Agriculture Reference
In-Depth Information
Box 5.5 Amounts of Organic Waste from Wineries and Its Beneficial Use
Depending on the efficiency of the winery, a crush of 1000 t grapes produces
between 1 and 3 ML wastewater. On average, the wastewater comprises 99%
water and 1% solids (dissolved and particulate), most of which is organic matter.
Thus for every 1000 t grapes producing, say, 2 ML wastewater, there is about 20
t of readily decomposable organic matter that can be recovered, composted, and
applied to the soil. Separating the solids and water provides a source of water for
irrigation.
For small wineries (<500 t crush), a favored option for water treatment
is filtration through a wetland—for example, a
Phragmites
reed bed that
removes much of the organic matter. The filtered water can then be used for
irrigating nonvineyard land, such as pastures or woodlots, or can be blended
with good-quality water at a ratio of about 1:10 and used to irrigate vines. Such
filtration beds are expected to last up to 15 years before needing to be regenerated.
For intermediate-size wineries, the FILTER system developed by the
Australian Commonwealth Scientific and Industrial Research Organization
is a possibility (
www.clw.csiro.au/publications/projects/projects20.pdf
). Tile
drains (perforated PVC pipe) are installed at 1-m depth and 10-m spacing in the
water disposal area, which is divided into bays for flood irrigation. Much of the
organic matter is retained in the soil as water percolates to the drains. However,
dissolved salts also leach into the drainage water, which must be pumped into
evaporation ponds. The soil under the FILTER system retains more than 80%
of the wastewater N and P. The amount of water that can be applied in a season
depends mainly on the soil texture. Clay soils tend to seal with the organic matter
applied and may only accept up to 250 mm per year (0.25 ML/ha/year), whereas
sandy soils may accept up to 1500 mm (1.5 ML/ha). In the latter case, for a 1000-t
winery, about 3 ha of land would be required.
Approximately 10% of the crush goes into marc so that 100 t marc is
produced per 1000 t grapes crushed. Although this material is not so readily
decomposed, it can be composted at the winery site (see figure 3.15, chapter 3) and
applied to the soil. In Australia, most of the marc from larger wineries is extracted
to remove residual alcohol and K tartrate, dried, and pelleted for use as stock
feed or soil conditioner. As a stock feed, it has almost half the nutritive value of
feed-quality barley.
of reclaimed sewage water in vineyards. Table 5.11 gives the range of dissolved
salt and nutrient concentrations in winery wastewater. Likewise, the
TDS
of
reclaimed sewage water, measured by the
EC
, is usually between 1.5 and 3 dS/m.
Because sodium hydroxide (NaOH) is commonly used as a cleaning agent
in a winery, the
SAR
of wastewater is raised, and, over time, this can create soil
structural problems, either at the disposal site or where the water is used for pro-
ductive irrigation. To counter this problem, gypsum should be applied to the soil
at regular intervals. As the gypsum dissolves, Ca
2+
ions are released and the
SAR
of
