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In this study, amino functionalized cellulose nanocrystals–polyethersulfone nanocomposite membrane (A-CNC/PES) based on agricultural waste was used for the removal of diazinon (DZ) from aqueous solution. The fabricated membrane has been characterized via attenuated total reflectance-Fourier transform infrared (ATR-FTIR), scanning electron microscopy (SEM), dispersive X-ray spectrometer (EDX), X-ray diffractometer (XRD), thermal gravimetric analysis (TGA), water contact angel (WCA), porosity, and mean pore radius. The effect of variables, such as initial DZ concentration, pH, and A-CNC content, on the membrane performance was optimized using response surface methodology (RSM) through central composite design (CCD). The results indicated that the additive had the most significant effect on the hydrophilicity improvement, reducing surface roughness, and reducing fouling. The highest removal efficiency of A-CNC/PES membrane for DZ was about 99.3% (at A-CNC: 0.2 wt%), and more than three-fold water flux improvement (27.3 versus 8.3 kg/m2.h for unmodified membrane) was attained. The results of antifouling test confirmed that the A-CNC/PES membranes had a high-flux recovery (FRR: 90.05%). This study may provide promising insights for the development of next generation of agricultural waste-based nanocomposite membrane in the water and wastewater treatment. Highly efficient removal of diazinon pesticide from aqueous solutions by using grape branch-derived CNCs-PES nanocomposite membrane. [ABSTRACT FROM AUTHOR]

Soft drinks are industrial intermediate chemicals found in wastewater and are among the most significant environmental pollutants. Up-flow anaerobic sludge blanket (UASB) reactors are used to treat soft drink wastewater, offering high-volume loading capacity, optimal grain deposition, and the ability to bear impact loads. The use of support materials can enhance biological productivity and expedite the UASB start-up period. In this study, bone powder was utilized as a support material in a UASB reactor to remove contaminants from wastewater. During the 70-day sludge adaptation period, the treatment reactor achieved a 93% reduction in COD, while the control reactor achieved a 65% reduction. Biogas production was higher in the bone powder UASB reactor (1750 mL/d) compared to the control UASB reactor (1100 mL/d), and the bone powder UASB reactor demonstrated greater resistance to shock loading. The improvement in sludge settling, shear strength, and higher biological activity in the bone powder UASB reactor was attributed to the formation of large granular sludge. The size of the granular sludge increased further with the colonization of filamentous bacteria at the irregular levels of bone powder. [ABSTRACT FROM AUTHOR]

Summary: Kinetic‐modeling studies are a key step to attain economically practical technology in terms of efficient scheme and bioreactor scale‐up to describe the substrate utilization, biomass growth, and product formation in the biohydrogen production process. Kinetic‐modeling study of biohydrogen production from molasses using mixed culture was investigated in an anaerobic activated sludge‐rotating biological contactor. Single‐substrate with endogenous metabolism and Luedeking–Piret model was used to describe the kinetic parameters at different dilution rate (0.032‐0.167 h−1) with influent concentration of 6, 15, and 24 g COD/L. The maximum experimentally estimated value of μmax, kS, and Yx/s was found to be 0.053 h−1, 9.98 g/L, and 0.11 g/g in dilution 0.167 h−1, respectively. It can be concluded that increase in dilution rate is a suitable for microbial activities in the biological hydrogen production process. Accordingly, maximum specific growth rate and hydrogen production rate will be increased. Contrariwise, decrease in dilution rate is associated with lower biomass concentration and higher endogenous metabolism. Therefore, dilution rate is an important parameter in production of biohydrogen in this bioreactor and should be kept in an appropriate range. [ABSTRACT FROM AUTHOR]

Biological reactors are the most energy-consuming facilities of conventional wastewater treatment plant (WWTP). Therefore, adjustment of aerators installation angles inside the aeration tank seems to be an effective way to ensure efficient biological performance. In this work, the biological treatment performance of Kermanshah's municipal WWTP (Kermanshah, Iran) was surveyed via varying angles of the aerators installation relative to the perpendicular. Two different aeration configurations in terms of installation angles of aerators, 30° and 45°, were considered. Effect of the aerators installation angles on variations of some operating and process parameters such as dissolved oxygen (DO), oxidation reduction potential (ORP), nitrogenous compounds, and phosphorus were pursued. From results, more DO and ORP amounts were found at the 30° angle compared to the 45° angle. However, changes trends in the DO and ORP amounts were similar at both angles. As the main conclusion, no prominent effect on remediation of carbon, nitrogenous compounds, and phosphorus was reported in these two angles. These results were justified by low influent organic loading, and also not to have appropriate conditions for nitrogen and phosphorus removal. In addition, in this study kinetic evaluation was conducted, and obtained findings were in a good agreement with literature. [ABSTRACT FROM AUTHOR]

Palm oil mill effluent (POME) is a colloidal suspension with 2–4% suspended solids. About 50% of the suspended solids are cellulosic compounds, which are not degraded in the typical biological treatment systems. Chemical (polymer-induced coagulation) and physical (settling) pretreatment methods were examined to remove the suspended solids in this study. A novel physicochemical treatment with high water recovery and sludge compressibility including three cationic polyacrylamides (C-PAM; as coagulant) and three anionic polyacrylamides (A-PAM; as flocculant) with different molecular weights and charge densities was used. The coagulants used were biodegradable. The combination of a C-PAM (Chemfloc1515C) with medium molecular weight and charge density and an A-PAM (Chemfloc 430A) with high molecular weight and charge density at doses of 300 and 50 mg/dm3showed the best total suspended solids (TSS) and chemical oxygen demand (COD) removal (96.4 and 70.9%, respectively). The optimal condition was found at pH 5, rapid mixing at 150 rpm for 1 min, and slow mixing at 40 rpm for 30 s. As a conclusion, the physiochemical pretreatment using biodegradable coagulants was a promising alternative to effectively separate TSS (96.4%) with high water recovery (76%). [ABSTRACT FROM PUBLISHER]

Hydrogen (H2) is one of renewable energy sources known for its non-polluting and environmentally friendly nature, as its end combustion product is water (H2O). The biological production of H2 is a less energy intensive alternative where processes can be operated at ambient temperature and pressure. Dark fermentation by bacterial biomass is one of multitude of approaches to produce hydrogen which is known as the cleanest renewable energy and is thus receiving increasing attention worldwide. The present study briefly reviews the biohydrogen production process with special attention on the effects of several environmental and operational factors towards the process. Factors such as organic loading rate, hydraulic retention time, temperature, and pH studied in published reports were compared and their influences are discussed in this work. This review highlights the variations in examined operating ranges for the factors as well as their reported optimum values. Divergent values observed for the environmental/operational factors merit further exploration in this field. [ABSTRACT FROM AUTHOR]

Five pretreatment methods, namely chemical, acid, heat-shock, freezing and thawing, and base, were evaluated for the enrichment of hydrogen-producing bacteria in anaerobic granulated sludge, which will be subsequently used as seed in biological hydrogen production. All the pretreatments showed positive effects towards improving hydrogen (H) generation by the microbial population with higher hydrogen production yield and COD removal efficiency as compared to control. The granulated sludge pretreated by heat-shock showed maximum accumulated H (19.48mLg-COD), COD removal efficiency (62%), and biomass concentration (22.5 gL). [ABSTRACT FROM AUTHOR]

The hydraulic characteristic of an anaerobic rotating biological contactor (AnRBC) were studied by changing two important hydraulic factors effective in the treatment performance: the hydraulic retention time ( τ) and rotational disk velocity ( ω). The reactor hydraulic performance was analyzed by studying hydraulic residence time distributions (RTD) obtained from tracer (Rhodamine B) experiments. The experiments were conducted based on a central composite face-centered design (CCFD) and analyzed using response surface methodology (RSM). The region of exploration for the process was taken as the area enclosed by τ (60, 90 and 120 min) and ω (0.8 and 16 rpm) boundaries. Four dependent parameters, deviation from ideal retention time (Δ τ), dead volume percentage and dispersion indexes (Morrill dispersion index (MDI) and dispersion number (d)), were computed as response. The maximum modeled Δ τ and dead volume percentage was 43.03 min and 37.51% at τ and ω 120 min and 0 rpm, respectively. While, the minimum predicted responses (2.57 min and 8.08%) were obtained at τ and ω 60min and 16 rpm, respectively. The interaction showed that disk rotational velocity and hydraulic retention time played an important role in MDI in the reactor. The AnRBC hydraulic regime was classified as moderate and high dispersion (d=0.09 to 0.253). As a result, in addition to the factors studied, the reactor geometry showed significant effect on the hydraulic regime. [ABSTRACT FROM AUTHOR]

Purpose: To report the indications and techniques of corneal transplantation at a tertiary referral center in Tehran over a 3-year period. Methods: Records of patients who had undergone any kind of corneal transplantation at Labbafinejad Medical Center, Tehran, Iran from March 2004 to March 2007 were reviewed to determine the indications and types of corneal transplantation. Results: During this period, 776 eyes of 756 patients (including 504 male subjects) with mean age of 41.3±21.3 years underwent corneal transplantation. The most common indication was keratoconus (n=317, 40.8%) followed by bullous keratopathy (n=90, 11.6%), non-herpetic corneal scars (n=62, 8.0%), infectious corneal ulcers (n=61, 7.9%), previously failed grafts (n=61, 7.9%), endothelial and stromal corneal dystrophies (n=28, 3.6%), and trachoma keratopathy (n=26, 3.3%). Other indications including Terrien's marginal degeneration, post-LASIK keratectasia, trauma, chemical burns, and peripheral ulcerative keratitis constituted the rest of cases. Techniques of corneal transplantation included penetrating keratoplasty (n=607, 78.2%), deep anterior lamellar keratoplasty (n=108, 13.9%), conventional lamellar keratoplasty (n=44, 5.7%), automated lamellar therapeutic keratoplasty (n=8, 1.0%), and Descemet stripping endothelial keratoplasty (n=6, 0.8%) in descending order. The remaining cases were endothelial keratoplasty and sclerokeratoplasty. Conclusion: In this study, keratoconus was the most common indication for penetrating keratoplasty which was the most prevalent technique of corneal transplantation. However, deep anterior lamellar keratoplasty is emerging as a growing alternative for corneal pathologies not involving the endothelium. [ABSTRACT FROM AUTHOR]

This study aims to investigate the efficiency of lead (Pb) adsorption by adsorbent maleate/polyacrylonitrile nanocomposite using immersing the pristine electrospun (PAN) nanofibers. Characterizations such as field emission scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy were applied to investigate the structure of the synthesized maleate nanoparticles. FESEM image indicates the smooth surface of the PAN nanofibers and the maleate nanoparticles coating on the electrospun PAN nanofibers surface. A four-factor central composite design was employed, with six replicas at the central points to optimize the process variables. The maximum Pb removal percentage of 98.5% was achieved at the initial concentration of 25 mg/L, an adsorbent dosage of 1.85 g/L, a pH of 6, and a contact time of 60 min. The adsorption process follows the Langmuir isotherm (R² = 0.99) and pseudo-second-order kinetics (R² = 0.99). The highest capacity of Pb ions adsorption through maleate/PAN nanocomposite was 349.15 mg/g that makes it a potential adsorbent in wastewater treatment. [ABSTRACT FROM AUTHOR]