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Petroleum Origin and Generation
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
Geochemical oxidation/reduction reactivity plays a role in source rock. Oxic (presence of oxygen) conditions enhance the destruction of organic matter. A geochemical anoxic reducing environment (absence of oxygen) favors the preservation of TOC. The rate of degradation of organic matter is reduced in conditions of deficient/absent oxygen. High contents of TOC are found in stagnant, silted basins in anoxic conditions. Quantitatively oxidation/reduction activity is defined by the relative amounts of ferric (Fe+++) and ferrous (Fe++) ions in the environment. A high Fe+++/Fe++ ratio indicates high oxidation, and a low ratio refers to a reducing environment. A geochemical basin with a Fe+++/F++ ratio of 10 corresponds to 0.25% TOC. As the ratio progressively drops, the TOC increases accordingly.
Organics, Salts, Metals, and Nutrient Removal
Published in David H.F. Liu, Béla G. Lipták, Wastewater Treatment, 2020
R. David Holbrook, Sun-Nan Hong, Derk T.A. Huibers, Francis X. McGarvey, Chakra J. Santhanam
Part a in Figure 8.4.4 is a schematic representation of the A/O process. The unique feature of this aerobic (oxic) activated-sludge process is an anaerobic (both oxygen- and nitrate-deficient) zone at the influent end of this process. The anaerobic and aerobic zones are each divided into several equally sized compartments. Influent wastewater and return activated sludge (RAS) are fed to the first compartment of the anaerobic zone. Typically, either centrally mounted or submersible mixers provide gentle mixing in the anaerobic zone. Wastewater treatment facilities can use various aeration methods, such as fine-bubble diffusers, surface mechanical aerators, and oxygen aeration to meet the oxygen demands in the oxic zone.
Industrial Ecology for Waste Minimization, Utilization, and Treatment
Published in Stanley E. Manahan, Environmental Chemistry, 2022
Oxic (aerobic) waste treatment processes utilize oxic bacteria and fungi that require molecular oxygen, O2. These processes are often favored by microorganisms, in part because of the high energy yield obtained when molecular oxygen reacts with organic matter. Oxic waste treatment is well adapted to the use of an activated sludge process. It can be applied to hazardous wastes such as chemical process wastes and landfill leachates. Some systems use powdered activated carbon as an additive to absorb organic wastes that are not biodegraded by microorganisms in the system.
Compositional nature and geochemical implications of acidic and neutral NSO compounds in oils from the Baiyun Sag, Pearl River Mouth Basin, China
Published in Petroleum Science and Technology, 2023
Wenmin Jiang, Liping Yuan, Yun Li, Chao Yang, Bin Jiang, Yongqiang Xiong
In this study, the acidic and neutral NSO compounds in oils from the Baiyun Sag in the PRMB were characterized by negative ion ESI-FT-ICR-MS. These oils were dominated by oxygen-containing heteroatomic species, implying that they were sourced from organic matter deposited in oxic, freshwater lake settings. The oils from different structural belts exhibit obvious differences in the general compositions and distributions of NSO compounds and some special species (i.e., N1, O2, N1Oy), which would be used for oil-oil correlations. Heteroatom-based indices further revealed that these oils were sourced from hydrocarbon generation sag (i.e., MSS, ESS) and migrated to the sag margin or adjacent uplift (i.e., PLU) with their thermal maturity decreasing. Thus, the uplift in the southwest Baiyun Sag, which is close to MSS and has a low exploration level, would be a favorable petroleum exploration district. This work provides novel insights into the origin and evolution of crude oils and orients future exploration campaigns in the Baiyun Sag.
Influencing factors analysis for drinking water steel pipe pitting corrosion using artificial neural network
Published in Urban Water Journal, 2023
Kibum Kim, Heechang Kang, Taehyeon Kim, David Thomas Iseley, Jaeho Choi, Jayong Koo
Rajani and Makar (2000) took factors related to soil pH, soil resistivity, and the aeration constant into account when developing an exponential model to estimate the maximum pitting corrosion depth. Using the oxidation-reduction reaction of iron under oxic and anoxic conditions, Sarin et al. (2004) derived results showing that oxygen-related factors, such as the water content and concentration of oxygen compounds in the soil, affect the corrosion of metal pipes. Peterson and Melchers (2012) concluded that the water-related environment, under wet conditions, has the greatest influence on external corrosion. This is similar to the results presented by Romanoff (1957) and is evidenced by the tendencies of metal loss and large pitting corrosion growth in clay soil, which contains the most water (Petersen and Melchers 2019). Researchers have also found that the type and compaction of the soil are important factors affecting corrosion (Melchers, Petersen, and Wells 2019).
Marine depositional signatures of the Aptian Oceanic Anoxic Events in the Eastern Tethys, Lower Indus Basin, Pakistan
Published in Australian Journal of Earth Sciences, 2022
S. Khan, D. Kroon, B. Wadood, S. Ahmad, X. Zhou
Bottom current activity and clastic influx show positive correlation during OAE1a and OAE1b (Figure 9), while a negative correlation exists between oxygen enrichment and bottom current activity. Sinking oxic water may have reworked clastic sediments through traction and gravity processes. High dissolved oxygen in oxic surface water may have been diluted by dysoxic–anoxic conditions after sinking to the oxygen minimum resulting in anoxic conditions prevailing throughout the Aptian. The preservation of carbonate sediments throughout the OAE1a indicates absence of ocean acidification at least in this part of the Tethys. It further suggests that the acidity-induced carbonate crisis during OAE1a and OAE1b elsewhere may have been caused by methane outbursts from the ocean floors (e.g. Beerling & Berner, 2002). Such outbursts may not have occurred in this southern part of the ocean.