Cell Immobilized FOG-Trap System for Fat, Oil, and Grease Removal from Restaurant Wastewater

Cell immobilized lipase-producing bacteria on three different matrices were incorporated in a fat-, oil-, and grease (FOG) trap system for restaurant wastewater treatment. During a 16-day laboratory-scale experiment for the treatment of synthetic FOG wastewater containing soybean oil, no significant difference (two-tailed t test at 95% confidence interval) in the FOG removal between two systems was observed at FOG influent ≤ 1,000?mg/L. However, the typical trap showed lower FOG removal efficiency than the matrix-based system when the influent FOG concentration was increased to ≥ 5,000?mg/L. In addition, the matrix-based trap system was able to sustain a stable high FOG removal, with <100?mg/L effluent, even at 10,000 mg/L influent FOG. Based on FOG heights measured and mass balance calculations, 97.4 and 99.5% of the total FOG load for 16 days were removed in a typical trap and matrix-based system, respectively. About 93.6% of the removal in the matrix-based was accounted to biodegradation. The 30-day full-scale operations demonstrated a distinguishably better performance in the matrix-based system (92.7±9.06% of 1,044.8±537.27?mg FOG/L) than in the typical trap system (74.6±27.13% of 463.4±296.87?mg FOG/L) for the treatment of barbeque restaurant wastewater. Similarly, matrix-based system revealed higher chemical oxygen demand removal (85.9±11.99%) than the typical trap system (60.4±31.26%). Characterizations of the influent, emulsified, adsorbed and effluent FOG indicated that straight saturated fatty acids constituted the cause of clogging problems in the FOG-trap and piping system.     

Co2e emissions abatement costs of reducing natural gas flaring in Brazil by investing in offshore GTL plants producing premium diesel

This study evaluates the possibility of installing an offshore gas-to-liquids (GTL) plant in Brazil to reduce Natural Gas (NG) flaring, curb carbon dioxide equivalent (CO₂e) emissions and produce premium diesel. CO₂e emissions abatement costs were estimated by comparing two alternatives. The first alternative (baseline) considers that the volume of NG flared will not be reduced. Low-sulfur fuels (diesel and naphtha) will be obtained by investing in treatment units in Brazilian refineries. These are hydrotreating units for unstable compounds and hydrodesulfurizer units for fluid catalytic cracking (FCC) naphtha. Currently in Brazilian refineries, without any investment, the lower-quality streams that should be removed from diesel and gasoline pools to comply with higher specifications are light-cycle oil and FCC naphtha, respectively. The second alternative considers an offshore microchannel GTL plant producing synthetic crude oil, or syncrude. The upgrading of this syncrude is done by a mild-hydrocracking unit. This alternative allows the production of low-sulfur diesel, reducing gas flaring and co-producing high-quality naphtha. The results show that CO₂e emissions abatement costs of offshore GTL in Brazil should range between negative US$ 2.00 and positive 80.00/tCO₂e. Nevertheless, the typical scenario shows an average figure of US$ 37.00/tCO₂e abated.     

Can China benefit from adopting a binding emissions target?

In the run-up to the Copenhagen climate summit, the USA announced an emissions reduction target of 17% by 2020 (relative to 2005), and the EU of 20–30% (relative to 1990). For the same time horizon, China offered to reduce the CO₂-intensity of its economy by 40–45% (relative to 2005), but rejects a legally binding commitment. We use the targets announced by the EU and the USA to analyze the potential gain for China if it were to adopt a binding emissions target and join an international emissions trading scheme. We show that China would likely benefit from choosing a binding target well below its projected baseline emissions for 2020.     

Seasonal Operation of Ponds for Chemical Precipitation of Wastewater

Wastewater precipitation ponds (fellingsdams) are conventional stabilization ponds adapted to cold climate by the use of chemical precipitation to attain sufficient removal efficiency of impurities, primarily phosphorus. The objective with this investigation was to study the influence of an interruption of the dosage of coagulant during summer periods at two fellingsdam systems (Orrviken and Lockne) in the middle of Sweden. The investigation took place over two years characterized by unusual precipitation conditions; 2001 was intense in precipitation whereas summer 2002 represented a dry season. The results showed that there is a potential to utilize the summer biological activity in fellingsdams. At Orrviken the effluent quality measured as organic matter and phosphorus in the effluent was just slightly above the values that were reached by chemical precipitation. At Lockne the performance was lower. The organic matter reduction at Orrviken in the summers of 2001 and 2002 were 71 and 67%, respectively, compared to previous years using precipitant when the average was 78%. At Lockne, however, the values in the summers of 2001 and 2002 were 36 and 18%, respectively, compared to previous years using precipitant when the average was 55%. The phosphorous reduction at Orrviken in the summers of 2001 and 2002 were 85 and 89%, respectively, compared to previous years using precipitant when the average was 95%; at the Lockne plant, the phosphorous reduction during the summers of 2001 and 2002 were 60 and 66%, respectively, compared to the previous years' average of 86%. The nitrogen reduction varied considerably over the two summer periods. The reduction at Orrviken was 13% in 2001 and 58% in 2002; the reduction at Lockne was 13% in 2001 and 33% in 2002. Reference values of nitrogen reduction during normal operations were not available.     

Effect of Metallic Iron Concentration on End-Product Distribution during Metallic Iron-Assisted Autotrophic Denitrification

The main objective of this study was to determine the optimum composition of a reactive porous medium containing sand and metallic iron, to be used for Fe(0)-assisted hydrogenotrophic denitrification. This determination is important to ensure that the end-product distribution after such treatment is acceptable, i.e., ammonia formation due to abiotic nitrate reduction by metallic iron in such media is minimized, while a reasonable rate of biological denitrification is maintained. Based on a previous study it was established that steel wool, with its relatively low specific surface area, exhibited the least propensity to abiotically reduce nitrate. It was also established that to achieve acceptable end-product distribution, the steel wool concentration in the reactive porous media has to be lowered even below the lowest value, i.e., 4.0?g steel wool/m3 of sand, used during that study. It was further hypothesized that to counter any detrimental effect of lower steel wool concentration on biological nitrate removal rate, increase of the retention time in porous media to values higher than 13 days, the maximum value investigated in that study, may be necessary. In the present study, experiments were conducted in batch reactors containing denitrifying microorganisms and various concentrations of steel wool and in semibatch reactors containing sand seeded with denitrifying microorganisms and various concentrations of steel wool. Based on the results of the semibatch experiments, it appears that to achieve acceptable end-product distribution, the steel wool concentration in the reactive porous media has to be maintained around 2.0?g steel wool/m3 sand and the corresponding retention time in the reactive media must be around 26 days.     

Modeling of Airborne Debris around Overplow Deflectors during High-Speed Snowplowing

An engineering model is presented to calculate the trajectory of airborne debris that adversely affects visibility during high-speed snow plowing. Reynolds-averaged Navier-Stokes equations are solved numerically with turbulence-modeling, particle-tracking, and cutting-edge approximations. Results suggest snow can be divided into splash and snow cloud when engineering treatments to improve visibility for snowplow drivers and following traffic. Calculated results confirm the findings of windtunnel and road tests, specifically that the trap angle of overplow deflectors should be less than 50° to eliminate snow debris blowing over the top of the plow onto the windscreen.     

Simultaneous Removal of Carbon and Nitrogen from Swine Wastewater Using an Immobilized-Cell Reactor

A single-stage phosphorylated polyvinyl alcohol immobilized-cell reactor with three operation modes was employed to investigate the efficiency of simultaneous carbon/nitrogen removal from raw swine wastewater. In continuous aeration mode, the removal efficiency of chemical oxygen demand (COD) and total nitrogen (T-N) exceeded 70 and 8%, respectively, at hydraulic retention time of 10?days. In intermittent aeration (IA) mode, the removal efficiency of COD and T-N was more than 85 and 46%, respectively, when the reactor was set at 50% aeration duration to cycle time to operate at three aerobic-anoxic cycles per day. When oxidation-reduction-potential control was adopted to control the duration of the anoxic period in the real-time controlled (RTC) IA mode for a 4?h aeration period, the total cycle time was reduced by about 20% with a slight increase in removal efficiency of COD (87%) and T-N (47%). The system with no extra chambers required is efficient in simultaneous carbon/nitrogen removal.     

美国文化遗产保护领域中的税费激励政策

文章介绍了美国文化遗产保护领域中税费激励制度的形成、发展与政策影响力,借此引发我国采用税费制度促进城市文化遗产保护的建议。