|
Wastewater treatment solutions for
Distilleries
Wastewater treatment solutions for
Breweries
MOLASSES BASED
DISTILLERIES
 Molasses
based distilleries produce large amount of wastewater variously
called spent wash, vinasse, stillage or distillery slops. Depending
upon the processes used in fermentation and distillation, it's volume
varies from. 6 to 15 liters per liter of Alcohol. The characteristics
of the wastewater like COD, BOD and dissolved solids also vary accordingly.
Wastewater treatment system
for the distilleries needs to be decided based on the various factors
such as
 |
Quality of molasses and properties
of the wastewater |
|
Climatic conditions and location
of the distillery |
|
Availability of raw materials. |
|
Availability of land. |
|
Cost of fuel and electricity. |
|
Market for byproducts |
|
Pollution control norms |
Any one of the above factors
can have deciding effect on selection of the wastewater treatment
system. It is therefore essential to select the wastewater treatment
method depending upon above and choose the suitable fermentation
and distillation process accordingly.
In other words cane molasses based distillery and it's wastewater
treatment system should be made for each other. With one or
more options from the basket of technologies available (see diagram),
a system can be conceptualized and designed for requirement of distillery
complex OR with resources available at distillery site/location
for disposal of fina treated effluent.
EVAPORATION
Flubex* (Fluidized Bed)
Evaporation
Falling Film Evaporation
Forced Circulation Evaporation
Flubex Evaporation
Huge volume of wastewater from the mash column
can be reduced to more than 80 % by concentration. The concentrated
product can be used :-
|
All conventional Evaporation
systems face problems of frequent scaling, fouling and hence
require rigorous manual cleaning to maintain rated evaporation
capacity.
On the other hand, the In-house development by PRAJ
uses patented Fluidized Bed Heat Exchangers "FLUBEX",
with self cleaning function, eliminating the above disadvantage
and ensuring trouble free concentration. FLUBEX comprises
of the vertical tubular heat exchanger, in which fluidizing
media is added to impart gentle scouring action on internal
tube surfaces, while moving upward with the liquid being evaporated.
|
|
The Patented Flubex heat exchanger
can be used in multiple effect evaporator system and has several
unique advantages for wastewater concentration applications.
|
Best for concentration of fouling
Liquid wastewater. |
|
Minimum down time and consistent
performance |
|
Requires minimum cleaning of heat
exchangers |
|
Economy of steam consumption due
to multiple effects |
Biomethanation using Ecomet
XTR
 |
Anaerobic biomethanation system
uses a specially designed Mixed Tank Biodigester; called
Ecomet XTR,
to convert organic matter into useful energy in the form of
Biogas. The biological process of conversion takes place at
Mesophilic temperature in a controlled atmosphere ensuring maximum
conversion efficiency & production of Biogas. Ecomet XT
is specially designed to handle highly toxic distillery waste
taking into account the suspended solids, toxic compounds &
high COD and BOD in spent wash, shock loads arising out of distillery
operation and variations in feed characteristics, variation
in temperature conditions. Various features of Ecomet XT
system give following benefits.
|
| HIGHLIGHTS of ECOMET-XT
Biomethanation System |
|
Special geometry of the Reactor with unique
design of the Mixing System ensures excellent mixing of organic
matter with suspended biomass ensuring optimum reaction time.
|
|
The hydraulic retention time enables higher
COD loading without dilution, reducing water consumption and
further cost of treatment/disposal. It also avoids shock loading
and malfunctioning of the reactor.
|
|
Scientifically designed parallel plate clarifier
system for separation and recycle of biomass to reactor maintains
optimum biomass quantity thereby ensuring maximum biogas generation.
|
|
Design of sludge receiving and settling system
prevents buildup of inorganic solids in the reactor leading
to consistent performance over a longer period.
|
|
Minimum reactor internals prevent build up
of inorganic sludge ensuring maximum utilization of reactor
volume over longer period.
|
|
Proper heating and cooling systemprovided
to ensure consistent performance even during winter season.
|
Bio Composting
|
A lot of work has successfully been done
by PRAJ in the field of composting. Composting is process
of converting organic matter into manure, rich in humus and
plant nutrients.
This alternative of utilizing digested/raw spent wash in combination
with press mud/filter cake from sugar mill has been widely
accepted and implemented. Praj can support in conceptualizaion
of biocomposting plant.
|
|
The wastewater from the distillery
in raw or concentrated form or from the Biogas plant can be further
treated in the Composting system. Like biomethanation, biocomposting
is also a biological process and needs a system, which will provide
food, air, and moisture in appropriate quantity to the organisms.
Hence the design of mixing and aeration system, the cycle of operation
are of paramount importance for optimum results.
To avoid ground pollution, spent wash is sprayed in a controlled
manner on the windrows, which are formed on the fields by composting
machine driven by tractor. A proper leachate management system in
and around the compost plot to take care of flooding in rainy season
is important. Ground surface has to be made suitable to facilitate
vehicular movement.
A well-designed Bio-composting
process can ensure zero pollution when enough Press Mud as filler
material is available and process norms are strictly adhered to.
It is the most cost-effective solution available when weather conditions
are favorable.
STARCH BASED DISTILLERIES
DDGS
Wheat / Rice / Sorghum/ Cassava
is used as a raw material for ethanol fermentation. It contains
starch, which can be enzymatically converted to simple sugars and
made available to yeast for fermentation.
After conversion of sugars to ethanol
during fermentation, remaining ingredients like proteins, other
inorganic solids and unfermented sugars are present in the wastewater.
The wastewater is called as stillage or slops.
It is possible to convert slops into
useful value added product called Distillers dried Grain solubles
(DDGS) which is used as cattle feed supplement / additive. This
product while improving upon the overall VIABILITY of the
distillery also takes care of wastewater in most effective manner.
The thick slops from mash column is cooled
and passed through decanter Centrifuge for solid - liquid separation.
The liquid coming out from decanter is called thin slops and the
solid portion is called wet cake. Part of thin slops is recycled
to the Fermentation process. This effectively reduces the wastewater
load.
The thin slop from Decanter is concentrated in
multiple effect Forced circulation Evaporators to produce thick
slops. The wet cake from decanter & thick slops from Evaporator
is mixed in screw conveyor before drying. The drying of the mixture
is carried out in dryer. The final product collected is DDGS. Which
is used as cattle feed supplement to generate revenue.
Evaporation and drying option gives non-molasses-based
distilleries a zero pollution option coupled with water conservation.
Biomethanation and aeration
 Thin
slops coming out of decanter can be alternatively treated using
combination of biomethanation and secondary aeration treatment methods.
Anaerobic biomethanation system uses a special reactor, called Biodigester,
to convert organic matter into useful energy in the form of Biogas.
The biological process of conversion takes place at Mesophilic temperature
in a controlled atmosphere ensuring maximum conversion efficiency
& production of biogas.
The biomethanated wastewater from the biomethanation plant mixed
along with other wastewater streams from distillery such as spent
lease; condensate water and floor washings are treated in the Secondary
Aeration System. This system comprises of two stages namely Conventional
Activated Sludge System followed by Extended Aeration System.
The liquid coming out of secondary aeration system can be further
treated by tertiary activated carbon filter and chlorination or
sent to common wastewater treatment plants or used for irrigation.
Alternatively reverse osmosis membrane systems can be employed for
recovery of water and reuse.
Brewery requires treatment before
it can be used as water for irrigation. The treatment method comprises
of Biomethanation followed by aeration or a two stage aeration system.
The former method has advantage of less power consumption and less
sludge generation while the latter has advantage of easy start up
and operation. While PRAJ can provide both types of system, considering
the overall benefits biomethanation followed by aeration system
is recommended.
Biomethanation & Aeration
Brewery wastewater though very weak in nature poses typical
problem of fluctuating loads and characteristics due to various
cycles of operations. The treatment method needs to be designed
to cater to such fluctuations without affecting the output parameters
of the wastewater treatment system.
Anaerobic biomethanation system uses a special reactor, called Biodigester,
to convert organic matter into useful energy in the form of Biogas.
The biological process of conversion takes place at Mesophilic temperature
in a controlled atmosphere ensuring maximum conversion efficiency
& production of biogas.
The biomethanated wastewater from the biomethanation plant mixed
along with other wastewater streams from brewery such as condensate
water and floor washings is treated in the Secondary Aeration System.
This system comprise two stages namely, Conventional Activated Sludge
System followed by Extended Aeration System. The wastewater can
be discharged to common wastewater treatment plants or can be further
treated before recycling by employing activated charcoal and chlorination
techniques. Alternatively reverse osmosis membranes can be employed
for water recovery and recycle. Sludge drying beds need to be provided
for drying of sludge.
Yeast Dryers
The process produces Spent Yeast
Powder of about 10 % moisture content from feed spent yeast with
solids content of 13 - 15% w/w. The process utilizes heat treatment
of Spent Yeast at 80°C for a fixed time period by which cell
components are solubilized by activation of the degradative enzymes
inherently present within the cell. This treatment causes death
to the yeast population without inactivating the degrading enzymes
that remain compartmentalized in live cells. This is called autolytic
process under which yeast cells begin to die after all the cell
reserves have been used up.
After this preheat treatment, Spent Yeast is
fed to double drum dryer which evaporates the moisture and produces
spent yeast powder which is protein rich and is used as animal feed.
|
