scholarly journals Enhanced Nitrogen Removal of Steel Rolling Wastewater by Constructed Wetland Combined with Sulfur Autotrophic Denitrification

2021 ◽  
Vol 13 (3) ◽  
pp. 1559
Author(s):  
Tao Zheng ◽  
Xiaohu Lin ◽  
Jingcheng Xu ◽  
Jie Ren ◽  
Danyan Sun ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Autotrophic Denitrification ◽  
Low Carbon ◽  
Treatment Technology ◽  
Steel Rolling ◽  
Iron And Steel ◽  
Structure Observation ◽  
Ecological Treatment ◽  
Sand And Gravel ◽  
Observation Results

Constructed wetlands (CWs), an ecological treatment technology, is suitable for advanced treatment, but has an unsatisfying denitrification performance for steel rolling wastewater with low C/N ratio. This study combined sulfur autotrophic denitrification (SAD) with conventional constructed horizontal subsurface flow wetlands to treat steel rolling wastewater, exploring the feasibility of applying SAD to enhance the denitrification performance of CWs. The reactor consists of two sections, one filled with manganese sand and gravel (HFC) and another filled with ceramic, sulfur, and lime (HFSAD). Results showed that HFC had a good performance on removing turbidity, DO, COD, and TP, while the average removal efficiency of total nitrogen (TN) in HFC was just 25.6%. On this basis, HFSAD could remove 45.6% of TN subsequently, whose denitrification rate was 4–6 times as high as that of HFC. Increasing hydraulic retention time could improve removal efficiency of contaminants in HFC and HFSAD in different degrees. The analysis of microbial community structure, observation results of fillers and monitored sulfate all provided proofs for the occurrence of SAD. CWs combined with SAD can be applied in the treatment of steel rolling wastewater with low carbon, which can provide reference for ecological wastewater treatment, water saving, and recycling in iron and steel enterprises.

Crystallographic Texture Control Helps Improve Pipeline Steel Resistance to Hydrogen-Induced Cracking

2010 ◽  
Author(s):  
V. Venegas ◽  
O. Herrera ◽  
F. Caleyo ◽  
J. M. Hallen ◽  
T. Baudin
Keyword(s):  
Grain Boundaries ◽  
Crystallographic Texture ◽  
Pipeline Steel ◽  
Low Carbon Steel ◽  
Rolling Process ◽  
Warm Rolling ◽  
American Petroleum Institute ◽  
Low Carbon ◽  
Steel Rolling ◽  
Hydrogen Induced Cracking

Low-carbon steel specimens, all within API (American Petroleum Institute) specifications, were produced following different thermomechanical paths. After austenization, the samples were rolled and recrystallized. The rolling process was carried out using different reduction-in-thickness degrees and finishing temperatures. The investigated steels showed similar microstructural features but differed considerably in their crystallographic textures and grain boundary distributions. After cathodic hydrogen charging, hydrogen-induced cracking (HIC) was detected in the hot-rolled recrystallized steels, whereas the cold and warm-rolled recrystallized steels proved resistant to this damage. Among the investigated specimens, the HIC-stricken show either the strongest {001}ND texture fiber, the smallest fraction of low-angle grain boundaries, or the weakest {111}ND (γ) texture fiber ({hkl}ND representing crystallographic orientations with {hkl} planes parallel to the steel rolling plane). In contrast, the HIC-resistant steels show the weakest {001}ND texture fiber, the largest fraction of low-angle grain boundaries, and the strongest γ fiber. These results support the hypothesis of this and previous works, that crystallographic texture control, through warm rolling schedules, helps improve pipeline steel resistance to hydrogen-induced cracking.

scholarly journals Does Emission Trading Improve Carbon Emission Efficiency of China’s Iron and Steel Industry? An Exploration Using a DEA-SBM and Difference-In-Differences Approach

2021 ◽  
Author(s):  
Xiping Wang ◽  
Sujing Wang
Keyword(s):  
Steel Industry ◽  
Carbon Emission ◽  
Emission Trading ◽  
Energy Structure ◽  
Iron And Steel Industry ◽  
Low Carbon ◽  
Difference In Differences ◽  
Iron And Steel ◽  
Emission Efficiency ◽  
The Impact

Abstract As an effective tool of carbon emission reduction, emission trading has been widely used in many countries. Since 2013, China implemented carbon emission trading in seven provinces and cities, with iron and steel industry included in the first batch of pilot industries. This study attempts to explore the policy effect of emission trading on iron and steel industry in order to provide data and theoretical support for the low-carbon development of iron and steel industry as well as the optimization of carbon market. With panel data of China’s 29 provinces from 2006 to 2017, this study adopted a DEA-SBM model to measure carbon emission efficiency of China’s iron and steel industry (CEI) and a difference-in-differences (DID) method to explore the impact of emission trading on CEI. Moreover, regional heterogeneity and influencing mechanisms were further investigated, respectively. The results indicate that: (1) China's emission trading has a significant and sustained effect on carbon abatement of iron and steel industry, increasing the annual average CEI by 12.6% in pilot provinces. (2) The policy effects are heterogeneous across diverse regions. Higher impacts are found in the western and eastern regions, whereas the central region is not significant. (3) Emission trading improves CEI by stimulating technology innovation, reducing energy intensity, and adjusting energy structure. (4) Economic level and industrial structure are negatively related to CEI, while environmental governance and openness degree have no obvious impacts. Finally, according to the results and conclusions, some specific suggestions are proposed.

scholarly journals Electrochemical redox treatment of denitrification in coastal secondary effluent using Ti/IrO2 anode

2021 ◽  
Author(s):  
Yaozong Zhang ◽  
Bo Pang
Keyword(s):  
Removal Efficiency ◽  
Treatment Plant ◽  
Chloride Ion ◽  
Ion Concentration ◽  
Secondary Effluent ◽  
Low Carbon ◽  
Cathodic Potential ◽  
Nitrate N ◽  
N Removal ◽  
Electrochemical Redox

Abstract In northern coastal industrial park, inlet of the wastewater treatment plant (WWTP) had the characteristics of low carbon source and high chloride ion concentration, which resulted in its poor biodegradability. In this case, the experiment explored an electrochemistral method to remove nitrogen. Cathodic potential, Ti/IrO2 was confirmed as the anode and − 1.6V was taken as the potential in order to remove nitrate-N. The findings include: when the initial chloride ion was 2000 and 3000 mg/L, the effect on the removal difference of nitrogen was slight. When the electrolysis time was 60 min, ammonia-N was removed completely, nitrite-N concentration kept 1mg/L approximately. The ammonia-N removal efficiency went up with the increasing cathodic potential, and was completely removed in different water samples, but nitrate-N removal showed an opposite result. The production amount of nitrite-N was the least at -1.6V. As the pH increased, ammonia-N and nitrate-N’s removal efficiency went up first and then down, the removal effect was the best at pH being 9, Nitrite-N was less influenced by pH. After optimizing the raw water sample, Nitrate-N and TN removal efficiency were significantly increased, but the nitrite-N almost kept constant.

scholarly journals Evaluation of a novel low-carbon to nitrogen- and temperature-tolerant simultaneously nitrifying–denitrifying bacterium and its use in the treatment of river water

RSC Advances ◽  
2018 ◽  
Vol 8 (48) ◽  
pp. 27417-27422 ◽  
Author(s):  
Peng Jin ◽  
Yinyan Chen ◽  
Zhanwang Zheng ◽  
Qizhen Du
Keyword(s):  
Low Temperature ◽  
River Water ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Simultaneous Nitrification And Denitrification ◽  
Low Carbon ◽  
High Nitrogen ◽  
Denitrifying Bacterium ◽  
Nitrification And Denitrification

A novel simultaneous nitrification and denitrification Klebsiella sp. exhibits high nitrogen removal efficiency under low-temperature and low C/N wastewater.

An iron-carbon-activated carbon and zeolite composite filter, anaerobic-aerobic integrated denitrification device for nitrogen removal in low C/N ratio sewage

2019 ◽  
Vol 80 (2) ◽  
pp. 223-231
Author(s):  
Yixuan Xie ◽  
Ajun Wan ◽  
Xingmin Wang ◽  
Hengjie Dong ◽  
Yunpeng Wu
Keyword(s):  
Activated Carbon ◽  
Nitrogen Removal ◽  
High Efficiency ◽  
Strong Shock ◽  
Autotrophic Denitrification ◽  
Low Carbon ◽  
Carbon Nitrogen Ratio ◽  
Nitrogen Ratio ◽  
Composite Filter ◽  
Zeolite Composite

Abstract In this study, we use an anaerobic-aerobic integrated denitrification (Fe/C-ZACID) device with an iron-carbon-activated carbon and zeolite composite filter to remove nitrogen from simulated low carbon-nitrogen ratio (C/N) sewage. The impacts of dissolved oxygen (DO) level, hydraulic retention time (HRT), C/N and nitrate recirculation ratio on denitrification performance were studied. The results show that when HRT was 6 h, DO was 3 ± 0.1 mg/L, influent C/N was 3, and nitrate recirculation ratio was 100%, and removal rates of 95% for ammonia and 85% for total nitrogen (TN) were achieved. A beaker comparison test demonstrated that this synergistic denitrification system included heterotrophic denitrification, physicochemical denitrification, iron autotrophic denitrification and hydrogen autotrophic denitrification, etc. The Fe/C-ZACID device has a high-efficiency nitrogen removal effect for low C/N ratio sewage and strong shock resistance, which provides technical support and a theoretical basis for advanced denitrification of rural domestic sewage.

Study of pyrite based autotrophic denitrification system for low-carbon source stormwater treatment

2020 ◽  
Vol 37 ◽  
pp. 101414 ◽  
Author(s):  
Yifan Chen ◽  
Zhiyu Shao ◽  
Zheng Kong ◽  
Li Gu ◽  
Junhua Fang ◽  
...  
Keyword(s):  
Carbon Source ◽  
Autotrophic Denitrification ◽  
Stormwater Treatment ◽  
Low Carbon

The ecological filter system for treatment of decentralized wastewater

2016 ◽  
Vol 74 (7) ◽  
pp. 1553-1560
Author(s):  
Kun Zhong ◽  
Yi-yong Luo ◽  
Zheng-song Wu ◽  
Qiang He ◽  
Xue-bin Hu ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Organic Pollutants ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Nitrogen And Phosphorus ◽  
Treatment Technology ◽  
Removal Rates ◽  
Carbon Nitrogen Ratio ◽  
Ecological Filter ◽  
Aerated Filter

A vertical flow constructed wetland was combined with a biological aerated filter to develop an ecological filter, and to obtain the optimal operating parameters: The hydraulic loading was 1.55 m3/(m2·d), carbon–nitrogen ratio was 10, and gas–water ratio was 6. The experimental results demonstrated considerable removal efficiency of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) in wastewater by the ecological filter, with average removal rates of 83.79%, 93.10%, 52.90%, and 79.07%, respectively. Concentration of NH4+-N after treatment met the level-A discharge standard of GB18918-2002. Compared with non-plant filter, the ecological filter improved average removal efficiency of COD, NH4+-N, TN, and TP by 13.03%, 25.30%, 14.80%, and 2.32%, respectively: thus, plants significantly contribute to the removal of organic pollutants and nitrogen. Through microporous aeration and O2 secretion of plants, the ecological filter formed an aerobic–anaerobic–aerobic alternating environment; thus aerobic and anaerobic microbes were active and effectively removed organic pollutants. Meanwhile, nitrogen and phosphorus were directly assimilated by plants and as nutrients of microorganisms. Meanwhile, pollutants were removed through nitrification, denitrification, filtration, adsorption, and interception by the filler. High removal rates of pollutants on the ecological filter proved that it is an effective wastewater-treatment technology for decentralized wastewater of mountainous towns.

scholarly journals Electron beam treatment of simulated marine diesel exhaust gases

Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 689-695 ◽  
Author(s):  
Janusz Licki ◽  
Andrzej Pawelec ◽  
Zbigniew Zimek ◽  
Sylwia Witman-Zając
Keyword(s):  
Electron Beam ◽  
Removal Efficiency ◽  
Diesel Engines ◽  
Diesel Exhaust ◽  
Irradiation Dose ◽  
Treatment Technology ◽  
Gas Treatment ◽  
Exhaust Gases ◽  
Marine Diesel ◽  
Removal Efficiencies

Abstract The exhaust gases from marine diesel engines contain high SO2 and NOx concentration. The applicability of the electron beam flue gas treatment technology for purification of marine diesel exhaust gases containing high SO2 and NOx concentration gases was the main goal of this paper. The study was performed in the laboratory plant with NOx concentration up to 1700 ppmv and SO2 concentration up to 1000 ppmv. Such high NOx and SO2 concentrations were observed in the exhaust gases from marine high-power diesel engines fuelled with different heavy fuel oils. In the first part of study the simulated exhaust gases were irradiated by the electron beam from accelerator. The simultaneous removal of SO2 and NOx were obtained and their removal efficiencies strongly depend on irradiation dose and inlet NOx concentration. For NOx concentrations above 800 ppmv low removal efficiencies were obtained even if applied high doses. In the second part of study the irradiated gases were directed to the seawater scrubber for further purification. The scrubbing process enhances removal efficiencies of both pollutants. The SO2 removal efficiencies above 98.5% were obtained with irradiation dose greater than 5.3 kGy. For inlet NOx concentrations of 1700 ppmv the NOx removal efficiency about 51% was obtained with dose greater than 8.8 kGy. Methods for further increase of NOx removal efficiency are presented in the paper.

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