Single Coagulation Research Articles

Characterization of coagulation behavior of titanium tetrachloride coagulant for high and low molecule weight natural organic matter removal: The effect of second dosing

A two-stage titanium tetrachloride (TiCl4) dosing strategy is applied for investigating the coagulation effect on simulated water containing humic acid (HA) and fulvic acid (FA) and these represent the dissolved organic matter (DOM). The influence of second TiCl4 dose on coagulation efficiency, flock re-growth and the fractal dimension properties is studied for the beneficial effect of the second coagulant dose. Moreover, the impact of increased shear on the ultra filtration permeate flux in coagulation–ultra filtration (C–UF) hybrid process is explored. A small second dose essentially decreases the residual turbidity and improves the organic matter removal. Also, flocks with larger size and better recoverability result and having more compact structure than those obtained without the second TiCl4 coagulant dose. At the same total TiCl4 coagulant concentrations, the two-stage dosing mode reveals significant advantage over the single coagulant dosing in terms of turbidity removal, flock size and recoverability although organic matter removal and flock compactness degree are more or less deteriorated during the two-stage dosing process. The second TiCl4 dose contributes to larger re-generated flocks with better re-growth ability than those obtained without the second dose within a wide range of high shear rate and even with prolonged breaking period. Two-stage dosing mode could improve the ultra filtration permeate flux under certain shear conditions. An extension in breakage time leads to much severer flux decline than short breakage periods. In case of FA simulated water, the ultra filtration permeate flux was less sensitive to increasing shear rate than in case of HA simulated water.

Lutein recovery from Chlorella sp. ESP-6 with coagulants

Production of algal lutein included cell cultivation, biomass harvesting, cell wall disruption, and subsequent purification if needed. This work cultivated Chlorella sp. ESP-6 cells in photobioreactor to a biomass content of 1.1 gl(-1) and then the freezing-grinding, ultrasonic treatment (20 and 42kHz) and microwave treatment were used to disrupt the cell walls for recover intracellular lutein. The grinding recovered more lutein than ultrasound or microwave pretreatment. Single coagulation using >30 mgl(-1) chitosan or dual-conditioning using 10 mg l(-1) polyaluminum chloride and 10 mgl(-1) chitosan effectively enhance sedimentation and membrane filtration efficiency of algal suspensions. However, the presence of coagulants lowers the lutein yield from algal biomass in the subsequent 20 kHz ultrasound treatment and purification process. Simulation results revealed affine adsorption of lutein onto chitosan molecules via hydroxyl-amine interaction. The possible drawback by pre-treatment stage should be considered together with the subsequent recovery stage in whole process assessment.

Coagulation optimization using ferric and aluminum salts for treating high algae and high alkalinity source water in a typical North-China plant

Coagulation optimization using coagulants of ferric chloride (FeCl3), polyaluminum chloride (PACl), and their combinations (FeCl3/PACl) were evaluated through jar tests, by treating source water with high algal content (10–40 million cells/L) and high alkalinity (80–110 mg/L). The results indicated that when compared to single coagulants, the combined coagulants showed a superior coagulation performance in terms of turbidity, UV254, and algal removal. The optimal dosage was determined as 30–35 mg/L by using the combined PACl/FeCl3 (1:2 by mass) and dosing PACl followed by FeCl3. By adding the coagulant aids of polymerized diallyl dimethyl ammonium chloride (HCA) and polyacrylamide (FO4190), the floc sizes may enlarge up to 1.75–2.0 mm. Scanning electron micrographs showed that the coagulant combination can form a more compact reticular aluminum-ferric structure, and thus increased the settleability of the flocs. The combined coagulation was further evaluated in full-scale water treatment plants, confirming the improvement of the removal of algae, turbidity, and residual iron in the treated water.

Reduction of organic matter and trihalomethane formation potential in reclaimed water from treated municipal wastewater by coagulation and adsorption

Advanced municipal wastewater treatment for reclamation, which can both relieve water shortage and decrease the impact of human activities on the environment, is drawing more and more attention all over the world. In this study, dissolved organic matter (DOM) removal efficiency and trihalomethane formation potential (THMFP) were compared in four treatment processes: coagulation, adsorption, coagulation subsequent adsorption (FeCl3–PAC) and adsorption subsequent coagulation (PAC–FeCl3). Distributions of trihalomethane specials in different treatment processes were also studied. The results indicated that FeCl3–PAC process was better for UV254 and DOC removal efficiency than single coagulation, single adsorption and PAC–FeCl3. And FeC13 achieved the highest coagulation removal efficiency of which up to 45.4% of UV254 and 43.3% of DOC at the dosage of 80mg/L, in comparison with PACl, PFC and Al2(SO4)3. Least THMs were found in FeCl3–PAC process compared with other three treatment processes. However, the special trihalomethane formation potential (STHMFP) of coagulation process was lower than other three treatment processes. Additionally, CHBr2Cl and CHBr3 were dominant species in THMs during wastewater chlorination process and accounted for 80% of the total THMs. It was different with that of surface water disinfection, in which CHCl3 was dominant species of the THMs.

General mechanisms of coagulation and targets of anticoagulants (Section I)

Contrary to previous models based on plasma, coagulation processes are currently believed to be mostly cell surface-based, including three overlapping phases: initiation, when tissue factor-expressing cells and microparticles are exposed to plasma; amplification, whereby small amounts of thrombin induce platelet activation and aggregation, and promote activation of factors (F)V, FVIII and FXI on platelet surfaces; and propagation, in which the Xase (tenase) and prothrombinase complexes are formed, producing a burst of thrombin and the cleavage of fibrinogen to fibrin. Thrombin exerts a number of additional biological actions, including platelet activation, amplification and self-inhibition of coagulation, clot stabilisation and anti-fibrinolysis, in processes occurring in the proximity of vessel injury, tightly regulated by a series of inhibitory mechanisms. "Classical" anticoagulants, including heparin and vitamin K antagonists, typically target multiple coagulation steps. A number of new anticoagulants, already developed or under development, target specific steps in the process, inhibiting a single coagulation factor or mimicking natural coagulation inhibitors.

The discovery of rivaroxaban: translating preclinical assessments into clinical practice.

Direct oral anticoagulants that target a single coagulation factor (such as factor Xa or thrombin) have been developed in recent years in an attempt to address some of the limitations of traditional anticoagulants. Rivaroxaban is an oral, direct factor Xa inhibitor that inhibits free and clot-bound factor Xa and factor Xa in the prothrombinase complex. Preclinical studies demonstrated a potent anticoagulant effect of rivaroxaban in plasma as well as the ability of this agent to prevent and treat venous and arterial thrombosis in animal models. These studies led to an extensive phase I clinical development program that investigated the pharmacological properties of rivaroxaban in humans. In these studies, rivaroxaban was shown to exhibit predictable pharmacokinetics and pharmacodynamics and to have no clinically relevant interactions with many commonly prescribed co-medications. The pharmacodynamic effects of rivaroxaban (for example, inhibition of factor Xa and prolongation of prothrombin time) were closely correlated with rivaroxaban concentrations in plasma. The encouraging findings from preclinical and early clinical studies were expanded upon in large, randomized phase III studies, which demonstrated the clinical efficacy and safety of rivaroxaban in a broad spectrum of patients. This article provides an overview of the discovery and development of rivaroxaban, describing the pharmacodynamic profile established in preclinical studies and the optimal translation to clinical studies in healthy subjects and patient populations.

Derivation of the non-inferiority margin for the evaluation of direct oral anticoagulants in the treatment of venous thromboembolism.

BackgroundDirect oral anticoagulants that target a single coagulation factor have been developed as an alternative to standard therapies with heparin and/or vitamin K antagonists. The purpose of this study was to derive non-inferiority margins suitable for randomised clinical studies designed to evaluate these agents for the treatment of venous thromboembolism (VTE).MethodsWe performed a systematic review to derive non-inferiority margins suitable for use in studies evaluating direct oral anticoagulants for the treatment of VTE. A PubMed search identified publications that evaluated current standard treatment versus placebo, ‘no treatment’ or ‘less intensive treatment’ in patients with symptomatic deep vein thrombosis (DVT) and/or pulmonary embolism (PE). Publications were eligible if they had a randomised study design, included patients with symptomatic DVT and/or PE, used objective diagnostic methods to document the index event and reported objectively confirmed symptomatic recurrent VTE.ResultsFourteen publications were included in the analysis. Recurrent VTE occurred in 25 (1.5%) out of 1715 patients who received current standard of care and in 157 (9.2%) out of 1711 patients who received placebo, ‘no treatment’ or ‘less intensive treatment’, for an odds ratio of 0.18 (95% confidence interval, 0.14−0.25; test for heterogeneity, p=0.87). In order to preserve 50% or 75% of the established treatment effect using a linear scale, the corresponding thresholds for non-inferiority equalled 2.50 and 1.75, respectively.ConclusionsThis systematic review and statistical approach determined non-inferiority margins suitable for use in studies of direct oral anticoagulants for the treatment of DVT and/or PE.

Age dependency of coagulation parameters during childhood and puberty

Use of age-adjusted reference values is crucial for correct diagnosis and management of thrombotic and hemorrhagic disease in children. They vary with utilized reagents and analyzers. We established reference values with the Sysmex CA-1500 System and in parallel with the Behring BCS System using reagents from Siemens Healthcare Diagnostics Products GmbH. After informed consent, blood samples were obtained from 218 healthy children and 52 healthy adults, grouped as 1-6 months (n = 29), 7-12 months (n = 25), 1-5 years (n = 57), 6-10 years (n = 57), 11-18 years (n = 50) and > 19 years (n = 52). Most coagulation parameters demonstrate good comparability between analyzers with the exception of PT and APTT. Single coagulation factors fibrinogen, factor (F) II, FIX, FXI and XII were significantly decreased in the youngest children; the strongest age dependency was found for coagulation inhibitors Protein C and S, both significantly decreased in infancy and young childhood. We confirmed that high levels of von Willebrand factor are found in the youngest children without increased levels of FVIII followed by decreased von Willebrand levels in the subsequent age group. In children with blood group O a less distinct increase in time was found, compared with individuals with one of the other blood groups. The correlation between the CA-1500 and the BCS system was remarkable. Differences were most pronounced between children < 12 months and older children and adults, confirming the phenomenon of developmental hemostasis. The rationale for age-related changes in the hemostatic system remains unraveled. Our results underline the need for age-specific reference ranges.

On the value of routine prothrombin time screening in elective neurosurgical procedures

The authors performed a study to evaluate whether preoperative assessment of prothrombin time (PT) is mandatory in patients undergoing routinely planned neurosurgical procedures. The charts of all patients admitted to general wards of the authors' department for routinely planned surgery (excluding trauma and ICU patients) between 2006 and 2010 were retrospectively reviewed. The authors assessed preoperative PT and the clinical courses of all patients, with special consideration for patients receiving coagulation factor substitution. All cases involving hemorrhagic complications were analyzed in detail with regard to pre- and postoperative PT abnormalities. Prothrombin time was expressed as the international normalized ratio, and values greater than 1.28 were regarded as elevated. Clinical courses and PT values of 4310 patients were reviewed. Of these, 33 patients (0.7%) suffered hemorrhagic complications requiring repeat surgery. Thirty-one patients (94%) had a normal PT before the initial operation, while 2 patients had slightly elevated PT values of 1.33 and 1.65, which were anticipated based on the patient's history. In the latter 2 cases, surgery was performed without prior correction of PT. Preoperatively, PT was elevated in 78 patients (1.8%). In 73 (93.6%) of the 78 patients, the PT elevation was expected and explained by each patient's medical history. In only 5 (0.1%) of 4310 patients did we find an unexpected PT elevation (mean 1.53, range 1.37-1.74). All 5 patients underwent surgery without complications, while 2 had received coagulation factor substitution preoperatively, as requested by the surgeon, because of an estimated risk of bleeding complications. None of the 5 patients received coagulation factor substitution postoperatively, and later detailed laboratory studies ruled out single coagulation factor deficiencies. There was no statistically significant association between preoperatively elevated PT levels and the occurrence of hemorrhagic complications (p = 0.12). Before the second procedure but not before the initial operation, 4 (12%) of the 33 patients had elevated PT. The findings suggest that the value of preoperative PT testing is limited in patients in whom a normal history can be ascertained. Close postoperative PT control is necessary in every neurosurgical patient, and better tests need to be developed to identify patients who are prone to hemorrhagic complications.

Características farmacodinámicas y farmacocinéticas. Mecanismo de acción de los nuevos anticoagulantes orales

Thromboembolic disease, both arterial and venous, is a major cause of morbidity and mortality in developed countries. The new anticoagulants exert their action by selective, direct and reversible inhibition of a single coagulation factor. Although the results of several phase III trials have demonstrated the safety and efficacy of these drugs, their mechanism of action, as well as the pharmacodynamics and pharmacokinetics of these drugs, need to be understood for their correct use. The present review discusses the features of the new anticoagulants whose clinical development is more advanced, both those designed to block active factor X, such as rivaroxaban or apixaban, and those designed to block thrombin (also active factor II): dabigatran.

Coagulation optimization for low temperature and low turbidity source water using combined coagulants: a case study

abstract Coagulation optimization using coagulants of ferric chloride (FeCl3), polymer–polyaluminum ferric chloride (PAFC) and their combinations (FeCl3/PAFC) was evaluated by performing jar tests for treating source water with low temperature (<10°C) and low turbidity (1.5–8 NTU) i,n a typical North-China water treatment plant (WTP), Tanggu WTP. The results indicated that compared to single coagulant, the combined coagulants showed superior coagulation performance in terms of turbidity, UV254, CODMn, iron, and aluminum removal. The optimal dosage was determined as 20 mg/L using the combined PAFC/FeCl3 (3:1 by mass) and dosing PAFC with a 5–20 s interval followed by FeCl3. Scanning electron micrographs further showed that the coagulations combination can form a more compact structure that increases the settleability of the flocculation flocs.

Plasma components: properties, differences, and uses

General use of plasma components includes replacement for multiple coagulation factor deficiencies, for treatment of single coagulation factor deficiencies for which a concentrate is unavailable, and as a replacement fluid used in therapeutic plasma exchange for thrombotic thrombocytopenic purpura. Four major products currently transfused are fresh-frozen plasma (FFP), plasma frozen within 24 hours of phlebotomy (FP24), cryoprecipitate-poor plasma (CPP), and thawed plasma. FP24, CPP, and thawed plasma contain decreased amounts of labile coagulation factors. Pathogen reduction technology has included solvent/detergent, methylene blue, and ultraviolet light irradiation with psoralen or riboflavin treatment and is available in Europe but not in the United States. Pathogen-reduced plasma may contain reduced levels of certain coagulant and/or anticoagulant factors compared to FFP. Clinical findings with pathogen-reduced plasma have provided an impetus to the US Food and Drug Administration to promulgate specific requirements for approval of novel plasma products, some of which may be too burdensome for the industry to readily overcome.

Recommendations for the usage and treatment with fresh frozen plasma

Fresh frozen plasma (FFP) is a blood component obtained from processed whole blood or collected by plasmapheresis and afterwards stored in frozen state. Indications for the clinical use of FFP are single coagulation factor deficiencies (such as F V and F XI), multiple coagulation factors deficiency (most frequent as a consequence of massive hemorrhage), coagulopathy caused by advanced liver disease, warfarin mediated coagulopathy and thrombotic thrombocytopenic purpura. Standard FFP treatment dose in mentioned indications is generally 10–20 ml/kg of patient body weight. During the treatment attention should be paid to possible FFP treatment related adverse effects. Most frequent are allergic reactions. We should not consider FFP as a treatment approach in clinical situations where equally effective and safer treatment modalities are available.

Coagulation and UF treatment of pulp and paper mill wastewater in comparison

Abstract A study using coagulation-flocculation and ultrafiltration (UF)methods for pulp and paper mills’ wastewater (WW)was carried out. The reduction efficiencies of turbidity and chemical oxygen demand (COD), the removal efficiency of total suspended solids (TSS) and absorbance at 254 nm were the main evaluating parameters. Using coagulation-flocculation, the efficiencies of alum and polyaluminum chloride (PACl)were studied, when used alone and when coupled with flocculant aids. During the coagulation-flocculation process, use of a single coagulant, the coagulant dosage, and the pH, play an important role in determining the coagulation efficiency. At the optimum PACl dosage of 840 mg L−1 and optimum pH of 9.0, turbidity reduction was found to be 94.5%. A combination of inorganic coagulant and flocculant, or polymer was applied, in which PACl was used coupled with the polyelectrolytes Organopol WPB20 and WPB40. PACl coupled with Organopol WPB20 by optimal pH 9 gave a 98.3% reduction of turbidity, 91.9% removal of TSS, and a 60.2% reduction in COD. Ultrafiltration trials were carried out on a pilot scale. A tubular module was used with ceramic membrane. This membrane is a multi-channel membrane with an active surface layer made of Al2O3 and ZrO2. Within the acidic range, the turbidity and TSS were removed at above 99%.

Proteine mit Einfluss auf die Blutgerinnung

This review describes some natural proteins, which can be employed, either as factor concentrates derived from human plasma or as recombinant drug, to modulate the coagulation system. I will address some biochemical characteristics and the physiological role of von Willebrand factor, the coagulation factors of the extrinsic and intrinsic pathways, and the physiological anticoagulant protein C. In addition, I will detail the pharmacological compounds, which are available for influencing or substituting the coagulation proteins: desmopressin (DDAVP), single coagulation factor concentrates, prothrombin complex concentrates, and protein C concentrate. In particular, I will address some treatment topics of general medical interest, such as the treatment of massive bleeding, the correction of the coagulopathy induced by vitamin K-antagonists in patients with cerebral haemorrhage, and of the coagulopathy of meningococcemia. Finally, I will describe some properties and practical clinical applications of the recombinant anticoagulans lepirudin and bivalirudin, which are derived from hirudin, the natural anticoagulant of the medical leech.

Effect of suspended solids in secondary wastewater effluent on DOC removal by enhanced coagulation

Wastewater recycling is increasingly seen as a sustainable solution to meet the increasing water demand. However, organic matters and suspended solids (SS) affects its treatment, distribution and use in many different ways, including fouling of membrane when membrane process is adopted. Enhanced coagulation can effectively remove both SS and organic matters, consequently increasing the performance of membrane. However, it is still unknown how dissolved organic carbon (DOC) removal is affected by the presence of SS, especially when microbes and bio-molecules are present in the effluent. Thus, this study aims to investigate the impact of SS on DOC removal by enhanced coagulation (with ferric chloride), from secondary wastewater effluent (SWWE). Results indicated two-stage DOC removal for a single coagulation pH over lower and higher doses of coagulant. In the first stage, DOC removal was compromised when SS was present at concentrations as low as 8.8 mg/L, suggesting removal of SS prior to coagulation is important for effective DOC removal and sludge reduction.

The procoagulant effects of fine particulate matter in vivo

Inhalation of fine particulate matter (<2.5 μm; fine PM) has been shown to increase the risk for cardiovascular events. In this letter, we reappraise the role of tissue factor (TF) antigen and we also summarize changes in measured coagulation proteins in humans and rodents by other studies with fine PM. By considering all studies including ours, we conclude that monitoring the overall coagulation state by measuring capacity assays such as thrombin generation, and quantification of TF activity would be more suitable than determining single coagulation proteins (such as TF antigen) in order to better assess the systemic prothrombotic effects of fine PM.

Advanced Treatment of Coking Wastewater by Coagulation with PAC

An integrated technique was investigated, aiming to provide an effective method for the treatment of biologically treated coking wastewater and to reduce pollutants to concentration values below the limits imposed by the legislation. Coking wastewater containing 270 mg/L COD and 202 times color was treated by coagulation using PAC as well as PAC +PAM, respectively. The application of coagulation using PAC+PAM resulted to a much more efficient removal of color, COD and SS in comparison with single coagulation without PAC. The optimal condition for coagulation with PAC was pH 8, dosage 75 mg/L and dynamic condition 1-minute high speed stirring followed by 15-minute low speed stirring. The optimal condition for coagulation with PAC and PAM was: PAM dosage of 6 mg/L, PAC dosage of 70 mg/L, pH of 8 and reaction time of 20 minutes. Both processes of coagulation were found to be efficient for removal of COD from coking wastewater, but ineffective in reducing color.

Coagulation and advanced oxidation processes in the treatment of olive mill wastewater (OMW)

This paper proposes the use of a combination of two treatment processes for the removal of organic pollutants from the olive oil mill wastewater (OMW). The two treatment processes are, a single coagulation stage followed by a single advanced oxidation, AOP, stage. For the AOPs, the following processes were used; UV, O3, O3/UV and H2O2/UV depending on the operating time. Two coagulant Al3+ and Fe3+ ions were used in the experimental program conducted in this study. The concentration of the chemical oxygen demand (COD) was measured in the effluent of the treated wastewater for each experiment. The percent removal of the COD concentration achieved using the two coagulant Al3+ and Fe3+ ions at pH = 9, was 54% and 58%, respectively. In a comparison, the percent removal of the COD is found in the range of 10–39% using an advanced oxidation process alone. The percent removal of the COD concentration achieved using the combined processes, coagulation and AOPs (O3, O3/UV and H2O2/UV), are 90%, 95% and 94%, respect...

New Anticoagulants for the Prevention of Thromboembolism

The traditional agents used for thromboprophylaxis are effective and safe but have limitations particularly related to ease of administration. Newer agents targeting single coagulation factors such as the direct thrombin inhibitor dabigatran and the factor Xa inhibitors rivaroxaban and apixaban have demonstrated efficacy and safety for thromboembolism prophylaxis in the orthopedic population and have the additional benefit of oral administration and predictable pharmacokinetics. Pharmacology of the new anticoagulants and published data on the use of these agents in total knee and hip replacement patients will be reviewed in this article.