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
|
|
| Technical requirements for effluent -
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
-
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
|
|
√
|
|
|
| -
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.
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).
-
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:
-
Mechanical treatment.
-
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).
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,
|
Chia sẻ với bạn bè của bạn: |