Biofilm formation and lipopeptide antibiotic iturin A production in different peptone media

Biofilm fermentation is a newly developed promising technique in fermentation technology. In this study no.3 and no.3S media have been used for the lipopeptide antibiotic iturin A production by Bacillus subtilis RB14. The main component of no.3 and no.3S media is Polypepton and Polypepton S, respectively. B. subtilis RB14 produces thick stable biofilm and high amount of iturin A in no.3S medium. Whereas, impaired biofilm formation and lower iturin A production was observed in no.3 medium. From the analytical information it was observed that the amounts of metal ions, such as K⁺, Ca²⁺ and Mn²⁺, cysteine and cellulose are lower in Polypepton compared to the Polypepton S. To investigate their effect on biofilm formation and iturin A production cysteine, cellulose, K⁺, Ca²⁺ and Mn²⁺ were added respectively into the no.3 medium at similar amount that Polypepton S contains. It was observed that individual addition of K⁺, Ca²⁺, cysteine and cellulose had no effect on biofilm formation, cellular growth induction or iturin A production. However, when Mn²⁺ was supplemented in no.3 medium, biofilm development was restored with an improved production of iturin A. Finally, combined addition of investigated substances into the no.3 medium resulted with highly folded, thick biofilm with high cellular growth and iturin A production compared to the original no.3 medium.     

Conversion of Mixed Low-Density Polyethylene Wastes into Liquid Fuel by Novel CaO/SiO<Subscript>2</Subscript> Catalyst

Plastic wastes disposal can be done by various methods such as landfill, incineration, mechanical and chemical recycling but these are restricted due to some environmental, economic and political problems. Conversion of these plastic wastes into valuable products by degradation is the best option. In the present work waste low density polyethylene was degraded by catalytic process using CaO/SiO₂ as mixed catalyst. The conditions for catalytic degradation were optimized for the production of maximum liquid fuel. It was found that the yield of liquid product was up to 69.10 wt% at optimum condition of temperature (350 °C), time (90 min) and catalyst feed ratio (1:0.4). Liquid fuels obtained from the catalytic degradation were further separated into various fractions by fractional distillation. Composition of liquid fuels was analyzed by FTIR spectroscopy, which showed that the liquid fuels mostly consist of paraffinic and naphthenic hydrocarbons. Different fuel properties such as density, specific gravity, American petroleum institute gravity (API gravity), viscosity, kinematic viscosity, refractive index, refractive intercept and flash point of both the parents and various fractional fuels were determined. All the properties of the obtained fuels are in close agreement with the fuel properties of gasoline, kerosene and diesel. It was found that our catalyst is very much efficient in terms of time, degradation temperature and amount of catalyst.     

Genotoxicity of ferric oxide nanoparticles in Raphanus sativus: Deciphering the role of signaling factors, oxidative stress and cell death

We have studied the genotoxic and apoptotic potential of ferric oxide nanoparticles(Fe_2O_3-NPs) in Raphanus sativus(radish).Fe_2O_3-NPs retarded the root length and seed germination in radish.Ultrathin sections of treated roots showed subcellular localization of Fe_2O_3-NPs,along with the appearance of damaged mitochondria and excessive vacuolization.Flow cytometric analysis of Fe_2O_3-NPs(1.0 mg/m L) treated groups exhibited 219.5%,161%,120.4% and 161.4% increase in intracellular reactive oxygen species(ROS),mitochondrial membrane potential(ΔΨm),nitric oxide(NO) and Ca2+influx in radish protoplasts.A concentration dependent increase in the antioxidative enzymes glutathione(GSH),catalase(CAT),superoxide dismutase(SOD) and lipid peroxidation(LPO) has been recorded.Comet assay showed a concentration dependent increase in deoxyribonucleic acid(DNA) strand breaks in Fe_2O_3-NPs treated groups.Cell cycle analysis revealed 88.4% of cells in sub-G1 apoptotic phase,suggesting cell death in Fe_2O_3-NPs(2.0 mg/m L) treated group.Taking together,the genotoxicity induced by Fe_2O_3-NPs highlights the importance of environmental risk associated with improper disposal of nanoparticles(NPs) and radish can serve as a good indicator for measuring the phytotoxicity of NPs grown in NP-polluted environment.     

Determining the robust optimal set of BMPs for urban runoff management in data-poor catchments

Mismanagement of urban runoff can result in inundation which causes serious problems in providing urban services. Best management practices (BMPs) are used for urban runoff management. In this study, a method is proposed to determine the robust optimal set of BMPs for runoff management in data-poor catchments in urban areas. This method includes five main steps: (1) Sensitivity analysis to determine effective parameters in rainfall-runoff simulation model, (2) Calibration of the rainfall-runoff model based on selected effective parameters, (3) Developing a multi-objective optimization model to obtain the optimal sets of BMPs, (4) Selecting the final solutions using the Nash approach for ranking, (5) Evaluation of the robustness of the selected solution using the Management Option Rank Equivalence method. The proposed method is examined in an urban basin located in the north of Tehran, Iran. The results show that the proposed approach provides reliable results for urban runoff management in data-poor areas.     

Solar Disinfection of Water for Inactivation of Enteric Viruses and its Enhancement by Riboflavin

Solar disinfection (SODIS) has been described as a cheap and effective method of treating contaminated water to inactivate pathogenic microorganisms. In this study, SODIS was assessed for its efficacy in inactivating three enteric viruses (coxsackievirus B3, coxsackievirus B5 and poliovirus), either on its own or in the presence of riboflavin as a disinfection enhancer. On its own, SODIS produced a reduction of virus infectivity of 4–6 log₁₀ in 6 h. In the presence of riboflavin, inactivation was more rapid in all viruses studied, and with coxsackievirus B5 and poliovirus an extra 1–2 log₁₀ increase in reduction of infectivity was observed after 6 h exposure. This study provides a practical example of low technology methods which could be utilised to provide safe drinking water in various circumstances.     

A hybrid model for robust design of sustainable closed-loop supply chain in lead-acid battery industry

Environmental Science and Pollution Research - Considering supply chain efficiency during the network design process significantly affect chain performance improvement. In this paper, the design...     

The formation of aerobic granular sludge for the treatment of real landfill leachate using a granular sequencing batch reactor at a constant volume

Leachate generated in a landfill may not be treated by conventional biological treatment due to its nature and complexity. The process of forming aerobic granules in batch sequencing reactors having features such as; reducing the settling process time and saving energy consumption and high decomposition rate have been noticed by researchers. In the present study, the structure of sequencing batch reactors (SBRs) was evaluated for the formation of granules, which were subsequently utilized for the treatment of landfill leachate. The experiment was initiated by using the GSBR, containing 1200 ml with different apparatuses, to develop granular sludge, and synthetic wastewater was added to reinforcement. The selected parameters for the operational hydraulic retention time (HRT) of the wastewater (6-h cycles) included feeding, idle, aeration, settling, and discharge. Furthermore, the controlled conditions were the dissolved oxygen (DO) range of 2–2.2 mg/L, temperature range of 20–23℃, and pH of 7.5–8.3. The chemical oxygen demand (COD), mixed liquor suspended solids (MLSS), and sludge volume index (SVI) daily were measured at the influent and effluent of GSBR reactor. The main properties of aerobic granular sludge were identified during the research procedures, and the remarkable settling and potent, high-density microbial structure of the granules were confirmed. The mean size of the formulated granules was estimated at 7.46 ± 1.8 mm, and the volume of the biomass also increased from approximately 1607 to 4137 mg/L through the granulation process. Moreover, 98% of the influent chemical oxygen demand (COD) could be removed by the formulated granular sludge, and the final-stage organic loading rate was estimated at 5.65 COD/m³/day. According to the results, GSBRs could be employed for the formulation of aerobic granular sludge for the treatment of landfill leachate.     

Multi-objective conflict resolution optimization model for reservoir’s selective depth water withdrawal considering water quality

Environmental Science and Pollution Research - This paper develops a multi-objective conflict resolution simulation-optimization model based on a leader-follower game to resolve conflicts between...     

Photocatalytic degradation of the acetaminophen by nanocrystal-engineered TiO2 thin film in batch and continuous system

• Photocatalytic activity was improved in TiO₂ thin film by rapid thermal annealing. • Photoreactor was designed for TiO₂ thin film. • Considerable reusability and durability of prepared photocatalysts were studied. Un-biodegradable pharmaceuticals are one of the major growing threats in the wastewaters. In the current study, TiO₂ thin film photocatalysts were designed by nanocrystal engineering and fabricated for degradation of the acetaminophen (ACE) in a photocatalytic reaction under UV light irradiation in batch and continuous systems. The photocatalyst was prepared by sputtering and then engineered by thermal treatment (annealing at 300℃ (T300) and 650℃ (T650)). The annealing effects on the crystallinity and photocatalytic activity of the TiO₂ film were completely studied; it was found that annealing at higher temperatures increases the surface roughness and grain size which are favorable for photocatalytic activity due to the reduction in the recombination rate of photo-generated electron-hole pairs. For the continuous system, a flat plate reactor (FPR) was designed and manufactured. The photocatalytic performance was decreased with the increase of flow rate because the higher flow rate caused to form the thicker film of the liquid in the reactor and reduced the UV light received by photocatalyst. The reusability and durability of the samples after 6 h of photocatalytic reaction showed promising performance for the T650 sample (annealed samples in higher temperatures).