Purification of Dye-stuff Contained Wastewater by a Hybrid Adsorption-Periphyton Reactor (HAPR): Performance and Mechanisms.
ABSTRACT: The aim of this study was to develop an environmental-benign bio-measure that could be used to purify dye-contaminated wastewater. Herein, a hybrid adsorption-periphyton reactor (HAPR), combining a bioadsorbent based adsorption unit and a periphyton-based photo-bioreactor (PPBR), was built and applied for the first time. Firstly, an efficient bioadsorbent, i.e, microwave-activated swede rape hull (MSRH), was produced, characterized and applied in an adsorption column, to pretreat methylene blue (MB) wastewater with high concentration (~100?mg?L-1 or higher). Thereafter, the effluent of adsorption column, with lower dye concentration (~0.5?mg?L-1), was collected and further purified by PPBR. Results showed that dye removal efficiency by HAPR was 99.95% (from 200?mg?L-1 to 0.1?mg?L-1 or lower). Decolorization mechanisms by PPBR, included adsorption process by extracellular polymeric substances (EPS) on the surface of periphyton and degradation process. The study showed that HAPR was a novel, environmental friendly, efficient and promising dye-purification method and deserved further attention in future investigation.
Project description:Periphyton is a complex mixture of algae, microbes, inorganic sediment, and organic matter that is attached to submerged surfaces in most flowing freshwater systems. This natural community is known to absorb pollutants from the water column, resulting in improved water quality. However, the role of periphyton in the fate and transport of genetic fecal markers suspended in the water column remains unclear. As application of genetic-based methodologies continues to increase in freshwater settings, it is important to identify any interactions that could potentially confound water quality interpretations. A 16 week indoor mesocosm study was conducted to simultaneously measure genetic fecal markers in the water column and in the associated periphyton when subject to wastewater source loading. Treated wastewater effluent was pumped directly from a treatment facility adjacent to the experimental stream facility. Inflow and outflow surface water grabs were paired with the collection of periphyton samples taken from the mesocosm substrates on a weekly basis. Samples were analyzed with three genetic fecal indicator quantitative real-time polymerase chain reaction assays targeting <i>Escherichia coli</i> (EC23S857), enterococci (Entero1), and <i>Bacteroidales</i> (GenBac3), as well as, two human host-associated fecal pollution markers (HF183 and HumM2). In addition, periphyton dry mass was measured. During wastewater effluent loading, genetic markers were detected in periphyton at frequencies up to 100% (EC23S857, Entero1, and GenBac3), 59.4% (HF183), and 21.9% (HumM2) confirming sequestration from the water column. Mean net-flux shifts in water column inflow and outflow genetic indicator concentrations further supported interactions between the periphyton and water column. In addition, positive correlations were observed between periphyton dry mass and genetic marker concentrations ranging from <i>r</i> = 0.693 (Entero1) to <i>r</i> = 0.911 (GenBac3). Overall, findings support the notion that genetic markers suspended in the water column can be trapped by periphyton, further suggesting that the benthic environment in flowing freshwater systems may be an important factor to consider for water quality management with molecular methods.
Project description:The biomass of Aspergillus flavus was modified by calcium chloride to achieve a bioadsorbent for treating nickel, cobalt, and zinc ions from aqueous solutions. The information of pH, bioadsorbent dose, contact time, and temperature effect on the removal efficiency are presented. The data of Freundlich and Langmuir isotherm and pseudo-first-order and pseudo-second-order kinetic models are also depicted. The data showed that the maximum bioadsorption capacity of nickel, cobalt, and zinc ions is 32.26, 31.06 and 27.86 mg/g, respectively. The suitability of the bioadsorbent in heavy metals removal at field condition was tested with a real wastewater sample collected from a plating plant in the final part of this dataset. Based on the findings, the bioadsorbent was shown to be an affordable alternative for the removal of metals in the wastewater.
Project description:Periphyton is an effective matrix for the removal of pollutants in wastewater and has been considered a promising method of bioremediation. However, it still needs to be verified whether periphyton can maintain microbial activity and pollutant removal efficiency when dealing with the influence with complex components, and the underlying mechanisms of periphyton need to be revealed further. Herein, this study investigated the microbial growth, activity and functional responses of periphyton after removal of Cu from wastewater. Results showed that the cultivated periphyton was dominated by filamentous algae, and high Cu removal efficiencies by periphyton were obtained after 108 h treatments. Although 2 mg/L Cu2+ changed the microalgal growth (decreasing the contents of total chlorophyll-a (Chla), the carbon source utilization and microbial metabolic activity in periphyton were not significantly affected and even increased by 2 mg/L Cu2+. Moreover, chemical oxygen demand (COD) removal rates were sustained after 0.5 and 2 mg/L Cu2+ treatments. Our work showed that periphyton had strong tolerance and resistance on Cu stress and is environmentally friendly in dealing with wastewater containing heavy metals, as the microbial functions in pollutant removal could be maintained.
Project description:This work reports the synthesis of nanosilica-coated magnetic carbonaceous adsorbents (MCA@SiO2) using low-temperature hydrothermal carbonization technique (HCT) and the feasibility to utilize it for methylene blue (MB) adsorption. Initially, a carbon precursor (CP) was synthesized from corn starch under saline conditions at 453 K via HCT followed by the magnetization of CP again via HCT at 453 K. Subsequently, MCA was coated with silica nanoparticles. MCA and MCA@SiO2 were characterized using X-ray diffraction, Fourier transform infrared, scanning electron microscopy/energy-dispersive spectroscopy, transmission electron microscopy, and Brunauer-Emmett-Teller (BET) N2 adsorption-desorption isotherms. The BET surface area of MCA and MCA@SiO2 were found to be 118 and 276 m2 g-1, respectively. Adsorption of MB onto MCA@SiO2 was performed using batch adsorption studies and in the optimum condition, MCA@SiO2 showed 99% adsorption efficiency with 0.5 g L-1 of MCA@SiO2 at pH 7. Adsorption isotherm studies predicted that MB adsorption onto MCA@SiO2 was homogeneous monolayer adsorption, which was best described using a Langmuir model with the maximum adsorption capacity of 516.9 mg g-1 at 25 °C. During adsorption kinetics, a rapid dye removal was observed which followed pseudo-first- as well as pseudo-second-order models, which suggested that MB dye molecules were adsorbed onto MCA@SiO2 via both ion exchange as well as the chemisorption process. The endothermic and spontaneous nature of the adsorption of MB onto MCA@SiO2 was established by thermodynamics studies. Mechanism of dye diffusion was collectively governed by intraparticle diffusion and film diffusion processes. Furthermore, MB was also selectively adsorbed from its mixture with an anionic dye, that is, methyl orange. Column adsorption studies showed that approximately 500 mL of MB having 50 mg L-1 concentration can be treated with 0.5 g L-1 of MCA@SiO2. Furthermore, MCA@SiO2 was repeatedly used for 20 cycles of adsorption-desorption of MB. Therefore, MCA@SiO2 can be effectively utilized in cationic dye-contaminated wastewater remediation applications.
Project description:Dyes in water change the colour, taste and odour of water, are highly visible, and can be toxic and cancerous for the coloured water consumption human beings. Basic dyes particularly, methylene blue, MB has high colour intensity, shows intense colour even at low concentration, and are very toxic due to their complex structure. Instead of adsorption, removal of MB from water using various traditional treatment methods is costly and less effective. The use of bioadsorbent provides easy and low cost technique for removal of MB. For searching the adequate technique of dye removal, adsorption efficiency and mechanism of bioadsorbent can be analyzed. To this, MB removal efficiency of seeds of medicinal plant, black cumin seeds were analyzed. The data are supplied in the article.
Project description:Proper remediation of aquatic environments contaminated by toxic organic dyes has become a research focus globally for environmental and chemical engineers. This study evaluates the adsorption potential of a polymer-based adsorbent, thiourea-modified poly(acrylonitrile-co-acrylic acid) (T-PAA) adsorbent, for the simultaneous uptake of malachite green (MG) and methylene blue (MB) dye ions from binary system in a continuous flow adsorption column. The influence of inlet dye concentrations, pH, flow rate, and adsorbent bed depth on adsorption process were investigated, and the breakthrough curves obtained experimentally. Results revealed that the sorption capacity of the T-PAA for MG and MB increase at high pH, concentration and bed-depth. Thomas, Bohart-Adams, and Yoon-Nelson models constants were calculated to describe MG and MB adsorption. It was found that the three dynamic models perfectly simulate the adsorption rate and behavior of cationic dyes entrapment. Finally, T-PAA adsorbent demonstrated good cyclic stability. It can be regenerated seven times (or cycles) with no significant loss in adsorption potential. Overall, the excellent sorption capacity and multiple usage make T-PAA polymer an attractive adsorbent materials for treatment of multicomponent dye bearing effluent in a fixed-bed column system.
Project description:Low cost fabrication of water treatment polymer materials directly from biomass resources is urgently needed in recent days. Herein, a compressive alginate sponge (AS) is prepared from seaweed biomass resources through a green two-step lyophilization method. This material is much different from conventional oven-, air-, vacuum-dried alginate-based adsorbents, which show limitations of shrinkage, rigidness, tight nonporous structure and restricted ions diffusion, hindering its practical applications, and was used to efficiently remove methylene blue (MB), a main colorful contaminant in dye manufacturing, from wastewater. The batch adsorption studies are carried out to determine the impact of pH, contact time and concentration of dye on the adsorption process. The maximum adsorption capacity can be obtained at 1279 mg g-1, and the shape-moldable AS can be facilely utilized as a fixed-bed absorption column, providing an efficient approach for continuous removal of MB within a short time. It is also important that such a compressive AS can be regenerated by a simple squeezing method while retaining about 70% capacity for more than ten cycles, which is convenient to be reused in practical water treatment. Compressive AS demonstrates its merits of high capability, large efficiency and easy to recycle as well as low cost resources, indicating widespread potentials for application in dye contaminant control regarding environmental protection.
Project description:Advances in nanoscale science and engineering are providing new opportunities to develop promising adsorbents for environmental remediation. Here, hybrid aerogels are assembled from cellulose nanofibrils (CNFs) and carbon nanomaterials to remove cationic dye methylene blue (MB) and anionic dye Congo red (CR) in single and binary systems. Two classes of carbon nanomaterials, carbon nanotubes (CNTs) and graphene nanoplates (GnPs), are incorporated into CNFs with various amounts, respectively. The adsorption, mechanics and structure properties of the hybrid aerogels are investigated and compared among different combinations. The results demonstrate CNF-GnP 3:1 hybrid exhibits the best performance among all composites. Regarding a single dye system, both dye adsorptions follow a pseudo-second-order adsorption kinetic and monolayer Langmuir adsorption isotherm. The maximal adsorption capacities of CNF-GnP aerogels for MB and CR are 1178.5 mg g-1 and 585.3 mg g-1, respectively. CNF-GnP hybrid show a superior binary dye adsorption capacity than pristine CNF or GnP. Furthermore, nearly 80% of MB or CR can be desorbed from CNF-GNP using ethanol as the desorption agent, indicating the reusability of this hybrid material. Hence, the CNF-GnP aerogels show great promise as adsorption materials for wastewater treatment.
Project description:A novel hydrophobic and cationic cyclodextrin-based acrylamide flocculant (AM-?-CD-DMDAAC) was prepared by chemical oxidative polymerization to adsorb water-soluble dyes in dye wastewater. Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope and thermogravimetric (TG) measurements results demonstrated that the AM-?-CD-DMDAAC was successfully synthesized. The effects of pH, contact time, initial dye concentration, temperature and adsorbent dose on dye removal efficiency for AM-?-CD-DMDAAC flocculants were investigated. The kinetic data were found to follow the pseudo-second-order kinetic model. The equilibrium adsorption data were fitted to the Langmuir isotherm model, with the maximum adsorption capacity of 147.1 mg g-1. The adsorbent retained about 60% of the adsorption efficiency after three adsorption/desorption cycles, which implied a promising application as the dye adsorbent.
Project description:The treatment of wastewater always demands eco-friendly and cost-efficient adsorbents. In this paper, spent mushroom waste (SMW) was modified by a cationic surfactant (cetyltrimethylammonium bromide, CTAB) to eliminate toxic dyes. A characterization of adsorbents confirmed that CTAB was successfully embedded into the SMW structure. The spent mushroom waste, modified by CTAB (SMWC), exhibited an excellent adsorption capacity of 249.57 mg·g−1, 338.67 mg·g−1, and 265.01 mg·g−1 for the Direct red 5B (DR5B), Direct blue 71 (DB71), and Reactive black (RB5) dyes, respectively. Batch experiments indicated that the dye adsorption of SMWC depended mainly on pH, dye concentration, temperature, and ionic strength. The adsorption isotherm could be fitted to the Langmuir model and described by the pseudo-second-order kinetic model. The dye adsorption mechanism was dominated mostly by the chemosorption of the dyes and the SMWC surface. Thermodynamic parameters showed that the adsorption was endothermic and spontaneous. SMWC could successfully remove over 90% of dyes from various water samples. This can be considered a feasible waste resource utility, since it meets both the ecological and the economic requirements for auspicious industrial applications.