Coagulation Conditions Research Articles

Controlling harmful algae blooms using aluminum-modified clay

The performances of aluminum chloride modified clay (AC-MC), aluminum sulfate modified clay (AS-MC) and polyaluminum chloride modified clay (PAC-MC) in the removal of Aureococcus anophagefferens were compared, and the potential mechanisms were analyzed according to the dispersion medium, suspension pH and clay surface charges. The results showed that AC-MC and AS-MC had better efficiencies in removing A.anophagefferens than PAC-MC. The removal mechanisms of the three modified clays varied. At optimal coagulation conditions, the hydrolysates of AC and AS were mainly monomers, and they transformed into Al(OH)3(am) upon their addition to algae culture, with the primary mechanism being sweep flocculation. The PAC mainly hydrolyzed to the polyaluminum compounds, which remained stable when added to the algae culture, and the flocculation mainly occurred through polyaluminum compounds. The suspension pH significantly influenced the aluminum hydrolysate and affected the flocculation between the modified clay and algae cells.

A Comparison of Fractal Dimensions of Clay and Humic Acid Flocs under Optimum Coagulation Conditions

A Comparison of Fractal Dimensions of Clay and Humic Acid Flocs under Optimum Coagulation Conditions

Evaluation of the effects of varying the water velocity at the entrance of the contact zone on the performance of a dissolved air flotation (DAF) unit using the image analysis method

For a more efficient design of dissolved air flotation (DAF) units, it is important to deepen our knowledge of the role that each constituent part plays with regard to overall performance. The velocity control of the flocculated water at the entrance (Ve) of the contact zone of DAF units is important because the degree of agitation in this region may affect the size of the flocs and the efficiency of the flotation process. This article shows the results of an experimental study conducted to verify the influence of Ve (and its associated average velocity gradient, Ge) on the performance of a DAF pilot plant (DAFPP) fed with synthetic water. Two different coagulation conditions of the same raw synthetic water were tested, and 11 assays with different Ve values for each condition were performed. The floc size distribution curves regarding two limit situations, the lowest and the highest Ve values, were obtained by using an appropriate image analysis method. The best results were obtained for Ve values ranging from 125 to180 m·h−1, and for Ve values outside this range, the decrease in DAFPP performance was not as substantial as expected.

Production of Eco-friendly Aminotosan®Fertilizer from Waste Livestock Blood using Chitosan Coagulation

The aim of this study was to produce Aminotosan ® fertilizer using optimized chitosan coagulant from waste livestock blood. Amino-acid fertilizer was produced by pretreated livestock blood. Chitosan coagulant was aggregated with amino-acid fertilizer to produce Aminotosan ® . Optimized coagulation conditions were set using chitosan coagulant such as 10% citric acid and 500 ppm chitosan coagulant by analysis of CST and TTF. The efficiency of coagulation by chitosan coagulant under the optimal conditions was better than chemical coagulants. After solid/liquid separation for coagulated amino-acid fertilizer, Aminotosan ® fertilizer which added eco-friendly and aesthetic functions was produced.

Feasibility Study on Electro Coagulation Flocculation for Microalgae Harvesting

Although microalgae are considered as a promising feedstock for biofuels, cost-efficient harvesting of microalgae needs to be significantly improved. In this study, the use of electro coagulation as a more rapid flocculation method for harvesting a freshwater (Scenedesmus dimorphus) microalgae species was evaluated. The results showed that, electro coagulation was shown to be more efficient using an aluminum anode than using an iron anode. And optimum conditions of electro coagulation for harvesting Scenedesmus dimorphus were found. The optimum stirring speed was 100 rpm and optimum pH was 5. Furthermore, the current density which the fastest and highest recovery efficiency is achieved at , while the highest energy efficiency was achieved at . A the rapid and high recovery efficiency indicate that electro coagulation is a particularly attractive technology for harvesting microalgae.

Enhanced Electrical Conductivity in Extruded Single-Wall Carbon Nanotube Wires from Modified Coagulation Parameters and Mechanical Processing.

Single-wall carbon nanotubes (SWCNTs) synthesized via laser vaporization have been dispersed using chlorosulfonic acid (CSA) and extruded under varying coagulation conditions to fabricate multifunctional wires. The use of high purity SWCNT material based upon established purification methods yields wires with highly aligned nanoscale morphology and an over 4× improvement in electrical conductivity over as-produced SWCNT material. A series of eight liquids have been evaluated for use as a coagulant bath, and each coagulant yielded unique wire morphology based on its interaction with the SWCNT-CSA dispersion. In particular, dimethylacetamide as a coagulant bath is shown to fabricate highly uniform SWCNT wires, and acetone coagulant baths result in the highest specific conductivity and tensile strength. A 2× improvement in specific conductivity has been measured for SWCNT wires following tensioning induced both during extrusion via increased coagulant bath depth and during solvent evaporation via mechanical strain, over that of as-extruded wires from shallower coagulant baths. Overall, combination of the optimized coagulation parameters has yielded acid-doped wires with the highest reported room temperature electrical conductivities to date of 4.1-5.0 MS/m and tensile strengths of 210-250 MPa. Such improvements in bulk electrical conductivity can impact the adoption of metal-free, multifunctional SWCNT materials for advanced cabling architectures.

Optimization of coagulation conditions for pretreatment of microfiltration process using response surface methodology

The application of coagulation for feed water pretreatment prior to microfiltration (MF) process has been widely adopted to alleviate fouling due to particles and organic matters in feed water. However, the efficiency of coagulation pretreatment for MF is sensitive to its operation conditions such as pH and coagulant dose. Moreover, the optimum coagulation condition for MF process is different from that for rapid sand filtration in conventional drinking water treatment. In this study, the use of response surface methodology (RSM) was attempted to determine coagulation conditions optimized for pretreatment of MF. The center-united experimental design was used to quantify the effects of coagulant dose and pH on the control of fouling control as well as the removal organic matters. A MF membrane (SDI Samsung, Korea) made of polyvinylidene fluoride (PVDF) was used for the filtration experiments. Poly aluminum chloride (PAC) was used as the coagulant and a series of jar tests were conducted under various conditions. The flux was 90 L/m 2 -h and the fouling rate were calculated in each condition. As a result of this study, an empirical model was derived to explore the optimized conditions for coagulant dose and pH for minimization of the fouling rate. This model also allowed the prediction of the efficiency of the coagulation efficiency. The experimental results were in good agreement with the predictions, suggesting that RSM has potential as a practical method for modeling the coagulation pretreatment for MF.

In-line coagulation with quaternary amine polymer prior to microfiltration of humic-rich water

This work was designed to investigate the feasibility of using a low molecular-weight epichlorohydrin/dimethylamine (epi/DMA) polymer as a primary coagulant for the pretreatment of terrestrial humic-rich water prior to the microfiltration (MF) process, without removal of the flocs produced via the coagulation pretreatment. The main issue explored was the effects of different coagulation conditions on the particle characteristics that would also significantly affect the performance of membranes when filtering coagulated humic-rich water. The size distribution and morphological properties of flocs formed through the coagulation of humic-rich water were characterized and the impact of Ca2+ on these characteristics that were associated with the performance of the MF membrane was also determined. Epi/DMA additions from 50% to 150% of the charge neutralization dose substantially decreased fouling compared to when filtering raw humic-rich water. Short-term fouling was increased when 1mM Ca2+ was added, but the charge neutralization coagulation removed almost all of the fouling tendency that had occurred when filtering Ca–humic solution. The median diameter and the fractal dimension of flocs produced were increased as the zeta potential reached close to zero, which resulted in the formation of a cake layer that was easily removed from the surface of the membrane.

Changing shapes and implied viscosities of suspended submicron particles

Abstract. The change in shape of atmospherically relevant organic particles is used to estimate the viscosity of the particle material without the need for removal from aerosol suspension. The dynamic shape factors χ of particles produced by α-pinene ozonolysis in a flow tube reactor, under conditions of particle coagulation, were measured while altering the relative humidity (RH) downstream of the flow tube. As relative humidity was increased, the results showed that χ could change from 1.27 to 1.02, corresponding to a transition from aspherical to nearly spherical shapes. The shape change could occur at elevated RH because the organic material had decreased viscosity and was therefore able to flow to form spherical shapes, as favored by the minimization of surface area. Numerical modeling was used to estimate the particle viscosity associated with this flow. Based on particle diameter and RH exposure time, the viscosity dropped from 10(8.7±2.0) to 10(7.0±2.0) Pa s (two sigma) for an increase in RH from < 5 to 58 % at 293 K. These results imply that the equilibration of the chemical composition of the particle phase with the gas phase can shift from hours at mid-range RH to days at low RH.

Effects of epichlorohydrin–dimethylamine on coagulation and membrane performance of ferric chloride in coagulation–ultrafiltration hybrid process

Cationic polymer epichlorohydrin–dimethylamine (DAM–ECH) was applied as coagulation aid of ferric chloride (FC) in treatment of humic acid–kaolin (HA–Kaolin) simulated water in this study. Impacts of DAM–ECH on coagulation performance, flocs characteristics and membrane fouling of FC in coagulation–ultrafiltration (C–UF) process were investigated under different pH conditions. Results showed that the removal rates of UV254 (ultraviolet adsorption at 254nm) and DOC (dissolved organic carbon) of FC/DAM–ECH was much better than that of FC at same dosage. The optimum coagulation condition was FC at 10mg/L with FC/DAM–ECH mass ratio (MR) of 3:1 based on the consideration of treatment cost and performance. Moreover, turbidity, UV254 and DOC removal rates increased when pH increased from 4 to 6 and then decreased as pH grew from 7 to 10. Thus, the optimum pH for coagulation was also determined to be 6 accordingly. Addition of DAM–ECH also increased sizes of produced flocs and made them looser in structure comparing with FC–HA flocs. Meanwhile, results obtained from ultrafiltration experiments showed that membrane fouling would be reduced by introducing DAM–ECH in coagulation treatment; the optimum membrane performance was given by FC/DAM–ECH under pH 6. In conclusion, proper dose of FC/DAM–ECH under pH 6 could ensure an ideal HA removal rate and meanwhile increase operating duration of C–UF system by restricting membrane fouling.

Improvement of Coagulation Process for the Prut River Water Treatment using Aluminum Sulphate

The aim of presented research was to optimize the treatment process of the Prut River water. In order to realize the proposed goal, there were studied the following factors which can improve the process of coagulation: (i) the infl uence of stirring speed during coagulation and (ii) the infl uence of the concentration of the coagulant solution added in the process of coagulation. The optimal conditions of coagulation were established using the Jar-test method. Application of the recommended procedure contribute to the reduction of the coagulant dose, the contact time, the aluminum concentration in water and the expenses for water treatment.

Know-how laboratory diagnosis of blood coagulation conditions

The lecture is devoted to the basic principles for laboratory diagnosis of blood coagulation as one including: 1) trained doctors; 2) demand equipment and methods appropriate to the profile and capacity of health facilities; 3) constructive solutions to issues of organizational and economic nature; 4) «Noli nocere» («do not harm») from the hospital management.

응집조건이 응집-UF 공정의 막오염에 미치는 영향

응집조건이 응집-UF 공정의 막오염에 미치는 영향

A Novel Approach to Synthesize Helix Wave Hollow Fiber Membranes for Separation Applications

Helix wave hollow fiber membranes are promising candidate to mitigate fouling and polarization effects in membrane operations. Current study describes a novel but simple approach to synthesize hollow fiber membranes with helix wave configuration. Poly(ether sulfone) (PES) based helix-waved hollow fiber membranes have been fabricated by dry-wet phase inversion process by using asymmetric coagulation conditions. Frequencies of the wave cycle have been observed approximately 20 and the wave length 7.1-7.6mm under the specifically required operating conditions defined by dope solution extrudate rate of 1g/min through 4cm of air-gap heights with 8.6m/min of winding speeds. On the other hand, simple hollow fibers are formed when the elongation force exerted by the winder is much higher than the surface tension of the external coagulant. The process can be useful for making polymer fibers for other applications as well.

Modifications of humoral factors, indicators of early postinfarction heart remodeling under influence of anticoagulant therapy in patients with Q-wave myocardial infarction

The role of humoral factors in the process of early postinfarction heart remodeling, left ventricle aneurism and thrombus formation in acute period of Q-wave myocardial infarction is an actual problem of modern cardiology. In order to investigate condition of coagulation and aggregation nexuses of hemostasis, matrix metalloproteinases and their inhibitor system, indexes of heart remodeling under influence of different anticoagulation agents, 97 patients with Q-wave myocardial infarction were examined. The treatment led to a decrease of matrix metalloproteinase concentration and an increase of tissue inhibitor of metalloproteinase-1 serum level, a decrease of blood serum procoagulant properties and activation of fibrinolytic processes, decrease of immune-inflammatory reactions and improvement of endothelial function.

Hybrid coagulation/membrane process treatment applied to the treatment of industrial dyeing effluent

A combined system of coagulation and membrane processes was investigated in this study for reactive dyeing wastewater treatment. Microfiltration (MF) and ultrafiltration (UF) membranes were tested in order to study the effect of the membrane type on the hybrid system performances. Additionally, membrane resistance analyses were conducted in order to understand the membrane fouling mechanism. Two different coagulants were used: Al2(SO4)3(Alum) and Amerfloc445. The influence of the coagulation conditions including coagulant nature and shear rate and duration on the UF behavior was studied. Indeed, a procedure of flocs breakage–reformation under different shear intensities was followed in the coagulation step, during these tests, flocs size and sensitivity to breakage as well as their regrowth ability were examined. The filtration results indicated that the coagulation step did not enhance the MF performances. The coagulation/ultrafiltration system was found to be better not only in term of permeate quality but also in fouling minimization. Although, Amerfloc445 generated the largest flocs with the best regrowth ability, but these flocs were more sensitive in increasing shear rate. As a result, the flocs breakage dropped the UF normalized flux by at least 22% with Amerfloc445 against a maximum of almost 12% with Alum. The extension of the shear duration from 5 min to 10 min affected the UF behavior especially in the presence of Amerfloc445; indeed the normalized flux decrease reached 14% against just 3% for pre-coagulated effluent with Alum.

Optimization of the Coagulation Process for Kaolin and Humic Acid Removal Using Polymeric Aluminum Ferric Sulfate

In the paper, the optimization of the coagulation process for Kaolin and humic acid removal using polymeric aluminum ferric sulfate (PAFS) was studied. In order to obtain the maximum turbidity and humic acid removal efficiency of Kaolin and humic acid simulated wastewater, the optimum coagulation conditions was investigated with the factors of mixing speed and time. Furthermore, mixing speed and time including parameters affecting the coagulation performance such as rapid mixing speed, rapid mixing time, slow mixing speed and slow mixing time using single factor and orthogonal array L9 (34) analysis were examined. The results showed that the optimum single factor of mixing speed and time indicated rapid mixing speed of 350 rpm, rapid mixing time of 1.0 min, slow mixing speed of 60 rpm and slow mixing time of 20 min. Then the orthogonal optimization experiment of mixing speed and time indicated maximum HA removal efficiency was 97.5% at rapid mixing speed of 350 rpm, rapid mixing time of 1.25 min, slow mixing speed of 60 rpm, and slow mixing time of 20 min.

Preparation of PVDF membranes via the low-temperature TIPS method with diluent mixtures: The role of coagulation conditions and cooling rate

To obtain a high-performance polyvinylidene fluoride (PVDF) membrane, low-temperature thermally induced phase separation (LT-TIPS) was employed to prepare microporous flat PVDF membranes and hollow-fiber membranes using diluent mixtures of triethylphosphate and diethylene glycol monoethyl ether acetate. The membrane morphology was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results show that thermally induced phase separation (TIPS) played a more important role than nonsolvent-induced phase separation (NIPS) in determining the cross-sectional morphology of the membranes, and the surface structure was mainly affected by NIPS in a low-temperature (0°C) coagulation bath. By increasing the temperature of the coagulation bath, different structures of membranes, such as spherulites and cellular and sponge structures, were observed. It is believed that the formation mechanism of these membranes depended on a combined NIPS and TIPS process. Wide-angle X-ray diffraction (XRD) analysis indicated that PVDF crystallized into an α-phase crystal structure for all the membranes tested. In addition, the porosity, tensile strength and filtration performance of the flat membranes were measured. On the basis of the above results, a hollow fiber membrane with highly interconnected pores and high porosity could be prepared employing LT-TIPS.

Coagulation behavior and floc structure characteristics of cationic lignin-based polymer-polyferric chloride dual-coagulants under different coagulation conditions

To recycle papermaking sludge, a novel lignin-based flocculant with high cationic degree and molecular weight was introduced.

Preparation and coagulation performance of solid aluminium formate

A simple method for the preparation of an aluminium formate coagulant in solid form was developed. Aluminium hydroxide and formic acid were used as starting materials. The effect of different ratios of the starting materials in the synthesis was investigated with a view to minimising the required amount of formic acid. The coagulation performance of the products obtained was evaluated in surface water treatment and aluminium sulphate was used as reference coagulant. Most of the prepared aluminium formates were found to be at least equally effective as aluminium sulphate at optimum coagulation conditions. It was found that relatively small amounts of formic acid are adequate to obtain a well-functioning product. Removal efficiencies of obtained aluminium formates were found to be dependent on coagulation condition, namely coagulant dose and pH. In most conditions, aluminium formate had a similar coagulation efficiency to that of aluminium sulphate. Especially at low pH range, higher removal efficiencies were obtained with aluminium formate than with aluminium sulphate, whereas around pH 5 with high dosages aluminium sulphate was more effective. The prepared aluminium formate coagulants are potential alternatives to commonly used coagulants, especially in applications where chloride and sulphate are problematic due to corrosion or formation of precipitates. The solid form of the coagulant offers some practical benefits over a similar liquid product.