Assessment report



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Treatment Process

  1. Influent to WWTP:


The influents to WWTPs are in two following types:

  • Domestic influent collected in separated sewers networks: at 3 cities (Da Lat, Buon Me Thuot, Binh Duong) and Phu My Hung Urban Area (HCMC);

  • Domestic influent mixed with rainwater in the combined sewers networks or partially separated networks: in remaining 10 cities.

Table 7.2 - Length of wastewater sewers to WWTPs




Combined or Semi Separated Networks

Separated Networks

Name of Utilities

Combined sewers

Interceptor

CSOs

Storm Drains

Sewers

Unit

Km

Km

Quantity

Km

Km

Ha Long URENCO JSC

20

20

68







Bac Giang UDPC

55.00

28

9







Ha Noi HSDC

20.60

1.30

0







Bac Ninh DWT Co, Ltd

130

5

18







Hai Duong UWM JSC

224.13

8.81

45.00







Quang Binh EUD Co, Ltd

62.61

4.10

12.00







 Da Nang SDC

943.00

45.16

158.00







Dak Lak UMENCO










97.60

64.80

LAWACO













85.00

HCMC UDC

N/I

N/I

N/I

N/I

N/I

Phu My Hung Corp










93.90

55.00

BIWASE













180.00

Soc Trang UWC

117.70

10.70

16.00






      1. Technical requirements for effluent


  1. Regarding requirements for effluent quality, one of two following national technical regulations (QCVN) has been applied for each WWT plant:

  • QCVN 14:2008/BTNMT- National Technical Regulation on Domestic effluent (hereafter referred to as QCVN 14); and

  • QCVN 40:2011/BTNMT- National Technical Standards on Industrial effluent (hereafter referred to as QCVN 40).

Details of application of these QCVNs are summarized in Table 7.3, specifically:

  • 4 utilities applied QCVN 40: Hanoi, HCMC (applied both QCVN 14 and QCVN 40) and Binh Duong;

  • 8 remaining utilities and HCMC applied QCVN 14: Ha Long, Bac Giang, Bac Ninh, Hai Duong, Dak Lak, Lam Dong, HCMC;

  • 1 utility applied TCVN 7222 - 2002 standard: Quang Binh

  1. Technical requirements on effluent quality:

  • There is only one utility (Binh Duong WWTP) which applied Column A (discharged into the water source using for water supply) of QCVN 40

  • 12 remaining utilities with quality have applied column B (discharged into the water source not using for water supply) of QCVN 40 or QCVN 14

Table 7.3 - Technical requirements of effluent quality

Utilities

QCVN 14

QCVN 40

TCVN 7222-2002




Column A

Column B

Column A

Column B




A, Northern Midland and Mountainous Region
















Ha Long URENCO JSC

 



 

 




Bac Giang UDPC

 



 

 




B, Red River Delta Region

 

 

 

 




Ha Noi HSDC















Bac Ninh DWT Co, Ltd

 



 

 




Hai Duong UWM JSC

 



 

 




C, Central Coast Region

 

 

 

 




Quang Binh EUD Co, Ltd

 




 

 

Column 2 (after Primary treatment )

 Da Nang SDC

 




 






D, Central Highland Region

 

 

 

 




Dak Lak UMENCO

 



 

 




LAWACO

 



 

 




E, South East Region

 

 

 

 




HCMC UDC

 



 






Phu My Hung Corp

 












BIWASE









 




F, Mekong River Delta Region
















Soc Trang UWC















  1. Compare the value C (pollution parameters as the basis for calculation of maximum allowance values in the effluent) of QCVN 14 and QCVN 40 standards.

  • Parameters with same value C including five (5) factors:

  • pH (lower requirements in QCVN 14);

  • BOD5 (20oC);

  • TSS;

  • Ammonium (as N);

  • Total Coliforms.

  • Three (3) parameters stipulated in QCVN 14 but not specified in QCVN 40:

  • Total dissolved solids (TDS);

  • Animal fat and vegetable oil;

  • Total surface active agents.

  • Otherwise, the following parameters are stipulated in QCVN 40 but not included QCVN 14:

  • Temperature;

  • Color;

  • COD;

  • Heavy metals: arsenic, mercury, lead, Cadmium, Chromium (VI), chromium (III), Copper, Zinc, Nickel, Manganese, Iron;

  • Total cyanide;

  • Total phenol;

  • Mineral fats and oils;

  • Fluoride;

  • Total phosphorus (as P);

  • Chloride (not applicable when discharging into saline and brackish water);

  • Residual chlorine;

  • Total organic chlorine pesticides;

  • Total organic phosphorus pesticides;

  • Total PCB;

  • Gross α radioactivity;

  • Gross β radioactivity.

By comparison it found that number of parameters controlled under QCVN 40 is more than that of under QCVN 14. As results, following recommendation was made.


      1. Recommendation C2:


In principle, a QCVN on urban wastewater is not yet specified. It is necessary to:

  • Issue a specific QCVN for urban wastewater or;

  • Supplement a specific regulation: where there is only domestic effluent without industrial effluent, it may be applied QCVN 14, but in case of having both domestic and industrial effluent, it should apply QCVN 40. In fact in some urban areas, beside domestic wastewater, it may mixed with industrial effluent (for example Binh Hung Hoa station in HCMC announced as 40% of rainwater; 40% of domestic and 20% for industrial effluent).
      1. Treatment Process


Treatment processes of WWTPs are shown in the Table 7. 4. Design Parameters and Treatment Processes.

In Vietnam, WWTPs for urban areas have just operated in recent 10 years. The WWTPs are being constructed under ODA projects with technology design and equipment provided by various companies in the world. The number of WWTPs not yet many but applied many types of technology treatment process, including:



  1. Mechanical treatment.

  2. Biological treatment.

  • Biological lagoons/ stabilization ponds:

  • Anaerobic pond;

  • Aerobic, facultative pond;

  • Maturation pond.

  • Trickling filter (TF).

  • Activated sludge:

  • CAS (Conventional Activated Sludge);

  • AAO (Aerobic – Anaerobic - Oxidation);

  • OD (oxidation ditch (circulate));

  • SBR, ASBR (Sequencing Batch Reactor).
      1. Recommendation C3:


Many projects on construction of WWTPs would certainly be carried out in the coming years. The Ministry of Construction should evaluate effectiveness in term of economic and technical then provide guidance on selection of treatment processes that appropriate with the conditions in Vietnam.

Table 7.4 - Treatment Process



Province

Utility

WWTP

Capacity

(m3/day)

Type of sewers

Technology

Treatment Process provided by Utility

Quality of effluent

Col, A

Col, B

Quang Ninh

Ha Long URENCO JSC

2 stations: Ha Khanh and Bai Chay

10,500

CSS

SBR

Screen > Grit chamber > Anaerobic > Primary clarifier > Aeration tank > Secondary clarifier > Disinfection > Discharge into sea






Bac Giang

Bac Giang UDP Center

Bac Giang

10,000

CSS

OD

Screen > Grit chamber > Mixing Tank > Biological treatment > Clarifier > Disinfection






Ha Noi

Ha Noi HSDC

2 stations Kim Lien and Truc Bach

10,200

CSS

AAO

Screen> Grit chamber > Primary settling tank > Anaerobic tank > Anoxic tank> Aerobic tank > secondary settling tank > Disinfection






Bac Ninh

Bac Ninh DWT Ltd.

Bac Ninh

17,500

CSS

SBR

Screen > Grit chamber > Mixing Tank > C-Tech Tank (biological treatment) > Retention pond






Hai Duong

Hai Duong UWM JSC

Hai Duong

13,000

CSS

SBR

Screen > Grit chamber > Primary clarifier tank > Sludge tank > Sludge decomposition > Ngoc Chau channel






Quang Binh

Quang Binh EUD Ltd.

Dong Hoi

8,570

CSS

OD

Screen > Grit chamber > aerobic pond > Facultative pond >Maturation Pond >Constructed wetland




TCVN 7222-2002 column2

Da Nang

 Da Nang SDC

4 stations Son Tra, Hoa Cuong, Phu Loc, Ngu Hanh Son

100,370

CSS

Anaerobic pond

Screen > Flow channel> Anaerobic ponds






Đăk Lắc

DakLak UMENCO

Buon Ma Thuot

8,125

SSS

Stabilization pond

Screen > Grit chamber> Flow chamber > Anaerobic ponds A1-A2 > Cascade aerator CA1 > Facultative ponds F1-1,F2-1 > Cascade aerator  CA2 > Maturation ponds M2-1;M2-2 and M1-1,M1-2






Lam Dong

LAWACO

Da Lat

7,400

SSS

TF

Screen > Grit chamber> Imhoff tank > Trickling filter > Secondary clarifier tank> Maturation pond






HCMC

HCMC UDC

Binh Hung

141,000

CSS

CAS

Primary clarifier tank> Aeration tank>

Secondary clarifier tank > Disinfection;

Gravity sludge thickener > Centrifugal sludge thickener > Water separator and Composting










-

Binh Hung Hoa

30,000

CSS

Aerobic pond

Grit chamber > Aerobic Pond > Stabilization Pond 1, 2 and 3









Phu My Hung Corp

Canh Doi

10,000

SSS

OD

Bar screen > Mesh screen > Grit chamber> Oxidation ditch with settling channel > Disinfection






Binh Duong

BIWASE

Nam Thu Dau Mot

17,650

SSS

ASBR

Screen > Aerated grit chamber >ASBR >UV disinfection > Stabilization pond






Soc Trang

Soc Trang UWC

Soc Trang

17,500

CSS

Preliminary clarifier

Bar screen > Mesh screen > Aerated grit chamber > Primary clarifier tank

Sludge digesting pit > Sludge drying bed











Note:

  • CSS: Combined Sewerage System

  • SSS: Separate sewer system;

  • OD: Oxidation ditch;

- SBR: Sequencing Batch Reactor;

- ASBR: Advanced Sequencing Batch Reactor



  • CAS: Conventional, Activated Sludge;

  • TF: Trickling filter;

- WSP: Wastewater Stabilization Ponds,





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