Search

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]

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]

Infectious waste disinfection is an essential process in medical waste management that may cause release of some pollutants. In this study, the PAHs concentration at the disinfection was investigated. The change in the release rate of PAHs in two including infectious waste reduction and increasing the segregation ratio was estimated. The results showed that the PAHs concentration was 1172 – 2066 ng/m3. The specific concentration of PAHs was 852 ng/ton of infectious waste in average. The annual emission of the PAHs resulting from infectious waste disinfection is estimated to be 612.6 kg. Reduction of infectious waste caused by redefining infectious waste and increasing the segregation ratio leads to reduction of PAHs concentration by 50%. Increasing the ratio of segregation and redefinition of infectious waste that led to reduced waste loading volume are essential measures that reduce the emissions of pollutants as by-products of disinfection. [ABSTRACT FROM AUTHOR]