ZLD Solutions – Ethanol Plants

Uttamenergy provides ZLD solutions (Zero liquid discharge) for molasses-based distilleries or ethanol facilities that preserve resources and safeguard the environment by accumulating water and renewable energy.

Typically, distilleries’ effluent, such as wasted wash/slop/vinasse, is proportional to 9 to 12 times daily ethanol output, with a solid percentage of 11 to 14%. The following is an example of an effluent analysis:

● Colour as deep reddish brown
● Aromatic odour
● Specific gravity as 1.05
● pH as 4.5
● BOD as 50000-55000
● COD as 80000-85000
● Total nitrogen as 927 mg/l
● Total phosphate as 45.6 mg/l
● Total potassium as 61.0 mg/l

ZLD solutions can be generated by bio methanation or incineration. Please refer to the schemes demonstrated below.

Bio Methanation Route

Effluent vinasse/slop from the distillery is treated to bio methanation in a bio digestor, which significantly decreases the BOD/COD content by creating biogas with a concentration of 50-55% on a volume basis. This biogas can be used in one of three ways, all of which are completely reliant on market economics.

Option-1              : Use as an auxiliary fuel in the boiler.
Option-2              : Generate electricity using gas engines after purifying biogas to the necessary standard.

Option-3              : Refill CNG canisters by purifying biogas with a methane level of more than 95%.

To recover water, the digestate from the bio methanation process is concentrated in a multiple-effect evaporator. To yield manure, the concentrate will be further transferred to either bio-composting or a dryer.

Incineration Route

The distillery’s vinasse/slop effluent is concentrated to 52-60% solids in a multiple-effect evaporator before being directly incinerated in the combustion chamber above the grate in the incineration boiler. Supplementary fuel, such as bagasse, wood chips, rice husk, or coal, is always necessary for optimal and sustainable combustion. For fuel flexibility, combustors with travelling grate stokers are preferable.