الفهرس 
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Abstract
The expansion of aquaculture farms was with factor of 5.4% increase in fish production, which brought the total amount produced to 2.0 million tonnes in 2019 from 1.90 million tonnes in 2018 (CAPMAS, 2021). The problems of current study were decrease the dissolved oxygen levels below allowable limits, endangering aquaculture and increasing mortality. Additionally, semi-intensive earthen aquaculture uses a much of water. In addition, traditional methods of aeration produce substantial emissions. The aim of the study was to improve the water quality of aquaculture in earthen ponds then evaluating fine bubbles aeration tube method and determine the optimum operational conditions. The experiment was conducted at an earthen semi-intensive private aquaculture farm in Kafrelshikh governorate, Egypt on season 2021-2022 (25th Nov 2021 – 19th Jan 2022). Also, applicate the optimum parameters at semi-intensive aquaculture greenhouse comparing with traditional water change system and measuring fish indicators (weight gain, feed conversion ratio, specific growth rate, water footprint and biological analysis), water indicators (dissolved oxygen, total ammonia nitrogen, temperature for air and water, total dissolved solids and pH). In addition to that estimation the aquaculture environmental impact of carbon and water footprints and biological impact. V.1 Pre-experiment variables under study were five air flow rates (0.554, 0.969, 1.246, 1.523 and 1.8 m3.h-1), three depths for aeration tube (0.3, 0.5 and 0.7 m from water surface), three inner diameters for tubes (11, 13 and 16 mm) and two shapes of design (longitudinal and circular). V.1.1 Effect of fine bubbles tubes aeration on water turbidity Values of secchi disk clarity and air flow rates has an inverse relationship, so values of secchi disk clarity decreased with increase of air flow rates under all operational conditions. Also, results showed that an inverse relationship conducted for values of secchi disk clarity and depth from water surface, so values of secchi disk clarity decreased with increase of depth from water surface under all operational conditions. While, values of secchi disk clarity increased with increase of thickness of wall tube. As, there a positive relationship between secchi disk clarity and thickness of wall tube. Changing design shape from longitudal to circular lead to decrease values of secchi disk clarity. The maximum value of secchi disk clarity was 41 cm under operational parameters of 0.554 m3.h-1 for air flow rate, 0.30 m for depth from water surface, 7 mm for tube wall thickness and longitudinal shape. The minimum value of secchi disk clarity was 7 cm under operational parameters of 1.8 m3.h-1 for air flow rate, 0.7 m for depth from water surface, 4 mm for tube wall thickness and circular design shape. Permissible limits for variables under study were three air flow rates (0.554, 0.969 and 1.246 m3.h-1), three depths for aeration tube (0.3, 0.5 and 0.7 m from water surface), three inner diameters for tubes (11, 13 and 16 mm) and two shapes of design (longitudinal and circular). V.1.2 Effect of fine bubbles tubes aeration method on oxygen productivity indicators The maximum value of oxygen mass transfer coefficient was 11.581 h-1 under operational parameters of 0.554 m3.h-1 for air flow rate, 0.70 m for depth from water surface, 7 mm for tube wall thickness and circular design shape. The minimum value of oxygen mass transfer coefficient was 3.899 h-1 under operational parameters of 1.246 m3.h-1 for air flow rate, 0.30 m for depth from water surface, 4 mm for tube wall thickness and longitudinal design shape. The increase of air flow rate from 0.554 to 1.246 m3.h-1 leaded to decrease at oxygen mass transfer coefficient with 17.38 % (from 5.425 to 4.482 h-1) at depth from water surface of 30 mm, tube wall thickness of 4 mm and circular design shape. The increase of depth from water surface from 0.3 to 0.7 m resulted in increase at oxygen mass transfer coefficient with 53.53 % (from 5.425 to 8.329 h-1) at air flow rate from 0.554 m3.h-1, tube wall thickness of 4 mm and circular design shape. The increase of tube wall thickness from 4 to 7 mm resulted in increase at oxygen mass transfer coefficient with 37.82 % (from 5.425 to 7.477 h-1) at air flow rate from 0.554 m3.h-1, depth from water surface of 0.3 m and circular design shape. The changing of shape design from circular to longitudinal led to decrease of oxygen mass transfer coefficient with 3.3 % (from 5.425 to 5.246 h-1) at air flow rate from 0.554 m3.h-1, depth from water surface of 0.3 m and tube wall thickness of 4 mm. The optimum operational conditions were air flow rate of 0.554 m3.h-1, inner diameter of 11 mm, 0.7 m tube depth from water surface and circular design shape, whereas oxygen mass transfer coefficient was 11.58 h-1, standard aeration efficiency was 2.66 kg.O2/kW.h.m of tube. V.2 Main experiment stage results The main experiment results include water quality and fish growth indictors. V.2.1 Water quality indicators Water quality indicators included water dissolved oxygen, water total ammonia nitrogen (TAN), water total dissolved solids (TDS), water pH and temperature of water and air. V.2.1.1 Water dissolved oxygen The results showed that fine bubbles aeration method give best values for dissolved oxygen compared with traditional aeration method at all experimental replicates. The maximum mean value for dissolved oxygen was 91% of saturation obtained at fine bubbles aeration method. Also, the minimum mean value for dissolved oxygen was 15% of saturation obtained at traditional aeration method. V.2.1.2 Water total ammonia nitrogen The maximum mean value for total ammonia nitrogen was 4.89 mg/l obtained at traditional water change aeration method. Also, the minimum mean value for total ammonia nitrogen was 0.32 mg/l obtained at fine bubbles aeration method. V.2.1.3 Water temperature The maximum and minimum mean values for air temperature in greenhouse were 39.9 and 7.3 °C, respectively. The maximum and minimum mean values for air temperature out greenhouse were 33.8 and 6.2 °C, respectively. The maximum and minimum mean values for water temperature in fine bubbles treatment were 31.4 and 5 °C, respectively. The maximum and minimum mean values for water temperature in traditional water change treatment were 30.9 and 5 °C, respectively. V.2.1.4 Water total dissolved solids (TDS) The obtained results showed that total dissolved solids (TDS) mean values in fine bubbles treatment were higher than those at traditional water change treatment at all days and times on the day of the experiment. The measurement time hasn’t a significant effect total dissolved solids (TDS) values. The minimum and maximum mean values for total dissolved solids (TDS) in fine bubbles treatment were 1.610 and 1.7 mg/l, respectively. The minimum and maximum mean values for total dissolved solids (TDS) in traditional water change treatment were 1.610 and 1.647 mg/l, respectively. V.2.1.5 Water pH The measurement time has a little significant effect on pH values, so it has little increase at 3 p.m. The minimum and maximum mean values for pH in fine bubbles treatment were 7.3 and 8.1, respectively. The minimum and maximum mean values for pH in traditional water change treatment were 6.5 and 7.6, respectively. V.2.2 Fish growth indicators Fish growth indicators consists of fish weight gain, FCR and SGR. V.2.2.1 Fish weight gain Results declared that there an increase in weight gain for the two treatments along the experiment, however its ratio in F.B.T. more than in W.C.T. It’s conducted that the maximum weight gain for F.B.T. was 346.4 g, while it was 308.1 g for W.C.T. V.2.2.2 Feed conversion ratio (FCR) and survival rate The best FCR value was 1.181 and obtained at the seventh week for F.B.T, while the best value for W.C.T was 1.58 and obtained at the fifth week. Also, the survival rate values were 98.89 and 91.11 % for F.B.T. and W.C.T., respectively. V.2.2.3 Specific growth rate (SGR) The maximum SGR value was 1.96 which obtained at the seventh week for F.B.T, while the minimum value was 0.86 obtained at the fifth week for W.C.T. SGR value influence with other conditions as temperature for example. Hence, SGR values increase with increase in water temperature. V.3 Environmental impact stage Environmental impact at three partitions of carbon footprint, water footprint and biological impact. V.3.1 Carbon footprint estimation Carbon footprint estimation for three stages of pre-farming, farming and post-farming. V.3.1.1 Pre-farming EI stage Results showed that at Pre-farming EI stage, the extruded feed for the third factory has the maximum EI with 1.283 kgCO2e/kg feed and the pelleted feed at the first factory has the minimum EI with 1.043 kgCO2e/kg feed. V.3.1.2 Farming EI stage At this stage results obtained showed that X farm had the maximum EI value compared to Z and Y farm with 3.131, 2.05 and 2.036 kg CO2e/kg.fish, respectively. This was due to high amount of feed used with high value of FCR. V.3.1.3 post-farming EI stage At this stage, the data revealed that Y farm had the highest EI value, with 0.222 kg CO2e/kg.fish, while Z and X farms EI values were 0.18 and 0.13 kg CO2e/kg.fish, respectively. Z farm had the greatest ice manufacturing energy EI value of 0.0079 kg.CO2e/kg.fish, while X farm had the lowest value of 0.0035 kg CO2e/kg.fish. All the three farms had the same value for fish HDPE Boxes EI with 0.00063 kg.CO2e/kg.fish. V.3.2 Water footprint estimation The results showed that 1m3 of water can produce 153.97 g of fish at F.B.T. compared with 42.765 g at W.C.T. (equivalent 6.498 m3/kg for F.B.T and 23.386 m3/kg for W.C.T.). V.3.3 Biological impact Biological indicators estimated for blood, blood bio-chemical, digestive enzymes, anti-oxidant enzymes and serum bio-chemical parameters. V.3.3.1 Blood parameters Aeration method has a significant effect on red blood cells (Rbcs) where P value was 0.033. Also, a significant effect obtained on hemoglobin content (HB) where P value is 0.04. In addition to that, Packed cell volume (PCV) has a significant different at P value of 0.046. On the other hand, there is no significance between replicates mean values of fine bubbles aeration treatment and water change treatment for mean corpuscular volume (MCV), Mean corpuscular Hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) indicators. V.3.3.2 Blood bio-chemical parameters Fine bubbles tube treatment and water change treatment have no significant effect on albumin and lysozyme. While fine bubbles aeration has highest value of total protein by 4.93 g/dl compared with 4.46 g/dl for water change treatment. Also, fine bubbles aeration has highest value of globulin by 3.41 g/dl compared with 2.93 g/dl for water change treatment. V.3.3.3 Digestive enzymes parameters Aeration method has a significant effect on Lipase where P value is 0.049. While fine bubbles tube treatment and water change treatment have no significant effect on Amylas. However, Amylas mean values were 21.047 and 12.307 U/L for fine bubbles aeration and water change treatment, respectively. V.3.3.4 Anti-oxidant enzymes parameters The results showed that fine bubbles tube treatment and water change treatment haven’t a significant effect on superoxide dismutase (SOD), catalase (CAT) and Malondialdehyde (MDA). Also, results showed that mean values for SOD were 8.87 and 8.187 U/gm, CAT were 10.617 and 10.367 U/gm and MDA mean values were 12.93 and 18.367 nmol/g for fine bubbles aeration and water change treatment, respectively. V.3.3.5 Serum bio-chemical parameters The results showed that fine bubbles tube treatment and water change treatment haven’t a significant effect on white blood cells (WBcs), eosinophil, monocyte, lymphocyte, heterophil, glucose, Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), urea, creatinine, cholesterol and triglyceride. However, they have a significant effect on basophil at p of 0.024. Conclusions: Turbidity in water is caused by suspended particles, which might be organic or inorganic. Permissible limits for variables under study were: Three air flow rates of 0.554, 0.969 and 1.246 m3.h-1. Three depths for tube of 0.3, 0.5 and 0.7 m from water surface. Three inner diameters for tubes of 11, 13 and 16 mm. Two design shapes of longitudinal and circular. The maximum value of standard aeration efficiency was 2.66 kg.O2/kW.h obtained at the optimum operational conditions of 0.556 m3.h-1 for air flow rate, 0.70 m for depth from the water surface, 7 mm for tube wall thickness and circular design shape. The best FCR value was 1.181 and obtained at the seventh week for F.B.T, while the best value for W.C.T was 1.58 and obtained at the fifth week. Also, Water footprint was 6.498 m3/kg for F.B.T and 23.386 m3/kg for W.C.T. Whereas, the mean values of the feed conversion ratios were 1.251 and 1.46 for the treatments of fine bubble aeration and aeration by traditional method of changing water, respectively. Farming feed manufacturing stage had the highest EI percentage at total EI for all farms under study with 51.8, 50.33 and 56.6% for X, Y and Z farms, respectively. (X) farm had the highest EI value of 3.265 kg.CO2e/kg fish and 50.917 ton CO2e/season compared with (Z) farm which had the lowest EI value with 2.23 kg.CO2e/kg fish and 38.86 ton CO2e/season. Also, there is a reduction in GHGs emissions with 0.8058 kg.CO2e/kg.fish due to applicate the developed aeration system compared to traditional system.