A comparative study on performance of the conventional and fixed-bed membrane bioreactors for treatment of Naproxen from pharmaceutical wastewater.

Here, a comparative study was designed to survey the treatment efficiency of pharmaceutical wastewater containing Naproxen by Membrane bioreactor (MBR) and MBR with fixed-bed packing media (FBMBR). To this end, the performance of MBR and FBMBR in different aeration conditions including average DO (1.9-3.8 mg/L), different organic loading (OLR) (0.86, 1.14 and 1.92 kg COD per cubic meter per day), and Naproxen removal efficiency. The BOD5 removal efficiency, effluent quality and membrane fouling were monitored within 140 days. The results obtained from the present study indicated that COD removal efficiency for FBMBR (96.46%) was higher than that for MBR (95.33%). In addition, a high COD removal efficiency was experienced in both MBR and FBMBR in operational conditions 3 and 4, even where OLR increased from 1.14 to 1.92 kgCOD/m3 d and DO decreased from 4 to < 1 mg/L. Furthermore, the higher Naproxen removal efficiency was observed in FBMBR (94.17%) compared to that for MBR (92.76%). Therefore, FBMBR is a feasible and promising method for efficient treatment of pharmaceuptical wastewater with high concentrations of emerging contaminant, especially, the Naproxen.

Emission of BTEX compounds from the frying process: Quantification, environmental effects, and probabilistic health risk assessment.

Frying is one of the cooking methods which generates mono aromatic hydrocarbons, including benzene, toluene, ethylbenzene, and xylene (BTEX); subsequently, it affects health through carcinogenic (CR) and non-carcinogenic risks (n-CR). However, their environmental effects known by secondary organic aerosols (SOA) and ozone formation potential (OFP) were also attended by many scientists. Therefore, this study quantified the BTEX emissions from 4 types of most commonly used edible oils (canola, corn, sunflower, and blend) under various frying conditions of temperatures and food additives. Furthermore, the effects of the chemicals in the light of health (CR and n-CR) and environment (SOA and OFP) were also investigated. The study results showed that higher temperatures could significantly increase the emissions, while the addition of food ingredients significantly reduces the emissions. The rank order of emitted chemical was obtained as T > B > E > X. The blend had the most emission among oils, followed by, in descending order, corn, sunflower, and canola. In association with environmental effects, the orders of X > T > E > B and T âˆ¼ E > X > B were obtained for OFP and SOA, respectively. THQ for blend, corn, canola, and sunflower oils was higher than 1 (1.76, 1.35, 1.27, and 1.002, respectively), showing a considerable n-CR when the hood was off. In this respect, TCR for the oils (1.78 × 10-4, 1.45 × 10-4, 1.39 × 10-4, and 1.05 × 10-4, respectively) shown the probable risk for all oils. Moreover, hood switching reduced the risk by about 11-81%.

Improvement of montmorillonite adsorption capacity for lead ions by modifying with hexadecyl trimethyl ammonium chloride: Characterization, modelling and optimization studies.

Heavy metal pollutants, particularly Pb are considered as critical contaminants causing harmful health risks for a human. In this study, montmorillonite modified with hexadecyl trimethyl ammonium chloride surfactant (N-HTAC) was applied as a new adsorbent for the Pb+2 adsorption from aqueous solutions. The N-HTAC was characterized by the scanning electron microscopy, x-ray diffraction, energy-dispersive x-ray spectroscopy, and Brunauer-Emmett-Teller. The central composite design using R software was chosen for modelling the effect of operating parameters. Based on the findings obtained from the analysis of variance, reduced full second-order model with multiple R2, 0.94, adjusted R2, 0.93, and LoF, 0.96, was represented satisfactory adjustment with experimental data. The Solver "add-ins" was employed to gain the optimum conditions for the modelling. The optimum operating points giving the maximum Pb+2 removal (99.99%), were found to be initial Pb+2 concentration: 0.1 mg L1- adsorbent dosage: 4.33 g L-1, HTAC dosage: 4.19 g L-1, pH: 7.13, temperature: 28.06ºC, and the reaction time: 103.4 min. The findings of the study showed that by enhancing and improving natural adsorbents, a significant amount of environmental pollutants can be eliminated. •In this study, a new modified adsorbent (N-HTAC) was used to remove lead ions.•The results of this study showed that the N-HTAC used has high efficiency (99.99%) in the removal of lead.•The results of this study and the data obtained can be used to supplement the information on the removal of contaminants with adsorbents.

Magnetic chitosan nanocomposite: Fabrication, properties, and optimization for adsorptive removal of crystal violet from aqueous solutions.

Recovery of crystal violet (CV) dye was investigated using magnetic chitosan nano-composites (MCNCs) and the effects of process variables (contact time, initial CV concentration, adsorbent dose, and pH) were optimized through response surface methodology. The reliability of the RSM models (first-order model, first model with interaction, the second-order model, and reduced model) was tested by fitting the data. A comparative analysis of the results derived from the models demonstrated that the reduced model was the best. According to modelling results, MCNCs dosage and contact time were found to be the most effective variables on the adsorption efficiency procedure, respectively. Also, pH had no significant effect on the adsorption uptake statistically. MCNC has the maximum adsorption efficiency (72%) when the contact time, adsorbent dosage, and initial concentration of CV were optimally set as 140 min, 1 g, and 77 mg/L, respectively. Quantity uptake of CV was evaluated using the Langmuir, Freundlich, and Temkin models. Based on findings, Freundlich isotherm fitted well with the experimental results. Kinetic studies showed that the pseudo-first-order model fitted the best the experimental data, which indicated that the adsorption rate of CV molecules onto MCNC was time-dependent. The studies on the well regenerability of MCNC in addition to its high potentiality of cationic dyes removal make it an attractive adsorbent in terms of dye-containing wastewaters treatment.

Removal of pollutants (COD, TSS, and NO3-) from textile effluent using Gambusia fish and Phragmites australis in constructed wetlands.

In developing countries, the discharge of polluted effluents into the environment has caused environmental problems. For this purpose, constructed wetlands are attracting great concern owing to their low cost and less operation and maintenance requirements. The main aim of this work was to study the effectiveness of constructed wetlands utilizing Phragmites australis plants and Gambusia fish in the treatment of textile effluent. The constructed wetlands are located in the eastern part of a wastewater treatment plant near a grit chamber unit. This research was carried out in four polyethene rectangular tanks with a capacity of 80 L. The tanks were filled to about 20% with sand with a porosity of 48% and the diameter of the gravel bed used in the horizontal sub-surface flow unit varied between 5 and 25 mm. The results of different tanks showed the highest and lowest removal efficiencies of chemical oxygen demand (COD) were in the tanks containing Phragmites australis/Gambusia fish and Phragmites australis, respectively. The best tank for the removal of total suspended solids (TSS) was the tank containing the Phragmites australis and the Gambusia fish. In the tank containing the Phragmites australis plants, the removal efficiency of NO3-, COD, and TSS was in the range of 40-70, 68-72, and 49-71%, respectively. The maximum increase of nitrate, approximately 78%, was observed in tank 2, which contained only fish. In the control tank, the removal efficiency of NO3-, COD, and TSS was in the range of 0-10, 10-18, and 15-25%, respectively. The results of this study showed that if these systems were properly designed and operated, they could be used to treat various wastewaters, especially in developing countries.

Use of municipal, agricultural, industrial, construction and demolition waste in thermal and sound building insulation materials: a review article.

Production and usage of green and sustainable building materials realizes the desire to integrate more biodegradable, natural, recycled, and renewable resources into the construction industry. The aim is to replace traditionally available construction industry materials due to their environmental impacts through air emissions and waste generation. An observed trend is the production of insulation materials by recycling of industrial, agriculture, construction and demolition (C&D), and municipal solid wastes, thus reducing the environmental burdens of these wastes. While thermal insulation is important in saving energy, sound insulation has drawn much attention in recent years. There are various waste materials that have good thermal and sound properties, enabling effective replacement of traditional materials. This review investigates the use of industrial, agricultural, C&D, and municipal solid wastes to produce innovative thermal and acoustic insulating building materials. The performance of these insulating materials, and the influence of several materials parameters (density, thermal conductivity, sound absorption coefficient) on thermal and acoustic performance are reported after a brief description of each material.