Removal of COD and TOC From Petroleum Synthetic Wastewater Containing Cyclic Aromatic Hydrocarbons Using the Photo-Fenton Process by the Box-Behnken Method

Background: In the last few decades, concern over environmental safety has increased significantly. One of the main causes of environmental degradation is the discharge of untreated pollutants into water bodies. This study examined the efficiency of the photo-Fenton oxidation process to remove chemical oxygen demand (COD) and total organic carbon (TOC) from petroleum wastewater.Methods: Experiments were designed using the Box-Behnken method- a model of the response surface method (RSM) by MINITAB software. First, a wooden chamber equipped with UV lamps installed in the center was applied. The effect of effective parameters on the photo-Fenton process, including naphthalene concentration (10-70 μg/L), pH (2-7), H2O2 (50-800 mg/L), Fe (5-80 mg/L), contact time (10-120 minutes) and UV rays was investigated.Results: The highest removal efficiency of the COD (case 89.27) was at achieved at pH = 2, UV = 24, naphthalene concentration 10 μg/L, Fe concentration 36.06 mg/L, hydrogen peroxide content 800 mg/L, and contact time 120 min. Besides, the highest removal efficiency of the process in removing TOC was 71.04% obtained at 2 pH = 24, UV = 24, and a reaction time of 120 min.Conclusion: Based on the results of this research, the photo-Fenton process has a significant efficiency in removing COD and TOC from petroleum effluents containing cyclic aromatic hydrocarbons and can be utilized as an efficient method for the treatment of petroleum wastewaters

Performance of Pumice Stone as a Packing in Fixed-bed Aerobic Bioreactor

In this research, the performance of pumice stone as a fixed bed support in the biological treatment of the synthetic wastewater of sugar beet factory was evaluated. Pumice is a volcanic rock having high porosity and specific surface. and in comparison with other supports, pumice has a very low price. The experiments were done on an up-flow biofilm reactor, the effective volume of which was 14.2 L, with pumice fixed bed supports. After the starting period, the reactor was operated in steady-state mode, which lasted 222 days, at hydraulic retention time of 12, 16 and 24 hours and influent COD concentration of 750, 1500 and 2250 mg/L. During the operation, the contamination removal efficiencies from 89 to 97 percent were achieved in 9 experimental runs. The results demonstrate that in organic loading rate from 750 to 4500 gr.COD/m3/day in the mentioned status the reactor's efficiency is satisfactory. In addition, some kinetic prevalent models were tested with the experimental data. Results show that according to the regression coefficients, Grau second order kinetic model and modified Stover-Kincannon model are appropriate for predicting similar reactors situations and designing new reactors, and the related equations were derived

Comparison of “Morning Olifera Seed Extract and Magnafloc LT25” in Removal of Water Turbidity Case Study: Tehran’s Jalalieh (1) Water Treatment Plant)

Coagulation-flocculation is one of the most important processes for water treatment, commonly used all over the world. The use of synthetic polymers known as “Polyelectrolytes as a coagulant aid is now wide spread in water treatment plants. Tehran’s “Jalalieh WTP” has been using an anionic polyelectrolyte under the trade name of “Magna Floc LT25” for a number of years MagnaFloc LT25 (MF-LT25) is a synthetic coagulant with high molecular weight, produced in granular and powder form. The application of this coagulant aid is known to be most effective if injected to water after addition of main coagulant (Ferric Chloride in Tehran’s WTP).  However the use of synthetic polymers in treatment of drinking water has always been under question due to extract of MO seed contains proteins soluble in water which have high coagulating properties. This pilot scale study was performed to compare the coagulating properties of seed extract of MO to MF-LT25, The tests were carried out on Tehran’s raw water in Jalalieh treatment plant. Several turbidity ranges such as 5, 20, 100, and 200 NTU were used representing real seasonal turbidities of influent water to treatment plant. Optimum concentration of the coagulant and coagulant aid was determined within water pH values of 6, 7 and 8, using common “Jar Test” technique. The extract of Moringa Oleifera seed in optimum concentration of 10, 14,25,35 mg/L and optimum pH of 8 is capable in removal of 96.5, 97.4, 98.5 and 99% of water turbidity range of 5, 20, 100, and 200 NTU respectively. Under similar conditions, MF-LT25 removal efficiency were found 97, 98.1, 98.4 and 99.4% of water turbidity range of 5, 20, 100, and 200 NTU at optimum concentrations of 0.015, 0.02, 0.025, 0.03 mg/L respectively. The results also showed that the extract of Moringa Oleifera seed is a powerful coagulating agent, at alkalinity pH values, and is more effective for high turbid waters. It compared well with synthetic polyelectrolyte as a coagulating agent. Due to possibility of its production locally, and its excellent properties it could be considered as a potential substitute for more expensive imported polymers such as Magnafloc- LT25

Synthesis of zero-valent iron nanoparticles via electrical wire explosion for efficient removal of heavy metals

In this paper, electrical wire explosion (EWE) was used as a simple, clean, in situ method to synthesise nano zero-valent iron (nZVI) particles in liquid mediums. The structural and physical properties of the synthesised nZVI particles were characterised by x-ray diffraction, Brunauer–Emmett–Teller analysis, field emission scanning electron microscopy and transmission electron microscopy. The synthesised spherical nanoparticles, at a specific size of 10–50 nm, possessed large surface areas of approximately 13.27 m/g, reinforcing the significant advantages of EWE, that is, less aggregation and in situ production of nanoparticles with enhanced removal efficacy, for groundwater treatment. After 1 h the adsorption capacity for Cr(VI), Ni(II), and Cd(II) (Q = C/C (mg/g)) at pH 4 was approximately 143.4 (89.0%), 137.5 (79.0%), and 132.6 mg/g (72.0%), respectively. The effect of temperature was also examined at initial metal ions concentration of 70 mg/L, nZVI dosage of 0.2 g/L and pH 4. The results showed 45°C was the optimum temperature for adsorption of Cr(VI), Ni(II), and Cd(II) ions, and over a 60-min period at this temperature adsorption capacity increased to 153.56 (95.3%), 158.91 (91.3%), and 163.90 mg/g (89.0%), respectively

Simultaneous ammonium and nitrate removal by a modified intermittently aerated sequencing batch reactor (SBR) with multiple filling events

Optimized methods for simultaneous removal of nitrate, nitrite and ammonium are important features of nutrient removal. Nitrogen removal efficiency in an intermittently aerated sequencing batch reactor (IA-SBR) with multiple filling events was studied. No external carbon source was added and three filling events were considered. Oxidationreduction potential (ORP) and pH curve at solids retention time (SRT) of 20 d were analyzed. Effects of three organic loading rates (OLR), 0.67, 1.0 and 1.5 kgCOD/m3d, and three nitrogen loading rates (NLR), 0.054, 0.1 and 0.15 kgN/m3d, on nitrogen removal were studied. Nitrate Apex in pH curve and Nitrate Knee in ORP profile indicated that the end of denitrification would be achieved sooner. The kinetic coefficients of endogenous decay (kd) and yield (Y) were identified to evaluate heterotrophic specific denitrification rate (SDNRb). In period 2 at NLR of 0.054 kgN/m3d and considering 2 anoxic and 3 aerobic phases, nitrogen removal efficiency was 91.43%

Application of moving bed biofilm reactor in the removal of pharmaceutical compounds (diclofenac and ibuprofen)

Pharmaceutical waste has attracted significant attention in the past two decades due to the current high consumption of pharmaceuticals together with the development of reliable detection technologies. In order to acquire better understanding on pharmaceuticals removal in biological processes, the treatment of synthetic wastewater containing diclofenac (DFN) and ibuprofen (IBU), two of the most commonly prescribed medicines worldwide, was studied using a moving bed biofilm reactor (MBBR). An 8.5-L aerobic MBBR with Kaldnes packing filling ratio of 40% was designed. The controlled parameters were pH within neutral range, temperature of 37 °C, mixed liquor suspended solids (MLSS) of 2100 mg/L, and attached growth equal to 1300 mg/L. Tests were conducted for four different initial pharmaceuticals concentrations: 2, 4, 7 and 10 mg/L, two hydraulic retention times (HRT): 5 and 10 h and two chemical oxygen demands (COD): 500 and 1000 mg/L. Results demonstrated that generally, DFN had higher removal percentage than IBU in the MBBR. At HRT = 10 h, DFN removal was between 30.83 and 66.01%, while it was 11.33 and 37.33% for IBU. At HRT = 5 h, DFN and IBU removal were respectively between 31.10–65.33 and 0–35.10%. It can be concluded that HRT = 5 h is the optimal time for DFN, while 10 h HRT promises noticeably better IBU removal. Furthermore, results revealed that DFN is better removed in the lower COD, while IBU showed better removal in the higher COD. Finally, the study on their toxicity reveals that pharmaceuticals exert slightly negative effect on COD removal

Fouling reduction of emulsion polyvinylchloride ultrafiltration membranes blended by PEG: the effect of additive concentration and coagulation bath temperature

In the present work, ultrafiltration membranes were prepared using emulsion polyvinyl chloride (EPVC) with the addition of various concentrations of polyethylene glycol (PEG) to investigate the morphological structure and separation properties. The effects of polymer concentration, coagulation bath temperature (CBT), and PEG (6\ua0kDa) concentrations—a pore former hydrophilic additive—were studied. Through the phase inversion, the membranes—which were induced by immersion precipitation in a water coagulation bath—were fabricated through dissolving EPVC in N-methyl-pyrrolidinone, a polymer solvent. Morphological features of the membranes were characterized through scanning electron microscopy, pore size and porosity, and contact angle measurements. Water and bovine serum albumin (BSA) were used in order to study the separation and permeation performance of the fabricated membranes at 3\ua0bar, which is operating pressure. The results which were obtained from contact angle test indicated an increment in the membranes hydrophilicity with an increase in PEG concentrations, and then it decreased again. Increasing the CBT led to macrovoid formation in the membrane structure and the appreciation of both membrane permeability and BSA rejection. The addition of PEG resulted in a more porous structure and a higher water flux for those membranes, which were prepared with 13\ua0wt.% EPVC; while, for those which were fabricated with 15\ua0wt.% polymer, an opposite trend was observed