Chapter 1
INTRODUCTION
Environmental awareness is increasing as India has embarked on a massive boost
to industrial and infrastructure development. The number of industries in India have
increased manifold in the last few decades changing the situation to an impressive
progressive prospect. Increased industrial production has resulted in the growth of this
country but concurrently it has also resulted in production of hazardous waste (HW).
Central Pollution Control Board (CPCB) has compiled state-wise inventory of hazardous
waste generating industries in a document “National Inventory of Hazardous Waste
Generating Industries and Hazardous Waste Management in India” in February 2009
based on the data received for the year 2007-08 from State Pollution Control Boards
(SPCB) and Pollution Control Committees (PCC) [CPCB, 2009]. As stated in the
document, there are 36,165 different HW generating industries generating 6.2 million
metric tons of HW every year in India. Of these, 2.7 million metric tons (43.78%) qualify
to be disposed off into a secured landfill while 0.4 million metric tons (6.67%) qualify for
incineration and remaining 3.1 million metric tons (49.55%) are categorized as
recyclable. The states of Gujarat, Maharashtra, and Andhra Pradesh are the top three
landfillable waste generating states [CPCB, 2010].
1.1. Indian regulatory framework
Hazardous waste generated by the industries can cause environmental pollution
and adverse health effects if not handled and managed properly. The Ministry of
Environment and Forests, Government of India, notified Hazardous Waste (Management
and Handling) Rules on July 28, 1989, under the provisions of the Environment
(Protection) Act of 1986 for effective management of HW, mainly solids, semi-solids and
other industrial wastes, which do not come under the purview of the Water (Prevention
and Control of Pollution) Act 1974 and the Air (Prevention and Control of Pollution) Act
1981.
These rules were further amended in the years 2000, 2003 and in September 2008
were repealed and the new rules entitled “Hazardous Waste (Management and Handling
and Trans boundary Movement) Rules 2008” (referred as HW (M, H & TM) Rules) were
notified. These rules were further amended in the year 2009. The rules define various
categories of hazardous waste based on the process listing (waste streams) and
concentration of hazard components. The Notification includes 26 rules, VII Schedules
and 15 forms [CPCB, 2010].
2
The objectives of these rules were to restore and maintain the chemical, physical
and biological integrity of the air, water and land environment for the nation. The rules
made it compulsory for industry to use specialized equipment and services for the storage,
handling, treatment, transportation and disposal of hazardous waste in an environmentally
sound manner. State Pollution Control Boards, pressure from non-governmental
organizations (NGOs) and environment activists are helping to bring about stringent
enforcement of pollution control rules.
HW has been defined as in rules 2009 as any waste which by reason of any of its
physical, chemical, reactive, toxic, flammable, explosive or corrosive characteristics
causes danger or is likely to cause danger to health or an environment, whether alone or
when in contact with other wastes or substances and shall include :
(i) Industrial process based hazardous wastes (Schedule 1): The industrial processes
based classification seeks to identify for various industries and processes from which
hazardous wastes are generated. This classification also identifies the wastes in a tabular
form making it easy for regulators to classify wastes into hazardous and non-hazardous
and includes wastes generated mainly from the 36 industrial processes (Annexure 1).
(ii) Concentration based standards for hazardous wastes (Schedule 2): In the
concentration based classification, the rules identify metals and organics whose presence
beyond a certain concentration renders it to be classified as hazardous. The wastes are
classified into five classes and their subsequent subclasses (Annexure 2).
(iii) General characteristics based hazardous wastes: This set of classification is based
on the general characteristics of the waste, called CRIT criteria as follows:
Corrosive (pH <2 or > 12.5): It corrodes metals or has a very high or low pH. This is
known as a "corrosive" waste. Examples are rust removers, acid or alkaline cleaning
fluids and battery acid.
Reactive (unstable, releases toxic fumes with water and other conditions): It is
unstable and explodes or produces toxic fumes, gases, and vapors when mixed with water
or under other conditions such as heat or pressure. This is known as a "reactive" waste.
Examples are certain cyanides or sulfide-bearing wastes.
Ignitable: (Flash Point < 60oC; oxidizers): It catches fire under certain conditions. This
is known as an "ignitable" waste. Examples are paints and certain degreasers and
solvents.
3
Toxic (classified on basis of Toxicity Characteristics Leachate Procedure, test
method as followed by USEPA, vide no: SW 846, till Indian standards are notified
by MoEF/CPCB): It is harmful or fatal when ingested or absorbed or it leaches toxic
chemicals into the soil or ground water when disposed of on land. This is known as a
"toxic" waste. Examples are wastes that contain high concentrations of heavy metals.
Refer table 1.1 for the contaminants concentration limits given in Management of
Hazardous Wastes, Guidelines for Proper Functioning and Upkeep of Disposal Sites,
HAZWAMS/32/2005-2006, and fig.1.1. for decision chart for waste categorization
[CPCB, 2006].
Table 1.1. TCLP test limits for heavy metals as per HAZWAMS/32/2005-2006
Sr. No.
Contaminant
TCLP Limit (mg/L)
1
Arsenic
5.0
2
Barium
100.0
3
Cadmium
1.0
4
Chromium
5.0
5
Lead
5.0
6
Mercury
0.2
7
Selenium
1.0
8
Silver
5.0
Organic contaminants from the standards are not mentioned
*Note:
1.
2.
3.
These limits shall be applicable till the notification of Leachate Standards (including Test Method)
under the E (P) Act, 1986
Best Demonstrated Available Technology (BDAT) standards shall be employed for parameters not
mentioned.
Leachate collected shall be treated and disposed as liquid effluent in compliance of the standards
notified under the E (P) Act, 1986.
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1.2. United States Environmental Protection Agency (USEPA) regulatory framework
In United States major regulatory considerations for clean up and disposal of
hazardous waste are primarily regulated by two federal laws and their amendments. First
is the Resource Conservation and Recovery Act (RCRA) of 1976 as amended by the
Hazardous and Solid Waste Amendments of 1984 (HSWA). These give USEPA,
authority to regulate disposal of hazardous waste and set standards for treatment. The
second major law regulating hazardous waste is the Comprehensive Environmental
Response Compensation and Liability Act (CERCLA) of 1980 as amended by the
Superfund Amendments and Reauthorization Act (SARA) of 1986. CERCLA regulates
the cleanup of spilled materials and abandoned hazardous waste sites [USEPA, 1993].
Toxic Substances Control Act (TSCA) regulates toxic chemicals and mixtures
that present an unreasonable risk of injury to human health or an environment. USEPA is
required to establish treatment standards for each type of RCRA hazardous waste. These
are established on the basis of the Best Demonstrated Available Technology (BDAT),
rather than on risk based or health based standards. “Best” is defined as the technology
5
that offers the greatest reduction of toxicity, mobility or volume of the waste. To be
“demonstrated” treatment technology must be demonstrated to work at a full scale level,
as opposed to bench scale or pilot scale. “Available” means that a technology is
commercially available [USEPA, 1993].
USEPA has listed specific hazardous wastes based on the criteria set forth in 40
CFR 261.11 under RCRA. If a waste meets the listing definition, it is presumed to be
hazardous, regardless of its concentration. The wastes are listed according to their
toxicity, reactivity, corrosivity and ignitability and includes a) nonspecific sources (F
codes), b) specific sources (K codes), c) commercial chemical products which are acutely
hazardous (P codes) and d) commercial chemical products which are non-acutely
hazardous ( U codes) [Wagner, 1991].
European Waste Catalogue has core list of 850 types of wastes, of these 420 are
classified as hazardous wastes and are divided into 19 main categories.
1.3. Treatment scenario
Waste minimization, reuse, recycle (reduce, reuse, recycle) at source, leads to
considerable onus upon the industries to develop methods, it is also important that safer
disposal methodologies should be developed at the end of the pipe line strategy. The HW
should be properly treated prior to its disposal. Treatment defined in HW (M, H & TM)
rules is a method, technique or process designed to change the physical, chemical or
biological characteristics or composition of any HW so as to render such wastes harmless
which essentially would mean to reduce the leachable properties apart from other criteria.
A few disposal methods (apart from reduce, reuse, recycle) are landfill and incineration.
Landfilling has been by far the most popular method employed in contaminated land
remediation due to its simplicity, reliability and relatively low cost [Harbottle et al.,
2007].
Inert wastes, which do not leach toxic metals or organics, can be landfilled at
Hazardous Waste Treatment, Storage and Disposal Facilities (TSDF) as per the
prescribed guidelines. Presently there are 26 common TSDFs in operation in 12 states,
across the country and 35 new sites notified are at different stages of development.
All the wastes, however, can not be put directly into the landfill. A landfill
operator comes across many metals bearing wastes which have leaching properties when
extracted with water or acid. These leached metals could impact the ground water or soil
in the immediate vicinity of a landfill. Even Government of India has formulated
6
guidelines for landfillable waste. One of the criteria which do not allow the wastes into
the landfill is based upon the concentration of pollutants in the leachate. CPCB has given
guidelines for proper functioning and upkeep of disposal sites and concentration limits for
acceptance of hazardous wastes for direct disposal to secured landfill under Hazardous
Waste Management Series, HAZWAMS/32/2005-2006 (table 1.2). These guidelines
mandate a few wastes to be treated in order to reduce the leachable properties of the
wastes to render them landfillable. There would be a need to stabilize (treat) these wastes
using a plethora of methods like solidification, alkali chlorination, neutralization,
hydrolysis, precipitation, encapsulation, etc. These treatment methods of wastes in
hazardous waste parlance are called stabilization methods, wherein wastes are subjected
to many processes and subsequently put into landfills. Stabilization process is effective in
treating a variety of difficult to manage wastes to render them suitable for landfilling or
for reuse or recycle.
Table 1.2. Concentration limits/criteria for acceptance of hazardous wastes for direct
disposal to secured landfill as per HAZWAMS/32/2005-2006
Leachate quality *
pH
Concentration
4-12
Total phenols
< 100 mg/L
Arsenic
< 1 mg/L
Lead
< 2 mg/L
Cadmium
< 0.2 mg/L
Chromium (VI)
< 0.5 mg/L
Copper
< 10 mg/L
Nickel
< 3 mg/L
Mercury
< 0.1 mg/L
Zinc
< 10 mg/L
Fluoride
< 50 mg/L
Ammonia
< 1000 mg/L
Cyanide
< 2 mg/L
Nitrate
< 30 mg/L
Calorific value
< 2500 Kcal/Kg
Strength
Unconfined Compression Test
> 50 KN/m2
*Leachate quality is based on water leach test.
7
1.4. Stabilization/solidification
As mentioned in subsection 1.3, solid waste management gives high priority to the
development of technologies addressed towards recycling and reuse. In the former case,
wastes are recycled to the same process from which they are generated, while in the latter
case, they are reused in a different process. High priority is also given to the recovery of
raw materials and energy from waste, however, these requirements can not always be
satisfied because a proper technology may be too expensive or may not be available. In
such circumstances, the priority is given to treatment processes which will reduce the
environmental impact of the wastes. Amongst these processes, stabilization/solidification
(S/S), are most suitable and are already widely used for the treatment of hazardous
industrial solid wastes. Cement based S/S often lead to formation of monolithic products
which may have potential to be used in the field of pre-formed building materials [Cioffi
et al., 2002].
The origin and development of S/S technology was first time described by Jesse
Conner, [1990]. S/S is a proven technology for the treatment of hazardous wastes. It
involves the addition of binders which can effectively achieve a) chemical treatment
(stabilization) of the hazardous wastes by converting the contaminants into less toxic,
mobile and insoluble and b) mechanical conversion (solidification) of the waste into a
durable, dense and monolithic entity with structural integrity that is more suitable for
storage, landfilling or reuse [Conner, 1990; Conner and Hoeffner, 1998; Marwa et al.,
2007].
S/S refers to the conversion of waste to a more chemically stable form. This
conversion may include solidification, but it often includes the use of physicochemical
reactions to transform the contaminants to less mobile or toxic forms [Means et al.,
1995]. It is an important tool in the treatment of sludge, soils and combustion residues
contaminated with hazardous materials. The process is increasingly being used in the
remediation of contaminated sites and has lot of advantages such as speed of
implementation, facilitation of rapid development of the site, reduction of offsite disposal,
reduced risk to site workers and use of well established techniques and equipment
[Harbottle et al., 2007].
The process
inhibits
leaching of hazardous
components
by reducing
waste/leachant contact and by forming a stable pH environment in which many heavy
metals of environmental concern remain insoluble [Fitch and Cheeseman, 2003]. It
involves mixing of hazardous wastes in the form of sludge or solid, into cementitious
8
binder system and is most suitable for treating predominantly inorganic wastes, especially
those wastes having heavy metals are considered to be more compatible with the types of
cementitious binders normally used [Roy et al., 1992a; Fatta et al., 2004].
Currently cementitious solidification/stabilization is recognized as the “BDAT” by
USEPA for the land disposal of most toxic elements (table 1.3) and for 57 RCRA listed
hazardous wastes. S/S technology was selected in 24% of all source control treatments at
Superfund remedial action sites in United States [USEPA, 2004]. Hence, they are most
widely used of all hazardous waste management alternatives [Kundu and Gupta, 2008].
The cementitious binder can be ordinary Portland cement (OPC) or admixtures of OPC
with fly ash. The technology aims to change the release process from a percolation
dominated mechanism to diffusion or surface–dissolution dominated regime. The wastes
are incorporated into the cement matrix and undergo physical and chemical change that
further reduces contaminant mobility. The mobility and possible release of metal
contaminants are decreased through their precipitation as hydroxides, adsorption or ion
substitution in cement hydration products and physical encapsulation in the solid matrix
[Islam et al., 2004]. Most hazardous wastes can be incorporated into a waste cement
system. The suspended pollutants would be incorporated into the final hardened concrete.
During this solidification process the concrete formation binds and strengthens the mass,
coats and incorporates some contaminants molecule in the siliceous solids and blocks
pathways between the pores. Thus this process is highly effective for waste components
with high levels of toxic metals. The alkaline matrices such as lime and cement are
commonly used in waste conditioning because they are inexpensive, readily incorporates
wet wastes and their alkalinity reduces the solubility of many inorganic toxic or
hazardous metals [Kundu and Gupta, 2008]. Typically hydroxides of metals are formed
which are less soluble as compared to other ionic species. Small amounts of fly ash or
bentonite can be added to alter porosity. It has been applied to the plating wastes
containing metals [USEPA, 1989a]. The technology appears both cost effective and safe
and its relative simplicity has made this an attractive pre-landfill waste treatment
technology that aims at making selected hazardous industrial wastes safe for disposal at
hazardous waste sites [ASTM 1989; USEPA, 1989a; Chang et al., 1999; Asavapisit et al.,
2003; Fitch and Cheeseman, 2003].
9
Table 1.3. BDAT for RCRA Wastes
Waste description
BDAT treatment
Barium
S/S (one alternative)
Cadmium
S/S ( one alternative)
Chromium
S/S (one alternative)
Lead
S/S
Mercury
S/S
Selenium
S/S
Silver
S/S
Wastewater treatment sludges
Alkaline chlorination + pptn + S/S
Spent CN plating bath solutions
Alkaline chlorination + pptn + S/S
Plating sludges from CN processes
Alkaline chlorination+pptn + S/S
Spent stripping and cleaning solutions
Alkaline chlorination + pptn + S/S
From CN processes
Spent CN solutions from salt bath cleaning Electrolytic oxidation +Alkaline
chlorination + pptn + S/S
BDAT: Best Demonstrated Available Technology
RCRA: Resource Conservation & Recovery Act
1.5. Literature review
Cement based S/S has been used extensively for treating inorganic solid wastes
containing heavy metals such as As, Cd, Cu, Ni, Pb and Zn [Bhatty et al., 1999]. Many
experimental and modelling studies are found in literature relating to the subject. S/S
processes are usually categorized based on the type of additives through which
solidification is achieved [Sharma and Lewis, 1994]. Each technique has certain
advantages and disadvantages. Cement and pozzolan based techniques are preferred
mainly due to low cost and good solidification characteristics [Parira and Yuet, 2006].
The formation of insoluble hydroxides is an important aspect of cement based S/S
technology. The solubility of Cd, Cr, Cu, Pb, Ni and Zn hydroxides decreases with
increasing pH upto pH 10 [Cullinane et al., 1986; Shi and Spence, 2004]. Above this pH,
the solubility increases with pH as the metal cations form soluble complex anions with
excess hydroxide ions. The variation of metal hydroxide solubility with pH is an
10
important factor for the S/S process because pore solution of hydrated cement paste is
highly alkaline [Mollah et al., 1995].
Arsenic containing waste can be solidified/stabilized with cement, fly ash and
Ca(OH)2. The formation of calcite seals the pores of the solidified sample and precipitate
formation of calcium arsenite whereas cement acts as a binder [Singh and Pant 2006;
Kundu and Gupta 2008].
The effects of Cr on different Portland cement phases and the solidification of Cr
in cementitious matrices have been studied by various researchers [Stephan et al., 1999;
Omotoso et al., 1996; Vallejo et al., 1999; Park, 2000; Trezza and Ferraiuelo, 2003; Fatta
et al., 2004; Halim et al., 2004; Polettini et al., 2004].
Copper can also be effectively immobilized using cement based and lime based
S/S treatment [Yukselen and Alpaslan, 2001; Fatta et al., 2004]. Zain et al. [2004] have
shown that the waste copper slag from blasting operation can be safely stabilized in
cement based system.
There are many studies on the S/S treatment of Ni with Portland cement [Roy et
al., 1992b, 1993, Fatta et al., 2004.] and cement fly ash [Roy et al., 1993]. Roy et al.
[1992b] observed that the hydration of Portland cement was retarded by Ni containing
sludge. They suggested that physical encapsulation of metal hydroxide by the cement is
principle mechanism of stabilization.
Lead concentration in leachate after S/S by Portland cement has been found to be
dependant on the leachate pH [Halim et al., 2003]. In a study using cement binders, Coz
et al. [2004] showed that the concentration of Zn in leachate under a wide range of pH
was very similar to that calculated based on the solubility of hydroxide ions.
Silveira et al. [2003] studied effectiveness of cement based systems for S/S of
spent potliner (SPL) inorganic fraction. They have concluded that cyanide and fluoride
mobilities were substantially reduced and S/S effectiveness for the leachable cyanides and
fluorides were 59.33 and 57.95% respectively. Sarla et al. [2004] have treated cyanide
successfully in aqueous solution with oxidation by chemical and photochemical process.
Malviya and Chaudhary [2006] reviewed factors affecting hazardous waste S/S.
The significant conclusions were design of S/S equipment and infrastructure depending
on the expected waste content or loading of the final waste form. Important parameters to
assess S/S are strength, setting time and extent of hydration. Metal bearing waste can
have either positive or negative effect on the strength development. Different waste
metals have different effects individually and in combination with binders in a S/S matrix.
11
Factors affecting strength development in order of importance are cement content, curing
time and water:solid ratio. Species like sulphate affect strength development. Sodium
sulphate affects S/S of a synthetic electroplating sludge in cementious binders with
microstructure and microchemistry study [Roy et al., 1992a]. Hydration can be retarded
depending upon the quantity and type of waste species. Setting time also changes with
waste addition. Carbonation affects waste by improving mechanical and chemical
properties. Gerven et al. [2007] have studied the effects of carbonation and leaching on
porosity in cement bound waste. The vulnerability of the stabilized waste to physical and
chemical attacks depends on factors such as permeability, chemical composition and
microstructure of the cement and incorporated waste aggregates [Klich et al., 1999].
Ageing and weathering affect chemical, physical and microstructure properties of waste
material. The effect of freezing and thawing and wetting and drying on solidified mercury
containing sludge was studied and degradation of solidified monoliths was observed
[Gordon, 1993]. Kearsley and Wainwright [2002] have established relationships between
porosity and strength. Despite interferences and some negative effects on cement
matrices, S/S waste with cement based techniques, clearly passes current quality
acceptance criteria for disposal in most cases.
Leaching models are important tools in evaluating the efficiency of
immobilization by S/S treatment technologies. The models can help to identify leaching
mechanisms and can provide methods for correlating leach data, estimate leaching of
contaminants over longer periods of time and may be helpful in developing improved
binder and additive formulations for S/S. SOLTEQ-B is a mathematical model developed
for predicting the behavior of S/S waste for risk assessment [Batchelor, 1998; Park and
Batchelor, 2002].
It was perceived from the literature review that there is scarce published research
work on the mixed waste with reactive and toxic contaminants. This was specially noticed
during data collection on treatments of Ba containing wastes. While there is some
accessible data on alkali chlorination of cyanide wastes, especially liquid wastes; very
less data is available on stabilization of solid wastes containing cyanide. Similarly, even
though available data on S/S of radioactive wastes containing barium exists; not much
information could be gathered on S/S of solid wastes containing Ba. There is a definite
need for investigating approaches for treatment of such wastes. The present work was,
therefore, undertaken with the specific objective of researching these wastes and
developing an effective technique for their remediation.
12
1.6. Waste material and contaminants
The machinery industry generate, cyanide from processes like plating, metal
finishing, heat treating and wet mining and pollute the environment. Metalworking and
finishing operations are large users of sodium, potassium, and calcium cyanides in heat
treating and nitriding operations. The quenching process in these operations produces
cyanide contaminated oils and wastes that need to be eventually disposed off. Quench
waters from hardening operations such as nitriding contains ferrocyanide as well as
cyanide [Conner, 1990]. The presence of untreated CN waste in landfill is potentially
hazardous because of the possibility of its impact on air, soil and groundwater. This
leaching shall have an adverse impact on human beings, if not handled appropriately.
Experimental studies of CN wastes (generated from heat treatment process) disposed in
landfills showed that between 72 and 82% of the CN was converted mostly to ammonium
and organic nitrogen compounds, whereas between 4 and 22% of the CN leached as free
or complex CN and up to 11% remained in landfill [Lagas et al., 1982]. Generally it is
present in waste streams as simple and complex cyanide, cyanates and nitriles. The
stability of cyanide complexes is pH dependent and hence their potential environmental
impacts can vary. Although, metal cyanide complexes by themselves are less toxic than
free cyanide, their dissociation releases free cyanide as well as the metal cation which can
also be toxic and may lead regulatory issues and environmental concerns [Sarla et al.,
2004; Dash et al., 2008].
The first category of RCRA listed hazardous wastes with F code includes
generally material specific wastes generated by a variety of processes. This category of
wastes includes solvent wastes, electroplating wastes, metal heat treating wastes and
dioxin coating wastes [Wagner, 1991]. The waste material considered for research studies
belonged to this category and the main contaminants were barium and cyanide.
All cyanide species are considered to be acute hazardous materials and have
therefore been designated as P-Class hazardous waste according to RCRA [Young and
Jordon, 1995]. Barium is one of the eight priority pollutants listed under RCRA metals as
toxicity characteristic metal for which USEPA has established required treatment level
using Toxicity Characteristic Leaching Procedure (TCLP) [Conner, 1997]. The other
metals listed are As, Cd, Cr, Pb, Hg, Se and Ag. Certain barium compounds such as
nitrate, chloride are relatively water soluble whereas the fluoride, carbonate, sulfate salts
have very low solubility. The water solubility of barium salts increases with decreasing
pH except for barium sulfate. There is no evidence that barium is carcinogenic however
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several cases of poisoning due to ingestion of barium compounds like chloride or
carbonate have been found to be toxic in adult humans [World Health Organization,
1990].
The metals in the waste can be treated by precipitation; but cyanide must be
removed prior to precipitation of metals since, it acts as a complexing agent which
inhibits precipitation [Chung, 1989]. It has been reported that, 59.33% effectiveness was
achieved in the cement based stabilization system for cyanide containing spent potliners
waste without any pretreatment for its removal [Silveira et al., 2003]. Cyanide is normally
destroyed by oxidation, specially, by alkali chlorination, which leads to its decomposition
to carbon dioxide and nitrogen [Clements and Griffins, 1985; Chung, 1989]. The fixation
or destruction of cyanide is of importance in stabilization/solidification. Barium can be
easily stabilized by precipitation, well below RCRA levels. Even with extremely high
barium wastes, sodium sulphate or gypsum can be added to any standard stabilization
formulation to precipitate barium as barium sulphate. Barium sulphate is not toxic due to
its low solubility 1.4 mg/L as barium in water [Conner, 1990, 1997].
1.7. Aims and objectives of this study
To devise a suitable treatment technique for the barium cyanide waste, generated by
engineering tools manufacturing industry, for its safe disposal into secured landfill at a
Common Hazardous Waste Treatment Storage Disposal Facility (CHWTSDF).
1.
Comprehensive characterization of the BaCN waste to establish its compliance
with regulatory norms.
2.
To identify and evaluate suitable additives, binders and waste:binder ratios during
the screening trials for final treatability experiments.
3.
To identify and evaluate suitable performance tests and techniques for efficacy of
stabilization.
4.
Optimization of stabilization process for final treatability experiments.
5.
Verification and in situ validation of the process.
6.
Cost evaluation.
Barium cyanide is one of the 57 listed RCRA wastes for which stabilization is
identified as one of the “BDAT” by EPA under code P013 (for commercial chemical
products) with Reference 55 FR 22561 [Means et al., 1995]. Hazardous waste can be
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stabilized in a variety of ways, but the main objective was to develop a recipe that
produces a stable and sustainable end product, which will pose minimal threat to the
environment [Sloot et al., 2007].
The stabilization trials on the said waste were undertaken initially in the
laboratory. The TSDF is provided with well equipped laboratory where laboratory as well
as onsite (in situ) trials were conveniently possible. The results obtained for S/S bench
scale experiments in laboratory were validated for safe disposal of waste in secured
landfill as per USEPA and CPCB guidelines. The research aspects of the study are
discussed in detail in subsequent chapters. The technology screening and materials and
methods used in the treatability experiments are discussed in next Chapter (2).
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