# Mycoremediation as a Potentially Promising Technology: Current Status and Prospects--A Review
## 3 Bioremediation (In Situ and Ex Situ)
### Merits and Demerits of Bioremediation
#### 3.3.2. Demerits of bioremediation  
Bioremediation has drawbacks and limitations, just like most treatment methods. Some chemicals, such as highly chlorinated compounds and heavy metals, are not readily susceptible to biological degradation and stabilization. Table 3 summarizes the classes of chemicals and their susceptibility to biodegradation. Additionally, microbial degradation of some chemicals may result in the production of substances that are more toxic or mobile than the parent compound(s). For instance, TCE undergoes a series of microbiologically mediated reactions in anaerobic environments, sequentially removing chlorine atoms from the molecule. This process is known as reductive dehalogenation. Vinyl chloride (VC), a known carcinogen, emerges as the final byproduct of this chain of reactions.  
In some cases, applying bioremediation without a thorough understanding of the microbial processes involved and the metabolic and chemical pathways could make the situation worse than it already is. Due to the complexity of the science of bioremediation, it must be tailored to a particular site's environmental and kinetic constraints to minimize their effects [126; 127]. Therefore, the initial costs for site assessment, characterization, and feasibility evaluation for bioremediation might be more expensive than those linked to more traditional technologies such as air stripping. To evaluate the efficiency of the bioremediation technique in its clean-up performance, extensive site monitoring is required during project implementation, just as with remediation technologies [128]. Monitoring requirements may include microbiological and chemical monitoring associated with chemical/physical remediation techniques. The implementation of bioremediation is also impacted by regulatory restrictions [129]. The advantages and disadvantages of bioremediation technologies are outlined in Table 4.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Factors** & **Merits** & **Demerits** \\ \hline \hline Natural Process & \
\begin{tabular}{c} Applies a biological strategy that uses \\ microorganisms to remediate polluted areas \\ \end{tabular} &
\begin{tabular}{c} The biological mechanism is very delicate and \\ necessitates the presence of microorganisms with \\ metabolic activity, favourable growth conditions, \\ and appropriate nutrients. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 4: Merits and demerits of bioremediation technologies.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Chemical Class** & **Examples** & **Biodegradability** \\ \hline Polyaromatic hydrocarbons & Benzo(a)pyrene, anthracene, creosote & Aerobic \\ Petroleum hydrocarbons & Fuel oil & Aerobic \\ Ketones and esters & MEK, Acetone & Anaerobic and aerobic \\ Aromatic hydrocarbons & Toluene, benzene & Anaerobic and aerobic \\ Asbestos & Not biodegradable \\ Corrosives & Caustics, inorganic acids & Not biodegradable \\ Radioactive materials & Cadmium, plutonium, uranium & Not biodegradable \\ Metals & Not degradable experimental biosorption \\ Organic cyanides & & Aerobic \\ PCBs & Arochlors & Some evidence; not readily degradable \\  & & Anaerobic (reductive dichloromethane), aerobic \\ Chlorinated solvents & & (methanotrophs) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Classification of chemicals and their bioremediation susceptibility.