Utilisation of Sewage Sludge Ash in Construction materials

PROJECT GUIDE: Dr. T. MURALI KRISHNA

EXTERNAL GUIDE:Mr.R. RAMACHANDRAN

BY

M.ABILASH (11310103002)K.AJITH (11310103005)AR.SASANK (11310103006)MA.NETHAAJE (11310103029)

INTRODUCTION

Sewage Sludge is that obtained after the treatment of sewage from sewage treatment plant (STP)

The present scenario is that this treated sludge is used for land fills (open and closed), soil conditioner and natural fertilizer.

Most of the city and towns the sewage disposal is not proper, improper disposal of this treated sludge will cause environmental problems like,

Seepage of gray water into the ground water etc.,

OBJECTIVES

Effective management of the sludge is a

challenging problem . Main objective of our project is to

utilize the sewage sludge in making construction

materials by incinerating sludge

LITERATURE REVIEWSludge ash in clay bricks :

The appropriate percentage of ash content for producing quality brick was in the range of 20 to 40 %The optimum moisture content is in the range of 15 to 20%The molded mixture is fired at 1000 degree Celsius for 6 hours.

Sludge in concrete :

The chemical component of the incinerated ash of sewage sludge is close to the component of cement used in concrete.If we use small ratio of sewage sludge ash(SSA) we can produce good ordinary Portland cement (OPC).If we increase the ash content in the cement due to its porosity we can make pervious concrete.

METHODOLOGYFlowchart for Experimental Procedures for clay bricks

Dewatered Sewage Sludge

End product

105 oC Oven Dry Incinerate at 800 oC

Determine sludge and Ash Characteristics

Crushed Clay Prepare Brick Mixtures 0 % - 50 % Ash

Analyse:Specific Surface Area,Atterberg’s test,Compaction test

Vacuum out Air from the mix.Extruded into Standard ModesMaturated for 24 hrs then 103 oC oven dry

Fired at 950 o C, 1000 o C, 1050 o C

Building Brick Tests:Firing Shrinkage, Loss on Ignition, Water Absorption,Bulk Density, Compressive Strength

WORK DONE Collecting sewage sludge from STP

Testing the properties of dried sludge

Incinerating the dried sludge

Testing the properties of sewage sludge ash

Particle size distribution of sludge ash

Preparing the clay bricks

Ash in clay bricks

Ash in concrete

Ash in pavers blocks

COLLECTING SEWAGE SLUDGE FROM STP

Sewage sludge is collected from Koyambedu Sewage treatment plant.

The collected sludge is from the first drying bed of the STP.

The moisture content of the collected raw sludge is 5.27% so the sample is dried under the natural heat (sun light) for two days.

As the sample collected from STP is in the form of cakes is has bee pulverized to completely dry the sludge

PROPERTIES OF DRIED SLUDGE

No harmful emissions are identified since sludge is used for agricultural purpose as natural fertilizer.

But ,testing of raw sludge is necessary before incinerating the sludge.

Harmful emissions are found once the sludge is incinerated.

INCINERATING THE SLUDGE

Sludge has to be incinerated at an temperature of 850 to 900 degree Celsius, so there has to be a closed conduit.

This type of incinerators available only in industries

We incinerated our sewage sludge in bio-gas incinerator which can produce a maximum temperature of 1000 degree Celsius.

We made separate tray made of mild steel (MS) of size 6*2ft.

The efficiency of incinerator for our sludge is 70%

INCINERATOR INCINERATED ASH

PROPERTIES OF SLUDGE ASH

• The main aim of our project is to reduce the contamination made by the sewage sludge, so the sludge ash is tested for the presence of toxic elements

• We tested the sludge properties, the results shows the toxic elements are with in the limit

• The test results shows the presence of heavy metals which causes leaching effects are in the trace level

PARTICLE SIZE DISTRIBUTION

As the sludge collected from the STP is a mixture of sand particles with sludge, it has to be fine sieved.

Sieve used for particle size distribution

For Brick 0.850mm (Pass through) ASTM 20

For Concrete 0.212mm (Pass through) ASTM 70

PREPARING THE CLAY BRICKS

Weight of fresh Brick : 4.4kg Weight of a well dried brick (Nil moisture) : 3.4kg Water content : 4.4-3.4 = 1000gms = 1ltr Approximately 800ml water is used for a clay brick

PROPORTIONS

Percentage of

ashWeight of

MudWeight of ash

% grams grams30 2380 102040 2040 136050 1700 1700

CASTED SEWAGE SLUDGE ASH BRICK

FIRING OF CLAY BRICKS

TESTS ON FIRED CLAY BRICKSS.N

Ash % in brick

Weight of clayBrick(kg)

(a)

Weight of fired bricks(Kg

(b)

Loss on Ignition(Kg)(c)=(a)-(b)

Weight of water absorbed brick (Kg)(d)

Differenc in weight (kg)(e)=(d)-(b)

1 NIL 3.600 3.396 0.204 3.940 0.544

2 30 % 3.000 2.790 0.210 3.333 0.543

3 40% 2.810 2.572 0.238 3.442 0.870

4 50% 2.730 2.418 0.312 3.542 1.394

SLUDGE ASH IN CONCRETE

Properties of Sludge Ash:

Name of the Parameters Protocol Unit Result

Total Kjeldhal Nitrogen as N

14684 1999 (Reaff.2005) % 0.30

Phosphorus as P 14684 1999 (Reaff.2005) % 1.1

Potassium as K EPA 3050 B % 0.14Mercury as Hg EPA 1311 mg/kg BDL(DL:5.0)Cadmium as Cd EPA 3050 B % 0.27Arsenic as As EPA 3050 B mg/kg BDL(DL:5.0)Lead as Pb EPA 3050 B % 0.01Chromium as Cr EPA 3050 B % 0.005Nickel as Ni EPA 3050 B mg/kg 45.9Manganese as Mn EPA 3050 B % 0.043Copper as Cu EPA 3050 B % 0.177

Iron as Fe EPA 3050 B % 2.29

Calcium as Ca EPA 3050 B % 5.59

Properties of sludge:Name of the Parameters Protocol Unit Result

Moisture IS 2720 Part 2 1973 % 5.08Total Kjeldhal Nitrogen as N

14684 1999 (Reaff.2005) % 0.32

Phosphorus as P 14684 1998 (Reaff.2005) % 0.93

Potassium as K USEPA 3050 B % 0.83Cadmium as Cd USEPA 3050 B % 0.32Arsenic as As USEPA 3050 B % 0.003Lead as Pb USEPA 3050 B % 0.01Chromium as Cr USEPA 3050 B % 0.006Nickel as Ni USEPA 3050 B mg/kg 61.4Manganese as Mn USEPA 3050 B % 0.041Copper as Cu USEPA 3050 B % 0.23Iron as Fe USEPA 3050 B % 11.28Calcium as Ca USEPA 3050 B % 5.7

REACTION IN CEMENT AND ASH MORTARResults from FTIR

Ash % in concrete The presence of Calcium as Ca in sludge ash prompted

us to replace cement partially in concrete.

Grade of the concrete is M20

Water Cement ratio is 0.6

The proportion of ash added is 20%,30% and 40% to

the cement.

CASTED,ASH MIXED CONCRETE CUBES

COMPRESSIVE TEST

Sl.No

Grade of concrete

Percentage of ash

Compressive strength (KN/mm sq.)

1 M20 20 % 18.7

2 M20 30 % 16.6

3 M20 40 % 16.4

REACTION BETWEEN CEMENT AND ASH

S.No

Percentage Ash in Mortar

Calcium Silicate Hydrate(g/Kg)

Calcium Hydroxide

(g/Kg)

Ettringite

(g/Kg)

Mono Carbonate

(g/Kg)

1 NIL 18.68 2.0 11.34 25.852 20 % 6.32 0.67 14.58 24.633 30 % 5.10 0.54 16.77 23.454 40 % 6.96 0.76 15.12 22.81

IMPORTANCE OF HYDRATION

Calcium silicate hydrate, this is the main reaction product and is the main source of concrete strength.

Calcium hydroxide contributes slightly to the strength and impermeability of the paste, because it reduces the total pore volume by converting some of the liquid water into solid form.

Ettringite is formed in hydrated Portland cement system as a result of the reaction of calcium aluminate with calcium sulphate, both present in Portland cement

ASH IN PAVER BLOCKS

Mix Grade used for paver block is M40. Normal procedure of making paver blocks is adopted 80 mm zigzag blocks are casted. Cement in pavers are replaced by 20%,30% and 40% with

sludge ash.

PERVIOUS NATURE OF PAVER BLOCK

PASSIVATION The presence of nickel as Ni is 45.9 % in our

sludge ash.

Nickel can be used for handling elemental fluorine, owing to the formation of a passivation layer of nickel fluoride.

By devising some technique , the reinforcements inside the structures can be prevented against corrosion by using Nickel in sludge ash.

FeasibilityIncineration is a good process by which all toxicities can be eliminated. But by incineration the emission of toxic gases are at higher rate. These toxic gases can be decrease by using the following methods,

Closed chamber incineration . ESP (Electrostatic Precipitators) in incinerators.  

Conclusion

Ash in clay bricks: Loss on Ignition (LOI) is on higher side . so alternative procedure is needed to use sludge ash in clay brick.

Ash in Concrete: From sludge ash having smaller sized grains, denser concrete can be made, when cement is replaced.

Ash in paver blocks: Use of quarry dust and sludge ash made paver blocks pervious attaining same properties as normal blocks.

THANK YOU