A pilot plant two-phase anaerobic digestion system for bioenergy recovery from swine wastes and garbage

A pilot plant bioenergy recovery system from swine waste and garbage was constructed. A series of experiments was performed using swine feces (SF); a mixture of swine feces and urine (MSFU); a mixture of swine feces, urine and garbage (MSFUG); garbage and a mixture of urine and garbage (AUG). The system performed well for treating the source materials at a high organic loading rate (OLR) and short hydraulic retention time (HRT). In particular, the biogas production for the MSFUG was the highest, accounting for approximately 865-930Lkg(-1)-VS added at the OLR of 5.0-5.3kg-VSm(-3)day(-1) and the HRT of 9 days. The removal of VS was 67-75%, and that of COD was 73-74%. Therefore, co-digestion is a promising method for the recovery of bioenergy from swine waste and garbage. Furthermore, the results obtained from this study provide fundamental information for scaling up a high-performance anaerobic system in the future.     

Nitrification/denitrification in an intermittent aeration process for swine wastewater

Abstract

Nitrogen removal by a methane fermentation plus activated sludge process with the intermittent aeration was presented based upon a full‐scale pig farm experiment. Swine wastewater had a T‐N/BOD ratio from 0.2–0.29. The BOD concentration input to the process ranged from 1050–1608 mg l^‐1 and the T‐N concentration from 273–350 mg l^‐1. More than 90% of organic carbon was removed in each experimental run. Only small concentrations of NO₃‐N were found in the effluent and higher than 60% of the T‐N and 73% of NH₄‐N which were loaded to the intermittent aeration tank was removed. The nitrogen balance of each run was calculated. Denitrification was estimated to be accountable for 45–90% of the T‐N removed in the intermittent aeration tank. Denitrification rate increased as the BOD concentration increased (> 1300 mg l^‐1). The T‐N removal percentage was a function of the T‐N/BOD ratio of the influent. Although higher DO concentration (> 3 mg l^‐1) did not enhance the denitrification rate, nitrification did maintain at relative higher rates at a lower DO concentration (ave. 1.5 mg l^‐1). An operational condition of intermittent interval of aeration/nonaeration at 1:1 hr is better than that of the condition at 3:1 hr. As a result, T‐N and NH4‐N were removed up to 30% and 40% respectively, and the denitrification rate reached 79% in the intermittent aeration tank. An experimental run in a pilot plant on treating anaerobically pretreated swine wastewater was observed to verify simultaneous nitrification/denitrification. The results of the full‐scale plant experimentation seem to be confirmed by those obtained from the pilot plant runs.     

Partitioning between soluble and insoluble fractions of major and trace elements in size-classified airborne particulate matter collected in Tokyo

Airborne particulate matter (APM) is a major air pollutant, and the effect on human health of fine APM (PM2.5) deposited deep inside the lungs has recently become a serious concern. Moreover, soluble constituents may leach from APM, and intensify some health disorders. To identify the soluble chemical constituents of APM, size-classified APM was sampled in central Tokyo, and the elemental compositions of the water-soluble, acid-soluble and insoluble fractions were investigated. The extraction procedure was validated by calculating the mass balance of soluble and insoluble fractions of a standard APM reference material (NIST SRM 1648). Among the major elements, Fe and Ti in APM of all size classes and K in coarse APM were distributed primarily in the insoluble fraction and were inferred to be present as oxides or silicates, whereas Na and Mg in all size classes and K in fine APM were primarily in the water-soluble fraction and were inferred to be have originated mainly from sea salt. Among the trace elements, Zn and Cd in the fine APM (d < 2 microm) had large enrichment factors, indicating an anthropogenic origin, and were distributed primarily in the water-soluble fraction. When fine anthropogenic APM enters into the lungs, leached toxic elements, such as Cd, may adversely affect health. The higher the bonding energy of the monoxide molecule of the element was, the higher its distribution ratio was in the water-soluble fraction. Therefore, many metallic elements in APM were inferred to be present as oxygen-bonded compounds.     

《淮河流域可持续发展战略研究》撷要

《淮河流域可持续发展战略研究》采取系统科学的方法，提出了较为完整的淮河流可持续发展战略体系，既是中国水利事业步入“大水利”举措的尝试，也弥补了从整体上研究中国大河流域可持续发展战略的不足，对于其他大河流域的可持续发展战略研究具有借鉴意义。     

Solid waste generated from ships: a case study on ship-waste composition and garbage delivery attitudes at Haiphong ports,Vietnam

Journal of Material Cycles and Waste Management - Ports and marine transportation play important roles in the development of Vietnam, but there are increasing concerns over environmental issues...     

Decomposing deflagration properties of acetylene under low temperatures

In this study, the decomposing deflagration properties of acetylene under temperatures down to −60 °C and pressures up to 0.2 MPa in a 1-L cylindrical closed vessel were experimentally investigated. The gases were ignited by an electric spark at the center of the vessel. The lower-limit pressures of decomposing deflagration by electric spark ignition were determined. The lower-limit pressure at 10 °C was 0.15 MPa, and it gradually increased with decreasing temperature. The lower-limit pressure at −60^oC was 0.18 MPa. The flame propagation properties, such as the pressure, were measured with pressure transducers mounted along the vessel. The maximum decomposing deflagration pressures and pressure rising rates also increased with decreasing temperature.     

Virus Particle Detection by Convolutional Neural Network in Transmission Electron Microscopy Images

A new computational method for the detection of virus particles in transmission electron microscopy (TEM) images is presented. Our approach is to use a convolutional neural network that transforms a TEM image to a probabilistic map that indicates where virus particles exist in the image. Our proposed approach automatically and simultaneously learns both discriminative features and classifier for virus particle detection by machine learning, in contrast to existing methods that are based on handcrafted features that yield many false positives and require several postprocessing steps. The detection performance of the proposed method was assessed against a dataset of TEM images containing feline calicivirus particles and compared with several existing detection methods, and the state-of-the-art performance of the developed method for detecting virus was demonstrated. Since our method is based on supervised learning that requires both the input images and their corresponding annotations, it is basically used for detection of already-known viruses. However, the method is highly flexible, and the convolutional networks can adapt themselves to any virus particles by learning automatically from an annotated dataset.     

Decomposing detonation and deflagration properties of ozone/oxygen mixtures

In this study, the decomposing detonation and deflagration properties of ozone/oxygen mixtures of up to 20 vol.% of ozone in oxygen under high pressure of up to 1.0 MPa in a tube were experimentally investigated. The mixtures were ignited by an electric spark at the end of the tube. Flame propagation properties such as flame velocity and pressure were measured with thermocouples and piezo electric transducers mounted along the tube. Slow and constant flame propagation profiles were obtained. We also investigated the quenching ability of a wire gauze as well as the concentration limit for flame propagation. However, in spite of slow flame propagation velocity and easy flame quenching properties under these experimental conditions, direct initiation of detonation by the driver detonation of the stoichiometric oxy-hydrogen mixture was easily achieved at much lower concentrations than the limit of deflagration. The observed detonation properties, such as wave velocity and pressure, agreed fairly well with C–J calculated values. The detonation velocity (900–1200 m/s) and the pressure ratio to initial pressures (5–9.5) were not affected by the initial pressure of the mixtures. Near the detonation limit, typical spinning detonations with oscillatory pressure waves were observed.     

Soil contamination by halogenated polycyclic aromatic hydrocarbons from open burning of e-waste in Agbogbloshie (Accra,Ghana)

Detailed composition of chlorinated and brominated polycyclic aromatic hydrocarbons (Cl-PAHs and Br-PAHs) generated during informal recycling of e-waste and their toxic relevance are still poorly understood. This study investigated the occurrence of Cl-PAHs and Br-PAHs in surface soil samples from the Agbogbloshie e-waste recycling site (Accra, Ghana) using quantitative gas chromatography–mass spectrometry (GC–MS) and comprehensive two-dimensional GC–time-of-flight mass spectrometry (GC × GC–ToFMS) profiling. The results of GC–MS analysis showed elevated concentrations in open e-waste burning areas (160–220 and 19–46 ng/g dry weight for Cl- and Br-PAHs, respectively) with substantial contribution from unidentified compounds (respectively, more than 36 and 70%, based on the total areas of potential peaks). Cl- and Br-PAHs from e-waste burning had a distinctive composition dominated by ring–ring compounds. Several homologue groups not monitored with GC–MS were found using GC × GC–ToFMS: PAHs with up to 5Cl or 3Br, mixed halogenated PAHs and chlorinated methylPAHs. The dioxin-like toxic equivalents of the identified Cl-/Br-PAHs in soils, estimated from their in vitro AhR agonist potencies relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin, were much lower than the range reported for chlorinated and brominated dioxins. However, the toxicity of the unidentified halogenated PAHs remained unclear.