Reporting standards for biofilter performance studies

The development of standardized rating and design procedures for biological filters will require that filter performance be evaluated and reported in a standardized manner. This article recommends draft reporting standards for biofilter performance studies. It is important that critical parameters are defined and reported in a standard manner, both in terms of definition, variable names, and units. Depending on the type and scale of an experiment, reporting of certain parameters will be either mandatory or optional. Basic principles of experimental design, statistical analysis, and randomization must be followed. Experimental protocols are recommended to ensure the accuracy of measured or computed parameters. The development of this reporting standard is being organized through the Standards and Reporting Committee of the Aquaculture Engineering Society (AES). It is anticipated that a revised version of these standards will be incorporated into the Guide to Authors for Aquacultural Engineering.     

Nitrification kinetics of biofilm as affected by water quality factors

Various types of fixed film biofilters have been used in recirculating aquaculture systems under different water quality and operating conditions. The effectiveness of the nitrification process can be evaluated by nitrification kinetics. Nitrification in the bacterial film of the biofilter involves physical, chemical and biological processes that are governed by a variety of parameters such as substrate and dissolved oxygen concentrations, organic matters, temperature, pH, alkalinity, salinity and turbulence level. The impacts of these parameters upon nitrification kinetics make predicting the performance of a biofilter for a given application an engineering challenge. Knowing the performance of a biofilter is critical for both designers and managers. This paper summarizes the current knowledge on nitrification kinetics as affected by the aforementioned factors based on literature and the results from the authors’ laboratories. These factors were ranked according to their significance of impact on biofilter nitrification performance. The information presented can be used as a reference for the design and operation of biofilters in recirculating aquaculture systems.     

Utilization of the filter feeder polychaete Sabella

The filter feeder sabellid Sabella spallanzanii Gmelin (Polychaeta, Sabellidae) was proposed as biofilter in the treatment of wastes from intensive aquaculture. The species was previously studied concerning reproductive traits and ecological requirements; moreover, previous laboratory experiments indicated a positive action of its feeding activity on solid removal from water column coupled with an interesting microbiological activity. In the present paper data on settlement and growth rate from a natural population, together with data on the bioremediation activity of an adult population, relative to an experiment conducted in a small fish farm are reported. Results seem to encourage further studies on S. spallanzanii for a future utilization in bioremediation of fish farms with recycled water. Data from natural annual settlement indicated, however, the unreliability in obtaining settlers from natural populations, so that the artificial reproduction of the target species will be one of the main points of further investigations.     

硝化细菌分子生态学研究进展

硝化细菌在促进水域生态系统的氮循环、保持健康水产养殖环境方面发挥着巨大作用。本文分析了硝化细菌分子生态学研究的意义,介绍了硝化细菌的主要种类及其系统进化关系,综述了硝化细菌分子生态学研究进展,并对中国的研究现状进行了分析。结合作者的工作实践,认为中国应加强对水产养殖环境硝化细菌分子生态学研究,为养殖环境的污染防治和微生态制剂的研制等提供理论依据。     

Analysis of nutrient flows in integrated intensive aquaculture systems

This paper analyses nutrient conversions, which are taking place in integrated intensive aquaculture systems. In these systems fish is cultured next to other organisms, which are converting otherwise discharged nutrients into valuable products. These conversions are analyzed based on nitrogen and phosphorous balances using a mass balance approach. The analytical concept of this review comprises a hypothetical system design with five modules: (1) the conversion of feed nutrients into fish biomass, the “Fish-Biomass-Converter”; (2) the separation of solid and dissolved fish waste/nutrients; the “Fish-Waste-Processor”; (3) the conversion of dissolved fish waste/nutrients, the “Phototrophic-herbivore-Converter”; (4 and 5) the conversion of solid fish waste, the “Bacterial-Waste-Converter”, or the “Detrivorous-Converter”. In the reviewed examples, fish culture alone retains 20–50% feed nitrogen (N) and 15–65% feed phosphorous (P). The combination of fish culture with phototrophic conversion increases nutrient retention of feed N by 15–50% and feed P by up to 53%. If in addition herbivore consumption is included, nutrient retention decreases by 60–85% feed N and 50–90% feed P. This is according to the general observation of nutrient losses from one trophic level to the next. The conversion of nutrients into bacteria and detrivorous worm biomass contributes only in smaller margins (e.g. 7% feed N and 6% feed P and 0.06% feed N 0.03 × 10⁻³% feed P, respectively). All integrated modules have their specific limitations, which are related to uptake kinetics, nutrient preference, unwanted conversion processes and abiotic factors.     

无源无线轮胎压力监测系统研究

轮胎压力监测系统(TPMS)不仅能作为一种预警系统,有效预防轮胎爆胎事故,而且可以降低汽车油耗,保障整车的性能与寿命,能够产生巨大的经济效益和良好的绿色环保作用。首先报告了三种类型的无源TPMS及其优缺点,着重调查了SAW技术(Surface Acoustic Wave)的谐振型和延迟线型TPMS的研究现状,指出了无源无线TPMS实用化有待解决的问题,最后展望了TPMS未来发展的主流趋势。     

平移式喷灌机行走速度及喷灌均匀度试验研究

为研究低压喷灌下喷灌机行走速度合理取值以及喷灌均匀度对土壤含水率均匀度的影响,以自行研制的轻小型平移式喷灌机为研究对象,通过室内单喷头试验和田间喷灌试验,探究了特定灌水定额下喷灌机的工作压力与行走速度关系,并对其水量分布、喷灌均匀度以及土壤含水率均匀度随时间变化进行了分析.结果表明：通过确定灌水定额能够计算出平移式喷灌机的行走速度和工作压力：当灌水定额分别为10,15,20 mm时,40~120 kPa喷灌压力下喷灌机行走速度最小为17.27 m/h,最大为58.65 m/h;增大喷灌压力能小范围提高均匀度,40 kPa工作压力均匀度为0.696,60~120 kPa喷灌压力下均匀度变化范围为0.731~0.788,喷灌水在土壤中的二次分布均匀度明显高于地表喷灌均匀度,40 kPa喷灌压力下喷后6 h土壤含水率均匀度达到0.906,24 h后达到0.953,可相应降低喷灌均匀度设计值以降低运行成本,节约能耗.     

抗菌肽基因异源表达系统研究进展

抗菌肽是机体天然免疫系统的重要组成部分,因具有抗菌谱广、活性稳定、不易产生耐药性等优点而在食品、饲料、农业、医药领域具有重要的应用价值.由于化学合成的成本较高,利用基因工程技术构建高效的生物表达系统成为一个新的途径.综述了抗菌肽在细菌、酵母、植物、动物等表达系统中异源表达的研究进展,为抗菌肽的研究应用提供理论依据.     

A comparison of three land-based containment systems for use in culturing green sea urchins, Strongylocentrotus droebachiensis (Müller) (Echinodermata: Echinoidea)

Worldwide, most sea‐urchin populations are in decline. Future market demands will likely be met through aquaculture, which may consist of gonad enhancement of wild‐caught sea urchins. In this context, we examined three land‐based containment systems for suitability in maintaining commercial‐size green sea urchins (Strongylocentrotus droebachiensis). Mortality rate, gonad quantity, gonad quality (colour, brightness, firmness, texture) and cleaning efficiency associated with each containment system were the criteria for comparing the effectiveness of the systems (large raceways, small raceways and washtub tanks). After 6 weeks, urchins maintained in large raceways displayed significantly higher mortality rates than urchins maintained in either the small raceways or washtub tanks (mean±SD: 24.3±10.4%, 8.0±3.5% and 4.3±1.5% respectively). Significant differences in cleaning time were detected among the three systems with washtub tanks requiring significantly more cleaning time (0.11±0.02 min urchin^?1) than the other two systems and large raceways requiring significantly less cleaning time (0.06±0.02 min urchin^?1) than the other two systems. No significant differences in gonad characteristics were detected among the three containment systems. Because of the higher mortality rate in the large raceways and the increased cleaning time required for the washtub tanks, the small raceways were considered to be the best of the three systems tested.     

用于驱赶农作物有害动物的智能声防系统设计

针对农业生产中动物有害行为导致农作物减产和农产品价值严重损失的实际问题,设计研发出一种驱赶农作物有害动物的智能声防系统。该系统以无线传感器网络作探测和通信平台,采用以ARM9微处理器和AT89C51SND1单片机为核心的嵌入式系统构建总控制器和执行器硬件平台,通过热释电传感器对有害动物在农田中的出没位置进行探测,依据“作物种类–周围环境–有害动物–天敌”逻辑关系模型对其种类作出判断,然后由执行器播放该种动物对应天敌的叫声,从而实现对多种农作物有害动物的智能声防。与现有的驱赶模式易被有害动物适应且效果不佳相比,该系统具有驱赶效果好、有效作用面积大、可扩展性强及装设灵活等优点,是一种无污染、具有智能特性的驱赶农作物有害动物的有效解决方案。