Characterization of a novel marine aerobic denitrifier Vibrio spp. AD2 for efficient nitrate reduction without nitrite accumulation

Environmental Science and Pollution Research - Aerobic denitrifiers have the potential to reduce nitrate in polluted water under aerobic conditions. A salt-tolerant aerobic denitrifier was newly...     

管式法高压聚乙烯装置的道化学火灾爆炸危险指数评价

运用道化学火灾爆炸危险指数评价方法,对Quantum管式法高压聚乙烯装置中多次出现泄漏火灾的聚合单元进行评价。对照装置实际分析了防火防爆缺陷因子,提出完善聚合单元的防火防爆措施。     

Effect of preparation methods on the performance of CuFe-SSZ-13 catalysts for selective catalytic reduction of NOx with NH3

CuFe-SSZ-13 catalyst showed excellent performance in the selective catalytic reduction of NO_x with NH₃ (NH₃-SCR) for diesel engine exhaust purification. To investigate the effect of preparation methods on NH₃-SCR performance, Fe was loaded into one-pot synthesized Cu-SSZ-13 catalysts through solid-state ion-exchange (SSIE), homogeneous deposition precipitation (HDP) and liquid ion-exchange (IE), respectively. Three CuFe-SSZ-13 catalysts showed similar SO₂ resistance, which was better than that of Cu-SSZ-13. The improvement was attributed to the protection of Fe species. Hydrothermal stability of three CuFe-SSZ-13 catalysts was significantly different, which was attributed to the state of active species caused by different preparation methods. Compared with the other two catalysts, more active species existed inside the zeolite pores of CuFe-SSZ-13_SSIE. During hydrothermal aging, the aggregation of these active species in the pores caused the collapse of catalyst structure, ultimately leading to the deactivation of CuFe-SSZ-13_SSIE. In contrast, Fe species was dispersed better on the surface over CuFe-SSZ-13_IE, enhancing the hydrothermal stability of catalysts. Consequently, Fe loading effectively improved the resistance of SO₂ and H₂O over Cu-SSZ-13. For CuFe-SSZ-13, large amounts of active species located inside the zeolite pores are not beneficial for the hydrothermal stability.     

印染废水混凝脱色技术的分子结构基础

印染废水的混凝脱色效果取决于染料分子的分子结构及其在水中的分子分散状态和染料的染色机制。大量研究结果表明，所选用的染料分子的分子结构决定了印染废水混凝脱色技术的混凝机制和混凝效果，合成絮凝剂与选择絮凝剂应充分考虑染料分子的分子结构与空间构型。     

Carbonaceous and nitrogenous disinfection byproduct precursor variation during the reversed anaerobic–anoxic–oxic process of a sewage treatment plant

Disinfection byproduct(DBP)precursors in wastewater during the reversed anaerobic–anoxic–oxic(A~2/O)process,as well as their molecular weight(MW)and polarity-based fractions,were characterized with UV scanning,fluorescence excitation emission matrix,Fourier transform infrared and nuclear magnetic resonance spectroscopy.Their DBP formation potentials(DBPFPs)after chlorination were further tested.Results indicated that the reversed A~2/O process could not only effectively remove the dissolved organic carbon(DOC)and dissolved total nitrogen in the wastewater,but also affect the MW distribution and hydrophilic–hydrophobic properties of dissolved organic matter(DOM).The accumulation of low MW and hydrophobic(HPO)DOM was possibly due to the formation of soluble microbial product-like(SMP-like)matters in the reversed A~2/O treatment,especially in the anoxic and aerobic processes.Moreover,DOM in the wastewater displayed a high carbonaceous disinfection byproduct formation potential(C-DBPFP)in the fractions of MW100 k Da and MW5 k Da,and revealed an increasing tendency of nitrogenous disinfection byproduct formation potential(N-DBPFP)with decrease of MW.For polarity-based fractions,the HPO fraction of wastewater showed significantly higher C-DBPFP and N-DBPFP than hydrophilic and transphilic fractions.Therefore,although the reversed A~2/O process could remove most DBP precursors by DOC reduction,it led to the enhancement of DBPFP with the formation and accumulation of low MW and HPO DOM.In addition,strong correlations between C-DBPFPs and SUVA,and between N-DBPFPs and DON/DOC,were observed in the wastewater,which might be helpful for DBPFP prediction in wastewater and reclaimed water chlorination.     

Insights into sludge granulation during anaerobic treatment of high-strength leachate via a full-scale IC reactor with external circulation system

In this study, a full-scale internal circulation(IC) reactor coupled with an external circulation system was developed to treat high-strength leachate from a municipal solid waste(MSW)incineration plant, in which anaerobic sludge granulation was intensively investigated. Results showed that the IC reactor achieved excellent treatment performance under high organic loading rates(OLR) of 21.06–25.16 kg chemical oxygen demand(COD)/(m3? day). The COD removal efficiency and biogas yield respectively reached 89.4%–93.4% and 0.42–0.50 m3/kg COD.The formation of extracellular polymeric substances(EPS) was closely associated with sludge granulation. Protein was the dominant component in sludge EPS, and its content was remarkably increased from 21.6 to 99.7 mg/g Volatile Suspended Solid(VSS) during the reactor operation. The sludge Zeta potential and hydrophobicity positively correlated with the protein/polysaccharide ratio in EPS, and they were respectively increased from-26.2 m V and 30.35% to-10.6 m V and 78.67%, which was beneficial to microbial aggregation. Three-dimensional fluorescence spectroscopy(3 D-EEM) and Fourier transform infrared spectroscopy(FT-IR)analysis further indicated the importance of protein-like EPS substances in the sludge granulation. Moreover, it was also found that the secondary structures of EPS proteins varied during the reactor operation.     

露天采矿过程粉尘产生环节及污染治理措施分析研究

粉尘是露天采矿过程的主要污染物之一,露天采矿中粉尘要达到环保要求,需要从生产过程中的凿岩、爆破、装卸、运输、堆存各环节进行污染控制.采用对上述各生产环节中的粉尘产生原理进行分析的方法,找出各个生产环节粉尘的主要产生点,通过对比前人在各个生产环节粉尘控制的研究成果,找出控制粉尘产生的主要影响因素,总结出露天采矿中各个环节上技术经济上最有效的粉尘防治措施,为露天矿山开采污染防治提供系统的解决方案.通过对前人研究成果的总结,汇总形成一套完善的粉尘控制方案.