Transcript Slide 1

Changing paradigm for sewage from treatment to recycle
 Prof. A.B. Gupta


Professor, Department of Civil Engineering,
Malaviya National Institute of Technology,
Jaipur
OUTLINE OF PRESENTATION
 National scenario for sewage treatment
 An overview of biological process
Principal organisms responsible for wastewater
treatment.
key factors governing biological growth.
Different options for suspended growth and fixed film
systems, their application and limitations
The changing scenario
Importance of Water
Water Cycle
The importance of water supply with sufficient quantity and
acceptable quality has been emphasized in the Millennium
Development Goals (MDG), drawn from the United Nations
Millennium Declaration.
Goal 7 of the MDG: ‘Ensure Environ Sustainability ’
Target 10 of Goal 7: ‘Halve, by 2015, the proportion of
the people without sustainable access to safe drinking
water and basic sanitation ’
Water for Life Decade: 2005-2015
UN declared 2005-2015 “Water for Life” as the International Decade
for Action and set the world agenda on a greater focus on waterrelated issues.
Sector-wise Water Requirement
Water Demand in km3 ( or BCM)
Sector
Standing Sub-Committee of
MoWR
NCIWRD
Year
2010
2025
2050
2010
2025
2050
Irrigation
688
910
1072
557
611
807
Drinking Water
56
73
102
43
62
111
Industry
12
23
63
37
67
81
Energy
5
15
130
19
33
70
Others
52
72
80
54
70
111
Total
813
1093
1447
710
843
1180
Source:
“STATUS OF WATER SUPPLY, WASTEWATER GENERATION AND TREATMENT IN CLASS-I CITIES &
CLASS-II TOWNS OF INDIA “, CPCB, CUPS/ 70 / 2009 - 10. December 2009
Is Enough Water Available? (m3PC-NatAvg)
2% of World’s Land Area
4% of World’s Fresh Water Resources
17% of World’s Population
India Landscape
Real GDP Growth / Population
9.6%
8.2%
1.05B
Challenges:
1.3B
Market Trends :
 GDP growth… High growth rates expected driven by internal
consumption and international demand.
 Rising Middle Class … As big a market as any leading
1.8 of technology,
European country. Awareness & Acceptance
Subsidizing energy efficient pumping systems. Seeking quality.
 Urbanization and Infrastructure development … 2nd &
3rd tier cities pick up momentum … building & municipal
segment growth
 Government Focus … Focus on Infrastructure
development… Water supply and wastewater recycle projects,
highways, bridges & irrigation schemes
 Infrastructure … Governments has now liberalized this sector allowing private player. Will
continue slow growth for next two years.
 Strengthening of US$ … pressure on imports, will drive localization. Tariff [29%] barrier. Very
mature manufacturing exists.
 Fresh Water Scarcity … India has 14% of World population on only 4% of its water resource. In
its path of becoming the most populous nation, lot of investment in water redistribution, treatment
and conservation.
 Urbanization … Has just started with almost 500 million people expected to urbanize over the
next 40 years. Huge investments in buildings and municipal segment is forecasted.
Positive
driver
Negative
driver
Neutral
6
Status of Municipal Wastewater
Generation and treatment capacity
Metropolitan Cities
• 15,644 MLD sewage generated in 35 metropolitan cities (>10
Lac)  8040 MLD treatment capacity (51.4%)
Class-I Cities
• 19894 MLD sewage generated is in 463 Class-I Cities (>1 Lac
but <10 Lac)  3515 MLD treatment capacity (17.66%)
Class-II Towns / Cities
• 2696.70 MLD sewage generated in 410 towns (>50,000 but
<1 Lac)  233.7 MLD treatment capacity (8%).
Municipal Corporations-Overview
Corporations - Overview
Municipal
1. The Municipal WW treatment technology adopted in India can be
broadly classified as:
1. ASP (Conventional & Extended Aeration, SBR) – 60%
2. UASB/UASB-Polishing Ponds – 15%
3. Aerated Lagoons & Stabilization Ponds – 20%
4. Trickling Filters/SAF/Fluidized Aerobic Bed – 10%
5. Micro STPs & MBR – 5%
2. However the preferred technology is ASP type largely due to the lesser
capital cost & simpler operation. MBR technology has major limitation
owing to its high capital cost and recurring membrane cost every 3-4
years which can be 25-40% of the total project cost.
8
BIOLOGICAL PRINCIPLES OF
WASTE WATER TREATMENT
Biological TP: a method of contact between
microbes and substrate. Suitable
temperature, pH, nutrients etc. are
required for microbial growth. Such a
growth results into the ‘removal’ of
substrate.
Role of microbes
-
O2
consumption
GROWTH - CELL DIVISION
INCREASE IN BIOMASS
(assimilation)
2.0m
ORGANIC
POLLUTANT
AND NUTRIENTS
(C,P,N,O,Fe,S…)
SINGLE
BACTERIUM
Controlled release of energy
Slow Burning!
CO2 evolved
(dissimilation)
Important organisms in w/w
treatment
• Bacteria
• Fungi
• Nemotodes
Important organisms in w/w
treatment
• Algae
Important organisms in w/w
treatment
• Protozoa
Stentor
Paramecium
• Rotifers, ciliates,
crustaceans
Celops
Activated Sludge Process
Activated Sludge Process is the
suspended-growth biological treatment
process, based on providing intimate contact
between the sewage and activated sludge.
Conventional ASP
16
Biological Nitrogen removal
Process Description
Nitrosomonas
NH4+ + 1.5O2
NO2- + 2H+ +
H2O
nitrobacter
NO2- + .5O2
NO3-
Synthesis
4CO2 + HCO3- + NH4+ + H2O
C5H7O2N + 5O2
SINGLE SLUDGE SUSPENDED
GROWTH SYSEM
TWO SLUDGE SUSPENDED
GROWTH SYSTEM
DENITRIFICATION
Nitrogen present in the sewage in the form
of nitrate is converted to nitrogen gas in a
series of steps that escapes from sewage.
NO3- NO2- NO- N2O- N2
Advances in Biological N- removal
• Application of Thiosphaera pantotropha, a
heterotrophic nitrifier and aerobic denitrifier, in mixed
bacterial cultures for simultaneous carbon removal,
nitrification and denitrification
• Two important points to note about TP
• i) The specific nitrifying activity of TP is 10 – 103
times lower than that of autotrophs much higher
compared to those of other het nitrifiers (103 - 104
times lower).
• Growth of TP as heterotroph is much higher than that
for the autotrophs (the max for Nitrosomonas
europea 0.03 - 0.05 h-1, that of TP approx 0.4 h-1)
• The aerobic denitrification rates were much higher
than het nitrification rates of TP- extra capacity to
take nitrate or nitrite coming from other routes
Deep shaft process
•It is a Process having a mechanism of great depth
aeration (depth of 40 to 150 m as an aeration tank) and it is
practiced where land is in short supply.
•It can treat the waste water at higher rate.
•It is also known as a space efficient and energy efficient
biological process.
LAGOONS
LAGOONS
• Lagoons are deep waste stabilization ponds -like
bodies of water or basins designed to receive,
hold, and treat wastewater for a predetermined
period of time by artificial means of aeration.
• In the lagoon, wastewater is treated through a
combination of physical, biological, and chemical
processes.
AEROBIC AERATED
LAGOONS
• Dissolved oxygen is present throughout much of
the depth of aerobic lagoons.
• They tend to be much shallower than other
lagoons.
• They are better suited for warm, sunny climates,
where they are less likely to freeze.
• HRT = 3 TO 60 days.
Applicability
Type of Lagoon
Application
Aerobic Lagoon
Municipal and industrial wastewaters of
low to medium strength.
Facultative
Lagoon
Treated raw, screened, or primary
settled municipal wastewater and
biodegradable industrial wastewaters.
Attached Growth
Systems
Trickling Filter
Biofilm or bacterial film or biomass is
grown or developed on solid
medium. Such as rocks, stone
pieces, synthetic medium etc. This
media is randomly packed in reactor.
Wastewater is applied on the top
through a rotating arm and it trickles
down of the bottom. In its travel to
the bottom of TF, wastewater is
brought into the centre of biofilm
attached to the medium. The process
may be depicted as shown below.
Changing Scenario
for
Wastewater treatment
1980
2010
32
Sewage disposal to recycle
Previously
Resi &
Commercial
Buildings
Sewage Treatment
Plant
DISPOSAL
Presently
Resi &
Commercial
Buildings
Sewage
Treatment Plant
100% RECYCLE
for Non Drinking
Applications
Recycle
0%
DISPOSAL
33
…Changing Scenario
Low Tech
Low Cost
Cost Benefit
Analysis
L1
34
Disposal and recycle norms…
Parameter
Disposal
norms
Recycle norms
Low end reuse
High end reuse
TSS
100
<5
< 1 ntu
BOD
100
< 10
Nil
COD
250
< 50
Nil
SDI
No limit
No limit
<3
TKN
100
No limit
<1
T- N
No limit
No limit
<5
T- P
5
No limit
<1
No limit
No limit
Nil
Bacteria
35
…Cost Benefit Analysis
1.
Benefit vs Additional cost
2.
Payback of Additional cost
3.
Life cycle analysis
36
Centralized vs. Decentralized Treatment Systems
• Current “conventional” practice:
– Design of larger treatment systems (>3500 m3/day)
• Capture of economies of scale
• However, small communities have different
characteristics and needs
– Bringing wastewater from many small sources to one
single location for treatment may not always be the
best option.
Decentralized Treatment Systems
WHERE to consider (according to USEPA)?
• Where the operation and management of existing onsite systems
must be improved
• Where the community or facility is remote from existing sewers
• Where localized water reuse opportunities are available
• Where fresh water for domestic supply is in short supply
• Where existing wastewater treatment plant capacity is limited and
financing is not easily available for expansion
• Where, for environmental reasons, the quantity of effluent discharged
to the environment must be limited
• Where the expansion of the existing wastewater conveyance from
treatment facilities would involve unnecessary disruption to the
community
• Where specific wastewater constituents are of environmental
concern.
limitations of conventional activated
sludge process….
39
limitation of conventional ASP….
• Settling units are prone to problems of
sludge rise, bulking , deflocculation, foaming
• Complete plant operation is normally
operator dependent
• No mechanism to control type of microorganism in the aeration tank
• N and P removal difficult
40
how to overcome these
problems…….?
41
RBC
• The RBC is a fixed media filter in which
the microorganisms are housed on a
series of large discs. These discs are
supported on a single shaft which is slowly
rotated through the wastewater by an air
or electric driven motor. The RBC is
covered by a removable fibreglass
housing which has access portals at each
end.
Nomenclature:
……….RBC……
RBC at MNIT
Advantages of RBC
•
•
•
•
Low F/M ratio resulting in higher efficiency
Low HRT hence compact
Low head loss and lower power requirement
Inherent simplicity and low operational and
maintenance cost
• Ability to resist shock loads
• Ability to lend itself to modular fabrication to suit
required effluent quality
Rotating Media Bio Reactor
Filters
Powder coated
Body
PLC Panel
Sequence Batch Reactor (SBR)
1. Fill
2. React (Aerate)
3. Settle
Screened /
degritted
Influent
TWL
4. Decant
5. Idle
Effluent
Sludge
49
SBR
Screened Influent
Baffle Wall
Mixers
Pre-react Chamber
Diffusers
Main-react
ITT Corporation India Pvt.Ltd.
Chamber
SAS
Pumps
Decanter
Effluent Discharge
50
SBR Basin Equipment
Dissolved
Oxygen
Ultrasonic
Level
Float Switch
Decanter
M
Penstock
M
From
Influent
Effluent
Inlet Works
Air Inlet Valve
M
Air Flow
To SAS
Storage
SAS Pump
M
S
Grid 1
Grid 2
Grid 3
Air Purge
Blowers
51
Outlet quality (all units in ppm)
Srno Parameter
SBR
ASP
1.
BOD
10
30
2.
COD
50
250 – 300
3.
TSS
10
100
4.
TN
<5
No change
5.
TP
<1
No change
52
MBR
Membrane Bio - Reactor
technology
53
MBR
it is a very high efficiency process
with outlet quality as feed to
Reverse Osmosis ….
54
areas of application….
• as pretreatment to RO , in place of
conventional ultra filtration systems
(Singapore experience)
• To achieve very high efficiency of more than
98%
• To have most compact layouts
55
MBR System Schematics
AIR
INLET
56
Outlet quality (all units in ppm)
Srno
Paramete
r
1.
BOD
10
5
30
2.
COD
50
25
250 – 300
3.
TSS
10
< 0.5
100
4.
TN
<5
<5
No change
5.
TP
<1
<1
No change
5.
SDI
-
<3
-
SBR
MBR
ASP
57
Energy considerations
• ASP STP Jaipur North- 27 MLD- 0.89 kWh/ kg of BOD (ref_ MNIT)
• ASP STP Jaipur South- 62.5 MLD- 0.50 kWh/ kg of BOD (ref_
MNIT)
• ASP Pune – 17 MLD ASP- 1.75, TF- 0.70 kWh/ kg of BOD (ref_
MNIT)
Ref-Compendium..IIT Kanpur prepared for NRCD- MOEF 2009
• Conventional ASP based STPs under YAP- Allahabd 60-80
MLD- 180-225 KWH/MLD
• TF under YAP- 180 KWH/MLD
• UASB under YAP- 10-15 KWH/MLD
• Facultative aerated lagoon under YAP 18 KWH/MLD
The case study of Jaipur
• Two scenarios considered
– First, centralized treatment at STP Delawas
and supply treated sewage through a pipeline
to the major green belts- data derived mainly
from PHED report
– Second, isolated RBCs for the desired
capacities to be constructed at individual
locations with and without automation
• Estimates made for a period of 10 years
Economic Justification of
Decentralized System
Table-1: Demand Estimates and No. of Proposed Plants
AREA
Tentative
No. of Plants
Demand in MLD
1 MLD
0.5 MLD
S.No.
Zone I
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Ram Niwas Bagh
Central Park
Polo Ground1.0/ Golf Course
SMS Stadium
Jawahar Nagar
Jawahar Nagar Forest Area
Amrita Devi Udyan
University Campus
Saras Sankul
MNIT
OTS
Smrity Van
Malviya Nagar sector 1
Malviya Nagar Ind. Area
Malviya Nagar sector 9
Jawahar Circle
Jagatpura
Pratap Nagar
SUBTOTAL
1.2
1
0.45
0.6
1.56
5
3
1
0.3
0.7
0.3
0.3
0.7
0.95
0.7
0.55
5
3.85
27.16
1
1
3
Central Park plant may Cater
1
5
3
1
1
1
OTS Plant may cater
2
1
1
1
5
4
26
4
Table-1: Demand Estimates and No. of Proposed Plants
S.No.
AREA
Tentative
Demand in MLD
No. of Plants
1 MLD
0.5 MLD
Zone II
1 Inter State Bus Terminus
0.25
2 Mansarovar (Sec 1 to 6)
1
1
3 Mansarover Sector SFS &Sec 7-12
1.2
1
1
4 Mansarover Industrial Area
1.2
1
1
3.65
3
3
1 Sitapura Ind. Area
2
2
2 Tonk Road
8
8
SUBTOTAL
10
10
22.5
23
2 Bagru Industrial Area
5
5
3 Ajmer Road Colonioes
5
5
32.5
33
0
72
7
72
3.5
SUBTOTAL
1
Zone III
0
Zone IV
1 Sez
SUBTOTAL
Total No. of Plants
Total Capacity
73.3
Unit Costs for various options
Plant Size
Treatment System without
Tertiary Treatment
Treatment System with
Tertiary Treatment
Treatment System with
Fully Automatic Plant
Capital Cost
Power Cost
for 10 Yrs
10 Yrs O & M
No. of
Cost
Proposed Units
1 MLD
7,875,000
3,966,564
3,212,394
72
0.5 MLD
6,900,000
1,983,282
3,121,833
7
1 MLD
8,400,000
5,949,846
3,212,394
72
0.5 MLD
7,485,000
2,974,923
3,121,833
7
1 MLD
8,925,000
5,949,846
586,130
72
0.5 MLD
8,070,000
2,974,923
495,569
7
Total Cost Estimates
No. of Proposed
Units
Without Tertiary Treatment
With Tertiary Treatment
Fully Automatic Plant
Centralized System
Capital Cost
Power Cost
for 10 Yrs
10 Yrs O & M
Cost
Total
72
567,000,000
285,592,622
231,292,350 1,083,884,972
7
48,300,000
13,882,975
615,300,000
299,475,596
253,145,181 1,167,920,777
72
604,800,000
428,388,933
231,292,350 1,264,481,283
7
52,395,000
20,824,462
657,195,000
449,213,395
253,145,181 1,359,553,575
72
642,600,000
428,388,933
42,201,345 1,113,190,278
7
56,490,000
20,824,462
699,090,000
449,213,395
45,670,328 1,193,973,722
1,050,000,000
989,600,000
236,400,000 2,276,000,000
21,852,830
21,852,830
3,468,983
84,035,805
95,072,292
80,783,445
Technologies for the Treatment of Wastewater
an analysis…
Each situation is different and needs to be given
dual consideration, different alternatives exist for
each system from small scale households to large
scale centralized one.
More attention to properly designed lower-cost,
simpler to operate processes as well as to
decentralized technologies. These should be
adopted depending on the influent wastewater and
on the desired effluent quality.
Also, whenever feasible, a reuse component
should be included for all new wastewater
treatment projects
Conclusion
• The selected strategy needs to be developed
through careful planning and detailing and may
be public consultation.
• The decentralized option has a definite edge
over the centralized option economically, and
the flexibility of modular development can
always allow stage wise development and
obtaining feedback to refine the system.
• The future is for the advanced technologies and
the life cycle analysis of the treatment options