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.