Regulatory off-gas analysis from the evaporation of Hanford simulated waste spiked with organic compounds

After strontium/transuranics removal by precipitation followed by cesium/technetium removal by ion exchange, the remaining low-activity waste in the Hanford River Protection Project Waste Treatment Plant is to be concentrated by evaporation before being mixed with glass formers and vitrified. To provide a technical basis to permit the waste treatment facility, a relatively organic-rich Hanford Tank 241-AN-107 waste simulant was spiked with 14 target volatile, semi-volatile, and pesticide compounds and evaporated under vacuum in a bench-scale natural circulation evaporator fitted with an industrial stack off-gas sampler at the Savannah River National Laboratory. An evaporator material balance for the target organics was calculated by combining liquid stream mass and analytical data with off-gas emissions estimates obtained using U.S. Environmental Protection Agency (EPA) SW-846 Methods. Volatile and light semi-volatile organic compounds (<220 degrees C BP, >1 mm Hg vapor pressure) in the waste simulant were found to largely exit through the condenser vent, while heavier semi-volatiles and pesticides generally remain in the evaporator concentrate. An OLI Environmental Simulation Program (licensed by OLI Systems, Inc.) evaporator model successfully predicted operating conditions and the experimental distribution of the fed target organics exiting in the concentrate, condensate, and off-gas streams, with the exception of a few semi-volatile and pesticide compounds. Comparison with Henry's Law predictions suggests the OLI Environmental Simulation Program model is constrained by available literature data.     

Solar light induced and TiO2 assisted degradation of textile dye reactive blue 4

Aqueous solutions of reactive blue 4 textile dye are totally mineralised when irradiated with TiO2 photocatalyst. A solution containing 4 x 10(-4) M dye was completely degraded in 24 h irradiation time. The intensity of the solar light was measured using Lux meter. The results showed that the dye molecules were completely degraded to CO2, SO4(2-), NO3-, NH4+ and H2O under solar irradiation. The addition of hydrogen peroxide and potassium persulphate influenced the photodegradation efficiency. The rapidity of photodegradation of dye intermediates were observed in the presence of hydrogen peroxide than in its absence. The auxiliary chemicals such as sodium carbonate and sodium chloride substantially affected the photodegradation efficiency. High performance liquid chromatography and chemical oxygen demand were used to study the mineralisation and degradation of the dye respectively. It is concluded that solar light induced degradation of textile dye in wastewater is a viable technique for wastewater treatment.     

Excellent dye degradation performance of FeSiBP amorphous alloys by Fenton-like process

Amorphous alloys are being newly applied in wastewater treatment because of their unique atomic packing structure. They possess excellent degradation efficiency, stability and reusability. In this work, Fe₈₀Si₁₀B₁₀ and Fe₈₃Si₅B₈P₄ amorphous ribbons exhibited advanced catalytic performance for the degradation of Methyl Blue (MB) and Rhodamine B (RhB) dyes, and the color removal reach nearly 100% within 11 min for both the dyes. Compared with the Fe₈₀Si₁₀B₁₀ amorphous ribbon, the Fe₈₃Si₅B₈P₄ ribbon showed higher degradation efficiency due to its lower reaction activation energy, higher electron transfer ability and higher Fe content, and the formation of the galvanic cell between the strong Fe–P bonds and the weak Fe–B bonds. It also exhibited high stability and reusability. The degradation efficiency was improved when the appropriate concentration of H₂O₂ is added. As regards the pH, high degradation efficiency was observed in acidic MB solution, but it decreased as the pH increased up to pH 7. The application of the electro–Fenton–like process is discussed, which can effectively improve the degradation performance in a nearly natural solution. This study presents a high efficiency low-cost catalyst for synthetic dye degradation and expands the functional applications of Fe-based amorphous alloys.     

Prevention of progressive collapse for building structures to member disappearance by accidental actions

Recently some building structures have collapsed because of losses of vertical load carrying capacities resulting from accidental events. In this paper, limit analysis called Compact Procedure is applied to some cases of collapsed structures and the key-elements in the structures are identified using Sensitivity Analysis. Two collapse prevention methods are discussed. For truss structures, the collapse can be prevented by reinforcement of members having sensitivity greater than 0.3–0.4. For frame structures, the relations between the sensitivity and the progressive collapse are defined using a safety factor and the progressive collapse can be prevented by fixing X braces into each span of the top floor.     

Variability of nitrous oxide and carbon dioxide emissions continuously measured in solid waste incinerators

Nitrous oxide and carbon dioxide were continuously measured and variability of emission factors (EFs) was evaluated in five municipal waste incinerators (MWIs) and four industrial waste incinerators (IWIs) from 24 to 86 days between 2008 and 2011. N₂O EFs were calculated by Monte Carlo simulation and mean N₂O EFs were 7.1, 107, 127, 219 g N₂O/ton waste combusted in MWIs with selective catalytic reduction (SCR) for NOx control, MWIs with selective non-catalytic reduction (SNCR), IWIs with SNCR, and a MWI using fluidized bed with SNCR, respectively. Climate-relevant CO₂ EFs ranged from 0.45 to 0.72 ton CO₂/ton waste combusted in MWIs. Maximum values of upper limit for 95% confidence intervals (CIs) of N₂O EFs estimated in each MWIs with SCR, MWIs with SNCR, IWIs with SNCR were 185, 94, 101% of mean N₂O EFs, respectively. Meanwhile, maximum values of upper limit for 95% CIs of CO₂ EFs were much lower as between 18 and 36% in those facilities. 84% CIs of mean N₂O EFs in MWIs with SNCR and IWIs with SNCR were overlapped indicating those values are not significantly different.     

Case study in Korea of manufacturing SRF for polyurethanes recycling in e-wastes

Statistics showed that approximately 1,195,000 refrigerator units (116,094 metric tons) were recycled annually in Korea’s formal sector. Although the recycling level for these was satisfactory, collecting and processing polyurethane at recycling centers (RCs) posed several problems, including the risk of fire from the incinerator, the generation of fugitive dust, and the high cost of disposal. The objective of our study is to provide an overview of refrigerator recycling and to introduce polyurethane solid refuse fuel (SRF) manufacturing facilities. These facilities, installed at four regional RCs in Korea, have a capacity of 800 kg/h, a motor of 476 kWh, and cost $664,300 (USD) to construct (criteria two facilities). According to our examination of the physico-chemical properties of SRF product, all results in categories have been satisfied with the quality standards. In terms of finances, RCs can reduce the total disposal cost from $160–175 to $60 by installing facilities, which results in savings of (on average) $180,546 annually. The Metropolitan Electronics Recycling Center, for example, has reduced its costs by $180,880 each year. Their return on investment was calculated to be about 3 years and 8 months (assuming no operating expenses) or 7 years and 4 months (including operating expenses).     

Development of combined plant of biogas and bio solid-refuse-fuel from swine manure slurry

Journal of Material Cycles and Waste Management - An environment-friendly treatment of organic waste like swine manure and food waste is considered to be big challenge, because the residue of...     

Decomposition of greenhouse gases by plasma

The topic of decomposition and reduction of greenhouse gases is becoming an important issue in tackling the global warming effect since several years ago. Several technologies, including plasma-utilized process, were proposed to improve the treatment ability for the destruction of green house gases usually emitted by industrial activities. In this review paper, the application of plasma to reduce the emission of greenhouse gases was briefly summarized.