The Effect of Organic Loading on Propylene Glycol Removal Using Fixed Bed Activated Sludge Hybrid Reactor

Propylene glycol is discharged to the surface and underground waters and vicinity soils via industrial wastewater effluents, posing many health and environmental risks. The main goal of this study was to remove propylene glycol from synthetic wastewater in a fixed bed activated sludge reactor. To observe the effects of organic loading on bioreactor performance, the organic loading was increased by two sequencing stages: first by hydraulic retention time (HRT) depletion and second via propylene glycol concentration increase. Propylene glycol removal efficiency in HRTs of 8, 6, 4 and 2 h was 95.86, 95.12, 93.96 and 79.08 % respectively. A constant HRT of 6 h was selected for the second stage; propylene glycol concentrations of 500, 1000, 1500, 2000 and 2500 mg L–1 were used. The removal efficiency for these concentrations was 95.12, 95.95, 88.54, 75.95 and 35.69 % respectively. Thus, the integrated fixed bed activated sludge reactor is an efficient, viable and promising technology for treating wastewaters containing propylene glycol

Removal of styrene from waste gas stream using a biofilter

280 tyrene is produced in large quantities in the chemical industries and its monomer constitutes the building block for the production of polystyrene, styrene copolymers, polyester resins, and rubber. It is also used in the production of fiberglass boats, storage tanks, pipes, shower units and car parts. Besides the known industrial releases from the production and processing units, styrene is also generated in smaller quantities from other sources such as natural microbial and fungal metabolism, cigarette smoke, automobile exhaust, and the pyrolysis and cracking of petroleum and its derivatives S Original Article Removal of styrene from waste gas stream using a biofilter B. Bina*, R.Dehghanzadeh *, H. Pourmoghadas *, A.Kalantary *, A.Torkian** ABSTRACT Background: Styrene is produced in large quantities in the chemical industries and it has been listed among the 189 hazardous and toxic atmospheric contaminants under Clean Air Act Amendments, 1990, due to its adverse effects on human health. The biofiltration has been widely and efficiently applied during recent decades for the treatment of air streams contaminated by volatile organic compounds at low concentrations. Also this technology has been applied widely and efficiently in the removal of styrene from waste gas streams

Optimization of dimethyl phthalate degradation parameters using zero-valent iron nanoparticles by response surface methodology: Determination of degradation intermediate products and process pathway

Background and purpose: Phthalic acid esters (PAEs) are a group of organic compounds that are used as additives in plastic industry. Among PAEs, dimethyl phthalate (DMP), the simplest compound in phthalates, is an aromatic pollutant that disturbs endocrine function. The aim of this study was to assess the effect of zero-valent iron nanoparticles (NZVI) on the DMP degradation. Materials and methods: NZVI were prepared by reduction of ferric chloride using sodium borohydride. Physical properties of nanoparticles were determined using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), and Vibrating Sample Magnetometer (VSM). Then, the effect of pH, DMP concentrations, the amount of NZVI, and contact time were investigated on DMP removal efficiency. Response surface methodology based on Box- Behnken was used to study the interaction between variables. Results: Maximum efficiency (99) of DMP removal by NZVI was achieved in optimum conditions (pH=3, NZVI dosage =0.6 g/l, DMP concentration = 2 mg/l, and contact time= 65 min). The Box-Behnken analysis confirmed that pH and NZVI dosage have had the highest and lowest effect in the process of DMP removal by NZVI, respectively. Conclusion: According to findings, NZVI in small amounts have a proper efficiency in DMP removal. Also, DMP degradation efficiency did not change much, after being used in five consecutive cycles of degradation reactions. This shows a potential application prospect of the synthesized NZVI in real water treatment. © 2015 Journal of Mazandaran University of Medical Sciences. All Rights Reserved

Optimization of dimethyl phthalate degradation parameters using zero-valent iron nanoparticles by response surface methodology: Determination of degradation intermediate products and process pathway

Background and purpose: Phthalic acid esters (PAEs) are a group of organic compounds that are used as additives in plastic industry. Among PAEs, dimethyl phthalate (DMP), the simplest compound in phthalates, is an aromatic pollutant that disturbs endocrine function. The aim of this study was to assess the effect of zero-valent iron nanoparticles (NZVI) on the DMP degradation. Materials and methods: NZVI were prepared by reduction of ferric chloride using sodium borohydride. Physical properties of nanoparticles were determined using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), and Vibrating Sample Magnetometer (VSM). Then, the effect of pH, DMP concentrations, the amount of NZVI, and contact time were investigated on DMP removal efficiency. Response surface methodology based on Box- Behnken was used to study the interaction between variables. Results: Maximum efficiency (99) of DMP removal by NZVI was achieved in optimum conditions (pH=3, NZVI dosage =0.6 g/l, DMP concentration = 2 mg/l, and contact time= 65 min). The Box-Behnken analysis confirmed that pH and NZVI dosage have had the highest and lowest effect in the process of DMP removal by NZVI, respectively. Conclusion: According to findings, NZVI in small amounts have a proper efficiency in DMP removal. Also, DMP degradation efficiency did not change much, after being used in five consecutive cycles of degradation reactions. This shows a potential application prospect of the synthesized NZVI in real water treatment. © 2015 Journal of Mazandaran University of Medical Sciences. All Rights Reserved

EFFECT OF HUMIC COMPOUNDS ON BACTERIAL GROWTH IN BIOREMEDIATION OF PAHS

Polycyclic Aromatic Hydrocarbons (PAHs) which are introduced into environment are potentially carcinogenic, mutagenic and toxic contaminants. The effect of extractable humic substances (EHS) on bacterial density in bioremediation of anthracene in liquid systems was investigated. The ratio of EHS to anthracene were in two concentrations of 0.35 and 1.05 g dry EHS (with 30% organic matter) per one mg anthracene. In the tests with EHS, an increase in bacterial density even by 8 fold of magnitude was seen in 12-15 days. Then a fast decrease was occurred and prolonged till the end of the test time for the tests that had EHS without anthracene. In the tests which anthracene was the only substrate increasing in bacterial population was not seen. The results showed that up to 21 days the system was free from degradation. So the first increasing in bacterial population showed that EHS might be used as a readily substrate for PAH degraders. The presence of EHS (fulvic and humic acid) can stimulate bacterial community and activity that caused enhancement in anthracene bioremediation

Micromechanical formulation of the mobilized stress ratio under principal stress rotation in granular materials

In this paper the mobilized stress ratio is investigated by using the static equilibrium at the micro scale level analysis. The mobilized stress ratio is obtained in the distribution of the contact normal, E(β), and the inter-particle mobilized friction angle, ϕμ . The second invariant of the fabric tensor, α is used to account for fabric and its evolution. There is a difference between the theoretical rotation of principal stress axes that is obtained by the classical equations of the mechanics of materials and the experimental rotation of principal stress axes. The experimental rotation is related to the anisotropic parameter, α. The noncoincidence between the theoretical and experimental is related to the relative direction of the mobilized plane and the bedding plane. A comparison with experimental tests demonstrates the validity of this formulation