Agriculture Reference
In-Depth Information
One of the reasons limiting the spread of the biotechnology industry is the production of
wastes, e.g., vinasse, which are difficult to dispose off. The large amount of vinasse can be
utilised as fodder which partially solves the problem.
Vinasse constitutes a high volume and high strength acidic waste so that disposal of
untreated vinasse to natural waterways is not feasible [Sheehan and Greenfield, 1980].
Vinasse is probably the strongest of all industrial wastes in terms of its polluting load
specially B.O.D. Average B.O.D of vinasse from a molasses distillery is about 35000ppm. A
small distillery discharging only 50,000 gallons of vinasse per day can contribute a B.O.D
load equivalent to the sewage of a town with 100,000 inhabitants. To maintain about 3ppm
dissolved oxygen in the stream receiving vinasse, minimum dilution required is 11660 times
that of the vinasse or about 11000 cusec (cubic feet per second) of water [Chakrabarty, 1964].
Vinasse can pose significant threat to fish. LC50 values of vinasse that can kill different fish
species in 96 hours are reported in Verma and Dalala [1976].
Vinasse, typically, contains a high concentration of potassium, calcium, chloride and
sulphate ions. Inorganic constituents present in vinasse are given in Table 3. Ash from the
combustion of vinasse contains about 37% K
2
O and 70 - 73 % of the ash is soluble in water.
Potash is present as sulphates, chlorides, sulphides and carbonates. The average distribution
of potassium salts in the ash is given in the Table 4 [Sheehan and Greenfield, 1980].
Different options have been tried or proposed to utilize vinasse. Possible outlets for this
by-product could be composting, fodder, filler in paper, cattle feed, methane production by
anaerobic fermentation, fertilizer (high K content), as a binder in briquetting and
combustion.Volume of stillage can be reduced by recycling which also removes some of the
organic and inorganic constituents [Sheehan and Greenfield, 1980]. About 50% of the stillage
can be recycled [Dubey, 1974]. Stillage can be applied to land as a fertilizer to increase its pH
because high Ca and Mg improves physical and chemical properties,mineral and water
containing characteristics and fertility of soil [Sheehan and Greenfield, 1980]. A number of
studies have been devoted to assess the feasibility of vinasse as a fertilizer e.g., Ross et al.
(1938), Sastry et al. (1964), Guimaraes et al. (1968), Dubey, (1974), Khruslova et al. (1974),
Cooper, (1975),Jackman, (1977), Gloria, (1977) Bieske, (1979) and Usher and Willington,
(1979). For economic disposal of vinasse as a fertilizer a large land area adjacent to the
distillery is required and should be in a low-medium rainfall region which is highly unlikely
in the UK. Moreover there are huge costs of piping network [Sheehan and Greenfield, 1980].
Table 3. Inorganic constituents in molasses stillage (g/kg)[Bieske, 1979]
Australia
Brazil
Component
Millaquin distillery
Average (1976)
Ash
32
19.2
N
3.1
0.9
P
0.02
0.05
K
8.6
4
Ca
1.1
1.8
Mg
1.5
0.5
