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Waste management is a common problem for most of the countries due to
excessive amounts of waste being generated, which includes both municipal as well
as industrial wastes. Disposal of waste has become increasingly expensive
and challenging. Land filling and incineration were the two options preferred
for waste disposal till the last decade. A majority of the waste generated (57%)
is disposed into the landfill, whereas some waste is incinerated (13-15%). With
land becoming scarce, fuel cost shooting up and rise in environmental concerns,
search for alternative waste treatment and disposal techniques is imperative
(Otoniel and Gerardo, 2003). Moreover, majority of the existing methods do not
satisfy the environmental regulations but plasma technology satisfies the
environmental regulations (Cherednichenko et
al., 2008). Incinerators are not preferred now
due to greenhouse gas emission as well as fly ash as residue, which requires
land filling. Plasma has been in use for various applications since long in space
programs, medical field, etc., but recently, it is applied to treat wastes. Plasma
technology and incineration are many times misunderstood as the same process. Table 1
shows the difference in both these process (Doug and David, 2000).
Plasma the fourth state of matter, is obtained by breaking down atoms
into ions and electrons by the process of ionization which creates extremely
high temperatures resulting in complete dissociation of
all components, organic as well as inorganic into their elemental compounds for recovery and recycling (Prasad,
2008). The organic component of wastes gets converted into synthesis gas which
mainly consists of hydrogen and carbon monoxide, whereas inorganic component of
wastes due to high temperature gets melted and are converted into inert and
non-leachable vitrified slag (Minutillo et
al., 2009). The distinct feature of plasma
gasification technology is its operation at very high temperature and an
oxygen-starved environment. The waste which is fed into the gasifier is subjected to
high temperature of 8,000 °C-10,000 °C in an oxygen starved environment.
Plasma gasification can be used for treating hazardous waste with an advantage of
useful by-products. |
