The current study was carried out in Gadoon Amazai industrial estate and surrounding areas in order to investigate environmental pollution resulted from various industries. The industries flush their effluents in the surrounding areas without treatment, which can contribute toxic elements and compounds to the soil and also to groundwater of nearby areas. The toxic metals have high potential ecological risk to surrounding environment. A continuous field survey was conducted to find out flow of industrial effluent in surrounding area. For determining major and toxic metals in soil, a random sampling technique was followed to collect representative samples. A total of 45 samples were collected with 25 soil samples from target areas and 20 samples from the reference areas. For the toxic and heavy metals, 1 g powder soils (−200 mesh size) was treated with hydrofluoric acid (10 ml), aqua regia (20 ml), and HCl (20 ml). For the major elements, 0.5 g samples was treated with hydrofluoric acid (10 ml) and perchloric acid (4 and 2 ml with 2-h interval). All these soil samples were analyzed for 13 major and toxic metals using Perkin Elmer atomic absorption spectrophotometer (AAS-700) equipped with graphite furnace (GF). The results showed that the mean concentrations (mg/kg) of toxic, heavy, and major elements in target area are 301.6, 8.8, 152.3, 58.8, 144.7, 359.4, 32.5, 1097, 2508, 786.5, 2572, 4088, and 689.8 for Cr, Cd, Pb, Ni, Cu, Zn, Co, Fe, Mn, Mg, Na, Ca, and K, respectively. The mean concentration (mg/kg) for toxic and major elements in the reference area are 93.6, 6.1, 35.5, 55.9, 59.1, 116.4, 24.1, 644.3, 1112, 549.0, 1275, 2364, and 995.2 for Cr, Cd, Pb, Ni, Cu, Zn, Co, Fe, Mn, Mg, Na, Ca, and K, respectively. Several approaches such as pollution load index, ecological risk index, geo-accumulation index, enrichment factor, etc. were applied in order to infer anthropogenic contributions. This study indicated that majority of the toxic and major elements contribute to soil pollution, but the toxic metals have high influence on the environment as compared to major elements. Therefore, industrial and commercial activities in the area are the main cause of higher potential ecological risk, as compared to the reference areas. There is strong need for remediation and mitigation measures in the study area, which could help to minimize the environmental pollution produced by the industrial estate.

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.

Nano-bioremediation application is an ecologically and environmentally friendly technique to overcome the catastrophic situation in soil because of petroleum waste contamination. We evaluated the efficiency of oil-degrading bacterial consortium and silver nanoparticles (AgNPs) with or without fertilizer to remediate soils collected from petroleum waste contaminated oil fields. Physicochemical characteristics of control soil and petroleum contaminated soils were assessed. Four oil-degrading strains, namely Bacillus pumilus (KY010576), Exiguobacteriaum aurantiacum (KY010578), Lysinibacillus fusiformis (KY010586), and Pseudomonas putida (KX580766), were selected based on their in vitrohydrocarbon-degrading efficiency. In a lab experiment, contaminated soils were treated alone and with combined amendments of the bacterial consortium, AgNPs, and fertilizers (ammonium nitrate and diammonium phosphate). We detected the degradation rate of total petroleum hydrocarbons (TPHs) of the soil samples with GC-FID at different intervals of the incubation period (0, 5, 20, 60, 240 days). The bacterial population (CFU/g) was also monitored during the entire period of incubation. The results showed that 70% more TPH was degraded with a consortium with their sole application in 20 days of incubation. There was a positive correlation between TPH degradation and the 100-fold increase in bacterial population in contaminated soils. This study revealed that bacterial consortiums alone showed the maximum increase in the degradation of TPHs at 20 days. The application of nanoparticles and fertilizer has non-significant effects on the consortium degradation potential. Moreover, fertilizer alone or in combination with AgNPs and consortium slows the rate of degradation of TPHs over a short period. Still, it subsequently accelerates the rate of degradation of TPHs, and a negligible amount remains at the end of the incubation period.