Residual Aluminum Research Articles

Water quality produced by polystyrene granules as a media filter on rapid filters

Many devices are used to improve the performance of rapid filters, increasing the filter run and reducing the velocity of the wash water filter with the use of multiple layers and the adoption of different filter materials. This study constructed a descending rapid filter utilizing polystyrene granules as a new filter element; this was compared to a sand and anthracite descending rapid filter. The filter performance was compared in terms of water quality, turbidity, apparent and true color, conductivity, total dissolved solids, temperature, pH, residual aluminum, and removal of cyanobacterium (Cylindrospermopsis raciborski) under the same operating conditions of filtration. The sand and anthracite filter reached the greatest filtration run, but the water quality of the polystyrene filter had a similar quality to the sand and anthracite filter. Furthermore, the filter containing polystyrene granules as a media filter can represent savings with decreased wash water and the construction of reservoirs with a lower hydraulic load.

Characterization and performance of poly-silicic-cation coagulant in treatment of recycled paper wastewater

Tertiary treatment of pulp and paper wastewater has become increasingly pressing since stricter legislations were issued by the central government and some provincial governments in China. Coagulation process after biological treatment has been regarded as a techno-economically feasible technology for the high quality effluent. In this paper, a study on preparation and characterization of poly-silicic-cation coagulants (PSiCs) with different Si/(Al + Fe) molar ratios is described. X-ray diffraction, infrared spectra, ultraviolet/visible absorption scanning, and microscopic imaging were used as measures for characterization. Coagulant performance was evaluated using it in papermaking wastewater treatment. The results showed that new complex compounds had formed in the PSiC polymers and the optimal Si/(Al + Fe) molar ratio for the coagulant polymerization was about 0.9, at which the polymerization degree was highest. The content of ionic polymerized bonds and branch-like PSiC units would decrease when the molar ratio was lower or higher than 0.9. The highest efficiency appeared when PSiC0.9 was used in the wastewater treatment, rather than PSiC0.6 and PSiC1.5. The results also showed that concentrations of turbidity, COD, color, and residual aluminum in the PSiC treated effluent were lower than that from coagulation tests using traditional coagulants.

Fluoride removal from water using high-activity aluminum hydroxide prepared by the ultrasonic method

Ultrasonically prepared Al(OH)3 has a high defluoridation capacity and a low residual aluminum concentration in drinking water after defluoridation.

Solution‐Grown Zn/Al Layered Double Hydroxide Nanoplatelets onto Al Thin Films: Fine Control of Position and Lateral Thickness

We have grown nanostructured films of Zn/Al Layered Double Hydroxide (LDH) on different substrates by combining the deposition of an aluminum micropatterned thin layer with a successive one‐step room‐temperature wet‐chemistry process. The resulting LDH film is made of lamellar‐like nanoplatelets mainly oriented perpendicular to the substrate. Since the aluminum layer acts as both reactant and seed for the synthesis of the LDH, the growth can be easily confined with submicrometric‐level resolution (about ±0.5 μm) by prepatterning the aluminum layer with conventional photolithographic techniques. Moreover, we demonstrate real‐time monitoring of the LDH growth process by simply measuring the resistance of the residual aluminum film. If the aluminum layer is thinner than 250 nm, the morphology of LDH nanoplatelets is less regular and their final thickness linearly depends on the initial amount of aluminum. This peculiarity allows accurately controlling the LDH nanoplatelet thickness (with uncertainty of about ±10%) by varying the thickness of the predeposited aluminum film. Since the proposed growth procedure is fully compatible with MEMS/CMOS technology, our results may be useful for the fabrication of micro‐/nanodevices.

Preparation and Mechanism of a New Enhanced Flocculant Based on Bentonite for Drinking Water

Bentonite is characterized by the large specific surface, good adsorption, ion exchange ability, and nontoxicity. An enhanced bentonite base composite flocculant (BTA) can be prepared from treating the calcium base bentonite and compositing various functional additives. Bentonite was firstly treated by citric acid, then the talc and activated carbon turned to be acid part and simultaneously the part that was treated by sodium bicarbonate and calcium hydroxide turned to be alkaline part, and finally the acid bentonite part and alkaline bentonite part were mixed up with preground powder of polymeric chloride aluminium (PAC), cationic polyacrylamide (CPAM), ferrous sulfate, and aluminum sulfate, and after all of the processing flocculant BTA was obtained. The optimum preparation process of flocculant BTA has shown 29.5% acid bentonite part, 29.5% alkaline bentonite part, 15% PAC, 1% CPAM, 5% ferrous sulfate, and 20% aluminum sulfate. BTA was used to treat drinking water with high turbidity and metal ion in Karamay City, Xinjiang. The treated water was surely up to the drinking water standard of China in decolorization rate, deodorization rate, heavy metal ion removal rate, and so forth, and contents of residual aluminum ions and acrylamide monomer in drinking water were considerably decreased.

Synthesis and coagulation performance of composite poly-aluminum-ferric-silicate-chloride coagulants in water and wastewater

The aim of this work was to study the combination of an inorganic pre-polymerized coagulant (polyaluminum chloride [PACl]) with ferric species and polysilicic acid in various mixing orders Al/Fe/Si and OH/Al molar ratios, by applying two polymerization techniques for the production of a unique reagent, representing a more efficient coagulant than the respective commercially available (PACl-18) or laboratory-prepared (PACllab) for water or wastewater treatment. Several of coagulants’ derivatives were prepared and were examined by jar tests for the treatment of simulated surface water, contaminated by clay particles (turbidity) and humic acid (natural organic matter); pH, turbidity, UV254 nm absorbance, and residual Al were measured in the treated water. PSiFAC1.5:10:15 prepared by the co-polymerization technique was found to be the most efficient coagulant from all the tested compounds; in addition, no flocculant aid (polyelectrolyte) was required with this product. Low coagulant doses, about 1.5–2 mg/L were required for the reduction of turbidity values to lower than 1 NTU; furthermore, PSiFAC1.5:10:15 resulted in low residual aluminum concentration (about 140 μg Al/L). The most effective coagulants obtained were also used for the treatment of tannery wastewater to evaluate their performance and it was observed that high turbidity removal (~99%) was obtained at doses of about 100 mg/L. The most effective coagulants are under study for their potential use to alleviate membrane fouling in MBRs.

Evaluation of performance of different aluminium-based coagulants and aids in river water clarification

Coagulation and fl occulation is one of the most effective, economic and convenient method for raw water clarifi cation. In recent times, different hydrolysing coagulants, particularly aluminium-based ones are in wide use. In the present study, different aluminium-based salts, polymer and coagulant aid were used to observe their effectiveness as well as side effects, if any. Turbidity was the prime criterion for clarifi cation of the raw water; however, the potentially hazardous residual aluminium was also given due importance. Poly-aluminium chloride (PACl) enhanced the performance of the potash alum when used in tandem, whereas bentonite powder used as coagulant aid proved ineffective in improving the performance of the potash alum with respect to the removal of the turbidity. PACl when used alone or in tandem with potash alum showed character

Structures and Optical Properties of Anodic Aluminum Oxide Thin Films

Low refractive index materials (n<1.3) are not common in nature. However, they are essential for antireflection coatings. In this study porous anodic aluminum oxide (AAO) on glass substrate was fabricated by electrochemical oxidation and subsequent etching. The pore size was modulated from less than 80 nm to more than 250 nm. The pore depth was controlled by electrochemical anodization and/or chemical etching time. It is challenging to effectively quantify the pore structures and the optical properties of such porous materials. Using spectroscopic ellipsometry, the authors showed that the AAO materials had tunable refractive index from 1.25 to 1.40, which is ideal for antireflection coating on glass (n=1.54). In addition, quantitative information on the AAO film porosity, profile structure, film thickness, dielectric constants, and roughness was also derived from the ellipsometry analysis. It was shown that the as-fabricated AAO film included trace amount of residual metal aluminum with an effective thickness ~0.28 nm.

The combined effects of zinc stannate and aluminium diethyl phosphinate on the burning behaviour of glass fibre-reinforced, high temperature polyamide (HTPA)

The effect of changing the ratio of aluminium diethyl phosphinate (as Exolit OP1230) and zinc stannate (as Flamtard S) present within a glass-reinforced high temperature polyamide (HTPA/GF) at a constant total flame retardant level of 15 wt% is shown to have fire performance properties that depend on the ratio of both these agents. Aluminium diethyl phosphinate (AlPi) alone at 15 wt% gives LOI > 40 vol% and a V-0 rating. The introduction of zinc stannate (ZS) at levels up to 3.75 wt% maintains the LOI at about 40 vol% and the V-0 rating. Similarly, glow wire ignition temperatures and cone calorimetry results, in terms of minimal peak heat release rate, show that optimum fire performance also occurs at the [ZS] ≤ 3.75% and [AlPi] ≥ 11.25% condition. Smoke generation reduces only slightly when highest levels of AlPi are present compared with the HPTA/GF sample and then reduces further as the ratio [ZS]/[AlPi] increases. Tensile and impact properties are also optimal for the [ZS] ≤ 3.75 wt% and [AlPi] ≥ 11.25 wt% condition. At the mechanistic level, TGA studies show that for HPTA/GF, the presence of oxygen increases char residue in the 450–550 °C region compared to when heated under nitrogen. Air oxidation further increased residues above 450 °C when AlPi is present and confirms other published work that the reported volatilization occurring during pyrolysis under nitrogen is now in competition with its oxidation to aluminium phosphate. Thus residues above 450 °C in air comprise both increased char from HTPA plus residual aluminium phosphate with the latter remaining above 600 °C after the former has oxidized.

Behavior of Aluminum Based Coagulants in Treatment of Surface Water–Assessment of Chemical and Microbiological Properties of Treated Water

Abstract Pre-polymerized inorganic aluminum coagulants have high efficiency in reducing turbidity, total, dissolved, biodegradable organic carbon and microbiological content of surface waters used for drinking, while obtaining low concentrations of residual aluminum after the coagulation phase. Correlation between turbidity raw water and coagulant dose is logarithmic being influenced by temperature and organic content of surface waters. The coagulant’s effect on the organic content of the raw water is closely related to the microbiological concentration and can thus determine the mathematical correlations between the two types of parameters after the coagulation-flocculation stage that can be used to assess the water biostability coagulant action.

Influence of shear force on floc properties and residual aluminum in humic acid treatment by nano-Al13

The impacts of various shear forces on floc sizes and structures in humic acid coagulations by polyaluminum chloride (PACl) and nano-Al13 were comparatively studied in this paper. The dynamic floc size was monitored by use of a laser diffraction particle sizing device. The floc structure was evaluated in terms of fractal dimension, analyzed by small-angle laser light scattering (SALLS). The effect of increased shear rate on residual Al of the coagulation effluents was then analyzed on the basis of different floc characteristics generated under various shear conditions. The results showed that floc size decreased with the increasing shear rate for both Al13 and PACl. Besides, floc strength and re-formation ability were also weakened by the enhanced shear force. Al13 resulted in small, strong and better recoverable flocs than PACl and moreover, in the shear range of 100–300 revolution per minute (rpm) (G=40.7–178.3s−1), the characteristics of HA-Al13 flocs displayed smaller scale changes than those of HA-PACl flocs. The results of residual Al measurements proved that with shear increased, the residual Al increased continuously but Al13 presented less sensitivity to the varying shear forces. PACl contributed higher residual Al than Al13 under the same shear condition.

Removal of phosphorus and residual aluminium with the simultaneous use of chitosan and alum on the effluent of an MBBR biological system during start-up

Physico–chemical treatment with aluminium salts is a common practice to remove total phosphorus (TP) from wastewaters. However, the use of alum can increase the residual aluminium concentration both in the effluent and biosolids. Chitosan, an alternative coagulant, does not allow for the removal of TP below the requirement level when lower than the soluble phosphorus fraction of the water. Hence, simultaneous dosage of alum and chitosan solutions was evaluated on the effluent of a newly installed MBBR (moving bed biofilm reactor) system for residual TP and aluminium removal. At alum optimal dosage, the most effective chitosan solution generated: 1) an optimal dosage zone for which residual TP and aluminium concentrations were minimal; 2) maximal abatements for TP and aluminium that reached 35 and 85%, respectively, the concentrations observed with alum only. Also, the fraction of residual aluminium in the biosolids was increased, particularly from 84 to 98% at optimal chitosan dosage.

Electrochemical Oxidation as Vertical Structuring Tool for Ultrathin (d < 10 nm) Valve Metal Films

Stepwise potentiostatic oxidation is used to reduce the thickness of thin aluminum and tantalum films from an initial thickness of 10 nm down to 2 nm. The thicknesses of the oxide and the residual metal are adjusted by the finite potential of an electrochemical oxidation procedure which consumes the initially 10 nm thick metal films. The metal–metal oxide interfaces are smooth and sharply defined. The metal consumption and oxide formation are proportional to each other by the ratio of their specific densities. This enables the derivation of a metal consumption factor for the residual metal film. Residual aluminum films show a significant increase of the specific resistivity with decreasing film thicknesses. This can be explained by modified electronic transport in the residual aluminum for example by changed electronic scattering processes at the metal–metal oxide interface or in the metal. Residual tantalum films show a weaker dependence of the specific resistivity down to 3 nm pointing to only slightly changed transport properties for electrons in the thin tantalum layers.

Toxicity evolution of alum-coagulated municipal wastewater to sea urchin embryogenesis and fertilization

The alum-based coagulation process is a worldwide treatment method in industrial and municipal wastewater (MW) management. In the present study, alum-coagulation was performed on wastewater from the MW plant located south of Naples, Italy, to evaluate any negative impact of MW on marine biota by means of sea urchin bioassays. A series of Jar test experiments (100 rpm for 1 min, 30 rpm for 20 min, and 30 min for settling) was performed using 150 and 450 mg/L of alum concentrations at pH ranging from 5 to 7 and room temperature (20° ± 2°C). Raw and alum-coagulated wastewater samples were analyzed for their COD and TSS, and residual aluminum (RA) concentrations. Toxicity testing of samples (diluted to 1%) by Sphaerechinus granularis sea urchin bioassays (collected in Naples bay) was evaluated to meet the following specifications: (a) acute and/or developmental toxicity, (b) changes in fertilization success, and (c) cytogenetic abnormalities. The results provided the following evidences: (i) the coagulation process at a 150 mg/L alum level in the SG plant was sufficient to meet the discharge standards; (ii) RA was found significantly related to alum dose used in coagulation process and raw wastewater alum concentration; (iii) sea urchin bioassays provided evidence for both embryo toxicity in raw wastewater to a lesser extent, and in alum-coagulated Jar test supernatants, at elevated extent, at a 1% concentration; and (iv) no statistically significant spermiotoxic or cytogenetic effect was observed. Altogether, the results highlighted the influence of wastewater characteristics on developmental toxicity, such as pH-related Al(III) speciation and alum complex formation in wastewater.

Influence of the residual aluminum content on the grain size and the mechanical properties of 20G steel

The article presents the results of detecting the possible influence of the residual aluminum content on the grain size and the mechanical properties of the 20G steel produced at ZAO VMZ Krasny Oktyabr.

Characteristics of residual metals from phosphorus removal in sewage treatment plants around Paldang lake, Korea

The abundant use of chemicals to remove phosphorus in water could pose a problem to the safety of drinking water. In this study, we investigated the amount of residual aluminum and iron remaining in river. Paldang lake consists of two major tributaries (North Han River and South Han River) and one minor tributary (Gyung-an Stream). As a result of a total inspection on 45 phosphorus removal treatment plants in Paldang watershed of Han River, it was found that 39 treatment plants used aluminum-related coagulants while six treatment plants used iron salts. We investigated aluminum and iron concentrations in influent and effluent from six representative phosphorus removal treatment plants (A–F) in three tributaries and found that iron concentrations in A and C and aluminum concentrations in B and D exceeded drinking water standards. The background concentrations of aluminum and iron not affected by treatment plants nearby were 0.04–0.20 and 0.09–0.11 mg/L, respectively. In sediments, the background concentrations of aluminum and iron were 70.9–86.3 and 37.2–51.3 g/kg, respectively. Aluminum and iron concentrations in six representative treatment plants in the three tributaries were 16.9–64.9 and 17.1–75.3 g/kg, respectively. Since the pH range in sediment was 6.8–7.8, the possibility to leach aluminum and iron was low. Among other water quality parameters, turbidity was significantly correlated to the concentration of aluminum and iron. Finally, the concentrations of aluminum and iron of this study in Korea are higher than those of Japan and Taiwan.

Virus removal by an in-line coagulation–ceramic microfiltration process with high-basicity polyaluminum coagulation pretreatment

The ability of in-line coagulation pretreatment with high-basicity polyaluminum chloride (PACl) coagulants to enhance virus removal by ceramic microfiltration (MF) was examined by comparing virus removal efficiencies from water pretreated with PACl-2.2 (basicity 2.2) and PACl-2.5 (basicity 2.5) versus alum, a synthetic aluminum chloride (AlCl3) solution, and two commercially available PACls, PACl-1.5 and PACl-1.8. The virus removal ratios for AlCl3, alum, PACl-1.5, and PACl-1.8 decreased markedly when the pH of the treated water shifted from 6.8 to 7.8, but was high at both pHs for PACl-2.2 and PACl-2.5. PACl-2.5 contains Al13 species and possibly Al30 species, and has a high colloid charge density. It removed viruses more efficiently than the other aluminum-based coagulants, not only at neutral pH, but also under weakly alkaline conditions. Moreover, the in-line coagulation–ceramic MF process with PACl-2.5 pretreatment removed not only viruses but also dissolved organic carbon and UV260-absorbing natural organic matter more efficiently and resulted in a lower residual aluminum concentration than did commercially available PACls, especially under weakly alkaline conditions. A combination of coagulation pretreatment with a high-basicity PACl and ceramic MF can provide effective treatment of drinking water over a broader pH range than is possible with commercially available aluminum-based coagulants.

COMPARATIVE STUDY ON PERFORMANCE OF COAGULANTS IN WATER TREATMENT

The study on the performance of different coagulant s in water treatment was carried out using coagulan ts such as alum(C1), Poly aluminium chloride(PAC)(C2) and sodium aluminate(C3 ). The performance was studied with respect to turb idity removal, concentration of residual aluminium and comparative cost of coagulants for treatment of Bhima river wa ter. The performances of these coagulants were studied separately as well as mixture of two coagulants in equal proportions. C1 and C2 were mixed to get coagulant mixture (CM1), C1 and C3 were mixed to ge t CM2, C2 and C3 were mixed to get CM3. The study r eviews that the coagulants C1 and CM3 were found to be more efficie nt with 100% removal of turbidity at turbidities up to 50 NTU. For higher turbidities above 50 NTU, the coagulants C1, C2 and CM1 are found to be more efficient with 100% turbi dity removal. The concentration of residual aluminium is found to be less in CM1 and C2. For turbidities of 200 NTU and 400 NTU with optimum dosages, the concentrations were 0.02mg/L and 0.04m g/L for CM1 respectively.

Improved virus removal by high-basicity polyaluminum coagulants compared to commercially available aluminum-based coagulants

We investigated the effects of basicity, sulfate content, and aluminum hydrolyte species on the ability of polyaluminum chloride (PACl) coagulants to remove F-specific RNA bacteriophages from river water at a pH range of 6–8. An increase in PACl basicity from 1.5 to 2.1 and the absence of sulfate led to a reduction of the amount of monomeric aluminum species (i.e., an increase of the total amount of polymeric aluminum and colloidal aluminum species) in the PACl, to an increase in the colloid charge density of the PACl, or to both and, as a result, to high virus removal efficiency. The efficiency of virus removal at around pH 8 observed with PACl-2.1c, a nonsulfated high-basicity PACl (basicity 2.1–2.2) with a high colloidal aluminum content, was larger than that observed with PACl-2.1b, a nonsulfated high-basicity PACl (basicity 2.1–2.2) with a high polymeric aluminum content. In contrast, although extremely high basicity PACls (e.g., PACl-2.7ns, basicity 2.7) effectively removed turbidity and UV260-absorbing natural organic matter and resulted in a very low residual aluminum concentration, the virus removal ratio with PACl-2.7ns was smaller than the ratio with PACl-2.1c at around pH 8, possibly as a result of a reduction of the colloid charge density of the PACl as the basicity was increased from 2.1 to 2.7. Liquid 27Al NMR analysis revealed that PACl-2.1c contained Al30 species, which was not the case for PACl-2.1b or PACl-2.7ns. This result suggests that Al30 species probably played a major role in virus removal during the coagulation process. In summary, PACl-2.1c, which has high colloidal aluminum content, contains Al30 species, and has a high colloid charge density, removed viruses more efficiently (>4 log10 for infectious viruses) than the other aluminum-based coagulants—including commercially available PACls (basicity 1.5–1.8), alum, and PACl-2.7ns—over the entire tested pH (6–8) and coagulant dosage (0.54–5.4 mg-Al/L) ranges.

Aluminum concentrations of sand filter and polymeric membrane filtrates: A comparative study

The residual aluminum concentration in treated water after aluminum coagulation and solid–liquid separation is one of the key factors in evaluating the effectiveness of water treatments. Polymeric membrane filters have been widely used to operationally define dissolved substances from particulate matter, and have sometimes been employed in laboratories and pilot studies to approximately simulate media filtration. A comparison between media and membrane filters, however, has not yet been fully investigated. This study compared aluminum concentrations in the filtrate after sand bed and membrane filtrations. The aluminum concentration after sand bed filtration was lower than that after filtration using a membrane with a pore size of 0.1μm, irrespective of the membrane material, with one exception. A PVDF membrane with a pore size of 0.1μm produced a similar residual aluminum concentration to that obtained using a sand bed. When the natural organic matter concentration was very low, the aluminum concentration in the PVDF membrane (pore size 0.1μm) and sand bed filtrates was lower than that obtained using other membranes with the same pore size. It is believed that adsorption of dissolved aluminum may enhance aluminum removal by the sand bed and the PVDF membrane when the aluminum exists in an uncomplexed form with natural organic matter.