煤粒度和煤浆浓度对微生物法煤炭脱硫的影响

本文探讨了煤粒度和煤浆浓度对微生物脱硫的影响。实验结果表明,煤粒度越小,煤的脱硫率越高,小于0.054mm粒径的煤样(煤浆浓度10％),微生物在12天时间内,可脱除44.1％左右的硫,使煤的总含硫量从2.55％降到1.425％;浓度为10％的煤浆(粒径0.073—0.088mm)脱硫效果最好,微生物在12天时间内,可脱除38.9％左右的硫,使煤的总含硫量从2.55％降到1.558％。从而确定出微生物法煤炭脱硫工艺的最佳粒径要求和煤浆浓度条件。     

填料技术在废水生物处理中的应用和发展

填料技术是生物膜反应器的核心部分。本文阐述了填料在废水生物处理中的作用,讨论了理想填料必须具备的4项条件,介绍了目前国内外应用较广的几种主要填料的工艺特点及其规格参数,并对它们的性能进行了比较,最后简要分析了填料技术研究开发的动向。      

Occurrence and microbial degradation of phthalate esters in Taiwan river sediments

Concentrations and microbial degradation rates were measured for eight phthalate esters (PAEs) found in 14 surface water and six sediment samples taken from rivers in Taiwan. The tested PAEs were diethyl phthalate (DEP), dipropyl phthalate (DPP), di-n-butyl phthalate (DBP), diphenyl phthalate (DPhP), benzylbutyl phthalate (BBP), dihexyl phthalate (DHP), dicyclohexyl phthalate (DCP), and di-(2-ethylhexyl) phthalate (DEHP). In all samples, concentrations of DEHP and DBP were found to be higher than the other six PAEs. DEHP concentrations in the water and sediment samples ranged from ND to 18.5 μg/l and 0.5 to 23.9 μg/g, respectively; for DBP the concentration ranges were 1.0–13.5 μg/l and 0.3–30.3 μg/g, respectively. Concentrations of DHP, BBP, DCP and DPhP were below detection limits. Under aerobic conditions, average degradation half-lives for DEP, DPP, DBP, DPhP, BBP, DHP, DCP and DEHP were measured as 2.5, 2.8, 2.9, 2.6, 3.1, 9.7, 11.1 and 14.8 days, respectively; under anaerobic conditions, respective average half-lives were measured as 33.6, 25.7, 14.4, 14.6, 19.3, 24.1, 26.4 and 34.7 days. In other words, under aerobic conditions we found that DEP, DPP, DBP, DPhP and BBP were easily degraded, but DEHP was difficult to degrade; under anaerobic conditions, DBP, DPhP and BBP were easily degraded, but DEP and DEHP were difficult to degrade. Aerobic degradation rates were up to 10 times faster than anaerobic degradation rates.     

Comparison of different valent iron on anaerobic sludge digestion: Focusing on oxidation reduction potential,dissolved organic nitrogen and microbial community

• ORP value from −278.71 to −379.80 mV showed indiscernible effects on methane yield. • Fe(II) and Fe(III) promoted more degradation of proteins and amino acids than Fe⁰. • The highest enrichment of Geobacter was noted in samples added with Fe⁰. • Cysteine was accumulated during iron enhanced anaerobic sludge digestion. • Both iron content and valence were important for methane production. This study compared effects of three different valent iron (Fe⁰, Fe(II) and Fe(III)) on enhanced anaerobic sludge digestion, focusing on the changes of oxidation reduction potential (ORP), dissolved organic nitrogen (DON), and microbial community. Under the same iron dose in range of 0−160 mg/L after an incubation period of 30 days (d), the maximum methane production rate of sludge samples dosed with respective Fe⁰, Fe(II) and Fe(III) at the same concentration showed indiscernible differences at each iron dose, regardless of the different iron valence. Moreover, their behavior in changes of ORP, DON and microbial community was different: (1) the addition of Fe⁰ made the ORP of sludge more negative, and the addition of Fe(II) and Fe(III) made the ORP of sludge less negative. However, whether being more or less negative, the changes of ORP may show unobservable effects on methane yield when it ranged from −278.71 to −379.80 mV; (2) the degradation of dissolved organic nitrogen, particularly proteins, was less efficient in sludge samples dosed with Fe⁰ compared with those dosed with Fe(II) and Fe(III) after an incubation period of 30 d. At the same dose of 160 mg/L iron, more cysteine was noted in sludge samples dosed with Fe(II) (30.74 mg/L) and Fe(III) (27.92 mg/L) compared with that dosed with Fe⁰ (21.75 mg/L); (3) Fe⁰ particularly promoted the enrichment of Geobacter, and it was 6 times higher than those in sludge samples dosed with Fe(II) and Fe(III) at the same dose of 160 mg/L iron.     

Mercury removal from flue gas using nitrate as an electron acceptor in a membrane biofilm reactor

Membrane bioreactor achieved mercury removal using nitrate as an electron acceptor. The biological mercury oxidation increased with the increase of oxygen concentration. Ferrous sulfide could make both Hg²⁺ and MeHg transform into HgS-like substances. Nitrate drives mercury oxidation through katE, katG, nar, nir, nor, and nos. Mercury (Hg⁰) is a hazardous air pollutant for its toxicity, and bioaccumulation. This study reported that membrane biofilm reactor achieved mercury removal from flue gas using nitrate as the electron acceptor. Hg⁰ removal efficiency was up to 88.7% in 280 days of operation. Oxygen content in flue gas affected mercury redox reactions, mercury biooxidation and microbial methylation. The biological mercury oxidation increased with the increase of oxygen concentration (2%‒17%), methylation of mercury reduced with the increase of oxygen concentration. The dominant bacteria at oxygen concentration of 2%, 6%, 17%, 21% were Halomonas, Anaerobacillus, Halomonas and Pseudomonas, respectively. The addition of ferrous sulfide could immobilize Hg²⁺ effectively, and make both Hg²⁺ and MeHg transform into HgS-like substances, which could achieve the inhibition effect of methylation, and promote conversion of mercury. The dominant bacteria changed from Halomonas to Planctopirus after FeS addition. Nitrate drives mercury oxidation through katE, katG, nar, nir, nor, and nos for Hg⁰ removal in flue gas.