Greater Removal Efficiency Research Articles

Chemical Precipitation removal of Boron in Synthetic Wastewater using Microwave Heating

Objectives : The objective of this study is to investigate the potential for the removal of boron(B) from synthetic wastewater through chemical precipitation using microwave heating to identify the optimal conditions for the removal of boron.Methods : Synthetic wastewater was prepared using boric acid(H3BO3) and distilled water. The range of variables that exert an influence on boron removal included the initial pH 3-13, the calcium hydroxide(Ca(OH)2) dosage of 0.5-10 g per 30 mL(17–333 g/L), and the boron concentration of 100-1,500 mg/L. A face-centered design in response surface method was employed to identify the optimal conditions for boron removal in a continuous scale and to ascertain the interaction of the factors.Results and Discussion : In discontinuous conditions, the maximum removal efficiency was observed at initial pH 3, Ca(OH)2 of 2 g, and the boron concentration of 1,500 mg/L. As the pH value decreased, the removal of boron increased. The greatest removal efficiency was observed when the dosage of Ca(OH)2 was 2-5 g. It was also found that the higher the concentration of boron, the greater the removal efficiency. In the continuous scale, the optimal conditions for boron removal were identified as initial pH 3.3, the dosage of 6.2 g Ca(OH)2, and the boron concentration of 1,500 mg/L, with the removal efficiency of 93%. All independent variables exerted a statistically significant influence on chemical precipitation removal(p<0.05). In comparison to pH(p=0.047), boron concentration(p<0.001) and Ca(OH)2 dosage(p<0.001) demonstrated a more pronounced impact on boron removal. The interaction between boron concentration and Ca(OH)2 dosage was also identified as statistically significant(p<0.001).Conclusion : Chemical precipitation using microwave heating was effective in removal of boron from wastewater, and the optimal conditions in continuous scale through response surface analysis were initial pH 3.3, boron concentration 1,500 mg/L, and Ca(OH)2 dosage 6.2 g(207 g/L).

Heterogeneous Catalytic Ozonation of Pharmaceuticals: Optimization of the Process by Response Surface Methodology.

Batch heterogeneous catalytic ozonation experiments were performed using commercial and synthesized nanoparticles as catalysts in aqueous ozone. The transferred ozone dose (TOD) ranged from 0 to 150 μM, and nanoparticles were added in concentrations between 0 and 1.5 g L-1, with all experiments conducted at 20 °C and a total volume of 240 mL. A Ce-doped TiO2 catalyst (1% molar ratio of Ce/Ti) was synthesized via the sol-gel method. Response surface methodology (RSM) was applied to identify the most significant factors affecting the removal of selected pharmaceuticals, with TOD emerging as the most critical variable. Higher TOD resulted in greater removal efficiencies. Furthermore, it was found that the commercially available metal oxides α-Al2O3, Mn2O3, TiO2, and CeO2, as well as the synthesized CeTiOx, did not increase the catalytic activity of ozone during the degradation of ibuprofen (IBF) and para-chlorobenzoic acid (pCBA). Carbamazepine (CBZ) and diclofenac (DCF) are compounds susceptible to ozone oxidation, thus their complete degradation at 150 μM transferred ozone dose was attained. The limited catalytic effect was attributed to the rapid consumption of ozone within the first minute of reaction, as well as the saturation of catalyst active sites by water molecules, which inhibited effective ozone adsorption and subsequent hydroxyl radical generation (●OH).

Pilot-scale bioremediation of rare earths wastewater by Chlamydomonas sp. YC

The extraction of rare earth elements (REEs) through in-situ leaching with ammonium sulphate [(NH4)2SO4] had resulted in the production of a large volume of ammonium-rich wastewater, causing severe environmental pollution. This study aimed to assess the ability of an indigenous microalga Chlamydomonas sp. YC, isolated from REEs wastewater, to directly treat real REEs wastewater under outdoor conditions in 50 L airlift photobioreactors (AL-PBRs) and 5.0 m3 open race-way photobioreactors (ORWPs). Additionally, the harvested Chlamydomonas sp. YC biomasses from these two pilot photobioreactors were comprehensively analyzed to evaluate the nutritional values. The results showed that Chlamydomonas sp. YC in AL-PBRs exhibited higher biomass production (1.1 g/L), greater removal efficiencies in NH4+-N (24.9%) and total nitrogen (20.4%), as well as higher CO2 fixation rate (125.0 mg/(L·d)), compared to those of ORWPs. Moreover, the Chlamydomonas sp. YC biomasses obtained from the two pilot photobioreactors contained 44.5% and 49.4% protein, 9.1% and 14.3% lipids. Moreover, Chlamydomonas sp. YC in the two pilot photobioreactors displayed essential amino acid indexes (EAAI) of 0.900, which was higher than that of soybean protein (0.657), indicating superior nutritional values. In conclusion, the implementation of the process involving Chlamydomonas sp. YC in AL-PBRs under outdoor conditions holds promise as a coupled microalgal biotechnology for the simultaneous removal of NH4+-N from REEs wastewater, and the capture of CO2 for the production of valuable biomass.

Remediation of Heavy Metal Pollution from Coal Mine Effluent Using Metal-Organic Frameworks (MOF): Impact of Water Media, Operational Factors and Metal Characteristics

The energy sector is the sector that generates the highest amount of environmental contamination, especially in water sources, mostly in the case of coal-based energy production. The aim of this study was to examine a significant contamination source, heavy metal contamination, in coal mining effluents. The current investigation introduces an MOF platform based on zirconium clusters and isophthalic acid with NH2-MIP-SO3H mixed amine and sulfonic acid functional groups in order to remove the most common heavy metal ions in coal mining effluents, including Hg, Cd, Pb, and Cu ions. The water matrix and the operational conditions were identified to be very influential in the removal process, such as the pH of water, the initial metal concentration and operating time. NH2-MIP-SO3H offers a great removal efficiency of metals starting from 745.83 mg/g for Cd, 673.67 mg/g for Cu, 589.85 mg/g for Hg, and 481.66 mg/g for Pb ions, with the Langmuir equation for equilibrium and pseudo-second-order equation for kinetics being the ideal models to express the equilibrium and kinetic data, respectively. A significant impact of water pH was found to occur, with the NH2-MIP-SO3H platform performing best at pH 6. Reuse of NH2-MIP-SO3H demonstrates excellent reusability, sustaining 90% of initial performance over eight regeneration cycles. The interaction of functional group-functional metal was the dominant mechanism in the removal process. The NH2-MIP-SO3H unique approach to heavy metal removal provides a very hopeful outlook for additional investigations in larger-scale studies.

Study on the operation effect of old and new process replacement based on denitrification deep bed filters

In order to study the effect of replacing old and new processes in denitrifying deep-bed filter, the water quality data before and after equipment upgrading at the same period were collected for comparative analysis. The results show that the new process has a desirable removal rates for COD (93.67%), BOD (96.82%), NH3-N (98.04%) and SS (97.47%) throughout the year, respectively, with the effective and feasible denitrification process. The average TN concentration in effluent was 6.1mg/L after process upgrading, which decreased by 41.69% compared with the same period before process upgrading. The average removal rate was 72.5%, which was much higher than that before replacement (58.8%). In general, the denitrification deep bed filter had a great nitrogen removal efficiency.

Facile synthesis of zeolite catalyst from lithium slag efficiently activates peroxymonosulfate for tetracycline degradation: •O2- and the electron transfer

Iron is the most suitable candidate for activating peroxymonosulfate (PMS) for organic degradation. To realize the effective separation and recycling of iron catalysts, it is urgent to explore a low-cost and excellent supporter. In this study, a zeolite catalyst (CAN) with both supporter and catalyst functions was synthesized in one step using lithium slag (LS, containing iron), and used to degrade tetracycline (TC) wastewater. The results showed that the electron transfer of iron and sulfur in CAN promotes the decomposition of PMS. The CAN/PMS system exhibited great removal efficiency (89.5 %, 0.083 min−1) and relatively lower activation energy (15.31 kJ/mol) toward TC. And •O2- plays a crucial role in the degradation. The CAN also represented great catalytic stability and reusability. This study revealed a new approach for the synthesis of high efficiency and low-cost catalysts and the tetracycline degradation.

A sustainable and highly efficient photocatalytic and supercapacitor electrode for biogenic nickel oxide nanoparticle infused graphene oxide

Energy-storage device manufacturing focuses on cost-effective, efficient, and stable solutions. Electrodes based on graphene oxide (GO) and nickel oxide (NiO) have enhanced electrochemical characteristics, such as high specific capacitance and prolonged cycle stability, which are desirable in supercapacitors. Moreover, a green synthesis pathway was developed for the production of NiO/graphene oxide composites (GO-NiO). FESEM, HRTEM, FTIR, XRD, XPS, UV–Vis, and Raman spectroscopy were among the many methods used to characterize the as-prepared nanocomposites. Since both NiO and the GO-NiO nanocomposite displayed estimated optical band gaps of about 3.45 eV, they were regarded to be semiconductors with potential applications as photocatalysts. GO-NiO nanocomposite was used to adsorb and photodegrade Acridine orange (AO) and Rhodamine-B (Rh-B) from an aqueous solution. In the presence of visible light, the GO-NiO nanocomposite undergoes photodegradation and adsorption at a much quicker rate and with a greater removal efficiency than when exposed to darkness. In under 90 min, GO-NiO composite removed 86.81% of Acridine orange and 86.12% of Rhodamine-B. Photodegradation and adsorption in visible light remove Acridine orange and Rhodamine-B more effectively than adsorption alone. Electrochemical studies of GO-NiO nanocomposites showed that the samples are very stable over numerous cycles and have a specific capacitance of about 228.78 Fg−1 at a scan rate of 10 mV s−1. The NiO-infused GO nanocomposites for photocatalytic and supercapacitor applications are new because of their synergistic features, which efficiently degrade pollutants and store energy, with extensive environmental and energy applications.

Multivariate optimization of organic matter and color removal from textile dyeing industry wastewater by ultraviolet-activated oxidants

This study investigated the efficiency of ultraviolet (UV) activation of the oxidants that are used in advanced oxidation processes in textile dyeing industry wastewater treatment with high concentrations of refractory organic matter and strong color. The effect of peroxymonosulfate (PMS), peroxydisulfate (PS), hydrogen peroxide (HP), percarbonate (PC), and chlorine as oxidants in UV-based processes was first evaluated. The two processes with the greatest removal efficiency were determined as UV/PS and UV/PMS. Then the operating parameters for UV/PS and UV/PMS were optimized by the Box-Behnken Design (BBD). Process parameters for both processes were oxidant dosage, initial pH, and reaction time whereas system responses were chemical oxygen demand (COD), UV254, and color removal efficiency. Under optimum conditions in the UV/PS process (pH 5.54, PS dosage 24.4 mM, and reaction time 117 min), COD, UV254, and color removal efficiency were 83.21 %, 92.14 %, and 93.87 %, respectively. Under optimum conditions in the UV/PMS process (pH 5.83, PMS dosage 23.1 mM, and reaction time 120 min), COD, UV254, and color removal efficiency were 66.89 %, 78.45 %, and 96.89 %, respectively. The R2 of all the models that applied for the system responses of both processes was nearly one and the adj R2 values were very near to the R2 values. These findings showed that the BBD is efficient, suitable, and significant in modeling the removal of pollutants in textile dyeing industry wastewater by UV/PS and UV/PMS processes. Electrical Energy per Order (EE/O) calculations for UV/PS and UV/PMS processes were 101 and 167 kWh/m3 for optimum conditions, respectively. The results showed that both UV/PS and UV/PMS processes are effective; however, the UV/PS process is more economical and effective concerning pollutant removal efficiency and EE/O calculations.

Effect of bank slope and ambient groundwater discharge on hyporheic transport and biogeochemical reactions in a compound channel

AbstractAs floodplains are inundated during floods in a compound channel, solutes in the surface water column reach the hyporheic zone and react with solutes upwelled from the groundwater. These biogeochemical reactive processes, such as aerobic respiration, nitrification, and denitrification, need more clarification. In this study, a 3D hydrodynamic model combined with a 2D groundwater and biogeochemical model was used to examine the influence of bank slope angle and ambient groundwater discharge on these processes. A denitrification zone was found under the interface between the main channel and the floodplain when the bank slope angle was 90°, while lower angles extended that zone horizontally. In addition, a lower bank angle decreased N entry into the streambed and enhanced nitrogen removal. A decrease in ambient groundwater had a negative impact on both aerobic respiration and denitrification. When the ambient groundwater discharge reached below −0.9 m/d, nitrification was dominant in the model domain, and the hyporheic zone turned into a NO3− source. The greatest removal efficiency, equal to 0.8, was attained at a discharge rate of −0.5 m/d for ambient groundwater and a bank slope angle of 30°. The hyporheic zone should lose its ability to remove N when ambient groundwater discharges exceed 0.25 m/d and removal efficiency fluctuates by 0. In conclusion, our findings indicate that bank slope angle and ambient groundwater discharge have a substantial impact on solute transport and biogeochemical activities in the hyporheic zone of a compound channel.

The Ce-Fe loaded biochar for efficient removal of hexavalent chromium: Broad pH adaptation and mechanisms

The adsorption as a convenient, effective and economical method has been widely used for the removal of highly toxic Cr(VI) from aqueous solution in recent years. However, the adsorption for Cr(VI) was usually more effective under acidic conditions and less effective in neutral and alkaline environments, and there are few studies on the response sequence of the functional groups on the biochar participating in the Cr(VI) removal process. The biochar CeFe-SPBC prepared in this work not only showed a great removal efficiency (85.7%) for Cr(VI) at pH= 3, but also exhibited a removal efficiency close to 70% for Cr(VI) at pH= 9, which reflected that the CeFe-SPBC had an excellent adaptability to changes in pH. The characterization results displayed the large specific surface area (296 m2/g) and various functional groups as well as metal oxides of CeFe-SPBC. And, the response sequence of the main functional groups was identified as follows: Ce-O > Fe-O > aromatic CC > C-OH > -COO-. On this basis, the adsorption-enhanced reduction-immobilization mechanisms of Cr(VI) on the surface of the CeFe-SPBC were discussed in detail.

One-step modification of MIL-88A(Fe) enhanced electro-Fenton coupled membrane filtration system for the removal of bisphenol A

An electro-Fenton coupled membrane filtration system (abbreviated as EF-MF system) was constructed for the efficient removal of bisphenol A (abbreviated as BPA, a kind of pharmaceuticals and personal care products, abbreviated as PPCPs). In the EF-MF system, a porous Fe3O4/FeO/Fe@C catalyst was synthesized and applied to enhance the electro-Fenton reaction, and polyvinylidene fluoride/carbon fiber cloth composite cathode membrane was used as both cathode electrode and membrane. Characterization results indicated the porous Fe3O4/FeO/Fe@C catalyst exhibited micron-level rod morphology and was in an encapsulated structure with Fe3O4/FeO/Fe composite nanoparticles covered by porous graphitic carbon. Degradation experiments indicated the EF-MF system exhibited great removal efficiency (approximately 96.97%) towards BPA within 70 min in the conditions of catalyst dosing at 0.500 g·L−1, the value of pH at 3 and the current density at 0.67 mA cm−2. Quenching experiments verified both OH radical and O2− radical played significant roles in the decomposition of BPA. The mass formation of reactive oxygen radicals was mostly owing to the easy access of H2O2 to the activated sites of the porous Fe3O4/FeO/Fe@C catalyst through the porous structure and the rapid cycle conversion between zero-valent iron (ZVI), Fe(Ⅱ) and Fe(Ⅲ). Based on the results of intermediates identification, three possible decomposition pathways were presented. Toxicity analysis exhibited most of the intermediates were in less toxicity than BPA. Moreover, the EF-MF system exhibited good stability after four-cyclic utilization. This work provides an efficient and energy-saving strategy for the removal of PPCPs.

Removal of oxytetracycline and sulfamethoxazole in vertical down-up flow constructed wetlands: Efficiency, removal pathways, and occurrence of antibiotic resistance genes

The extensive use of antibiotics leads to their frequent detection in the environment, posing potential threats to public health. Constructed wetlands (CWs) have been widely applied in wastewater treatment and can efficiently remove antibiotics. However, the removal of antibiotics in the CWs is still in a “black box”, and the information about the potential risks of antibiotic resistance genes (ARGs) occurrence in CWs is limited. In the present study, the removal of oxytetracycline (OTC) and sulfamethoxazole (SMZ), as well ARGs occurrence in vertical down-up flow constructed wetlands (VDUF-CWs) were assessed. The results indicated that VDUF-CWs exhibited great removal efficiency for OTC (84.3 ± 3.5 %) and SMZ (77.7 ± 3.9 %). Based on conservation of mass, the contributions of different removal pathways (i.e., microbial degradation, plant absorption, photodegradation, and substrate adsorption) to antibiotic removal were calculated. Of which, microbial degradation was found to be the dominant route in removing OTC and SMZ with the contribution of 58.52 ± 2.34 % and 65.13 ± 3.72 % respectively, followed by photodegradation (18.47 ± 3.04 % and 8.22 ± 3.94 %), plant absorption (9.01 ± 1.28 % and 7.75 ± 4.07 %) and substrate adsorption (2.08 ± 0.03 % and 1.73 ± 0.02 %). Notably, tetA, tetC, tetW, sulI, and sulII genes were detected in layer samples, and the relative abundances of the sul and tet genes were boosted with the extension of operation days, indicating that VDUF-CWs allow a risk of ARGs spread and threatening public health. The present study provided a deeper insight into the mechanism of antibiotic removal in CWs, but further explorations are required to develop the effective control strategies for eliminating ARGs from CWs.

Analysis of the Performance of Cover Soil in Attenuating the Physicochemical Parameters of Landfill Leachate by Soil Column Test

Landfill leachate is of environmental concern due to its high levels of organic and inorganic pollutants. Leachate treatment using natural materials such as cover soil of sandy loam texture, laterites, and compost was performed through soil column experiment. This study aims to analyze the natural attenuation of physiochemical parameters such as pH, turbidity, electrical conductivity, biological oxygen demand, chemical oxygen demand (COD), ammonia, phosphate, heavy metals (Fe, Ni, and Pb) of leachate in the cover soil of the Sisdole landfill site (SLS) and enhanced cover soil, that is, a mixture of SLS soil, compost, and laterite (SCL). In addition, this study analyzes the response of the cover soil after infiltration of leachate in terms of physiochemical parameters. Two columns of specific heights and diameters were taken and leachate was fed manually into the soil columns to evaluate the attenuation of the physiochemical parameters of leachate by standard methods after passing through SLS and SCL soil. From the results, it was observed that the removal efficiency was the highest for the first three days (>70%), after which the capacity of the soil to attenuate leachate parameters decreased. Consistent and greater removal efficiency was seen for heavy metals and phosphate for the SLS soil column. Amendments such as laterite and compost were added to cover soil to enhance the performance of SLS soil. The results showed a consistent and greater removal percentage for COD and ammonia in SCL than in SLS soil column. It was observed that that studied soil (sandy loam) is capable of removing pollutants from leachate to a satisfactory level and adding materials with higher sorption capacity such as laterite and compost to sandy loam soil can improve removal ability for certain selected parameters.

Smart bifunctional covalent organic frameworks for water treatment: Reversible colorimetric pH detection and photocatalytic removal of pollutants

Covalent Organic Frameworks (COFs) with uniform aperture size, high surface area and tunable structure have been proposed as a potential material in water treatment. In this work, we utilized methoxy based covalent organic frameworks (COF–OMe) at room temperature as a dual-role smart material. For one thing, it can respond to the pH of solutions by visual, colorimetric change. Due to the protonation effect of methoxy groups in its pore skeleton, the fluorescent intensity of COF–OMe went down and the color changed from yellow to black as the pH decreased reversibly. For another, the abundant pores and ordered conjugated structure endowed it with a large surface area and light absorption ability. Therefore, the light-triggered oxidase-mimic porous COF–OMe can be applied in the synergistic removal of organic pollutants with synergistic physical absorption and light degradation. The outstanding and sensitive response to pH, great removal efficiency and dual function made it applied in water treatment with great potential, achieving killing two birds with one stone.

Biotoxicity dynamic change and key toxic organics identification of coal chemical wastewater along a novel full-scale treatment process

It is particularly important to comprehensively assess the biotoxicity variation of industrial wastewater along the treatment process for ensuring the water environment security. However, intensive studies on the biotoxicity reduction of industrial wastewater are still limited. In this study, the toxic organics removal and biotoxicity reduction of coal chemical wastewater (CCW) along a novel full-scale treatment process based on the pretreatment process-anaerobic process-biological enhanced (BE) process-anoxic/oxic (A/O) process-advanced treatment process was evaluated. This process performed great removal efficiency of COD, total phenol, NH4+-N and total nitrogen. And the biotoxicity variation along the treatment units was analyzed from the perspective of acute biotoxicity, genotixicity and oxidative damage. The results indicated that the effluent of pretreatment process presented relatively high acute biotoxicity to Tetrahymena thermophila. But the acute biotoxicity was significantly reduced in BE-A/O process. And the genotoxicity and oxidative damage to Tetrahymena thermophila were significantly decreased after advanced treatment. The polar organics in CCW were identified as the main biotoxicity contributors. Phenols were positively correlated with acute biotoxicity, while the nitrogenous heterocyclic compounds and polycyclic aromatic hydrocarbons were positively correlated with genotoxicity. Although the biotoxicity was effectively reduced in the novel full-scale treatment process, the effluent still performed potential biotoxicity, which need to be further explored in order to reduce environmental risk.

Biochar Derived from Chinese Herb Medicine Residues for Rhodamine B Dye Adsorption.

In this study, one well-known CHM residue (Atropa belladonna L., ABL) was used to prepare biochar capable of adsorbing rhodamine B (RhB) with an ultrahigh surface area for the first time. Three micropore-rich ABL biochars including ABL@ZnCl2 (1866 m2/g), ABL@H3PO4 (1488 m2/g), and ABL@KOH (590 m2/g) were obtained using the one-step carbonization method with activation agents (ZnCl2, H3PO4, and KOH) via chemical activation and carbonization at 500 °C, and their adsorption performance for RhB was systematically studied with adsorption kinetics, isotherms, and thermodynamics. Through pore diffusion, π-π interaction, and hydrogen bonding, ABL biochar had excellent adsorption performance for RhB. Moreover, when C 0 was 200 mg/L, biochar dosage was 1 g/L, and the contact time was 120 min; the maximum RhB adsorption capacity and removal efficiency on ABL@ZnCl2 and ABL@H3PO4 were 190.63 mg/g, 95% and 184.70 mg/g, 92%, respectively, indicating that it was feasible to prepare biochar from the ABL residue for RhB adsorption. The theoretical maximum adsorption capacities of ABL@ZnCl2 and ABL@H3PO4 for RhB were 263.19 mg/g and 309.11 mg/g at 25 °C, respectively. Furthermore, the prepared biochar showed good economic applicability, with pay back of USD 972/t (ABL@ZnCl2) and USD 987/t (ABL@H3PO4), respectively. More importantly, even after five cycles, ABL@H3PO4 biochar still showed great RhB removal efficiency, suggesting that it had a good application prospect and provided a new method for the resource utilization of traditional CHM residues. Additionally, pore diffusion, π-π interactions, and hydrogen bonding all play roles in the physical adsorption of RhB on ABL biochar. π-π interactions dominated in the early stage of RhB adsorption on ABL@H3PO4, while pore diffusion played a crucial role in the whole adsorption process on both adsorbents.

An ionic vinylene-linked three-dimensional covalent organic framework for selective and efficient trapping of ReO4- or 99TcO4.

The synthesis of ionic olefin linked three-dimensional covalent organic frameworks (3D COFs) is greatly challenging given the hardness of the formation of stable carbon-carbon double bonds (-C = C-). Herein, we report a general strategy for designing porous positively charged sp2 carbon-linked 3D COFs through the Aldol condensation promoted by quaternization. The obtained 3D COFs, namely TFPM-PZI and TAPM-PZI, showed impressive chemical stability. Furthermore, the positively charged frameworks with regular porosity endow 3D ionic COFs with selective capture radioactive ReO4-/TcO4- and great removal efficiency in simulated Hanford waste. This research not only broadens the category of 3D COFs but also promotes the application of COFs as efficient functional materials.

Removal of pharmaceutical contaminants through membrane bioreactor

One of the most basic life needs is water, being utilized in our consistent daily needs for example; drinking, washing, cooking, and so forth. The rapid growth of the population and economy around the world gives rise to the demand for sanitary water. Water is polluted by industry, residential, and agricultural waste streams. Pharmaceutical contaminants have been emerging in water bodies with different types of groups. This contaminant can be treated by conventional techniques such as; chlorination, activated carbon, etc. A membrane bioreactor is a combination of a membrane process like ultra-filtration or Nano-filtration with an activated sludge process. It can be equipped with external devices such as an external loop airlift membrane has proven to remove 100 % of acetaminophen within 24 h. It can also be equipped with reverse osmosis and nano-filtration membrane where it has proven to remove around 20 and 13 contaminants respectively with > 90 % removal efficiency. In addition, increasing some factors such as sludge retention time has shown significant removal efficiency while enhancing the performance of the bioreactor. The advantage of MBR over conventional treatment techniques is that it has greater removal efficiency, a small footprint, better process control, and low sludge production. This article reviews some methods used to remove pharmaceutical contaminants from wastewater using a membrane bioreactor.

Preparation of ethylenediamine-modified pectin/alginate/Fe3O4 microsphere and its efficient Pb2+ adsorption properties

As a common macromolecular carbohydrate, pectin has a strong affinity for Pb2+. An ethylenediamine modified pectin (EP48) with 48 % of amidation was prepared and exhibited great removal efficiency towards Pb2+ in our previous study. However, the EP48 has drawbacks in adsorption including low mechanical strength and difficulty in separation. In this study, EP48 was compounded with sodium alginate (Alg) and Fe3O4 to synthesize EP48/Alg/Fe3O4 microsphere. The physicochemical properties and Pb2+ adsorption characteristics of microsphere were analyzed. It was found that the microsphere exhibited good thermal stability, mechanical strength, porous structure, as well as acid tolerance. The pseudo-second-order model well described the kinetics of adsorption process, indicating the chemical adsorption is dominant. The Langmuir model fitted the experimental data well, and the maximum adsorption capacity reached 175.19 mg/g. Adsorption-desorption experiments showed that the removal rate of the microsphere maintained over 98.9 % after 10 cycles. The X-ray photoelectron spectroscopy (XPS) analyses revealed that the potential adsorption mechanism included ion-exchange and chelation. The above results suggested its potential use for the removal of Pb2+ from wastewater.

Evaluation of the lipase from castor bean (Ricinus Communis L.) as a potential agent for the remediation of used lubricating oil contaminated soils.

Bioremediation of hydrocarbons-contaminated soils, using enzymes, is considered an alternative technology for soil remediation, obtaining shorter remediation times, greater removal efficiencies, and less waste generation. The lipases from invasive plants such as castor bean (Ricinus Communis L.) could represent an opportunity for its application in this purpose. This paper reports the results of evaluating enzymatic treatment at different conditions for the remediation of used lubricating oil-contaminated soils. Four assays were performed for the removal of the contaminant in a soil sample: (1) natural attenuation and (2) biostimulation with urea (10% w/v), both used as blanks, (3) enzymatic treatment with lipases at ambient conditions (room temperature, soil pH) and (4) enzymatic treatment with lipases at ideal conditions (temperature 37°C, pH 4.5). After seven weeks of treatment, removal percentages of 14.23 ± 1.92%, 35.71 ± 5.17%, 14.11 ± 6.71%, and 94.26 ± 1.91%, respectively, were obtained. The degradation of the contaminant was analyzed by Fourier-transform Infrared spectroscopy (FTIR) for each assay. Results show the potential of the lipases for catalyzing the degradation of this contaminant in the soil at ideal conditions, representing an alternative technology to be applied as treatment ex-situ. This paper is the first study known to show the utilization of castor bean lipase for the remediation of hydrocarbons-contaminated soils.