الفهرس 
INTRODUCTION AND AIM OF THE WORKOnly 14 pages are availabe for public view
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Abstract
Industrial wastewater is any effluent generated from human actions that are affiliated with the raw materials processing and manufacturing. Its disposal has become an important issue due to its adverse impact on aquatic life and the surrounding environment. Industrial wastewater characteristics differ according to the type of industry and the type of industrial process used.
Egypt is facing a rapid degradation in its surface and ground water because of the increase discharge of high polluted domestic and industrial wastewater into its sewerage systems and waterways. Due to the negative impacts of untreated industrial wastewater discharge, regulations are becoming stricter and the treatment of the industrial effluents is nowadays obligatory.
Dairy manufacturing was chosen as a one of those industries whose wastewater effluent is causing a problem for the sewerage system and the public wastewater treatment plant. The dairy wastewater, like most other agro-industries, contains high concentration of organic materials, including carbohydrates, proteins phosphorous, lipids and nitrates which contributes to the high BOD and COD values.
Dairy wastewater is discharged into streams, that can allow rapid decomposition, but it can release strong odor. In addition, dairy wastewater contributes to water eutrophication. Highly nutritious wastewater allows the rapid growth of algae and bacteria, which can consume huge amount of oxygen in the water environment; thereby it results in an anaerobic condition to aquatic animals and plants and finally causes large scale of death. The main aim of this research was to study the efficiency of AOP in the treatment of wastewater generated from dairy factories.
Generally, dairy wastewater is treated through physico-chemical and biological methods. Physico-chemical treatments techniques like coagulation/flocculation, adsorption, and membrane process can get rid of milk protein and fat colloids in the dairy wastewater.
Adsorption with CAC is an efficient technique for the removal of various pollutants from dairy wastewater; however, the high cost of CAC inhibits its large-scale application as an adsorbent. Therefore, there is a need for low-cost alternative adsorbents utilized for effective removal of various pollutants from wastewaters.
Biomass derived ACs have been successfully applied for wastewater treatment to remove various contaminants due to their low cost, high efficiency, ease of synthesis, environmental friendliness, sustainability, and renewability. One of the major contributors to the biomass wastes are fruit wastes. These wastes include banana peels, orange peels, rice husks and coconut husk.
In this study, we prepared AC derived from OP by chemical activation using concentrated sulfuric acid. Physicochemical characterization of the prepared AC was
Summary, Conclusions, and Recommendations.
performed via SEM and FT-IR, The SEM micrographs of AOP showed rough surface with well enlarged pores ranging from 2 µm to 40 µm which indicate successful activation of OP.
Moreover, the adsorption efficiency, adsorption kinetics and adsorption isotherm of AOP was studied using methylene blue dye removal. In our study, seven different initial concentrations of MB (10, 20, 30, 50, 70, 100 and 500 mg/L) were studied to determine their effect on the adsorption capacity of 0.4g AOP/200 mL MB. The adsorption efficiency was represented in decreasing the final concentration of MB (Cf), increase MB percentage removal (a) and increasing of adsorption capacity (q).
The adsorption of MB onto AOP was a very fast process, in case of MB initial concentration 500 mg/L, the adsorption capacity was 135 mg/g after 5 min. and the maximum adsorption capacity was 247.8 mg/g after 1500 min. which indicates a high degree of affinity of the interacting groups on the surface of the activated carbon. Moreover, the contact time needed for MB solutions with initial concentrations of 10 mg/L to reach equilibrium was about 100 min. However, for MB solutions with initial concentrations 500 mg/L longer equilibrium times were reached at 1500 min.
Two kinetic models, pseudo first order and pseudo second order kinetics, were used to study the adsorption dynamics of our AOP. Compared to pseudo first-order rate equation, pseudo-second-order rate equation (R2 = 0.999–1) showed better fitting to the experimental data for all samples. In addition, the experimental qe value (qe,exp) and the calculated qe value (qe,cal) were very close to each other indicating that pseudo-second-order kinetic model was the best fit model for our MB on AOP.
Moreover, two isotherm models (the Langmuir and Freundlich isotherm models) were used to study how the molecules of MB interact with the adsorbent surface. The Freundlich isotherm model yielded a good fit with the R2 value of 0.97. Also, the Kf value was 23.91 and 1/n was 5.27. The high value of 1/n indicates the high adsorbent loading at low concentration, the high affinity between the adsorbate and adsorbent, and heterogeneity of the adsorbent sites.
In phase 2 of our study, the adsorption efficiency of our AOP was studied on an artificial dairy sample to remove any interfering that may result from components other than milk such as detergent and sanitizers that may present in industrial dairy wastewater. Experiments were carried out by adding different doses of AOP (1, 2, 3, 4, 5 and 6 g) to 500 mL of artificial dairy wastewater under constant mixing speed (100 rpm) for different contact time (0.5, 1 and 2.5 h). The maximum %COD removal was reached after 2.5 h at AOP dose of 2 g/L. By increasing the AOP dose gradually the %COD removal remained nearly constant. Then, it started to decrease at AOP dose of 10 g/L. This decrease in % COD removal may be due to the release of soluble organic compounds contained in the plant materials (orange peels) from which AOP was prepared.
The best dose obtained from phase 2 was applied on industrial dairy wastewater for assessment of AOP. In phase 3; industrial dairy wastewater was treated with 2 g/L of AOP for 2.5 h, the results showed COD value of 1134 mg/L meaning that AOP showed % COD removal of 13% only. This may be attributed to the blockage of AOP active sites by curd particles present in dairy wastewater limiting its adsorption capacity and the fact that AC is usually used both as a primary treatment, to facilitate other purification processes, and as the final tertiary stage in the purification of the effluent.
Summary, Conclusions, and Recommendations:
5.2. Conclusions: Based on the findings of the study, the following can be concluded: 1. Wastewater generated from factory was violating decree No. 44/2000 in PO4-3, COD and O&G. 2. characterization of AOP by SEM showed a rough surface with well enlarged pores ranging from 2 to 40 µm, which allowed adsorption process. 3. The AOP shows better performance in removal of MB dye. 4. The adsorption of MB onto AOP was a very fast process, where the % of MB removal was around 70% in the first 5 min. 5. The AOP was fitting with Pseudo second order kinetics model and Freundlich isotherm model. 6. The AOP showed % COD removal of 18.7 % for ADW and 13% for industrial sample. 7. The use of AOP only in the treatment of dairy wastewater could lead to leaching of black color, which increases the COD value causing decrease in the percentage removal efficiency.
5.3. Recommendations: The following recommendations are suggested based on the study results:
1. The AOP is not efficient in treatment of dairy wastewater and can not be used as a single treatment technique. 2. Using AOP in treatment of industrial wastewater from dyeing industry. 5.3.1. Further studies: 1. Studying the efficiency of AOP for real industrial dairy wastewater after filtration to avoid blockage of AOP pores by curd particles present in dairy wastewater which limits the adsorption capacity of AOP. 2. Studying the effect of pH on the percentage COD removal in the treatment of dairy wastewater.
3. Comparing the adsorption efficiency of prepared AOP with CAC in dairy wastewater treatment. 4. Using AC as a primary treatment, to facilitate other treatment processes, or as the final tertiary stage in the treatment of industrial effluent (as a polishing step).