In the 1990s, most of the central WWTPs in Thailand were SP and AS, with nitrogen and phosphorus removal introduced to the WWTPs in Bangkok from 2000 (JICA; TEC and NK company 2011). These pipe collection systems are combined sewer pipe systems. The central WWTPs usually comprise two steps: primary treatment and secondary treatment. Primary treatment consists of coarse and fine sieves, a sand trap, a grease trap and a preliminary sedimentation tank to separate large solids, while secondary treatment consists of a biological reactor to remove suspended solids and organic matter from wastewater. In 2017, there were 101 constructed sites of central WWTPs, comprising 12% with a capacity exceeding 50,000 m3/day (large systems), 45% with a capacity of 10,000–50,000 m3/day (medium-sized systems), and the rest with a capacity below 10,000 m3/day (small systems). Table 4 presents the details of 97 completed and operational central WWTPs (out of a total of 101 construction projects) and 7 cluster wastewater systems spread across the country (Office of the Environment Region 1-16 2016; Pollution Control Department 2017b; Office of Strategy and Evaluation 2020). The total treatment capacity of WWTPs is only 2.64 mil.m3/day, accounting for 26.6% of the total wastewater volume of 9.93 mil.m3/day (Pollution Control Department 2021). The most frequently installed type of WWTP is a stabilization pond (SP), accounting for 42%, followed by oxidation ditch (OD) (21%), aerated lagoon (AL) (18%) and AS (16%), including sequencing batch reactor (SBR) and membrane sequencing batch reactor (MSBR). Some treatment plants use more than one type, such as CW + SP and AS + SP.
Number and treatment capacity of municipal and industrial estate WWTPs in Thailand, along with wastewater reuse activity
| Region . | Province name and no. of municipalitiese . | River basin . | Municipal WWTP . | Industrial estate WWTP . | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Type . | No. . | Treatment capacity (m3/day) . | Actual treatment (%) . | Treated wastewater reuse activity . | Type . | No. . | Treatment capacity (m3/day) . | Actual treatment (%) . | Treated wastewater reuse activity . | |||
| North | Chiang Mai (5) | Ping | AL + Sed.P + OD | 1 | 55,000 | 18 | A | |||||
| Chiang Rai (1) | North Khong | AL + Sed.P + Chlor.P | 1 | 27,200 | 37 | |||||||
| Kamphaeng Phet (3) | Yom | SP + Chlor.P | 2 | 14,000 | 23 | |||||||
| Lampang (4) | Yom | SP + CW | 1 | 12,300 | 33 | A, E | ||||||
| Lamphun (1) | Ping | AS(SBR) +UV | 1 | 10,000 | 100 | G1 | SP + AL | 1 | 24,000 | 61 | G1, C2, C4, CT | |
| AS | 1 | 2,000 | 106 | |||||||||
| Nakhon Sawan (3) | Chao Phraya | SP | 1 | 1,650 | 51 | G1 | ||||||
| AS (MSBR) + Chlor.P | 1 | 36,000 | 100 | G1 | ||||||||
| Nan (1) | Nan | SP + Chlor.P | 1 | 8,259 | 67 | |||||||
| Phayao (2) | Yom | SP | 1 | 9,700 | 49 | A | ||||||
| Phichit (3) | Nan | AL + Maturation Pond | 1 | 12,000 | 42 | SP | 1 | 5,100 | 4 | G1 | ||
| SP | 1 | 7,164 | 14 | |||||||||
| Phitsanulok (2) | Nan | SP | 1 | 25,000 | ||||||||
| Septic and Aerationf Filter Tank | 2 | 320 | ||||||||||
| Sukhothai (3) | Yom | SP | 1 | 8,400 | 83 | A | ||||||
| Tak (2) | Ping, Salawin | SP + Chlor.P | 2 | 16,400 | 37 | |||||||
| Northeast | Amnat Charoen (1) | Mun | SP | 1 | 12,819 | 46 | A, G2 | |||||
| Buriram (3) | Mun | AL + Chlor.P | 1 | 13,000 | 62 | A, G2 | ||||||
| Chaiyaphum (1) | Mun | AL | 1 | 5,000 | ||||||||
| Kalasin (2) | Chi | AL + Chlor.P | 1 | 14,000 | 3 | A | ||||||
| Khon Kaen (7) | Chi | AL + Chlor.P | 1 | 78,000 | 51 | G1, S, C1, C2 | ||||||
| CWf | 1 | 400 | 63 | G1 | ||||||||
| Maha Sarakham (1) | Chi | SP + Chlor.P | 1 | 4,200 | 81 | G1 | ||||||
| SP + CW | 1 | 1,500 | 50 | |||||||||
| Mukdahan (1) | Northeast Khong | SP | 1 | 8,500 | 36 | A, G2 | ||||||
| Nakhon Ratchasima (5) | Mun | SP + AS | 1 | 70,000 | 71 | 1 | 4,000 | 56 | G1, C2, C4, P1 | |||
| SP | 2 | 15,000 | 56 | G1 | ||||||||
| Sakon Nakhon (1) | Northeast Khong | SP + wetland | 2 | 18,054 | 72 | |||||||
| Surin (1) | Mun | SP | 1 | 13,600 | 81 | A, L | ||||||
| CW | 1 | 360 | 56 | |||||||||
| Ubon Ratchathani (5) | Mun | AL | 1 | 22,000 | ||||||||
| SP | 1 | 18,000 | 17 | A, F | ||||||||
| Udon Thani (4) | Northeast Khong | SP + Chlor.P | 1 | 43,902 | 34 | AS | 1 | 6,400 | 87 | G1 (buffer zone), C2, C4 | ||
| Yasothon (1) | Chi | SP | 1 | 7,246 | 38 | A, F | ||||||
| East | Chachoengsao (1) | Bang Pakong | OD + Chlor.P | 1 | 12,000 | 58 | AS | 3 | 20,600 | G1, CT | ||
| SP + CW + Chlor.P | 1 | 5,000 | 40 | AL | 1 | 7,200 | ||||||
| SBR | 1 | 8,400 | ||||||||||
| Chanthaburi (5) | East Coast Gulf | SP | 2 | 21,500 | 35 | |||||||
| Chonburi (12) | Bang Pakong, East Coast Gulf | OD | 3 | 41,000 | 66 | G1, C3 | AS, AS + AL | 8 | 55,650 | G1, C2, C4, P2, P3 (UF + RO (3 plants)) | ||
| SP | 1 | 5,380 | 44 | AL, SP + AL | 5 | 29,950 | ||||||
| AS (SBR) + Chlor.P | 3 | 110,500 | 95 | SBR | 2 | 85,000 | ||||||
| AL | 2 | 12,900 | 35 | |||||||||
| Prachinburi (1) | Bang Pakong | Anaerobic pond + AL | 1 | 4,500 | G1, C2, C4, P3 (UF (1 plant)) | |||||||
| AS-SBR | 1 | 5,280 | ||||||||||
| Rayong (3) | East Coast Gulf | AL + Chlor.P | 2 | 16,000 | 9 | AS | 5 | 77,820 | G1, C2, C4, P2, P3 (UF + RO (1 plant) and MF (1 plant)) | |||
| OD + Chlor.P | 1 | 8,000 | 11.5 | SBR, SBR + CW, SBR + BAF | 3 | 63,200 | ||||||
| ASf | 2 | 1,300 | 91 | AL | 4 | 41,000 | ||||||
| Sa Kaeo (3) | Biological treatment | 1 | 2,100 | |||||||||
| South | Krabi (1) | Peninsula-W/Ea | AS + CW | 1 | 400 | 150 | ||||||
| AL | 1 | 12,000 | 51 | A | ||||||||
| Nakhon Si Thammarat (4) | Peninsula-U/Eb | SP | 1 | 33,000 | 30 | |||||||
| Peninsula-W/Ea | RBC | 1 | 10,000 | 50 | G1, C3 | |||||||
| Phuket (3) | Peninsula-W/Ea | OD + Chlor.P | 3 | 65,350 | 78 | Tap water by RO | ||||||
| AS + Chlor.P | 3 | 10,560 | ||||||||||
| Songkhla (13) | Thale Sap Songkla | SP + CW | 1 | 138,000 | 27 | G1 | AS | 3 | 18,700 | G1, C2, C4 | ||
| AL + Chlor.P | 1 | 35,000 | 71 | A | ||||||||
| Surat Thani (5) | Peninsula-U/Eb | CW | 1 | 200 | 30 | |||||||
| OD | 3 | 17,050 | ||||||||||
| Trang (2) | Peninsula-W/Ea | AL | 1 | 17,700 | 57 | |||||||
| Yala (3) | Peninsula-L/Ec | SP | 1 | 3,200 | ||||||||
| AL | 1 | 4,600 | ||||||||||
| Center | Ang Thong (1) | Chao Phraya | AL | 1 | 8,200 | 31 | A | AS | 1 | 6,610 | G1, C2, C4, P3 (UF + RO (1 plant) | |
| Ayutthaya (6) | Chao Phraya | OD + AL | 1 | 24,000 | 42 | A (rice field) | AS | 3 | 42,800 | G1, C2, C4 | ||
| Bangkok (capital) | Chao Phraya | AS | 8 | 1,112,000 | AS | 2 | 22,300 | |||||
| Chai Nat (1) | Tha Chin | AL + SP | 1 | 5,870 | 61 | A (rice field) | ||||||
| Kanchanaburi (3) | Mae Klong | OD | 1 | 24,000 | ||||||||
| Lopburi (3) | Pasak | SP + Chlor.P | 1 | 1,000 | ||||||||
| Nakhon Pathom (6) | Tha Chin | SP | 1 | 25,000 | 33 | |||||||
| Nonthaburi (9) | Chao Phraya | OD + Chlor.P | 1 | 38,500 | 34 | |||||||
| Pathum Thani (10) | Chao Phraya | AL | 1 | 11,000 | 11 | |||||||
| Phetchaburi (2) | Phetcha-Prachuapd | SP | 1 | 10,000 | 47 | E (mangrove forest) | ||||||
| AL | 1 | 17,000 | 29 | G1 | ||||||||
| Prachuap Khiri Khan (2) | Phetcha-Prachuapd | AL + SP | 1 | 8,000 | 79 | |||||||
| RBC + Chlor.P | 1 | 8,000 | 100 | G3 | ||||||||
| OD + Chlor.P | 1 | 17,000 | 71 | |||||||||
| Ratchaburi (4) | Mae Klong | SP | 2 | 25,000 | 47 | A (rice, lotus), L | AS | 1 | 32,000 | G1, C2, C4, CT | ||
| OD + Chlor.P | 1 | 5,000 | 64 | |||||||||
| Saraburi (4) | Pasak | OD | 1 | 24,000 | AS | 2 | 13,200 | |||||
| Sing Buri (2) | Chao Phraya | SP | 1 | 4,500 | 33 | |||||||
| Suphan Buri (2) | Tha Chin | SP | 1 | 12,500 | 74 | |||||||
| Samut Prakarn (7) | Chao Phraya | AS | 4 | 69,400 | 62 | |||||||
| RBC | 1 | 2,300 | ||||||||||
| Samut Sakorn (4) | Tha Chin | AS prefabricatedf Tank | 2 | 160 | 100 | AS | 2 | 24,000 | G1, C2, C4, P3 (AC + UF (1 plants)) | |||
| UASB + SBR | 1 | 1,500 | ||||||||||
| Region . | Province name and no. of municipalitiese . | River basin . | Municipal WWTP . | Industrial estate WWTP . | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Type . | No. . | Treatment capacity (m3/day) . | Actual treatment (%) . | Treated wastewater reuse activity . | Type . | No. . | Treatment capacity (m3/day) . | Actual treatment (%) . | Treated wastewater reuse activity . | |||
| North | Chiang Mai (5) | Ping | AL + Sed.P + OD | 1 | 55,000 | 18 | A | |||||
| Chiang Rai (1) | North Khong | AL + Sed.P + Chlor.P | 1 | 27,200 | 37 | |||||||
| Kamphaeng Phet (3) | Yom | SP + Chlor.P | 2 | 14,000 | 23 | |||||||
| Lampang (4) | Yom | SP + CW | 1 | 12,300 | 33 | A, E | ||||||
| Lamphun (1) | Ping | AS(SBR) +UV | 1 | 10,000 | 100 | G1 | SP + AL | 1 | 24,000 | 61 | G1, C2, C4, CT | |
| AS | 1 | 2,000 | 106 | |||||||||
| Nakhon Sawan (3) | Chao Phraya | SP | 1 | 1,650 | 51 | G1 | ||||||
| AS (MSBR) + Chlor.P | 1 | 36,000 | 100 | G1 | ||||||||
| Nan (1) | Nan | SP + Chlor.P | 1 | 8,259 | 67 | |||||||
| Phayao (2) | Yom | SP | 1 | 9,700 | 49 | A | ||||||
| Phichit (3) | Nan | AL + Maturation Pond | 1 | 12,000 | 42 | SP | 1 | 5,100 | 4 | G1 | ||
| SP | 1 | 7,164 | 14 | |||||||||
| Phitsanulok (2) | Nan | SP | 1 | 25,000 | ||||||||
| Septic and Aerationf Filter Tank | 2 | 320 | ||||||||||
| Sukhothai (3) | Yom | SP | 1 | 8,400 | 83 | A | ||||||
| Tak (2) | Ping, Salawin | SP + Chlor.P | 2 | 16,400 | 37 | |||||||
| Northeast | Amnat Charoen (1) | Mun | SP | 1 | 12,819 | 46 | A, G2 | |||||
| Buriram (3) | Mun | AL + Chlor.P | 1 | 13,000 | 62 | A, G2 | ||||||
| Chaiyaphum (1) | Mun | AL | 1 | 5,000 | ||||||||
| Kalasin (2) | Chi | AL + Chlor.P | 1 | 14,000 | 3 | A | ||||||
| Khon Kaen (7) | Chi | AL + Chlor.P | 1 | 78,000 | 51 | G1, S, C1, C2 | ||||||
| CWf | 1 | 400 | 63 | G1 | ||||||||
| Maha Sarakham (1) | Chi | SP + Chlor.P | 1 | 4,200 | 81 | G1 | ||||||
| SP + CW | 1 | 1,500 | 50 | |||||||||
| Mukdahan (1) | Northeast Khong | SP | 1 | 8,500 | 36 | A, G2 | ||||||
| Nakhon Ratchasima (5) | Mun | SP + AS | 1 | 70,000 | 71 | 1 | 4,000 | 56 | G1, C2, C4, P1 | |||
| SP | 2 | 15,000 | 56 | G1 | ||||||||
| Sakon Nakhon (1) | Northeast Khong | SP + wetland | 2 | 18,054 | 72 | |||||||
| Surin (1) | Mun | SP | 1 | 13,600 | 81 | A, L | ||||||
| CW | 1 | 360 | 56 | |||||||||
| Ubon Ratchathani (5) | Mun | AL | 1 | 22,000 | ||||||||
| SP | 1 | 18,000 | 17 | A, F | ||||||||
| Udon Thani (4) | Northeast Khong | SP + Chlor.P | 1 | 43,902 | 34 | AS | 1 | 6,400 | 87 | G1 (buffer zone), C2, C4 | ||
| Yasothon (1) | Chi | SP | 1 | 7,246 | 38 | A, F | ||||||
| East | Chachoengsao (1) | Bang Pakong | OD + Chlor.P | 1 | 12,000 | 58 | AS | 3 | 20,600 | G1, CT | ||
| SP + CW + Chlor.P | 1 | 5,000 | 40 | AL | 1 | 7,200 | ||||||
| SBR | 1 | 8,400 | ||||||||||
| Chanthaburi (5) | East Coast Gulf | SP | 2 | 21,500 | 35 | |||||||
| Chonburi (12) | Bang Pakong, East Coast Gulf | OD | 3 | 41,000 | 66 | G1, C3 | AS, AS + AL | 8 | 55,650 | G1, C2, C4, P2, P3 (UF + RO (3 plants)) | ||
| SP | 1 | 5,380 | 44 | AL, SP + AL | 5 | 29,950 | ||||||
| AS (SBR) + Chlor.P | 3 | 110,500 | 95 | SBR | 2 | 85,000 | ||||||
| AL | 2 | 12,900 | 35 | |||||||||
| Prachinburi (1) | Bang Pakong | Anaerobic pond + AL | 1 | 4,500 | G1, C2, C4, P3 (UF (1 plant)) | |||||||
| AS-SBR | 1 | 5,280 | ||||||||||
| Rayong (3) | East Coast Gulf | AL + Chlor.P | 2 | 16,000 | 9 | AS | 5 | 77,820 | G1, C2, C4, P2, P3 (UF + RO (1 plant) and MF (1 plant)) | |||
| OD + Chlor.P | 1 | 8,000 | 11.5 | SBR, SBR + CW, SBR + BAF | 3 | 63,200 | ||||||
| ASf | 2 | 1,300 | 91 | AL | 4 | 41,000 | ||||||
| Sa Kaeo (3) | Biological treatment | 1 | 2,100 | |||||||||
| South | Krabi (1) | Peninsula-W/Ea | AS + CW | 1 | 400 | 150 | ||||||
| AL | 1 | 12,000 | 51 | A | ||||||||
| Nakhon Si Thammarat (4) | Peninsula-U/Eb | SP | 1 | 33,000 | 30 | |||||||
| Peninsula-W/Ea | RBC | 1 | 10,000 | 50 | G1, C3 | |||||||
| Phuket (3) | Peninsula-W/Ea | OD + Chlor.P | 3 | 65,350 | 78 | Tap water by RO | ||||||
| AS + Chlor.P | 3 | 10,560 | ||||||||||
| Songkhla (13) | Thale Sap Songkla | SP + CW | 1 | 138,000 | 27 | G1 | AS | 3 | 18,700 | G1, C2, C4 | ||
| AL + Chlor.P | 1 | 35,000 | 71 | A | ||||||||
| Surat Thani (5) | Peninsula-U/Eb | CW | 1 | 200 | 30 | |||||||
| OD | 3 | 17,050 | ||||||||||
| Trang (2) | Peninsula-W/Ea | AL | 1 | 17,700 | 57 | |||||||
| Yala (3) | Peninsula-L/Ec | SP | 1 | 3,200 | ||||||||
| AL | 1 | 4,600 | ||||||||||
| Center | Ang Thong (1) | Chao Phraya | AL | 1 | 8,200 | 31 | A | AS | 1 | 6,610 | G1, C2, C4, P3 (UF + RO (1 plant) | |
| Ayutthaya (6) | Chao Phraya | OD + AL | 1 | 24,000 | 42 | A (rice field) | AS | 3 | 42,800 | G1, C2, C4 | ||
| Bangkok (capital) | Chao Phraya | AS | 8 | 1,112,000 | AS | 2 | 22,300 | |||||
| Chai Nat (1) | Tha Chin | AL + SP | 1 | 5,870 | 61 | A (rice field) | ||||||
| Kanchanaburi (3) | Mae Klong | OD | 1 | 24,000 | ||||||||
| Lopburi (3) | Pasak | SP + Chlor.P | 1 | 1,000 | ||||||||
| Nakhon Pathom (6) | Tha Chin | SP | 1 | 25,000 | 33 | |||||||
| Nonthaburi (9) | Chao Phraya | OD + Chlor.P | 1 | 38,500 | 34 | |||||||
| Pathum Thani (10) | Chao Phraya | AL | 1 | 11,000 | 11 | |||||||
| Phetchaburi (2) | Phetcha-Prachuapd | SP | 1 | 10,000 | 47 | E (mangrove forest) | ||||||
| AL | 1 | 17,000 | 29 | G1 | ||||||||
| Prachuap Khiri Khan (2) | Phetcha-Prachuapd | AL + SP | 1 | 8,000 | 79 | |||||||
| RBC + Chlor.P | 1 | 8,000 | 100 | G3 | ||||||||
| OD + Chlor.P | 1 | 17,000 | 71 | |||||||||
| Ratchaburi (4) | Mae Klong | SP | 2 | 25,000 | 47 | A (rice, lotus), L | AS | 1 | 32,000 | G1, C2, C4, CT | ||
| OD + Chlor.P | 1 | 5,000 | 64 | |||||||||
| Saraburi (4) | Pasak | OD | 1 | 24,000 | AS | 2 | 13,200 | |||||
| Sing Buri (2) | Chao Phraya | SP | 1 | 4,500 | 33 | |||||||
| Suphan Buri (2) | Tha Chin | SP | 1 | 12,500 | 74 | |||||||
| Samut Prakarn (7) | Chao Phraya | AS | 4 | 69,400 | 62 | |||||||
| RBC | 1 | 2,300 | ||||||||||
| Samut Sakorn (4) | Tha Chin | AS prefabricatedf Tank | 2 | 160 | 100 | AS | 2 | 24,000 | G1, C2, C4, P3 (AC + UF (1 plants)) | |||
| UASB + SBR | 1 | 1,500 | ||||||||||
AC, Activated carbon; AL, Aerated lagoon; AS, Activated sludge; BAF, Biological aerated filtration; Chlor.P, Chlorine contact pond; CW, Constructed wetland; MSBR, Membrane sequencing batch reactor; OD, Oxidation ditch; RBC, Rotating biological contactor; SBR, Sequencing batch reactor; Sed.P, Sedimentation pond; SP, Stabilization pond.
A, Agricultural irrigation; C1, Cleaning public water pipes; C2, Cleaning roads; C3, Washing garbage trucks; C4, Cleaning equipment; CT, Factory construction; E, Ecological preservation; F, Fishery; G1, Green space irrigation; G2, Gardening irrigation; G3, Watering golf courses; L, Livestock uses; P1, Second-grade water for factories; P2, Cooling water for factories; P3, Raw water for industrial water production; S, Seedling cultivation.
aPeninsula-West/East Coast.
bPeninsula-Upper East Coast.
cPeninsula-Lower East Coast.
dPhetchaburi-Prachuap Khiri Khan.
ePopulation density > 3,000 people/km2 (Department of Local Administration 2020).
fCluster wastewater system.