Incinerated Hospital Waste Using Cement Biology Essay




Solidification/Stabilization of

Incinerated Hospital Waste Using Cement,

Bentonite and Rice Husk Ash

Submitted in Partial Fulfilment of the Requirements for the

Award of the Degree of

Master of Technology


Civil Engineering

With specialization in

Environmental Engineering



(Roll No. 6004206013)

Under the Guidance of

Dr. S. M. Ali Jawaid

Associate Professor,

Civil Engineering Department,

Madan Mohan Malaviya Engineering College,

Gorakhpur - 273 010 (Uttar Pradesh)

Civil Engineering Department

Madan Mohan Malaviya Engineering College

Gorakhpur - 273 010 (Uttar Pradesh)

(An Autonomous College of Gautam Buddh Technical University,

Lucknow, Uttar Pradesh)

December, 2012


This is to certify that the work which is being presented in the Dissertation entitled

"Solidification/Stabilization of Incinerated Hospital waste using Cement, Bentonite and Rice

husk ash" in partial fulfillment of the requirement for the award of the Degree of Master of

Technology and is submitted in the Civil Engineering Department of Madan Mohan

Malaviya Engineering College, Gorakhpur - 273 010 (Uttar Pradesh) is an authentic record of

my own work carried out during a period from March 2012 to September 2012 under the

supervision of Dr. S. M. Ali Jawaid, Associate Professor, Civil Engineering Department of

Madan Mohan Malaviya Engineering College, Gorakhpur.

The matter presented in this report has not been submitted by me for the award of any other

degree of this or any other Institute/University.

Date: (Urmila Pal)

This is to certify that the above statement made by the candidate is correct to the best of my


Date: (Dr. S. M. Ali Jawaid)



The Dissertation Viva-voce Examination of Urmila Pal, M. Tech. Student has been held


Signature of Supervisor(s) Signature of HOD Signature of External Examiner

Madan Mohan Malaviya Engineering College,

Gorakhpur – 273 010 (Uttar Pradesh)


It is indeed a great pleasure to express my sincere thanks to my Supervisor Dr. S. M. Ali Jawaid,

Associate Professor, Civil Engineering Department, Madan Mohan Malaviya Engineering

College, Gorakhpur for his continuous support in this Dissertation. He was always there to

listen and to give advice. He showed me different ways to approach a research problem and

the need to be persistent to accomplish any goal. He taught me how to write academic paper,

had confidence in me when I doubted myself, and brought out the good ideas in me. He was

always there to meet and talk about my ideas, to proofread and mark up my paper, and to ask

me good questions to help me think through my problems. Without his encouragement and

constant guidance, I could not have finished this work.

Dr. J. P Saini, Principal, and Shri Ram Dular, Head, Civil Engineering Department, Madan

Mohan Malaviya Engineering College, Gorakhpur really deserves my heartiest honor for

providing me all the administrative support.

I would like to extend my deep sense of gratitude towards the Dr. Rakesh Kumar Shukla, Dr.

Sriram, Dr. Govind Pandey and other faculty members of civil Engineering department,

Madan Mohan Malaviya Engineering College, Gorakhpur for their co-operation.

Special thanks to Mr. Satayanarayan (Ph.D. Student, CED, IIT Roorkee) and my friends Mrs

Yaman Khan Yusuf Zai, Mrs Richa Pandey, Shri Arun Kumar Gupta, and Shri Varun

Bhardwaj for sharing their thoughts and also providing me a conductive environment for the


Last, but not least, I thank my parents, for giving me life in the first place, for educating me

with aspects from both arts and sciences, for unconditional support and encouragement to

pursue my interests. I dedicate this work to my parents who will feel very proud of me. They

deserve real credit for getting me this far, and no words can ever repay for them.

Date: (Urmila Pal)



Today human beings are most successful in science and technology but seem to be very

helpless as far as controlling the decay and preserving their own environment. Environmental

conservation and preservation have taken on great importance in our society in recent years.

Deep changes are taking place in our ways of living and of working. Among these changes

resource conservation and recycling of waste have become one of the principal issues.

The recycling or reuse of any waste residue in civil engineering application has undergone

considerable development over a very long time. In the most recent years, several researchers

have studied the possibility of using solid waste in road engineering and quickly it leads to

hot issue. It is for two major reasons-

 Lacking of natural resources such as rock, sand etc.

 Waste is a kind of resource and can be used as raw materials into many projects

Any waste whether be solid or liquid and any intermediate product generated

during treatment, diagnosis or immunisation of human being or animal, is called

biomedical waste. Incinerated hospital waste (IHW) is the by-product produced

during the combustion of hospital refuse or biomedical waste in combustor facilities.

These waste produced in the course of health care activities carries a higher potential

of infection and injury than any other type of waste.

This study is an attempt to evaluate the application of incinerated hospital wastes in

geotechnical engineering applications. Optimum IHW content to be mixed with soil was

evaluated by conducting Proctor’s Compaction Test. It is found that 9% of IHW is the

optimum binder content. Lechate studies were also carried out and it confirms high

concentration of toxic / heavy metals in soil + IHW mix. Solidification / encapsulation

studies were carried out using three different solidifying agents such as Bentonite, Rice Husk

Ash and cement. It is found that 9% of cement, 12% bentonite as well as 6% RHA are the

optimum binder content. However, the lechate studies suggested that the Cement is the best

binder for the solidification/ stabilization of the soil 9% IHW mix.



Chapter Page No.

Candidate’s Declaration i

Acknowledgement ii

Abstract iii

List of Figures vi

List of Tables vii

List of Abbreviations viii

Chapter 1: Introduction 1-2

1.1 General

Chapter 2: Literature Review 3-20

2.1 Management of Health Care Waste 3

2.1.1 Health care waste management issues 4

2.1.2 Current Issues in Management of Health Care Waste 5

2.1.3 Environmental Concern 6

2.1.4 Biomedical waste management process 7

2.2 Treatment process 8-11

2.2.1 Autoclave Treatment 8

2.2.2 Hydroclave Treatment 9

2.2.3 Microwave Treatment 9

2.2.4 Chemical Disinfecting 9

2.2.5 Sanitary and Secured Land filling 10-11

2.2.5 Incineration 11

2.3 Toxicity of Biomedical Waste 12

2.3.1 Heavy Metals 13

2.4 Past Studies 13-14

2.5 Solidification/Stabilization Process 15-17

2.5.1 Mechanisms of solidification/stabilization 17

2.5.2 Leaching Test methods 19-20


Chapter 3: Experimental Programs 21-27

3.1 Objectives 21

3.2 Materials used 21

3.2.1 Soil 22

3.2.2 Incinerated Hospital Waste 23-24

3.3 Binders 24-26

3.3.1 Cement 24-25

3.3.2 Rice husk ash 25

3.3.3 Bentonite 25-26

3.4 Testing 26-27

Chapter 4: Results & Discussion 28-36

4.1 Soil Improvement Using Incinerated Hospital Waste (IHW) 28

4.2 Leachate properties of solidified sample 29

4.3 Encapsulation/Solidification/Stabilization 29

4.3.1 Solidification/Encapsulation using Cement 29

4.3.2 Solidification/Encapsulation using Rice Husk Ash 30-31

4.3.3 Solidification using Bentonite 31

4.4 Leachate properties of solidified/Encapsulate soil + IHW mix 32-33

4.5 Study of Scanning Electron Microscopy Imageries 34-36

Chapter 5: Conclusion And Future Scope 37-38

5.1 Conclusion 37

5.2 Future Scope 38

Author’s References 39-41



Figure No. Caption page no

Fig. 2.1 Biohazard Symbol 6

Fig 3.1 Grain Size Distribution Curve for Soil 22

Fig 3.2 Soil Used in Stabilization/Solidification 22

Fig 3.3 Filtered Incinerated Hospital Waste for 23

Engineering Properties Testing

Fig 3.4 Grain Size Distribution Curve for IHW 24

Fig 3.5 Leaching Test setup after Shaw et al. (2003) 27

Fig. 4.1 Variation of moisture content and dry 28

density with IHW Content (%)

Fig. 4.2 Variation of density and moisture content 30

with % cement Content

Fig. 4.3 Variation of density and moisture content 31

with % RHA Content

Fig. 4.4 Variation of density and moisture content 31

with % bentonite content

Fig. 4.5 comparison of MDD with various percentages of binders 32



Table No. Caption Page No

Table 3.1 Engineering properties of soil 21

Table 3.2 Engineering properties of IHW 23

Table 3.3 Chemical composition of RHA 25

Table 4.1 Concentration of heavy metals present in 29

the leachate of Soil + IHW sample

Table 4.2 Concentration of heavy metals present in 33

the leachate of soil + IHW+ Bentonite sample

Table 4.3 Concentration of heavy metals present in the 33

leachate of soil + IHW+ RHA sample

Table 4.4 Concentration of heavy metals present in the 34

leachate of soil + IHW+ Cement content



IHW Incinerated Hospital Waste

MDD Maximum Dry Density

OMC Optimum Moisture Content

HSWIA Hospital Solid Waste Incinerated Ash

GSA Grain Size Analysis

RHA Rice Husk Ash


Chapter – 1


1.1 General

Biomedical or hospital wastes are defined as waste that is generated during the diagnosis,

treatment or immunization of human beings or animals, or in research activities pertaining

thereto, or in the production of biological. Biomedical waste generated in the hospital falls

under two categories - Non-hazardous and Bio hazardous.

Non - Hazardous wastes are non-infected plastic, cardboard, packaging material, paper etc.

Bio – hazardous- it divides into two types-

 Infectious waste- sharps, non-sharps, plastics disposables, liquid waste, etc.

 Non-infectious waste, radioactive waste, cytotoxic waste and discarded glass.

1.2 Classification of hospital waste

 General waste: Largely composed of domestic or house hold type waste. It is nonhazardous

to human beings, e.g. kitchen waste, packaging material, paper, wrappers,

and plastics.

 Pathological waste: Consists of tissue, organ, body part, human foetuses, blood and

body fluid. It is hazardous waste.

 Infectious waste: The wastes which contain pathogens in sufficient concentration or

quantity that could cause diseases. It is hazardous e.g. culture and stocks of infectious

agents from laboratories, waste from surgery, waste originating from infectious


 Sharps: Waste materials which could cause the person handling it, a cut or puncture

of skin e.g. needles, broken glass, saws, nail, blades, and scalpels.

 Pharmaceutical waste: This includes pharmaceutical products, drugs, and chemicals

that have been returned from wards, have been spilled, are outdated, or contaminated.

 Chemical waste: This comprises discarded solid, liquid and gaseous chemicals e.g.

cleaning, housekeeping, and disinfecting product.

 Radioactive waste: It includes solid, liquid, and gaseous waste that is contaminated

with radionuclide generated from in-vitro analysis of body tissue and fluid, in-vivo

body organ imaging and tumour localization and therapeutic procedures.


In India, the rate of generation of hospital waste is estimated to be 1.59 to 2.2 kg/day/bed and

out of which 10-15% is found to be bio-medical waste. If this 10-15% hazardous waste are

mixed with whole waste than 100% waste will become harmful. This is a huge amount

therefore; it required a proper management and treatment. Incineration is a treatment process,

which reduce the amount of hazardous waste. But million tons of incineration ash as

byproduct also contributes to environmental pollution so it also required a proper and

effective disposal.

Chapter – 2

Literature Review

2.1. Management of HealthCare Waste

Hospital waste is a heterogeneous waste mixture and it is a difficult task to manage it. A

proper management system may solve this problem and reduced its dimensions substantially.

So it is essential to take a glance at the management issues.

2.1.1. Health care waste management issues

The management principles are based on the following aspects

 A major issue related to current Bio-Medical waste management in many hospitals is

that the implementation of Bio-Waste regulation is unsatisfactory as some hospitals

are disposing of waste in a haphazard, improper and indiscriminate manner.

 Lack of segregation practices, results in mixing of hospital wastes with general

wastemaking the whole waste stream hazardous. Inappropriate segregation ultimately

results in an incorrect method of waste disposal.

 Bio-Medical waste scattered in and around hospitals invites flies, insects, rodents, cats

and dogs that are responsible for spread of communicable diseases like plague and


 Usage of same wheelbarrow for transportation of all categories of waste is also a

cause of infection spreading. Most of the times there is no monitoring of trolley

routes, resulting in trolley movement around patient care units posing a serious health


 Bio-Medical waste if not handled properly and within the stipulated time

-period could strike in the form of fatal infections.

 Lack of even basic awareness among hospital personnel regarding safe disposal of

Bio-Medical waste.

 Appropriate organization and management.

2.1.2. Current Issues in Management of Health Care Waste

There are two main issues at present:

 The recent legislation by the Govt. of India.

 Implementation of the same at individual health care establishment’s level as well

as whole town / city level.


The recent legislation has fulfilled a long standing necessity. Now this sector has got clear cut

guidelines which should be able to initiate a uniform standard of practice throughout the


2.1.3. Environmental Concern

The following are the main environmental concerns with respect to improper disposal of biomedical

waste management:

 Spread of infection and disease through vectors(fly, mosquito, insects etc.) which

affect the in -house as well as surrounding population.

 Spread of infection through contact/injury among medical/non-medical personnel

and sweepers/rag pickers, especially from the sharps (needles, blades etc.).

 Spread of infection through unauthorized recycling of disposable items such as

hypodermic needles, tubes, blades, bottles etc.

 Reaction due to use of discarded medicines.

 Toxic emissions from defective/inefficient incinerators.

 Indiscriminate disposal of incinerator ash / residues.

2.1.4.Biomedical waste management process:

Biomedical waste managementprocesses are as follows Waste Storage

Storage of waste is necessary at two points:

a. At the point of generation and

b. Common storage for the total waste inside a health care organization.

For smaller units, however, the common storage area may not be possible. Systematic

segregated storage is the most important step in the waste control program of the health care

establishment. For ease of identification and handling it is necessary to use color- coding, i.e.,

5 Recommended Labeling and Color Coding

A simple and clear notice, describing which waste should go to which container and how

frequently it has to be routinely removed and to where, is to be pasted on the wall or at a

conspicuous place nearest to the container. The notice should be in English, Hindi and

thepredominant local language. Preferably, it should have drawings correlating the container

in appropriate color with the kind of waste it should contain. Segregated Storage in Separate Containers (at the Point of Generation)

Each category of waste has to be kept segregated in a proper container or bag as

the case may be. Such container / bag should have the following property :

 It must be sturdy enough to contain the designed maximum volume and weight of the

waste without any damage.

 It should be without any puncture/leakage.

 The container should have a cover, preferably operated by foot. If plastic bags are to

be used, they have to be securely fitted within a container in such a manner that they

stay in place during opening and closing of the lid and can also be removed without

difficulty. Certification

When a bag or container is sealed, appropriate label (s) clearly indicatingthe following

information has to be attached. A water-proof marker pen should be used for writing. They

should be labeled with the ‘Biohazard’ or ‘cyto-toxic’ symbol as the case may be


 The containers should bear the name of the department/laboratory from where the

waste has been generated so that in case of a problem or accident, the nature of the

waste can be traced back quickly and correctly for proper remediation and if

necessary, the responsibility can be fixed.

 The containers should also be labeled with the date, name and signature ofthe person

responsible. This would generate greater accountability.

 The label should contain the name, address, phone/fax nos. of the sender as

well as the receiver.

 It should also contain name, address and phone/fax nos. of the person who

is to be contacted in case of an emergency.

Fig. 2.1: Biohazard symbol Common/Intermediate Storage Area

Collection room(s)/intermediate storage area where the waste packets/bags are collected

before they are finally taken/transported to the treatment/disposal site are necessary for large

hospitals having a number of departments, laboratories, OTs, wards etc. This is all the more

important when the waste is to be taken outside the premises. 7

. Parking Lot for Collection Vehicles

A shed with fencing should be provided for the carts, trolleys, covered vehicles etc. used for

collecting or moving the waste material. Care has to be taken to provide separate sheds for

the hazardous and non-hazardous waste so that there is no chance of cross contamination.

Both the sheds should have a wash area provided with adequate water jets, drains, raised

platform, protection walls to contain splash of water and proper drainage system.

2.1.5. Handling and Transportation of biomedical waste

This activity contains three components:

 Bags/containers used for collection of biomedical waste from waste storage.

 Inside the premises segregated waste transportation.

 Outsidewaste Transportation. Collection of waste inside the hospital/health care establishment

The collection containers for bio-medical waste have to be study, leak proof, of adequate size

and wheeled. Two wheeled bins of 120-330 liter capacity and four wheeled bins of 500-1000

liter capacity (IS 12402, Part I, 1988) may be used. The four wheeled containers have two fixed

wheels and two castors and they are fitted with wheel locking devices to prevent unwanted


8 Inside the Premises Segregated Waste Transportation

All attempts should be made to provide separate service corridors for taking waste matter

from the storage area to the collection room. Preferably these corridors should not cross the

paths used by patients and visitors. The waste has to be taken to the common storage area

first, from where it is to be taken to the treatment/disposal facility, either within or outside the

premises as the case maybe. Outside Waste Transportation

In case of off-site treatment, the waste has to be transported to the treatment/disposal facility

site in a safe manner. The vehicle, which may be a specially designed van, should have the

following specifications:

 It should be covered and secured against accidental opening of door, leakage/spillage


 The interior of the container should be lined with smooth finish of aluminium or

stainless steel, without sharp edges/corners or dead spaces, which can be

conveniently washed and disinfected.

 There should be adequate arrangement for drainage and collection of any run

off/leachate, which may accidentally come out of the waste bags/containers. The

floor should have suitable gradient, flow trap and collection container

 The size of the van would depend on the waste to be carried per trip.

 In case, the waste quantity per trip is small, covered container of 1-2 cu. m., mounted

on 3 wheeled chassis and fitted with a tipping arrangement can be used.

2.2Treatment process:

Some useful treatmentprocesses are as follows:

2.2.1 Autoclave Treatment

This is a process of steam sterilization under pressure. Steam is brought into direct contact

with the waste material for duration sufficient to disinfect the material in a low heat process.

These are also of three types: Gravity type, Pre-vacuum type and Retort type.


In the first type (Gravity type), air is evacuated with the help of gravity alone. The system

operates with temperature of 121 deg. C. and steam pressure of 15 psi. for60-90 minutes.

Vacuum pumps are used to evacuate air from the Prevacuum autoclave system so that the

time cycle is reduced to 30-60 minutes. It operates at about 132 deg. C. Retort type

autoclaves are designed to handle much larger volumes and operate at much higher steam

temperature and pressure.

2.2.2. Hydroclave Treatment

Hydroclave is ainnovative equipment for steam sterilization process (like autoclave). It is a

double walled container, in which the steam is injected into the outer jacket to heat the inner

chamber containing the waste. Moisture contained in the waste evaporates as steam and

builds up the requisite steam pressure (35-36 psi). Sturdy paddles slowly rotated by a strong

shaft inside the chamber tumble the waste continuously against the hot wall thus mixing as

well as fragmenting the same. In the absence of enough moisture, additional steam is


2.2.3 Microwave Treatment

This is a wet thermal disinfection technology although different from other thermal treatment

systems, which heat the waste on the exterior,microwave heats the targeted material from

inside out, providing a high level of disinfection.


Microwave technology has definite benefits, such as, absence of harmful air emissions (when

adequate provision of containment and filters is made), absence of liquid discharges, nonrequirement

of chemicals, reduced volume of waste (due to shredding and moisture loss) and

operator safety (due to automatic hoisting arrangement for the waste bins into the hopper so

that manual contact with the waste bags is not necessary). However, the investment cost is

high at present.

According to the rules, category no 3 (microbiology and biotechnology waste), 4 (waste

sharps), 6 (soiled waste) and 7 (solid waste) are permitted to be micro waved.

2.2.4 Chemical Disinfecting

This treatment is recommended for waste sharps, solid and liquid wastes aswell as chemical

wastes. Chemical treatment involves use of at least 1%hypochlorite solution with a minimum

contact period of 30 minutes or otherequivalent chemical reagents such as phenolic

compounds, iodine,hexachlorophene, iodine-alcohol or formaldehyde-alcohol combination

etc. Pre-shreddingof the waste is desirable for better contact with the waste material.In the

USA, chemical treatment facility is also available in mobile vans. Inone version, the waste is

shredded, passed through 10% hypochlorite solution(dixichlor) followed by a finer shredding

and drying. The treated material islandfilled.

2.2.5 Sanitary and Secured Land filling

Sanitary and secured land filling is necessary under the following circumstances:


 Deep burial of human anatomical waste when the facility of properincineration is not

available (for towns having less than 5 lakh populationand rural areas, according to

Schedule I of the MoEF rules – Securedlandfill).

 Animal waste (under similar conditions as mentioned above) – Securedlandfill.

 Disposal of autoclaved/hydroclaved/microwaved waste (unrecognizable) -Sanitary


 Disposal of incineration ash - Sanitary landfill.

 Disposal of bio-medical waste till such time when proper treatment anddisposal

facility is in place - Secured landfill.

 Disposal of sharps - Secured landfill. This can also be done within ahospital premises

as mentioned below.

In case disposal facility for sharps is not readily available in a town, healthcare

establishments, especially hospitals having suitable land, can construct aconcrete lined pit of

about 1m length, breadth and depth and cover the same with aheavy concrete slab having a 1

- 1.5 m high steel pipe of about 50 mm diameter.Disinfected sharps can be put through this

pipe. When the pit is full, the pipeshould be sawed off and the hole sealed with cement

concrete. This site should notbe water logged or near a bore well.

2.2.6 Incineration

This is a high temperature thermal process employing combustion of thewaste under

controlled condition for converting them into inert material and gases.Incinerators can be oil

fired or electrically powered or a combination thereof.Broadly, three types of incinerators are

used for hospital waste: multiple hearthtype, rotary kiln and controlled air types. All the types

can have primary andsecondary combustion chambers to ensure optimal combustion. These

arerefractory lined.In the multiple hearth incinerator, solid phase combustion takes place in

theprimary chamber whereas the secondary chamber is for gas phase combustion.

pyrolytic conditions with atemperature range of about 800 (+/-) 50 deg. C. The secondary

2.3 Toxicity of Biomedical Waste:

Biomedical waste is produced in all conventional medical units where treatment of (human or

animal) patients is provided, such as hospitals, clinics, dental offices, dialysis facilities, as

well asanalytical laboratories, blood banks, university laboratories.Health care waste refers to

all materials, biological or non-biological,that are discarded in any health care facility and

arenot intended for any other us. Within a health care facility or hospital, the main groups

submitted to risks are:

- Doctors, medical nurses, healthcare unit workers andmaintenance staff;

- Patients;

- Visitors;

- Workers in ancillary services: laundry, medical supplies store,those charged with collecting

and transporting waste;

- Service workers dealing with waste treatment and disposal ofhealth unit.

Regarding the health care workers, three infections are mostcommonly transmitted: hepatitis

B virus (HBV), hepatitis Cvirus (HCV), and human immunodeficiency (HIV) virus.

Among the 35 million health care workers worldwide, the estimations show [2,8] that each

year about 3 million receivehard exposures to bloodborne pathogens, 2 million of those

toHBV, 0.9 million to HCV, and 170,000 to HIV.Also, the workers involved in the collection

and treatment ofthe biomedical waste are exposed to a certain risk.

As a consequence, around the world there is seriously taken into consideration the

implementation of immunizationprograms, along with a proper biomedical waste

management.Risks generated by the chemical and pharmaceutical wasteare associated to the


potential traits of characteristics, such as:toxic, genotoxic, corrosive, flammable, explosive,


The sources of pharmaceutical waste are represented by:

- drugs administered intra venous;

- payment/ breakage of containers;

- partially used vials;

- unused or undated medications;

- expired medicines.


2.3.2 Heavy Metals

Incinerated ash contains heavy metals and salt content, which can pose potential toxicity

issues. Presence of salt content the leaching behavior of heavy metals can be changed, so

require proper management. Some heavy metals which occur in incinerated ash as Cd, Cu,

Ni, Pb, Hg, Zn, should create potential risk to the environment. Only Hg and Cd is soluble in

water other Ni, Pb, Cu, and Zn, all are solubilize in acidic condition so these are not leached

out in natural condition without acids or soluble salts. Cd and Cu mainly present in soluble

form, particularly in acid soluble form. So they are easy to be leached out in acidic condition.

2.4 Past Studies

Sufficient research work has not been done in literature concerning the utilization of

incinerated hospital waste(IHW). Most of the research works and publications are on the

utilization of incinerated municipal solid waste (IMSW) or fly ash produced by power plants.


As far as the utilization of IHW is concern this is a beginning era for its study and

applications. Municipal solid waste incineration ash is potentially useful material for

construction related work.



2.4 Solidification/Stabilization Process

Solidification/stabilization (S/S) techniques are analogous to locking the pollutant in the soil.

It is a process that physically encapsulates the contaminant. Thistechnique can be used alone

or combined with other treatment and dumping methods.


EPA has identified S/S treatment is a Best demonstrated Available Treatment Technology

(BDAT) for many Resource Conservation and Recovery Act (RCRA) hazardous wastes.

According to the EPA, solidification/stabilization (S/S) is often selected treatment technology

for controlling the sources of environmental contamination at Superfund program sites.

S/S is an effective treatment wide variety of organic and inorganic contaminants present in

contaminated soil, sludge and sediment. The ability to effectively treat a wide variety of

contaminants within the same media is a key reason why S/S is so frequently used in

remediation. Adding to the versatility of S/S treatment is the fact that contaminated material

can be treated in-situ (in place) or ex-situ as already segregated waste or excavated material.

S/S treatment involves mixing a binding reagent into the contaminated media or waste.

Although the terms solidification and stabilization sound similar, they describe different

effects that the binding reagents create to immobilize hazardous constituents. Solidification

refers to changes in the physical properties of a waste. The desired changes usually include an

increase of the compressive strength, a decrease of permeability, and encapsulation of

hazardous constituents. Stabilization refers to chemical changes of the hazardous constituents

in a waste


Solidification refers to a process in which waste materials are bound in a solid mass, often a

monolithic block. The waste may or may not react chemically with the agents used to create

the solid. Solidification is generally discussed in conjunction with stabilization as a means of

reducing the mobility of a pollutant. Actually, stabilization is a broad term which includes


solidification, as well as other chemical processes that result in the transformation of a toxic

substance to a less or non-toxic form.

2.4.1 Mechanisms of solidification/stabilization

Some successful solidification/stabilization mechanisms are as follows:-


2.4.2 Macroencapsulation

In this mechanism hazardous waste constituents are physically entrapped. When the

stabilized material degraded physically, the entrapped material free to migrate. Due to

environmental stresses the stabilized mass may break down above a time period. Therefore

contaminants stabilized by only macroencapsulation may find their way into the environment

if reliability of the mass is not maintained.

2.4.3 Microencapsulation

In micro encapsulation, hazardous waste constituents are entrapped with in the crystalline

structure of the solidified matrix at a microscopic level. The stabilized materials degrade into

relatively small particle sizes, most of the stabilized hazardous wastes remains entrapped.

2.4.4 Absorption

The process in which contaminants are taken into the sorbent in a large amount as sponge

takes on water. In absorption some solid material added as sorbent to take up or absorb the

free liquids in the wastes. This method is mainly employed to remove free liquid to improve

the waste- handling characteristics, that is, to solidify the waste.

Commonly used absorbents are as follows:

 Soil

 Fly ash

 Cement kiln dust

 Lime kiln dust

 Clay minerals including bentonite, kaolinite, vermiculture, and zeolite

 Sawdust

 Hay and straw

Some absorbents such as cement, kiln dust, have addition benefits due to their pozzolanic


2.4.4 Adsorption

By which contaminants are electrochemically bonded to stabilizing agents with in the matrix

thisphenomenon is known asAdsorption. These are normally surface phenomenon, and the

bonding may be through van der waal`s or hydrogen bonding. Contaminants that are

chemically adsorbed within the stabilized matrix are less likely to be released into the


environment than those that are not fixed. Adsorption is more permanent treatment for

solidification/stabilization in comparison of macroencapsulation or microencapsulation.

2.4.5 Precipitation

Precipitation is a stabilization processes will precipitate contaminants from the waste and

make more stable form of the constituents with in the waste. Precipitates such ascarbonates,

phosphates,silicates, sulfides, and hydroxides are then contained with in the stabilized mass

as part of the material structure.

2.4.6 Detoxification

Detoxification is a process in which a chemical constituent change into another constituent

that is either less toxic or nontoxic.

2.5Leaching Test methods

The first and foremost reason for selecting stabilization/solidification as a hazardous waste

management technique is a reduction in the rate at which contaminants can migrate into the

environment. After leaching the collected liquid is known as leachate.

Various leaching test methods are there:-

 Paint filter test

This test used to determine the absence or presence of free liquids in bulk and containerized

hazardous wastes. It is economical, rapid, easy to evaluate and easy to conduct. In a standard

paint filter wastes are placed and liquid is drained by gravity through the filter within 5

minutes, the hazardous waste is considered to contain free liquids and must be treated prior to

land filling. The stabilization/solidification process has been effective in eliminating free

liquids from the hazardous waste, this test may also used to determine the liquid after


 Liquid release test

After stabilization/solidification liquid release test is used to determine the liquid. In this test

a "consolidation" stress is applied to test how readily leachate can be squeezed from a

solidified mass.


 Extraction procedure toxicity test

This is an older regulatory test and used in the past to classify materials as

hazardous or non hazardous. Therefore it is considered a regulatory test not a design test, so

there is no realistic way to apply the results to any short of transport, fate or risk analysis.

Chapter 3

Experimental Programs


The main objectives of this research are:

1. To evaluate the engineering properties of incinerated hospital waste.

2. To study the leachate properties of incinerated hospital waste (IHW).

3. To carry out the solidification/stabilization of soil waste mixture using various

additives e.g. cement, rice husk ash and bentonite.

4. To evaluate the prospect of utilization of IHW in geotechnical engineering



3.2.1 Soil

Whitish color soil used in this study collected from a Village Dhuas of district Kushinagar of

Uttar Pradesh. The soil sample were collected from a depth of about 0.3 to 0.4 m below the

ground surface. The engineering properties and grain size distribution curve of the soil is

given in Table 3.1 and Fig 3.2 respectively.

Table 3.1: Engineering properties of soil

S. No Properties Typical value

1 I.S. Classification SM

2 Sand content, % 30.0%

3 Silt content, % 70.0%

4 Atterberg limits Non-plastic

5 pH value 5.8

6 MDD, g/cc 1.70

7 OMC, % 19.11

8 Permeability, k, cm/sec 1.8x 10-6

9 Specific gravity, G 2.92


Fig. 3.1: Soil used in stabilization/solidification

Fig. 3.2: Grain size distribution curve of soil


3.2.2 Incinerated Hospital Waste

The incinerated hospital waste was collected from Khalilabad. There is a incinerator plant of

SNG waste management having dual chamber direct combustion incinerator. On visual

inspection the IHW appeared dark grey colored and comes in powdered form. Sample were

directly collected from incinerator ash outlet in cement bags and brings to the soil mechanics

laboratory of M.M.M. engineering college, Gorakhpur. To evaluate the engineering

properties of IHW, it was passed through different sieves and filtered ash was used. The grain

size distribution was determined by mechanical sieve analysis (IS: 2720( Part 4) -1985) and

hydrometer (IS:2720 (Part 4)-1985 ) tests. A little amount about 4% of sodium metaphosphate

(NaPO3) was used as dispersing agent. The engineering properties and the grain

size distribution curve of IHW is given in Table 3.2 and Fig 3.4 respectively.

Table 3.2 Engineering properties of IHW

S. No. Properties Typical value

1 Maximum Dry Density g/cc 1.47

2 Free Swelling Index 0.7%

3 Optimum Moisture Content 18.11%

4 Specific Gravity 2.59

5 pH 8.0

6 Permeability, K 6.7x10-6

7 Atterberg limit Non- plastic

8 Sand content 50.0%

9 Silt content 50.0%

Fig. 3.3: Filtered IHW for Engineering properties Testing


Fig. 3.4: Grain size distribution curve of incinerated hospital waste (IHW)

3.3 Binders

For stabilization/solidification of soil-IHW samples, cement, rice husk ash, and bentonite

were used as binders.

There are a number of advantages of cement based stabilization. The technology of cement is

well known, including handling, mixing, setting and hardening. Cement is widely employed

in the construction field, and as a result, the material costs are relatively low and the

equipment and personnel readily available.

3.3.2 Rice husk ash

Rice husk is an agricultural waste obtained from milling of rice. About 10


tons of rice husk

is generated annually in the world. The ash has been categorized under pozzolana, with about

67-70% silica and about 4.9% and 0.95% aluminum and iron oxides, respectively. The silica

is substantially contained in amorphous form, which can react with the CaOH librated during

the hardening of cement to further form cementitious compounds. Chemical composition of

rice husk ash is SiO2, Al2O3, Fe2O3, CaO), and MgO as mentioned in various literatures and

the specific gravity of rice husk ash is 2.0. The chemical composition of rice husk ash (RHA)

is given in Table 3.3.

Table 3.3: Chemical composition of RHA (after Oyetola and Abdullahi 2006)

SiO2 86 %

Al2O3 2.6%,

Fe2O3 1.8%,

CaO 3.6%,

MgO 0.27%

3.3.3 Bentonite

Bentonite is a clay generated frequently from the alteration of volcanic ash, consisting

predominantly of smectite minerals, usually montmorillonite. Depending on the nature of

their genesis, bentonites contain a variety of accessory minerals in addition to

montmorillonite. These minerals may include quartz, feldspar, calcite and gypsum. The

presence of these minerals can impact the industrial value of a deposit, reducing or increasing

its value depending on the application. Bentonite presents strong colloidal properties and its

volume increases several times when coming into contact with water, creating a gelatinous

and viscous fluid. The special properties of bentonite (hydration, swelling, water absorption,

viscosity, thixotropy) make it a valuable material for a wide range of uses and applications.


3.4 Testing Procedure

Incinerated hospital waste ash and soil was mixed in various proportions and improvement in

the engineering properties was studied. Weight starting from a lower percentage was

considered in mixing till the stabilized soil continued to gain strength. The percentage of

additive (IHW) was increased at regular interval. The addition of percent ash discontinued

when the mix proportion resulted in decline in strength. Mixture of soil and incinerated

hospital waste sample were prepared by dry blending of soil and incinerated hospital waste in

different percentage by weight for conducting various tests and improvement in the

engineering properties has been studied.

In order to study the solidification/stabilization of optimum soil-IHW content, solidified

samples were prepared with various percentages of cement, rice husk and bentonite. An

increasing percentage of Cement, RHA and Bentonite was added till the sample continued to

gain the strength. When the mix proportion resulted in a decline in strength then investigation

was discontinued.

For studying of leaching properties, the mixture of soil + IHW as well as soil + IHW +

cement, Soil + IHW + RHA, Soil + IHW + bentonite are prepared on optimum moisture

content and maximum dry density. An experimental set up shown in Fig 3.5 and

recommended by show et al. (2003) was used, while standard guideliness for leaching tests

have not been established in India.

A 0.1 m thick sample was sandwiched between two layers of alluvial soil in a column of 0.15

m internal diameter and 0.5 m height. The alluvial layer was 0.1m thick above and 0.05 m

thick below the sample, which was compacted by hand in three layers. Distilled water was

added into the column to height of 20 cm of water above the top sand layer. Leachate

samples were collected at various intervals ranging from 1day to 30 days of testing. The


atomic absorption spectrophotometer is used for finding the concentration of heavy metals in


Fig. 3.5: Leaching Test setup after Shaw et al. (2003)


Chapter- 4

Result and Discussion

4.1. Soil Improvement Using Incinerated Hospital Waste (IHW)

Standard Proctor’s Compaction Test were conducted to determine the effect of various

percentages of incinerated hospital waste (IHW) on maximum dry density and optimum

moisture content and results of Soil-IHW mixture are plotted and appended as Fig. 4.1.

Fig. 4.1: Variation of moisture content and dry density with IHW (%) content

It is evident from Fig 4.1 that with addition of IHW, the optimum moisture content increases

as compared to the density of the virgin soil. This is due to consumption of water in hydration

of mixture during pozzolanic reaction with soil particle. It is also observed that with addition

of IHW, the maximum dry density increases upto the 9% IHW but it decreases with increase

in IHW beyond 9%. However the maximum dry density of virgin soil is more than the

density of soil+ IHW mix. This is due to fact that ash (IHW) is a lighter material as compared

to soil. So the density of soil+ IHW mix decreases. The increase in max dry density with

addition of IHW upto optimum percentage of IHW (i.e. 9%) is due to fact that addition of

IHW to soil results in improving the density by decreasing the void ratio( i.e. provide a

denser packing ). Beyond the optimum IHW content, the further addition of IHW will result

Variation of moisture content and dry density with % IHW







0 5 10 15 20 25

Moisture content %

Dry density (g/cc)

soil + 3% IHW

soil + 6% IHW

soil+9% IHW

soil +12% IHW



in excess of ash which remains un-used and prevents the soil particles from their point to

point contact with each other resulting to a decrease in density.

4.2 Leachate property of soil + IHW mix.

As incinerated hospital waste (IHW) contains some toxic metals, it is necessary to check the

migration of these toxic metals into soil due to leaching. Leaching test were conducted and

leachate samples were collected at various intervals ranging from 7 days to 28 days of curing.

The concentration of heavy metals present in leachate samples is given in table 4.1. The

permissible limits of effluents discharge on land.

Table 4.1: concentration of heavy metals present in the leachate of soil + IHW sample

S. No. Constituents


after 7



















Permissible limit

of effluent as per

Indian standards

(mg/l) refer to


1 Lead (Pb) 3.463 2.809 1.990 1.848 0.5

2 Copper (Cu) 2.040 0.382 0.279 0.102 3.0

3 Cadmium(Cd) 0.171 0.131 0.099 0.051 5.0

4 Chromium (Cr) 6.850 6.050 1.219 1.210 1.0

5 Nickel (Ni) 1.294 0.774 0.612 0.134 3.0

It is evident from Table 4.1 that the concentration of heavy metals such as lead (Pb) and

chromium (Cr) after 7 days curing of soil + IHW samples are around 3.463 mg/l and 6.850

mg/l which is about 592% and 585% more than permissible limit. These values may be

reduced to 417% and 368% after 28 days of curing. It is also found that conc. of Copper (Cu)

and Cadmium (Cd) are within the permissible limit. Thus it is clear that IHW cannot be

utilized in soil improvement unless the conc. of toxic metals gets reduced to the permissible

limit by solidification/stabilization.

4.3 Encapsulation/Solidification/Stabilization

Three different locally available additives were used in this study in order to encapsulate the

heavy metal present in soil + IHW mix.

4.3.1 Solidification/Encapsulation using Cement

Fig 4.2 presents the variation of moisture content and dry density with varying percentage of

cement mixed with soil + 9% IHW mixture.


Fig. 4.2: Variation of density and moisture content with % cement content

The optimum moisture content decreases as the percentage of additive (Cement) in soil + 9%

IHW increases. Upto 9% afterwards the optimum moisture content increases. After the

optimum percentage of cement is 9 % content, the dry density decreases. Thus 9% of the

cement is the optimum percentage for the solidification/encapsulation of soil + 9% IHW mix.

The observed behavior is having same explanation as explained in section 4.1.

4.3.2 Solidification/Encapsulation using Rice Husk Ash

It is evident from this figure 4.3 that there is an decrease in OMC and simultaneously there is

increase in MDD with the increase in RHA upto 6%. Rice husk ash contains silica and has a

good pozzolanic property. The RHA has good pozolanic characteristics which with hydrated

lime improves the strength of the mix. Having low air content and being a fine particle size,

high plastic in nature and due to its water retention property, lime forms an excellent bonding

with the RHA, IHW and soil which also improves its strength characteristics. This also

eliminates easy migration water to penetrate the mix. Further, addition of RHA causes

increase in unused RHA, content causing a decrease in MDD.







0 10 20 30

Dry density (g/cc)

Moisture content %

Variation of dry density and moisture content with %

cement content

soil + 9% ash + 6 %


soil + 9% ash + 9%


soil + 9% ash + 15%



Fig. 4.3: Variation of density and moisture content with % RHA content

4.3.3 Solidification using Bentonite

It is evident from this fig 4.4 that there is an increase in MDD and simultaneously there is

slight variation in OMC with the increase in % bentonite upto an optimum bentonite content

of 12% beyond which there is decrease in MDD. The maximum dry density increased with

the increase of bentonite content. Beyond 12%, the maximum dry density of bentonite-based

stabilized soil tends to decreases. This can be attributed to comparatively higher specific

gravity of bentonite.

Fig. 4.4: Variation of density and moisture content with % bentonite content

Variation of dry density and moisture content with %

RHA content








0 10 20 30

Moisture content %

Dry density

soil + 9% IHW + 3% RHA

soil+ 9%IHW + 6% RHA

soil+ 9%IHW + 9% RHA










0 10 20 30 40

Dry density (g/cc)

Moisture content %

Variation of dry density and moisture content with

%bentonite content

soil+9% IHW+6% bentonite



soil+9% IHW+15%bentonite


Fig. 4.5: comparison of MDD with various percentage of binders

In order to compare the effect of various binders/stabilizers on the maximum dry density, the

relationship between OMC and MDD is plotted and appended here with as Fig 4.5. It is

evident from this figure that mixing 12% of bentonite with soil + 9% IHW mix will give the

higher MDD whereas soil + 9% IHW + 6% RHA gave minimum MDD. However lichate

studies will be the best judgment.

4.4 Leachate properties of solidified/Encapsulate soil + IHW mix

The study of leachate is carried out with an aim to ascertain the effectiveness of

solidification/encapsulation of soil+IHW mix with cement, RHA, and bentonite. Leachate

contains a number of metals as lead(Pb), copper(Cu), cadmium(Cd), chromium(Cr) and

nickel(Ni). Leachate samples were collected at various intervals ranging from 7 day to 28

days of curing. We collect the leachate sample after seven days interval and found that the

concentration of metals is diluted regularly. The leachate test result are tabulated as Table

4.2, 4.3 and 4.4 for cement, bentonite and RHA.








0 5 10 15 20 25

MDD (g/cc)


Comperision of MDD with various percentage of binders






Table 4.2- concentration of heavy metals present in the leachate of soil + IHW+ Cement content

S. No. Constituents


after 7



















Permissible limit of

effluent as per Indian

standards (mg/l)

1 Lead (Pb) 2.50 1.08 0.76 0.51 0.5

2 Copper (Cu) 2.69 0.93 0.04 0.02 3.0

3 Cadmium


1.08 1.02 0.08 0.06 5.0

4 Chromium


2.64 1.43 0.04 0.02 1.0

5 Nickel (Ni) 1.54 0.97 0.06 0.04 3.0

Table 4.3- concentration of heavy metals present in the leachate of soil + IHW+ Bentonitesample

S. No. Constituents


after 7



















Permissible limit

of effluent as per

Indian standards


1 Lead (Pb) 2.09 1.68 1.24 0.94 0.5

2 Copper (Cu) 0.33 0.13 0.10 0.82 3.0

3 Cadmium(Cd) 0.32 0.10 0.87 0.62 5.0

4 Chromium (Cr) 4.25 1.10 0.70 0.40 1.0

5 Nickel (Ni) 0.94 0.41 0.38 0.19 3.0

Bentonite is quite active in encapsulation of heavy/toxic metals after 28 days of curing except

that it is not able to kept the lead (Pb) content within desired limit. Similar result are found in

case of using RHA as solidification/encapsulation agent. Soil + IHW mix solidified with

cement shows the encapsulation of all toxic metals after 28 days of curing. It is evident from

above mentioned tables that only cement is the most effective solidification/encapsulation

agent as compared to other solidification agents.


Table 4.4: concentration of heavy metals present in the leachate of soil + IHW+ RHA sample

S. No. Constituents


after 7




















limit of effluent

as per Indian



1 Lead (Pb) 3.643 3.096 2.589 1.60 0.5

2 Copper (Cu) 0335. 0.330 0.320 0.12 3.0

3 Cadmium (Cd) 0.385 0.143 0.139 0.98 5.0

4 Chromium (Cr) 6.850 5.311 4.685 3.64 1.0

5 Nickel (Ni) 2.340 1.497 1.371 1.12 3.0

4.5 Study of Scanning Electron Microscopy Imageries

SEM (Scanning Electron Microscope) imagery of soil, IHW, soil + 9% IHW + 9% cement

mix are given in Figure 4.6 to 4.9 respectively. It is clearly seen from above Figure that on

solidifying/encapsulating the soil = IHW with cement, the resultant structure is showing a

very dense packing of grains with very low void ratio. This leads to decrease in permeability

of mix as well as encapsulation of heavy metals present in soil + IHW.

Fig. 4.7: SEM Image of IHW at 1000X magnification


Fig. 4.6: SEM image of soil AT 1000X magnification

Fig. 4.8: SEM Image of soil + 9% IHW at 1000X magnification


Fig. 4.9: SEM Image of soil + 9% IHW + 9% cement mix at 1000X

4.2.5 Mixture of IHW, Soil and Rice Husk Ash (RHA)

Fig 4.10 shows the Scanning Electron Microscopic View at 1000X of mixture of IHW, Soil

and Rice Husk Ash (RHA)compacted on OMC which is 13.8 % .it is clearly seen from the

picture that there is also large number of voids and loose packing of soil grains which could

be the reason for its permeability and less strength in structure.

Fig. 4.1: SEM Image of soil + 9% IHW + 9% RHA mix at 1000X


Chapter 5


Based on the experimental study, it is found that incinerated hospital waste may be mixed

with soil for application in geotechnical engineering projects. It resolves the problem of

disposal of the IHW. Based on this study, the following Conclusions may be drawn:

1. The dry density of soil + IHW mix is less than that of virgin soil because IHW is

light weight material as compared with soil.

2. The optimum percentage of IHW to be mixed with soil is 9% as increase in IHW

content beyond 9% leads to decrease in MDD.

3. The soil stabilized/mixed with 9% of IHW shows a high conc. of heavy metal

such as Lead and Chromium. Migration of the same is expected and it may lead to

the contamination of water bodies.

4. It’s is found that cement is the best binder to be used for the

solidification/encapsulation of heavy metals in soil + IHW mix.

5. Leachate study confirms the encapsulation of heavy metals using cement after a

curing period of 28 days. It is found that 9% of cement is the optimum binder.

6. Concentrations of heavy toxic metals were found within permissible limits using

cement as solidifying/encapsulating agent.

7. SEM images showed the reduction in the porosity of soil + IHW mix when

solidified with cement.

8. Incinerated hospital waste (IHW) may be utilized in various geotechnical

Engineering Projects.