One of the foremost solid wastes produced by petrochemical industries is oily sludge. Oily sludge being a mixture of various kinds of hydrocarbons has been characterised as a hazardous waste by Environment Protection Act and Hazardous Wastes Handling Rules which contributes a lot in environmental pollution. Polycyclic aromatic hydrocarbons (PAHs), which are components of crude oily sludge, represent serious environmental concerns, as most of them are mutagenic, cytotoxic and carcinogenic. Several methods for degradation of oily sludge and other petroleum related contaminants have been discussed in literature. This review paper presents the most efficient process of remediating these contaminants from environment, i.e., biodegradation by microorganisms. It is attaining significance as an increasingly efficient and potentially inexpensive cleanup strategy. Its potential contribution as a countermeasure biotechnology for decontamination of oil polluted systems could be vast, as it also leads towards mineralisation of complex organic compounds to simple compounds enhancing soil organic contents. So it can be concluded that biodegradation strategy of petroleum oily sludge, even with some limitations, have proved to be one of the most cost effective and promising technology with potential application in land farming.
Persistent Organic Pollutants (POPs) include a wide range of compounds including dichlorodiphenyltrichloroethanes’ (DDTs), hexachlorocyclohexanes (HCHs), polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). These pollutants are present everywhere on earth i.e. soil, water and air. Their excessive use has adversely affected all ecosystems and their components including marine and freshwater, wildlife and human health. Although the use of POPs has been banned in many countries but they are still in use in many developing countries. This paper presents the sources and distribution of different POPs with special reference to their adverse effects and possible routes of contamination. Moreover, accumulation of these persistent pollutants in different body parts of fishes from major locations in Pakistan and its neighbouring countries (India, China and Iran) has been presented which exhibits their risk assessment for these important bioindicators of aquatic environments.
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