Thailand Thailand sets an effluent standard for desalination plant

Thailand sets an effluent standard for desalination plant

Thailand announced “Notification of the Ministry of Industry Prescribing Standards for Controlling the Discharge of Wastewater Effluent from Factory Operating Business on Desalination B.E. 2564 (2021)” in the Royal Gazette on 16 March 2022. The notification sets out an effluent standard for desalination plants under the Factory Act, B.E. 2535 (1992). Prior to the announcement, the Ministry of Natural Resources and Environment has already published an effluent standard for desalination plants in November 2017. The notification from the Ministry of Industry, which is in line with the one from the Ministry of Natural Resources and Environment (2017), has been effective from the next day of the publication in the Royal Gazette.

Target business

The notification applies to a factory that operates a desalination business classified in No. 90 in the Appendix to the Ministerial Regulation issued pursuant to Section 7 of the Factory Act B.E. 2535, as amended by Factory Act (No. 2) B.E. 2562, and that uses seawater as a raw material in the manufacturing process and discharges wastewater effluent to the sea.


The effluent standard is set as follows;

Parameter Standard for desalination plant
pH 6.0 – 8.5
Free Chlorine 0.1 mg/L
Toal Kjeldahl Nitrogen(TKN) 10 mg/L
Settleable solids 2 ml/L
Turbidity 100 NTU

The point of wastewater discharge shall have adequate seawater circulation. To avoid environmental impacts, wastewater effluent shall be discharged via an outfall using one of the following methods:

  • Prior to discharge, seawater must be pumped to mix with wastewater at a dilution ratio of at least 20 parts seawater to 1 part wastewater;
  • Prior to discharge, seawater for cooling shall be mixed with wastewater;
  • In the event of other methods besides those defined above, multiport diffusers shall be used at the tip of the drainpipe; or
  • Other methods as approved by the Department of Industrial Works.


Download the original text of the Notification at

Author / Responsibility


Managing Director, Green & Blue Planet Solutions Co., Ltd.

Business Performance

Managing and leadding a variey of environmental projects in Thailand and SE Asia


MSc in Envionmental Engineering and Management, Asian Institute of Technology (Thailand),
MSc in Environmental Science, UNESCO-IHE Institute for Water Education (the Netherlands)