NUTRIENTS
FROM SPENT WASH - SCI & TECH
News:
Bhavnagar lab develops
tech to separate potash fertilisers from spent-wash ash
What's
in the news?
●
The Central Salt and Marine Chemicals
Research Institute (CSMCRI) at Bhavnagar in Gujarat has developed a process to recover both sulphate of potash
(SOP) and muriate of potash (MOP) from the spent wash ash generated by
sugarcane molasses-based distilleries.
Spent
wash:
●
Spent wash is basically the wastewater or
effluent that is a byproduct of alcohol
production.
●
For every one litre of alcohol that they
produce from fermented cane molasses, distilleries generate 10-15 litres of
spent wash.
Nutrients
in spent wash:
●
Spent wash contains about 2-3 percent potash and a huge organic load and
salts that, if discharged without treatment, can pollute both land and
water bodies.
Recovery
of nutrients from spent wash:
Since distilleries are
required to adhere to zero-discharge norms imposed by the Central Pollution
Control Board, they manage the spent wash mainly by two methods:
1.
Mixing with press-mud:
●
By mixing it with press-mud from sugar mills, the cake is a residual cake after
clarification and filtration of cane juice.
●
This mix is then composted and converted
into manure.
2.
Feed in incineration boiler:
●
To concentrate the spent wash to 58-60
percent solids and feed it into an incineration boiler.
●
The resultant ash coming out of the boiler
in dry form contains 20-21 percent
potash and, in some cases, it is converted into granules for agricultural
application.
Go
back to basics:
Central
Salt and Marine Chemicals Research Institute (CSMCRI):
●
The CSMCRI is one of the 37 premier
national laboratories functioning under the aegis of the Council of Scientific and Industrial Research (CSIR), the apex
research and development organisation headed by the Prime Minister.