Statistical Design and Analysis of Experiments

The present research deals with degradation of amoxicillin (AMX) in an immobilized TiO 2 photocatalytic reactor under UVA irradiation (365 nm). Enhancement of photocatalysis by sequence aeration and addition of ozone and H 2 O 2 was also evaluated. Relationship between three numerical independent variables (chemical oxygen demand (COD in ), reaction time and initial pH) and four process responses (COD removal efficiency, specific COD removal rate (SRR), BOD 5 /COD ratio, and final pH) for the synthetic amoxicillin wastewater (SAW) photocatalyst oxidation process were analyzed and modeled using response surface methodology (RSM). The region of exploration for the process was taken as the area enclosed by COD in concentration (400–2000 mg/L), initial pH (3–11) and reaction time (20–240 min) boundaries. As a result, initial COD showed different impact at different pH on the COD removal efficiency. The maximum BOD 5 /COD ratio found 0.43 at initial COD 2000 mg/L and pH of 3. The maximum COD removal efficiency for the photocatalytic reaction alone was 20%, while the value could be improved up to 38% by sequence aeration. The photocatalytic process induced by O 3 and O 3 /H 2 O 2 showed COD removal efficiencies of 53 and 58%, respectively. As a conclusion, the photocatalyst process induced by O 3 and O 3 /H 2 O 2 could be an appropriate pretreatment method prior to a biological treatment process.

Statistical modeling of photocatalytic degradation of synthetic amoxicillin wastewater (SAW) in an immobilized TiO2 photocatalytic reactor using response surface methodology (RSM)

This research was conducted to study the adsorption of ammonium ions onto pumice as a natural and low-cost adsorbent. The physico-chemical properties of the pumice granular were characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Modeling and optimization of a NH4 + sorption process was accomplished by varying four independent parameters (pumice dosage, initial ammonium ion concentration, mixing rate and contact time) using a central composite design (CCD) under response surface methodology (RSM). The optimum conditions for maximum removal of NH4 + (70.3) were found to be 100 g, 20 mg/l, 300 rpm and 180 min, for pumice dosage, initial NH4 + ion concentration, mixing rate and contact time. It was found that the NH4 + adsorption on the pumice granular was dependent on adsorbent dosage and initial ammonium ion concentration. NH4 + was increased due to decrease the initial concentration of NH4 and increase the contact time, mixing rate and amount of adsorbent. Â© 2016 Archives of Environmental Protection.

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Response surface methodology (RSM) and its application for optimization of ammonium ions removal from aqueous solutions by pumice as a natural and low cost adsorbent

A novel stacked flow-through electro-Fenton reactor as decentralized system for the simultaneous removal of pollutants (COD, NH3-N and TP) and disinfection from domestic sewage containing chloride ions

http://eprints.um.edu.my/9419/1/Effects_of_biomass%2C_COD_and_bicarbonate_concentrations_on_fermentative_hydrogen_production_from_POME_by_granulated_sludge_in_a_batch_culture.pdf

Effects of biomass, COD and bicarbonate concentrations on fermentative hydrogen production from POME by granulated sludge in a batch culture

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 (Δτ), dead volume percentage and dispersion indexes (Morrill dispersion index (MDI) and dispersion number (d)), were computed as response. The maximum modeled Δτ 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.

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Hydraulic characteristics analysis of an anaerobic rotatory biological contactor (AnRBC) using tracer experiments and response surface methodology (RSM)

Solid-phase extraction (SPE) combined with deep eutectic solvent based dispersive liquid–liquid microextraction (DES-DLLME) has been developed as a highly sensitive technique for the ultra preconcentration of estrogenic compounds in wastewater samples prior to their analysis by gas chromatography-mass spectrometry (GC-MS). This coupling not only allows for the extraction of compounds from complex matrices such as sewage and wastewater, but also provides very high enrichment factors. In this technique, a new deep eutectic solvent (DES) was prepared by blending citric acid monohydrate and 1-octyl-3-methylimidazolium chloride at a molar ratio of 1 : 1. Variables affecting the performance of both steps were thoroughly investigated. Under the optimized conditions, the enrichment factors and extraction efficiency are between 33 000–41 000 and 55–68%, respectively. The SPE–DES-DLLME provided a high enrichment factor for estrogenic compounds. The limits of detection (LODs) are in the range of 0.01–0.05 ng L−1 and the calibration graphs are linear in the range of 0.03–50 ng L−1. The values of relative standard deviation (RSD) for intra-day and inter-day based on seven replicate measurements of 0.50 ng L−1 of estrogenic compounds and 0.30 ng L−1 for the internal standard in wastewater were in the range of 1.5–2.5% and 2.6–3.8%, respectively. The relative recoveries of wastewaters which have been spiked with different concentrations of target compounds are 90–108%.

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Solid-phase extraction followed by deep eutectic solvent based dispersive liquid–liquid microextraction and GC-MS detection of the estrogenic compounds in wastewater samples

Reza Davoodi

Papers

Hydraulic characteristics analysis of an anaerobic rotatory biological contactor (AnRBC) using tracer experiments and response surface methodology (RSM)

Solid-phase extraction followed by deep eutectic solvent based dispersive liquid–liquid microextraction and GC-MS detection of the estrogenic compounds in wastewater samples