Some Natural Treatment Systems for UrbanSome Natural Treatment Systems for Urban Waste Water

CHANDAN MAHANTADEPARTMENT OF CIVIL ENGINEERING

Bharalu River, Guwahati

Originates as Basistha River in Meghalaya hills to discharge into Brahmaputra

The most polluted and contaminated of all the tributaries of the Brahmaputra

The Bharalu at present…

Serves as the natural drainage for storm water runofffor storm water runoff

Receives a large portion of the city’s municipal industrial and other wastesmunicipal, industrial and other wastes

Some steps for conservation of the urban river…

Preliminary Investigation Operation & Maintenance

Identification of degraded stretches & localities

Public Awareness & Public participation

Selection of localities in order of priority HRD and Capacity Building

Collection of information for system and component design

Project management & institutional issues

Design of system and components

Monitoring and evaluation

Sampling points along Bharalu River

Conductivity variationd ti it (D )

TDS variation

Water quality

0.80.9

1

m)

conductivity(Dec)conductivity(April)Des. limit Max. per. limitConductovity(August)

2000

Dec Apr Augu

Des; limit Max: per limit

0.20.30.40.50.60.70.8

ondu

ctiv

ity(m

S/c

0

500

1000

1500

TDS

(ppm

)

00.1

1 2 3 4a 4b 4m 5 6 7a 7b 7m 8 9 10 11Sampling points

co 01 2 3 4a 4b 4m 5 6 7a 7b 7m 8 9 10 11

station

Alkalinity variation BOD variationAlkalinity variation

500550600650

)

Alkalinity(April) Alkalinity (August) Max Per. Limit

BOD variation

2224262830

BOD(Dec) BOD(April) BOD(August)

Des limit Max. per. limit

50100150200250300350400450500

Alk

alin

ity(p

pm)

468

10121416182022

050

1 2 3 4a 4b 4m 5 6 7a 7b 7m 8 9 10 11

Sampling points

024

1 2 3 4a 4b 4m 5 6 7a 7b 7m 8 9 10 11

Sampling points

T t l Ph h

Water quality

Chloride variation(Max. Per. limit=250ppm

80

90

100

Chloride (Dec) Chloride (April) Chloride (August)

Total Phosphorus

5

6

T P(Dec) T P(April) T P(Aug)

Des. limit max per limit

20

30

40

50

60

70

Chl

orid

e (p

pm)

1

2

3

4

T P(

ppm

)

0

10

20

1 2 3 4a 4b 4m 5 6 7a 7b 7m 8 9 10 11

Sam pling points

01 2 3 4a 4b 4m 5 6 7a 7b 7m 8 9 10 11

Sampling points

Hardness Variation

180200

Hardness (Dec) Hardness (April)

Hardness (August) Highest des: limit

Sulphate variation

Sulphate (Dec) Sulphate (April)Sulphate (August) Highest Des limitMax per limit

Calcium variationCalcium (Dec) calcium(April) Calcium (August)

Des limit Max Per.Limit

6080

100120140160180

Har

dnes

s (p

pm)

200

300

400

500

Sulp

hate

(ppm

)

Max. per. limit

500600700800900

1000110012001300140015001600

alci

um (p

pm)

02040

1 2 3 4a 4b 4m 5 6 7a 7b 7m 8 9 10 11

Sampling points

H0

100

1 2 3 4a 4b 4m 5 6 7a 7b 7m 8 9 10 11

Sampling points

S

0100200300400500

1 2 3 4a 4b 4m 5 6 7a 7b 7m 8 9 10 11Sampling points

Ca

Population estimatesPopulation estimates

8

Restoration of Bharalu…a watershed level strategy

Creation of Buffer zone

To prohibit building construction

To intercept the main contributing drain in the buffer zone before meeting th i l ith ll lthe river along with parallel trunk line

To initiate River Front Development

Buffer zone

NATURAL TREATMENT SYSTEMS- for wastewater treatment of urban water bodies

RIVER BED FILTRATION

WastewaterWastewater

Banks of Rivers orLakes

Extraction Wells

Extraction WellsSchematic Diagram of a typical Bank Filtration W llExtraction Wells Well

Source: http://www.wrrc.hawaii.edu

Drinkable Water Pretreated water for further purification

SOIL AQUIFER TREATMENT (SAT)

Controlled Passage of Effluent

Low Technology, AdvancedWastewater Treatment System

Spreading Basins for Wastewater InputWastewater Input

Aquifer Zone

Reclaimed water fort blnon- potable use

Source: http://watersmartproject.org/sat/sat.htm

CONSTRUCTED WETLANDS

WastewaterWastewater

Inlet Zone

Porous Medium (Aerobic,Anoxic and Anaerobic zones)and Anaerobic zones)

Outlet Zone Schematic Diagram of a typical Constructed Wetland

Source: Vymazal, 2009

Tributary or River  Brahamputra

Municipal Dischargeof selected locations

Contaminated Ground water

ed

Pretreatment

Pretreatment

For each approach:

• Source?e ad

dres

se

Source?

• Application?

• Bottlenecks?

• Technological challenges?need

to b

e

Bank filtration Constructed wetlands

Soil aquifer treatment

Technological challenges?• Pre‐ or post‐treatment steps required?

• Typical scale?

E i f ibili ?

aspe

cts

n

Post-treatment

Post-treatment

• Economic feasibility?

• Social acceptability?

oint

: whi

ch

treatment treatment

tarti

ng p

o

Supply of Urban consumptive/ Non‐consumptive water

Non Consumptive usesSupply of Urban consumptive water

St

Rivers/Lakes

Anticipated Bottlenecks:• Clogging of wells• Caking• Mixing of incompatible components of surface and ground water• Geogenic components (arsenic, fluoride, other contaminants) Ch i t lit d tit ( S l d Cli ti Ch i bilit )• Changes in water quality and quantity ( Seasonal and Climatic  Change  variability)

• Finding the optimal bank/well distance • Community  reluctance  (Social and Cultural)• Social  and gender inequities in term of access • Local knowledge perceptions and capacities and the new technology too far: subtraction of ground watergtoo near: poor purification capacity

Pre‐ and post‐treatment• Underground aeration• Anaerobic post‐treatment• Activated carbon/O3/UV/membrane for organic micro‐pollutantsChallenges/research topicsy

poin

ts

Bank filtration

Challenges/research topics• What hydrogeological conditions required for optimal purification?• Consistency of hydrological attributes?• Affordability and  acceptability issues?• Which components are present in the soil and what is their influence on water quality?• How to maintain an optimal flow of water?tra

tion:

key

Post-treatment

• What is the compatibility of the different water streams (river water – ground water)?• How to deal with varying water quality and quantity?• How to develop a methodology to determine the optimal bank/well distance?• Is there added value in using underground aeration?• Which post‐treatment steps are necessary?B

ank

filt

treatment• Scaling and optimized design of the systems ?Economic considerations• Design of low‐cost solutions• Issues related to possible cost recoverySocial implicationsWilli / l f l f di l• Willingness/reluctance of people to pay for water directly.

• Protection of the collection area (in particular with respect to hygiene)• How to increase  people’s appreciation of the  quality   aspect of water• How to ensure political will • Acceptation and sustainable  community management of system developed

Drinking water

Rivers/Lakes Specific Research Topics:• Catchment characteristics including hydro geological settings• Optimal bank/well distance modelingrtn

ers

Optimal bank/well distance modeling• Underground aeration• Compatibility of water stream with ground water• Well design• Varying water quality and quantity• Fluoride , arsenic and other metal/metalloid contaminantsor

tium

par

• Ownership and Social equity issues• Governance

and

cons

o

Bank filtration Partners/ Stakeholders• WRD• PHED• CGWBqu

estio

ns

Post-treatment

• GMDA• PCBA• Community• IITG

rese

arch

q

treatment

filtra

tion:

Consumptive water

Ban

k

Gray water/Storm water

Bottlenecks:• What is the feasibility of water separation• To what extent can the water be treated (metals/drugs/etc)• Type of macrophytes and microbes

Pretreatment

Pre‐ and post‐treatment• Fermentation (depending on stream in)• Soil aquifer treatment (post) ?• Other treatment steps (post)

Challenges/research topicsnts

Challenges/research topics• What biological/biochemical conditions are required for optimal purification?• What are the requirements to obtain separated water streams?• Is fermentation necessary as a pre‐treatment step?• Which design is optimal?• Which macrophytes and microbes should be used?s:

key

poi

n

Constructed wetlands

p y• What is the  treatment capacity of constructed wetlands?• Which materials should be to construct a wetland?• What is the optimal size and volume of the wetland?• Which post‐treatment steps are required?

d w

etla

nds

Post-treatment

Scale• Relatively large area required• Relatively small scale (At the level of inhabitation)

Social implications• Separation of waste streamson

stru

cted

treatment • Separation of waste streams• Accepting reuse of waste water• Protection of the wetland area• How to get people accept reuse treated water • To promote constructed wetlands as a viable option for reuse of waste water

Co

Industrial waterIrrigation water

Non‐consumptive uses

Gray water/rain water

Specific research topics:olde

rs

Pretreatment

Specific research topics:• Biological/Biochemical and Ecological• Separated water streams• Macrophytes and microbes• Wetland design• Fermentation pretreatmentnd

sta

keho

Fermentation pretreatment• Post treatment techniques

estio

ns a

n

Constructed wetlands

Partners• WRD• PHEDse

arch

qu

Post-treatment

• PHED• CGWB• GMDA• PCBA• Community• IITGet

land

s: re

s

treatment

truct

ed w

e

Industrial waterIrrigation water

Other non‐consumptive uses

Con

st

WetlandsRiver/Lake water

Bottlenecks:• Clogging• Caking• Soil components

Pretreatment

Pre‐ and post‐treatment• For river water: extensive pretreatment necessary (quick bank filtration? Wetland?)• Post‐treatment is dependent on pre‐treatment

Challenges/research topics• How to maintain an optimal flow?ts • How to maintain an optimal flow?• Which components are present in the soil and what is their influence on water quality? • What geological conditions are required?• What hydrological conditions are required?• Which type of well and drains are optimal?• For river water: which pretreatment step is necessary?t:

key

poin

Soil aquifer treatment

p p y• Which post‐treatment steps are necessary?• What is the optimal scale of soil aquifer treatment?• What is the optimal distance between infiltration and collection?

Scaletreat

men

t

• Site specific

Social implications• Protection of the infiltration zone• How to get people to appreciate water quality• Window dressing politics (real issues are avoided and not addressed directly)oi

l aqu

ifer

• Window‐dressing politics (real issues are avoided and not addressed directly)Need to pressure local governments from the top (drinking water organizations) and the bottom (people)

• Acceptation of the technique (get the local people involved)

So

Drinking water/Groundwater suppletion

Specific Research Topics:• Geology – Analysis of sub surface geology and their efficiency in waste water treatment,e.g. grain size, mineralogy , composition

• Physical and chemical characteristics of the soil media with respect to flow of water• Optimal infiltration/well distance modelingol

ders

Constructed wetlandsRiver water

Pretreatment

• Fluoride , arsenic and other contaminants• Well and drain design

nd s

take

hoes

tions

an

Soil aquifer treatment Partners/ Stakeholders

• WRD• PHED• CGWBse

arch

qu

• GMDA• PCBA• Community• IITG

atm

ent:

res

quife

r tre

aS

oil a Consumptive water/

Groundwater supplement

How people feel about the Bharalu River conservation?

People in the city are ready to lend a helping hand

Cultural sentiments associated with the river are pretty strong in some communities

People have less faith in the ability or intent of the government to change the river’s situation

People have a deep sense of failure and disappointment with actions taken by the Govt. so far

People tend to blame the Government for most of the ills facing the river and have limited realization of their roles

How do YOU feel about conservation of the Urban Water bodies?

W d t ith h iWe need to come up with a comprehensive strategy. May you be a partner in this effort!