Individual and Synergistic Effects of Metronidazole,Amoxicillin, and Ciprofloxacin on Methane Fermentation with Sewage Sludge

Methane fermentation is widely used to dispose of sewage sludge at wastewater treatment plants (WWTPs), due to production of renewable energy in the form of biogas. Antibiotics present in wastewater may accumulate in a sewage sludge. The aim of the present study is to investigate the impact of three antibiotics from different classes in three different doses on methane production from sewage sludge. For this purpose, metronidazole (MET), amoxicillin (AMO), and ciprofloxacin (CIP) are individually added to anaerobic reactors with sewage sludge collected from municipal WWTP. The antibiotics’ highest concentration (1024 mg kg^?1 of AMO; 512 mg kg^?1 of MET and CIP) lowers methane production and methane content in biogas. MET exerts the most marked effect and lowers methane production to 36.8 ± 3.7 mL CH₄ kg^?1 volatile solids. Tested antibiotics probably inhibit methanogenic archaea, which results in volatile fatty acids (VFAs) accumulation. Addition of MET results in accumulation of many kinds of VFAs with the highest concentration of acetic acid (17.52 ± 1.85 g L^?1). The addition of of AMO results in accumulation of butyric acid only (253.00 ± 15.89 g L^?1). However, addition of CIP results in accumulation of mainly acetic acid (7.58 ± 0.82 g L^?1) and isovaleric acid (2.01 ± 0.41 g L^?1). Next, synergistic effect of these antibiotics in a low concentration of 16 mg kg^?1 of AMO, 8 mg kg^?1 of MET, and 2 mg kg^?1 of CIP is measured in semi‐continuous conditions and causes inbibition of methane production and accumulation of VFAs.     

疏浚淤泥化学絮凝−真空预压深度脱水效果评价

为实现疏浚淤泥高效快速脱水减容,选取化学絮凝和真空预压相结合的脱水技术,利用自制真空预压抽滤装置对5种类型絮凝剂调理淤泥进行系列室内脱水试验,通过上清液高度、泥水分界面高度、沉降速率、底泥含水率等指标,综合评价疏浚淤泥沉降过程与深度脱水效果。结果表明：5种絮凝剂对应最优添加量分别为Ca(OH)2(1 500 mg/L)、PAFSI(200 mg/L)、PAC(200 mg/L)、HCA(50 mg/L)、APAM(500 mg/L);与原始淤泥自然沉降过程相比（底泥高度17.14 cm、含水率96.8%）,真空预压可实现絮凝调理淤泥脱水减容、底泥平均含水率降至53.5%,使底泥体积进一步压缩20.48%～36.99%;真空预压作用下,絮凝调理淤泥在50 min内达到沉降速率峰值,前120 min内淤泥絮凝效果明显、泥水分离程度占据主导;与原始淤泥真空预压对比,絮凝?真空预压大幅提升淤泥沉降速率、有效缩短峰值对应沉降时间,最优絮凝剂（APAM）底泥沉降速率峰值、淤泥总高度沉降速率峰值对应时间点缩短87.5%和83.33%,峰值速率分别增加3.56倍、5.18倍;添加适量絮凝剂能有效改善淤泥脱水性能,增大泥粒尺寸、防堵促排,加速疏浚淤泥沉降与泥水分离效率。化学絮凝?真空抽滤技术有利于实现疏浚淤泥减量化,显著缩短工期、加快施工进度、减少堆积占地,具有显著的工程应用价值。     

黄河三角洲外来入侵物种米草对底泥微生物群落的影响

对黄河三角洲2个米草分布区及2个非米草分布区底泥中微生物生物量进行了测定,结果显示:大米草(S. anglica)分布区底泥中细菌、放线菌、真菌、反硝化细菌、硫酸盐还原细菌总数显著多于非米草分布区,米草的分布促进了底泥中微生物量的增加;互花米草(S. alterniflora)分布区的细菌、真菌总数多于大米草分布区,而其它微生物量则少于大米草分布区.     

Geotechnical properties of municipal sewage sludge

The geotechnical properties of municipal sewage sludge, in particular those pertinent to the handling and landfilling of the material, are presented. Index, drying, compaction, shear strength and consolidation tests were conducted on the material at different states of biodegradation. The organic content and specific gravity of solids were found to be inversely related, with typical organic contents of 50–70% and specific gravity of solids values of 1.55–1.80. The density of the compacted material was low in comparison with mineral soils. Standard Proctor compaction yielded a maximum dry density of 0.56 tonne/m³ at 85% water content. Laboratory vane-shear and triaxial compression tests indicated that, below about 180% water content, the shear strength of the sludge material increased exponentially with reducing water content. Consolidated-undrained triaxial compression tests on the pasteurised sludge material indicated an effective angle of shearing resistance of 32° for the moderately degraded material and 37° for the strongly degraded material. Biogas was produced at rates of up to 0.33 L/day/kg slurry due to ongoing biodegradation and the resulting pore pressure response must be taken into account in any stress analysis. Consolidation tests using the hydraulic consolidation cell, oedometer and triaxial apparatus indicated that the sludge material was highly compressible although practically impermeable, for example the coefficient of permeability for the moderately degraded slurry was of the order of 10⁻⁹m/s. However, creep deformation was significant with typical coefficient of secondary compression values of 0.02–0.08 for the compacted material. A more free-draining material was produced at higher states of biodegradation.     

The effect of the new Massachusetts Bay sewage outfall on the concentrations of metals and bacterial spores in nearby bottom and suspended sediments

Since the new outfall for Boston's treated sewage effluent began operation on September 6, 2000, no change has been observed in concentrations of silver or Clostridium perfringens spores (an ecologically benign tracer of sewage), in bottom sediments at a site 2.5 km west of the outfall. In suspended sediment samples collected with a time-series sediment trap located 1.3 km south of the outfall, silver and C. perfringens spores increased by 38% and 103%, respectively, in post-outfall samples while chromium, copper, and zinc showed no change. All metal concentrations in sediments are <50% of warning levels established by the Massachusetts Water Resources Authority. An 11-year data set of bottom sediment characteristics collected three times per year prior to outfall startup provides perspective for the interpretation of post-outfall data. A greater than twofold increase in concentrations of sewage tracers (silver and C. perfringens) was observed in muddy sediments following the exceptional storm of December 11-16, 1992 that presumably moved contaminated inshore sediment offshore.     

SBR、PAC-SBR反应器处理制药废水污泥变化特征

探讨了SBR和PAC-SBR反应器处理盐酸林可霉素原料液生产废水过程中活性污泥特征的变化.随着废水投加量的增加,PAC-SBR反应器的污泥性能始终优于SBR反应器,但是由于盐酸林可霉素原料液生产废水对生物有较强的抑制作用,PAC-SBR反应器和SBR反应器中污泥的活性均发生恶化,COD去除率已明显下降,单独采用SBR或PAC-SBR法处理已难以达到排放标准,必须进行工艺的组合.PAC-SBR反应器较SBR反应器在污泥性质及处理效率上均有一定的改善,对处理盐酸林可霉素原料药生产废水有一定的优势.     

Bacterial mitigation of pollutants in acid drainage using decomposable plant material and sludge

 Effects of a clay-lime spiked sewage sludge and fresh decomposable ryegrass on the mitigation of an acid drainage were studied in the laboratory. Treatments (dry ameliorant weight/leachate ratio) were: (1) sludge (air-dried) at rates of 0, 8, 16 and 24%, (2) ryegrass at 0, 1, 1.5 and 2% (dry weight), (3) sludge (at the above-mentioned rates) and 1.5% ryegrass mixture. Measurements of mitigation (according to the criteria of changes in pH, Fe, S, Al and heavy metals) made every 10th day for 100 days showed ryegrass/sludge combination the most effective while sustaining mitigation longest, with or without the influence of sulphate-reducing bacteria (SRB). Sulphate and Fe in the acid drainage decreased in the order: sludge+ryegrass>sludge>ryegrass by 180, 40, 19; and 96, 83 and 54% respectively, compared with controls. An 11-fold decrease in soluble Al was caused by the highest rate of the combined sludge-ryegrass treatment but Al was doubled by the sludge-only treatment, and only minimally affected (2% reduction) by the ryegrass-only treatment. For the sludge plus ryegrass treatments at the highest rate of application, pH levels increased significantly, from 2.3 to >7 units and within 20 days of SRB activation, the concentration of Co, Cu, Mn, Ni and Zn decreased 3-, 15-, 90-, 3- and 50-fold respectively. Received: 30 March 1999 · Accepted: 31 January 2000     

第四纪地层钻具起下钻受阻和岔孔事故处理

在厚第四纪地层中进行勘探施工,最常见且最难以处理的孔内事故钻具下钻受阻,导致经常出现岔孔等孔内事故,对钻探施工影响很大。本文运用现代钻探理论,结合现场事故处理经验等资料,分析论证了在钻进和停钻时地层、泥浆和钻具等因素对钻孔孔径的影响,并对此问题的处理了探讨。