Fine Removal Research Articles

Separation of fine organic particles by a low-pressure hydrocyclone (LPH)

The separation performance of a low-pressure hydrocyclone was tested using fine organic particles from 1 to 700μm. The dimensions of the low-pressure hydrocyclone were an inflow diameter of 30mm, a cylinder length of 575mm, an overflow diameter of 60mm, an underflow diameter of 50mm, a cylinder diameter of 335mm and a cone angle of 68°. The low-pressure hydrocyclone was operated with a lower inlet pressure (average 1.38–5.56kPa) that could be maintained under water level differences that ranged from 17.5 to 53.5cm between the water surface of the feeding mass cylinder and the middle of the inlet pipe of the low-pressure hydrocyclone. By varying the inflow rate, underflow ratio and feed concentration, the separation performance of the low-pressure hydrocyclone was affected. The separation performances were determined from total separation efficiency and grade efficiency. Separation performances were determined according to the different inflow rates of 400, 600, 800 and 1000mls−1 and their respective underflow ratios that ranged from 5% to 30%. The maximum total separation efficiencies for each inflow rate were 41%, 46% and 46% at 400, 800 and 1000mls−1 inflow rates, respectively, and at underflow rates of 30% of the inflow rates. In addition, a total separation efficiency of 46% was employed at 600mls−1 of inflow rate and with an underflow rate of 25% its inflow rate. As the feed concentration increased from 25 to 150mgl−1, the separation performances were gradually decreased. For the fine particles ranging 1–200μm, the grade efficiency was higher at the higher inflow rate (higher than 600mls−1) and higher underflow rate. However, for the coarse particles ranging 400–700μm, the grade efficiency was higher at the lower inflow rate (lower than 600mls−1) and higher underflow rate. The cut-point (d50) values ranged from 30 to 200μm for a feed size range of 1–700μm. The Response Surface Method (RSM) model predicted an optimum operating inflow rate and underflow ratio of 721mls−1 of inflow rate and 30%, respectively, for the low-pressure hydrocyclone at a maximum total separation efficiency. Based on these findings, further design and operating adaptation of low-pressure hydrocyclones used for fine solids removal in recirculating aquaculture systems is expected.

Experimental Study of Treating Petroleum Refinery Wastewater by Vacuum Distillation

Vacuum distillation (VD) by NaOH was used for treatment of petroleum refinery wastewater, and the optimal experimental conditions including operation vacuum degree, initial pH, feeding process were also investigated. Chemical oxygen demand (COD), conductivity and pH value were utilized to estimate the removal efficiency for treatment of refinery wastewater. Based on experimental results, it can be concluded that NaOH displays higher efficiency for the treatment of refinery wastewater, the pellucid effluents with satisfied COD removal efficiency (99%) and low salinity were obtained in fully batch process at operation vacuum degree of-0.085 MPa, operation time of 50 min, initial pH of 11, and the corresponding pH values of effluents varied from 7 to 9. Thus, in view of fine COD and mineralization removal efficiency, the VD technology is an effective approach to treat petroleum refinery wastewater.

Water Model on Fine Inclusion Removal by Bubble Flotation in RH Refining Process

With the development of socio-economic and science and technology, People are more strict to the requirement of steel quality. A physical model was established according to the “similarity theory” to simulate the real 180t RH-TB vacuum refining device. Liquid steel is simulated by Nacl solution, Fine inclusions is simulated by high density polypropylene less than 0.04mm in diameter. The influence regularity of treatment time, lift gas flow rate and method of addition, the amount and time of NaHCO3 addition on the inclusions removal rate have been discussed, the optimal values for each influence factor have been found and can be used in optimizing the refining technology.

Upgrading of a wastewater treatment plant with a hybrid moving bed biofilm reactor (MBBR)

The wastewater treatment plant of Porto Tolle (RO, Italy) was originally projected for 2200 person equivalent (p.e.) and it was made of a pumping station, an activated sludge oxidation tank (395 m 3 ), a settler (315 m 3 ), and two sludge drying beds. Other units were not yet in use in 2008: a fine screen, a sand and grit removal unit, a new settler (570 m 3 ), a disinfection tank and a sludge thickener. Effective hydraulic load was 245% higher, organic load was 46% lower and nitrogen load was 39% higher than project values. Moreover, higher pollutant loads and more strict emission limits for nitrogen were expected. So the plant was upgraded: the old settler was divided into a sector of 180 m 3 that was converted into a predenitrification tank, and a sector of 100 m 3 that was converted into a hybrid MBBR tank filled with 50% AnoxKaldnes TM K3 carriers; the new settler was connected to the hybrid MBBR, and the other units were started. Biofilm growth was observed two months after plant restarting, its concentration reached 1.1 g TS /m 2 (0.26 kg TS /m 3 ), while activated sludge concentration was 2.0-2.8 kg TSS /m 3 in all the period of study. The upgraded plant treats 1587 m 3 /d wastewater with 57 kg COD /d, 23 kg BOD /d and 13.3 kg N /d, and has a significant residual capacity; the effluent respects all emission limits.

Intensive rearing of cod larvae (Gadus morhua) in recirculating aquaculture systems (RAS) implementing a membrane bioreactor (MBR) for enhanced colloidal particle and fine suspended solids removal

Intensive rearing of Atlantic cod larvae (Gadus morhua) was investigated in a conventional recirculating aquaculture system (cRAS) and a membrane modified RAS (mRAS). Cod larvae are sensitive to water quality, and beneficial effects on growth and survival from enhanced removal of colloidal particles, fine suspended solids and nutrient reduction were expected. Membrane bioreactors (MBR) are a potential technology for advanced water treatment in aquaculture. The aim of this project was to assess the effect of an MBR system for enhanced treatment in RAS. A cRAS and mRAS treatment train were operated in parallel. In the mRAS Scheme 8.5% of the recycle stream was filtered through the membrane at any time. The mRAS scheme demonstrated a significantly lower turbidity and number of colloidal particles as compared to the cRAS scheme, as well as significantly lower bacteria concentrations and more stability. Overall a 13% higher cod larvae growth (weight, %) at 40dph and 3.5% higher survival rate at 50dph was measured in the mRAS scheme. Results show there is a great potential of implementing a membrane filtration system in aquaculture recycling systems.

LED 광질이 관엽식물의 기능성 최적화에 미치는 영향

White light and compound light were found to be the ideal light sources for improving the functionality and ornamental value of indoor plants and reducing the cost of maintenance, but because compound light hinders people from recognizing the original color of plants and makes their eyes easily tired, white light was considered the optimal light satisfying all of the ornamental value, economic efficiency and functionality resulting from plant growth. On the other hand, in the results of examining physiological changes before and after treatment on fine dust PM10 and carbon dioxide removal capacity in a closed chamber under an artificial light source, the patterns of carbon dioxide and fine dust removal were similar among the treatment groups according to light condition, but according to plant type, the removal rate per unit leaf area was highest in Spathiphyllum and lowest in Dieffenbachia. In the experiment on dust and carbon dioxide removal, the photosynthetic rate was over 2 times higher after the treatment, and the rate increased particularly markedly under compound light and white light, suggesting that the photosynthetic rate of plants increases differently according to light quality. These results show that light quality has a significant effect on the photosynthetic rate of plants, and suggests that plants with a high photosynthetic rate also have a high carbon dioxide and dust removal capacity. In conclusion, the photosynthetic rate of foliage plants increased under white and blue light that affect photosynthesis and the increased photosynthetic rate reduced carbon dioxide and fine dust, and therefore white and compound light were found to be the optimal light sources most functional and economically efficient in improving ornamental value and indoor air quality.

Filter material treatment methods for fine dust removal and consistent regeneration

Methods are analyzed for “finishing” treatment of filter cloths imparting special material properties. An abundance of thermal, chemical, mechanical, and special treatments for filter cloth and combination of these treatments makes it possible to create materials for efficient application under specific operating conditions.

Ni–Al layered double hydroxides as catalyst precursors for CO2 removal by methanation

The effect of nickel content on the structure and activity of co-precipitated Ni–Al layered double hydroxides (LDHs) as catalyst precursors for CO2 removal by methanation was studied by variation of the Ni2+/Al3+ molar ratio (Ni2+/Al3+ = 3.0, 1.5 and 0.5), and of the reduction and reaction temperatures as well as of the space velocities. Powder X-ray diffraction (PXRD), H2 chemisorption, and temperature programmed reduction (TPR) techniques were applied for physicochemical characterization of the samples. It was specified that the nano-scaled dimensions of the as-synthesized samples also generate nano-metrical metallic nickel particles (PXRD). The existence of readily and hardly reducible Ni2+–O species in the studied samples (TPR), affects catalytic performance. The studied catalysts hydrogenate CO2 effectively to residual concentrations of the latter in the range of 0–10 ppm at reaction temperatures from 400 to 220 °C and space velocities between 22,000 and 3000 h−1. The variation of the CO2 methanation activity with the changes of space velocities depends on the nickel content, and reduction and reaction temperatures. After reduction at 400 and 450 °C, a sample of Ni2+/Al3+ = 3.0 has demonstrated the highest conversion degree at all the reaction temperatures and space velocities, while a catalyst of Ni2+/Al3+ = 0.5 dominated in the methanation activity after reduction within 530–600 °C. The Ni2+/Al3+ = 1.5 catalyst data take intermediate position between Ni2+/Al3+ = 3.0 and Ni2+/Al3+ = 0.5 often closer to Ni2+/Al3+ = 3.0 ones. The studied Ni–Al LDH systems are found to be promising catalyst precursors for fine CO2 removal from hydrogen-rich gas streams through the methanation reaction, depending on the technological regime of catalyst activation.

Investigation on the Novel Technology of the Fine Inclusion Removal due to the Dispersed <i>In Situ</i> Phase Induced by the Composite Ball Explosive Reaction

The production of high purity steel is a major task for the iron and steel enterprises in the 21st century. To improve the quality of steel products and produce the cleanness steel, the key technique is to control inclusions in the molten steel. In the present investigation, a novel fine inclusion removal technology due to the dispersed in-situ phase induced by the composite ball explosion reaction was put forward. A composite ball with this function has been designed and the industrial experimental investigation was also carried out. The results indicate that feeding composite ball in RH ladle is a novel technology and the inclusion in the molten steel can be removed effectively. Compared with conventional inclusion removal technology, the number of the oxide inclusion can be decreased to a lower level and the inclusion size becomes much finer. Using this novel technology, the total oxygen in the as-cast slab can approach to 6ppm. This novel technology can be achieved without special facility and be realized in most steelmaking plant.

Investigation on Cleansing the if Molten Steel with the Dispersed <i>In Situ</i> Phase Induced by the Composite Ball Explosive Reaction in RH Ladles

A novel fine inclusion removal technology due to the dispersed in-situ phase induced by the composite ball explosive reaction was put forward. A composite ball with this function has been designed and prepared using a laboratory model batch type balling disc (at 12 rpm) and the composite ball has been fed at the end of RH refining. The results indicate that feeding composite ball in RH ladle is a novel technology and the inclusion in the IF molten steel can be removed effectively. Compared with conventional inclusion removal technology, the number of the oxide inclusion can be decreased to a lower level and the inclusion size becomes finer. Using this novel technology, the total oxygen in the as-cast slab can approach to 5ppm and the steel production cost for per ton can be reduced by 5 ~12 RMB.

Novel Concept of Cleansing the Liquid Steel by the Fine <i>In-Situ</i> Phase due to the Composite Ball Explosion Reaction in RH Ladle

The production of high purity steel is a major task for the iron and steel enterprises in the 21st century. To improve the quality of steel products and produce the cleanness steel, the key technique is to control inclusions in the molten steel. In the present investigation, a novel fine inclusion removal technology due to the dispersed in-situ phase induced by the composite ball explosion reaction was put forward. A composite ball with this function has been designed and the industrial experimental investigation was also carried out. The results indicate that feeding composite ball in RH ladle is a novel technology and the inclusion in the molten steel can be removed effectively. Compared with conventional inclusion removal technology, the number of the oxide inclusion can be decreased to a lower level and the inclusion size becomes much finer. Using this novel technology, the total oxygen in the as-cast slab can approach to 6ppm. This novel technology can be achieved without special facility and be realized in most steelmaking plant.

Cleaning IF molten steel with dispersed in-situ heterophases induced by the composite sphere explosive reaction in RH ladles

A novel fine inclusion removal technology was put forward with dispersed in-situ heterophases induced by the composite sphere explosive reaction. A composite sphere with this function was designed and prepared using a laboratory scale batch-type balling disc (at 12 r/min), and the composite sphere was fed at the end of the RH refining process. The results indicate that inclusions in the IF molten steel can be removed effectively by feeding composite spheres in RH ladle. Compared with conventional inclusion removal technology, using this novel technology, the amount of oxide inclusions can be decreased to a lower level and the inclusion size becomes finer, the total oxygen content in the as-cast slab can approach 5×10−6, and the cost per ton of steel produced can be reduced by 5–12 Yuan RMB.

Piranha attacks in dammed streams used for human recreation in the State of São Paulo, Brazil

In recent years, attacks by piranhas have become a common problem in dammed portions of rivers and streams in the State of Sao Paulo, Southeastern Brazil. In two outbreaks recorded in two neighboring counties in the Northwest region of the state, 74 bathers were bitten. Only one bite per person was recorded during a short period of the year. The bites were related to parental care and/or defense of spawning territory, which confirms previous studies and demystify the attacks by these legendary fish, as they are perceived by most people. Placement of fine mesh nets and removal of aquatic vegetation stopped the attacks.

Performance Evaluation of a Cotton Heaping Machine

A cotton loading/unloading machine for heaping operation was developed and evaluated for its capacity and fibre parameters. A centrifugal fan with open impeller was modified as Rembert fan by attaching a conical disc over the fan impeller. The major components of the machine were inlet flexible pipe, casing, impeller, perforated conical disc, electric motor, outlet GI pipe and trolley. Three conical discs of different perforation sizes were tested to optimize the output and efficiency of the developed machine. A conical disc with 3 mm perforation size was found as optimum size, without choking, for attachment at the inlet side of impeller. The capacity of the developed machine for heaping was 2400 kg cotton/h. The average fine trash content removal efficiency was 20.8 percent. No measurable fibre damage was observed during conveying of cotton.

Long‐term fine caliber hair removal with an electro‐optic Q‐switched Nd:YAG Laser

In spite of major advances in hair removal therapy, fine caliber hair remains a significant challenge for laser- and light-based devices. Evaluate a novel Electro-Optic (EO) Q-switched Nd:YAG laser for pigmented fine caliber hair removal in the Standard Single and a double pulse (DP) mode. Eleven patients underwent four laser treatments at monthly intervals. Bilateral anatomical regions received to one side the standard single pulse (SSP) while the other side the DP option. Blinded investigators conducted hair counts at 6 months post-treatment and after 24 months. Patients assessed hair loss and discomfort. Six patients rated their satisfaction at 6 months. At 6 months, investigators found a reduction of 50% in hair counts with the DP and 46% with standard pulse. Ninety percent in DP and 50% in SSP reported none to mild discomfort. Transient erythema and edema was observed with a lower severity rating with the DP. There were no other untoward effects. 83.3% of patients who completed the study at 6 months expressed satisfaction with the results. At 24 months hair loss was maintained at the same rate. The EO Q-switched Nd:YAG laser is an effective option for the permanent treatment of unwanted fine hair and has a high-patient satisfaction rate. There is less therapeutic discomfort in the DP mode.

Performance of a Novel Rotating Gas-Liquid Separator

A novel gas separation process makes use of a rotating phase separator to separate micron-sized droplets from a gas stream. Based on an industrial scale design, a water/air separator is constructed and tested. The first experiment concerns the drainage of large fractions of separated liquid. During operation, drainage is observed via windows and a descriptive model is formulated. Because of the major influence on overall separation efficiency, liquid drainage is a key issue in the separator design. The second experiment comprises a droplet collection efficiency measurement using micron-sized droplets dispersed within the airstream. The separation efficiency of fine droplet removal is measured. This is an important factor in reducing capital costs.

El Chichón volcano, April 4, 1982: volcanic cloud history and fine ash fallout

This retrospective study focuses on the fine silicate particles (<62 µm in diameter) produced in a large eruption that was otherwise well studied. Fine particles represent a potential hazard to aircraft, because as simple particles they have very low terminal velocities and could potentially stay aloft for weeks. New data were collected to describe the fine particle size distributions of distal fallout samples collected soon after eruption. Although, about half of the mass of silicate particles produced in this eruption of ~1 km3 dense rock equivalent magma were finer than 62 µm in diameter, and although these particles were in a stratospheric cloud after eruption, almost all of these fine particles fell to the ground near (<300 km) the volcano in a day or two. Particles falling out from 70 to 300 km from the volcano are mostly <62 µm in diameter. The most plausible explanation for rapid fallout is that the fine ash nucleates ice in the convective cloud and initiates a process of meteorological precipitation that efficiently removes fine silicates. These observations are similar to other eruptions and we conclude that ice formation in convective volcanic clouds is part of an effective fine ash removal process that affects all or most volcanic clouds. The existence of pyroclastic flows and surges in the El Chichon eruption increased the overall proportion of fine silicates, probably by milling larger glassy pyroclasts.

Removal rate and surface roughness in the lapping and polishing of RB-SiC optical components

Abstract Optical components made of reaction-bonded silicon carbide (RB-SiC) have aroused the interest of researchers and engineers due to their distinct properties, such as low density, high hardness and low thermal expansion coefficient. The present study focuses on efficient fabrication of RB-SiC optical components. Here, a two-stage fabrication process is proposed. Firstly, a plate fixed with solid pellet-shaped abrasives is used for rapid removal of surface error and initial smoothing. After that, fine error removal and surface polishing is performed using felt buffs and diamond abrasives. Material removal rates and surface roughness are measured based on a Form Talysurf surface profiler. The final surface roughness with an initial value of Ra = 110.8 nanometer (nm) reached 21.6 nm after 5 min of lapping by adjusting the size of abrasives continuously from 30 to 10 micrometer (μm), and then convergent to 10.7 nm after 15 min of polishing using different sized diamond pastes as the polishing abrasive. The validity of the two-stage process in terms of efficiency and surface quality has been verified by experiments. How these factors are affected by process parameters such as the relative rotation speed, abrasives grit size, etc. are also examined.

Numerical Study of the Effect of Ventilation Pattern on Coarse, Fine, and Very Fine Particulate Matter Removal in Partitioned Indoor Environment

An indoor size-dependent particulate matter (PM) transport approach is developed to investigate coarse PM (PM10), fine PM (PM2.5), and very fine PM (PM1) removal behaviors in a ventilated partitioned indoor environment. The approach adopts the Eulerian large eddy simulation of turbulent flow and the Lagrangian particle trajectory tracking to solve the continuous airflow phase and the discrete particle phase, respectively. Model verification, including sensitivity tests of grid resolution and particle numbers, is conducted by comparison with the full-size experiments conducted previously. Good agreement with the measured mass concentrations is found. Numerical scenario simulations of the effect of ventilation patterns on PM removal are performed by using three common ventilation patterns (piston displacement, mixing, and cross-flow displacement ventilation) with a measured indoor PM10 profile in the Taipei metropolis as the initial condition. The temporal variations of suspended PM10, PM2.5, and PM1 mass concentrations and particle removal mechanisms are discussed. The simulated results show that for all the of the three ventilation patterns, PM2.5 and PM1 are much more difficult to remove than PM10. From the purpose of health protection for indoor occupants, it is not enough to only use the PM10 level as the indoor PM index. Indoor PM2.5 and PM1 levels should be also considered. Cross-flow displacement ventilation is more effective to remove all PM10, PM2.5, and PM1 than the other ventilation patterns. Displacement ventilation would result in more escaped particles and less deposited particles than mixing ventilation.

Fine cleaning of dust from gaseous process media by granular filters with a connected layer structure

Advantages of granular filters with a connected layer structure over alternative means of ultrafine fine removal of mechanical impurities from gaseous process media are examined. Specific structural solutions for these vessels, and their operating parameters in the production of electronic devices, in biotechnology, during the production of electrolytic hydrogen, and in cryogenic engineering are presented. Methods are recommended for regeneration of multilayer filtering structures. Information on commercial and socioeconomic prospects of granular filters with a connected layer structure, which are employed for the fine removal of mechanical impurities from gaseous process media, are presented in the bibliography.