Stabilization of Incinerated Hospital Waste Using Different Type of Binders: A Review

IJBSTR REVIEW PAPER VOL 1 [ISSUE 8] AUGUST 2013

ISSN 2320 – 6020

Stabilization of Incinerated Hospital Waste Using Different Type of Binders: A Review Arshi Hasan Khan and S. M. Ali Jawaid*

ABSTRACT- Disposal of solid and hazardous wastes has become a major issue in all industrialized countries.

Solidification/stabilization is accepted as a well-established disposal technique for hazardous waste. Solidification/stabilization (S/S) techniques are akin to locking the contaminants in the soil. It is a process that physically encapsulates the contaminant. This technique can be used alone or combined with other treatment and disposal methods. As a result many different types of hazardous wastes are treated with different binders .The stabilization/solidification of fly generated from incinerated hospital waste was studied with the objectives to reduce the leachability of the heavy metals present in the ash so as to permit their disposal in a sanitary landfill requiring only a lower degree of environmental protection. A treatability test can determine reagents required, percent bulking to be expected, and leachability of the mass after treatment. Reagents used include the following: Cement (OPC), RBI GRADE-81.

KEY WORDS: Unconfined Compressive Strength, California Bearing Ratio, RBI Grade 81, Ordinary Portland cement.

INTRODUCTION Hospital waste management by means of incineration processes one of the inconveniences method that generates solid residues, such as bottom and fly ash as well as off-gas cleaning residues with high levels of heavy metals, inorganic salts and other organic compounds (Anastasiadou et. al., 2012).According to bibliography, fly ash possesses a high content of heavy metals, dioxins and furans (Alba et al, 1997 For this reason it requires special management. Bottom ash was only recently included (2003) on the list of dangerous waste materials according to the Council of the European Union, while fly ash and solid waste coming from the fluglas control system have already found their place on the list of dangerous waste materials with codes 19.01.13 and 19.01.07, respectively (94/904/EC).

There is increasing concern about the disposal of hospital waste, the amounts of which have increased dramatically in recent years. The quantum of waste that is generated in India is estimated to be 1-2 kg per bed per day in a hospital and 600 gm per day per bed in a general practioner’s clinic e.g. a 100 bedded hospital will generate 100 – 200 kgs of hospital waste/day. It is estimated that only 5 – 10% of this comprises of hazardous/infectious waste (5 – 10kgs/day). The treatment and disposal of large volumes of these hazardous wastes, which have enormous potential to cause irreversible health damage, calls for an effective stabilization method. Medical waste incineration (MWI) produces large quantities of ash.

Author: Arshi Hasan Khanis currently pursuing master of technology program in environmental engineering in MMM. Engg.

College, Gorakhpur, India E-mail: arshihasankhn@gmail.com *Co-Author: S.M. Ali Jawaid is currently Associate Professor in MMM. Engg. College, Gorakhpur, India

The nature of the ash in terms of heavy metal content is complex, and has been the subject of many studies (Derie 1992; Forestier and Libourel 1998; Eighmy et al., 1998; Eudsen et al., 1999; Piantone et al., 2003). In response to a growing need for more stringent regulations regarding land filled hazardous waste, the Hazardous and Solid Waste Amendments of November 1984, required the U.S. EPA to promulgate regulations prohibiting the land disposal of untreated hazardous wastes. The U.S. EPA responded in November 1986, by proposing procedures for setting treatment standards, the toxicity characteristic leaching procedure (TCLP) as a test procedure to verify the acceptability of treated waste for land disposal and treatment standards based on the best available demonstrated technology (BDAT).

Solidification/stabilization (S/S) is a widely used treatment for the management/disposal of a broad range of contaminated media and wastes; particularly those contaminated with substances classified as hazardous. The treatment involves mixing a binding reagent into the contaminated media or waste. Solidification and stabilization refer to a group of cleanup methods that prevent or slow the release of harmful chemicals from wastes, such as contaminated soil, sediment, and sludge. These methods usually do not destroy the contaminants. Instead, they keep them from “leaching” above safe levels into the surrounding environment. Leaching occurs when water from rain or other sources dissolves contaminants and carries them downward into groundwater or over land into lakes and streams.

This review is a discussion of the published data relating to the ways in which the inclusion of hazardous wastes bearing heavy metals such as sludge, filter cakes, fly ash and slags affects the properties of cement and other binders.

E-mail: smaj@rediffmail.com

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IJBSTR REVIEW PAPER VOL 1 [ISSUE 8] AUGUST 2013

ISSN 2320 – 6020 Table 2: Chemical properties of ordinary Portland cement

Binders Ordinary Portland cement Ordinary Portland Cement (OPC) is the most widely used binder due to its cost effectiveness, availability and compatibility with a variety of wastes. (Spence et. al., 2004).

The stabilization of fly and bottom ash generated from incinerated hospital waste was studied. The objectives of the solidification/stabilization treatment were therefore to reduce the leachability of the heavy metals present in these materials so as to permit their disposal in a sanitary landfill requiring only a lower degree of environmental protection. In this case the bottom ash must be exanimate for its toxicity and all the necessary measures must be taken in order to minimize leaching of its hazardous components into the environment (Woolley et al, 2001). The degree of effectiveness of S/S product was established by strength and leaching tests. The experimental result shows the marked decrease in the toxicity with an increase in the strength of S/S product. In this review paper, the incinerated hospital wastes have achieved low compressive strength, in particular, wastes not containing lime, pozzolanic materials or high pollution level waste. In this study, in addition to S/S treatment, a compressive strength achievement for the final matrix was considered so that it could be used as a construction material. Then, for this purpose, solidification of the cement mortar is set as a constraint at the specimen preparation. Lombardi et al., (1998) has studied the mechanical properties of cement solidified, hospital solid waste incinerator fly ash. Fly ash and Portland cement mixtures in ratios varying between 0.25 and 1.5 were tested. The use of high volume fly ash in concrete has recently gained popularity as a resource-efficient, durable, costeffective, sustainable option for ordinary Portland cement (OPC) concrete applications (Crouch, E. K et.al.2007).

Shaswata Mukherjee et. al. (2012) showed the physical and chemical properties of ordinary Portland cement.

Comparing the present results with previous studies (Sukandar et al, 2006; Genazzini et al,2003; Aubert et al, 2006), regarding the content of fly ash produced the content of CaO is very high because of the pre-treatment with lime. Beside the CaO content, the results regarding the percentages of the other main oxides present in fly ash are in close agreement with the previous studies. The percentage of SiO2 and Al2O3 was substantially less.

Table 3: Chemical composition of fly and bottom ash and OPC

Table 1: Physical properties of ordinary Portland cement

Comparing the present results with previous studies, regarding the content of bottom ash produced at another HMWI in Greece (Gidarakos et al, 2009) and several other countries, such as Italy (Filipponi et al, 2003), Malaysia (Idris et al, 2002) and China (Zhao et al, 2003), a complete agreement was observed concerning the type of oxides that were present in the bottom ash of HMWI. Moreover, the results regarding the

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IJBSTR REVIEW PAPER VOL 1 [ISSUE 8] AUGUST 2013 percentages of various oxides present in bottom ash are in close agreement with the previous studies. The percentage of Na2O was higher in the bottom ash of this research, while the percentage of SiO2 and Al2O3 was again substantially less.

Compressive strength From previous studied cement-based solidification exhibited a compressive strength of 0-14.7 MPa (Figure 1). The strength decreased as the percentage of cement loading was reduced, the compressive strength being 0.22-9.96 MPa for 60%cement mixed with 40% bottom ash. The compressive strength reduced to 0-1.3 MPa when 30% cement was mixed with 70%bottom ash.

ISSN 2320 – 6020 environmental world, this has become an extremely important issues and the problem of how to prevent leaching of contaminated soil occupies the mind of many governments.

RBI GRADE 81 would be extremely effective in the binding of this contaminated soil, which can result in saving which cannot be estimated.

Solidification of soil using with RBI GRADE-1 Different percentage at which RHA was mixed with soil and 12% IHW and its OMC is given in table 4 and fig 2. From the table and graph it is clear that strength of the mixture is maximum when 12% IHW is added to the soil.

Table 4: Variation of OMC, MDD, CBR with 9% IHW.

Fig.1: Variation of density and moisture content with 12% IHW and 6%, 9%, 15%cement.

In Fig.1present the variation of moisture content and dry density with varying percentage of cement mixed with soil + 9% IHW mixture. The optimum moisture content decrease as the percentage of additive (cement) in soil + 9% IHW increase. Upto afterward the optimum moisture content was increased. After the optimum percentage of cement is 9% cement, the dry density decreases RBI Grade-81 RBI Grade-81 is a unique, cost-effective, environment friendly technological breakthrough in soil stabilization, waste binding and pavement layer design for the road and highway building world. RBI Grade-81 is a unique and highly effective natural inorganic soil stabilizer for infrastructure development and repair.

RBI Grade-81 was originally developed by RBI for South African Army Road Building International for the in the beginning of 1990's for pavement engineering applications RBI Grade-81 is a natural inorganic soil-stabilizer which reengineers & modifies the properties of soil to strengthen it for roads, paving and roads and pavement. Today growing

Fig.2: Variation of density and moisture content with 12% IHW and 4%, 8% RBI GRADE-1 The optimum moisture content decreases as the percentage of additive (RBI GRADE-81) in soil +12%IHW increase. Upto 12% afterward the optimum moisture content increases. After the optimum percentage of cement is 12% content, the dry density decrease.

Concluding Remark The comparison between two binders the optimum moisture content decreases as the percentage of additive (cement) in the

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IJBSTR REVIEW PAPER VOL 1 [ISSUE 8] AUGUST 2013 soil + 9% IHW increases. Up to 9% afterward the optimum moisture content increases. After the optimum percentage of cement is 9% content, the dry density decreases where RBI GRADE -81 is natural stabilizer the optimum moisture increases as the percentage of additive (RBI GRADE-81) in the soil +12% IHW.

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