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Shrimp and fish pond soils: processes and management
- Aquaculture
, 2003
"... The pond bottom soil and the accumulated sediments are integral parts of ponds. Concentrations of nutrients, organic matter and microorganism density in the pond bottom are several orders of magnitude greater than in the water. The accumulation of organic sediments may limit pond intensification. Th ..."
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The pond bottom soil and the accumulated sediments are integral parts of ponds. Concentrations of nutrients, organic matter and microorganism density in the pond bottom are several orders of magnitude greater than in the water. The accumulation of organic sediments may limit pond intensification. The intensive organic matter degradation at the pond bottom and high sediment oxygen demand exceeds the oxygen renewal rate. This leads to the development of anoxic conditions in the sediments and at the sediment–water interface. A series of anaerobic processes, affected by the redox potential of the system, are taking place. A large number of potentially toxic materials are generated. Among those are organic acids, reduced organic sulfur compounds, reduced manganese and sulfides. Shrimp, as animals that normally live on or near the bottom, are exposed to conditions on the pond bottom. Exposure to toxic materials endanger the well being of the cultured shrimp. Reduced feeding, slower growth, mortality and possibly higher sensitivity to disease are reported. The rational use of aerators to minimize the area of sludge accumulation, construction of ponds to trap sludge, stirring sediments, chemical poising of the redox system and environmentally accepted treatment and reuse of drained sediments are means to control the conditions at the pond bottom.
Environmental assessment of channel catfish Ictalurus punctatus farming in Alabama
- Journal of the World Aquaculture Society
, 2000
"... Abstract An environmental assessment was made of Alabama channel catfish Ictalurus punctahrs farming which is concentrated in the west-central region of the state. There are about 10,OOO ha of production ponds with 10.7% of the area for fry and fingerlings and 89.3% for food fish. Food fish product ..."
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Abstract An environmental assessment was made of Alabama channel catfish Ictalurus punctahrs farming which is concentrated in the west-central region of the state. There are about 10,OOO ha of production ponds with 10.7% of the area for fry and fingerlings and 89.3% for food fish. Food fish production was about 40,800 tons in 1997. Watershed ponds filled by rainfall and runoff make up 76% of total pond area. Water levels in many of these ponds are maintained in dry weather with well water. The other ponds are embankment ponds supplied by well water. Harvest is primarily by seine-through procedures and ponds are not drained frequently. The main points related to Alabama catfish farming and environment issues are as follows: 1) catfish farming in Alabama is conservative of water, and excluding storm overflow, about two pond volumes are intentionally discharged from each pond in 15 yr; 2) overflow from ponds following rains occurs mostly in winter and early spring when pond water quality is good and stream discharge volume is high; 3) total suspended solids concentrations in pond effluents were high, and the main sources of total suspended solids were erosion of embankments, pond bottoms, and discharge ditches; 4) concentrations of nitrogen and phosphorus in effluents were not high, but annual effluent loads of these two nutrients were greater than for typical row crops in Alabama; 5 ) ground water use by the industry is about 86,000 m3/d, but seepage from ponds returns water to aquifers; 6) there is little use of medicated feeds; 7) copper sulfate is used to control blue-green algae and off-flavor in ponds, but copper is rapidly lost from pond water; 8) although sodium chloride is applied to ponds to control nitrite toxicity, stream o r ground water salinization has not resulted from this practice; 9 ) fertilizers are applied two or three times annually to fry and fingerling ponds and occasionally to grow-out ponds; 10) hydrated lime is applied occasionally a t 50 to 100 k g h a but this does not cause high pH in pond waters o r effluents; 11) accumulated sediment removed from pond bottoms is used to repair embankments and not discarded outside ponds; 12) sampling above and below catfish pond outfalls on eight streams revealed few differences in stream water quality; 13) electricity used for pumping water and mechanical aeration is only 0.90 kWWkg of production; 14) each metric ton of fish meal used in feeds yields about 10 tons of dressed catfish. Reduction in effluent volume through water reuse and effluent treatment in settling basins or wetlands does not appear feasible on most farms. However, some management practices are recommended for reducing the volume and improving the quality of channel catfish pond effluents .
Oxidation ditch process using curved blade rotor as aerator
- Int. J. Environ. Sci. Tech
, 2009
"... S. B. Thakre et al. AB STRACT: Oxidation ditch process is used to treat the municipal and domestic sewage. The untreated sewage generates fouling smell, harmful bacteria, etc. which is hazardous for public health and degrades the environment by librating noxious gases. This paper examines the use o ..."
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S. B. Thakre et al. AB STRACT: Oxidation ditch process is used to treat the municipal and domestic sewage. The untreated sewage generates fouling smell, harmful bacteria, etc. which is hazardous for public health and degrades the environment by librating noxious gases. This paper examines the use of curved blade aerator for oxidation ditch process. The rotor, which controls the aeration, is the main component of the aeration process. Therefore, the objective of this study is to find out the variations in overall oxygen transfer coefficient and aeration efficiency for different configurations of aerators by varying the parameters like speed of aerator, depth of immersion and blade tip angles so as to yield higher values of overall oxygen transfer coefficient and aeration efficiency. Four aerators of different configuration were developed and fabricated in the laboratory and were tested for above mentioned parameters. A mathematical model is developed for predicting the values of k L a and aeration efficiency which has R 2 values of 0.97 and 0.99 for experimentally determined and calculated values. In laboratory studies, the optimum value of overall oxygen transfer coefficient and aeration efficiency were observed to be 10.33/h and 2.269 kg O 2 /kWh for aerator speed of 48 rpm, 5.5 cm depth of immersion and 47 o blade tip angle for curved blade aerator.
INTERNATIONAL JOURNAL OF ENGINEERING, SCIENCE AND
"... Design characteristics of Curved Blade Aerator w.r.t. aeration efficiency and overall oxygen transfer coefficient and comparison with CFD modeling ..."
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Design characteristics of Curved Blade Aerator w.r.t. aeration efficiency and overall oxygen transfer coefficient and comparison with CFD modeling
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"... Abstract—During the past decade, pond aeration systems have been developed which will sustain large quantities of fish and invertebrate biomass. Dissolved Oxygen (DO) is considered to be among the most important water quality parameters in fish culture. Fishponds in aquaculture farms are usually loc ..."
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Abstract—During the past decade, pond aeration systems have been developed which will sustain large quantities of fish and invertebrate biomass. Dissolved Oxygen (DO) is considered to be among the most important water quality parameters in fish culture. Fishponds in aquaculture farms are usually located in remote areas where grid lines are at far distance. Aeration of ponds is required to prevent mortality and to intensify production, especially when feeding is practical, and in warm regions. To increase pond production it is necessary to control dissolved oxygen. Artificial intelligence (AI) techniques are becoming useful as alternate approaches to conventional techniques or as components of integrated systems. They have been used to solve complicated practical problems in various areas and are becoming more and more popular nowadays. This paper presents a new design of diffused aeration system using fuel cell as a power source. Also fuzzy logic control Technique (FLC) is used for controlling the speed of air flow rate from the blower to air piping connected to the pond by adjusting blower speed. MATLAB SIMULINK results show high performance of fuzzy logic control (FLC). Keywords—aeration system, Fuel cell, Artificial intelligence (AI) techniques, fuzzy logic control
Mathematical Modeling and Neural Network Control for Dissolved Oxygen
"... Abstract-Dissolved oxygen (DO) is considered as one of the most important aspect of aquaculture. It is needed by fish to respire and perform metabolic activities. Thus low levels of dissolved oxygen are often linked to fish kill incidents. On the other hand, optimum levels can result to good growth, ..."
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Abstract-Dissolved oxygen (DO) is considered as one of the most important aspect of aquaculture. It is needed by fish to respire and perform metabolic activities. Thus low levels of dissolved oxygen are often linked to fish kill incidents. On the other hand, optimum levels can result to good growth, thus result to high production yield. To increase pond production it is necessary to control dissolved oxygen. Artificial intelligence (AI) techniques are becoming useful as alternate approaches to conventional techniques or as components of integrated systems. They have been used to solve complicated practical problems in various areas and are becoming more and more popular nowadays. This paper presents a new design of diffused aeration system using fuel cell as a power source. Mathematical modeling of dissolved oxygen presents in the pond over the day and the fuel cell stack modeling are also presented. Artificial intelligence control techniques are used for controlling the speed of air flow rate from the blower to air piping connected to the pond through control blower speed. MATLAB SIMULINK results show the neural network control (NNC) offer high performance of the system.
Marine finfish aquaculture in Europe is dominated by two major
, 2012
"... tu nv J.G. Ferreira a,⁎, C. Saurel a, J.M. Ferreira b,c s-Monte ..."
Evaluation of Bacterial Amendments for Improving Water Quality in Alabama Catfish Ponds
, 2015
"... ii Four sets of experiments were conducted to evaluate the potential efficacy of bacterial amendments for improving water quality in channel catfish ponds. First, the effects of 12 bacterial amendments from eight companies on reducing total ammonia nitrogen, nitrite nitrogen and organic matter conce ..."
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ii Four sets of experiments were conducted to evaluate the potential efficacy of bacterial amendments for improving water quality in channel catfish ponds. First, the effects of 12 bacterial amendments from eight companies on reducing total ammonia nitrogen, nitrite nitrogen and organic matter concentration in polluted pond water were evaluated in an environmentally controlled room. Then, a selected bacterial amendment (Waste & Sludge Reducer-WAS) was evaluated in channel catfish ponds at the E. W. Shell Fisheries Center. The third set of experiments was to evaluate selected bacterial amendments (Aqua PE and Oxyless) in channel catfish ponds with ammonium sulfate addition at the E. W. Shell Fisheries Center. The final set of experiments was to evaluate the efficacy of the bacterial amendment (Aqua PE) on water quality in Alabama commercial catfish ponds. Concentrations of total ammonia nitrogen (TAN), nitrite nitrogen (NO2 ˉ–N) and organic matter (as estimated from oxygen demand) in untreated water naturally decreased with time during 16 days. No large improvements were observed in accelerating nitrification or organic matter oxidation from the use of bacterial amendments in the laboratory study. There were no differences (P>0.05) in total bacterial count after treatment with WAS on most of the days between May and September. Few differences (P<0.05) were observed in pH and concentrations of POM, Cha a, COD, SCOD, TAN and NO2
