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A.
Background:
The article is intended to enlighten
the availability of press mud for CBG production in India and competition from
alternate usage today and tomorrow.
The press mud is combination of two
world press and mud which has a history attached to it. The sugar cane juice
after extraction from cane undergo pasteurization process to disinfect any
presence of bacterial infection before further processing. The Sterilized juice
then treated for removal of mud, organic precipitates which come along the
juice extraction process apart from high molecular weight complex sugars which
will interfere in production of sugar at later stage of the processing. It
literally means the mud recovered from juice clarification is mechanically
pressed to recovery maximum possible sugar from it in equipment called Rotary
vacuum filter (R.V.F.). The press mud is also called as “maili” in Hindi which
means soil contaminated stream. R.V.F. is widely used equipment which needs
addition of bagasilo as filter Aid traditionally which are fine bagasse
particles which impart cellulose and hemicellulose fractions in Pressmud. These
fraction are the only digestible fraction apart from residual sugar in it which
is explored for generation of biogas in recent past.
There is one more method rose to
fame of mud separation by decanter which due to its inherent limitation haven
not received well by most of the sugar factories which separate the mud without
requirement of any filter Aid and pressmud from such sugar factories known to
yield negligible biogas in various runs by researchers at various levels.
B.
Pressmud Production trends and
Present usage
The Indian avg sugar production in
recent past is about 30-32 MMT and Our sugar cane crushing is about 350-400 MMT
on about 500 sugar factories across India. The values could vary here and there
a bit but the trend will prevail mostly. The Indian in house sugar consumption
is about 25-26 MMT and by an average we used to have roughly 6-7 MMT of sugar
is in excess every year in recent past till govt allowed the production of
Ethanol under EBP and farmer cane arrear issues built-up apart from cash
outflow on export subsidy.
The average pressmud production as
per production at 3.5 to 4% w/w of the crushing will stand at 12 to14 MMT per annum.
The most prominent use of pressmud
in the history and at present is for bio-composting distillery spent wash which
limited the Ethanol production over the years and NGT actions leading to push
for ZLD in distillery which is one of the most polluting red category industry.
India has more than 350 distilleries
producing about 5-6 Billion liters of Ethanol from sugar bearing feedstock
which lead to about 50-60 Billion liters of effluent for disposal.
In recent past Ethanol production
has grown mainly on account of incineration boiler for ZLD which reduced
requirement of pressmud for composting. Roughly 1-1.5-Billion-liter capacity
has Incineration boiler and balance are having Biomethanation route of ZLD with
Composting. The effluent disposal of about 4 to 4.5 billion liters worth
production literally needs about 10-11 billion liter effluent disposal and at
1-1.5 composting ratio it demands 8-11 MMT pressmud. Which is largely equal to
total production in India.
As most of the distilleries shifting
to non-composting sustainable route of effluent Managment due PCB pressure and
need for increased production due to push from Govt for EBP the pressmud is
gradually freeing up. There is slight stagnancy in the plant going for incineration
boiler in recent past due to drastic reduction in effluent generation due to
use of high sugar bearing fractions from sugar mill for production of Ethanol.
This situation lead to impact on economic viability of incineration boiler as a
mode of ZLD and exploration of other mode of ZLD a need of the hour.
At the same time spent wash
nutrients must go back to sugar cane fields because major nutrient is Potassium
which is in abundance in spent wash. Unfortunately India has 100% import of potassium
in the tune of 2.5 to 3 million Mt. We have about 5.3 million hectors of Area
under cane plantation. The avg. potassium requirement of plant is about 90 to
100 kg/Ha which translate to about 0.53 million Mt i.e. about 20% of the import
could be saved by effective use of spent wash as a fertilizer via bio-compost
or any other rout of recycling spent wash to cane fields.
As most of the consumption is for
composting in their own distillery or offtake by some standalone distillery
unit in some cases never ever stressed / posed press mud as a disposal issue
and if some small quantity demand disposal then storage in yard for 20-30 days
reduces its volume by 1/3rd which reduced the scale of issue as off
now.
So with this back ground whosoever
speaks to sugar industry they will not project pressmud as issue due to
in-house consumption avenues and excess if any at location could be used for
building relation with farmer by giving it to them as Fertlizer.
However, spent wash bio-composting
is still a mode of spent wash disposal than fertilizer production facility. The
profitable ways of fertilizer offtake and marketing is still a challenge to address
to the greater extent.
As the mud portion is coming from
Farm and anyways goes back to farm as humus after composting. The bagasilo portion which is Actually part
of bagasse has organic which could be converted to biogas which slightly
difficult ways than selling it as fuel in local brick kilns in UP and other
part of India was a regular affair for disposal as offtake was always been
issue for bulk quantities until NGT crackdown on such kilns on pollution aspect
in northern India.
As more and more distillery will
shift to non-composting based ZLD routes pressmud will gradually open up and
build as issue for disposal if not converted to Biogas in coming time.
The surplus sugar has potential to
produce about 3.5 to 4.5 Billion liter of Ethanol as of now where as our
requirement based on NITI Aayog projection will be over 10 Billion liters which
need a serious after though about feedstock’s and technology if our internal
sugar consumption not gone down to free up the extra sugar or innovative
farming technology which will increase the sugar cane yield for EBP in near
future which looks one of the major challenge and hurdle in the Ethanol boom to
sustain in near future.
C.
Future usage of Pressmud and facts
EBP is been significant part of
Indian energy dashboard in recent part and industries along with technology
suppliers looking out to various feedstock which could be potentially converted
to Ethanol or liquid biofuel economically.
Pressmud could be converted to
pellets for combustion after drying by small sugar factories is near future due
to restriction on composting and unviability of CBG plant due to viable capacity.
Pressmud like high ash fuels will pose its own challenges in disposal for sure
but due to disproportionate increase in coal prices use of pressmud for fuel
gained lot of traction in recent past. How sustainable way of utilizing
pressmud is to be seen in near future with overall impact of environment.
Bagasse could be one of the
potential product moving forward can be converted to CBG as Power PPA has seen
downward trends in recent past and no significant upward movement is expected
in time to come. However existing investment in co-generation plants will
largely limit this shift considering majority of investment in cogeneration
plants is on BOOT basis. The avg available free bagasse in today’s scenario is
about 10-20 MMT which is mostly used as fuel, paper and board manufacturing
India at on date.
As paper and board are value selling
products can afford cost variations apart from fuel application at some
locations so overall project economics will drive its conversion to various
byproducts in near future. The is possibility of conversion of bagasse to 2G
ethanol at prohibitive price for private investor as on date and any update
moving forward will be interesting to watch out. These value are really good
indicator for industry to chalk out the business goals in near and immediate
future.
I personally feel use of pressmud
and bagasse to extract maximum value by converting it to CBG for mills would be
potential option to evaluate.
D.
Conclusion and Recommendations
moving forward
a. Pressmud will pose major disposal
issue in near future if not converted to value added co-product such as CBG by
sugar industry.
b. Pressmud and bagasse to Ethanol using 2G Biomass to
Ethanol technology being lignocellulose based substrate and overall process
will be distance possibility and troublesome due to handling and investment
number in such technology.
c. Pressmud will be available more and
more in coming future as NGT will tight grip on red category industry looking
at present ZLD technology credentials apart from Slop fired boilers which is
largely a known devil in ethanol industry.
