Optimum Removal Efficiency Research Articles

Palm oil mill effluent treatment using combination of low cost chickpea coagulant and granular activated carbon: Optimization via response surface methodology

This work evaluates the efficiency of a novel treatment method for raw POME based on coagulation and adsorption process. The chemical oxygen demand (COD) and colour reduction of POME using chickpea as coagulant in the coagulation–flocculation pre-treatment was evaluated. The adsorption of the remaining contaminants in the coagulated POME was done by using granular activated carbon (GAC). To achieve the optimum process variables and desired process status, Central Composite Design (CCD) of the Response Surface Methodology (RSM) was applied. The optimum removal efficiency parameters using chickpea were found to be 2 g, pH 6, and mixing speed of 150 rpm. Under these conditions, the COD and colour in POME were reduced by 44% and 54%, respectively. On the other hand, the findings from batch study show that pH 4 and 15 g GAC was the optimum pH and dosage at 4 h of contact time for COD (88%) and colour (91%) removal of the chickpea pretreated POME. ANOVA statistical outputs revealed the quadratic response function introduced significant responses for color and COD at the accuracy of 95% with p-values ≤ 0.05 for both cases. The findings proposed that the combined coagulation–adsorption treatment as an efficient, inexpensive and eco-friendly alternative for raw POME treatment. Evaluation of the adsorption equilibrium in the course of colour and COD removal by means of GAC was performed by using both Langmuir and Freundlich isotherms. However, the results are indicating that the Langmuir isotherm model is more accurate to describe the removal processes.

Improving nanoplastic removal by coagulation: Impact mechanism of particle size and water chemical conditions

Plastic particles may bring potential threats to the ecosystem. Coagulation, as a widely used method to remove particles, has been rarely studied for plastic particles in the nanometer range. In this work, the coagulation removal of polystyrene nanoplastic particles (PSNPs, 50–1000 nm) was conducted in a model system containing coagulants aluminum chlorohydrate (PAC) and polyacrylamide (PAM). The optimal removal efficiency (98.5%) was observed in the coagulation process at pH= 8.0, 0.4 g·L−1 PAC and 20 mg·L−1 PAM. The inhibition impact of humic acid was also noticed, due to its competitive adsorption with PSNPs onto flocs. The interaction energies between PSNPs and PAC were calculated by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, which showed that electrical neutralization resulted in the difference of the remove efficiency in different sizes and coagulant concentrations. The formation of Al-O bond between PSNPs and PAC/PAM flocs promoted the removal of PSNPs. Excessive PAM (> 20 mg·L−1) increased clusters size and solution viscosity, which resulted in the settling of clusters being controlled by buoyancy and the reduced remove efficiency. The findings suggest that the chemical coagulation dominants the removal of NPs, and the coagulation efficiency can be optimized by choosing suitable coagulant and water chemical conditions.

Synthesis and characterization of Bi2SiO5-coated Ag/AgBr photocatalyst with highly efficient decontamination of organic pollutants

In this work, a novel nanoscale leaf-like ternary Bi2SiO5/Ag/AgBr photocatalyst was synthesized by means of the hydrothermal reaction together with an in situ photoreduction procedure. The ternary Bi2SiO5/Ag/AgBr composites possessed a neoteric heterostructure, in which the surface of AgBr was wrapped with nano-sheet Bi2SiO5. Through the coating of Bi2SiO5, the growth of AgBr nanoparticles was hindered, thereby inhibiting the agglomeration. In ternary composites, the particle size of Ag/AgBr obviously decreased, which reduced from 5 um to 0.6 um, approximately. The above effects of Bi2SiO5 on the morphology of Ag/AgBr were conducive to increasing the chance of contact between the active center and the reactant, thus promoting photocatalytic activity. Systematic researches showed that the BA 1–5 (the composite with a Bi2SiO5/Ag/AgBr molar ratio of 1:5) exhibited the optimal removal efficiency for RhB degradation, which was 5.97 times and 3.28 times that of Ag/AgBr and Bi2SiO5, respectively. Co-effect of the surface plasmon resonance (SPR) induced by Ag0 as well as formed heterojunction composed of Bi2SiO5, AgBr and Ag also contributed a lot in the splendid light absorption of ternary composites. H2-TPR analysis indicated that the reduction ability of Ag/AgBr was further enhanced, comparing with that of bare Ag/AgBr. This present work can provide an original approach to devise and manufacture the Ag/AgBr-based photocatalysts.

Optimisation of operating conditions during coagulation-flocculation process in industrial wastewater treatment using Hylocereus undatus foliage through response surface methodology.

In exploring the application of natural coagulants in industrial wastewater treatment, plant-based coagulants have been gaining more interests due to their potential such as biodegradability and easy availability. Hylocereus undatus foliage as a plant-based coagulant has been proven to be efficient during the coagulation-flocculation process; however, limited research has been reported focusing only on palm oil mill effluent (POME) and latex concentrate wastewater. In addition, no previous study has been carried out to determine the performance evaluation of Hylocereus undatus foliage in treating different types of wastewater incorporating different operating conditions using optimization techniques. Hence, this study employed response surface methodology (RSM) in an attempt to determine the performance evaluation of the coagulant in paint wastewater treatment. Four independent factors such as the pH value, coagulant dosage, rapid mixing speed and temperature were chosen as the operating conditions. Three water parameters such as turbidity, chemical oxygen demand (COD) and suspended solids (SS) were chosen as responses in this study. Results revealed that through central composite design (CCD) via Design Expert software, the optimum conditions were achieved at pH 5, coagulant dosage of 300mg/L, rapid mixing speed of 120rpm and temperature at 30°C. The experimental data was observed to be close to the model predictions with the optimum turbidity, COD and SS removal efficiencies found to be at 62.81%, 59.57% and 57.23%, respectively.

Investigation on the performance evaluation of vertical subsurface flow constructed wetland for the treatment of rural wastewater.

In a rural country like India, low cost and decentralized treatment units like the vertical subsurface flow constructed wetland (VSSF CW) can be reflected as a novel wastewater system. In this concern, a pilot-scale VSSF CW unit of size 0.92 m × 0.92 m × 0.85 m bed planted with Typha latifolia and Phragmites australis was operated for a 12-month duration to treat simulated rural wastewater. During the operation, a constant head arrangement was made to maintain a continuous flow to achieve 5 different Hydraulic Retention Times (HRTs) of 2, 4, 6, 8 and 10 days in each season, such as winter, summer and rainy, to investigate the performance of the unit under different retention times. The reactor showed optimum removal efficiency at 6 days HRT at 12.5 cm/day Hydraulic Loading Rate (HLR) for organic matter removal. Both macrophytes and the microbial biomass of filter media effectively treated the rural wastewater. Average removal efficiency of the reactor during the entire study was 64.73%-88.80% for Chemical Oxygen Demand, 74.96%-95.34% for Biochemical Oxygen Demand, 40.13%-79.45% for Ammonia Nitrogen, 25.36%-65.65% for Total Kjeldahl Nitrogen, 22.86%-58.48% for Phosphate phosphorus, 23.50%-55.45% for Total phosphorous, 74.91%-98.59% for Faecal Coliforms and 71.14%-95.31% for Total Coliforms respectively. Two-way ANOVA followed by post-hoc Tukey's test showed that HRT had a significant impact on removal efficiency but not the season. Overall performance of the unit was good and study suggested that VSSF CW can be a smart alternative technology to treat rural wastewater before final disposal.

The effect of co-pyrolysis temperature for iron-biochar composites on their adsorption behavior of antimonite and antimonate in aqueous solution

Iron-biochar is an efficient adsorbent for contaminants, whereas the role of prepared temperature on removal of antimony (Sb) is unacquainted. In this study, the iron-biochar composites (FBC) were fabricated by co-pyrolysis at 500°C and 800°C and applied to remove antimonite (Sb(III)) and antimonate (Sb(V)) in aqueous. The results showed Fe3O4 was loaded on biochar prepared at 500°C (FBC500), while FeOOH with zero-valent iron (ZVI) was formed on biochar pyrolyzed at 800°C (FBC800). However, FBC500 showed the maximum absorbance for Sb(V) (30.47 mg/g), and FBC800 had optimal removal efficiency for Sb(III) (52.30 mg/g). The sorption of Sb(III) and Sb(V) on FBC was multilayer heterogeneous chemisorption (complexation and ligand exchange). Sb(III) was oxidized to Sb(V) with less toxicity during the corrosion of ZVI on FBC800, leading to the co-precipitation of Sb2O5. The electrostatic interaction affected the adsorption of Sb(V) on FBC500 and FBC800. The FBC800 showed superior reusability and resistance than FBC500.

Low cost electrocoagulation process for treatment of contaminated water using aluminium electrodes from recycled cans

Electrocoagulation has been used to successfully treat diverse types of wastewaters. This treatment is carried out when there is an electro-dissolution of soluble anodes to form metal hydroxide flocks within the effluent. In this work an electrocoagulation setup was used to treat water from a contaminated stream. Aluminium anodes produced from recycled cans were used as electrodes. The contact time and voltage during electrocoagulation were varied and the corresponding effects on pH, Total Dissolved Solids (TDS), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and electrode weight gain/loss were observed. The average TDS of the raw water before Electrocoagulation was 286.7 mg/L. At 10 V, 20 V and 30 V, the average TDS of 246.3 mg/L, 227.3 mg/L and 220.7 mg/L were obtained after 120 min of electrocoagulation. The reduction in TDS signified improved anode dissolution and thus improved water quality. The results show that optimum COD and BOD removal efficiencies of 90.7% and 97.67% were obtained at 10 V.

Development and optimization of sewage wastewater treatment program

In this study, a wastewater treatment program was developed and optimized for the treatment of sewage wastewater. Central composite face design (CCFD) and response surface methodology (RSM) were utilized to develop the experimental design and to establish the relationship between the independent variables (coagulant and flocculant dosage) and responses (turbidity and total dissolved solids removal). Statistical analysis showed that the developed response models were accurate. Optimal removal efficiencies of 93.3% and 23.2% for turbidity and TDS, respectively, were obtained under the optimal conditions for coagulant (120.9 ppm of U6750) and flocculant (125 ppm of Floc887) dosage. This showed that the developed treatment using the coagulant, U6750 and flocculant, Floc887 improved the physical characteristics of the wastewater.

Phosphorus recovery and iron, copper precipitation from swine wastewater via struvite crystallization using various magnesium compounds

Swine wastewater contains phosphorus, ammonia nitrogen, and heavy metals that affect the struvite purity produced from the wastewater and increase the ecological hazards. In addition, struvite crystallization process is highly dependent on the usage of magnesium sources. Thus, it is necessary to explore the effects of three magnesium sources, including MgCl2, Mg(OH)2 and MgO, on the phosphorus recovery and minimizing Cu and Fe contents via struvite crystallization process. The observations revealed that the predominant parts of Cu and Fe precipitate in the form of hydroxide during pH adjustment. Meanwhile, when using MgCl2 as the magnesium source, the optimal removal efficiency of phosphorus reached 94.55%, followed by MgO and Mg(OH)2. Simultaneously, 90.60% Cu and 98.80% Fe precipitate under MgCl2 as magnesium source. The redissolution behavior of Cu occurs when MgO and Mg(OH)2 are used as magnesium sources, increasing the Cu concentration. The smallest operation cost is from MgCl2 as magnesium source. The potential environmental impact analyzed by life cycle assessment method shows that MgCl2 in struvite crystallization process saves more fossil energy and protects resource while lessens the nature's eutrophication risk. The technical, economic, and environmental assessments confirm MgCl2 as a promisable source of magnesium in struvite crystallization process for achieving cleaner production goal.

Electrokinetic remediation of Cd-contaminated soil using low voltage gradients coupled with array adsorption zone and polarity exchange

Soil Cd pollution is a threat to the global ecological environment. Electrokinetic remediation (EKR) generally uses strong electric fields to obtain high removal efficiency, which leads to a series of side reactions and high energy consumption. EKR using low-voltage gradients showed weak migration of Cd and low remediation efficiency. Herein, to develop an effective enhanced EKR technology using low voltage gradient (0.2 V·cm−1), array adsorption zone and polarity exchange were applied simultaneously. Five experiments were conducted to determine the effect of polarity exchange, array adsorption zone and their combination on Cd removal when EKR was carried out at 0.2 V·cm−1. Results showed that the combined use of the array adsorption zone and polarity exchange achieved optimal remediation and average Cd removal efficiency was 83%. Moreover, the reciprocating motion of Cd caused by polarity exchange is no longer a side effect. In the wheat cultivation experiment, the Cd concentration of wheat root, stem and leaf decreased by 86%, 93% and 95% after Cd was removed by EKR coupled with array adsorption zone and polarity exchange. The 30-day energy consumption is 7.72 kWh·m−3, which is far lower than that of other enhancement methods. The present work proposes an effective EKR technology working at low voltage for Cd-contaminated soil.

Hybrid Photo-Fenton oxidation and biosorption for petroleum wastewater treatment and optimization using Box–Behnken Design

This study investigates the treatment of petroleum wastewater (PWTP) effluent using hybrid techniques (photo-Fenton oxidation and adsorption) to remove organic pollutants such as chemical oxygen demand (COD) and phenol. All the experiments were carried out in batch mode. The effects of pH, ferrous salt (Fe 2＋ ), and H 2 O 2 oxidation factors on the photo-Fenton process were studied. The response surface methodology (RSM) approach for experiment design and optimization yielded maximum COD and phenol removal at Fe 2＋ , H 2 O 2 , pH of 20 mM, 400 mM, and 3.8, respectively. In this optimal scenario, phenol reduction from the initial value of COD 12654.6 mg/L, phenol 213.0 mg/L was accomplished by 69.97% and 95.66%, respectively. Response surface methodology (RSM) photofenton based modeling and optimization was done using a Box–Behnken. The high coefficient of regression R 2 = 0 . 97 and 0.98 for COD and phenol oxidation is suggested by variance analysis (ANOVA). The PWTP effluent treated by Fenton oxidation with COD 4139.1 mg/L and phenol 70.1 mg/L was treated with Phragmites australis. Phragmites australis was chosen as an adsorbent. Phragmites australis was analyzed and characterized using several techniques, including Fourier transform infrared spectroscopy, Scanning Electron Microscopy, Zeta potential, and particle size distribution. The adsorption process step followed the photo-Fenton treatment process. The adsorption process achieved 69.04 % and 95.80% for COD and phenol removal. Kinetic studies showed that the statistics match very well in the nonlinear pseudo-first and second-order models based on the correlation coefficients (R 2 = 0 .999) and (R 2 = 0 .996), respectively, for COD and phenol removal in the adsorption phase. The severe adsorption potential for COD and phenol removal is 14421.97 mg/g and 374.90 mg/g, respectively. Finally, as a natural material, P. australis is a promising adsorbent material. • Box–Behnken Experimental Design (BBD) was used to determine the optimal removal efficiency for both COD and phenol for the photo-Fenton process. • Statistical analysis of the data indicated that H 2 O 2 significantly affected COD, phenol degradation for petroleum wastewater. • The optimum conditions for pH, Fe +2 , H 2 O 2 are 3.8, 20 mM, 400 mM for 69.97% COD, and 95.66% Phenol. • Phragmites australis was used as an adsorbent in the adsorption step. P. australis showed remarkable surface characteristics and adsorption ability. • The maximum adsorption capacity to remove COD and phenol of 14421.97, 374.90 mg/g, removal ratio 69.04%, and 95.80%, and the data fits very well in the nonlinear pseudo-first and second-order models.

Efficiency assessment of ZVI-based media as fillers in permeable reactive barrier for multiple heavy metal-contaminated groundwater remediation

Four zero valent iron-based composites were prepared and applied as the reactive media of permeable reactive barriers. Batch tests and continuous-flow column experiments were conducted to assess the long-term performance of these composites for possible utilization as fillers for PRB. The experimental results of the batch tests revealed that in single-metal systems, the removal efficiency of Cu(Ⅱ), Co(Ⅱ), Cr(Ⅵ) and As(Ⅲ) could reach 98% at equilibrium. Equilibrium data showed that composites displayed different selectivity values in binary and quaternary-component systems. For the continuous tests, column filled with chitosan-zero valent iron-based composites, exhibited optimal removal efficiency and achieved average removal values of 98.84%, 88.28%, 95.65% and 87.10% for Cu(Ⅱ), Co(Ⅱ), Cr(Ⅵ) and As(Ⅲ) during the whole 30-day operation, respectively. Dynamic removal improvement of multiple metals was observed with further assembly media, with average removal of 99.11%, 90.05% and 87.34% for Cu(Ⅱ), Co(Ⅱ) and As(Ⅲ), respectively. Combined with superficial characteristic analysis, the functional groups distributed on the surface of composites played a key role in metal sorption. Moreover, the adsorbed Cu(Ⅱ), Co(Ⅱ) and Cr(Ⅵ) gradually transferred to the mobile phase when the operational periods were prolonged, while As(Ⅲ) became more stable.

Facile synthesis of novel multifunctional β-cyclodextrin microporous organic network and application in efficient removal of bisphenol A from water

Here, a novel multifunctional β-cyclodextrin microporous organic network (CD-MON) has been successfully synthesized and used to remove bisphenol A (BPA) from water. The morphology and composition of the synthesized CD-MON were confirmed. The combination of hydrophobic interaction, π-π interaction inclusion mechanism and hydrogen bonding endowed CD-MON to exhibit superior adsorption capacity toward BPA. The adsorption kinetics and isotherms of BPA and other four model aromatic pollutants on CD-MON were studied. CD-MON could maintain adsorption efficiency toward BPA over wide pH ranges and without being affected by the ionic strengths, co-existing inorganic ions and humic acid. The optimal conditions and removal efficiency of BPA were screened by response surface analysis. In addition, nearly unchanged in the adsorption efficiency toward BPA was observed after five regeneration cycles on CD-MON. CD-MON can adsorb about 80% of five model aromatic pollutants from the water within 40 s in the flow-through experiments. This novel adsorbent gives great promise for practical wastewater remediation.

Evaluation of the efficiency of electrocoagulation process in removing cyanide, nitrate, turbidity, and chemical oxygen demand from landfill leachate

Background: Leachate contains toxic and non-biodegradable substances that are not easily treated by conventional treatment methods. This study investigated the effect of pH, current density, and reaction time parameters on the removal of cyanide (CN- ), nitrate (NO3- ), turbidity, and chemical oxygen demand (COD) from leachate by electrocoagulation process. Methods: This study was an experimental one with direct current using four parallel bipolar aluminum electrodes with 90% purity. The length, width, and thickness of the electrodes were 5 cm, 10 cm, and 2 mm, respectively. There were 6 holes with a diameter of 0.7 cm on each of the electrodes. The samples were prepared from the old leachate of solid waste landfill in Ghaemshahr, Iran. Results: In this study, at a current density of 33 mA/cm2 and a time of 60 minutes, the optimum removal efficiency of cyanide (100 %) was obtained at pH 5.5 and pH 10. Moreover, the maximum removal of nitrate (99.65 %) and turbidity (86.41 %) were at pH 5.5 and pH 8.3, respectively and the highest removal efficiency of COD (83.14 %) was obtained at pH 10. Conclusion: The results showed that the removal of cyanide, nitrate, turbidity, and COD increases with increasing current density and reaction time. Due to the proper removal of nitrate and cyanide from leachate by electrocoagulation, nitrate and cyanide amounts were less than the allowable contamination level. Based on the results, electrocoagulation is considered an efficient and effective method for removing nitrate and cyanide from old leachate of municipal solid wastes.

Functional genera for efficient nitrogen removal under low C/N ratio influent at low temperatures in a two-stage tidal flow constructed wetland

A two-stage tidal flow constructed wetland (referred to as TFCW-A and TFCW-B) was used to treat low chemical oxygen demand/total nitrogen (COD/TN or simply C/N) ratio influent at low temperatures (<15 °C). The influence of the flooding-resting time (A: 8 h–4 h, B: 4 h–8 h) and effluent recirculation on nitrogen removal and microbial community characteristics were explored. TFCW-B achieved optimal average nitrogen removal efficiency with effluent recirculation (96.05% ammonium nitrogen (NH4+-N); 78.43% TN) and led to nitrate nitrogen (NO3−-N) accumulation due to the lack of a carbon source and longer resting time. Ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were inhibited at low temperatures. Except for nrfA, AOA, AOB, narG and nirS were separated by the flooding-resting time rather than by spatial position. Furthermore, the dominant genera in TFCW-A were Arthrobacter, Rhodobacter, Pseudomonas, and Solitalea, whereas prolonging resting time promoted the growth of Thauera and Zoogloea in TFCW-B. Spearman correlation analysis showed that Zoogloea and Rhodobacter had the strongest correlations with other genera. Moreover, the NH4+-N concentration was significantly positively influenced by Arthrobacter, Rhodobacter, Pseudomonas, and Solitalea but negatively influenced by Thauera and Zoogloea. There was no significant correlation between TN and the dominant genera. This study not only provides a practicable system for wastewater treatment with a low C/N ratio but also presents a theoretical basis for the regulation of microbial communities in nitrogen removal systems at low temperatures.

Removal of Bismarck Brown G dye over composites of metalized copper oxide nanoparticles with nitrogen and activated carbons

The present work describes preparation of composites of iron metalized copper oxide nanoparticles (Fe/CuONPs) using co-precipitation method. Then new composites were prepared by combination of Fe/CuONPs with each of nitrogen and activated carbons(ACs). Activated carbons was both natural (AC1) and physically activated AC (AC2). This yielding tertiary systems N/Fe/CuONPs, AC1/Fe/CuONPs, and AC2/Fe/CuONPs. These prepared materials were investigated using different techniques and analytical methods such as Fourier transform infrared spectroscopy (FTIR), X- rays diffraction (XRD) technique, BET specific surface area, Scanning electron microscopy (SEM), Atomic absorption spectroscopy (AAS), and CHN microelemental analysis. The adsorption ability of these materials was investigated via following removal of Bismarck Brown G dye (BBG) from simulated industrial wastewaters over a suspension of these prepared materials. Different adsorption parameters and conditions were investigated such as effect of weight of adsorbent, effect of adsorption temperatures, and effect of pH of the dye solution. Besides that, adsorption isotherms were undertaken involving applying each of Langmuir and Freundlich adsorption isotherms was undertaken. From the obtained results it was found that, the optimum removal efficiency for this dye was noted when using AC2/Fe/CuONPs as adsorbent under these conditions. Also from adsorption isotherms, it was found that, the results were more fitted with Langmuir adsorption isotherm.

Optimum conditions of zero-valent iron nanoparticle stabilized foam application for diesel-contaminated soil remediation involving three major soil types

Stability of foam, enhanced by nano zero-valent iron (nZVI) and its optimized constituents, may have significant potential for effective treatment of soil contaminated with diesel oil-a major environmental problem. The optimum diesel removal efficiency from distinct types of soil accomplished by the unique application of such foams as well as the optimum conditions of the foaming constituents have not been reported in literature so far. Hence, in this work, the removal of diesel contaminant from different soil types (desert, coastal, clay soil) is optimized, and the optimized results are reported for the first time, using response surface methodology (RSM), for alkylpolyglucoside phosphate (APG-Ph) foam, stabilized by nZVI. The effect of concentrations of APG-Ph (0.02, 0.04, 0.06, 0.08, and 0.1 volume %) and nZVI (2, 3, and 3.5mg/l) on diesel removal efficacy from soil is studied using Box-Behnken design (BBD) of response surface methodology (RSM). Maximum diesel removal efficiency obtained at a concentration of 0.1 volume % APG-Ph foam with 3.5mg/l nZVI for desert, coastal, and clay soil is 94.6, 95.3, and 57.5%, respectively. The optimum concentrations of APG-Ph and nZVI are found to be 0.98 volume % and 0.8mg/l, respectively. Validation of this optimal condition experimentally results in highest removal efficiency of 98.3, 97.2, and 75.9% for desert, coastal, and clay soil respectively. This is in good agreement with the predicted values by RSM (98.67, 97.57, and 76.85%). The maximum diesel removal efficiency predicted at optimal concentration of APG-Ph and nZVI is significantly larger than the results reported in literature in last three years.

Elimination of Arsenic (III) using Phaseolus Lunatus and Phaseolus Vulgaris as Natural Coagulants

In this analysis, the efficacy of adding coagulants such as Phaseolus lunatus and Phaseolus vulgaris (polymers) to the coagulation process during the treatment of arsenic aqueous solution to extract the arsenic metal was investigated. Experiments were carried out to evaluate the output of Phaseolus lunatus and Phaseolus vulgaris, both individually and in combination with arsenic, using the standard Jar test protocol. P.lunatus and P.vulgaris were given doses ranging from 1 to 3 gm. For P.lunatus and P.vulgaris, the (optimal) removal efficiency for total arsenic in the aqueous solution was obtained at 2gm. With chemical affinity between arsenic and coagulants used in this process, the valence state of arsenic may affect removal efficiency during the chemical coagulation process. pH is discovered to be a significant factor that has a direct or indirect impact on results. By overcoming the isoelectric point, the complex formed by the interaction of the inorganic pollutant and organic coagulant may aid in the removal of arsenic at pH 9 and 8. P.lunatus and P.vulgaris had optimised arsenic initial concentrations of 57.1µg/L and 42.6µg/L, respectively. The coagulation mechanism is more prevalent in water treatment, as shown by the above findings.

The used automobile catalytic converter as an efficient catalyst for removal of malathion through wet air oxidation process

The automobile catalytic converter (ACC) contains a huge number of precious metals as catalysts. When an ACC fails to meet standards, it is removed from the exhaust of an automobile but retains some catalytic activity. However, the recovery and/or activation of this waste is a high-cost process and includes several chemical treatments. Catalytic wet air oxidation (CWAO) has been reported as an effective wastewater treatment method. The most important disadvantage of CWAO is cost-nonefficiency. Herein, to overcome these problems, the simple recovery of catalysts from waste ACC for reuse in CWAO was investigated. The optimum conditions of reaction were investigated through response surface methodology (RSM). The optimum removal efficiency was 88% when the reaction conditions were set on the 20 bar of pressure at 111.5 °C over 77 min and using 0.41 g of recovered catalyst. In addition, toxicity testing was performed on a model of malathion-contaminated wastewater before and after CWAO treatment. Final product identification was performed which showed that CWAO eliminated the toxicity of wastewater and was determined to be malaoxon, present at acceptable concentrations, and tributyl phosphate. In conclusion, there may be important potential for the use of recovered ACC catalyst in the treatment of toxic wastewater.

A New Polyvinylidene Fluoride Membrane Synthesized by Integrating of Powdered Activated Carbon for Treatment of Stabilized Leachate

Stabilized landfill leachate contains a wide variety of highly concentrated non-biodegradable organics, which are extremely toxic to the environment. Though numerous techniques have been developed for leachate treatment, advanced membrane filtration is one of the most environmentally friendly methods to purify wastewater effectively. In the current study, a novel polymeric membrane was produced by integrating powdered activated carbon (PAC) on polyvinylidene fluoride (PVDF) to synthesize a thin membrane using the phase inversion method. The membrane design was optimized using response surface methodology (RSM). The fabricated membrane was effectively applied for the filtration of stabilized leachate using a cross-flow ring (CFR) test. The findings suggested that the filtration properties of fabricated membrane were effectively enhanced through the incorporation of PAC. The optimum removal efficiencies by the fabricated membrane (14.9 wt.% PVDF, 1.0 wt.% PAC) were 35.34, 48.71, and 22.00% for COD, colour and NH3-N, respectively. Water flux and transmembrane pressure were also enhanced by the incorporated PAC and recorded 61.0 L/m2·h and 0.67 bar, respectively, under the conditions of the optimum removal efficiency. Moreover, the performance of fabricated membranes in terms of pollutant removal, pure water permeation, and different morphological characteristics were systematically analyzed. Despite the limited achievement, which might be improved by the addition of a hydrophilic additive, the study offers an efficient way to fabricate PVDF-PAC membrane and to optimize its treatability through the RSM tool.