International Journal of Engineering Trends and Technology (IJETT) – Volume3 Issue 4 Number2–Aug 2012
Design and testing of collection arrangement for
sewage from trains
S.Vanitha.
Department of Civil Engineering.
Bharath University.
ABSTRACT
As the characteristics of sewage generated at all places is varying and violating the standards, the
sewage should be properly collected, treated and disposed. All the trains are equipped with toilets and
wash basins. The sewage generated from these are not collected and treated. It is discharged as such on
railway tracks. The improper sewage disposal leads to unhygienic condition. This thesis is aimed at the
design and testing of collection arrangement for sewage from trains and processing in an eco-friendly
manner. The waste water is proposed to collect in a holding tank and the supernant liquid from the
holding tank is allowed to pass through the filter media in a filter tank. The filtered water is analyzed for
physical, chemical and biological characteristics. The remaining sludge in the holding tank is planned to
suck through a pumping mechanism. the pump is designed as per the specific weight and quantity (or)
flow of sewage. The collected sludge is planned to dispose in a septic unit.
INTRODUCTION
The world health organization (WHO) estimates that 80% of all deaths in developing countries is
related to water and excreta –related diseases. It is estimated that 12million people die annually; those at
highest risk being the poor and children. The disease for which causative organisms are associated with
faecal waste are virus, protozoa, bacteria, helminthes. The improper disposal of human excreta and
sewage is one of the major factors threatening the health and comfort of individuals in areas where
satisfactory sewerage systems are not available. this so because very large numbers of different diseaseproducing organisms can be found in the fecal discharges of ill and apparently healthy persons. Some of
the existing improved mechanisms for human waste management are septic tanks; biogas plants onsite,
public sewage systems and these systems not pollute the air, soil, or water sources.
Presently the sewage produced in trains is not collected properly. It is allowed to flow along the
tracks and railway stations, which cause nuisance to the public by producing a odor and creating ugly
scene. Also, the workers employed to maintain the railway track sections are affected both
physiologically and psychologically by this disposal technique.
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International Journal of Engineering Trends and Technology (IJETT) – Volume3 Issue 4 Number2–Aug 2012
Materials and Methodology
The thesis is aimed at developing new arrangement for the collection of sewage from the toilets
of trains and properly disposing it at an appropriate place to save the environment as well as the railway
workers.
Planning of the new arrangement:
The dimensions of the rolling stock were studied carefully and discussed with the railway
authorities about the clearance of distance between the bottom of the rolling stock and the rail.This is very
much needed to design the holding tank for the sewage to be collected from the toilet of a train.
The new collecting arrangement is planned as follows:
 The sewage including human excreta is to be collected in a holding tank.
 The excess water in the holding tank is allowed to pass on to the another tank acting as filter
tank.
 The filter tank filters the water and discharges the filtered water on to the ground along the track
and in stations.
 The solid waste settled in the holding tank is to be remove periodically at an interval of 12 hrs in
junctions.
Design of holding tank:
A holding tank is planned to collect the sewage from two toilets of a train. This tank is planned
underneath of the coach such that it is connected to the two toilets as shown in the figure using 100mm
diameter pipe. The dimensions available are 0.525m(dia) x0.6m(depth).Hence the holding tank may be
designed as a cylindrical one with inner dia as 0.5m and depth as 0.55m.the volume available will be
0.107 cubic meter.
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International Journal of Engineering Trends and Technology (IJETT) – Volume3 Issue 4 Number2–Aug 2012
Assuming 72 persons travelling in a coach, 36 will be using the two toilets. The flushing rate will
be approximately 5litres.
Volume of water used=36x5=180 liters.
The volume of water used is 0.180 cu.m is more than the cylindrical holding tank capacity which
is 0.107 cubic meter. After the holding tank becomes full the wastewater overflow and enter into the filter
unit comprises of sand and gravel.
Design of filter tank
The filter tank is also designed with the same dimensions of the holding tank. The two tanks are
connected by a 75mm diameter pipe as shown in the figure 3.1.It is planned to have two layers of filters
media, the bottom one is of well graded sand of thickness 200mm and the top one is of gravel of thickness
225mm.the sewage has to pass through this filter arrangement where in the suspended impurities will be
caught hold of and the free water will be flowing.
Fabrication of holding tank and the filter tank
The holding tank and the filter tank wearer fabricated using MS plate as per the dimensions
obtained in the design. They are depicted in figure.
Holding tank containing filter unit
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International Journal of Engineering Trends and Technology (IJETT) – Volume3 Issue 4 Number2–Aug 2012
Function of holding tank:
The solid particles coming to this tank settle down at the bottom of the tank which is ciollected by
outlet arrangement provided on sideways. The outlet is opened after connecting the flexible pipe,the
sludge is sucked by means of pumping mechanism.
Function of filter tank:
The filter tank functions as an attached growth process, in particular ,a non submerged attached
growth process. the filter tank consists of a water tight basin within inlet and outlet arrangement, a layer
of graded sand and layer with two porous plates, one over the gravel layer and other over sand layer.
The filter media consists of top layer of 0.20 in thickness of graded sand. The sand passing
through 1.18mm sieve and retained in 0.6mm sieve is selected, dried and used. the bottom layer is of
thickness 0.225m consisting of coarse aggregate with size less than 10mm.One porous plate made of mica
with holes5mm dia, covered with filter cloth is introduced in between sand layer and gravel layer in order
to retain the sand.
Top Distribution Plate
Another porous plate made of Ms Plate with 10mm dia holes is kept at a height of 7cm above the
graded sand layer. This plate receives the waste water suddenly discharged and distributes uniformly over
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International Journal of Engineering Trends and Technology (IJETT) – Volume3 Issue 4 Number2–Aug 2012
the sand layer. Otherwise gulling will take place on the top surface of graded sand due to sudden
discharge of waste water. The details are as shown in the figure .
Design of a pump
A pumping mechanism is required to remove the solids from the holding tank.Sewage handling
pump where flow by gravity is not possible, sewage pumps play an important role in the disposal of the
liquid- waste or sewage either direct to the rivers, sea, fields etc. or through the sewage treatment plants.
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International Journal of Engineering Trends and Technology (IJETT) – Volume3 Issue 4 Number2–Aug 2012
Non-clog pumps- general design features
Non-log (or clog less or solid handling or choke less) pumps are designed for thorough passage
of solid contents of the liquids. Such pumps are used for the following purposes.
1. Sewage and drainage dealings with heavily contaminated liquids
2. Industrial solid handling.
3. Dealing with fibrous materials like paper pulp.
These pumps are available in horizontal or vertical design and may be of submersible design also
non clog pumps are available with radial impellers up to capacities of 150 lps , beyond which mixed flow
type impellers are employed which have better efficiencies. casing is always radically split volute type.
Impellers of various shapes have been developed to deal with contaminated liquids of various grades such
as:
1. For unpurified municipal sewage containing large solids and sledges, for non- turbulent
conveyances, single vane closed type impeller are suitable.
Classification of non clog pumps
 Solid handling pumps.
 Submersible sewage pumps
 Sewage /drainage pumps
Sewage pumps
solid handling pumps ( type SH of M/s Kirloskar) for pumping abrasive or/ and corrosive
liquids with large particles sizes, are generally used for industrial duty slurries, sewage and waste water,
viscous and contaminated liquids containing fibrous materials, soft solids in suspension, sledges and
pulpy materials in sugar factories, chemical, fertilizer, paper and pulp etc. These have single end suction,
two vane enclosed radial inlet impellers with back vanes to maintain low stuffing-box pressure and
balancing of axial thrust. In these pumps more attention is paid to sturdiness of pump construction as they
have to handle solids of larger sizes. A very liberal bearing-span to impeller overhang ratio is provided to
ensure minimum shaft deflection and log life of gland pickings.
These pumps are available from 8 to 80m head range with discharge range of 5 to
200lps.Kirloskars type SH are solid handling pumps.
The pump is designed as per the quantity of sewage and specific wt of solid p[articles to be
handled.
Quantity of sewage = 5lit/person/day X 72
= 360lit/day = 0.360 m3/day
Non clog Kirloskars pump is suitable for sucking. Its rate of pumping is about 5-100 lit/min
having 2HP for sturdiness of pump.
Quantity of sewage is 360 liters so it takes 3-5 minutes to suck. Suction pipe is about 10cm.
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International Journal of Engineering Trends and Technology (IJETT) – Volume3 Issue 4 Number2–Aug 2012
assume, suction head Hs = 0.5m
Delivery Head Hd = 0.5m
Cleaning daily once is essential
The details of connections of pumping mechanism with the coach and the gravity line are as
shown as a layout.
Layout of connection and disposal mechanism
EXPERIMENTAL INVESTIGATION
EXPERIMENT-1
To study the level of treatment occurring in the filter tank, two types of experiments were
carried out. At the first instance, the entire filter tank is filled with well graded sand alone for at thickness
of 0.45m.The top is covered by a porous plate to prevent gulling. The supernatant liquid from holding
tank is allowed over the filter media. This takes 5 to 7 minutes to pass through the filter bed. The filtered
water is collected and tested for the three characteristics. Likewise the sample from wastewater allowed
for filtration is also analyzed for their characteristics. The result of tabulated in table
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International Journal of Engineering Trends and Technology (IJETT) – Volume3 Issue 4 Number2–Aug 2012
Details of waste water analyzed
Parameters
Before filtration
9.60
pH
2.21(2-20)
E.C
0.1mg/l
Dissolved oxygen
10.0
Turbidity
264mg/l
Chloride
264mg/l
COD
9763mg/l
BOD
34.4x108/1ml
Bacterial count
25503
MPN
After filtration
9.10
2.20
5mg/l
2.0
164mg/l
264mg/l
3000mg/l
50X102/1ml
166
EXPERIMENT-2
Instead of a single layer of well graded sand, it is planned to provide two layers of filter media;
the bottom layer consisting of gravel size <10mm for a thickness of 0.225, the top layer made of well
graded sand for a thickness of 0.20m.The two layers are separated by a porous plate covered with filter
cloth. The top of filter bed is again covered with a porous plate. The supernatant liquid is allowed to pass
through this filter medium which took 7 to 10 min. The waste water samples before and after filtration are
collected and analyzed for their characteristics. The results are tabulated.
Details of waste water
PARAMETERS
pH
E.C
Dissolved oxygen
Turbidity
Chloride
COD
BOD
Bacterial count
MPN
Hardness
Pottassium
BEFORE FILTRATION
9.60
2.21(2-20)
0.1mg/l
10.0
264mg/l
264mg/l
9763mg/l
34.5x108/1ml
25503
290mg/l
90mg/l
AFTER FILTRATION
9.10
2.20
3mg/l
4.0
200mg/l
264mg/l
4500mg/l
10x103/1ml
366
250mg/l
87mg/l
For testing purpose, the supernant liquid in septic tank is drawn and tested.
Holding tank provides as primary treatment necessary for the sewage collected and it removes
settle able solids and much of floating material. This also reduces the load on filter unit for further
treatment. In this tank, 50 -65 percent of suspended solids are reduced. Filter tank acting as secondary
treatment, serve as attached growth process, helps to remove microorganisms and remaining suspended
solids.
The results of the two experiments were compared and found that the results of experiments-1
were better than the results of experiments-2.In the particular more amount of pathogenic bacteria is
removed and DO value is increased.
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International Journal of Engineering Trends and Technology (IJETT) – Volume3 Issue 4 Number2–Aug 2012
Investigation for pathogenic bacteria
The supernant liquid from the septic tank is collected and characteristics will be observed as the
sewage contains microorganisms. The characteristics will be studied for coli form and total count bacteria
for before and after filtration. The sewage containing coli form and presence of coli form by gas
production as shown below.
MPN using Thomas equation
Coli form bacteria
Thomas equation can be used to estimate the MPN
MPN/100ml= no of positive tubesx100/ √ml of sample in negative tubex ml of sample in all tube.
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International Journal of Engineering Trends and Technology (IJETT) – Volume3 Issue 4 Number2–Aug 2012
no of positive tubes=5+5+5+4=19
Size of portion
1.0
0.1
0.01
0.001
Number positive
3
2
1
0
Number negative
2
3
4
5
 no of positive tubes (3+2+1+0)=6
 ml of sample in negative tubes=(2x1.0)+(3x0.1)+(4x0.01)+(5x0.001)
 =2.345
 ml of sample in tubes=(5x1.0)+(5x0.1)+(5x0.01)+((5x0.001)=5.55
 MPN/100ml=16x100/√2.345x5.55 =166/100ml
CONCLUSION
The sewage generated in trains is discharged in an unhygienic manner. Also it creates ugly scene
in railway stations and tracks. To overcome this drawback in an eco friendly manner, it is planned to
develop a collection arrangement through this thesis work. An attempt has been made to design, fabricate
and test the collection arrangement suitable for Indian railways.
By considering the existing coaches, a collection arrangement of two tanks is designed .One is
called as holding tank and other is a filter tank. The tank is interconnected to transfer the liquid portion
alone. The tanks are fabricated and tested by allowing supernatant liquid collected from septic tank.
Suitable filter media are constructed for filtration.
The waste water samples before and after filtration were collected and analyzed for their
characteristics. The results are very much encouraging .Hence this arrangement may be perfected and
implemented in Indian railways.
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