Composition, impacts, and removal of liquid petroleum waste through bioremediation as an alternative clean-up technology: A review.

Exposure to hazardous wastes, especially petroleum wastes hydrocarbon (PWHCs), can damage human health and biological diversity. A huge amount of petroleum waste along with persistent organic pollutants is being generated during exploration and processing of crude oil. The dumping of petroleum waste hydrocarbons in an open pit contaminates the soil which can cause severe threats to human health and agro-geo-environmental ecosystem. The current study aimed to evaluate the mode of occurrence, composition, environmental, and health impacts of petroleum waste by using recent literature. The extracted results show that oil emulsion contains 48% oil, suspension 23%, settled emulsion 42%, and sludge emulsion 36%. The study discusses the possible biological techniques for rehabilitation of petroleum waste-contaminated areas. Several physical and chemical techniques are available for remediation of petroleum waste, but they are either costly or environmentally not feasible. Whereas, biological remediation namely, Bioremediation (Biostimulation and Bioaugmentation), Phytoremediation (Phytodegradation, Rhizoremediation, Phytovolatilization, and Rhizo-filtration) is a cheap and environmentally friendly way to remove petroleum waste hydrocarbons from contaminated soil and water. Some important enzymes (i.e., peroxidase, nitrilase, nitroreductase, phosphatase) and plant species i.e., Acacia and Chloris species are prominent methods to remediate the PWHCs. The knowledge assembled in this review is expected to create new doors for researchers to develop more efficient techniques to control the harmful impacts of PWHCs on the environment and health.

Geochemistry of subsurface water of Swabi district and associated health risk with heavy metal contamination.

Heavy metal (HM) contamination in the drinking water is a serious threat to the consumers and has drawn the global attention. In the current study, twenty six (26) groundwater samples including tube well and domestic bores were collected randomly from fourteen union councils (UCs) of tehsil Swabi. Depth of the tube wells ranged between 100 and 400 feet, while in domestic bore water, it ranged from 22 to 140 feet. Samples were analyzed for different parameters. Concentrations of the heavy metals (HMs) were found in the following increasing orders of Pb > Zn > Cr > Cu > Ni > Cd > Co in domestic well water while in tube well water, the increasing order was Cu > Ni > Co > Zn > Cr > Cd. In the domestic well samples, Cd, Cr, Ni, and Pb were found above the World health organization (WHO), permissible limits. Based on the Water Quality Index (WQI), samples collected from domestic wells were found of poor quality with WQI value of 208, while tube well waters were found of excellent quality, with WQI value of 40. This indicates that domestic well waters are more prone to HM contamination due to low depth. Health risk data showed significantly high risk (HQ > 1) for children upon domestic well water consumption, due to high concentrations of Cr and Pb. No significance relationship was observed between the various parameters which indicate the input of these contaminants from multiple sources.