Waste Water Cost Reduction

Waste Water Cost Reduction

The Challenge

The customer is an API manufacturer and produces approximately 2,500 t/year of mother liquors. The cost for disposal is about 200 EUR/ton. The client wants a substantial cost reduction for mother liquor disposal and does not want to depend on other companies for the treatment.

The average mother liquor composition is:

  • Water: approx. 70 %
  • Acetone: approx. 10-20 %
  • Other solvents: 10-20 %
  • Heavy compounds: approx. 1 %

Types of solvents: Methanol, DIPE, THF, Toluene Ethyl Acetate, Hexane, and Ethanol

Our Solution

  • A batch distillation plant with internal reflux column.
  • Separation of the light solvents (those more volatile than water) and the azeotropic mixtures from the water.
  • Separation of these solvents from the top of the column with a concentration of about 95-97%, leaving in the water only the salts, the heavy organic substances, and the heavy solvents.
  • Operating costs for the distillation process is negligible compared to the economic benefit of the waste disposal cost reduction.


Plant Design Data:

  • Quantity per batch: 12 m3
  • Recovered product: solvents mixture conc. 95-97%
  • Efficiency of recovery: > 98%
  • Batch duration: about 16 h
  • Quality of residual water: COD < 15,000 mg/l


Main Utilities Consumption:

  • Steam: approx. 6,000 kg/batch
  • Cooling water (from cooling tower): 40 m3/h
  • Electric power: 8 kW

The Results

Cost Savings – The Polaris technology for mother liquor treatment with Internal Reflux Distillation allowed savings on disposal costs coupled with low investment costs. Typically, Polaris plants are advantageous when the mother liquor disposal costs alone are higher than 200,000 EUR/year.

Solvent Recovery for Even Greater Savings – When the client is also interested in solvent recovery, the Polaris plant can improve production value. For this client, the annual savings (after taking into account the unit cost) was 388,500 EUR.