Monday, October 3, 2022

Press Mud is a potential fuel of the future and sustainable Fertilizer.

 

The Indian sugar industry is like the Kalpvriksha as during its processing yields products and co-products which has significant values in the market. Over the year utilization pattern of these products has undergone significant change due to various reasons in and around the sugar industry. The prices of sugar can been traditionally decided by the Indian sugar policy and as of now its is FRP based system which effectively linked to sugar recovery via various means / products like sugar, sugar syrup, molasses B-heavy grade etc but not limited to. As per Indian sugar policy latest edition the revenue from sugar and its co-products such as bagasse, Molasses, and Pressmud shall be shared with farmers. The Indian biofuel policy 2018 and its subsequent amendment / update enabled Indian sugar industry to use its products and co-product in more productive ways than before . This collectively contributed to increase in farmers income in quite significant way in recent past.
Almost all the co-product from sugar mill are used quite innovatively which somehow linked to the national interest of energy requirement at one end and the farmers income enhancement on other. Sugar, Molasses and Bagasse added significant value to Indian sugar industry over the years. Whereas another co-product which is slightly underutilized so far in content to extent of value other product added.
Pressmud which is commonly known as filter cake or press cake in sugar industry. It is residue of juice clarification process where main product is clear juice and impurities settled at bottom then filtered traditionally using rotary vacuum filter. In rotary vacuum filter all best possible efforts for recovery of sugar is made and final filtered residue is called filter cake or press cake. Typical generation of pressmud is about 3-5 to 4+% w/w of the cane crushing capacity of the mill. During this filtration process bagasilo is added as filter aid which is nothing but fine bagasse particle made this method of filtration very popular in the sugar mill due to no additional expenses of filter aid. In recent past there are some mills who tried using centrifugal decanter for separation of mud /cake from juice clarification process but due to multiple reasons it fail to impress the industry.
Press mud is basically a mud i.e. dirt and good amount of bagasilo and inorganic impurity courtesy to clarification process in sugar mill. Way back when distilleries were only used for potable alcohol production majority of pressmud was distributed to farmers who used it as organic fertilizer in sugar cane fields. When the when Ethanol was projected as Biofuel and various schemes to push to enhance production Ethanol then bio-composting using press mud as prominent substrate is gain boost as method of zero liquid discharge apart from other measure to ensure the zero pollution from distilleries. Evacuation of bio-fertilizers was one the major challenge in this method of spent wash treatment which in most of the cases became expense to such industries rather than became value added co-product. It might have solved the sugar mill press mud evacuation issue but it just got shifted to distilleries. The multifold increase in sugar mill capacities changed the dynamics of the press mud utilization in recent past. As a result which was supposed to be one of the potential co-product confined to as intermediate which generally transferred from sugar mill to some way of utilization or treatment at either unsold value or notional value.
As govt of India drafted a biofuel policy in 2018 for both liquid and gaseous fraction of green, clean and indigenous biofuel which will significantly contribute to countries energy security. Compressed biogas was seen one of the major gaseous biofuel which will solve multiple national issues and convert them to opportunity. The government of India has launched the SATAT ( Sustainable alternative toward affordable transportation) program which will target setting up about 5000 Compressed Biogas plant which potentially suffice the natural gas requirement to the greater extent while solving pollution issue of country.
The SATAT program enabled Indian entrepreneur to come up with innovative ways of extracting biogas from low value raw materials and covert them to value added co-products like fuel and fertilizers. As mentioned in my previous article ( link- https://www.linkedin.com/pulse/feedstocks-compressed-natural-gas-production-bharat-kadu/) the best possible feedstock for biogas / Compressed biogas Gas (CBG) Production shall have following attribute but not limited to.

1.      Higher Window of availability
2.      Ease of Access and assured supply
3.      Minimal Transport and handling requirement
4.      Decent Yield of product and by-product
5.      Relatively Ease of conversion
6.      Benefit to society and their involvement in the process
Looking at feedstock under consideration press mud became one the most popular choice of the project developers even though there is huge push for rice straw and other agri residue.
At present sugar industry encashed Pressmud whenever opportunity is there on an average value of 100-400 Rs/MT which is about 4 to 16 Rs/MT of cane crushed. IF this Pressmud is used in bio-composting with Pressmud then Pressmud contribution of fertilizer is appx. 200-250 kg per MT of press mud used and average Bio-Composting selling price is 700-1000 Rs/MT which results in appx value realization of about 140 to 400 Rs/MT excluding cost of production which is generally higher than the selling price as prime objective manufacturing such biofertilizers is compliance to Zero liquid discharge requirement of distillery effluent not the production of fertilizer.
In recent past due to exponential increase in coal prices the cheaper alternative demand has gone up significantly. The Pressmud in some cases is sun dried and converted to pellets which can substitute some of the high cost fuel in short term resulted in demand for Pressmud for the application other than bio-composting.
One ton of average specification of press mud if converted to CBG then appx. 40 kg or CBG is produced along with about 110-130 kg of solid biofertilizers and 500-700 lit of liquid fertilizer. The Solid fertilizer market selling price is about 2.5 to 3.0 Rs/Kg and as per latest CBG pricing & Retail selling prices of CNG one can expect min 65 Rs/kg for CBG as safe bet. The Revenues from such conversion adds up to about 3000 Rs/MT of Pressmud. The potential revenue from press mud to CBG could be about 120 Rs/MT of Cane crushing which is significantly higher than what we are getting as on of now.
The better value utilization of Pressmud will definitely resulting in significant increase in farmer’s income if the benefits passed on to farmer ensuring sustainable CBG manufacturing business which will result in win-win for all the stockholder of the value chain.
Please note these are just estimated number which moving forward needs to be evaluated for specific case which will largely cover the situation in most of the mills of India.
This will enable all sugar mills to become a true bio-refinery which will be significant pillar of Indian food and energy security apart from connecting millions of farmers to building nation which is self-sufficient and making India the Next Super power. 

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