Conventional Coagulation Process Research Articles

The coagulation process for enveloped and non-enveloped virus removal in turbid water: Removal efficiencies, mechanisms and its application to SARS-CoV-2 Omicron BA.2

The coagulation process has a high potential as a treatment method that can handle pathogenic viruses including emerging enveloped viruses in drinking water treatment process which can lower infection risk through drinking water consumption. In this study, a surrogate enveloped virus, bacteriophage Փ6, and surrogate non-enveloped viruses, including bacteriophage MS-2, T4, ՓX174, were used to evaluate removal efficiencies and mechanisms by the conventional coagulation process with alum, poly‑aluminum chloride, and ferric chloride at pH 5, 7, and 9 in turbid water. Also, treatability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a recent virus of global concern by coagulation was evaluated as SARS-CoV-2 can presence in drinking water sources. It was observed that an increase in the coagulant dose enhanced the removal efficiency of turbidity and viruses, and the condition that provided the highest removal efficiency of enveloped and non-enveloped viruses was 50 mg/L of coagulants at pH 5. In addition, the coagulation process was more effective for enveloped virus removal than for the non-enveloped viruses, and it demonstrated reduction of SARS-CoV-2 Omicron BA.2 over 0.83-log with alum. According to culture- and molecular-based assays (qPCR and CDDP-qPCR), the virus removal mechanisms were floc adsorption and coagulant inactivation. Through inactivation with coagulants, coagulants caused capsid destruction, followed by genome damage in non-enveloped viruses; however, damage to a lipid envelope is suggested to contribute to a great extend for enveloped virus inactivation. We demonstrated that conventional coagulation is a promising method for controlling emerging and re-emerging viruses in drinking water.

Significance of ozonation on surfactant-polymer flooding produced water coagulation: Water quality deterioration inhibition, high-standard reinjection and mechanism

Surfactants and polymers are extensively being used to enhance oil recovery resulting in the generation of surfactant-polymer (SP) flooding produced water, which is more challenging to treat for reinjection compared with conventional produced water. Aiming at high-standard SP flooding produced water reinjection, this study investigated the coagulation-based treatment processes for the treatment of SP flooding produced water. The conventional coagulation process with two typical coagulants, poly-aluminum chloride (PAC) and poly-ferric sulfate (PFS), was applied. However, the effluent did not meet the reinjection requirements for suspended solids (SS) ≤ 2 mg/L, oil ≤ 6 mg/L and median diameter d50 ≤ 1.5 μm according to the water quality standard for oilfield injecting waters in clastic reservoirs (SY/T 5329–2012). The presence of adsorbed surfactant (betaine) and polymer (hydrolyzed polyacrylamide, HPAM) on oil and suspended solids increased the difficulties in agglomeration and charge-neutralization. In addition, water quality deterioration occurred within 5 h leading to increased turbidity, suspended solids and d50. X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis implied that water quality deterioration was caused by souring (producing sulfide), leading to the generation of suspended solids mainly containing sulfur and calcium carbonate (CaCO3). To address these challenges, the pre-ozonation coagulation (POC) and hybrid ozonation-coagulation (HOC) processes were compared. The effluent from both processes, using either PAC or PFS, met the reinjection requirements while inhibiting water quality deterioration. Additionally, higher removal efficiency and significantly reduced optimal ozone dosage were also achieved in the HOC process compared with the POC process. The enhanced generation of hydroxyl radicals (•OH) and polymeric hydrolysed coagulant species in the HOC process contributed to higher removal efficiency of HPAM, betaine and COD. Kinetics analysis revealed that •OH oxidation and coagulation played important roles in betaine and HPAM removal, respectively. The reaction pathways of betaine and HPAM in the ozonation and HOC processes were also analysed. Furthermore, the HOC process can effectively inhibit the accumulation of small molecular weight organic matter, facilitating the simultaneous coagulation.

Bubbleless aerated-biological activated carbon as a superior process for drinking water treatment in rural areas

Drinking water supply in rural areas remains a substantial challenge due to complex natural, technical and economic conditions. To provide safe and affordable drinking water to all, as targeted in the UN Sustainable Development Goals (2030 Agenda), low-cost, efficient water treatment processes suitable for rural areas need to be developed. In this study, a bubbleless aeration BAC (termed ABAC) process is proposed and evaluated, involving the incorporation of a hollow fiber membrane (HFM) assembly within a slow-rate BAC filter, to provide dissolved oxygen (DO) throughout the BAC filter and an increased DOM removal efficiency. The results showed that after a 210-day period of operation, the ABAC increased the DOC removal by 54%, and decreased the disinfection byproduct formation potential (DBPFP) by 41%, compared to a comparable BAC filter without aeration (termed NBAC). The elevated DO (> 4 mg/L) not only reduced secreted extracellular polymer, but also modified the microbial community with a stronger degradation ability. The HFM-based aeration showed comparable performance to 3 mg/L pre-ozonation, and the DOC removal efficiency was four times greater than that of a conventional coagulation process. The proposed ABAC treatment, with its various advantages (e.g., high stability, avoidance of chemicals, ease of operation and maintenance), is well-suited to be integrated as a prefabricated device, for decentralized drinking water systems in rural areas.

Integrated Membrane-adsorption system as a sustainable development approach for semiconductor-industry wastewater treatment

Conventional coagulation and flocculation processes applied for semiconductor industry wastewater treatment contributes to high operating cost due to the use of chemical coagulant and the need of schedule waste disposal. On top of that, precious nano-sized silica particles contain in the semiconductor-industry wastewater is also unable to recover through these processes. The aim of this study is to investigate the efficiency of integrated membrane-adsorption system as a sustainable development approach for semiconductor-industry wastewater treatment. The integrated system consists of two stages, membrane filtration unit followed by GSC adsorption unit. Membrane filtration unit mainly use for the wastewater treatment and silica recovery, whereas GSC is further use for the polishing of semiconductor-industry wastewater. The performance of integrated membrane-adsorption system is evaluated based on the rejection of different water quality parameters. Ceramic ultrafiltration membranes at 0.02 µm and 0.1 µm pore size were tested, while GSC adsorption was performed at three different bed heights (2 cm, 4 cm, and 6 cm). 0.02 µm membrane has greater rejection than 0.1 µm membrane with the removal of 99.25 % TSS, 99.53 % color, 99.91 % turbidity, 100 % COD, 93.97 % ammonia–nitrogen, and 99.8 % nitrate-nitrogen. For the system with a 6 cm bed height, further GSC adsorption achieved excellent results, with the removal of 100 % TSS, 99.8 % color, 99.98 % turbidity, 100 % COD, 97.5 % ammonia–nitrogen, and 99.89 % nitrate-nitrogen. The semiconductorindustry wastewater treatment employing an integrated membrane-adsorption system manage to produce treated water comply to Singapore's NEWater Quality which able to recycle and reuse internally in semiconductor industry.

Enhanced coagulation and oxidation by the Mn(VII)-Fe(III)/peroxymonosulfate process: Performance and mechanisms

To improve the performance of the conventional coagulation process, a permanganate (Mn(VII)) pre-oxidation combined with Fe(III)/peroxymonosulfate (PMS) coagulation process (Mn(VII)-Fe(III)/PMS) that can significantly improve the removal of dissolved organic carbon (DOC), turbidity, and micropollutants is proposed in this study. Compared with conventional Fe(III) coagulation, the Mn(VII)-Fe(III)/PMS process can also significantly enhance the removal of iohexol and sulfamethoxazole in raw water. During this process, the primary reduction product, Mn(IV), after Mn(VII) pre-oxidation was adsorbed on the floc surfaces and involved in the Fe(III)/PMS process. The natural organic matter (NOM) in raw water mediated the redox cycle of iron. The synergistic effect of NOM, Fe, and Mn facilitated the redox cycle of Mn(III)/Mn(IV) and Fe(III)/Fe(II) to promote the activation of PMS. The sulfate radical (SO4•−) played an important role in the degradation of micropollutants. The formation potential of the detected volatile disinfection by-product (DBP) during the subsequent chlorination was reduced by 21.9% after the Mn(VII)-Fe(III)/PMS process. This study demonstrated the promising application of the Mn(VII)-Fe(III)/PMS process for coagulation and micropollutant control and illustrated the reaction mechanism. This study provides guidance for improving conventional drinking water treatment processes.

Enhanced phosphate removal by coral reef-like flocs: Coagulation performance and mechanisms

In order to meet stricter phosphorus discharge standards for wastewater treatment plant effluent and better protect natural aquatic environments, this study investigated the coagulation performance and mechanisms of coral reef-like flocs formed in a continuous dosing coagulation (CDC) process. The CDC process exhibited enhanced phosphorus removal compared to the conventional coagulation (CC) process. To meet the 0.3 mg/L total phosphorus discharge standard, the CDC dosage (2 mg Al/L) was half the CC dosage (4 mg Al/L). Furthermore, at 4 mg Al/L, the CDC process obtained a very low total phosphorus concentration (0.035 mg/L). The CDC process had better phosphate removal performance when the initial pH was 6 or 5, and exhibited steady phosphate removal in the presence of organics and various ions. The CDC process enhanced phosphate removal in the following two ways. First, the “low pH and low Al3+ concentration” environment in the early stage benefited the co-precipitation of monomeric Al species and phosphate to form insoluble AlPO4 particles. Second, the coral reef-like flocs formed in the continuous dosing process had a stronger positive charge (2.3 mV) and larger specific surface area (264.11 m2/g). The enhanced absorption ability towards undissolved AlPO4 particles and dissolved phosphate anions promoted the overall phosphate removal of the CDC process. The coral reef-like flocs formed by a continuous dosing method provided new insights into the advanced treatment of dissolved contaminants in wastewater.

Dosing low-level ferrous iron in coagulation enhances the removal of micropollutants, chlorite and chlorate during advanced water treatment

Drinking water utilities are interested in upgrading their treatment facilities to enhance micropollutant removal and byproduct control. Pre-oxidation by chlorine dioxide (ClO2) followed by coagulation-flocculation-sedimentation and advanced oxidation processes (AOPs) is one of the promising solutions. However, the chlorite (ClO2–) formed from the ClO2 pre-oxidation stage cannot be removed by the conventional coagulation process using aluminum sulfate. ClO2– negatively affects the post-UV/chlorine process due to its strong radical scavenging effect, and it also enhances the formation of chlorate (ClO3–). In this study, dosing micromolar-level ferrous iron (Fe(II)) into aluminum-based coagulants was proposed to eliminate the ClO2– generated from ClO2 pre-oxidation and benefit the post-UV/chlorine process in radical production and ClO3– reduction. Results showed that the addition of 52.1-µmol/L FeSO4 effectively eliminated the ClO2– generated from the pre-oxidation using 1.0 mg/L (14.8 µmol/L) of ClO2. Reduction of ClO2– increased the degradation rate constant of a model micropollutant (carbamazepine) by 55.0% in the post-UV/chlorine process. The enhanced degradation was verified to be attributed to the increased steady-state concentrations of HO· and ClO· by Fe(II) addition. Moreover, Fe(II) addition also decreased the ClO3– formation by 53.8% in the UV/chlorine process and its impact on the formation of chloro-organic byproducts was rather minor. The findings demonstrated a promising strategy to improve the drinking water quality and safety by adding low-level Fe(II) in coagulation in an advanced drinking water treatment train.

Treatment of industrial electroplating wastewater for metals removal via electrocoagulation continous flow reactors

AbstractA real industrial electroplating rinsing wastewater was collected and subjected to physical and chemical examination. The study showed that it can be categorized as high strength wastewater, at pH- 2, COD 1430 mg/l, and high level of metals above permissible limits, namely: 150, 30, 25, and 2.9 for Ni, Cu, Zn, and Fe mg/l respectively. Therefore, metals must be adequately removed before discharging to avoid any hazardous impact on the environment. Similar synthetic wastewater was prepared to study the effect of chemical coagulation for the precipitation of metals. The optimum removal rate was achieved by using a combination of lime and ferric chloride at 100 and 30 mg/l respectively. The chemically treated electroplating wastewater was subjected to an electrocoagulation study. A comparison between iron and stainless-steel electrodes for the removal of metals was investigated. Furthermore, the effect of different electric voltages, and contact time on metals removal efficiency were also examined. It was found that the optimum removal capacity was achieved when a stainless steel electrode was employed in the presence of ferric chloride as coagulant, at 10 volts, 30 min. contact time, and pH 9 for synthetic solution. In a batch treatment system, the real industrial wastewater was treated at the predetermined optimum operating conditions; the removal of metals was 92.1%, 87.8% and 82.9% for Ni. Zn, and Cu respectively. By employing a continuous flow reactor for the treatment of the same real wastewater and under the same operating conditions, metals removal rate increased to 98.9%, 97.4% and 96.6% for Ni. Zn, and Cu respectively. The level of metals in the final treated wastewater copes with Egyptian Environmental Regulation. The overall results confirmed that the electro-coagulation (EC) technology offers an effective alternative process in combination with the conventional chemical coagulation process for reaching high removal performance of toxic metals from the electroplating wastewater. The advantage of EC technique is achieving high treatment efficiency instead of expensive chemical reagents, high construction cost and/or other conventional processes. In addition, the final treated water can be reused for rinsing process in the electroplating industry and/or discharging without any environmental hazard effect. It is also recommended to employ solar energy instead of electricity to reduce cost of operation.

Assessing the performance of coral reef-like floc towards the removal of low molecular weight organic contaminant

The removal of low molecular weight (MW) organics by coagulation is always a challenge in water treatment. In this study, we proposed a novel coagulation strategy: continuous dosing coagulation (CDC). The metallic coagulant and alkali were continuously dosed into water that was pre-acidized, rather than adding all the coagulant and alkali at once as in conventional coagulation (CC). The CDC process promoted the removal of different low MW organics, performing 15% better than the CC process. The best performance occurred at initial pH 6 and the coagulant dosing rate was 2 mg/(L·min). Under optimal conditions, the continuously dosed coagulant formed medium polymer Al in the early stages, which bound low MW organics to form complexes. Then, the subsequently dosed coagulant could adhere to the primary complexes and form coral reef-like surfaces with higher zeta potential and specific surface area. Each freshly formed surface bound contaminants and covered the previous surface. As a result, more dissolved low MW organic contaminants were included in the interior of flocs. However, in the CC process, all the coagulant was dosed at once, resulting in the rapid formation of aluminum hydroxide clusters, which had cotton-like surfaces with fewer binding sites. To achieve similar organic removal in treating secondary effluent, the CDC dosage was half of the CC dosage, indicating the potential economic benefits. The CDC process is a promising technology and the application in various water treatments should be further investigated.

Carbon Benefits of Drinking Water Treatment Electrification

Water treatment electrification, or the substitution of chemically-driven processes for electricity-driven processes to produce equivalent water quality, will be critical to decarbonizing our water supply. This work quantitatively assesses the carbon reduction potential of electrified unit processes for the removal of suspended solids, divalent ions, and organic compounds relative to chemically-intensive conventional coagulation, softening, and sorption processes. Several electrified technologies─including electrocoagulation, nanofiltration, and packed tower aeration─already reduce carbon emissions relative to the corresponding chemically-driven treatment processes under certain water quality conditions. Other electrified substitutes increase net carbon emissions for the carbon intensity of the 2020 grid but will reduce carbon emissions by 2050 as the electricity grid decarbonizes over the expected lifespan of the unit process. For electrified processes that are more carbon intense than conventional processes, we identify electricity consumption targets that would yield breakeven carbon emissions. Finally, we evaluate the potential for intensified treatment technologies (e.g., use of nanofiltration for simultaneous organics concentration reduction and divalent ion removal) to reduce carbon emissions when a single purpose application would not.

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.

Lastik Üretiminden Kaynaklanan Sürfaktan İçeren Atık Suların Koagülasyon Bazlı Arıtma Alternatiflerinin PROMETHEE Yaklaşımı ile Değerlendirilmesi

In this study, the treatment of wastewater containing surfactant used to prevent the sticking of the raw material pulp pressed in the tire production process, with conventional coagulation and microwave oxidation-supported electrocoagulation processes was investigated. The processes were optimized to ensure maximum chemical oxygen demand removal by the Taguchi experimental design method (L8). With Pareto analysis, it was found that the most effective parameter in microwave oxidation-supported electrocoagulation processes is microwave duration while the most effective parameter in the conventional coagulation process was FeCl3.7H2O dose. Analysis of variance found that the models determined for both processes were significant in explaining chemical oxygen demand removal. The appropriate process has been determined as the microwave oxidation-supported electrocoagulation, with the PROMETHEE method considering the optimum experimental conditions, chemical oxygen demand removal, chemical sludge production, operating cost and the preferability criteria of the processes. In microwave oxidation-supported electrocoagulation process, under optimum conditions, chemical oxygen demand removal efficiency, the amount of sludge production and operating costs were found as 66.9 %, 6.27 g / L and 1.195 € / L, respectively. It was determined that the criteria of chemical oxygen demand removal efficiency and sludge amount had a positive effect on the selection of the process.

A novel peroxymonosulfate (PMS)-enhanced iron coagulation process for simultaneous removal of trace organic pollutants in water

Conventional coagulation process is not effective to eliminate trace organic compounds (TrOCs). This study proposed a novel peroxomonosulfate (PMS) amended iron coagulation process and found its effectiveness in eliminating TrOCs in synthetic and natural waters. In synthetic waters containing hydroquinone (HQ) or benzoquinone (BQ), Fe(III)/PMS effectively degraded carbamazepine (CBZ), a representative of resistant TrOCs. The step of reduction of Fe(III) to form Fe(II) governed the degradation rate of CBZ as PMS activation by Fe(II) was the dominant reaction to generate SO4•-, which was the major reactive oxidant in the system. Meanwhile, HQ was quickly transformed to BQ in the Fe(III)/PMS system and BQ acted as an electron shuttle to induce Fe(III)/Fe(II) redox cycle and accelerate PMS activation. Natural organic matter (NOM) bearing phenolic and quinone moieties played similar roles as HQ and BQ and fast CBZ degradation was also observed. Finally, two surface waters spiked CBZ were subjected to bench-scale experimentation to simulate coagulation/flocculation/sedimentation processes in water treatment plants. Compared to the conventional iron coagulation process, the PMS-amended iron coagulation process increased the removal percentage of CBZ by 50%–80%. Overall, this study demonstrates that PMS enhanced iron coagulation is a promising process for the abatement of TrOCs in water treatment.

Coagulation and Electrocoagulation Process for Dye Removal fromTextile Wastewater: A Review

The synthetic textile dye wastewater using the azo dye, Congo red dye, methylene blue for laboratory experiment. The methods used in synthetic wastewater treatment conventional coagulation and electrocoagulation process. Electrocoagulation reactor two rods used aluminum and iron for anode and cathode, electrolysis time (2-30min), initial dye concentration (50 to 400mg/l),current density( 5,10,15 mA/cm2),room temp250C,mixing speed 500 rps. Chemical used in process Nacl, HCL, H2SO4, pH (6-8). Conventional coagulation process is used alum and Fecl3. The results show the electrocoagulation process is 90% wastewater removal compare to conventional coagulation.

Towards a comparison between the hybrid ozonation-coagulation (HOC) process using Al- and Fe-based coagulants: Performance and mechanism

In this study, the removal performance of a hybrid ozonation-coagulation (HOC) process using AlCl36H2O (Al–HOC) and FeCl36H2O (Fe–HOC) as coagulants for the treatment of wastewater treatment plant (WWTP) effluent and ibuprofen (IBP) was investigated. Compared with the conventional coagulation process and pre-ozonation-coagulation process, much better organic matter removal performance can be achieved for both the Al–HOC and Fe–HOC processes. The Fe–HOC process showed an obviously higher dissolved organic carbon (DOC) removal efficiency than that of the Al–HOC process. Surface hydroxyl groups were determined to be the active sites in generating OH in the HOC process, and the hydrolysed Fe species possessed a higher content of surface hydroxyl groups than the hydrolysed Al species according to fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectra (XPS) analyses. In addition, the hydrolysed Fe species contained a higher portion of tetrahedral sites that were more likely to be stronger Lewis acid sites to react with ozone to generate OH. Furthermore, peroxone reactions in the HOC process were other possible way to enhance the OH generation, and higher H2O2 generation was observed in the Fe–HOC process due to higher O2− generation. Therefore, better removal performance of the Fe–HOC process can be obtained due to the increased OH generation in the Fe–HOC process.

Impact of coagulant type and magnetic ion exchange (MIEX) pre-treatment on floc strength and structure at the Kluizen Water Treatment Plant, Belgium

Drinking water supplied to the community should be free from Disinfection ByProducts (DPB). DPB occurs when organic matter is present in surface water and reacts with chlorine. Conventional coagulation and flocculation processes have been used in water treatment plants to remove organic matters from raw water. Recently, Magnetic Ion Exchange (MIEX) followed by coagulation and flocculation has started to attract attention since it improves natural organic matter removal and decreases coagulant demand. The efficiency of NOM removal and downstream processes not only depends on the prior removal process of organic matter but also on the structure , size and strength of flocs formed in the coagulation process as well. This study aims at comparing (1) floc structures (i.e. floc sizes, floc strength, and fractal dimensions) generated from coagulation of raw water and (2) water pre-treated with magnetic ion exchange obtained from Kluizen water treatment plant (Kluizen, East-Flanders, Belgium). The floc sizes during growth, breakage and re-growth were measured using (laser) light scattering (Malvern Mastersizer 2000), coupled with jar test equipment. The strength of flocs was evaluated by empirically relating the floc size to the increased shear rate applied. The results show that pre-treated water coagulated with all the coagulants produces flocs with larger sizes compared to the flocs generated from raw water. For both water types, FeCl3 gave better recoverability after breakage than PACl and AlCl3. After pre-treatment, the floc size was increased by 19%, 63% and 64% forthe coagulants such as PACl, AlCl3, and FeCl3, respectively. Coagulation process with PACl generated flocs with higher fractal dimension and lower strength constants which indicates that flocs generated is strong and compacted micro-flocs. The floc size measurement techniques and coagulation system were found to have an impact on the resulting floc sizes.

Enhanced Coagulation with Mn(III) Pre-Oxidation for Treatment of Micro-Polluted Raw Water

Mn(III) oxidation technology has attracted increasing interest in recent years because of its fast decontamination kinetics and second-pollution-free characteristic. Whether it can be used as a pre-oxidation step to enhance conventional coagulation process remains to be evaluated. Herein, an Fe-coagulation/sedimentation process combined with Mn(III) pre-oxidation (Mn(III)+C/S), hypochlorite pre-oxidation (Cl2+C/S), and permanganate pre-oxidation (PM+C/S) was applied to treat simulated micro-polluted raw water. The removal performance of routine water quality indices (turbidity, dissolved organic carbon, total nitrogen, nitrate-nitrogen, ammonia-nitrogen, Pb(II), and Cr(VI)) and the emerging pollutants (acesulfame, carbamazepine, bisphenol S, and nano-ZnO) created by these three processes were researched. The mechanism of how Mn(III) pre-oxidation influences C/S was explored by identifying the transformation products of Mn(III), measuring the timely variation of flocs’ zeta potential and size, and scanning flocs’ micromorphology. Compared to Cl2+C/S and PM+C/S, Mn(III)+C/S exhibited its superiority in removing dissolved organic carbon (72.9%), total nitrogen (31.74%), and emerging pollutants (21.78%–93.49%). The enhanced removal of these contaminants by Mn(III)+C/S found its explanation in the strong oxidation power of Mn(III) and the multiple roles of in-situ formed MnO2 (e.g., flocculation core, adsorption co-precipitant, and densification agent). The acute toxicity tests confirmed that water treated by Mn(III)+C/S did not show a significant change in the associated toxicity. The findings of the present study indicate that Mn(III) oxidation technology shows great potential as an alternative to pre-oxidation technology of waterworks.

Comparison of conventional coagulation and electrocoagulation methods for dewatering of coal preparation plant

This study compares the results of the dewatering of coal preparation plants tailings by conventional coagulation processes using different types of coagulants and by electrocoagulation methods carried out by two different electrodes. When the results of electrocoagulation and conventional coagulation experiments were compared (aluminium electrode vs. ferric chloride), it was found that the coagulation efficiencies for both methods were similar, in the case that the aluminium electrode was used, there was a 22.2% decrease in the process cost compared to the use of ferric chloride.

Effects of Chemical Functionalization of MWCNTs on the Structural and Physical Properties of Elastomeric Copolyetherester-based Composite Fibers

Elastomeric copolyetherester (CPEE)-based composite fibers incorporating various neat and functionalized multiwalled carbon nanotubes (MWCNTs) were prepared through a conventional wet-spinning and coagulation process. The influence of functionalized MWCNTs on the morphological features, and the thermal, mechanical properties and electrical conductivity of CPEE/MWCNT (80/20, w/w) composite fibers were investigated. FE-SEM images show that a composite fiber containing poly(ethylene glycol)-functionalized MWCNTs (MWCNT-PEG) has a relatively smooth surface owing to the good dispersion of MWCNT-PEGs within the fiber, whereas composite fibers including pristine MWCNTs (p-MWCNT), acid-functionalized MWCNTs (a-MWCNT), and ethylene glycol-modified MWCNTs (MWCNT-EG) have quite a rough surface morphology owing to the presence of MWCNT aggregates. As a result, the CPEE/MWCNT-PEG composite fiber exhibits noticeably increased thermal and tensile mechanical properties as well as a faster crystallization behavior, which stems from an enhanced interfacial interaction between the CPEE matrix and MWCNT-PEGs.

Comparing Fenton Oxidation with Conventional Coagulation Process for RR198 Dye Removal from Aqueous Solutions

Comparing Fenton Oxidation with Conventional Coagulation Process for RR198 Dye Removal from Aqueous Solutions