Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
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!