Two-stage Coagulation Research Articles

Treatment of the railway freight wagon wash effluents by coagulation methods on accelator reactor

This paper presents results of the research carried out on a system made to pretreat the effluents produced in water treatment of dirty surfaces of railway transportation means (RTMs) mainly G, H, T and incidental F classes of rolling stock according to the International Union of Railways (IURs). The installation was designed for coagulation–flocculation pretreatment of wastewater with flow accelator reactor (AR) in total amount of up to 75.0 m3 day−1. The raw wastewater (RW) was characterized by a significant diversity of loads: TSS (total suspended solids), TDS (total dissolved solids), COD & BOD5 (chemical & biochemical oxygen demand) and periodically it had extremely different colors, Ta (turbidity) and EE (etheric extract). The application of two-stage, coupled acid-alkali or alkaline-acid coagulation using aluminum coagulants with final flocculation and phase separation in the system implemented in practice to treat the wastewater of statistically typical composition, usually allowed to removal, accordingly: EE & TSS > 99% and to eliminate completely color and Ta. However, COD and BOD5 were removal at different levels, depending on both initial concentrations and chemical composition of load pools registered in the RW, and a type of coagulation used. The use of pre-oxidation with aqueous solutions of hydrogen peroxide or peracetic acid coupled with coagulation based only on aluminum coagulants helps to achieve equal levels of removal of the basic indicator values and a sanitary clean stream of pretreated wastewater (PW) with a colony forming unit (CFU) of <100 ml−1.

Optimization studies for water defluoridation with two-stage coagulation processes using new industrial-based chemical coagulants

The fluoride removal capability of a new industrial-based chemical coagulant (Formula A) in one- and two-stage coagulation treatments was investigated in present study. Three main controlling factors, the coagulant concentration, reaction time and the initial pH of Formula A were studied on the fluoride removal accordingly, with the aid of other coagulants: Ecogent F-Loc, potassium ferrate (K2FeO4), and sodium aluminate (NaAlO2). Response surface methodology (RSM) was adopted to analyse the controlling factors on the fluoride removal efficiency (R%) using Box-Behnken designs (BBD). The coagulant concentration of Formula A shows the most significant effect on R% and better fluoride removal capability at an initial pH 12. Nevertheless, the R% has been shown to be independent of reaction time. Response optimisation revealed the highest R% (70.12%) can be achieved at 1000 ppm, 10 min of reaction time and initial pH of 2. Furthermore, K2FeO4 has a better R% in low pH regions of 2 to 4. Additionally, K2FeO4 achieved the highest R% (84%) at 1190 ppm and pH 9 with 8.5 min of reaction time. In a single coagulation stage, the use of Formula A or K2FeO4 are not able to meet Environmental Quality (Industrial Effluent) Regulations 2009 with discharge Standard B as specified by Department of Environment Malaysia, while a two-stage coagulation process can meet Standard A. Specifically, the combined formulation of using Ecogent F-Loc(1)- Formula A(2) and NaAlO2(1)- Formula A(2) were able to achieve treated water with less than 2 ppm fluoride. Moreover, recycling treated water also plays a major role in helping industries meet the strict treatment standards.

Two-stage coagulation process for enhanced oil removal from coal chemical wastewater

As a common pretreatment process for coal chemical wastewater, the conventional one-stage coagulation process has the problem of poor removal of small size oil, which will inhibit the subsequent biological treatment. Measures to improve oil removal efficiency based on the development of new coagulants and the addition of composite processes are common in the literature, but two-stage coagulation to improve coagulation efficiency has not been reported to date. Here, we optimized coagulation parameters and compared the oil removal efficiency of two-stage coagulation and one-stage coagulation. Under the same total dosage of coagulant (PAC), the optimum removal of oil in two-stage coagulation was achieved 90% which increased by 11% compared to one-stage process. P10 and P 1 μm were proposed to evaluate the oil removing effect of two-stage coagulation. In addition, SEM scanning was used to conduct flocs analysis and two-stage coagulation process simulation, revealing the principle of the excellent oil removal performance of two-stage coagulation. Finally, coagulant in filter residue was recovered by acidification method and the recovered coagulant was used again in the two-stage coagulation process of coal chemical wastewater. These results suggest that two-stage coagulation is a cost-effective alternative oil removal technique with high energy efficiency and environmental benign. This research may offer helpful insights to develop an advanced oil removal process.

Effect of Additives on Hydrophobicity of PVDF Membrane in Two-stage Coagulation Baths for Desalination

Effect of Additives on Hydrophobicity of PVDF Membrane in Two-stage Coagulation Baths for Desalination

Enhanced total phosphorus removal using a novel membrane bioreactor by sequentially alternating the inflow and by applying a two-stage coagulation control based on pre-coagulation

A membrane bioreactor by sequentially alternating the inflow and by applying a two-stage coagulation control based on pre-coagulation was evaluated in terms of phosphorus removal efficiency and cost-savings. The MBR consisted of two identical alternative reaction tanks, followed by aerobic, anoxic a...

Integrated Ultrafiltration Membranes and Chemical Coagulation for Treatment of Baker’s Yeast Wastewater

An integrated system ultrafiltration membrane-coagulation has been employed for removal of chemical oxygen demand (COD) and turbidity from baker's yeast effluents. Fouling in the membrane is a common problem; chemical coagulation has been used as a pre-treatment method to mitigate fouling. Poly aluminum chloride (PACl), aluminum sulfate and lime had been used as coagulants. The results indicated that PACl exhibited higher removal efficiency than other coagulants. Two-stage coagulation and combination of coagulants were also investigated. The removal efficiency of COD and turbidity were achieved 68% and 81% by two-stage coagulation by PACl-lime, respectively. The effects of operating conditions on the ultrafiltration process for two types of hollow fiber membranes polyvinylidene fluoride (PVDF) and polypropylene (PP) on permeate flow rate, turbidity and COD removal of wastewater were further investigated. The results showed that by increasing the feed pressure, flow rate and feed temperature the permeate flow rate increased and the removal efficiency decreased. Under optimum conditions, PVDF membrane showed higher performance but compromised the flux compared to PP membrane.

Removal Natural Organic Matter (NOM) in Peat Water from Wetland Area by Coagulation-Ultrafiltration Hybrid Process with Pretreatment Two-Stage Coagulation

&lt;p&gt;The primary problem encountered in the application of membrane technology was membrane fouling. During this time, hybrid process by coagulation-ultrafiltration in drinking water treatment that has been conducted by some research, using by one-stage coagulation. The goal of this research was to investigate the effect of two-stage coagulation as a pretreatment towards performance of the coagulation-ultrafiltration hybrid process for removal NOM in the peat water. Coagulation process, either with the one-stage or two-stage coagulation was very good in removing charge hydrophilic fraction, i.e. more than 98%. NOM fractions of the peat water, from the most easily removed by the two-stage coagulation and one-stage coagulation process was charged hydrophilic&amp;gt;strongly hydrophobic&amp;gt;weakly hydrophobic&amp;gt;neutral hydrophilic. The two-stage coagulation process could removed UV&lt;sub&gt;254&lt;/sub&gt; and colors with a little better than the one-stage coagulation at the optimum coagulant dose. Neutral hydrophilic fraction of peat water NOM was the most influential fraction of UF membrane fouling. The two-stage coagulation process better in removing the neutral hidrophilic fraction, while removing of the charged hydrophilic, strongly hydrophobic and weakly hydrophobic similar to the one-stage coagulation. Hybrid process by pretreatment with two-stage coagulation, beside can increased removal efficiency of UV&lt;sub&gt;254&lt;/sub&gt; and color, also can reduced fouling rate of the ultrafiltration membraneIt must not exceed 250 words, contains a brief summary of the text, covering the whole manuscript without being too elaborate on every section. Avoid any abbreviation, unless it is a common knowledge or has been previously stated.&lt;/p&gt;

One-stage vs. chromogenic assays in haemophilia A.

Haemophilia A severity is closely correlated to the factor VIII (FVIII) activity, which can be measured in different ways. The original one-stage clotting assay is still the most widely used. The two-stage coagulation assay eliminated many of the drawbacks of the one-stage assay and was further developed into the chromogenic assay, a two-staged test with purified coagulation factors in the first stage, and a FXa-specific chromogenic substrate in the second stage. In many patients with mild or moderate haemophilia A, there is a discrepancy between the one-stage and the two-stage assays. If only the one-stage assay is used, some patients will have normal FVIII levels and not be diagnosed as having haemophilia or be considered to have a milder bleeding risk than is the case. Other patients who have normal FVIII activity will be diagnosed as haemophilia A. All haemophilia treatment centre laboratories should have access to both one-stage and chromogenic FVIII:C assays. Appropriate standards should be employed to enable accurate FVIII:C measurement. Different assays to measure inhibitor activity to infused FVIII have been developed since 1959. Inhibitor results based on the one-stage or chromogenic FVIII:C assays are well correlated, but the one-stage assay may be influenced by nonspecific inhibition.

Assay discrepancy in mild haemophilia A.

There are three main methods used to assay factor VIII (FVIII) activity: the one-stage and two-stage clotting assays and the two-stage chromogenic method. The most commonly used assay for the diagnosis of haemophilia A is the automated one-stage FVIII assay. The classical two-stage FVIII assays are less frequently used. The chromogenic FVIII:C assay is a variant of the two-stage assay. It is easier to use and therefore used more commonly. Recently significant assay discrepancy has been recognised in the FVIII:C measurements in approximately one-third of mild haemophilia A patients. This so-called discrepant mild haemophilia A is characterised by a high ratio of one-stage/two-stage assay with one-stage FVIII levels that are typically more than double those of the two-stage coagulation assay. There are several mutations that destabilise the FVIIIa structure that can explain this result of a more pronounced decrease of the chromogenic FVIII:C activity compared with the one-stage activity. These mutations are clustered at the interfaces of the A1, A2 and A3 domains of the FVIII protein. The inverse discrepancy, where the one-stage assay gives lower FVIII:C results than the chromogenic assay, seems to be associated with mutations found close to important sites for thrombin cleavage or FIX binding. We are carrying out a study of mild haemophilia A samples from the Malmö Haemophilia Centre of families with a unique F8 genotype. The activity of FVIII will be measured using a chromogenic assay and two different one-stage assays. We hope to estimate the true size of assay discrepancy. This project will review assay discrepancy in mild/moderate haemophilia A and the risk of misdiagnosis. The overall aim is to estimate the size of the problem and to learn from the literature and experiences from our centre as well as to suggest recommendations on how to avoid misdiagnosis.

Research on physico-chemical pretreatment of wastewater from the production of wood coating materials

Abstract This paper presents the results of the research conducted on the installation designed for physico-chemical pretreatment of technological wastewater in the volume of up to 5.0 m3/day discharged from the production of protective and decorative coating materials used for wooden surfaces. The subject-matter installation constructed on a mobile pallet, consisted of a storage-averaging tank where concentrations were equalised with the use of circulation aeration and mixing. A variant, preliminary pre-oxidation with the use of hydrogen peroxide was conducted in this tank. A substantial installation set for the wastewater treatment plant consisted of two preliminary tube reactors, one cylindrical-conical processing reactor, stations for preparing and dispensing reagents and the sediment dewatering station. Considerable reductions in main chemical indicators of water pollution were obtained in the installation: both total suspended solids (TSS) and ether extract (EE) - more than 98%, chemical oxygen demand (COD) - 46-54%, biochemical oxygen demand (BOD5) - 39-46%, and free formaldehyde (HCHO) - 14-27% due to the use of pre-oxidation and the acid - alkaine double coagulation by applying the ALCAT 105 - SAX 25 system. The use of pre-oxidation with hydrogen peroxide in doses 250.0-450.0 mg/l and then two-stage coagulation resulted in an increase in the reduction of: COD and BOD5 by ca 10-15%, and HCHO by ca 58-66% with reference to the water pretreatment without pre-oxidation. The assessment of sediments formed during the process of pretreatment was made determining the leachable forms of metals (Cu, Ni and Ti) according to methodology of TCLP in compliance with the US EPA Method 1311.

Hydrophobic PVDF membrane via two-stage soft coagulation bath system for Membrane Gas Absorption of CO2

Hydrophobic PVDF membranes have been prepared through a two-stage/dual soft coagulation bath system. The prepared membranes exhibited improved hydrophobicity properties, where the contact angle values were increased, with higher efficiency of CO2 removal. Membrane prepared with two-stage coagulation bath system of 100wt.% ethanol and 80wt.% of NMP in water bath exhibited high water contact angle of 127°, high porosity of approximately 89% with small and narrower pore distribution. The membranes were tested in Membrane Gas Absorption (MGA) system with recorded CO2 removal efficiency of 85% for 3h and lasted for about 10 straight hours with higher flux and 65% efficiency of CO2 removal. The modified membranes have been characterized by contact angle, microstructure, maximum pore size (PRmax) and its distribution, surface roughness, membrane porosity and performances in MGA system. By increasing the polymer concentration, the morphology of the prepared membranes is improved due to the smaller pore characteristics and porous structure formed. The macrovoid structures severely formed in membrane with higher thickness which caused the low porosity and contact angle of the membrane.

Water Coagulation Using Electrostatic Patch Coagulation (EPC) Mechanism

Coagulation of fine particles to form large flocs is an essential step to reach efficient dewatering of wet materials. The electrostatic patch coagulation (EPC) mechanism was applied in this study to remove turbidity and natural organic matters in water using four different dosing-mixing schemes. Sufficient rapid mixing and slow mixing or applying two-stage coagulation benefit removal of turbidity. The EPC mechanism could only efficiently remove organic matters of molecular weight of 7500–10,000 Da. Only sufficient rapid mixing is relevant to organic matter removal. The mechanisms for natural organic matters (NOM) removal are proposed to be complexation of ions and NOM to form insoluble aggregates to be separated by membrane filtration.

Pre-Treatment of Natural Organic Matters Containing Raw Water using Coagulation

Coagulation is a commonly adopted process as a pretreatment step for minimizing membrane fouling. Three coagulants, polyaluminum chloride (PACl), alum, and FeCl3 were tested under four mixing-settling schemes for turbidity and natural organic matters (NOM) removal. The organic matters in the raw waters were fractionated by high performance size exclusion chromatography (HP-SEC) system and were characterized using the excitation-emission matrix (EEM) fluorescence spectra. Sufficient rapid mixing and slow mixing or applying two-stage coagulation benefit turbidity removal using PACl or FeCl3 under “electrostatic patch coagulation” (EPC) mechanism. The EPC mechanism is not efficient for alum coagulation. At higher coagulant doses, the NOM removal is not affected by mixing condition. Intensive rapid mixing alone benefits NOM removal using PACl or FeCl3. Alum is a poor coagulant for NOM removal under EPC mechanism.

Evaluation of three automated chromogenic FVIII kits for the diagnosis of mild discrepant haemophilia A

In some mild haemophilia A patients (discrepant phenotype), coagulation FVIII levels by one-stage assay (FVIII-1st) are more than double those by classical two-stage coagulation assay (FVIII-2st), and may fall within the normal range. Our aim was to assess automated two-stage chromogenic FVIII assays (FVIII-chr) for diagnosis of mild discrepant haemophilia A. Three chromogenic FVIII kits (Biophen, Coamatic and Dade-Behring) were evaluated, using recommended and extended incubation times. Samples were tested from patients with discrepant haemophilia (n = 7) and equivalent mild haemophilia (agreement between FVIII-1st and FVIII-2st, n = 4). For equivalent haemophilia, FVIII-chr were consistent with FVIII-1st and FVIII-2st for all kits at all incubation times. For discrepant haemophilia, using recommended incubation times, mean FVIII-chr using Biophen reagents was 22 IU/dl (range 13-31), with Coamatic 26 (17-34) and with Dade-Behring 41 (33-47), compared with 36 (27-44) for FVIII-1st and 8 (6-9) for FVIII-2st. FVIII-chr decreased as incubation time was increased with Biophen and Coamatic, but decreased less with Dade-Behring. FVIII-chr using the Dade-Behring kit gave similar results to FVIII-1st and is not suitable for diagnosis of mild discrepant haemophilia A. FVIII-chr by Biophen and Coamatic kits is suitable for diagnosis of these patients, especially with an extended incubation time.

Effects of Coagulation Conditions on Properties of Multifilament Fibers Based on Dissolution of Cellulose in NaOH/Urea Aqueous Solution

Effects of coagulation temperature, coagulants, and wet-spinning methods on structure and properties of novel regenerated cellulose (RC) fibers prepared from cellulose in 7.5 wt % NaOH/11 wt % urea aqueous solution on pilot scale spinning machine by one- and two-stage coagulation were investigated by tensile testing, optical microscopy, scanning electron micrograph, and wide-angle X-ray diffraction. The results indicated that H2SO4/Na2SO4 and H2SO4 aqueous solutions are potential coagulants for NaOH/urea system and fibers wet-spun from the two-stage coagulation obviously exhibited the better mechanical properties than those from the one-stage coagulation. The optimal coagulation conditions for two-stage coagulation are 10 wt % H2SO4/15 wt % Na2SO4 for the first coagulation bath and 5 wt % H2SO4 for the second bath or 5 wt % H2SO4/15 wt % Na2SO4 for the first coagulation bath and 10 wt % H2SO4 for the second bath. Moreover, the tensile strength of novel fibers increased with a drop in coagulation temperature. The diffusion rate between the coagulant and solvent plays a major role in determining the mechanical properties of the cellulose fibers. Our spinning process was quite different from that of the viscose process, in which orientation and coagulation proceed more or less simultaneously. The production method of this fiber wet-spun could be suitable in the wide range of coagulation conditions, compared to the viscose one.

A review on UV/TiO2 photocatalytic oxidation process (Journal Review)

Advanced oxidation processes (AOPs) with UV irradiation and photocatalyst titanium dioxide (TiO2) are gaining growing acceptance as an effective wastewater treatment method. A comprehensive review of the UV-TiO2 photocatalytic oxidation process was conducted with an insight into the mechanism involved, catalyst TiO2, irradiation sources, types of reactors, comparison between effective modes of TiO2 application as immobilized on surface or as suspension, and photocatalytic hybrid membrane system. Photocatalytic degradation technique with titanium dioxide is generally applied for treating wastewater containing organic contaminants due to its ability to achieve complete mineralization of the organic contaminants under mild conditions such as ambient temperature and ambient pressure. Recently, photocatalysis studies using TiO2 have been gaining attention for the degradation of persistent organic pollutants and other organic chemicals which are known to be endocrine disruptors. Treatment of wastewater in a titanium dioxide-suspended slurry reactor has been widely utilized due to its simplicity and enhanced degradation efficiency. However, this system requires separation of TiO2 from water after the photocatalytic process. The final section of the manuscript focuses on the removal of TiO2 using a membrane hybrid system. A two-stage coagulation and sedimentation process coupled with microfiltration hollow-fibre membrane process was found to achieve complete removal of TiO2, and the recovered TiO2 can be reused for a photocatalytic process after regeneration.

Specific Occlusion of Murine and Human Tumor Vasculature by VCAM-1–Targeted Recombinant Fusion Proteins

The tumor vasculature is increasingly recognized as a target for cancer therapy. We developed and evaluated recombinant fusion proteins targeting the coagulation-inducing protein soluble tissue factor (sTF) to the luminal tumor endothelial antigen vascular cell adhesion molecule 1 (VCAM-1, CD106). We generated fusion proteins consisting of sTF fused to antibody fragments directed against mouse or human VCAM-1 and characterized them in vitro by flow cytometry, surface plasmon resonance, and two-stage coagulation assays. Their therapeutic effects were tested in three human xenograft tumor models: L540rec Hodgkin lymphoma, Colo677 small-cell lung carcinoma, and Colo677/HDMEC small-cell lung carcinoma with human vasculature. Toxicity was analyzed by histologic examination of organs and determination of laboratory blood parameters. The fusion proteins bound VCAM-1 with nanomolar affinities and had the same coagulation activity as an sTF standard. Xenograft tumor-bearing mice treated with fusion protein (FP) alone or in combination with lipopolysaccharide (FP/L) or doxorubicin (FP/D) exhibited tumor-selective necrosis (L540rec tumors: 74% tumor necrosis [95% confidence interval {CI} = 55% to 93%] with FP/L versus 13% tumor necrosis [95% CI = 4% to 22%] with vehicle; Colo677 tumors: 26% [95% CI = 16% to 36%] with FP versus 8% [95% CI = 2% to 14%] with vehicle); tumor growth delay (Colo677/HDMEC: mean tumor weights after 3 days = 42 mg in FP-treated mice versus 71 mg in vehicle-treated mice, difference = 29 mg, 95% CI = 8 to 100, Mann-Whitney P = .008); and some tumor regressions (one of seven FP-treated Colo677 tumor-bearing mice and two of seven FP/D-treated mice). The fusion protein was well tolerated. Recombinant tissue factor-based fusion proteins directed against an intraluminal tumor endothelial cell marker induce tumor-selective intravascular coagulation, tumor tissue necrosis, and tumor growth delay.

Optimizing Water Treatment with Two-Stage Coagulation

Drinking water utilities are facing increasing regulatory pressure to optimize treatment processes, particularly the filtration process that is relied on as a physical barrier to pathogen contamination. In the presence of high concentrations of natural organic matter, traditional coagulation processes can be inadequate to meet these future standards. In this study, a natural water with a high total organic carbon concentration (>6 mg/L) was used to compare one- and two-stage alum coagulation processes. The two-stage coagulation process involved the application of alum at two locations separated by approximately 60 s of detention time. Bench-scale experiments were conducted with various water quality conditions and verified at the pilot scale. The settled-water turbidity was 25% less using the two-stage process, and the steady-state filter effluent particle counts for the two-stage process were approximately 50% lower than for the single-stage process. More importantly, the two-stage process did not exhibi...

The Two-Stage Coagulation of Milk Proteins in the Minimum of the Heat Coagulation Time-pH Profile of Milk: Effect of Casein Micelle Size

Milks with casein micelles larger or smaller than control milk were prepared by differential centrifugation. The heat stability of these modified milks increased markedly throughout the pH range 6.4 to 7.1 with decreasing casein micelle size. Within the region of the minimum in the heat coagulation time-pH profile, the control milk coagulated by a two-stage process, but the modified milks, because of their narrower casein micelle size distribution, coagulated by a single-stage process at the pH of minimum stability. The content of κ-CN and protein hydration increased as the size of the casein micelles decreased, and the level of glycosylation of κ-CN and protein surface hydrophobicity increased as a function of micelle size. The effect of casein micelle size on the heat stability of milk is likely to be related to changes in the above physico-chemical properties.

Pretreatment and biodegradability enhancement of DSD acid manufacturing wastewater

Two advanced oxidation processes, Fenton's reagent oxidation and ozonation, were used for pretreatment of a 4,4′-diaminostilbene-2,2′-disulfonic acid (DSD-acid) manufacturing wastewater on a laboratory scale. The results showed that both methods are suitable for partial removal of chemical oxygen demand (COD) and color as well as the enhancement of biodegradability of DSD-acid manufacturing wastewater before the conventional biological treatment. Fenton's reagent oxidation by 9.0 g/L H 2O 2 and 150 mg/L Fe 2+ and ozonation by 7.5 g/L O 3 led to an improved biodegradability (BOD 5/COD = 0.3). Fenton's reagent oxidation in combination with Fe 3+ coagulation has shown to effectively remove COD and color. About 90% of COD and 95% of color removals were obtained at the optimum condition, oxidation by 150 mg/L Fe 2+ and 2 g/L H 2O 2, followed by two-stage coagulation with 5 g/L and 2 g/L FeCl 3, respectively.