pesticides. When treatment is needed,
more precise pesticide application methods (such as directed spraying) and spray
techniques can also reduce drifting. Reductions in drifting of up to 50–90% are
possible when using precision instruments or tunnel sprayers, respectively, versus
conventional nozzles [39]. Better weather forecasting also allows more precise timing
of application, which can be particularly useful to reducing the application rates of
chemicals used for mildew control such as sulphur, copper sulphate and lime [25].
Nutrients in agricultural runoff are a concern for the health of local surface waters.
Two key nutrients required for plant growth, phosphorus and nitrogen, can promote
eutrophication and are often added as fertilizers to crop land. Phosphorus fertilizers
are used mainly for younger vines, with older vines requiring less phosphorus [61],
reducing long-term fertilization needs. Legumes planted as cover crops also provide
111
represent point-source discharges of contaminants entering the natural environment,
non-point sources of pollution to natural water bodies are an important consideration
when assessing the environmental impact of wine-making on local water resources.
This section reviews the main sources of point and non-point-source contaminant
discharges, as well as an overview of current winery wastewater handling, treatment
and reuse strategies used at full scale.
4.1 Wastewater During Viticulture
The main source of wastewater in viticulture is drainage and runoff from the vineyard, which can contaminate both surface and groundwaters as a non-point source
of pollution. Typical compounds of concern include nutrients, such as nitrogen and
phosphorus, and chemicals applied for pest control, including pesticides and herbicides. Pathways for contamination include runoff to surface body waters, or drainage
through the overburden into groundwaters. In addition to pesticides and nutrients,
sediments can also be found in vineyard runoff [7], which can contribute to heavy
metal and turbidity pollution of local waterways. Pesticides and herbicides applied to
the vineyard can also be prone to drifting, which can result in their ultimate deposition
into and pollution of nearby surface waters [25].
Due to their nature, pesticides and herbicides can have toxic impacts at very low
concentrations. Reducing their discharge to the environment can substantially reduce
the environmental impacts of vineyard operations. Recent advances to reduce loadings to the environment include the development of natural, biological approaches to
pest control. Planting hedgerows at the edges of the vineyard are effective at controlling drift, with a mature hedgerow able to reduce drifting by up to 75% [39]. In
addition, the application of some pesticides can be reduced or eliminated by flowering plants that attract the predators of pests, while other options include allowing
higher order predators, such as ducks and geese, access to the vineyard [25]. Such
biological approaches can, however, take 4–5 years to become fully effective.
Physical barriers applied to the vine trunks can also prevent insects from reaching
the leaves and fruit, reducing the need to apply pesticides. When treatment is needed,
more precise pesticide application methods (such as directed spraying) and spray
techniques can also reduce drifting. Reductions in drifting of up to 50–90% are
possible when using precision instruments or tunnel sprayers, respectively, versus
conventional nozzles [39]. Better weather forecasting also allows more precise timing
of application, which can be particularly useful to reducing the application rates of
chemicals used for mildew control such as sulphur, copper sulphate and lime [25].
Nutrients in agricultural runoff are a concern for the health of local surface waters.
Two key nutrients required for plant growth, phosphorus and nitrogen, can promote
eutrophication and are often added as fertilizers to crop land. Phosphorus fertilizers
are used mainly for younger vines, with older vines requiring less phosphorus [61],
reducing long-term fertilization needs. Legumes planted as cover crops also provide