Treatment of Petroleum Drill Cuttings Using Stabilization/Solidification Method by Cement and Modified Clay Mixes

High organic content in petroleum drill cuttings is a substantial obstacle which hinders cement hydration and subsequently decreases the clean-up efficiency of the stabilization/solidification (S/S) process. In this study, a modified clayey soil (montmorillonite with low to moderate polarity) was used as an additive to cement. Because of its high adsorption capacity, the clay is capable of mitigating the destructive role of organic materials and preventing their interference with the hydration process. Mixes containing different ratios of cement, waste and modified clay were prepared and tested for their mechanical and chemical characteristics. Total petroleum hydrocarbons (TPH) and Pb content of the samples were analyzed as well. For this purpose, the mixes were subjected to unconfined compressive strength (UCS) and toxicity characteristic leaching procedure (TCLP) tests. The results indicated that the specimens with 28-day curing time at a cement/waste ratio of 25% or higher (w/w) and 10% modified clay (w/w) met the Environmental Protection Agency (EPA) criterion for compressive strength. Moreover, a reduction of 94% in the leaching of TPH was observed with the specimens undergoing the TCLP with a cement/waste ratio of 30% (w/w) and a clay/waste ratio of 30% (w/w). Finally, the specimens with 30% cement/waste and 10% clay/waste ratios showed the least concentration (6.14%) of leached Pb

Geological and fluid inclusion studies in the Muteh gold district, Sanandaj-Sirjan zone, Isfahan Province, Iran

Metamorphic rocks of the Sanandaj-Sirjan zone host the Muteh gold mining district. The gold occurrences are in northwest-striking and northeast-dipping normal faults crosscutting the regional ductile pattern of the host rocks. This faulting is possibly related to a Tertiary extensional uplift event. The hydrothermal alteration assemblage quartz-muscovite-pyrite-carbonate-albite overprints the metamorphic assemblage. Gold is associated with pyrite.Fluid inclusion data suggest that gold deposition is related to mixing between a regional C0₂-bearing saline fluid and a dilute fluid, possibly of meteoric origin

A non-threshold model to estimate carcinogenic risk of nitrate-nitrite in drinking water

Understanding nitrate–nitrite (3−2) levels in drinking water and associated non-carcinogenic and carcinogenic health risks are essential to protect public health safety. The non-carcinogenic risk assessment of 3–2 in drinking water has been well documented, however, there remains a knowledge gap in understanding and quantification of the carcinogenic risk of 3–2. This study develops a non-threshold–based model for estimation of carcinogenic risk of 3–2 ingested through drinking water for a densely populated urban area with a case study of Tehran's potable water (TPW). In this regard, 200 tap water samples from different parts of the city were taken in wet (May 2018) and dry (October 2018) periods to determine 3– concentration in the TPW and the associated health risks across different grounds of end-users. Sampling results reveal higher concentrations of 3– during the dry period, which can be associated to the significant contribution of nitrogen–rich groundwater in supplying the city's water demands during the dry period. Findings suggest concerns associated with the non-carcinogenic risk of 3– in the TPW, especially for children. More than 55% of the samples taken during the dry period show a positive carcinogenic risk for different groups of end-users (68% for men, 72% for women, and 56% for children) whilst just 8% of the samples are deemed unsafe with regards to the permissible level in drinking water, i.e. 50 mg/L. Approximately, 45% of the samples taken during the wet period show a positive carcinogenic risk for adults whilst the maximum concentration of was about 23 mg/L, i.e. two times less than the permissible level in drinking water. The findings emphasize on the necessity of reducing the permissible level of in drinking water, set out by the existing water quality standards, to safeguard public health against the carcinogenic risks. The model developed within this study recommends the urgent need for reduction of level in Tehran's water resources to protect public health of over 13 M population who incessantly use the TPW