Welcome back, today we will discuss little bit about Wastewater Management in Developing
Urban Environments, especially Indian scenario we'll discuss about, okay.
As all of you know wastewater treatment is one of the most neglected services among all
urban services, many cities with a population of more than 10 lakhs have some sort of collection
systems catering to only part of the population.
Coastal cities and cities located on the banks of rivers discharge the untreated or partially
treated wastewater into the nearby water bodies.
Many places wastewater treatment is limited to septic tanks.
Uncontrolled and unsupervised use of septic tanks has led to severe groundwater contamination,
and we can see the wastewater managements scenario in India in this slides, this
is 2011 data, in 2011 around 40,000 million liters of water per day is generated in domestic
sector, whereas around 15,000 plus in industrial sector, most of the time we think that industries
are the most polluting sources, but the truth is the other way around 60 percentage of the
industrial wastewater are getting completely treated as per the norms only 40 percentage
is getting discharged and treated in this, the small and micro level industries.
But when it comes to the domestic wastewater you can see here, okay, this is the domestic
wastewater, okay, generated in Urban India and in Rural India, Urban India around 40,000
million liters per day is generated, and in Rural India around 77,000 plus is getting
generated, and in Urban India and the treatment is, treatment capacity is only around 11,000
plus, and Rural India it is only 772, you can see that, okay, we're only very, very
little part of the wastewater is getting treated, I have summarized here only 26 percentage
of the domestic wastewater and 60 percentage of the industrial wastewater is getting treated
in India.
And 423 class one cities treat around 29 percentage and 499 class two cities around 4% of domestic
wastewater is getting treated, the major reason is inadequate infrastructure.
So now we know that lot of emphasis is given on Swatch Bharat and correct cleaning and
wastewater management, wastewater treatment etcetera, so if you okay go or if you create
much more infrastructure you see the condition here treated wastewater is around 11,788 million
liters per day and untreated is around 27,808 million liters per day, but in 2035 if you
see definitely the treated waste water quantity will be increasing significantly, it may go
up to 65,2280 million liters per day, but you can see the untreated wastewater quantities
also increasing, it become around 28,269, the reason is okay, though infrastructure
is developing, okay, but it is not able to meet the quantity of wastewater getting generated
in India, as the population is growing the amount will be getting, amount getting generated
will be increasing significantly, so this is the wastewater generation projected for
the year 2035, okay, this is rural and poor around 61,000 plus and Urban India around
93,000 plus, and rural treatment will be only 4,000 something and Urban India it will be
around 65,228 so that's why though the infrastructure develops that pace at which it is developing,
okay, the coverage or the untreated wastewater getting into our rivers and water sources
will be increasing day by day.
So this is, okay, this shows the availability and type of toilets as rather 2011 census,
okay, Rural India in 2011 open defecation was very prevalent around 67.3 percentage,
now it has reduced significantly because of the Swatch Bharat campaign and all the things
and Urban India also was not that good around 12.6 percentage was practicing open defecation,
and sewerage facilities available only 32.7 percentage in the Urban India and around 38.2
percentage is still depending upon a septic tanks and you can see that so many other options
are also available or practiced in the Urban India, so if you see all over India, okay,
open defecation is still there, okay, but if you look into the sewerage coverage it
is only 11.9 or around 12 percentage, and septic tank coverage is around 22.2 percentage.
So when we talk about the wastewater management we have to realize the ground reality, okay,
most of the time when we talk about the wastewater treatment, okay we think about a centralized
treatment system and all the things, but that can be achieved or that can happen only the
places where there is a sewerage coverage, so when the wastewater is not treated and
getting into the rivers, what will happen?
All our rivers are highly populated, okay, so you see anywhere and everywhere we go the
rivers are like this, okay, so much of forms and other things, and all the
garbage and other things are getting discharged into the rivers, and okay, lot of okay wheat
form growth inside the river and that is reducing the carrying capacity of the river and affecting
the flora and fauna inside the river, and the DO level are coming down and all the things,
okay, so this is the status of the river and the reason is untreated wastewater getting
into the rivers, okay, large quantities of untreated wastewater.
As we have discussed in the earlier lecture or these rivers the waste load or pollution
load is much, much, much higher than the carrying capacity of the river, the river is not able
to take care of any of these pollutants so okay, why should
we bother about the pollution?
Economic losses due to improper sanitation is huge, okay, around 73 million working days
are lost due to water bond diseases, okay, we have seen what is water bond diseases and
around, okay, $600 million are lost because of this one per year, and around 6.4 percentage
of Indian GDP's lost due to improper sanitation and economic loss in tourism industry in India
is around 448 million US dollars per year, because people wanted to go to a very clean
and pristine area for tourism, not a river like this, okay where it is highly contaminated
with all domestic and industrial waste and solid waste etcetera, so definitely if you
are not doing the waste management properly it is having a significant economic loss.
So now we'll see what is the present sanitation model okay, so this is what is happening,
okay, we have cities, okay, the food is coming from the agriculture fields, okay, agriculture
fields we are using the chemical fertilizers, and the food is supplied to the city and water
is coming from the river and river water may not be sufficient on many places we are taking
lot of ground water to supply the water to the city, and the treated wastewater, wastewater
whatever is generated okay, the black water that means the wastewater coming from the
toilets and the gray water, wastewater coming from bathrooms and washbasins and all, okay,
all the things are getting mixed up and going to the wastewater treatment plant, here you
can see that only a part is going to the wastewater treatment plant, we have seen that around
26 percentage or 28 percentage, and remaining is going directly to the rivers, okay, without
any treatment, and in the wastewater treatment also okay we are not bothered much about the
nutrient removal and all, so partially treated effluent is again getting back to the rivers,
and wastewater treatment plants will be generating sludge, the sludge is okay dumped in the lands
fills around 95 percentage of the sludge is getting dumped in the landfills, not landfills
only just okay disposed it off and only less than 2 percentage is going for composting,
okay.
And around 3 percentage is used directly as soil conditioner and whatever is used for
composting is going for the agricultural fields and oil, okay, so this is what is happening,
so all these things the chemicals, okay, the wastewater untreated, partially treated everything
is going to the river, so and this river water is being used by the cities which is staying
in the downstream of the river, so indirectly all of us are drinking the other persons wastewater,
okay, without much hesitation, so when we talk about wastewater can be treated and reused
for various purposes, people have the psychological inhibition, but every day we are doing that
without our knowledge, so okay, and today the waste water management is, okay, based
upon centralized wastewater treatment systems, that means the water or the wastewater generated
in the city is collected through pipeline, we call it as sewers, the sewer lines so if
you want to carry the waste through the sewer we have to have large quantity of water, because
otherwise the solid will be getting deposited there, so request expensive piped infrastructure
and treatment facilities and encourage water consumption, because the pipe should have
the minimum velocity, otherwise all the solid will be getting accumulated there and it will
be clogging the pipeline so okay centralized systems will be centralized waste on the treatment
systems, encourage water consumption and most of our
treatment systems does not reduce nutrient pollution because the treatment systems are
not designed for that one, so pollutes the earth and water bodies with the concept solution
to pollution is dilution, but our rivers are not having much water, so it is that and air
water bodies are getting contaminated, so it's not sustainable.
So now there is a paradigm shift in the recent past, in the past wastewater was a problem,
or it is considered as the problem, now it is considered as a resource that means many
places zero liquid discharge is being practiced that means whatever the wastewater generated
you treat it to the required level for the specified beneficial use and recycle okay,
within the community or within the facility completely, so that is known as zero liquid
discharge that means no liquid is getting discharged.
So examples are many, new water scheme is Singapore, because Singapore and there water
is getting treated and okay putting it in the rivers and lakes and they're reusing it,
treated domestic wastewater for industrial use, even in Chennai many industries are practicing
this one, zero discharge norms for major industries, and it is coming in the big way wherever water
source is there, and recycle water for domestic use may not be for drinking purpose for all
other secondary uses like toilet flushing, gardening, okay, cleaning etcetera, treated
wastewater for groundwater recharge and irrigation, here we have to be extremely careful, if you
want to use the treated wastewater for groundwater recharge, the quality of the treated wastewater
should be as good as the drinking water, otherwise what happens the groundwater will be getting
contaminated, once the groundwater get contaminated treating that one will be very, very difficult.
So when we talk about wastewater reuse the treated wastewater can be reuse for multiple
purposes, okay, like recreational and environmental uses, okay we can do lakes and ponds, okay,
to renovating that one we can use them treated wastewater properly treated wastewater, otherwise
it will be leading to much more problem.
Marsh enhancement, stream flow augmentation because if the rivers are not having the environmental
flow so how can we get the water, okay, you treat all the wastewater to the required quality
and putting back to the river so that the stream flow augmentation can happen, then
it can be used for fisheries and for wetlands.
Then when we come to the wastewater management systems, okay, usually that can be classified
them into three categories one is centralized systems, next one is decentralized systems,
and onsite systems, so when we talk about a city or a town, okay, if you want to achieve
100% wastewater management, okay, it should be a combination of centralized systems, decentralized
systems and onsite treatment systems.
Now we'll see what are these centralized systems and decentralized systems, so centralized
wastewater treatment system means, okay, all the wastewater generated into city is or city
or town is collected through pipelines, okay, this pipelines maybe 100 of kilometer long,
and all the wastewater is getting collected and take it to the low laying area, okay,
in the outskirts of the city wherever you have enough land treated there and discharge
it that is what the centralized treatment system, this is one of the towns in Tamil
Nadu, okay, Trichy, so here you can see that okay this is an example of centralized sewage
treatment system, so these are the pipelines okay you can see that all the sewer lines
and all the water, wastewater is getting collected and okay it is bought two area here, okay,
and here it is getting treated far away from the city, but here we have problems, okay,
some areas which are low laying compared to the major pipeline, okay, it is very difficult
to connect to the existing sewer systems, the reason is if you want to get connected,
okay, we have to have the plumbing stations and all so the operation and maintenance cost
of such systems will be, okay, huge, so it is advisable to have centralized system and
whichever is not, whichever area is not possible to connect to the centralized treatment system,
centralized sewer system can have decentralized wastewater treatment system, that means for
that location you provide a small treatment, and if you have some isolated houses and all,
providing the sewer network will be very, very costly, in such cases you can go for
onsite treatment system, that means only for a single house or a cluster of houses you
can have a very small treatment system.
So this is centralized wastewater treatment system that means any wastewater is getting
collected through the sewer network and transported to a faraway place and getting treated and
discharge there, okay.
In the decentralized wastewater management system, okay, what we are doing is where all
the wastewater is generated in that area itself it is getting collected and treating, okay,
this is a housing colony, some individual residences are there, some educational institute
is there, everything is very closed by, so what you do you collect all this wastewater
and treat it in a wastewater treatment plant here, okay, so this is an example of decentralized
wastewater treatment system, so if you are thinking of reusing the treated wastewater
it is always economical to go for decentralized wastewater treatment systems, because centralized
wastewater treatment system we are taking all the wastewater, okay, to a faraway place
than where it is getting generated.
Then if you want to reuse it you have to permit back to the place where it is regret, so that
piping cost, plumbing cost everything will be, okay, very high, here what is happening
is we are treating the wastewater wherever it is getting generated, so reuse will be
much, much easier, okay.
So onsite treatment systems means for individual houses or a cluster of houses we're providing
the wastewater treatment systems, and in India okay the onsite treatment system mostly consists
of septic tank, so this scenes are very common in India, okay, this is a septic tank and
this is the gas wind pipe we can see that one, okay, it is an underground, okay, water
type tank, okay, only the flowing will be coming out, okay, and you can see, okay, this
is a clock septic tank and this is the honey circle which comes and sucks the sludge from
the or septage from the septic tank, okay, and okay many places this septage is going
okay, getting discharged into okay wherever they see the place, okay, so those things
can create much problem.
And if you want to see a proper septic tank, okay, this is a cross section of a proper
septic tank, usually it will be having two chambers or some cases three chambers, and
it should be a water type tank and whatever the effluent coming out of the septic tank
should be sent to a drain field, okay, so that because in the septic tank around 50
to 60 percentage of organic matter involve is taking place, and the last number of pathogens
will be coming out in the septic tank fluid, so if you just discharged it in the open drains
and all, okay, there will be significant groundwater contamination, so here what we are doing is
we are spreading it into a large area in the soil, so soil acts as the treatment media
and the waste is getting treated, so but because of the land constrains and all the things
many places this drain field is not existing at all, okay, so a properly descends drain
field you can see like this house, septic tank and a drain field, but many places this
drain field is not existing, so either the effluent is going to the drainage or it is
just entering into sock pit and, okay from there it is infiltrating into the ground water,
if the ground water table is very high.
So problems of improper wastewater management, we have already discussed, contamination of
surface water sources most of the rivers in India, okay, we can talk about Ganga, Yamuna,
Adyar, Coovum, any river you take it, okay, many things are getting contaminated and if
you are not descending and operating the onsite treatment system properly, again contamination
of groundwater can happen, okay, I'll talk to you about some example from Kerala, so
this is the case study from Kerala, we all know that Kerala, okay, open defecation is
almost nil, and all social development indices are very good, okay, and okay they have very
nice rivers and all the things, and mostly the environment is clean and all the things,
but what is the status of the groundwater, so we have done a study just
to monitor the water quality, surface on groundwater quality in for districts of Kerala, just to
find out how the quality is.
So we have conducted, okay collected samples, okay around 309 samples, okay, from open wells,
bore wells, and tap water, so what I wanted to show you is, okay, here the number of open
wells, percentage of open wells, bore wells, and tap water I cashed on, so you can see
that bacteriological quality in open wells, and
all the four blocks during monsoon you can see that open wells around 68 percentage of
the wells are having fecal contamination, and only 32 percentage wells are free from
that one, this is after monsoon, okay, around 58 percentage and 42 percentage, okay, so
what I'm trying to tell is even if you have the onsite sanitation systems and all, if
you are not managing it properly, okay, your groundwater will be getting contaminated significantly,
and this is the bore well in all the four blocks, okay, almost all the bore wells are
okay contaminated, okay, this is after post monsoon, okay we usually think that okay open
wells are prawned to contamination, okay, and bore wells are not that prawned to contamination,
but why it is happening, because the groundwater table is very high, the things are getting
into the groundwater and open well okay, okay many times they do the disinfection in the
well itself, so many wells are getting cleaned, but bore well, since the bore is many times
bore well is dug in the open well, so what is happening is the chlorination is not affective,
and the aquifers are getting interconnected, so the bore well is contaminated and that
disinfection is not happening that's why the bore well is showing much more contamination,
and tap water also we can see that it is getting contaminated or around
57 percentage of the tap water is also contaminated.
What I am trying to tell is even if you have toilets, if you are not managing the waste
properly you can have severe ground water contamination problem.
So now, okay so we have seen the scenario wastewater management in India, now we look
into what are the wastewater treatment systems or how can we treat the wastewater, so usually
the wastewater system generally comprises of 3 parts, we have a primary treatment, a
secondary treatment, and the tertiary treatment, the objective of the primary treatment is
to remove suspended, easily settleable and floating material, and secondary treatment
are provided to remove colloidal and dissolved organic matter, and tertiary treatment systems
are provided for polishing the secondary treated effluent to meet the reuse or discharge requirements,
okay, because secondary will be removing most of the organic matter, but pathogens and some
other contaminants and nutrients maybe present, so if you want to remove that one we have
to for tertiary treatment, so this shows wastewater is entering, first you have screens, grit
chamber, primary sedimentation tank, this is optional,
some treatment system doesn't need this one, then you have biological wastewater treatment
system, solid liquid separation system, then disinfection.
And the first thing, okay, this yellow color shows the treatment units use for removal
of suspended solids, green systems removal of biodegradable organic matter, and blue
for destruction of bacteria, and after that one it is discharge to rivers, but if you
want to reuse the thing, okay we have to give further treatment, so we have to, okay so
recycle and treatment, raw wastewater, raw wastewater treatment, okay, so we can treat
it in the better way and recycle within the system.
So what are the wastewater treatment processes and technology, there is no that of technologies
we have N number of technologies available for the treatment of wastewater, okay, if
you are waste stabilization ponds, constructed wetlands, these are engineer, natural systems,
cost effective, okay, and you don't need any electricity or mechanical devices, then USAB
upflow anaerobic sludge blanket reactor, moving bed biofilm reactor, activated sludge process,
extended aeration process, sequencing batch reactor, membrane bioreactor like that we
have all type of technologies available depending upon the treatment quality requirement and
your space availability and all you can select appropriate treatment technologies, okay.
And in wastewater especially for domestic wastewater most of the time we go for biological
process, the reason is the wastewater will be containing lot of suspended, colloidal
and dissolve organic matter which are highly biodegradable, so instead of going for chemical
processes we usually adopt biological process.
In aerobic process what happen, your organic matter in cosines of oxygen, bacteria or other
microorganisms, okay convert organic matter to carbon-dioxide, ammonia, and end products,
okay, some energy also will be generated, this energy will be utilized for the synthesis
of new cells, okay, the new cells synthesis like this organic matter, oxygen, bacteria,
that energy is generated and it is giving new cells, and some days what will happen,
if the organic matter content is less, the microorganism will use the existing micros,
okay for and they will get the energy.
And low cost options as I told okay you have oxidation pond, aerated lagoon, anaerobic
ponds, facultative ponds, facultative lagoons, constructed wetlands, and this is a single
oxidation pond, okay here you can see that a symbiotic action of algae and bacteria are
happening and as a result the treatment is happening, that is what is
happening in oxidation pond, and this is a constructed wet land, here okay you have water
type tank and you'll be having plants and the metrics on which the microorganisms also
will be there, so you have a combination of physical, chemical and biological action taking
place and you'll be getting that treated wastewater.
And tertiary treatment as I explained already, okay you can based upon that you use, the
treated wastewater use you can select your tertiary treatment either you can go for coagulation
flocculation or other process, most of the time for toilet flushing or other secondary
uses the expected quality of tertiary treated water is BOD less than 10, suspended solid
is less than 5, phosphate around 0.5, MPN less than 10 milligram per liter, and tertiary
treatment can be nutrient removal, phosphate removal, okay,
chlorination, carbon adsorption or dual media filter, ultra filtration or even you can go
for reverse osmosis and disinfection, okay.
So what is the present scenario?
Wherever wastewater is collected, mostly treatment plants are not there, places where treatment
plants exist, enough wastewater is not collected, wholesome approach is missing in many places,
okay, but now cities are coming up with a city sanitation plans, most of the time the
funds are provided for only asset creation, operation and maintenance is not available.
So what is the way forward and integrated approaches needed, combination of centralized,
decentralized and onsite treatment systems, recycling and reuse, it has to be practiced,
combination of technologies according to the requirement, then we have to give tertiary
treatment also, policy changes to make the system sustainable, is essential proper enforcement,
and capacity building is also needed.