ABSTRACT
The operation of the Cansolv tail gas treatment device in natural gas plants generates acidic and alkaline wastewater from the venturi unit and amine purification unit (APU), respectively. The APU wastewater is complex in composition and contains hard-to-degrade organic matter, which can adversely impact the normal functioning of the water treatment system. This study assesses the efficacy of three ozone-based advanced oxidation processes (ozone (O3), ozone/hydrogen peroxide (O3/H2O2), and ozone/Fenton (O3/Fenton)) for treating Cansolv wastewater, with chemical oxygen demand (COD) and total organic carbon (TOC) serving as indicators of organic degradation. The findings demonstrate that all three processes effectively eliminate coloration and reducible sulfur, with O3/Fenton exhibiting superior performance in removing organic substances. The treated wastewater has a clarified light-yellow appearance with residual COD levels at 43 mg L-1. Under the optimum Fenton oxidation conditions (initial pH 5, H2O2 dosage 97.8 mmol L-1, FeSO4·7H2O dosage 550 mg L-1), average TOC and COD removal rates reached 50% and 97%, respectively. After a treatment duration of 60 minutes, the wastewater demonstrated an enhanced membrane-specific flux, confirming the effectiveness of the O3/Fenton oxidation process in mitigating membrane fouling while ensuring the stable operation of the wastewater treatment system.
ABSTRACT
Shale gas flowback water (SGFW), which is an inevitable waste product generated after hydraulic fracturing during development, poses a severe threat to the environment and human health. Managing high-salinity wastewater with complex physicochemical compositions is critical for ensuring environmental sustainability of shale gas development. Desalination processes have been recommended to treat SGFW to adhere to the discharge limits. However, organic fouling has become a significant concern in the steady operation of desalination processes, and the effective removal of organic compounds is challenging. This study aimed to develop an effective oxidation method to mitigate membrane fouling in real SGFW treatment process. It adopted the peroxymonosulfate (PMS)/ferrate (Fe(VI)) process, involving both free and non-free radical pathways that can alleviate the negative effects of high-salinity environments on oxidation. The operating parameters were optimized and removal effects were examined, while the synergistic oxidation mechanism and organic conversion of the PMS/Fe(VI) process were also analyzed. The results showed that the PMS/Fe(VI) process exhibited a synergistic effect compared with the PMS and Fe(VI) processes alone, with a total organic carbon (TOC) removal efficiency of 46.8% under optimal reaction conditions in real SGFW. In the Fe(VI)/PMS process, active species such as Fe(V)/Fe(IV), ·OH, and SO4-· were jointly involved in the oxidation of organic matter. Additionally, 99.5% of the total suspended solids and 95.2% of Ba2+ in the SGFW were removed owing to the formation of a coagulant (Fe3+) and SO42- during the reaction. Finally, an ultrafiltration membrane fouling experiment proved that oxidation processes can increase the membrane-specific flux and alleviate fouling resistance. This study can serve as a reference for the design of real SGFW treatment processes and is significant for the environmental management of shale gas development.
Subject(s)
Water Pollutants, Chemical , Water Purification , Humans , Natural Gas , Membranes, Artificial , Water Purification/methods , Oxidation-ReductionABSTRACT
Polyphenols, also known as phenolic compounds, are chemical substances containing aromatic rings as well as at least two hydroxyl groups. Natural phenolic compounds exist widely in plants, which protect plants from ultraviolet radiation and other insults. Phenolic compounds have superior pharmacological and nutritional properties (antimicrobial, antibacterial, antiviral, anti-sclerosis, antioxidant, and anti-inflammatory activities), which have been paid more and more attention by the scientific community. Phenols can protect key cellular components from reactive free radical damage, which is mainly due to their property to activate antioxidant enzymes and alleviate oxidative stress and inflammation. It can also inhibit or isolate reactive oxygen species and transfer electrons to free radicals, thereby avoiding cell damage. It has a regulatory role in glucose metabolism, which has a promising prospect in the prevention and intervention of diabetes. It also prevents cardiovascular disease by regulating blood pressure and blood lipids. Polyphenols can inhibit cell proliferation by affecting Erk1/2, CDK, and PI3K/Akt signaling pathways. Polyphenols can function as enhancers of intrinsic defense systems, including superoxide dismutase (SOD) and glutathione peroxidase (GPX). Simultaneously, they can modulate multiple proteins and transcription factors, making them promising candidates in the investigation of anti-cancer medications. This review focuses on multiple aspects of phenolic substances, including their natural origins, production process, disinfection activity, oxidative and anti-inflammatory functions, and the effects of different phenolic substances on tumors.
Subject(s)
Antioxidants , Neoplasms , Humans , Antioxidants/pharmacology , Antioxidants/therapeutic use , Antioxidants/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Ultraviolet Rays , Oxidative Stress , Phenols/pharmacology , Phenols/therapeutic use , Neoplasms/drug therapy , Polyphenols/pharmacology , Free Radicals/metabolism , Inflammation/drug therapy , Anti-Inflammatory Agents/pharmacology , Anti-Inflammatory Agents/therapeutic use , Anti-Inflammatory Agents/chemistryABSTRACT
BACKGROUND: Connective tissue growth factor (CTGF) has diagnostic value for pulmonary arterial hypertension (PAH) associated with congenital heart disease (CHD) in children; however, its value in adult patients remains unclear. This study evaluated CTGF as a biomarker in adult PAH-CHD patients.MethodsâandâResults: Based on mean pulmonary artery pressure (mPAP), 56 CHD patients were divided into 3 groups: without PAH (W; mPAP <25 mmHg; n=28); mild PAH (M; mPAP 25-35 mmHg; n=18); and moderate and severe PAH (H; mPAP ≥35 mmHg; n=10). The control group consisted of 28 healthy adults. Plasma CTGF and B-type natriuretic peptide (BNP) concentrations were determined. Plasma CTGF concentrations were higher in the H and M groups than in the W and control groups, and were higher in the H than M group. Plasma CTGF concentrations were positively correlated with pulmonary artery systolic pressure (PASP), mPAP, and pulmonary vascular resistance, and negatively correlated with mixed venous oxygen saturation. CTGF, BNP, red blood cell distribution width, and World Health Organization Class III/IV were risk factors for PAH in CHD patients, and CTGF was an independent risk factor for PAH-CHD. The efficacy of CTGF in the diagnosis of PAH was not inferior to that of BNP. CONCLUSIONS: CTGF is a biomarker of PAH associated with CHD. It can be used for early diagnosis and severity assessment in adult patients with CHD-PAH.
Subject(s)
Heart Defects, Congenital , Hypertension, Pulmonary , Pulmonary Arterial Hypertension , Child , Humans , Adult , Pulmonary Arterial Hypertension/diagnosis , Pulmonary Arterial Hypertension/etiology , Connective Tissue Growth Factor , Heart Defects, Congenital/complications , Heart Defects, Congenital/diagnosis , Hypertension, Pulmonary/diagnosis , Hypertension, Pulmonary/etiology , Familial Primary Pulmonary Hypertension/complications , Biomarkers , Natriuretic Peptide, BrainABSTRACT
Offshore water-based drilling cuttings (OWDC) are by-products of offshore oil-well drilling, whose effective management has become an urgent environmental and engineering issue. This study investigated the feasibility of recycling OWDC from the Bohai oilfield in China as a raw material for manufacturing lightweight aggregates (LWA). The effects of OWDC content (0-50%), preheating temperature (300-500 °C), and sintering temperature (1050-1200 °C) on the physical-mechanical performance of the resulting LWA were investigated through single-factor experiments. The microstructural and expansion mechanism analyses were determined based on X-ray diffraction analysis, scanning electron microscopy, and energy-dispersive X-ray spectrometric microanalysis. The results showed that under the optimum preparation conditions (mass ratio of OWDC and fly ash at 50:50, preheating at 400 °C for 30 min, and sintering at 1150 °C for 30 min), the OWDC-based LWA could meet the requirements of Chinese standard GB/T 17431.1-2010. The incorporation of OWDC lowered the aggregate melting points and promoted dense structure formation inside the aggregates due to the presence of flux agents (e.g., Na2O and K2O). Besides, OWDC additions promoted the formation of the liquid phase and gases inside the pellets, which was beneficial to the expansion behavior and lightweight performance of the aggregates. However, OWDC also had a negative effect on the compressive strength of the aggregates owing to the formation of enlarged pores. Furthermore, the results of the environmental performance tests indicated that the LWA were safe for the environment. This study provides a reference for recycling water-based drilling cuttings from offshore oilfields and contributes to the circular economy.
Subject(s)
Oil and Gas Fields , Water , Temperature , Coal Ash/chemistry , ChinaABSTRACT
This study determined the environmental impacts of three recycling pathways for water-based drilling cuttings (WDC), namely cement, sintered bricks, and non-sintered bricks, based on the life cycle assessment (LCA) method. A life cycle inventory was developed with based on the resource utilization of 1t drilling cuttings as the functional unit, and a sensitivity analysis was conducted to identify the essential materials and energy consumption. The results showed that the sequence of the environmental impact index for the three recycling pathways was cement, non-sintered brick and sintered brick. Primary energy demand and direct emissions were the main reasons for this difference. Direct emissions, electricity, and binder were the largest contributors to the inventory of cement, sintered bricks, and non-sintered bricks, accounting for 54%, 33.4%, and 62.1% of the environmental impact burden, respectively. Furthermore, a 5% reduction in direct emissions, electricity, and binder decreased the integrated impact index by approximately 2.67%, 3.04%, and 3.38% for cement, sintered bricks, and non-sintered bricks, respectively. Based on the LCA results, strategies for reducing emissions and conserving energy were proposed. These results provide a useful reference for creating a sustainable system for recycling water-based drilling cuttings.
Subject(s)
Natural Gas , Water , Animals , China , Construction Materials , Glass Ionomer Cements , Life Cycle StagesABSTRACT
Large amounts of water-based drilling cuttings (WDC) would be generated during the drilling of shale gas wells, which would occupy land resources and pose significant threat to soil and groundwater environment. The aim of this study was to assess the feasibility of using WDC as a replacement of natural clay to prepare sintered bricks. To determine the optimum preparation condition, the weight loss on ignition, bulk density, water absorption, and compressive strength of the samples were tested. Meanwhile, the environmental performance of the final products was evaluated and micro-analysis was conducted via X-ray diffraction and scanning electron microscopy. The results showed that using WDC to manufacture sintered bricks was technically feasible, but the physical mechanical performance would significantly decrease with the increase of the replacement ratio because of the presence of less silica and excessive calcium. The addition of waste glass and fly ash could promote the generation of molten glassy phase and form the crystal particle bonding structure, which would contribute to the physical-mechanical performance of WDC sintered bricks. Some mineral components in raw materials decomposed and formed minerals with better thermal stability during the sintering process. Under the optimum preparation conditions (mass ratio of WDC: waste glass: fly ash at 40:20:40, sintering temperature at 900 °C, and insulation time at 2 h), the physical-mechanical and environmental performance of WDC sintered bricks could meet the requirements of corresponding Chinese standards and ASTM standards. Thus, in this study, an effective solution to recycle WDC from shale gas development is provided.
Subject(s)
Natural Gas , Water , China , Coal Ash , RecyclingABSTRACT
The disposal of flowback water is recognized as a key issue for the sustainable shale gas development and discharge after reasonable treatment is considered as a feasible pathway. One of the challenges during treatment is the severe mineral scaling potential in reverse osmosis desalination, especially with high amounts of Ca2+, Mg2+, Ba2+ and Sr2+ in flowback water. In this study, precipitation behaviors of Ca2+, Mg2+, Ba2+ and Sr2+ during traditional chemical softening was evaluated so as to achieve optimal chemical dosage. Both jar tests and OLI Stream Analyzer simulation revealed that the main precipitates were CaCO3, SrCO3 and BaSO4 during Na2CO3 addition, and Ba2+ could not be removed efficiently by Na2CO3 unless a high dosage was applied since Ba2+ would react after the precipitation of Ca2+ and Sr2+. Reverse Osmosis System Analysis simulation indicated that Ba2+ was a concern because Ba2+ would form tenacious BaSO4 scale on the reverse osmosis membranes. Finally, the Na2SO4-NaOH-Na2CO3 process was proposed for chemical softening as it has a high removal efficiency and low chemical cost. Overall, this study presents an effective chemical softening method and OLI Stream Analyzer could serve as a reliable tool for the calculation, which would finally improve the design and operation of shale gas flowback water treatment.
Subject(s)
Natural Gas , Rivers , China , Wastewater , WaterABSTRACT
To elucidate the role of autophagy in ischemia-reperfusion injury (IRI) and determine whether glycogen synthase kinase-3ß (GSK-3ß) plays an important role in autophagy, a donors of cardiac death (DCD) liver transplantation model was established to observe the expression of GSK-3ß and autophagy in hepatocytes during liver IRI. Immunohistochemical staining and western blotting were used to detect expression of the autophagy markers, LC3 and p62, as well as study the expression of GSK-3ß and AMPK. Serum enzymology changes were analyzed at different times after liver transplantation. Hypoxia-reoxygenation methods were used to mimic the process of ischemia-reperfusion injury in cultured hepatocytes. In DCD liver transplantation with a prolonged reperfusion time, LC3 expression increased, whereas p62 decreased. GSK-3ß and AMPK expression in the transplanted liver tissue were consistent with changes in autophagy, ALT, and AST. In summary, inactive GSK-3ß reduced liver IRI, promoted hepatocyte autophagy, and improved hepatocyte activity. Therefore, GSK-3ß may regulate autophagy through the AMPK-mTOR pathway.
ABSTRACT
Treated municipal wastewater (MWW) is recognized as a significant potential source of cooling water for power generation. One of the key challenges for the successful use of the effluent from wastewater treatment facilities for cooling is the potential for significant mineral scaling when the raw water is concentrated as much as 4-6 times in recirculating cooling systems. Previous bench- and pilot-scale tests have shown that commonly used phosphorus- and polymer- based scaling inhibitors are ineffective when secondary-treated municipal wastewater (MWW) is used as make-up. In this study, two types of tertiary-treated municipal wastewaters, namely secondary-treated MWW with pH adjustment (MWW_pH) and secondary-treated MWW subjected to nitrification and sand filtration (MWW_NF) were evaluated as the sole source of make-up water for recirculating cooling systems. Both laboratory studies and pilot-scale tests revealed that adjusting the pH to 7.8 could reduce the mineral scaling rate by more than 80% without causing any significant corrosion problems. In contrast to MWW, where calcium carbonate was the dominant scaling mineral, the main component of mineral scale in MWW_pH was calcium phosphate. Both static and dynamic bench-scale tests indicated that scaling would not be a significant concern when MWW_NF is used as the make-up water in recirculating cooling systems operated at 4-6 cycles of concentration (CoC). Extended pilot-scale studies confirmed that MWW_NF is suitable makeup water for power plant cooling systems and that no anti-scaling chemicals would be required.
Subject(s)
Cities , Cold Temperature , Minerals/chemistry , Waste Disposal, Fluid , Water Purification/methods , Batch Cell Culture Techniques , Calcium/analysis , Chemical Precipitation , Hydrogen-Ion Concentration , Microscopy, Electron, Scanning , Pennsylvania , Phosphates/analysis , Pilot Projects , Solutions , X-Ray DiffractionABSTRACT
The objective of this study was to assess the feasibility of solidification of municipal solid waste incinerator (MSWI) fly ash with circulation fluidized bed combustion (CFBC) fly ash, which is unsuitable as a cement replacement due to its high amounts of carbon, lime and anhydrite. The solidification process was conducted on samples prepared from MSWI fly ash, binders (cement clinkers and CFBC fly ash were mixed at two replacement ratios) and water (water/solid weight ratio = 0.4), among which the MSWI fly ash replaced each binder at the ratio of 0, 20, 40, 60 and 80% by dry weight. The samples were subjected to compressive strength tests and Toxicity Characteristic Leaching Procedure and the results showed that all solidified MSWI fly ash can meet the landfill standard imposed by US EPA after 28 days of curing. Micro-analysis (X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectrophotometry) revealed that the main hydrate products were C-S-H gel and ettringite, which have a positive effect on heavy metals retention. Therefore, this method provides a possibility to achieve a cheap and effective solution for MSWI fly ash management and use for CFBC fly ash.
Subject(s)
Carbon/chemistry , Coal/analysis , Incineration , Particulate Matter/chemistry , Cities , Coal Ash , Environmental Pollution/prevention & control , Metals, Heavy/chemistry , Microscopy, Electron, Scanning , X-Ray DiffractionABSTRACT
The chemical composition and the leachability of heavy metals in municipal solid waste incinerator (MSWI) fly ash were measured and analysed. For the leachability of unstabilized MSWI fly ash it was found that the concentrations of Pb and Cr exceeded the leaching toxicity standard. Cementitious solidification of the MSWI fly ash by Na2SiO3-activated ground granulated blast-furnace slag (NS) was investigated. Results show that all solidified MSWI fly ash can meet the landfill standards after 28 days of curing. The heavy metals were immobilized within the hydration products such as C-S-H gel and ettringite through physical encapsulation, substitution, precipitation or adsorption mechanisms.