Environmental Conservation And Preservation

Published Date: 02 Nov 2017

A

Dissertation

on

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

in

Civil Engineering

With specialization in

Environmental Engineering

By

URMILA PAL

(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

Certificate

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

knowledge.

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

Supervisor

-------------------------------------------------------------------------------------------------------------

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

on………………..…

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

Madan Mohan Malaviya Engineering College,

Gorakhpur – 273 010 (Uttar Pradesh)

Acknowledgement

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

study.

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)

iii

Abstract

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-

ï‚· Lacking of natural resources such as rock, sand etc.

ï‚· 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.

iv

Contents

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

v

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

vi

LIST OF FIGURES

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

vii

LIST OF TABLES

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

viii

LIST OF ABBREVIATIONS

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

1

Chapter – 1

Introduction

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-

ï‚· Infectious waste- sharps, non-sharps, plastics disposables, liquid waste, etc.

ï‚· Non-infectious waste, radioactive waste, cytotoxic waste and discarded glass.

1.2 Classification of hospital waste

ï‚· 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.

ï‚· Pathological waste: Consists of tissue, organ, body part, human foetuses, blood and

body fluid. It is hazardous waste.

ï‚· 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

patients.

ï‚· 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.

ï‚· Pharmaceutical waste: This includes pharmaceutical products, drugs, and chemicals

that have been returned from wards, have been spilled, are outdated, or contaminated.

ï‚· Chemical waste: This comprises discarded solid, liquid and gaseous chemicals e.g.

cleaning, housekeeping, and disinfecting product.

ï‚· 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.

2

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.

Solidification/stabilization (S/S) could potentially play an important role in making wastes

acceptable for land disposal. S/S of IHW using by different types of binders as cement,

bentonite, and rice husk ash. One of the most important applications of S/S technology is to

treat hazardous wastes that contain toxic metals. S/S of hazardous waste containing mainly

inorganic chemicals and metals has been applied extensively (Al-Tabbaa and Prose, 1996).

The material used for solidification/stabilization (S/S) not only solidifies the hazardous waste

by chemical means but also insolublizes, immobilizes, encapsulates, destroys, sorbs, or

otherwise interacts with selected waste components. The results of these interactions are

solids that are non-hazardous or less hazardous than the original waste. S/S technologies

immobilize heavy metals by binding them and sulfates, cement-based S/S processes afford

physical entrap into a solid that is resistant to leaching using binders such as portland cement,

fly ash, and lime. (Parsa et. Al., 1996; Webster and Loehr; 1996). Besides chemical

immobilization, such as hydrogen ion concentration pH dependent precipitation involving

hydroxides, carbonates, and sulfates, cement-based S/S processes afford physical entrapment

potential for conditioning of toxic materials (Macias et. al., 1997). Physical entrapment is

accomplished through encapsulation of toxic materials or waste agglomerates with binders.

In present study, the relative effectiveness of these S/S products is defined basically by two

parameters strength and the leach resistance. MMD and OMC was evaluated by conducting a

series of Modified Proctor Test in laboratory. Maximum dry density (MDD) increases at a

point with increase in ash (IHW) percentage and then it decreases continuously. Different

types of binders used in solidification/stabilization (s/s) as cement, RHA, and bentonite. Also

it is observed that the concentration of heavy metals decreased in lechate sample in 28 day

leaching period in all type of S/S sample.

3

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

ï‚· 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.

ï‚· 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.

ï‚· 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

rabies.

ï‚· 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

hazard.

ï‚· Bio-Medical waste if not handled properly and within the stipulated time

-period could strike in the form of fatal infections.

ï‚· Lack of even basic awareness among hospital personnel regarding safe disposal of

Bio-Medical waste.

ï‚· Appropriate organization and management.

2.1.2. Current Issues in Management of Health Care Waste

There are two main issues at present:

ï‚· 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.

4

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

country. It would be necessary to implement proper bio-medical waste management system

for each and every hospital, nursing home, pathological laboratory etc. Comprehensive

management system for each and every health care establishment has to be planned for

optimal technoeconomic viability. At the same time, thefinal disposal for the whole town

must not be lost sight of. Since there are alarge number of small and medium health care

establishments, commontreatment and disposal facilities are essential.

2.1.3. Environmental Concern

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

waste management:

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

affect the in -house as well as surrounding population.

ï‚· Spread of infection through contact/injury among medical/non-medical personnel

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

ï‚· Spread of infection through unauthorized recycling of disposable items such as

hypodermic needles, tubes, blades, bottles etc.

ï‚· Reaction due to use of discarded medicines.

ï‚· Toxic emissions from defective/inefficient incinerators.

ï‚· Indiscriminate disposal of incinerator ash / residues.

2.1.4.Biomedical waste management process:

Biomedical waste managementprocesses are as follows

2.1.4.1. 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

use of specific colored container with liner / sealed container (for sharps) for particular

wastes. It must be remembered that according to the Rules, untreated waste should not be

storedbeyond a period of 48 hours.

2.1.4.2. 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.

2.1.4.3. 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 :

ï‚· It must be sturdy enough to contain the designed maximum volume and weight of the

waste without any damage.

ï‚· It should be without any puncture/leakage.

ï‚· 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.

ï‚· The sharps must be stored in puncture proof sharps containers. But before putting

them in the containers, they must be mutilated by a needle cutter, placed in the

department/ward itself. The bags/containers should not be filled more than 3/4th

capacity. Attempts should be made to designate fixed places for each container so that

it becomes a part of regular scenario and practice for the concerned medical as well as

non-medical staff. All bio-hazardous waste are required to be "red bagged" and

identified with symbol shown in fig 2.1.

2.1.4.4. 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

6

ï‚· 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.

ï‚· The containers should also be labeled with the date, name and signature ofthe person

responsible. This would generate greater accountability.

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

well as the receiver.

ï‚· 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

2.1.4.5. 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. Two rooms - one for the

7

general and the other for the hazardous waste are preferable. In case of shortage of the

general waste (non-hazardous) can be directly stored outside in dumper containers with lids

of suitable size. Arrangement for separate receptacles in the storage area with prominent

display of colour code on the wall nearest to the receptacles has to be made. When waste

carrying carts/containers arrive at this area, they have to be systematically put in the relevant

receptacle/designated area. rooms, the general waste (non-hazardous) can be directly stored

outside in dumper containers with lids of suitable size.

2.1.4.6. 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:

ï‚· Bags/containers used for collection of biomedical waste from waste storage.

ï‚· Inside the premises segregated waste transportation.

ï‚· Outsidewaste Transportation.

2.1.5.1. 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

rolling. There should be no sharp edges or corners, especially in metallic bins. Specifications of

bins are mentioned in chapter 4 of this manual. For convenience as well as for avoiding any

confusion, the color code applicable for the bags / containers should also be used for the bins.

Collection timings and duty chart should be put in a prominent place with copies given to the

concerned waste collectors and supervisors. For general waste from the office, kitchen,

garden etc., normal wheel-barrows may be used.

8

2.1.5.2. 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.

2.1.5.3. 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:

ï‚· It should be covered and secured against accidental opening of door, leakage/spillage

etc.

ï‚· 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.

ï‚· 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

ï‚· The size of the van would depend on the waste to be carried per trip.

ï‚· 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.

9

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. Autoclave treatment has been recommended for microbiology and

biotechnology waste, waste sharps, soiled and solid wastes. This technology renders certain

categories (mentioned in the rules) of bio-medical waste innocuous and unrecognizable so

that the treated residue can be landfilled. SanjayGandhiMemorialHospital in Delhi has

installed a Prevacuum Autoclave.

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

injected. The system operates at 132deg.C. and36 psi steam pressure for sterilization time of

20 minutes. The total time for a cycle is about 50 minutes, which includes start-up, heat-up,

sterilization, venting and depressurization and dehydration. The treated material can further

be shredded before disposal. The expected volume and weight reductions are up to 85% and

70% respectively. The hydroclave can treat the same waste as the autoclave plus the waste

sharps. The sharps are also fragmented. This technology has certain benefits, such as, absence

of harmful air emissions, absence of liquid discharges, nonrequirement of chemicals, reduced

volume and weight of waste etc. TataMemorialHospital in Mumbai has installed the first

hydroclave.TataMemorialHospital in Mumbai has installed the first hydroclave inIndia in

September 1999.

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.

10

The input material is first put throughout a shredder. The shredded materials are pushed to a

treatment chamber wherever it is moistened with high temperature steam.

The materials are then carried by a screw conveyor beneath a series (normally 4-6nos.) of

conventional microwave generators, which heat the material to 95-100deg. C. and uniformly

disinfect the material during a minimum residence time of 30 minutes and total cycle is of 50

minutes. A second shredder fragments the material further into unrecognizable particles

before it is automatically discharged into a conventional / general waste container. This

treated material can be landfilled provided adequate care is taken to complete the microwave

treatment. In the modern versions, the process control is computerized for smooth and

effective control.

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:

11

ï‚· 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.

ï‚· Disposal of autoclaved/hydroclaved/microwaved waste (unrecognizable) -Sanitary

landfill.

ï‚· Disposal of incineration ash - Sanitary landfill.

ï‚· Disposal of bio-medical waste till such time when proper treatment anddisposal

facility is in place - Secured landfill.

ï‚· 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.

These are referred to as excess air incinerators because excess air is present in boththe

chambers. The rotary kiln is a cylindrical refractory lined shell that is mountedat a slight tilt

to facilitate mixing and movement of the waste inside. It hasprovision of air circulation. The

kiln acts as the primary solid phase chamber,which is followed by the secondary chamber for

the gaseous combustion. In thethird type, the first chamber is- operated at low air levels

followed by an excess airchamber. Due to low oxygen levels in the primary chamber, there is

better controlof particulate matter in the flue gas.In a nut- shell, the primary chamber has

12

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

chamber operatesunder excess air conditions at about 1050 (+/-) 50 deg. C (Schedule V of the

Rules). The volatiles are liberated in the first chamber whereas they are destroyedin the

second one. Some models are fitted with Educators mechanism, whichmaintains the system

under negative pressure and helps control the flue gasesmore effectively. The chimney height

should be minimum 30 meters above groundlevel. Installation of incinerators in congested

area is not desirable.In the Bio-medical Waste (Management and Handling) Rules,

Incinerationhas been recommended for human anatomical waste, animal waste, cyto-toxic

drugs, discarded medicines and soiled waste.

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

13

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

teratogenic,mutagenic.

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.

Larger amounts of such biomedical waste occur whenunwanted or expired chemical and

pharmaceutical products areremoved. These can cause poisoning by absorption through the

skin or mucous membranes, by inhalation or by ingestion. Chemicals and pharmaceuticals

may also determine lesions ofskin, eye, and respiratory mucosa. The most common injuries

are the burns. Chemical waste removed by drainage system mayhave toxic effects on

ecosystems and water where aredischarged. Similar effects may have the pharmaceuticals

whichcontain antibiotics or other drugs, heavy metals, disinfectantsand antiseptics.Risks

associated to final elimination of biomedical wasteshould be also considered within a health

care andenvironmental protection program. Incineration of medicalwaste containing plastic

Dioxin is a known carcinogen.

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.

14

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.

Sagambati, S. A. (1985) A wide range of soils can be stabilized using fly ash. They

demonstrated the use of fly ash as foundation medium reinforced with jute geotextile.

Akthar et al. (1990) studies the performance of various combination of cement (OPC), flyash,

blast furnace slag, lime and silica fume to treat the heavy metal contaminated soil. He

also quoted that OPC is very versatile and dependable reagent compared to other agents.

Abdul –Rashid and Frantz (1992) works on the physical properties of incineration fly ash, are

quite similar to coal fly ash evaluate engineering properties for geotechnical applications

(Parker et. al, 1977; Edil et. al, 1987). With the large quantities of incineration fly –ash, there

is an immediate need for acceptable disposal method other than land-filling, which has

become undesirable (Poran et al., 1989). several study were carried out over the last few

decade established that both coal fly ash and solid waste incinerated fly-ash have favorable

engineering characteristics for geotechnical application (Sherwood and Ryley1986; Show et

al.2003).

Rachna and choudhary (2006) reviewed the various factors affecting hazardous waste

solidification/stabilization. They found that the performance of solidified/stabilized product

can be improved by additives like silica fumes, sulphur polymers, CaCl2, Ca(OH)2, Na2So4

and K2So4.

Zhang et al (2009) develops a methodology for analysis of physicochemical characteristics of

municipal solid waste incineration (MSWI) fly ash. In this work, microstructure, particulate

size distribution and components of fly ash were investigated using SEM, laser particulate

description analyzer, ICP, XRF, IR and XRD. He found that content of chemical components

follows sequence of CaO> Al2O3 > Fe2O3>MgO> K2O > Na2O, and fly ash register a SiO2-

Al2O3- metal oxides system as total content of these oxides exceeds 80%. Major

mineralogical compononts of fly ash involve SiO2, CaCl2, Ca3Si2O7, Ca2SiO4.35H2O,

Ca9Si6O21.H2O, K2Al2Si2O8.8H2O and AlCl3.4Al(OH)3.4H2O.

15

Based on experimental observations Jawaid And Kaushik (2011) established thatHospital

Solid IncineratedAsh (HSWIA) is suitable as an admixture for soil stabilization. It help to

resolve the problem of disposal and also to improve the soil properties. The result shows that

soil HSWI mix has certain cementitious property. The presence of high percentage of heavy

metals such as lead (Pb), nickel (Ni), chromium (Cr) and cadmium (Cd) may lead to the

contamination to water bodies. They reported that S/S of HSWIA is need of time.

LIU Han qio et al. (2009) used MSWI fly ash for sediment solidification instead of cement

for studying its feasibility. It showed MSWI fly ash can solidified body having a suitable

amount of water with appropriate incorporation, thus improving its compression

performance. The compressive strength of solidified body can reach 0.24 MPa at 7day which

is conflicted by 20% MSWI fly ash instead of 10% cement in solidifying agent. Its leaching

concentration of heavy metal is far lower than the toxicity standard of landfills.

Soils can be stabilizedby mixing the correct proportion of sandy and clay soil or

bymechanical compaction of natural soil that increases the strengthand cohesion(Ghavami et

al. 1999; Bouhichaet al.2005). Use of stabilizers is not new—natural oils, plantjuices, animal

dung, and crushed anthills have been used for many centuries. (Bahar et al. 2004; Al-Rawas

et al. 2005, Hossain and Lachemi 2005; Chen and Lin2009; Al-Amoudi et al. 2010).Scientific

techniques of soil stabilization have been introducedin recent years and the use of

cementitious material like Portlandcement, hydraulic lime, bitumen, asphalt, and certain

resins asstabilizers is quite common.

Pozzolanic stabilizers can bind soilparticles together and reduce water absorption by clay

particles.The potential for using industrial by-products such as blast furnaceslag, fly ash, rich

husk ash, foundry sand, foundry slag, bottom ash,and cement kiln dust for stabilization of

clayey soils is promisingand has been investigated.(Rahman 1986; Ferguson 1993; Chu and

Kao 1993; Dawson et al. 1995; Kaniraj and Havanagi 1999; Millerand Azad 2000; Sezer et

al. 2006; Moon et al. 2009)

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.

16

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. The desired changes include converting the constituents into a less soluble,

mobile, or toxic form. S/S treatment involves mixing a binding reagent into the contaminated

media or waste. Binding reagents commonly used include portland cement, cement kiln dust

(CKD), lime, lime kiln dust (LKD), limestone, fly ash, slag, gypsum and phosphate mixtures,

and a number of proprietary reagents. Due to the great variation of waste constituents and

media, a mix design should be conducted on each subject waste. Most mix designs are a

blend of the inorganic binding reagents listed above. Binding reagents that are organic have

also been tried. These include asphalt, thermoplastic, and urea-formaldehyde. Organic

binding reagents are rarely used in commercial scale due to their high cost compared to

inorganic binders.

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

17

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

substance to a less or non-toxic form.

Experts often speak of the technologies collectively as solidification and stabilization (S/S)

methods. Chemical fixation, where chemical bonding transforms the toxicant to non-toxic

form, and encapsulation, in which toxic materials are coated with an additive are processes

referred to in discussions of S/S methods. There are currently about 40 different vendors of

S/S services in the United States, and though the details of some processes are privileged,

many fundamental aspects are widely known and practiced by the companies.

S/S technologies try to decrease the solubility, the exposed surface area, and/or the toxicity of

a hazardous material. While the methods also make wastes easier to handle, there are some

disadvantages. Certain wastes are not good candidates for S/S. For example, a number of

inorganic and organic substances interfere with the way that S/S additives will perform,

resulting in weaker, less durable, more permeable solids or blocks. Another disadvantage is

that S/S often double the volume and weight of a waste material, which may greatly affect

transportation and final disposal costs (not considering potential costs associated with

untreated materials contaminating the environment). S/S additives, such as encapsulators, are

available that will not increase the weight and volume of the wastes so dramatically, but these

additives tend to be more expensive and difficult to use.

Methods for S/S are characterized by binders, reaction types, and processing schemes.

Binders may be inorganic or organic substances. Examples of inorganic binders which are

often used in various combinations include cements, lime, pozzolans, which react with lime

and moisture to form a cement such as fly ash, and silicates. Among the organic types

generally used are epoxies, polyesters, asphalt, and polyolefins (e.g. polyethylene). Organic

binders have also been mixed with inorganic types, e.g., polyurethane and cement. The

performance of a binder system for a given waste is evaluated on a case-by-case basis;

however, much has been learned in recent years about the compatibility and performance of

binders with certain wastes, which allows for some intelligent initial decisions related to

binder selection and processing requirement.

2.4.1 Mechanisms of solidification/stabilization

Some successful solidification/stabilization mechanisms are as follows:-

18

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:

ï‚· Soil

ï‚· Fly ash

ï‚· Cement kiln dust

ï‚· Lime kiln dust

ï‚· Clay minerals including bentonite, kaolinite, vermiculture, and zeolite

ï‚· Sawdust

ï‚· Hay and straw

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

characteristics.

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

19

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:-

ï‚· 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

stabilization.

ï‚· 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.

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ï‚· 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.

ï‚· Toxicity characteristic leaching procedure (TCLP)

The U.S. EPAunder the hazardous and solid waste amendments of 1984 was adopted the

toxicity characteristic leaching procedure on November 7, 1986. This is a regulatory test. The

effectiveness of stabilization is evaluated by TCLP. The TCLP is subject to disapproval with

respect to its use for the evaluation of stabilization effectiveness for several reasons. It reduce

the beneficial effects of macro encapsulation and microencapsulation because a solidified

monolithic mass is broken down to pass the 9.5 mm sieve. The low pH environment during

extraction may be representative in a landfill containing domestic garbage, although it may

not be representative of the real world field conditions. Though, having a high

alkalinitystabilized material like cement based stabilization, may quickly increase the pH of

the leachant and in the result in leaching under basic rather than acidic condition. even with

these criticism, the TCLP is used to determine the effectiveness comparison of one treatment

technology with another or one stabilization mix or process with another. The TCLP test may

yield concentration can be compared to standards or leachate concentration obtained using

alternative stabilizing technique and mixes. 21

Chapter 3

Experimental Programs

3.1 OBJECTIVES

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

applications.

3.2 MATERIALS USED

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

22

Fig. 3.1: Soil used in stabilization/solidification

Fig. 3.2: Grain size distribution curve of soil

23

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

24

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.

3.3.1 Cement

Cement is a principal reagent which frequently used for the stabilization of hazardous waste.

For cement based stabilization, waste materials are mixed with cement followed by the

addition of water for hydration, because the waste does not have enough water. Cement based

stabilization is best suited for inorganic wastes, especially those containing heavy metals. As

a result of the high pH of the cement, the metals are retained in the form of insoluble

hydroxide or carbonate salts within the hardened structure. Stabilization with cement has

been used for the fixation of inorganic wastes such as metal hydroxide sludges and metal

contaminated soils. The wide use of stabilization of inorganics derives from

25

ï‚· The lack of better alternatives (for example, metals do not biodegrade and do not

change in atomic structure when incinerated )

ï‚· Available and understood physiochemical mechanisms such as precipitation and

adsorption.

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

8

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.

26

Bentonite's adsorption/absorption properties are very useful for wastewater purification.

Common environmental directives recommend low permeability soils, which naturally

should contain bentonite, as a sealing material in the construction and rehabilitation of

landfills to ensure the protection of groundwater from the pollutants. Bentonite is the active

protective layer of geosynthetic clay liners.

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