Efficiency studies of modified IFAS-OSA system upgraded by an anoxic sludge holding tank.

An upgraded integrated fixed-film activated sludge-oxic settling anoxic (IFAS-OSA) system is a new technology for reducing nutrients and excess sludge. The results showed that the average TN removal efficiency of the IFAS-OSA system was gradually increased up to 7.5%, while the PO-P removal efficiency increased up-to 27%, compared with that of the IFAS system.

Role of carrier characteristics affecting microbial density and population in enhanced nitrogen and phosphorus removal from wastewater.

This research aims to improve simultaneous nitrification-denitrification and phosphorus removal (SNDPR) using novel carriers and to demonstrate the effect of carrier characteristics on nutrient removal in a biofilm reactor. For this purpose, biofilms enriched with both polyphosphate-accumulating organisms (PAOs) and nitrifiers were cultivated in two parallel sequencing batch reactors containing conventional moving bed bioreactor carriers (MBBR) and a novel type of carriers (carbon-based moving carriers (CBMC)). The new carriers were produced based on recycled waste materials via a chemical-thermal process and their specific surface area were 10.

Pharmaceuticals removal by immobilized laccase on polyvinylidene fluoride nanocomposite with multi-walled carbon nanotubes.

The presence of pharmaceutical micropollutants in water and wastewater is considered a serious environmental issue. To eliminate these pollutants, biodegradation of pharmaceuticals using enzymes such as laccase, is proposed as a green method. In this study, immobilized laccase was used for the removal of two model pharmaceutical compounds, carbamazepine and diclofenac.

Orthodontists' preference on type of rigid fixed functional appliance for skeletal Class II correction: A survey study.

Background: Rigid fixed functional appliances are most commonly used to correct skeletal Class II malocclusions. The objective of this study was to assess orthodontists' preference of different rigid fixed functional appliances used in the U.S.

Removal of bisphenol A in aqueous solution using magnetic cross-linked laccase aggregates from Trametes hirsuta.

Enzymatic removal of Bisphenol A (BPA), acknowledged as an environmentally friendly approach, is a promising method to deal with hard degradable contaminants. However, the application of "enzymatic treatment" has been limited due to lower operational stability and practical difficulties associated with recovery and recycling. Enzyme immobilization is an innovative approach which circumvents these drawbacks.

Enhancement of biological nitrogen removal performance using novel carriers based on the recycling of waste materials.

This study aims to enhance biological nitrogen removal performance by the innovative carbon-based carriers. The new carriers were produced based on recycling waste materials. In these carriers, the advantages of the hybrid system and physicochemical properties of activated carbon were integrated to promote microbial attachment.

Laser irradiation for controlling size of TiO-Zeolite nanocomposite in removal of 2,4-dichlorophenoxyacetic acid herbicide.

This study focused on the synthesis of TiO-Zeolite nanocomposite through a sol-gel approach. The decrease in the size of the nanocomposite is considered a primary parameter to improve photocatalytic activity. In this regard, fabricated samples were exposed to laser irradiation (532 nm) for four different time intervals in order to investigate the size variation of the nanocomposite.

Developing a new approach for (biological) optimal control problems: Application to optimization of laccase production with a comparison between response surface methodology and novel geometric procedure.

Laccase production by indigenous fungus, Phanerochaete chrysosporium, requires solving optimal problems to determine the maximum production of the enzyme within a definite time period and conditions specified in the solid-state fermentation process. For this purpose, parallel to response surface methodology, an analytical approach has been proposed based on the advanced concepts of Poisson geometry and Lie groups, which lead to a system of the Hamiltonian equations. Despite the dating of the Hamiltonian approach to solving biological problems, the novelty of this paper is based on the expression of a Hamiltonian system in notions of Poisson geometry, Lie algebras and symmetry groups and first integrals.

Application of ZnO-Ag-Nd nanocomposite as a new synthesized nanophotocatalyst for the degradation of organic compounds: kinetic, thermodynamic and economic study.

In the present research, a zinc oxide (ZnO)-silver (Ag)-neodymium (Nd) nanocomposite was synthesized via the combustion method for the degradation of dyes as organic pollutants. The synthesized nanophotocatalyst was characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques. The process of organic pollutant (Acid Red 18) removal was carried out in a semi-batch photoreactor equipped with an ultraviolet lamp.

The use of halophytic plants for salt phytoremediation in constructed wetlands.

This research studied the use of constructed wetlands (CWs) to reduce water salinity. For this purpose, three halophytic species of the Chenopodiaceae family (Salicornia europaea, Salsola crassa, and Bienertia cycloptera) that are resistant to saline conditions were planted in the CWs, and experiments were conducted at three different salinity levels [electrical conductivity (EC)∼2, 6, 10 dS/m]. EC and concentrations of calcium (Ca), magnesium (Mg), sodium (Na), and chlorine (Cl) were measured before and after phytoremediation with a retention time of 1 week.

The highest inhibition coefficient of phenol biodegradation using an acclimated mixed culture.

In this study a membrane biological reactor (MBR) was operated at 25 ± 1 °C and pH = 7.5 ± 0.5 to treat synthetic wastewater containing high phenol concentrations.

Nitrogen removal from high organic loading wastewater in modified Ludzack-Ettinger configuration MBBR system.

A moving bed biofilm reactor with pre-denitrification configuration was fed with a synthetic wastewater containing high chemical oxygen demand (COD) and ammonia. By changing different variables including ammonium and COD loading, nitrification rate in the aerobic reactor and denitrification rate in the anoxic reactor were monitored. Changing the influent loading was achieved via adjusting the inlet COD (956-2,096 mg/L), inlet ammonium (183-438 mg/L), and hydraulic retention time of the aerobic reactor (8, 12, and 18 hours).

Application of chitosan-citric acid nanoparticles for removal of chromium (VI).

In the present study, CS-CA nanoparticle was prepared for forming a new amide linkage, by grafting the amino groups of CS in the presence of carboxylic groups of CA that acts as cross-linking agent. The as-prepared CS-CA nanoparticle samples were characterized by use of dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques, which showed that the cross-linking agent preserved during the chemical modifications. The adsorption capacity of the CS-CA nanoparticles for the removal of Cr (VI) in aqueous solution was studied.

Biological removal of phenol from saline wastewater using a moving bed biofilm reactor containing acclimated mixed consortia.

In this study, the performance of an aerobic moving bed biofilm reactor (MBBR) was assessed for the removal of phenol as the sole substrate from saline wastewater. The effect of several parameters namely inlet phenol concentration (200-1200 mg/L), hydraulic retention time (8-24 h), inlet salt content (10-70 g/L), phenol shock loading, hydraulic shock loading and salt shock loading on the performance of the 10 L MBBR inoculated with a mixed culture of active biomass gradually acclimated to phenol and salt were evaluated in terms of phenol and chemical oxygen demand (COD) removal efficiencies. The results indicated that phenol and COD removal efficiencies are affected by HRT, phenol and salt concentration in the bioreactor saline feed.

Utilization of moving bed biofilm reactor for industrial wastewater treatment containing ethylene glycol: kinetic and performance study.

One of the requirements for environmental engineering, which is currently being considered, is the removal of ethylene glycol (EG) as a hazardous environmental pollutant from industrial wastewater. Therefore, in a recent study, a moving bed biofilm reactor (MBBR) was applied at pilot scale to treat industrial effluents containing different concentrations of EG (600, 800, 1200, and 1800 mg L-1 ). The removal efficiency and kinetic analysis of the system were examined at different hydraulic retention times of 6, 8, 10, and 12 h as well as influent chemical oxygen demand (COD) ranged between values of 1000 and 3000mg L-1.

Efficient biodegradation of naphthalene by a newly characterized indigenous Achromobacter sp. FBHYA2 isolated from Tehran Oil Refinery Complex.

A bacterial strain, FBHYA2, capable of degrading naphthalene, was isolated from the American Petroleum Institute (API) separator of the Tehran Oil Refinery Complex (TORC). Strain FBHYA2 was identified as Achromobacter sp. based on physiological and biochemical characteristics and also phylogenetic similarity of 16S rRNA gene sequence.

Removal of chromium from aqueous solution using polyaniline--poly ethylene glycol composite.

The adsorption of chromium compounds from solutions by a composite of polyaniline/poly ethylene glycol (PANi/PEG) was investigated in this study. Experiments were conducted in batch mode under various operational conditions including agitation time, solution pH, PANi/PEG dose and initial concentration of chromium salts. Results showed that concentration of PEG at synthesizing stage has a significant effect on the capacity of produced composite for removal of chromium.

Kinetics of organic removal in fixed-bed aerobic biological reactor.

The process kinetics of a lab-scale upflow aerobic immobilized biomass (UAIB) reactor using simulated sugar-manufacturing wastewater as feed was investigated. The experimental unit consisted of a 22l reactor filled with high porosity pumice stone. The UAIB reactor was tested under different organic loads and different hydraulic retention times (HRT) and the substrate loading removal rate was compared with prediction of Stover-Kincannon model, second-order model and the first order substrate removal model.

Transnasal endoscopic resection of juvenile nasopharyngeal angiofibroma without preoperative embolization.

Juvenile nasopharyngeal angiofibroma (JNA) is a benign, highly vascular, and locally invasive tumor. Because the location of these tumors makes conventional surgery difficult, interest in endoscopic resection is increasing, particularly for the treatment of lesions that do not extend laterally into the infratemporal fossa. We report the results of our series of 23 patients with JNA (stage IIB or lower) who underwent transnasal endoscopic resection under hypotensive general anesthesia without preoperative embolization of the tumor All tumors were successfully excised.