Chiang Mai University (CMU) has water quality standards and guidelines for water discharges, to uphold water quality and protect ecosystems, wildlife and human health, in support of Sustainable Development Goal 15 (Life on Land). The University's target is that treated wastewater leaving CMU must be cleaner than law requires. This has been in force since the CMU Annoucement on Measures for Wastewater Discharge from University Units, issued on 22 August 2017 under the Enhancement and Conservation of National Environment Quality Act B.E.2535(1992).
What the University must do. CMU treats all wastewater from its campuses before it is released to public water. It keeps daily operating records for its treatment plants and submits a monthly summary report, including effluent test results, to the locol authority by the 15th of each following month, as required by the Ministerial Regulation of 2012 under the Enhancement and Conservation of National Environmental Quality Act.
What ever faculty and unit must do. Each unit that connects to the central sewer must :
- Buildings, dormitories and shop: install screen that remove solid waste water before water enters the sewer.
- Laboratories using chemicals: install a neutralisation tank that keeps wastewater at pH 6.5-7.5 before it enters the sewer, and keep toxic chemicals that could kill the treatment plan's microorganisms in separate holding tanks for proper disposal. Discharging these chemicals into the sewer is strictly forbidden.
- Canteens, restaurants and markets: separate food scraps fromwastewater, install grease traps at every washing point, and empty them every time wastewater is discharged.
- Construction: never build over the central sewer, and consult the Wastewater Treatment Unit before any new project so it does not harm the sewer, the landscape or the environment.
- Maintenance and reporting: keep internal drains in good repair and report water use for every activity by the 3rd of each month.
How wastewater is treated. CMU runs three conventional activeted sludge treatment plants, 24 hours a day:
Plant
| Capacity ( Cubic metre per day) |
Plant1, Suan Dok
| 10,000
|
Plant2, Mae Hia
| 1,750
|
Plant3, Choeng Doi
| 10,000
|
The Wasrewater Treatment Unit has three teams: machinery operators who run the plants, a field team that maintains the sewer network, and a laboratory team that tests water quality and shares knowledge with students, schools and public or private organisations.
Monitoring result in 2025. Treated water from Plant1 (Suan Dok) is tested every month against the Ministry of Natural Resources and Environment's building effluent standard of 28 June 2024 for Type A buildings (higher education institutions with 25,000 cubic metre or more of floor space). From January to December 2025, every result met the standard:
Parameter
| Legal limit
| CMU results, Jan-Dec 2025
|
pH
| 5.5-9.0
| 6.17-7.15
|
BOD
| less than equal to 20 mg/l
| 1.79-5.57 mg/l
|
Total suspended solids
| less than equal to 30 mg/l
| 3.40-6.71 mg/l
|
Fat, oil and grease
| less than equal to 20 mg/l
| 0.44-1.16 mg/l
|
Total Kjeldahi nitrogen
| less than equal to 35 mg/l
| 4.85-8.67 mg/l
|
Total dissolved solids
| less than equal to 1,000 mg/l
| 238-361 mg/l
|
Free chlorine
| less than equal to 1.0 mg/l
| 0.04-0.28 mg/l
|
Sulfide
| less than equal to 1.0 mg/l
| 0.01-0.08 mg/l
|
Total coliform bacteria
| less than equal to 5,000 MPN/100 ml
| 1.1-8.4 MPN/100 ml
|
Fecal coliform bacteria
| less than equal to 1,000 MPN/100 ml
| 1.18-8.4 MPN/100 ml |
BOD, a key measure of organic pollution, stayed at or below 28% of the legal limit in every month.
Sources
- Chiang Mai University. Announcement: Measures for Wastewater Discharge from University Uniys, 22 August 2017.
- CMU Green Office. "Water quality analysis of Wastewater Treatment Plant1(Suan Dok), January-December 2025".
- CMU Green Office.Attachment 4.2, "Wastewater management".