Performance evaluation of a biotrickling filter treating a mixture of oxygenated VOCs during intermittent loading

Laboratory scale-studies on the biodegradation of a 1:1:1 weight mixture of three oxygenated volatile organic compounds (VOCs), ethanol, ethyl acetate, and methyl-ethyl ketone (MEK) in a biotrickling filter (BTF) were carried out using two identically sized columns, filled with different polypropylene rings. The performance of the BTFs was examined for a period of 10 months applying several operational strategies. Similar performance was obtained for both supports. Intermittent flow rate of trickling liquid was shown beneficial to improve the removal efficiency (RE). Continuous feeding of VOC resulted in an excessive accumulation of biomass so high pressure drop was developed in less than 20-30 d of operation. Intermittent VOC loading with night and weekend feed cut-off periods passing dry air, but without addition of water, was shown as a successful operational mode to control the thickness of the biofilm. In this case, operation at high inlet loads (ILs) was extended for more than 75 d maintaining high REs and low pressure drops. Outlet emission concentrations lower than 100 mg Cm(-3) were obtained for ILs up to 100 g Cm(-3)h(-1) working at 15s of empty bed residence time. The most easily biodegradable compounds ethanol and ethyl acetate were used primarily than MEK. After a 3-wk-starvation period, the system performance was almost restored since the first d of operation, being the removal of the less biodegradable compound, MEK, partially deteriorated.     

Congener-specific analysis of non-dioxin-like polychlorinated biphenyls in blood collected from 195 pregnant women in Sapporo City, Japan

We conducted a congener-specific analysis of non-dioxin-like polychlorinated biphenyls (non-dioxin-like PCBs) in blood collected between July 2002 and July 2004 from 195 pregnant women living in Sapporo City of Hokkaido Prefecture, Japan. The present study is one of the few studies in which full congener concentrations of non-dioxin-like PCBs have been measured in the blood of pregnant women. Of the 195 pregnant women, 101 were primipara (mean: 28.8 years, median: 28.0 years) and 94 were multipara (mean: 32.3 years, median: 33.0 years). Among the 197 non-dioxin-like PCB congeners, 58 congeners were identified in the blood of pregnant women. The arithmetic mean total concentrations of 58 non-dioxin-like PCB congeners in the blood of primiparous and multiparous mothers in Sapporo City were 42.2-329.3 (mean: 114.5, median: 98.6) and 31.5-258.0 (mean: 100.3, median: 91.4)ngg(-1)lipid, respectively. The results show that the contamination of non-dioxin-like PCBs in the blood of women has decreased compared to past levels in other domestic areas, in which the subject age was similar to that in this study. The results of the present study indicate that current levels of non-dioxin-like PCBs in the blood of Japanese women and can be used as baseline data for future temporal trends. The sums of the ratios of the concentrations of hexaCBs and heptaCBs to the total concentrations of 58 non-dioxin-like PCB congeners in the blood of primiparous and multiparous mothers were 78.5% and 77.7%, respectively. The hexaCBs ratios in the blood of primiparous and multiparous mothers were 45.4% and 44.7%, respectively. HexaCB-153 among hexaCBs congeners, the most abundant congener in the blood of primiparous and multiparous mothers, contributed approximately 22.0% and 21.8% to the total concentrations of 58 non-dioxin-like PCBs congeners that were measured in the blood, respectively. Among the non-dioxin-like PCB congeners measured in the present study, hexaCB-138, heptaCB-170, heptaCB-180, and heptaCB-182/heptaCB-187 also showed high ratios to total concentrations of 58 non-dioxin-like PCB congeners detected in the blood of primiparous and multiparous mothers. With regard to the relationship between the total concentrations of 58 non-dioxin-like PCB congeners in maternal blood and the number of deliveries or the age of primiparous and multifarious mothers, the total levels of these PCB congeners tended to decreases with increases in the number of deliveries and significantly increased with increasing maternal age in both groups. Furthermore, significant correlations were observed between the total concentrations of these PCB congeners in blood and the age of primiparae and multiparae. The concentrations of hexaCB-153 in the blood of primiparous and multiparous mothers showed a close correlation to the total concentrations of these PCBs, suggesting that hexaCB-153 could be an indicator of total concentrations of non-dioxin-like PCB congeners in the blood of pregnant women.     

Natural attenuation of a plume from an emplaced coal tar creosote source over 14 years

An emplaced source of coal tar creosote within the sandy Borden research aquifer has documented the long-term (5140 days) natural attenuation for this complex mixture. Plumes of dissolved chemicals were produced by the essentially horizontal groundwater flowing at about 9 cm/day. Eleven chemicals have been extensively sampled seven times using a monitoring network of approximately 280, 14-point multilevel samplers. A model of source dissolution using Raoult's Law adequately predicted the dissolution of 9 of 11 compounds. Mass transformation has limited the extent of the plumes as groundwater has flowed more than 500 m, yet the plumes are no longer than 50 m. Phenol and xylenes have been removed and naphthalene has attenuated from its maximum extent on day 1357. Some compound plumes have reached an apparent steady state and the plumes of other compounds (dibenzofuran and phenanthrene) are expected to continue to expand due to an increasing mass flux and limited degradation potential. Biotransformation is the major process controlling natural attenuation at the site. The greatest organic mass lost is associated with the high solubility compounds. However, the majority of the mass loss for most compounds has occurred in the source zone. Oxygen is the main electron acceptor, yet the amount of organics lost cannot be accounted for by aerobic mineralization or partial mineralization alone. The complex evolution of these plumes has been well documented but understanding the controlling biotransformation processes is still elusive. This study has shown that anticipating bioattenuation patterns should only be considered at the broadest scale. Generally, the greatest mass loss is associated with those compounds that have a high solubility and low partitioning coefficients.     

Municipal incineration bottom ash treatment using hydrothermal solidification

Solidification of municipal incineration bottom ash (MIBA) has been carried out using a hydrothermal processing method, in which the MIBA was first compacted in a mold at 5-20 MPa, and then hydrothermally cured in an autoclave under saturated steam pressure at 150-250 degrees C for 10-72 h. Experimental results showed that the tensile strength of the solidified body was greatly influenced by the addition of NaOH solution and fresh cement in the MIBA. The hydrothermal curing temperature and time exerted a significant influence on the development of tensile strength of solidified body. The strength development is speculated to be due primarily to the formation of 1.1 nm tobermorite. Laboratory leaching tests were conducted to determine the amount of heavy metals dissolved from the solidified bodies and the results showed that under the hydrothermal conditions of this study the leaching of heavy metals was very low. As such, the hydrothermal processing method may have a high potential for recycling MIBA.     

Modification of soil humic matter after 4 years of compost application

Two soil plots, 1 ha each, were amended yearly for 4 years, respectively, with 35.8 and 71.6 Mg ha(-1) yr(-1) of mature compost (CM) obtained from food and vegetable residues. The compost, amended soils, and a control soil plot after 4 years (S4), were analyzed for humin (HUC), humic acid (HAC), fulvic acid (FAC), and non-humic carbon (NHC) content. Compared to S4, the amended soil contained more humified C (HAC, FAC and HUC) and less NHC. Further evidence of the effect of compost on soil organic matter was obtained by the analysis of the humic acid (HA) fractions isolated from both the compost and the soils. These were characterized by elemental analyses and Diffuse Reflectance Infrared Fourier Transformed spectroscopy. The HAs isolated from CM and from S4 were significantly different. The HAs isolated from the amended plots were more similar to HA isolated from CM than to HA isolated from S4. The experimental data of this work indicate that the compost application may affect significantly the soil organic matter composition, and that the approach used in this work allows one to trace the fate of compost organic matter in soil.     

Preparation and characterization of ceramic products by thermal treatment of sewage sludge ashes mixed with different additives

The study of the ceramic characteristics of sludge ashes, alone or mixed with additives (kaolin, montmorillonite, illitic clay, powdered flat glass) includes characterization of additives, preparation of probes (dry or wet mixed), thermal treatment (up to 1200 degrees C, except melting or deformation) and control (densities, compressive strengths and water absorption). Thermal treatment increases the density and compressive strength of probes (both parameters go through maxima, with later decreases) and decreases the absorption of water. The densification is also revealed by the evolution of the ratio of decrease of volume/loss of mass. The maximum values of compressive strengths were obtained for 25% of illitic clay, montmorillonite and glass powder. Densification concerning probes with sludge ashes alone does not occur with kaolin. Experimental data were adjusted to exponential relationships between compressive strengths and densities for every composition, and also to a general equation for all probes. The apparent density obtained was adjusted to a non-linear dependence with temperature, leading to a maximum in density and permitting calculating the temperature of occurrence of this maximum. The adjustment was not possible for probes containing kaolin, requiring presumably higher temperatures to densify. Water absorption has low values for ashes or kaolin probes, intermediate values for illite and powdered flat glass probes and high values for montmorillonite probes. Excepting with kaolin, ceramic materials with better characteristics than sludge ashes without additives were obtained at lower treatment temperatures.     

Effect of irrigation on the survival of total coliforms in three semiarid soils after amendment with sewage sludge

Sewage sludges are increasingly used in soil amendment programmes, although not without risk since they contain, among other potential hazards, high concentrations of total coliform bacteria. In this paper we have studied the effect of irrigation on the survival of total coliforms in three semiarid degraded soils with different agricultural practices. Fresh sewage sludge was added at 50 g kg(-1) soil, and incubated in both the presence and absence of irrigation. The absence of irrigation led to a sharp decrease in the number of total coliforms in all soils, with the bacteria disappearing in 40 days. Irrigation produced a substantial initial increase in the number of coliforms in the three soils, although after 80 days there was none growing in any of the soils. The results showed that there were significant differences in the survival of coliform bacteria due to the presence or absence of irrigation.     

Recovery of PET from packaging plastics mixtures by wet shaking table

Recycling requires the separation of materials appearing in a mass of wastes of heterogeneous composition and characteristics, into single, almost pure, component/material flows. The separation of materials (e.g., some types of plastics) with similar physical properties (e.g., specific gravity) is often accomplished by human sorting. This is the case of the separation of packaging plastics in municipal solid wastes (MSW). The low cost of virgin plastics and low value of recycled plastics necessitate the utilization of low cost techniques and processes in the recycling of packaging plastics. An experimental study was conducted to evaluate the feasibility of production of a PET product, cleaned from PVC and PS, using a wet shaking table. The wet shaking table is an environmentally friendly process, widely used to separate minerals, which has low capital and operational costs. Some operational variables of the equipment, as well as different feed characteristics, were considered. The results show that the separation of these plastics is feasible although, similarly to the mineral field, in somewhat complex flow sheets.     

Adsorption of Acid Red 73 on copper dithiocarbamate precipitate-type solid wastes

Three solid wastes, copper N,N'-bis(dithiocarboxy)piperazine ([CuBDP](n)), copper diethyldithiocarbamate (Cu(DDTC)(2)) and copper dimethyldithiocarbamate (Cu(DMTC)(2)), were prepared and tested as adsorbents to remove Acid Red 73 from wastewater. It was found that the three precipitates all could effectively adsorb the dye but their adsorption abilities were rather different. The maximum adsorption amounts of the coordination polymer precipitate [CuBDP](n) reached as high as 364mg g(-1), much greater than those of Cu(DDTC)(2) and Cu(DMTC)(2) (42.9 and 37.8mg g(-1), respectively). The investigation of adsorption models showed these adsorption processes followed the pseudo-second-order kinetic equation and the adsorption balances could be described with both Langmuir and Freundlich isotherms, but the latter seemed to be more suitable. Their adsorption nature was inferred to be physical adsorption and mainly depended on the hydrophobic interaction between these precipitates and Acid Red 73. This is the first example for the reutilization of metal dithiocarbamate precipitates as solid wastes to date.     

Identification of particles containing chromium and lead in road dust and soakaway sediment by electron probe microanalyser

Individual particles containing Cr and/or Pb and other major components were identified in road dust from a heavily used road (hereinafter 'heavy traffic road dust'), road dust from a residential area and soakaway sediment by electron probe microanalyser to locate their sources and carrier particles. Individual particles containing high levels of Cr and/or Pb (>or=0.2%) were identified using wavelength dispersive spectrometry (WDS) map analysis. Chromium, Pb and other major elements were then determined by means of a combination of WDS and energy-dispersive spectrometry in all identified particles, 50 particles containing neither Cr nor Pb from each type of road dust and soakaway sediment, and yellow road line markings. WDS map analysis revealed that many particles containing both Cr and Pb were present among the identified particles in heavy traffic road dust, whereas they were minor components in road dust from the residential area and soakaway sediment. The plots of X-ray intensities of Cr vs. Pb were linear for the identified particles containing both Cr and Pb in heavy traffic road dust, and the line closely fitted the plots for the three yellow road line marking samples. Individual particles were then classified using cluster analysis of element components. The results revealed that the adsorption of source materials or released metals onto soil minerals occurred in road dust and soakaway sediment, that the yellow road line markings were sources of Cr and Pb in heavy traffic road dust, and that materials containing Fe as a major component, such as stainless steel, were additional sources of Cr in both road dust and soakaway sediment.