Stripping Column

High COD Effluent Stream Need of Stripping Column

A stripping column is a crucial component in the physical separation process used to remove one or more components from a liquid stream by converting them into a vapor stream.

In various industries, particularly the pharmaceutical and chemical sectors, effluent streams often contain a significant amount of Chemical Oxygen Demand (COD) due to the presence of different solvents used in the manufacturing processes. These solvents can be classified as low or high boiling solvents. The solvent stream, especially, is not treated in conventional Effluent Treatment Plants (ETPs) or passed through Reverse Osmosis (RO) systems. Instead, it is directly sent to a Multiple Effect Evaporator (MEE). However, feeding such effluent with a high COD directly to the MEE/Evaporator system can adversely affect the overall performance of a Zero Liquid Discharge (ZLD) system.

When heat is applied, low boiling solvents vaporize along with water vapors, occupying a significant portion of the available heat transfer area for evaporation. These low boiling solvents have lower heat transfer coefficients, thus significantly reducing the capacity of the plant. Additionally, higher COD in the feed results in contamination of condensate water, leading to issues such as high COD levels and unfavorable pH, posing significant challenges for the industry to manage such water.

To address these challenges, a STRIPPING COLUMN system is installed to remove low boiling solvents like methanol and ethanol from the effluent feed, reducing their concentration to as low as 0.5%. This ensures trouble-free operations of the MEE system.

The UNITOP stripping column effectively utilizes waste heat and can be combined with the MEE system to minimize steam consumption. Depending on the nature and characteristics of the effluent feed, different types of packing, such as random, structured, or tray types, are used in the stripping column. The stripped-out effluent is collected at the bottom of the column and then sent to the MEE for further concentration. The concentrated effluent is subsequently processed in a suitable dryer to obtain dry powder in compliance with the regulations set by the Pollution Control Board (PCB).

The stripped-out solvents are collected in a distillate tank and can be further processed as required.

Key Features of our Stripping Column:

The column is designed to handle high Total Dissolved Solids (TDS) in the feed.
Structured, random packing, or plate designs are employed based on the specific application and requirements.

Features

Column designed to handle high TDS feed.
Structured, random packing or plate design.
Is used depending on application.

Applications

Recovery of expensive solvents from effluents.
Ensuring compliance of air pollution.
Reduction of COD in effluents / recovered condensate.

Advantages

Efficient Removal of Low Boiling Solvents
Enhanced Performance of ZLD Systems
Minimized Heat Transfer Area Requirement
Reduced Contamination of Condensate Water
Flexibility in Packing Design
Waste Heat Utilization

The stripping column offers several advantages in the treatment of high COD effluent streams. Some of these advantages include

Efficient Removal of Low Boiling Solvents: The primary advantage of a stripping column is its ability to effectively remove low boiling solvents, such as methanol and ethanol, from the effluent stream. This process significantly reduces the concentration of these solvents, making the subsequent treatment processes more efficient.
Enhanced Performance of ZLD Systems: By removing low boiling solvents, the stripping column improves the overall performance of Zero Liquid Discharge (ZLD) systems. ZLD systems aim to minimize liquid waste discharge by recovering and reusing water. The stripping column ensures that high COD effluent does not directly impact the performance of downstream processes, such as Multiple Effect Evaporators (MEE), enabling more effective ZLD implementation.
Minimized Heat Transfer Area Requirement: Low boiling solvents tend to vaporize along with water vapors when heat is applied. By removing these solvents in the stripping column, the vapor stream entering the evaporator system contains fewer low boiling solvents. As a result, a smaller heat transfer area is required for evaporation, optimizing the capacity and efficiency of the plant.
Reduced Contamination of Condensate Water: High COD in the effluent feed can lead to contamination of condensate water, causing difficulties in handling and treatment. The stripping column helps mitigate this issue by removing low boiling solvents responsible for the contamination. This ensures that the condensate water collected during the evaporation process is of higher quality, with lower COD levels and improved pH characteristics.
Flexibility in Packing Design: Stripping columns can employ various types of packing, such as structured, random, or tray designs, depending on the specific application and effluent characteristics. This flexibility allows for customization and optimization of the column’s performance, ensuring efficient separation and removal of solvents.
Waste Heat Utilization: Stripping columns can effectively utilize waste heat generated from other processes, such as the MEE system. By integrating the stripping column with waste heat recovery mechanisms, the overall energy consumption and operational costs can be reduced, making the treatment process more sustainable and economically viable.

In summary, the advantages of a stripping column include efficient removal of low boiling solvents, improved performance of ZLD systems, reduced heat transfer area requirements, minimized contamination of condensate water, flexibility in packing design, and waste heat utilization. These benefits contribute to more effective and sustainable treatment of high COD effluent streams in industries.

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