DISTILLERY WASTE WATER TREATMENT
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Distilleries produce alcohol; alcohol may be used for various purposes, e.g. to produce potable alcohol, alcohol for blending with gasoline, or alcohol as a feedstock for a variety of downstream chemicals, chemical intermediates, as fuel for automobiles – gasohol. etc.
The first known Indian distillery was established in 1805 at Janjmow, Kanpur in (U.P).
At present there are about 319 distilleries in India with an installed capacity of more than 3250 million liters of alcohol production per annum.
About 15 liters of waste water is produced per liter of alcohol production.
In general, distillery wastewaters are acidic, have a brown color due to the pigment called “melanoidin” which is refractory in nature to the biological treatment.
PRODUCTION OF ETHYL ALCOHOL
The manufacturing process for molasses based ethanol consists of following stages:
Yeast propagation and Continuous fermentation
Multi-pressure distillation with integrated spent wash evaporator
Molecular sieve dehydration for fuel alcohol
ELECTRO COAGULATION METHOD
In the EC process, the coagulant is generated in situ by electrolytic oxidation of an appropriate anode material. In this process, charged ionic species—metals or otherwise—are removed from wastewater by allowing it to react (i) with an ion having opposite charge, or (ii) with floc of metallic hydroxides generated within the effluent.
The EC technology offers an alternative to the use of metal salts or polymers and polyelectrolyte addition for breaking stable emulsions and suspensions.
The technology removes metals, colloidal solids and particles, and soluble inorganic pollutants from aqueous media by introducing highly charged polymeric metal hydroxide species.
PRINCIPLE OF REVERSE OSMOSIS:
Pressure is applied to saline water to force the pure water molecules through a semi-permeable membrane. The majority of dissolved salts, organic, bacteria and suspended solids are unable to physically pass through the membrane and are discharged form the system in the rejected brine. The pure water is then ready for use without further treatment
Removes nearly all contaminant ions and most dissolved neg-ions,(Mg2+,Ca2+,SO42-,Na+,color),
RO operates immediately, without any minimum break-in period,
Low effluent concentration possible,
Bacteria and particles are also removed, and Operational simplicity and automation allow for less operator attention and make RO suitable for small system applications.
USE OF DISTILLERY EFFLUENT IN AGRICULTURE
The effluent contains high potassium (1.3%) and sulphur (0.4%) and appreciable amounts of nitrogen (0.2%) and acts as a slow release fertilizer being mostly in the colloidal form. Moreover, it contains large amount of calcium, copper, manganese, zinc and a substantial quantity of organic matter essential for soil health. So it can be applied directly to the land as irrigation water as it helps in restoring and maintaining soil fertility, increasing soil micro flora, improving physical and chemical properties of the soil leading to better water retaining capacity of the soil. The effluent is ideal for sugarcane, maize, wheat production.
Being very rich in organic matters, the utilization of distillery effluents in agricultural fields creates organic fertilization in the soil which raises the pH of the soil, increases availability of certain nutrients and capability to retain water and also improves the physical structure of soil.