Technologies for the treatment of molasses based distillery effluents

Article Index

10. Assessment of Options

The options available for the treatment of distillery effluent have been compared using a set of evaluation criteria relevant in the Indian context. The details are presented in the Table give below.

11. Observations and Recommendation

As of now, there is no adverse technological gap between India and the rest of the World in the area of distillery effluent treatment. This observation has been corroborated by the majority of respondents to the survey.

The recommendations are as follows:

(A) After the methane recovery process, the effluent is subjected to secondary treatment usually by aerobic processes. The incremental cost of operating aerobic process reduced considerably the savings generated by the methane recovery process. The methane recovery process can become an attractive economic proposition for the distilleries, and thus induce speedier implementation of newer ETPs, if the aerobic process is avoided or replaced by a more economical proposition. Several eminent scientists have recommended utilization of spent wash for irrigation purposes after primary treatment by methane recovery process.. a study ha to be carried out to ascertain the suitability of spent wash for irrigation.

Assessment of Options

Technologies

Criteria Methane Recovery Incineration (Sparnnihilator) Composting (Bioearth)

End result

- BOD(mg/l)


- Colour problem

- Odour nuisance

~1,000


Continues

Nil

~2,500
(condensate)

Nil

Nil

Claimed to be <30

Nil

Nil

Land requirement 2-3 acres <0.5 acres 25-30 acres
Capital cost ~Rs. 2.60 crores ~Rs. 3.75 crores ~Rs. 1.50 crores
Cost of operations Least High (Note 1)
Power requirement High High Nominal
Indigenous avbity of Eqpmt/know-how Yes Yes (Note 2)
Ease of operation Same degree as composting Comparatively more difficult Same degree as methane recovery
Manpower requirement Nominal Nominal High


Note:
1. The Economics of composting depend upon availability of press mud and saleability of compost at a good price.
2. Aerotiller is presently imported-expected to be indigenized in the near future.
3. Methane recovery process includes secondary treatment by aerobic processes.
4. The value are for a 50 KLPD distillery.
5. Capital cost excludes cost of land.
6. Please refer to chapters 5 & 8 for details.


(B) There are no proven viable processes for the recovery of potash from ash- a by-product of the incineration process. The economics of the incineration process would improve considerably if a suitable process is identified for recovering potash from ash.

(C) Composting (Bioearth) can become a viable effluent treatment route if(i) the cost of culture is brought down to reasonable levels (ii) the compost is popularized and sold at a higher price. A study is required to evaluate the beneficial effects of using compost produced from spent wash.

(D) The rising input costs and fiscal imposts have adversely affected the health of the distillery industry. The capital cost of an ETP is quite high. It is almost same or more than that of the main plant. Many of the distilleries are small and old. The Government should do away with all types of taxes and excise duties on ETPs so as to reduce the capital cost ETPs. Common effluent treatment facilities should be set up for treating the effluents of smaller units.

(E) The present scheme of allowing high depreciation on effluent treatment plants can be of immediate benefit to profitable units. For units which are financially weak incentives should be provided in the form of lowering of promoter’s margins, longer repayment period, lower interest rates etc.

(F) At least one model plant of each type of effluent treatment system in the country should be designed as demonstration plant. This will help in the improvement of technologies, removing apprehension regarding different technologies in the minds of the Government agencies and the industry. The results noted at such demonstration projects could act as guidelines in laying down the effluent standards and estimating the cost of effluent treatment while revising the price of alcohol.


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