Effects of Operating Parameters in Tubular Ultrafiltration

A parametric waste-specific study was conducted to develop a more mechanistic understanding of the tubular ultrafiltration system using a surrogate metalworking (MW) fluid as a model waste stream. An average gel layer concentration of 31% oil was calculated and the gel layer concentration was determined to be independent of transmembrane pressure and cross-flow velocity. The thin-film model adequately described limiting flux data collected in this study, due to the use of discrete cross-flow velocity∕MW fluid concentration experiments; thus, an improved mechanistic understanding was achieved. Mass transfer and thus the pressure-independent “limiting” permeate flux were generally comparable to values observed in a high-shear rotary UF system, for oil concentrations <26%. However, a decrease in net permeate flux was observed in the tubular ultrafiltration (UF) system at high feed oil concentrations; thus, a hybrid system (conventional tubular followed by high-shear rotary UF) is proposed for treatment applications where high concentrations are desired.     

Recovery and Marine Clay Stabilization of Heavy Metals Present in Spent Hydrotreating Catalysts

This paper presents the results of an investigation on the treatment of two industrial solid wastes produced by oil refineries in Singapore, namely Ni∕Mo∕γAl2O3 and Co∕Mo∕γAl2O3. Calcination at 500°C was effective in removing carbon and sulfur in both wastes followed by generation of heavy metal oxides. A two-stage leaching process was successful in removing 44% nickel, 77% cobalt, and 83% molybdenum. However, toxicity characteristic leaching procedure leaching tests for spent catalyst residues of Co∕Mo∕γAl2O3 and Ni∕Mo∕γAl2O3 after the two-stage leaching process showed that the concentration of Mo, Co, and Ni in the leachate exceeded the allowable limits. Finally, the residues, when subjected to an enhanced binder stabilization treatment with marine clay, produced a commercial-value brick made of up to 30% by weight spent catalysts. It is believed that stabilization can be achieved through either encapsulation whereby the clay forms a matrix around the heavy metals to prevent leaching or incorporation in which the heavy metals actually become part of the stabilizing matrix.     

Effect of Calcium on Lead in Soft-Water Distribution Systems

Meeting the lead rule action level for drinking water can be difficult for soft-water systems. One concern in these systems is the formation of particulate or colloidal lead that is difficult to remove from the aqueous phase. In this preliminary study, batch and pipe-loop systems are used to assess the effect of calcium addition on lowering the concentration of particulate or colloidal lead. The addition of calcium at levels as low as 5 mg∕L reduced zeta potential of lead-bound colloids and in some cases resulted in a reduction of total Pb concentration.     

Enhanced Solubility and Biodegradation of Naphthalene with Biosurfactant

Biosurfactant was produced by fermenting kerosene and used vegetable oil using a Pseudomonas sp. under nonsterile conditions. The biosurfactant at a concentration of 0.5 g∕L and pH of 10.5 lowered the surface tension of water to 25 mN∕m. The biosurfactant was used to enhance the solubility of naphthalene, and the results are compared to an anionic (sodium dedecyl sulfate) and a nonionic (Triton X-100) surfactant. The biosurfactant (5 g∕L at pH of 7) enhanced the solubility of naphthalene to more than 30 times its aqueous solubility. Solubilized naphthalene in Triton X-100 and biosurfactant solutions was biodegraded by the same microorganism that produced the biosurfactant. Naphthalene solubilized in biosurfactant and Triton X-100 (400–600 mg∕L) was biodegraded in 40 days and 100 h, respectively. Naphthalene in the amount of 30 mg∕L was degraded by the Pseudomonas sp. in 2 days. The biosurfactant was also biodegraded during the biodegradation of naphthalene, but this was not the case with Triton X-100. The biodegradation of the biosurfactant appeared to compete with the biodegradation of naphthalene. Sodium dedecyl sulfate inhibited the biodegradation of naphthalene at the conditions studied.     

EDTA络合滴定法联合测定硅钙钡镁合金中钙钡镁

建立了一种快速测定硅钙钡镁合金中钙、钡和镁含量的分析方法。以盐酸、硝酸和氢氟酸分解试样,高氯酸冒烟除去残余的盐酸、硝酸和氢氟酸,经过氨水沉淀分离铁、铝等干扰元素后,在pH 10的NH₃·H₂O-NH₄Cl缓冲体系中,以邻甲酚酞指示滴定终点, EDTA络合滴定法测定钙镁合量;在pH≥12的氢氧化钾缓冲体系中,分别以钙指示剂和钙黄绿素-茜素混合指示剂指示滴定终点, EDTA滴定法分别测定钙及钙钡合量。根据钙钡合量与钙含量的差值和钙镁合量与钙含量的差值,可分别得到钡和镁含量。经氨水沉淀后试液中残余的铁、铝和其他干扰离子用三乙醇胺掩蔽,钡对滴定钙和钙镁合量以及镁对滴定钙和钙钡合量的干扰分别通过生成硫酸钡和氢氧化镁沉淀的方法消除。建立的方法用于实际硅钙钡镁合金中钙、钡和镁测定,测定值与对照方法测定值相符,钙、钡和镁的相对标准偏差分别为0.38%、1.9%和1.9%。     

铬天青S-正丙醇-氯化钠体系萃取分离铝

研究了铬天青S-正丙醇-氯化钠体系析相萃取分离和富集铝的行为及与一些金属离子分离的条件,结果表明,氯化钠能使正丙醇的水溶液分成两相,在分相过程中,Al³⁺和铬天青S(CAS)生成的Al(CAS)₂^-与质子化正丙醇C₃H₇OH₂⁺ 形成的缔合物［Al(CAS)₂^-］［C₃H₇OH₂⁺］能被正丙醇相完全萃取,当溶液pH值为4,正丙醇、铬天青S和氯化钠的浓度分别为30 %（V/V）、5.0×10^-4 mol/L和0.17 g/mL时,Al³⁺的萃取率达到97.8%以上,而Ru³⁺、Ir⁴⁺、Pd²⁺、Fe²⁺、Ni²⁺、Co²⁺、Cr³⁺、Mg²⁺、V⁵⁺ 和 Ag⁺基本不被萃取,实现了Al³⁺与上述金属离子的分离。对合成水样和镍铬铝合金中铝的分离和测定,结果满意。该方法在微量铝的分离和富集分析中有一定的实用价值。     

Roll-Bonded Tri-Layered Mg/Al/Stainless Steel Clad Composites and their Deformation and Fracture Behavior

The deformation and fracture behaviors of roll-bonded tri-layered Mg/Al/stainless steel (SST) composite plates were studied. Brittle interfacial reaction compounds were observed at the Mg/Al interface upon annealing at and above 573 K (300 °C), whereas no visible interfacial reaction compounds were observed at Al/SST interfaces even after annealing up to 673 K (400 °C). The strength of the tri-layered Mg/Al/SST clad plates is in close agreement with those calculated from the strength data of the separated Mg, Al, and ST layers using the rule of mixture. The fracture strain components of the tri-layered clad in the absence of brittle interfacial intermetallic layer far exceed those calculated based on the fracture strain data of separated Mg, Al, and SST sheets. The enhanced ductility of the clad composites is due to the suppression of the localized deformation in a metallic layer by other metallic layers caused by the mutual constraint imposed by an adjacent layer. On the other hand, the fracture strain was found to be reduced in the presence of intermetallic layers between the metallic substrates. Cracks perpendicular to the stress axis were observed in the intermetallic compound layer between Mg and Al, inducing the localized slip in the vicinity of intermetallic cracks and premature fracture of the Mg alloy layer.     

The composition of lipids in intestinal digesta of young pigs receiving diets containing tallow and tallow fatty acids

Three semipurified diets containing a low level of fat or 10 percent of either beef tallow or beef tallow free fatty acids were fed to young pigs. Jejunal digesta was sampled 1.5, 2.5, 3.5, and 4.5 h after feeding by aspiration through tubes leading from the jejunal lumen to the exterior. The samples were forced through Millipore filters (1 x 10(-7) m pore size) to separate aqueous phase and oil phase lipid. The total and aqueous phase lipid was separated into triglyceride, monoglyceride, and free fatty acid, and the fatty acid composition of each fraction determined. The concentration of aqueous phase lipid was not influenced by diet, although the concentration of the oil phase lipid was generally higher for the addition of fat to the diets; the increase was greater for the beef tallow free fatty acid diet than for the beef tallow diet. Free fatty acids were the predominant component of the aqueous phase lipid along with some monoglyceride and traces of triglyceride. The major component of the oil phastions of triglyceride and monoglyceride. These must have been derived from endogenously secreted lipid in the case of the tallow fatty acid diet. Thus, the lower digestibility of completely hydrolyzed beef tallow than of conventional beef tallow was not due to an absence of monoglyceride in the intestinal lumen. The proportion of stearic acid in the jejunal digesta was greater than in the dietary lipid, whereas there were lower proportions of palmitic and oleic acids in the jejunal digesta than in the diet; the effect being most pronounced for the tallow free fatty acid diet. The ratio of oleic to palmitic acid in the aqueous phase was less than in the lipid phase suggesting preferential uptake of oleic acid from the micelle by the intestinal mucosa.     

在抗坏血酸存在下正丙醇-碘化钾-硫酸铵体系萃取分离锑（Ⅲ）的研究

研究了在抗坏血酸存在下正丙醇-碘化钾-硫酸铵体系萃取分离和富集Sb（Ⅲ）的行为及与一些金属离子分离的条件。结果表明,硫酸铵能使正丙醇的水溶液分成两相,在分相过程中,Sb（Ⅲ）与碘化钾生成的(SbI4-)与质子化正丙醇(C3H7OH2+)形成的缔合物［SbI4-］［C3H7OH2+］能被正丙醇相完全萃取。当正丙醇、碘化钾和硫酸铵的浓度分别为30%(V/V)、0.40 mol/L、0.20 g/mL时,Sb（Ⅲ）的萃取率达到96.9%以上,Pb（Ⅱ）,Mn（Ⅱ）,Fe （Ⅲ）,Zn（Ⅱ）,Al（Ⅲ）,Cr（Ⅲ）,Ni（Ⅱ）,Cu（Ⅱ）和Mg（Ⅱ）基本不被萃取,实现了Sb（Ⅲ）与上述金属离子的分离。     

Reduction of Indoor Radon by Air Cleaning—Case Study

A field study was conducted over an intermittent period of 2.5 years to determine whether air cleaning, using a portable high efficiency particulate air filter air cleaner with an activated carbon filter, was a viable method of reducing indoor radon levels. Past studies showed that air cleaners could reduce radon and∕or radon progeny concentrations. The data collected in this study showed that the air cleaner did not reduce radon levels and so was not an effective mitigation device. The data also showed that above radon levels of 6 pCi∕L there was a strong positive linear correlation to moisture content. Below 6 pCi∕L there was essentially no correlation. Radon concentrations were determined using EPA approved commercial test kits that were occasionally run in duplicate. In these cases it was found that there was good reproducibility between the test kits over a range of levels from 1.1 to 14.5 pCi∕L, with the average difference being under 10%.     

LEPA and Spray Irrigation for Grain Crops

Two low energy precision application (LEPA) sprinkler methods (double-ended socks and bubblers) and two spray sprinkler methods (low-elevation spray application and overhead spray) were used to irrigate corn, grain sorghum, and winter wheat in the Southern High Plains. For full or 100% irrigation, sufficient 25-mm applications were applied to maintain soil water at non-yield-limiting levels determined in earlier research with the three crops. Deficit-irrigated treatments were irrigated on the same days as the control treatment in 25 or 33% increments of the fully irrigated amount. Irrigation water was applied to or above alternate furrows with a three-span lateral move irrigation system. Corn and sorghum were grown on beds and furrows with all furrows diked, and wheat was flat-planted without basin tillage. Grain yields increased significantly with irrigation amount (p ≤ 0.05) for all crops during all years. With full irrigation, grain yields varied little among the sprinkler methods, and yields averaged 13.5, 8.9, and 4.6 Mg∕ha for corn, sorghum, and wheat, respectively. With the 25 and 50% deficit irrigation amounts, sorghum yields with LEPA irrigation were 1.1 Mg∕ha larger than with the two spray methods. For 75% irrigation of sorghum and for deficit irrigation of the other two crops, there was little yield difference between the LEPA and spray sprinkler methods. Grain yields were significantly correlated with seasonal water use with regression coefficients of 2.89, 1.84, and 0.915 kg∕m3 for corn, sorghum, and wheat, respectively.     

Bioremediation Kinetics of Crude Oil at 5°C

This bench scale experiment investigated the mineralization of crude oil at cold temperatures. Biodegradation rates of Alberta Sweet Mix crude oil at 5°C and at ambient temperatures (21°C) were compared. The experimental design consisted of 14 soil columns. Off-gas samples for each column were analyzed every second day using a gas chromatograph to determine CO2 production rates. The run lasted for 219 days, at which time the soil columns were sacrificed for analysis. Oil mineralization values were modeled by a number of methods, including CO2 production determination from GC measurements and gravimetrically determined hydrocarbon loss using soxhlet extraction. The results of the experiment suggested that temperature only affected the biodegradation rates of crude oil in the initial phase of the biodegradation process. After approximately 3 months, the degradation rates of crude oil at 5°C and 21°C were similar at about 11 mg hydrocarbon∕kg dry soil∕day. The conclusion of this study was that significant mineralization of Alberta Sweet Mix crude oil can occur at cold temperatures.     

Reduced-Runoff Irrigation of Sudan Grass Hay, Imperial Valley, California

Sudan grass is a moderately salt-tolerant annual that is capable of substantial osmotic adjustment under high soil salinity conditions, but little is documented about its actual water use and yield under saline conditions. We estimate water use and evaluate the effects of “reduced-runoff” irrigation on soil salinity associated with Sudan grass hay production during a three-year field study (1996–98) in the Imperial Valley, California. The reduced-runoff irrigation method relies on the application of a simplified volume-balance surface irrigation model, and can result in negligible surface runoff; however, its use may have adverse impacts on soil salinity. Despite an anticipated salinity-induced yield reduction of about 15% associated with an average soil salinity of 6 dS∕m (0–0.6 m depth), use of the reduced-runoff method resulted in satisfactory crop yields, practically no tailwater runoff, and a slight decrease from the initial average profile soil salinity. The average applied water depth and estimated consumptive use (ETc) during the project were 1,019 and 935 mm, respectively, resulting in an average hay yield of 14.4 Mg∕ha versus the 1996–98 county average of 12.6 Mg∕ha. The project average ETc/ET0 and yield∕ETc ratios of 0.73 and 15.5 kg∕ha?mm, respectively, were approximately 15% less than those estimated from water-use-efficiency studies, probably as a result of salinity-induced hay yield reduction.     

Volatile Organic Compounds in New Automobiles: Screening Assessment

Four new vehicles were tested to assess the nature (constituents and concentrations) of volatile organic compounds (VOCs) associated with new vehicle interiors. The total VOC (TVOC) concentration within the interior of one vehicle (minivan) was 7,500 μg∕m3 on the first day of sampling (second day after purchase), approximately two orders of magnitude higher than the outdoor TVOC concentration. The TVOC concentration in the minivan was observed to decay significantly with time, with an approximate 90% reduction in concentration after three weeks of testing. The other three vehicles had TVOC concentrations that ranged from 300 to 600 μg∕m3 on the first day of testing. Over sixty chemicals were identified inside the interiors of the four vehicles. Compounds identified in all four vehicles and their GC∕MS area percent ranges were toluene (2.2–12.6%), ethylbenzene (0.5–2.2%), xylene (2.4–10.7%), and undecane (0.8–7.5%).     

New Data on the Mineralogy of Chromite from the Nuggihalli Schist Belt, Western Dharwar Craton, Karnataka, India:Petrogenetic Implications

The occurrence of rhythmic layering of chromite and host serpentinites in the deformed layered igneous complexes has been noticed in the Nuggihalli schist belt (NSB) in the western Dharwar craton, Karnataka, South India. For this study, the chromitite rock samples were collected from Jambur, Tagadur, Bhakatarhalli, Ranganbetta and Byrapur in the NSB. Petrography and ore microscopic studies on chromite show intense cataclasis and alteration to ferritchromite. The ferritchromite compositions are characterized by higher Cr number (Cr/[Cr+Al]> (0.68-0.98) and lower Mg number (Mg/[Mg+Fe]) (0.33-0.82) ratios in ferritchromite compared to that of parent chromite. The formation process for the ferritchromite is thought to be related to the exchange of Mg, Al, Cr, and Fe between the chromite, surrounding silicates (serpentines, chlorites), and fluid during serpentinization.     

H2O2∕UV-C and Fe2+∕H2O2∕UV-C versus TiO2∕UV-A Treatment for Reactive Dye Wastewater

This study investigated the advanced oxidation of commonly used reactive dyestuffs in exhausted dye-bath effluents in homogeneous (H2O2∕UV-C and photo-Fenton) and heterogeneous (TiO2∕UV-A) media. Photocatalytic treatment efficiencies of two different TiO2 powders (PC 500 and Mikroanatas) and the platinized Degussa P25 were compared with that of the more well-known Degussa P25 in varying pH media. Treatment performance was strongly affected by the initial H2O2 concentration for H2O2∕UV-C and photo-Fenton oxidation systems, whereas for the TiO2∕UV-A process only PC 500 TiO2 powder, an anatase crystal phase of the semiconductor, exhibited a significantly pH-dependent reaction efficiency. The decolorization rate followed the order of Fenton∕UV-C > Pt-P25∕UV-A > Mikroanatas∕UV-A > P25∕UV-A > PC 500∕UV-A > H2O2∕UV-C, whereas the decreasing order for total organic carbon reduction was Fenton∕UV-C > H2O2∕UV-C > Mikroanatas∕UV-A > Pt-P25∕UV-A > P25∕UV-A > PC 500∕UV-A for the studied reaction conditions. Removal of optical density at 254-nm wavelength ranged between 75 and 96%.     

Microstructure evolution and densification behaviour of powder metallurgy Al–Cu–Mg–Si alloy

ABSTRACT

An Al–Cu–Mg–Si alloy was prepared by conventional press-sintering powder metallurgy using elemental Al powder. The phase transformation process of Al–Mg, Al–Si alloy and Cu during the sintering process was investigated in details. It was found that a series of phase transitions take place in the alloy to disrupt the oxide film of Al particle and enhance the densification process. The relative density of the sintered samples reached 98%. A new Al–Mg–Cu–O compound was found at the grain boundaries except the MgAl₂O₄ phase, it is speculated that the disruption of the oxide film was also associated with the other alloy compositions except for Mg. Furthermore, no detectable AlN compound was found at the grain boundary region although sintering with flowing nitrogen atmosphere, which is benefit from the high density of the green compact and the excellent wettability between the liquid phase and the aluminium.     

Temperature and SRT Effects on Aerobic Thermophilic Sludge Treatment

Laboratory-scale experiments were conducted to determine optimum sludge residence time (SRT) and temperature of aerobic thermophilic pretreatment (ATP) of mixed sludge (thickened waste activated sludge and primary sludge) to achieve maximum pathogen reduction and best process performance. 4-L laboratory-scale ATP reactors were operated at SRTs of 0.6, 1.0, and 1.5 days and temperatures of 55, 58, 62, and 65°C. ATP at temperatures ≥62°C and SRT ≥0.6 day reduced the feed sludge fecal coliform density from 107 MPN∕g total solids (TS) to <104 MPN∕g TS. Salmonella in the feed sludge was reduced to <1 MPN∕4 g TS from 2 to 18 MPN∕4 g TS by ATP at temperatures ≥55°C and SRT ≥0.6 day. ATP was able to increase sludge volatile acids concentration by 100–200% over the feed sludge volatile acid concentration and to reduce sludge supernatant chemical oxygen demand from 20,000 to 22,000 mg∕L in the feed to 13,000–17,000 mg∕L in the ATP reactor. Volatile solids reduction by ATP increased from 25 to 40% when SRT was increased from 0.6 to 1.5 days, and a 5% increase in volatile solids reduction was seen at SRTs of 0.6, 1.0, and 1.5 days when ATP temperature was increased from 55 to 65°C.     

Reduced-Runoff Irrigation of Alfalfa in Imperial Valley, California

This paper assesses the potential of the “reduced-runoff” surface irrigation method for clay soils to limit tailwater runoff and evaluate its impacts on crop production and soil salinity throughout a 3-year alfalfa hay production cycle in the Imperial Valley. Despite moderately saline field conditions, tailwater runoff was reduced to <2%, thereby reducing the annual water application by approximately 28% with no loss in hay yield or quality in comparison to countywide averages. The valley average applied-water yield efficiency (yield∕applied water) was increased from 8.9 to 15.2 kg∕ha-mm. When corrected for yield reduction due to salinity conditions (i.e., ～21 kg∕ha-mm), this latter value is comparable to reported maximum alfalfa water-use efficiency (～20 kg∕ha-mm). Soil salinity accumulated (from 6 to 14 dS∕m) at the 0.9–1.5 m depth interval of the soil profile, particularly in the lower 15% of the border checks by the end of the study. However, disking, a single leaching irrigation, and sweet corn production after termination of the alfalfa were adequate to reclaim the soil.     

复杂镍浸出液萃取净化的研究

以D2EHPA为萃取剂,从钼镍矿的复杂镍浸出液中萃取分离锌、铜。考察了萃取平衡时间、D2EHPA体积浓度、相比(O/A)、料液pH对萃取分离锌、铜效果的影响,确定了D2EHPA萃取锌、铜的最佳条件。室温下萃取除杂的最佳工艺条件为:萃取平衡时间3 min,D2EHPA的体积浓度20%,相比1∶1,料液pH=2.0,一级萃取率锌为89.5%,铜为11.0%。负载有机相经1 mol/L的H2SO4反萃,锌、铜和镍均可完全反萃。经三级逆流萃取可将料液中锌降低到0.01 g/L,萃取率达98.9%。