الفهرس 
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Abstract
Industrial wastewater are effluents 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.
Lubricating grease 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. Lubricating grease is an essential requirement for the industrial sector to enhance durability, dependability, and efficiency of equipment. It is a solid or semi-solid product. It contains around 90% of additives, base oil and soap or other thickening agents. Type of thickeners is considered an important factor that determine grease characteristics. These thickeners are classified into groups according to their nature and interaction with the dispersion medium. These groups include polymorphic, non-polymorphic and heat resistant organic and inorganic thickeners.
Grease manufacturing process itself results in small amount of wastewater highly concentrated with COD. Generally, the most waste loading occurs when the process units are washed as this generates oil and soap to be discharged in sewer pipes as oily wastewater. In case of calcium base soap grease production; the conversion of sodium base soap to a calcium base soap is a process which generates a relatively large quantity of sodium chloride and emulsified oils. The main aim of this research was to study the treatability of wastewater generated from lubricating grease factories.
Three treatment methods were investigated for their efficiency of COD removal. The first one was coagulation technique followed by DAF. Second, adsorption treatment using two forms of modified barley straw: Cationic Surfactant Modified Barley Straw (CSMBS) and Fabric Softener Modified Barley Straw (FSMBS) was tested. The last treatment method was the anaerobic decomposition.
Coagulation is the process of making contact between chemical and colloidal particles and producing micro-flocs. This process depends on choosing the proper chemical, dosages and proper pH to reach high performance. After coagulation, a DAF unit was used to remove the flocs by floatation. This process is mainly affected by coagulation chemistry and retention time.
In this study, by using Jar- Test experiment, the adequate combination of pH value, coagulant dose and the DAF process time which leads to a high level of COD level removal. According to the results, coagulation followed by DAF process was able to remove about 63% of COD by using: a coagulant dose 700 mg, at pH level equals to 13, a fixed flash mixing equals to 300rpm/3min, a fixed slow mixing of about 50 rpm/15 min and DAF retention time equals to 20 min.
Adsorption is one of the methods used for removing emulsified oils and organic matters from industrial wastewater. Yet, not all of the adsorbents acquire good adsorption capacities and may need long time for a fruitful adsorption process. Thus, there is a need for a modification for these adsorbents such as cationic surfactants. Using fabric softeners in this study was tested for its capability for enhancement the adsorbent effectiveness.
The adsorption process was carried out in a jar test by mixing modified barley straw and the wastewater at a speed 150 rpm. Three tests were carried out to obtain the optimum level of: modified barley straw dose, pH, Time of mixing; this was done by changing one of those items while fixing the other two. The results of the above tests showed that the Adsorption process by using cationic surfactant modified barely straw was able to remove about 65% of COD while in case of using a fabric softener it removed about 60%. This indicated that there was no significant difference between the two adsorption methods as the optimum conditions and the percentage of COD removal were almost the same.
In the adsorption process for wastewater treatment, the conditions of the regeneration or recovery have to be optimized to enhance the life time of the adsorbents in order to improve its uses in the adsorption- desorption cycles and to lessen the adsorbent structure damage that could happen in the cycle to avoid the loss of mass and active sites. At the end of the adsorbents operational life cycle, it should be disposed. The disposal of the adsorbents is considered an important aspect to reduce the environmental impact generated from solid waste. There are two conventional methods for adsorbents disposal: incineration and landfill.
Anaerobic digestion involves a set of processes in which microorganisms decompose biodegradable materials without any oxygen. These processes depend on the existence of anaerobic bacteria which survive only when consuming the bounded molecule oxygen available in compounds like nitrates (NO3) and sulphates (SO4). A trial experiment was performed to identify the suitable anaerobic conditions which result in high percentage of COD removal. Four samples (pure industrial wastewater, industrial wastewater mixed with domestic wastewater from the factory, industrial wastewater mixed with wastewater from WWTP and finally industrial wastewater mixed with ship fouling) were left under anaerobic condition. The percentage of COD removal was about 8.6%, 23.8%, 46.7% and 65.7% respectively.
In this study, ship fouling, containing salt- tolerant bacteria strain and full of nutrients, was evaluated for its capability of enhancing the anaerobic decomposition of grease manufacturing wastewater. Ship fouling is defined as “the undesirable accumulation of micro-organisms, algae and animals on artificial surfaces immersed in seawater”. The fouling communities in the Harbours of Alexandria were investigated in many studies. The fouling community was recorded to be mainly consisted of Algae, Hydrozoa, Bryozoa, Polychaeta, Girrpedia, Amphipoda, Ascidiacea and Isopods species.
Ship fouling is considered an economic problem all over the world which performs billions of dollars a year to the universal economy because of the high cost and the short lifetime of metal-based anti-fouling paints. It increases the hull roughness which upsurges the frictional resistance and the fuel consumption and decreases the top speed and range. Therefore, ship fouling recovery for the sake of applying it on treatment methods will help in solving the problem.
According to the results it can be stated that the optimum ship fouling dose level needed for anaerobic treatment enhancement was 75g/l which removed about 81% of COD. When the dose increased, the efficiency diminished. In this research, the anaerobic treatment was followed by three treatment methods: Coagulation followed by DAF, coagulation followed by sedimentation and aeration to check the efficiency of each of them for COD removal. It was detected from the results that the aeration was the best treatment can be used after anaerobic decomposition as it removed about 35% of the remainder COD.
Cost Effectiveness Analysis (CEA) is the most common type of economic evaluation used. There are two main factors that should be considered when deciding which appropriate in-site wastewater treatment unit to be used: the efficiency of the unit and the cost. Cost effectiveness can be also determined by using the cost effectiveness plane diagram generally used to present Incremental Cost Effectiveness Ratio (ICER) of different alternatives graphically as a combination of the cost and the outcome of the treatment method. After applying cost effectiveness analysis in this study, it was found that the best alternative in the term of cost effectiveness was adsorption method using CSMBS. The worst alternative was coagulation technique followed by DAF, while anaerobic treatment was potentially acceptable which means that decision makers can consider it, especially because of its high effectiveness and methane generation.
Based on the results obtained, the study concluded that Coagulation technique followed by DAF was found to be able to remove 63% of COD. This efficiency was obtained by using 700mg/l of ferric chloride, pH value of 13, flash mixing of about 300 rpm/3min, slow mixing of 50 rpm/15 min and finally by DAF retention time equals to 20 min. This method was found to be able to break about 99% of the emulsified oils and turned it into free oils.
It was discovered that adsorption process by using CSMBS had the ability to remove about 65% of COD. The optimum conditions for achieving this were by using a dose of about 20 g/l, pH value of 13, 150 rpm of mixing speed and about 30 min for the contact time. On the other hand, using FSMBS was able to remove about 60% of COD. This was done by using a quantity of 25 g/l, pH value of 11 and mixing speed of about 150 rpm for a contact time of 25 min. It was also found that conventional anaerobic decomposition was very weak as high salinity adversely affect the methanogenic microorganisms in the anaerobic treatment. Anaerobic decomposition enhanced by 75g/l dose of ship fouling was capable of removing about 81% of COD. Aeration after the anaerobic treatment could remove about 35% of the remainder COD.
Finally, it is recommended to combine coagulation technique followed by DAF with adsorption process in order to enhance the efficiency of COD removal, to identify the anaerobic bacteria found in ship fouling for better understanding of ship fouling enhancement of anaerobic decomposition, and to conduct a modeling using a suitable statistical method to determine optimum conditions needed for grease manufacturing wastewater treatment.