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| 1. Greenfield or new water treatment plants based on Tube Settler technology / clarifiers read more... |
| 2. Single or multimedia gravity filter beds. read more... |
| 3. Complete water treatment systems and Water supply schemes read more... |
| 4. Augmentation or retrofit of existing plants for capacity or quality up-gradation read more... |
5. Mass application of small capacity standardized plants
read more... |
| 6. Sewage Treatment Plant. |
| 7. Project Management Consultancy. (PMC).. |
| 8. Civil, Structural, Electrical & Automation Engineering design & drawings. |
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| Research Paper & Presentation |
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Navi Mumbai Municipal Corporation
(NMMC) |
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| Introduction : |
In order to cater to the increasing water demand of the city of New Mumbai, Maharasjtra it was
proposed to augment the treated water capacity from the treatment plant complex from 300 mld
to 450 mld in the year 2010. The additional capacity required was 150 mld. The source of the
raw water is Morbee reservoir, located 8 km away from plant site. The raw water is conveyed to
the plant by gravity. There was severe space constraint at site. There was no space available to
construct a new plant of 150 mld capacity. Hence it was proposed to enhance the capacity of
treatment plant by retrofitting the various existing units of existing units by appropriate new
technology with minimum structural modifications.
The existing treatment plant was constructed in the year 2008 and had two streams A and B of
150 mld capacity respectively. It was proposed to increase the capacity of Stream B from 150
mld (6250 cum/hr) to 300 mld (12500 cum/hr) by using the plant augmentation technology. The
stream B consisted of 3 no of Clariflocculator and associated 20 no of Rapid sand gravity filter
beds.
Detailed investigation of treatment units and facilities was carried out to verify process,
hydraulic and structural parameters of the existing plant. From process point of view, there was
enough redundancy in the various existing units from application of intended unit processes. The
design of existing plant was found to be compatible for augmentation with minimum structural
modifications.
Since the existing inlet works consisting of a Receiving Chamber, Parshall Flume and a Flash
Mixer were in a dilapidated condition , it was discarded. A new Inlet works for capacity 300 mld
was proposed comprising of a Receiving Chamber, Flow measuring measure weirs and three no
of mechanical flash mixers.
Each of the three existing clariflocculator was proposed to be retrofitted with tube settlers to
enhance the capacity to 100 mld. The surface loading rate on tube settlers was 6000 lph/sqm. The
inherent deficiencies in the existing sand filter beds made the conversion into dual media filters a
complex process. Hence it was decided to construct new dual media filters of 150 mld capacity in
the little space that was available at site. Ten no of new high rate dual media ( Crushed coconut
shell and sand media) with a rate of filtration 10,000 lph/sqm were proposed to filter the
additional 150 mld water. The filters were based on Constant rate filtration with influent
splitting weirs and avoided the maintenance prone Rate Controllers. The balance flow of 150
mld was to be treated by existing filters.
Since the raw water was conveyed by gravity to the plant, there was no scope of manipulating the
headloss. The augmented plant was designed maintaining the same headloss as was in the
existing plant. NMMC constructed a new Pure Water Sump and Pump House to pump the
additional treated water to Master Balancing Reservoir.
The time required for completion of the job was one year. During performance trial in 2012, for
Raw water turbidity of 20 NTU, Clarified (settled) water turbidity varied in the range of 2-5
NTU. The filtered water turbidity was found to be in the range of 0.1 to 0.2 NTU. The cost of
this modification works was Rs.180 million (18 crores, 2010), which is 50% to 60% of the cost
of new plant of same capacity. These techniques have a huge potential for application in this
country. The resource crunch by default will be a single largest factor influencing in favor of
such cost effective and efficient techniques in the near future.
Schematic Flow Sheet of NMMC Augmentation
New and Old Inlet Works 
Retrofitting clarifier with tube settlers
Clarifier ready for commissioning 
New Duel Media filter house
Photographs of NMMC Plant
Courtesy: Navi Mumbai Municipal Corporation
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