Evaluating source separation of plastic waste using conjoint analysis

Using conjoint analysis, we estimated the willingness to pay (WTP) of households for source separation of plastic waste and the improvement of related environmental impacts, the residents' loss of life expectancy (LLE), the landfill capacity, and the CO(2) emissions. Unreliable respondents were identified and removed from the sample based on their answers to follow-up questions. It was found that the utility associated with reducing LLE and with the landfill capacity were both well expressed by logarithmic functions, but that residents were indifferent to the level of CO(2) emissions even though they approved of CO(2) reduction. In addition, residents derived utility from the act of separating plastic waste, irrespective of its environmental impacts; that is, they were willing to practice the separation of plastic waste at home in anticipation of its "invisible effects", such as the improvement of citizens' attitudes toward solid waste issues.     

Intracellular localization of vanadium in the fan worm Pseudopotamilla occelata

A very high level of vanadium was found to be contained in the polychaete worm Pseudopotamilla occelata collected in 1992–1993 from the Sanriku coast on the main island of Japan. The vanadium concentration (mean±SD=5500±1800 g g^-1 dry wt) in the worm's branchial crown which is composed of many bipinnate radioles was approximately 100 times higher than that (mean±SD=60±25 g g^-1 dry wt) in the trunk body. Electron probe X-ray microanalysis revealed that a large amount of vanadium was present in the outer potion of the epidermis of the bipinnate radiole. Analytical electron microscopy for a cryo-section of the bipinnate radioles indicated that vanadium was localized in electron-dense deposits in the apical portion of epidermal cells. From an examination of the fine structures, the locality of the electron-dense deposits were found to correspond to that of the apical vacuoles in the epidermal cells. It was concluded that most of the vanadium in P. occelata was contained in the vacuoles of the epidermal cells of the bipinnate radioles.     

Ozonation as an efficient pretreatment method to alleviate reverse osmosis membrane fouling caused by complexes of humic acid and calcium ion

Humic acids (HA) didn’t cause obvious reverse osmosis (RO) membrane fouling in 45 h. Osmotic pressure (NaCl) affected slightly the RO membrane fouling behavior of HA. Ca²⁺ promoted aggregation of HA molecules and thus aggravated RO membrane fouling. Ozonation eliminated the effect of Ca²⁺ on the RO membrane fouling behavior of HA. The change of the structure of HA was related to its membrane fouling behavior. Humic acid has been considered as one of the most significant sources in feed water causing organic fouling of reverse osmosis (RO) membranes, but the relationship between the fouling behavior of humic acid and the change of its molecular structure has not been well developed yet. In this study, the RO membrane fouling behavior of humic acid was studied systematically with ozonation as a pretreatment method to control RO membrane fouling. Furthermore, the effect of ozone on the structure of humic acid was also explored to reveal the mechanisms. Humic acid alone (10–90 mg/L, in deionized water) was found not to cause obvious RO membrane fouling in 45-h operation. However, the presence of Ca²⁺ aggravated significantly the RO membrane fouling caused by humic acid, with significant flux reduction and denser fouling layer on RO membrane, as it was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). However, after the pretreatment by ozone, the influence of Ca²⁺ was almost eliminated. Further analysis revealed that the addition of Ca²⁺ increased the particle size of humic acid solution significantly, while ozonation reduced the SUVA₂₅₄, particle size and molecular weight of the complexes of humic acid and Ca²⁺ (HA-Ca²⁺ complexes). According to these results and literature, the bridge effect of Ca²⁺ aggregating humic acid molecules and the cleavage effect of ozone breaking HA-Ca²⁺ complexes were summarized. The change of the structure of humic acid under the effect of Ca²⁺ and ozone is closely related to the change of its membrane fouling behavior.     

The top-down mechanism for body-mass-abundance scaling

Scaling relationships between mean body masses and abundances of species in multitrophic communities continue to be a subject of intense research and debate. The top-down mechanism explored in this paper explains the frequently observed inverse linear relationship between body mass and abundance (i.e., constant biomass) in terms of a balancing of resource biomasses by behaviorally and evolutionarily adapting foragers, and the evolutionary response of resources to this foraging pressure. The mechanism is tested using an allometric, multitrophic community model with a complex food web structure. It is a statistical model describing the evolutionary and population dynamics of tens to hundreds of species in a uniform way. Particularities of the model are the detailed representation of the evolution and interaction of trophic traits to reproduce topological food web patterns, prey switching behavior modeled after experimental observations, and the evolutionary adaptation of attack rates. Model structure and design are discussed. For model states comparable to natural communities, we find that (1) the body-mass abundance scaling does not depend on the allometric scaling exponent of physiological rates in the form expected from the energetic equivalence rule or other bottom-up theories; (2) the scaling exponent of abundance as a function of body mass is approximately -1, independent of the allometric exponent for physiological rates assumed; (3) removal of top-down control destroys this pattern, and energetic equivalence is recovered. We conclude that the top-down mechanism is active in the model, and that it is a viable alternative to bottom-up mechanisms for controlling body-mass-abundance relations in natural communities.     

Environmental occurrence of nitrotriphenylene observed in airborne particulate matter

1- and 2-Nitrotriphenylenes were found in the airborne particulate matter extracts collected in central Tokyo between the winter of 1998 and the winter of 1999. In particular, we have identified and quantified nitrotriphenylenes in the airborne particulate matter extracts collected over four consecutive 6-h periods on 2 December 1999. The concentrations of 1- and 2-nitrotriphenylene ranged from 0.04 to 0.44 and from 0.02 to 0.47 ng/m3, respectively, and the concentrations in the airborne particulate matter extracts collected during the 18:00-24:00 h time period were the highest of the four collection periods. 1-Nitropyrene and 2-nitrofluoranthene were also identified and quantified in the four 6-h samples. Although the concentrations of 1- and 2-nitrotriphenylenes were not higher than that of 2-nitrofluoranthene except during the 18:00-24:00 h time period, the concentrations were much higher than that of 1-nitropyrene during the four collection periods.The higher concentrations of 1- and 2-nitrotriphenylenes during the 18:00-24:00 h time period are presumably responsible for the high reactivity of parent triphenylene with NO2/NO3/N2O5, and high stability of 1- and 2-nitrotriphenylenes toward O3 + O2. In addition, the observed isomer distribution of nitrotriphenylenes suggested that direct emission of nitrotriphenylenes is also a source as well as their atmospheric formation.     

Detection and average content levels of carcinogenic and mutagenic compounds from the particulates on diesel and gasoline engine mufflers

Carcinogenic and mutagenic compounds, which were extracted from the particulates that adhered to inner surfaces of diesel and gasoline engine mufflers, were quantified by the series method of Soxhlet extraction, liquid-liquid partition, thin-layer chromatography, and spectrofluorometry. Mutagenic activity of their neutral and acidic fractions was tested in the improved Ames assay by the preincubation method with Salmonella typhimurium TA98 in the presence and absence of metabolic activation system (S-9 mix). The average content levels (μg/g tar) of polycyclic aromatic hydrocarbons from gasoline engine cars were greater than those from diesel engine vehicles. However, the levels of nitro derivatives of PAHs and polycyclic quinones from the diesel engines were greater than from the gasoline engines. Mutagenic activity of the diesel acidic fraction was the highest among the diesel and gasoline fractions, and was significantly higher in the absence of the S-9 mix. Furthermore, the relative value (R_{c = 0}) of infrared absorption of carbonyl stretching vibration to that of methylene asymmetric stretching vibration of the diesel acidic fraction was the highest among the diesel and gasoline fractions. These results strongly suggest that highly direct-acting mutagens in the acidic fraction are at higher levels in diesel emission particulates than those from gasoline, and that these mutagens are carboxylic acid, aldehyde, and alcohol derivatives of PAHs and NPAHs.     

Leaching of phosphorus from incinerated sewage sludge ash by means of acid extraction followed by adsorption on orange waste gel

Ashes from sewage sludge incineration have a high phosphorus content, approximately 8% (W/W), which indicates a potential resource of the limiting nutrient. Incineration of sewage sludge with subsequent recovery of phosphorus is a relatively new sludge treatment technique. In this article, the leaching of phosphorus by using sulfuric acid as well as hydrochloric acid by means of several batch experiments was presented. At the same time a selective recovery of phosphorus by adsorption was also discussed. The e ects of acid concentration, temperature and time on extraction were studied. The phosphorus leaching increased with the increase in acid concentration and temperature. Kinetic studies showed that the complete leaching of phosphorus took place in less than 4 h. Selective adsorption of phosphorus by using orange waste gel provided a hint for recovery of this natural resource, which eventually could meet the ever-increasing requirement for phosphorus. The overall results indicated that the incinerated sewage sludge ash can be treated with acid to e ciently recover phosphorus and thus can be considered a potentially renewable source of phosphorus.     

Characterization of the e ective cellulose degrading strain CTL-6

An e cient cellulose degrading bacteria exists in the thermophilic wheat straw-degrading community, WDC2. However, this strain cannot be isolated and cultured using conventional separation techniques under strict anaerobic conditions. We successfully isolated a strain of e ective cellulose degrading bacteria CTL-6 using a wash, heat shock, and solid-liquid alternating process. Analysis of its properties revealed that, although the community containing the strain CTL-6 grew under aerobic conditions, the purified strain CTL-6 only grew under anaerobic culture conditions. The strain CTL-6 had a striking capability of degrading cellulose (80.9% weight loss after 9 days of culture). The highest e ciency value of the endocellulase (CMCase activity) was 0.404 mol/(min mL), cellulose degradation e ciency by CTL-6 was remarkably high at 50–65°C with the highest degradation e ciency observed at 60°C. The 16S rRNA gene sequence analysis indicated that the closest relative to strain CTL-6 belonged to the genus Clostridium thermocellum. Strain CTL-6 was capable of utilizing cellulose, cellobiose, and glucose. Strain CTL-6 also grew with Sorbitol as the sole carbon source, whereas C. thermocellum is unable to do so.     

Factors affecting waste generation: a study in a waste management program in Dhaka City, Bangladesh

Information on waste generation, socioeconomic characteristics, and willingness of the households to separate waste was obtained from interviews with 402 respondents in Dhaka city. Ordinary least square regression was used to determine the dominant factors that might influence the waste generation of the households. The results showed that the waste generation of the households in Dhaka city was significantly affected by household size, income, concern about the environment, and willingness to separate the waste. These factors are necessary to effectively improve waste management, growth and performance, as well as to reduce the environmental degradation of the household waste.