Source identification and characterization of the accumulating non-biodegradable organics in Korean reservoirs

An increase in the chemical oxygen demand (COD) has been noticed in most Korean reservoirs. Therefore, this research systematically investigated the causes of organic accumulation. Samples of soil affecting the quality of water of reservoirs were collected at various sources and analyzed for their organic characteristics. The COD to biochemical oxygen demand (BOD) ratio was used as the key parameter in the evaluation of non-biodegradable (NBD) organic accumulation in the reservoirs. Soil samples containing plant roots were agitated, with the supernatant showing COD/BOD ratios of less than 2.8, while those of the composted tree leaves were greater than 5.0, suggesting that humic substances produced in forest areas are a major cause of NBD organic accumulation in reservoirs. In addition, the organic fractionation of the leachate from leaching tests showed that of the various types of hydrophobic natural organic matter (NOM), the larger molecular weight humic acid makes a greater contribution than fulvic acid to the increase in the NBD COD in Korean reservoirs.     

Development of a highly sensitive extractive spectrophotometric method for the determination of nickel(II) from environmental matrices using N-ethyl-3-carbazolecarboxaldehyde-3-thiosemicarbazone

Nickel(II) reacts with N-ethyl-3-carbazolecarboxaldehyde-3-thiosemicarbazone (ECCT) and forms a yellow colored complex, which was extracted into n-butanol from sodium acetate and acetic acid buffer at pH 6.0. The absorbance value of the Ni(II)-ECCT complex was measured at different intervals of time at 400nm, to ascertain the time stability of the complex. The extraction of the complex into the solvent was instantaneous and stable for more than 72h. The system obeyed Beer's law in the concentration range of 1.2-5.6mugml(-1) of nickel(II), with an excellent linearity and a correlation coefficient of 0.999. The molar absorptivity and Sandell's sensitivity of the extracted species were found to be 1.114x10(4)Lmol(-1)cm(-1) and 5.29x10(-3)mugcm(-2) at 400nm, respectively. Hence, a detailed study of the extraction of nickel(II) with ECCT has been undertaken with a view to developing a rapid and sensitive extractive spectrophotometric method for the determination of nickel(II) when present alone or in the presence of diverse ions which are usually associated with nickel(II) in environmental matrices like soil and industrial effluents. Various standard alloy samples (CM 247 LC, IN 718, BCS 233, 266, 253 and 251) have been tested for the determination of nickel for the purpose of validation of the present method. The results of the proposed method are comparable with those from atomic absorption spectrometry and were found to be in good agreement.     

Attenuation of divalent toxic metal ions using natural sericitic pyrophyllite

The present study investigated the effectiveness of an inexpensive and ecofriendly alumino silicate clay mineral, sericitic pyrophyllite, as an adsorbent for the possible application in the removal of some divalent toxic metal cations such as Pb(2+), Cu(2+)and Zn(2+) from aqueous systems. Batch scale equilibrium adsorption studies were carried out for a wide range of initial concentration from 24.1 to 2410mumolL(-1) for lead, 78.65 to 7865mumolL(-1) for copper and 76.45 to 7645mumolL(-1) for zinc solutions. The removal of Pb(2+) was almost complete at low concentration (maximum lead removal capacity, LRC, 32mg of lead/g of pyrophyllite) with 10gL(-1) of adsorbent in a 30min equilibration time. The effects of temperature on adsorption of heavy metal ions were studied. The applicability of the Langmuir, Freundlich and Dubinin-Radushkevich adsorption models in each case of lead, copper and zinc adsorption was examined separately at different temperatures. The adsorption process was found to be endothermic and the Freundlich adsorption model was found to represent the data at different temperatures more suitably.     

Processing and Properties of Mixtures of PHB-V with Post-consumer LDPE

Mixtures of poly-β-(hydroxybutyrate-co-valerate) PHB-V with virgin and post-consumer low density polyethylene (LDPE) were prepared by melt mixing in proportions of 100/0, 90/10, 80/20, 70/30 and 0/100 (wt/wt%). The mixtures were analysed by infrared spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), melting flow index (MFI), tensile tests, scanning electron microscopy (SEM) and biodegradation in simulated soil. The DMTA and DSC curves of post-consumer LDPE suggested that this polymer was a mixture of LDPE and linear low density polyethylene (LLDPE). Virgin and post-consumer LDPE had lower MFI than PHB-V, but the blends showed higher index as the content of LDPE increased. The addition of LDPE reduced the tensile strength and Young’s modulus of the mixtures compared with PHB-V. SEM indicated poor interfacial adhesion between PHB-V and LDPE. PHB-V degraded slow and gradually, while both LDPE showed virtually no degradation under the conditions studied. The biodegradability of the blends depended on their composition and of the type of LDPE. LDPE improved the biodegradability of the mixtures.     

Influence of Technological Process on Biodegradation of PVA/Waxy Starch Blends in an Aerobic and Anaerobic Environment

Improving biodegradability of PVA/starch blends is a reality already documented by a number of works. Admittedly, mechanical properties of products (for example, tensile strength) are somewhat worse, but suitable composition optimizing or chemical modifying of starch may eliminate the problem to a large degree. This work is an attempt to find another potential effect influencing biodegradability, that of technological procedure for producing films from these blends on an extruder. The procedure with a so-called pre-extrusion step (two-stage) and dry-blend (single-stage) produced blends of slightest differences in achieved biodegradability (virtually within limits of experimental error) in aerobic (76 vs. 79%) as well as anaerobic breakdown (48 vs. 52%). Conversely, morphological analysis exhibited superior homogeneity of films prepared by the two-stage process; their tensile strength was also higher.     

Mechanical Property Characterization of Plasticized Sugar Beet Pulp and Poly(Lactic Acid) Green Composites Using Acoustic Emission and Confocal Microscopy

Sorbitol and glycerol were used to plasticize sugar beet pulp-poly(lactic acid) green composites. The plasticizer was incorporated into sugar beet pulp (SBP) at 0%, 10%, 20%, 30% and 40% w/w at low temperature and shear and then compounded with poly(lactic acid) (PLA) using twin-screw extrusion and injection molding. The SBP:PLA ratio was maintained at 30:70. As expected, tensile strength decreased by 25% and the elongation increased. Acoustic emission (AE) showed correlated debonding and fracture mechanisms for up to 20% w/w plasticizer and uncorrelated debonding and fracture for 30–40% sorbitol and 30% glycerol content in SBP–PLA composites. All samples had a well dispersed SBP phase with some aggregation in the PLA matrix. However, at 40% glycerol plasticized SBP–PLA composites exhibited unique AE behavior and confocal microscopy revealed the plasticized SBP and PLA formed a co-continuous two phase system.

Relationships between anaerobic consortia and removal efficiencies in an UASB reactor degrading 2,4 dichlorophenol (DCP)

To gain more insight into the interactions between anaerobic bacteria and reactor performances (chemical oxygen demand-COD, 2,4 dichlorophenol-2,4 DCP removals, volatile fatty acid-VFA, and methane gas productions) and how they depended on operational conditions the microbial variations in the anaerobic granular sludge from an upflow anaerobic sludge blanket (UASB) reactor treating 2,4 DCP was studied. The study was composed of two parts. In the first part, the numbers of methanogens and acedogens in the anaerobic granular sludge were counted at different COD removal efficiencies. The relationships between the numbers of methanogens, the methane gas production and VFA production were investigated. The COD removal efficiencies increased to 74% from 30% while the number of total acedogens decreased to 10 from 30 cfu ml(-1). The number of total methanogens and acedogens varied between 11 x 10(3) and 10 x 10(9)MPN g(-1) and 10 and 30 cfu ml(-1) as the 2,4 DCP removal efficiencies were obtained between 60% and 99%, respectively. It was seen that, as the number of total acedogens decreased, the COD removal efficiencies increased. However, the number of total methanogens increased as the COD removal efficiencies increased. Correlations between the bacterial number and with the removal efficiencies obtained in different operational conditions were investigated. From the results presented in this paper a high correlation between the number of bacteria, COD removals, methane gas percentage, 2,4 DCP removals and VFA was observed. In the second part, methanogen bacteria in the anaerobic granular sludge were identified. Microbial observations and biochemical tests were applied to identify the anaerobic microorganisms from the anaerobic granular sludge. In the reactor treating 2,4 DCP, Methanobacterium bryantii, Methanobacterium formicicum, Methanobrevibacter smithii, Methanococcus voltae, Methanosarcina mazei, Methanosarcina acetivorans, Methanogenium bourgense and Methanospirillum hungatei were identified.     

The greenhouse gas balance of the Province of Siena

There is a profound debate over how to assign greenhouse gas (GHG) responsibilities; therefore, we have decided to follow IPCC guidelines, as they offer the only standardized method. We have identified each type of greenhouse emission and its level of absorption. We have studied the province and its districts and municipalities. We have determined that the energy sector is that with the highest level of emissions, even if the per capita emissions of the Province of Siena are very low. This is caused by a very low level of industrialization and the presence of a local geothermal production of energy. In order to highlight this aspect, we have considered scenarios both with and without geothermal production. Our research was then focused on single districts (groups of homogenous municipalities) and municipalities, where we found great differences among the greenhouse emissions of the areas. We have constructed a map of the greenhouse emissions of the whole province. It has been interesting to note that there are 14 municipalities with net negative emissions, seven with low positive emissions, 12 with medium positive emissions and three with elevated positive emissions. These latter correspond to the main city and to two of the most industrialized municipalities.     

垃圾焚烧飞灰处置与资源化利用研究进展

随着生活垃圾焚烧处理方式的不断推广,焚烧飞灰的产生量也不断增加。按照我国固体废物分类方法,焚烧飞灰属于危险废物,必须进一步处置才能进入填埋场或资源化利用。本文分析了飞灰物理化学特性,论述了常规处置技术（水泥固化、化学药剂稳定化、酸溶剂提取和熔融固化等）存在的问题。将原始飞灰直接应用于水泥、混凝土或路基材料,飞灰中高含量的重金属和盐类会产生新的环境问题。飞灰水洗可以高效去除其中的可溶性盐类,水洗飞灰在焙烧后重金属的浸出浓度远低于原始飞灰烧结后的相应浓度,飞灰水洗-焙烧技术具有很好的应用前景。     

Kinetic extractions to assess mobilization of Zn, Pb, Cu, and Cd in a metal-contaminated soil: EDTA vs. citrate

Kinetic EDTA and citrate extractions were used to mimic metal mobilization in a soil contaminated by metallurgical fallout. Modeling of metal removal rates vs. time distinguished two metal pools: readily labile (QM1) and less labile (QM2). In citrate extractions, total extractability (QM1+QM2) of Zn and Cd was proportionally higher than for Pb and Cu. Proportions of Pb and Cu extracted with EDTA were three times higher than when using citrate. We observed similar QM1/QM2 ratios for Zn and Cu regardless of the extractant, suggesting comparable binding energies to soil constituents. However, for Pb and Cd, more heterogeneous binding energies were hypothesized to explain different kinetic extraction behaviors. Proportions of citrate-labile metals were found consistent with their short-term, in-situ mobility assessed in the studied soil, i.e., metal amount released in the soil solution or extracted by cultivated plants. Kinetic EDTA extractions were hypothesized to be more predictive for long-term metal migration with depth.