Nabil S. Abuzaid

Coagulation of polymeric wastewater discharged by a chemical factory

Treatment of an emulsified polymeric wastewater was investigated using sedimentation and coagulation. Settleability studies and jar tests were conducted in order to investigate the effect of sedimentation and coagulation on treatment of the wastewater, respectively. The effect of alum, ferric chloride and ferrous sulphate as coagulants on the treatment of samples collected from two different discharged streams was studied. The results of the settleability studies showed that the wastewater of both streams were insettleable. The jar tests revealed that the wastewater of the first stream was best treated when 200 mg/l of ferric chloride were dosed at pH 9. At optimum conditions, the turbidity and COD of the wastewater were reduced by 99.6 and 99.3 per cent, respectively. Alum was found to produce the best results with wastewater of the second stream, when 250 mg/l were used at pH 9. At optimum conditions, turbidity and COD were reduced by 96.3 and 95.9%, respectively. The COD of the treated wastewater is well below the limit set by the regulatory authority, hence, the wastewater can be discharged to the biological treatment plant of the industrial city.

Electrochemical oxidation of phenol using graphite anodes

The effects of current and pH on the electrochemical oxidation of phenol on graphite electrodes is investigated in this study. There was no sign of deterioration of the graphite bed after 5 months of operation. Phenol removal efficiency was a function of the current applied and was around 70% at a current of 2.2 A. The increase of phenol removal efficiency with current is attributed to the increase of ionic transport which increases the rate of electrode reactions responsible for the removal process. The percentage of complete oxidation of phenol increases with current, with a maximum value of about 50%. However, at pH 0.2 it is slightly higher than that at pH 0.5 at all currents. The phenol removal rate increases with increases of current and pH. While the current (CO2) efficiency reaches a maximum value in the current range of 1.0–1.2 A, it increases with an increase of acid concentration. The findings of this study have important implications: While anodic oxidation of phenol on graphite can achieve ac...

Dissolved oxygen effects on equilibrium and kinetics of phenolics adsorption by activated carbon.

Phenol and o-cresol have been shown to undergo oxygeninduced polymerization reactions on activated carbon that enhance their adsorption. Four different levels of dissolved oxygen (DO) were involved in the equilibrium and kinetics studies undertaken. It was found that for both phenol and o-cresol, the adsorptive capacities increase with the increase in DO concentration. The quantities of dimers and trimers formed on the carbon surface were a function of the DO level. Phenol recovery efficiencies around 70% and 25% were found for anoric and oxic isotherms, respectively. The additional capacity attained under oxic conditions was limited by the masses of DO and granular activated carbon (GAC) in the test environment

Ground water coagulation using soluble stainless steel electrodes

Abstract This study dealt with colloids separation from ground water in the Eastern Province of Saudi Arabia. The water was found to have a conductivity of 4400 μs/cm and chloride and sulfate concentrations of 834 and 550 mg/l, respectively. The turbidity of the water was increased to 76 nephlometric turbidity unit (NTU) by the addition of bentonite. The efficiency of using soluble stainless steel electrodes for the in-situ formation of ferric hydroxide has been investigated. The electrical current input was found to be inversely proportional to the residual turbidity in the test water. At a contact time of 5 min and a natural chloride content, the highest turbidity removal efficiency of 95% was achieved at a current of 1 A. When the current was reduced to 0.5 A and the contact time was increased to 10 min, the residual turbidity was reduced from 4.0 to 1.6 NTU. Furthermore, similar turbidity removals were achieved at a much shorter contact time (2 min) when 1 g/l sodium chloride was added to the test water. Due to the importance of pH variation with regard to coagulation, the phenomenon of voltage-induced hydrogen evolution was investigated as well. While the solutions final pH increased with the increase in current and contact time, it decreased with the increase in sodium chloride concentration.

The influence of residence time on the anodic oxidation of phenol

Abstract The anodic oxidation of phenol using porous graphite was investigated in this study. The experiments were designed so that the effect of residence time at different currents on phenol oxidation would be elucidated. Phenol removal efficiency was a function of the applied current and the residence time and was around 50% at a current of 2.0 A and a residence time of 35 min. Phenol removal efficiency was found to increase with the increase in current and residence time. An empirical model was developed to predict the effect of flow rate or residence time and current on the phenol removal efficiency. Percentage of phenol completely oxidized, measured by the amount of CO 2 produced, increased with current and residence time and reached 48% at a current of 2 A and a residence time of 23.3 min. It was found that the phenol removal rate increases with the decrease in residence time. Maximum current (CO 2 ) efficiencies were achieved at currents of 1.0 and 1.25 A at residence times of 35 and 23.3 min, respectively. Residence time was identified as an important parameter in affecting removal efficiency and complete detoxification of phenol.

Electrochemical treatment of phenolic wastewater: Efficiency, design considerations and economic evaluation

Abstract Anodic oxidation of phenol at a graphite electrode has shown good treatment efficiency. The removal efficiency was a function of the current applied, with around 70% phenol removal efficiency at a current of 2.2 A. After about 5 months of operation, there was no sign of deterioration of the graphite bed. An empirical relationship was developed relating phenol removal efficiency to the current. The relationship showed excellent prediction of the experimental data. Furthermore, a methodology for calculating the cell capacity was developed. The relation between the cell capacity and phenol residual concentration was modelled using a non linear model. Preliminary design procedure for the electrochemical cell was illustrated and the designs results for nine different wastewater conditions were tabulated. Economic evaluation of the process under different scenarios was presented and compared with other processes.

Electrochemical Treatment of Nitrite Using Stainless Steel Electrodes

The efficiency of nitrite removal in an electrochemical cell was investigated in this study using stainless steel electrodes. The experiments were designed to study the effects of current input, volume of the solution, initial pH, and number of electrodes on removal of nitrite at a concentration typical to aquaculture system effluents. Current variation causes opposite trends, while an increase in current would increase the oxidizing efficiency of the system, the voltage induced increase in pH due to hydrogen evolution would decrease the efficiency of the oxidizing agent formed. However, the highest nitrite removal was achieved at a current of 2 A and a complete removal was attained after a duration of ten minutes. A first order reaction model was developed to predict the effect of current on nitrite removal. The energy consumption was directly proportional to the initial pH and the solution volume, while it was inversely proportional to the number of electrodes.

Removal of bentonite causing turbidity by electro‐coagulation

Abstract The efficiency of electro‐coagulation as a turbidity removal process has been investigated using bentonite as a turbidity source. The influence of certain operational parameters such as current input, contact time, electrolyte concentration, and initial turbidity on the coagulation efficiency were studied. The process was found to achieve excellent turbidity removals. The lowest residual turbidities were 0.5 and 0.75 NTU for the samples with initial turbidities of 112 and 52 NTU, respectively. This was obtained at a current of 0.5 A, a contact time of 5 minutes, and a calculated dissolved iron concentration of 10.8 mg/l. At a constant current of 0.5 A, a reduction in the contact time from 5 to 2 minutes in the case of turbidity level 1 (52 NTU) and from 5 to 1 minute in the case of turbidity level 2 (112 NTU) resulted in better turbidity removals. The optimal operational parameters for turbidity level 1 are a current of 0.5 A, a contact time of 2 minutes and an NaCl concentration of 2 g/l resulti...

Effect of solution pH on the kinetics of phenolics uptake on granular activated carbon

Abstract The impact of solution pH on the kinetics of adsorption and adsorption-reaction combination of phenol and o-cresol on Granular Activated Carbon (GAC) was evaluated at room temperature (21°C). Batch experiments were performed under oxic and anoxic conditions at pH values of 3, 7, and 11. The results showed that the equilibration time forphysical adsorption increased with the increase in pH and occurred in the time range of (7.5–11) days for the adsorption-reaction combination (oxic cases). The polymerization reactions lagged by about 10 h under all of the pH values. Diffusivity coefficients in the oxic cases increased inversely with pH while the highest difference between oxic and anoxic diffusivities was observed at neutral pH. The homogeneous surface diffusion model (HSDM) predicted accurately the anoxic batches and deviated from the oxic data under all pH conditions. Under controlled dissolved oxygen and pH conditions, the isotherm and batch equilibrium capacities matched with maximum deviation of 4%. The effect of solution pH on the rate of the DO-induced enhancement was found to follow a simplified form of self retardant reaction model. The aforementioned model showed strong predictive capability for the formation of polymers with time.

Modeling of the temperature variation effects on the polymerization reactions of phenolics on granular activated carbon

The effect of temperature variation on the kinetics of adsorption and adsorption-reaction combination of phenol and o-cresol on granular activated carbon (GAC) was evaluated throughout this study. Batch experiments were performed under oxic and anoxic conditions at temperatures of 8, 21, and 35°C. The results showed that the equilibration time for physical adsorption increased with the decrease in temperature and occurred in the time range of 7.5-11 days for the adsorption-reaction combination (oxic cases). The polymerization reactions lagged by about 10 hours under all of the temperature values. Diffusivity coefficients in the anoxic cases increased proportionally with temperature, with the highest difference between oxic and anoxic diffusivities at 35°C. The homogeneous surface diffusion model (HSDM) accurately predicted the anoxic batches and deviated from the oxic data. Temperature increases the adsorption and polymerization reaction rates, and thus the predictivity of the HSDM for both oxic and anoxic batches improves. Under controlled dissolved oxygen (DO) and temperature conditions, the isotherm and batch equilibrium capacities matched with a maximum deviation of 4%. The effect of temperature on the rate of the DO-induced enhancement was found to follow a self-retardant reaction model. The developed model showed strong predictive capability for the temporal formation of polymers.