Technology Demand and Selection for Water Quality Upgrade of Beijing
Municipal Wastewater Treatment PlantMunicipal Wastewater Treatment Plant
Du Bing, Beijing Municipal Research Institute g, j g pof Environmental Protection
Presentation Overview
1. Water resources and environment of Beijing
2. The target of water quality upgrading and
corresponding technical demand
3. Beijing Qinghe Water Reuse Engineering 3. Beijing Qinghe Water Reuse Engineering
4. Existing problems and research direction
5. Conclusion
1. Water Resources and Environment of Beijing
1 Water Resources and Environment1. Water Resources and Environmentof Beijing
one of the most serious water-shortage cities in the world
a huge project of “adjustment water from south to north” a huge project of adjustment water from south to north
a plan called “Beijing reclaimed water utilization plan”
2. The Target of Water Quality Upgrade and g y pgCorresponding Technical Demand
2.1 the users of reclaimed water and their requirements2.1 the users of reclaimed water and their requirements
2.2 the target for effluent water quality upgrading
2 3 t t f WWTP di 2.3 strategy for WWTP upgrading
2.4 advanced secondary treatment
2.5 tertiary treatment
2.1 the Users of Reclaimed Water and their Requirements
According to different functions it can be assorted into four aspects:landscape water such as rivers and lakesaspects:landscape water such as rivers and lakes supplying water and gardening water, industrial water such as cooling and process water, municipal water such g p , pas road and vehicle washing water, and irrigation water.
Generally speaking, the surface water of Class IV (Table 2) y p g, ( )can meet all the requirements of reclaimed water. Therefore Beijing municipal government proposed that the high quality reclaimed water should be in accordance with the requirements of surface water of Class IV (except TN).
Table 1. Several Typical Water Quality Requirementsfor Reclaimed Water
Constituent CODcr/mg/L
BOD5/mg/L
TP/mg/L
SS/mg/L
TN / mg/L
NH4+-N/
mg/L pH Turbidity/ NTU
Total Hardness/
mg/L
Soluble Solid/mg/L
Chroma/ time
Faecal Coliforms/
No./L
6 5 8thermal power plant 1 38 — 0.3 10 — 1 6.5~8.5 9 280 700 — —
Groundwater artificial recharge2 15 4 — — — 0.2 6.5~8.
5 5 450 1000 15 3
Cooling, washing, 60 10~3 1 5 30 10 5 30 2000Cooling, washing, boiler2 60 10 3
0 1 5~30 — 10 — 5 — — 30 2000
Municipal use2 — 15 — — — 10~20 6.5~9.0 5~20 — 1000
~1500 30 1200
Landscape2 30 6 0 5 10 — 5 6.0~9. 5 — — 30 500Landscape 30 6 0.5 10 5 0 5 30 500
Agriculture, forestry, pasturage2 40~90 10~3
50.2~0.
6 30 — — 5.5~8.5 10 450 1000 30 2000
~10000
Note:1. adapted from reclaimed water quality requirement of one thermal power plant of Beijing.2. adapted from reclaimed water standard(SL-2006). p ( )
Table 2 Water Quality First Grade Discharge Standard ofTable 2. Water Quality First Grade Discharge Standard of Municipal Wastewater and Class IV Surface Water
Constituent CODcr/ mg/L
BOD5/mg/L
TP/mg/L
SS/mg/L
TN/mg/L
NH4+-N/
mg/L pH turbidity/NTU
Total Hardness/
mg/L
Soluble Solid/mg/L
Chroma/time
Faecal Coliforms
/No./L
First Grade- A1 50 10 0.5 10 15 5(8)4 6~9 — — — 30 100
First Grade -B1 60 20 1.0 20 20 8(15) 4 6~9 — — — 30 10000
Class IV of surface water2 30 6 0.33 — 1.5 1.5 6~9 — — — — 20000
High quality reclaimed water ≤30 ≤6 ≤0.3 <10 — < 1.5 6~9 <5 — <1000 <30 20000
Note:1. Discharge standards of water pollutants for municipal wastewater treatment plant,
reclaimed water
GB1318918-2002.2. Surface water quality standards(GB3838-2002).3. Related to lakes and reservoirs.4. Parameters in ( ) representing water temperature less than or equal to 12℃,( ) p g p q ,
parameters outside ( ) representing water temperature more than 12℃.
2.2 the Target for Effluent Water Quality Upgrading
Many WWTPs constructed early before 2002 were unable to remove nitrogen andwere unable to remove nitrogen and phosphorous.
R tl t WWTP t fitt d t Recently most WWTPs were retrofitted to upgrade its effluent to meet first grade-B’s
i t f th t d drequirement of the new standard.
Reclaimed Water in accordance with Class IV is suitable for most kinds of water utility except for drinking.
2 3 strategy for WWTP upgrading2.3 strategy for WWTP upgrading
WWTP upgrading consists of two aspects• advanced secondary treatment
• tertiary treatment• tertiary treatment
The difference between Table1 and Table2• advanced secondary treatment
• tertiary treatmenttertiary treatment
2 4 Advanced Secondary Treatment2.4 Advanced Secondary Treatment
Advanced secondary treatment is aimed to high efficiency removal of organic compounds andefficiency removal of organic compounds and nutrients (N、P). There are a wide variety of processes suitable for the purpose withprocesses suitable for the purpose with different specific applied conditions. These processes are presented schematically inprocesses are presented schematically in Fig.1~ Fig.3. Several suggested processes for existing WWTP upgrading and theirexisting WWTP upgrading and their characteristics are provided in Table 3.
2.4-1 single sludge system
Mixed Liquor Recycle
EffluentInfluent
Return Sludge
Anaerobic Anoxic Aerobic
Figure 1. 3 Stage Pho-redox Process (A2/O)
2.4-1 single sludge system
Recycle1 Recycle2
EffluentInfluentAnoxic AerobicAnaerobic Anoxic
SecondarySedimentation
Tank
Return Sludge
Tank
Figure2. MUCT Process
2.4-1 single sludge system
Influent(Q)
Effl t
Nitrified Recycle(400%Q)
( )EffluentSecondary
SedimentationTank
Return Sludge (100% Q) ExcessSludge
Anaerobic Zone Anoxic Zone Aerobic Zone
Figure 3. 5-stage Bardenpho Process
2.4-1 single sludge system
processProcess
Applied ScopeTarget water concentration
Table 3. advanced secondary treatment process selection
process Characteristic Applied ScopeCODcr BOD5 SS TN TP
①TBOD:TP<20:1② Efflunet TN<8~12
A2/O
Single sludge system with one anoxic zone
② Efflunet TN<8~12 mg/L ③ high rate process, apply to the rebuild of existing plants with
<50 <50 <20 <8 <3
existing plants with limited excess
Single sludge system with
① Efflunet TN<6~8 MUCT system with
two anoxic zones
mg/L② low rate process
<50 <10 <20 <6 <1
5 Stage Bardenph
o
Single sludge system with multi anoxic
① low rate process ② Efflunet TN<3 mg/L③ high efficiency for simultaneous
<30 <10 <15 <3 <1o zones denitrification and
dephosphorization
2.4 advanced secondary treatment2.4 advanced secondary treatment
Recently, as technology progresses of wastewater treatment, several new bioaugmentation nitrogen removal processes have been d l d Th i b ti lldeveloped. The organic carbon were rationally allocated and utilized meanwhile obligate bacteria were enriched and cultivated Fig 4 tobacteria were enriched and cultivated. Fig.4 to Fig.7 schematically present these processes of BABE In-Nitri OWASA BCFSBABE, In-Nitri, OWASA, BCFS.
2.4-2 multi-sludge system
Effl t
air
Influent Aerobic tankSecondary
Sedimentation
BABE
EffluentInfluent Aerobic tank
Return Sludge
SedimentationTank
Effluent
BABEReactor
ReturnSludge
g
supernant Dewateringsludge
gExcess Sludge
Sludgetreatment
(digestion+dewatering)
sludgetreatment
Figure 4. BABE Process
R
2.4-2 multi-sludge system
RawWastewater
PrimaryTreatedEffluentA ti T k
SecondaryPrimary
SedimentationTank
EffluentAeration Tank SedimentationTank
ExessNitrification
Sludge ThickenedP i Sl d
PrimanySludge
Thickening
WASThickening
Supematant
Primary Sludge
digesterNitrifiedDewatering
DewateringReturn Stream SludgeSide-stream
Liquid
Return Stream
Alkalinity
Dewatering
Sludge for
Nitrification
Alkalinity Disposal
Figure 5. Inexpensive Nitrification
2.4-2 multi-sludge system
Influent
Trickling FilterPrimarySedimentation
Tank
SNDSecondary
SedimentationTank
Tank
Effluent
VFATank
Fermenter
Sludge Excess Sludge
Anaerobic Zone Anoxic Zone Aerobic Zone
Figure 6. OWASA Process
2.4-2 multi-sludge system
Influent(COD, NH4
+, PO42- )
Effluent
Recycle A Recycle B
t t Mi d A biSecondary
S di t ti
Recycle CS di t tiIron
AnoxicAnaerobic contact Mixed Aerobic SedimentationTank
Phosphorous Sludge
ExcessSludge
Return Sludge
ySedimentationIron
Salts
Figure 7. BCFS Proces
Table 4. comparison of new bioaugmentation process to existing advanced secondary treatment process
Process Carbon Microorganism Denitrification and EngineeringProcess Types
Carbon Allocation and
Utilization
Microorganism Species and
Characteristic
Denitrification and Dephosphorization
Engineering Applications
New Bioaugmen-tation
① Reasonable allocation carbon② Utilization
Specific bacteria culturation
Combined biological phosphorus removal with
Less application, technology not nature② Utilization
of supernatant from sludge
removal with chemic phosphorus removal
not nature
fermentation(VFA)
Existing Ad d
①utilization of Mixed sludge f lti
biological h h
wide spread,t h lAdvanced
Secondary Treatment Process
exogenous carbon②Utilization of endogenous
of multi-species bacteria
phosphorus removal
technology nature
Process endogenous carbon
2.5 tertiary treatment2.5 tertiary treatment
Tertiary treatment starts with the final effluent of an advanced seconda t eatment WWTP Acco ding to diffe ent e sesecondary treatment WWTP. According to different reuse quality and purpose of water supply, different tertiary treatment process can be used to produce several classestreatment process can be used to produce several classes reclaimed water. The typical units or processes are listed in Table 5. Generally the tertiary effluent can be divided into 4 classes (Table 6). Every class water quality and its corresponding process is shown in Table 7.
l d l bl d hReclaimed water quality in table 7 demonstrates that tertiary 2 is in accordance with class IV of surface water standard.
Table 5. Treatment Technologies/Processes for Removal of Constituents in Wastewater for Water Reuse Applications
SuspSo
ColS o
PartiO
rgM
a
DissO
rgM
a
Nitr
Phos TrC
onst ToD
issSo
PathConstituents in Wastewater for Water Reuse Applications
Unit Operation or Process
pendedolids
loidalolids
iculateganicatter
solvedganicatter
rogen
phorus
racetituents
otalsolvedolids
ogens
Conventional Secondary Treatment × ×yAdvanced Secondary Treatment × × × ×Coagulation/Flocculation/Sedimentation × × × × × ×Depth Filtration × ×pSurface Filtration × × ×Microfiltration × × × ×Ultrafiltration × × × ×Dissolved Air Flotation × × × ×Nanofiltration × × × × ×Reverse Osmosis × × × ×Electrodialysis × × × ×Carbon Adsorption × ×Ion Exchange × × ×Advanced Oxidation × × × ×Disinfection × ×
Table 6. Reclaimed water classifications
Classification Characteristics
Advanced•For non-contact industrial uses with low concern for hardness and dissolved solidsAdvanced
Secondary solids•Base WWTP process train•Meets secondary-23 recycled water criteria
•For industrial uses with human contact potential and /or industries that require partial hardness and dissolved salt removal
Tertiary 1Conventional
require partial hardness and dissolved salt removal•Requires a coagulation / flocculation / sedimentation process with filtration •Removes some hardness and dissolved salts; provides some soluble organic removal and color removalMeets tertiary recycled water criteria•Meets tertiary recycled water criteria
Tertiary 2Membrane
•For industrial uses with human contact potential and / or industries that can use hard / high salt water•Provides soluble organic removal and color removal
Filtrationg
•Provides pathogen removal and reduces disinfection requirements•Meets tertiary recycled water criteria
Tertiary 3 For industries low dissolved salts •Requires tertiary 2 water followed by softening with RO or ED depending onMembrane
Softening
•Requires tertiary 2 water followed by softening with RO or ED depending on the target constituents•Meets tertiary recycled water criteria
•For industries requiring low dissolved salts and removal of trace constituents Tertiary 4Advanced
•Requires tertiary 3 water with RO and either ion exchange, carbon adsorption or advanced oxidation processes, depending on the target constituent.•Meets tertiary recycled water criteria
Table 7. Water Quality for the Reclaimed Water Classifications
Constituent
Reclaimed Water Concentration1
AdvancedSecondary
Tertiary 1Conventional
Tertiary 2Membrane
Tertiary 3Membrane Tertiary 4
AdvancedSecondary Conventional Filtration Softening Advanced
BOD, mg/L 5.0~10.0 ≤5.0 <1.0~5.0 ≤1.0 ≤1.0
TSS /L 5 0 10 0 ≤3 0 ≤2 0 ≤1 0 ≤1 0TSS, mg/L 5.0~10.0 ≤3.0 ≤2.0 ≤1.0 ≤1.0
Total Phosphorous, mg/L ≤1.0 ≤0.4 ≤1.0 ≤0.5 ≤0.5
Ammonia, mg/L ≤3.0 ≤2.0 ≤3.0 ≤0.1 ≤0.1
Nitrate, mg/L 10.0~30.0 10.0~30.0 10.0~30.0 ≤1.0 ≤1.0
Total Coliform3, No. /100mL
<23.0 <2.2 <2.2 Approx.0 Approx.0
TOC, mg/L 8.0~20.0 1.0~5.0 0.5~5.0 0.1~1.0 Approx.0
Turbidity, NTU 3.0 0.3~2.0 ≤1.0 0.01~1.0 0.01~1.0
TDS /L 750/1500 500/800 750/1500 5 40 5 40TDS, mg/L 750/1500 <500/800 750/1500 ≤5~40 ≤5~40
Hardness, mg/L as CaCO3
250/400 100/200 250/400 <30 <20
T C i V i bl V i bl V i bl V i bl A 0
Note: 1. Average or maximum effluent concentration of constituent. When two concentrations are given, these represent the average concentration for two different supplies: Source a (Average), Source B (Hard, High Salt).
Trace Constituents Variable Variable Variable Variable Approx.0
3. Beijing Qinghe Water Reuse j g Q gEngineeringg g
3. Beijing Qinghe Water Reuse j g gEngineering
Beijing Qinghe Water Reuse Engineering plant is an auxiliary project of Beijing Olympic Game. It y p j j g y pwas put into use in 2007. The reclaimed water was supplied to the central lake of Olympic Park. The design treatment capacity is 80 000 cubicThe design treatment capacity is 80,000 cubic meters per day.
As the TN removal was not considered in design gthe design effluent TN concentration was higher than that of the Class IV standard. This indicated that the TN removal was insufficient for this kindthat the TN removal was insufficient for this kind of process. There are potential risks of eutrophication.
Table 8. Summany of Influent and Effluent Data ofTable 8. Summany of Influent and Effluent Data of Beijing Qinghe Reclained Water Plant
Constituent BOD5/mg/L
CODcr/mg/L
SS/mg/L
NH4+-N/
mg/LTP/
mg/LTN/
mg/LTurbidity/
NTUchroma/
倍
Faecal Coliforms /
个/L个/L
Influent Quality 20 60 20 1.5 1 —— —— 100 10000Q y
Designed Effluent Q lit
6 —— 10 5 0.5 15 —— 30 10000Quality
Effluent Quality <2 <30 <5 --- --- ---- <100 <5 <3Quality
Influent EffluentPump Auto Collecting Membrane active WaterDistributionFreshInfluent
Ai
EffluentPump Station washing
lilter
Collecting Well Treatment
systemcarbon
filter
DistributionPump Station
Water tank
Backwash
agent
BackwashchlorideAir compressor Backwash
Figure 8. Process of Qinghe Reclaimed water plant
4. Existing problems and g presearch direction
4. Existing problems and research gdirection
Although the proposed reclaimed water quality nearly the same as Class IV of surface water but no limitation on TN is a potential problem. It is well known that phosphorous and nitrogen are the main factors for inducing eutrophication. The TN is not restricted because of the shortcoming of existingTN is not restricted because of the shortcoming of existing nitrogen removal technology and economic constrain.
Generally the lowest effluent TN and TP concentrations can be obtained for advanced secondary treatment process is about 3mg/L and 0.5mg/L respectively, High efficiency separation process such as membrane should be used for TP removal toprocess such as membrane should be used for TP removal to consistently achieve the effluent suspended solids concentration lower than 0.3mg/L. Therefore the TN and TP i i l h h ll i bl d di iintensive removal are the challenging problems and directions for future research.
5. Conclusion5. Conclusion
5. Conclusion Beijing has been facing serious water-shortage problem. It is a cost-
effective strategy to release the pressure with considering the WWTPeffective strategy to release the pressure with considering the WWTP secondary effluent as the new water resource to produce high quality reclaimed water.
With the existing WWTPs upgrade and tertiary treatment facilities With the existing WWTPs upgrade and tertiary treatment facilities implementation the reclaimed water which could meet the requirement of Class IV of surface water can be supplied to most of municipal water consumers.municipal water consumers.
The advanced secondary treatment progresses especially the new bioaugmentation technologies can be used in existing WWTP upgrade to effectively remove TN and TP in the municipal wastewater. Manyto effectively remove TN and TP in the municipal wastewater. Many tertiary treatment processes such as MF, UF, MBR, RO and their combinations are able to obtain high quality reclaimed water meeting the requirement of Class IV of surface water.q
The standard removal efficiencies of TN and TP current secondary and tertiary treatment processes should be improved. The TN removal should be the emphasis for new technology research andshould be the emphasis for new technology research and development.