[Paper presented at All India Seminar on 'Innovative Applications for Low Cost Treatments of Water and Wastewater' on Feb.20-21, 2014 organised by Inst. of Engineers, Kolhapur Local Centre and Dept. of Technology, Shivaji University, Kolhapur]
Present
Status of Growing Cities
Due to rapid growth of urbanization, there is
unprecedented demand for new residential constructions. As a result, old
houses, vacant plots, open spaces in the
urban area are getting replaced by large building complexes and multistoried
buildings. Increase in population density due to these new buildings creates
necessity of facility centres and demand for low income servant community. This
community cannot afford to stay far away from work place and prefer to live in
temporary huts nearby. This leads to growth
of unauthorized slum areas.
Water is a basic need of human being. In urban
planning, water resource management assumes special importance as the
availability of water and
infrastructural facilities for protected water supply have to meet the ever
increasing demand of water. The existing water supply and under drainage
systems fall short of new enhanced
requirements. As a result, there is shortage of water supply in some areas
whereas excess wastewater in unsewered
area.
Water
Conservation Plan
Under this scenario, effective water conservation
and environmental protection in urban planning would need a three
pronged approach ie at individual household level, community level and
as a city service project .
- Water
Conservation at Individual Household level
Rain water harvesting, water conservation by
reducing use and wastage of water and recycling of wastewater for non potable
purposes by individual households can have great impact on reducing the
magnitude of the problem.
Rainwater is
purest form of natural water source and should be harvested and used for
potable purposes by storing it after simple filtration and disinfection
techniques. The excess rainwater should be used for recharging groundwater.
Water consumption can be minimized if we use it
carefully and prevent its wastage. Water saving plumbing fixtures and sensor
based taps can reduce water requirement considerably, however, the cost of such
gadgets are high and hence their use in individual houses is rare. Same is the
case with recycling of wastewater. In general the method of wastewater disposal
is septic tank followed by soakage pit and so called low cost methods of
treatment are not considered due to cost or space requirement in individual
houses.
Effective implementation of water conservation
measures depends heavily on public
awareness and education coupled with legal controls and incentive schemes for
water related taxes.
- Water
Conservation at Community Level
In case of large building complexes, hospitals,
hotels and business places, it is necessary to develop appropriate reward or punishment system for effective
water conservation.
Segregation & treatment of greywater and soil
waste provides effective and economical method of wastewater recycling. At
Walchand Institute of Technology, Solapur such system is successfully
implemented. The soil wastes from hostels are separately treated in small
digestors the supernatant from digestors is treated with grey water ( from wash
basins, bath and kitchen) in anerobic filter. The treated wastewater was used
for gardening reducing total water requirement.
In the city extension area, the housing colonies
have to keep some area vacant for public purpose. City authorities can enforce
the societies to use portion of this vacant land for wastewater reuse by
employing DEWATS and composting of solid wastes.
Legal enforcement of rain water harvesting, using
water saving fixtures like dual flush for closets, sensor based wash basins,
aerated flow shower heads, waterless urinals and constructing low cost
wastewater treatment and recycling is possible for new establishments. Green
rating as suggested by CII GRIHA star rating system may help in this case. Reduction in property tax and water related taxes as an incentive may also
give impetus to effective water conservation.
- Role
of Public local bodies
New
Avenues for Water Supply
- Direct
pipeline for potable water
In order to supply unpolluted water to urban areas,
direct pipeline from dam storage is
considered as better alternative than lifting the water from river. However, it is a long term project and the
cost of such scheme may become limiting factor. It is argued that such a system
will reduce importance of water quality preservation in river and would affect
rural population who have to depend on river water.
- Dual
reticulation system
Dual reticulation system as used widely in Australia
is based on the principle of providing separate pipe networks for potable water
and water for other non-potable uses. Such systems are high capital intensive
but prevent wastage of well treated potable quality water for non potable
purposes.
- 24x7
water supply
24x7 continuous water supply system can eliminate necessity of water storage for each
house, will prevent entry of contaminated water due to positive pressure and
would reduce the cost of water distribution network. The success of this system
depends on leakproof distribution and strict water metering system.
Present
status of water treatment plants
Design and
operation of water treatment plants in India have remained traditional with use
of conventional treatment units and operation by untrained personnel. Most of
the plants are quite old and have not been augmented due to lack of funds. Over
the years, the demand of water has increased significantly, but the plants are
being operated under overloaded condition resulting in unsatisfactory
performance. A fact-finding survey by NEERI1 revealed deteriorated
conditions of water treatment plants in India during 1972 and the conditions
have remained practically the same till now. Poor pre-treatment and
non-availability of skilled personnel for operating the plant make the
situation worse, resulting in large and unpredictable changes in treated water
quality.
The existing
water treatment plants can be upgraded by incorporating new technologies like,
tube settlers, multi-media filtration and electronic monitoring and control
equipments. In this process major infrastructural construction cost can be
saved. However, it is seen that, there is a tendency to scrap old plants and
erect new plants. Research and development work done in India for augmentation
of existing plants is not put into practice resulting in financial loss and
making the research effort a futile exercise.
Impact
of Enhanced Water Supply on Wastewater Collection System
It is observed that water supply enhancement
projects are sanctioned and implemented on priority. Such increase in water
supply leads to increase in wastewater flow which cannot be effectively
collected by existing city sewerage system leading to pollution of natural
drains (Nallahs) and storm water gutters.
Due to blockage by debris or due to unavailability of proper slope, these
gutters are often full with stagnant water creating health hazard and mosquito
breeding. In fact water supply and drainage projects must be implemented
simultaneously to avoid pollution due to excess wastewater generation.
Vacant plots, public open areas are often used for
dumping solid wastes by neighboring community. If there is stagnant water in
such areas, it also creates unattended pollution spots. Even though, there is
door to door garbage collection system and provision of public dustbins, the
solid wastes lying in open spaces and pools of stagnant polluted water remain
unattended.
Provision of proper under drainage system can give lasting
solution to this problem but augmentation of existing drainage schemes or
design of new systems require large
financial outlay and long time span for completion. It is seen that in majority
of cases, such schemes are stuck due to financial constraints and low priority
than water supply schemes. Hence sustainability of environmental quality in
growing urban area cannot be maintained within safe limits.
Under these circumstances, only option is to provide
effective short term measures to Short Term Measures to avoid environmental
pollution.
a) It is
essential to provide efficient sewage lifting system for reducing pollution due
to stagnant wastewater in open gutters and public places. Sewage carrying
tankers with vehicle mounted small capacity slurry pumps can be used to pump
such stagnant sullage water and discharge it in nearby manhole of existing under
drainage system atleast twice in a week.
This will prevent mosquito breeding and
reduce ground water pollution significantly.
b)
Provision of modified root zone cum percolating gravel beds along both the
edges of existing natural drains will partially treat incoming wastewater from
unsewered area and prevent entry of floating solids and garbage in nalla. This
will help in keeping the natural drains clean and under flowing condition.
Dnyandeep Foundation Initiatives
Internet is the modern,
effective yet very economical communication medium for educating masses,
providing latest technology information with multimedia content, get feedback
and video conferencing of all decision makers and stake holders concerning the
project life cycle. Dnyandeep Foundation has launched two websites ie www.envis.org
and www.green-tech.biz for creating awareness and education regarding
Environmental and Green Technology.
Now the foundation has
planned to develop environmental resource group and impart online education
courses in these fields. There shall be online discussion forum to promote
communication between architects, engineers and building professionals
interested in environmentally responsible design and construction.
Let us hope that we
shall be able to build strong active group of resource personnel for education
and planning of sustainable urban development projects.
