Challenges and goodpractices of decentralized
domestic wastewater
treatment in China
Dr. Meixue Chen
Rural Wastewater Management Division,
Department of Rural Infrastructure
Construction ，Ministry of Housing and UrbanRural Development
Sep. 27, 2016

Rural areas

North east

North west

North of China
Middle southWest south
South of China

Wastewater in different regions
Domestic water use（L/P.day）
Northeas

Types of village

North southNorthWest northWest southSouth

80-13590～200100~14575～14080-160100～18040-90

80～100

40~80

50～90

60-12060～120

40-70

60～90

30~50

30～60

40-80

50～80

20-40

40～7020~40

20～35

20-50

40～60

t

Good economic，bath ,flush
toilet ,wash mashine
Good economic, bath andkitchen
Normal economic ,simple
toiletNo flush toilet

Characters of pHwastewater（mg/L）
SS
COD
BOD

5

6.5~8.5

100-300

6.5-8.0

NH4+-NTP

100-400

50-3003-50

1.0-6.0

150-200

200-450200-300

20-90

2.0-6.5

6.5~8.5

100~200

70～300150~45020~50

1.5~6.0

6.5~8.0100~200

200~450200~300

20~90

2.0~6.5

West north

6.5～8.0150～200

150～400

100～15020～50

2.0～6.0South

6.5~8.5

100~200

100~300

60~15020~80

2.0~7.0West south
Northeast
North south
NorthTechnical guide for rural domestic wastewater
treatment in different regions
Northeast: septic tanks, anaerobic biofilter, bio-contact oxidation
tank, land treatment, constructed wetlands, lagoon
North China : septic tanks, sewage digesters, aeration tank, sequencing
batch bio-reactor, oxidation ditch, biological contact oxidation , constructedwetlands, land treatment
Northwest :septic tank, anaerobic digesters, anaerobic biofilter,
constructed wetlands, land treatment
Southwest: septic tanks, wetland, land treatment, anaerobic technology,
bio-contact oxidation tank, oxidation ditch, anaerobic biofilter
Middle south: septic tanks bio-contact oxidation, oxidation ditch,
constructed wetland, lagoon, floating islands could be applied for sewage
treatment.
southeast: septic tank, anaerobic biofilter, anaerobic digesters; biologicalcontact oxidation tank, oxidation ditch, constructed wetlands, ecologicalfilter.

Domestic wastewater treatment rate in 2011year
100Treatment rate %

90
80

town

70

township60

village

50
40
30
20
100

Up to the and of 2010, 22.9% of domestic wastewater from towns andvillagesConstruction of villages

From 2008 to 2010

Rural wastewater(13% spray drain, andwastewater treatment)Pollution loads

townvillage

T&Vcity

SV(108m3/a)

3.6

5.6

9.2

33.0

COD(106t/a)

2.6

5.4

8.0

8.6

N(106t/a)

0.5

1.1

1.6

0.97

P(106t/a)

0.04

0.07

0.11

SV: sewage volume

Types of decentralized wastewater systems• Primary treatment– Septic tank

• Secondary treatment----Biological technologies– Biofilm– Anaerobic digesters• Eco-technologies– Constructed wetlands– Leach trenches• Community Systems

土地处理treatment

LandOxidation
氧化塘pondConstructed
人工湿地
wetland

MBR

活性污泥Activatedsludge

接触氧化池
Biologicalcontactoxidation

Anaerobic
厌氧生物膜biofilm

Anaerobic
沼气池
tank化粪池
Septictank

Technologies
Th l i forf decentralize
dt li
wastewater treatment in villages

100%

80%

60%

40%

20%0%

W t
Wastewatert treatmenttt
t technologies
t h l i initowns
AS

BF

LTOP

Funding资金来源汇总表

AS: Activated Sludge
BF: Biological Filter
LT: Land Treatment
OP: Oxidation Pond

BOT（build-operate-transfer）

政府自运营TOTBT其它托管BOT

Case study: Septic tankeffluent•Inexpensive•Simple to maintain

Influent

the firsttank

the secondtank

the thirdtank• Sludge may cause an odor problem• Not effective in removing nitrate andphosphorus and pathogenic organics• Potential pollution source ofgroundwater

Case study: Activated sludge

1m³,2m³,5m³,10m³,15m³/day• Flexible for decentralize wastewater treatment• Automatic control• Expensive for single family• management is relative complex

Case study: Constructed wetland
Plant

Water
distribution

Effluent
Waterbody

GrassWetland
Water-proof• constructed cost
• flexible land use
Small-scale decentralizedsystem• Low removal rate

0.2-5m3/d• Management

Case study: Leach Trenches
AA’

Ф75mm

Ф110mm
覆盖层细滤层

碎石(Ф10-30)

砾石(Ф5-10)精虑层

PVC 管粗虑层• Constucted and operation simple• Low cost
• pollution of groundwater• Poor quality of effluent

Case study: Cluster system

Wasterwater

Discharge

ScreenBiofilter• Cluster system• High quality of effluent

Constructed wetland••

60m3/d，for 900 persons
floor area: 250m2

Decentralized wastewater systems
For COD removal

Aeration processFor nitrogen removal

Bio+Eco Treatment

Situation•••

Lack of knowledge of decentralized systems
Lack of long-term operation data
Management needed– systems are a cost-effective and long-term option
for meeting public health and water quality goals– Who is responsible? Typically homeowner for
onsite，Inadequate methods of needs assessment

Promotion Plan—Funding• PPP（Public-Private-Partnership）• The main body of construction andoperation management : Enterprises• Local government is mainly to buy
services included in the annual budget

Promotion Plan—Classification technical guidance
Basic principleclassification, in situ reduction

The urban guiding the rural development
Decentralized treatment
Economic application, management is simple
21

Actions
13th Five-Year Plan: Rural Residential
Environment Improvement Actions•••

Integration of urban and rural development
The development of social undertakings in ruralareas
Urban public services extend to rural areas

Actions
Demonstration of one hundred counties
98%

95%

Unified• Planning• Construction• Management• Operation

65%
40%
20%

10%
Wastewater
treatment
ratio

Facilities
good rate

20082014

Working rate

Changshu model
Regional
integrated
propulsion

Government
purchaseservice

Unifiedoperation ofthe company

Thanks for your attention!