1. Electrocoagulation and Coagulation of Distillery Spent Wash Effluent
EC of Distillery Spent Wash
6/10/2018
Vinita Khandegar and Anil. K. Saroha*
Department of Chemical Engineering
Indian Institute of Technology Delhi, India
Textile industries are one of the most polluting industries in terms of the volume and complexity of its effluents discharge.
The dyeing and finishing operations in textile industries contribute a major share to wastewater generation.
So that I have taken interest in treatment of textile industry effluent using electrocoagulation.
15 December 2012

2. Distillery Industry Demand for alcohol is likely to increase
India is the fourth largest producer of ethanol in the world and the second largest in Asia.
India produces about 3.25 billion litres of alcohol annually.
Applications of ethanol
Potable liquor (spirit and beverage)
Industrial alcohol (drugs, rubber, pesticides, solvents, pharmaceutical and flavouring)
Demand for alcohol is likely to increase
Chauhan, M.S., et al., International Conference on Future Environment and Energy, Singapoore,, , (2012).

3. Water Pollution Problems in Distillery Industry
The distilleries are listed at the top in the “Red Category” industries having a high polluting potential.
There are 319 distilleries in India producing 3.25 billion litres of alcohol and generating 40 billion litres of spentwash annually
Tewari, P.K. et al., Resour. Conserv. Recycl., 52, (2007).
Uppal, J., Proceedings of the Indo-EU workshop on Promoting Efficient Water use in Agro-based Industries, New Delhi, 12-15, (2004).
Selvamurugan, M., et al., J. Bio. Sci. 11(6), , (2011).

4. Generation of effluent from Distillery Industry
Spentwash From Distillation Column
Spent Lees From Analyser Column
Other wastewaters like fermenter washings, fermenter cooling, floor washings, spillage and cooling.
10-15 litres of spentwash is generated for every litre of alcohol produced

5. Potential polluting agent because
Spentwash
Waste water (spent wash) generated by distilleries during the distillation and fermentation of molasses to ethyl alcohol using specific strains of yeast.
A dark brown coloured liquid
Containing residual nutrients from sugarcane and yeast cells
Does not contain any heavy metals or other toxic residues
Potential polluting agent because

6. Characteristics of distillery spentwash
Parameters
Values of distillery effluent pH
3.0–4.5
BOD5 (mg/L)
50,000–60,000
COD (mg/L)
110,000–190,000
Total solid (TS) (mg/L)
Total volatile solid (TVS) (mg/L)
80,000–120,000
Total suspended solid (TSS) (mg/L)
13,000–15,000
Total dissolved solids (TDS) (mg/L)
90,000–150,000
Chlorides (mg/L)
8000–8500
Phenols (mg/L)
8000–10,000
Sulphate (mg/L)
7500–9000
Phosphate (mg/L)
2500–2700
Total nitrogen (mg/L)
5000–7000
Zero Discharge.. A challenge..?

7. Proposed combination for Distillery spent wash treatment
BDS Reject
Sludge
Biomethanation
Distillery Effluent (DSW)
Very High COD
Acidic pH
CH4
BDS Permeate
50-60 % COD reduced
Alkaline pH
Permeate
Electrocoagulation
Reject
Sludge
Biocomposting

8. Advantages of EC Limitations of EC
Generate less quantity of sludge
Avoids the use of chemicals
Floatation for oily and grease contaminants
Less maintenance is required.
Limitations of EC
The sacrificial anodes need to be replaced periodically.
Conductivity is required in solution
Passivation on the electrodes
The cost of operating EC may be high in those areas where the cost of electricity is high.

9. Applications of EC Type of waste Type of Industry Oxygen-consuming
Breweries, Dairies, Distillers, Packaging houses, Pulp and Paper, Tanneries, Textiles
High Suspended Solids
Breweries, Coal washeries, Iron and Steel Industries, Distillers, Pulp and Paper mills, Palm oil mills
High dissolved solids
Chemical plants, Tanneries, Water softening
Oily and grease
Laundries, Metal finishing, Oil fields, Petroleum refineries, Tanneries, Palm oil mills
Coloured
Pulp and Paper mills, Tanneries, Textile dyehouses, Palm oil mills, Hospital operation theatre wastewater
High acid
Chemical plants, Coal mines, Iron and Steel, Sulfite pulp
High alkaline
Chemical plants, Laundries, Tanneries, Textile finishing mills
High Temperature
Bottle washing plants, Laundries, Power plant, Textile
Heavy Metals
Electroplating, Pulp and Paper mills, Tanneries, Textile

10. Coagulation and Electrocoagulation
A clumping of particles in water and wastewater to settle out impurities; it is often induced by coagulants such as lime, alum, and iron salts.
Electrocoagulation
The coagulant is generated by electrolytic oxidation of an appropriate anode material

11. Reactions
For Aluminum Electrodes Oxidation reaction takes place at the anode Al(s) → Al3+ (aq) + 3e- Reduction reaction takes place at the cathode 3 H2O + 3e- → (3/2) H2 + 3 OH- Overall reaction during electrolysis Al 3+→ Al (OH) n (3−n) → Al2 (OH)24+ → Al3 (OH)45+→ Al13complex→ Al (OH)3
For Iron Electrodes Oxidation reaction takes place at the anode Fe(s) → Fe(aq) e- Fe(s) → Fe(aq) e- Reduction reaction takes place at the cathode 2 H2O + 2 e- → H2(g) + 2 OH- 3H2O + 3e- → (3/2) H2 + 3 OH- Overall reaction during electrolysis Fe(aq) OH- → Fe(OH)2(s) Fe(aq)3++ 3 OH- → Fe(OH)3(s)

12. Chemical oxygen demand
Measure of oxygen equivalent of the organic matter content of the sample that is susceptible to oxidation by a strong chemical oxidant (acid + heat)
COD test results are used for monitoring and control of discharges, and for assessing treatment plant performance.
Expressed in mg/l or ppm
Potassium dichromate, a strong oxidizing agent is used under acidic conditions to find the amount of organic compound in waste water sample.
Acidity is usually achieved by the addition of sulphuric acid.
The stoichiometry of the reaction between dichromate and organic matter is:

13. COD TEST cont….
The amount of Cr3+ is determined after oxidization is complete, and is used as an indirect measure of the organic contents of the water sample
To do so, the excess potassium dichromate is titrated with ferrous ammonium sulphate (FAS) until all of the excess oxidizing agent has been reduced to Cr3+
Calculation
                                                    (A – B) ×M × 8000
                     COD as mg O2/L =       mL sample
where:
       A = mL FAS used for blank,
      B = mL FAS used for sample,
     M = molarity of FAS, and
8000 = milliequivalent weight of oxygen × 1000 mL/L.

14. Characterization of distillery spent wash after
biomethanation process (BDS)
Parameter
Before EC
After EC pH
8.2
9.3
Chemical oxygen demand (mg/L)
44000
420
Color
Dark brown
Light brown
Total dissolved solids (mg/L)
52410
100
Conductivity (mS/cm)
29.6 12
Salinity (mg/L)
22200
240

15. Conclusions
Electrocoagulation can be a suitable treatment option after Biomethanation of distillery effluent.
99% COD removal efficiency was obtained at an electrolysis time of 2 hr by Al-Al electrodes.
The COD removal efficiency obtained by electrocoagulation is much higher as compared to chemical coagulation technique.
The maximum COD of 22 % was obtained at a pH of 8.2 with a coagulant dose of 5 g/300 mL of BDS solution.

16. THANK YOU