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111.
Performance of a closed recirculating system with foam separation, nitrification and denitrification units for intensive culture of eel: towards zero emission 总被引:10,自引:0,他引:10
Yoshihiro Suzuki Toshiroh Maruyama Hiroyuki Numata Hajime Sato Makio Asakawa 《Aquacultural Engineering》2003,29(3-4):165-182
The development of a closed recirculating aquaculture system that does not discharge effluents would reduce a large amount of pollutant load on aquatic bodies. In this study, eel were reared in a closed recirculating system, which consisted of a rearing tank, a foam separation unit, a nitrification unit and a denitrification unit. The foam separation unit has an inhalation-type aerator and supplies air bubbles to the rearing water. The growth of eel, which were fed a commercial diet, was satisfactory, with gross weight increases of up three times in 3 months. The survival rate under the congested experimental conditions was 91%. The foam separation unit maintained oxygen saturation in the rearing water at about 80%. Furthermore, fine colloidal substances were absorbed on the stable foam formed from eel mucus and were removed from the rearing water by foam separation. Ammonia oxidation and the removal of suspended solids were accomplished rapidly and simultaneously in the nitrification unit. The ammonia concentration and turbidity were kept at less than 1.2 mg of N per litre and 2.5 units, respectively. When the denitrification process was operated, nitrate that accumulated in the rearing water (151 mg of N per litre) was reduced to 40 mg of N per litre. The sludge was easily recovered from the nitrification and denitrification tanks, and the components were found suitable as compost. Based on these results, the intensive aquaculture of freshwater fish such as eel can be achieved using a closed recirculating system without emission. 相似文献
112.
北海市瓜菜大棚设施栽培现状与发展对策 总被引:1,自引:1,他引:0
从规模、新技术应用、栽培模式、效益等方面阐述了北海市瓜幕大棚设施栽培的现状,同时分析了存在的问题,并针对现状和存在的问题提出了政策扶持、创建品牌、强化培训、加大投入和加强产品质量检测等发展对策,旨在促进大棚设施栽培产业的健康可持续发展. 相似文献
113.
Simulation of transpiration, drainage, N uptake, nitrate leaching, and N uptake concentration in tomato grown in open substrate 总被引:3,自引:0,他引:3
M. Gallardo J.S. Rodríguez M.D. Fernández J.J. Magán 《Agricultural Water Management》2009,96(12):1773-1784
Free-drainage or “open” substrate system used for vegetable production in greenhouses is associated with appreciable NO3− leaching losses and drainage volumes. Simulation models of crop N uptake, N leaching, water use and drainage of crops in these systems will be useful for crop and water resource management, and environmental assessment. This work (i) modified the TOMGRO model to simulate N uptake for tomato grown in greenhouses in SE Spain, (ii) modified the PrHo model to simulate transpiration of tomato grown in substrate and (iii) developed an aggregated model combining TOMGRO and PrHo to calculate N uptake concentrations and drainage NO3− concentration. The component models simulate NO3−-N leached by subtracting simulated N uptake from measured applied N, and drainage by subtracting simulated transpiration from measured irrigation. Three tomato crops grown sequentially in free-draining rock wool in a plastic greenhouse were used for calibration and validation. Measured daily transpiration was determined by the water balance method from daily measurements of irrigation and drainage. Measured N uptake was determined by N balance, using data of volumes and of concentrations of NO3− and NH4+ in applied nutrient solution and drainage. Accuracy of the two modified component models and aggregated model was assessed by comparing simulated to measured values using linear regression analysis, comparison of slope and intercept values of regression equations, and root mean squared error (RMSE) values. For the three crops, the modified TOMGRO provided accurate simulations of cumulative crop N uptake, (RMSE = 6.4, 1.9 and 2.6% of total N uptake) and NO3−-N leached (RMSE = 11.0, 10.3, and 6.1% of total NO3−-N leached). The modified PrHo provided accurate simulation of cumulative transpiration (RMSE = 4.3, 1.7 and 2.4% of total transpiration) and cumulative drainage (RMSE = 13.8, 6.9, 7.4% of total drainage). For the four cumulative parameters, slopes and intercepts of the linear regressions were mostly not statistically significant (P < 0.05) from one and zero, respectively, and coefficient of determination (r2) values were 0.96-0.98. Simulated values of total drainage volumes for the three crops were +21, +1 and −13% of measured total drainage volumes. The aggregated TOMGRO-PrHo model generally provided accurate simulation of crop N uptake concentration after 30-40 days of transplanting, with an average RMSE of approximately 2 mmol L−1. Simulated values of average NO3− concentration in drainage, obtained with the aggregated model, were −7, +18 and +31% of measured values. 相似文献
114.
温室环境控制系统的MPT智能算法 总被引:1,自引:0,他引:1
针对温室环境的大滞后、多输入、多输出、非线性和难以建立数学模型等特点,对传统的PID算法进行改进,并加入自适应控制、模糊控制和专家自整定等智能控制功能,建立了MPT智能控制算法.在论域内用不同控制方式分段控制,当偏差大于某一域值时,根据操态选择模糊控制,不存在抗饱和积分问题,使用模糊控制规则确定输出;当偏差减小到域值以下时,切换转入MPT算法控制,减小响应过程中的超调,并最终消除余差.该算法具有无超调、控制精度高和鲁棒性强等特点.. 相似文献
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118.
赵明宏 《农业机械化与电气化》2009,(3):138-139
介绍后置式大棚卷帘机的基本结构和工作过程,详细说明其安装技术要点,指出其在使用中应注意的事项,并对使用卷帘机和人工卷帘进行经济效益分析,证明使用卷帘机作业具有减轻劳动强度、节约作业成本、提高作业效率、增产增收等优点。 相似文献
119.
以玉米秸秆为原料,利用北方日光温室进行反季栽培双孢蘑菇技术试验。试验结果表明,采用夏季发酵培养料、秋季播种、秋冬季节出菇的反季栽培双孢蘑菇技术模式,与北方气候条件基本吻合,再利用日光温室进行出菇,可减少能源消耗。在日光温室条件下用玉米秸秆作主料栽培双孢蘑菇,每平方米产双孢蘑菇10~15kg,可提高菇农的种植效益。栽培后产生的废料还可肥田和改良土壤理化性状,使生物转化率达40%以上。 相似文献
120.
不同灌溉方式对日光温室青椒生长及产量的影响 总被引:1,自引:0,他引:1
为了确定日光温室内青椒的最适合灌溉技术,在日光温室内分别对青椒进行了滴灌、小管出流和沟灌3种灌溉方式的试验研究,分析了不同灌溉方式对日光温室青椒生长发育的影响。试验结果表明:不同灌溉方式对青椒株高、茎粗均无明显影响;相同阶段所测叶绿素含量,滴灌>小管出流>沟灌,且叶片叶绿素的含量和光合速率呈正相关;用显著性水平α=0.1对各处理产量进行方差分析表明,不同处理对产量有显著影响,青椒产量以滴灌最高,小管出流次之,沟灌最低;通过不同处理比较发现,沟灌、滴灌、小管出流水分生产率分别为16.17、35.13、31.59 kg/m3。故日光温室栽培青椒比较适合采用滴灌方式。 相似文献