Activated sludge denitrification in marine recirculating aquaculture system effluent using external and internal carbon sources

Stringent environmental legislation in Europe, especially in the Baltic Sea area, limits the discharge of nutrients to natural water bodies, limiting the aquaculture production in the region. Therefore, cost-efficient end-of-pipe treatment technologies to reduce nitrogen (N) discharge are required for the sustainable growth of marine land-based RAS. The following study examined the potential of fed batch reactors (FBR) in treating saline RAS effluents, aiming to define optimal operational conditions and evaluate the activated sludge denitrification capacity using external (acetate, propionate and ethanol) and internal carbon sources (RAS fish organic waste (FOW) and RAS fermented fish organic waste (FFOW)). The results show that between the evaluated operation cycle times (2, 4, and 6 h), the highest nitrate/nitrite removal rate was achieved at an operation cycle time of 2 h (corresponding to a hydraulic retention time of 2.5 h) when acetate was used as a carbon source. The specific denitrification rates were 98.7 ± 3.4 mg NO₃⁻-N/(h g biomass) and 93.2 ± 13.6 mg NO_x⁻-N/(h g biomass), with a resulting volumetric denitrification capacity of 1.20 kg NO₃⁻-N/(m³ reactor d). The usage of external and internal carbon sources at an operation cycle time of 4 h demonstrated that acetate had the highest nitrate removal rate (57.6 ± 6.6 mg N/(h g biomass)), followed by propionate (37.5 ± 6.3 mg NO₃⁻-N/(h g biomass)), ethanol (25.5 ± 6.0 mg NO₃⁻-N/(h g biomass)) and internal carbon sources (7.7 ± 1.6–14.1 ± 2.2 mg NO₃⁻-N/(h g biomass)). No TAN (Total Ammonia Nitrogen) or PO₄^3- accumulation was observed in the effluent when using the external carbon sources, while 0.9 ± 0.5 mg TAN/L and 3.9 ± 1.5 mg PO₄^3--P/L was found in the effluent when using the FOW, and 8.1±0.7 mg TAN/L and 7.3 ± 0.9 mg PO₄^3--P/L when using FFOW. Average sulfide concentrations varied between 0.002 and 0.008 mg S^2-/L when using the acetate, propionate and FOW, while using ethanol resulted in the accumulation of sulfide (0.26 ± 0.17 mg S^2-/L). Altogether, it was demonstrated that FBR has a great potential for end-of-pipe denitrification in marine land-based RAS, with a reliable operation and a reduced reactor volume as compared to the other available technologies. Using acetate, the required reactor volume is less than half of what is needed for other evaluated carbon sources, due to the higher denitrification rate achieved. Additionally, combined use of both internal and external carbon sources would further reduce the operational carbon cost.     

Upregulation of the PI3K/Akt Pathway in the Tumorigenesis of Canine Thyroid Carcinoma

Background

Information on the genetic events leading to thyroid cancer in dogs is lacking.

Hypothesis/Objectives

Upregulation of the PI3K/Akt pathway has an important role in the tumorigenesis of thyroid carcinoma in dogs.

Animals

Fifty‐nine dogs with thyroid carcinoma and 10 healthy controls.

Methods

Quantitative RT‐PCR was performed for VEGFR‐1, VEGFR‐2, EGFR, PIK3CA, PIK3CB, PDPK1, PTEN, AKT1, AKT2, COX‐2, and CALCA. Mutation analysis was performed for known hotspots of RAS (N, K, H), PIK3CA, BRAF, RET, and for the entire coding region of PTEN.

Results

Forty‐three dogs (73%) had follicular cell thyroid carcinoma (FTC) and 16 dogs (27%) had medullary thyroid carcinoma (MTC). The relative mRNA expressions of VEGFR‐1 (P < .001), VEGFR‐2 (P = .002), PDPK1 (P < .001), AKT1 (P = .009), and AKT2 (P < .001) were increased in FTC, and those of EGFR (P < .001), VEGFR‐1 (P = .036), and PIK3CA (P = .019) were increased in MTC when compared to normal thyroid glands. Mutation analysis of K‐RAS identified 2 activating missense mutations, which also have been described in thyroid cancer of humans. A G12R substitution was present in 1 FTC and an E63K substitution was present in 1 MTC. No functional mutations were found in the sequenced regions of H‐RAS, N‐RAS, PIK3CA, BRAF, RET, and PTEN.

Conclusions and Clinical Importance

The increased expression of several genes associated with PI3K/Akt signaling suggests the involvement of this pathway in the pathogenesis of thyroid carcinoma in dogs, warranting further research on pathway activation and gene amplification. The mutations most frequently associated with thyroid cancer in humans are rare in dogs.     

The ratio between digestible protein and digestible energy affects accumulation and depuration of geosmin and 2-methylisoborneol (2-MIB) in Japanese seabass (Lateolabrax japonicus) raised in a recirculated aquaculture system

Actinobacteria and cyanobacteria accounted for less than 1% of total of bacteria in water in a recirculated aquaculture system (RAS) during a 15-week feeding trial with 0.11-g Japanese seabass. Resulting concentration of geosmin and 2-methylisoborneol (2-MIB) in RAS water was 169 and 45 ng L^?1, sufficient to produce strong off-flavour. The seabass were fed diets with 42%, 45% and 49% protein, and each protein level was supplemented with 15% or 18% lipid. Accumulation of off-flavours was independent of diet in fatty ventral tissue. Dietary protein significantly reduced off-flavours in lean, dorsal tissue. This was mainly rationalized by linear reduction in 2-MIB in response to increasing DP/DE and a strong, 2nd degree polynomial response in geosmin. The ratio between geosmin and 2-MIB was slightly higher at the beginning of a 10-day period with clean water and fasting, than what was observed throughout depuration. 2-MIB remained between 0.2 and 1 µg kg^?1 in dorsal tissue throughout depuration. Geosmin in ventral tissue ranged from 10 to more than 30 µg kg^?1at the termination of the feeding period and was reduced to a range from 6 to 20 µg kg^?1 by depuration.     

基于证书认证机制的公平文件交换协议的算法设计

在电子商务活动中，进行实时公平的文件交换具有非常重要的意义．本文利用证书认证机制中简单、快速且交换活动脱离等特点，结合RSA算法构造出具备实时公平交换功能的文件交换协议．同时根据测试数据对该协议的各项性能与其它类似协议进行了简要分析．最后提出了可行的协议假定的实现流程．     

脂肪和蛋白质营养对工业化养殖大西洋鲑相关代谢酶和生长基因表达的影响

为探究主要脂肪和蛋白质水平对工业化养殖大西洋鲑(Salmo salar)成鱼脂肪相关代谢酶和生长相关基因表达的影响,本实验采用3×2双因素随机实验设计,设置3个脂肪水平:18%、21%、24%(分别以F18、F21、F24表示),2个蛋白质水平:38%、48%(分别以P38、P48表示)。组合为6个实验处理组,每组3个重复,每重复40尾鱼。实验在室内封闭循环水养殖系统中进行,实验鱼初始体重(650.0±45.50)g,实验期56 d。结果表明:(1)工业化养殖实验鱼的脂肪需求较国外深海网箱养殖明显降低,蛋白质需求相近。P48F21组增重率显著最佳,较其他各组提高22.23%~125.86%(P0.05);P48F24组饲料系数显著最低,较其他各组降低16.24%~30.00%(P0.05)。(2)单因素高脂肪显著提高肝体比(P0.05),高蛋白极显著降低肥满度(P0.01);P48F24组肝体比较其他各组显著提高10.92%~28.16%(P0.05),P48F18组肥满度较其他各组显著降低10.24%~12.31%(P0.05);并创新提出了600~900 g大西洋鲑形体营养调控初步方案。(3)单因素高、中脂肪显著提高肝脂肪分解酶(HL、LPL和总酯酶)活力,高蛋白显著提高LPL和总酯酶活力;P48F21和P48F24组饲粮显著提高肝脂肪分解酶活力,其中LPL活力比P38F18组分别提高46.51%、48.84%(P0.05)。实验处理主要对肝脂肪分解酶产生作用,显现了两组优良饲粮改善生长性能的脂肪生理代谢机制。(4)单因素中脂肪极显著增加肌肉和肝IGF-I基因表达量(P0.01);高蛋白极显著增加肌肉GH、IGF-I及肝IGF-I基因表达量(P0.01);GHR基因表达量,随脂肪或蛋白水平升高均有显著下降特征(P0.05)。P48F21和P48F24组试鱼肌肉GH、IGF-I及肝IGF-I基因表达量显著提高(P0.05),肌肉和肝GHR基因表达量显著降低(P0.05)。初步的新发现是,GH和IGF-I与GHR存在相互制约的负相关内在调控关系,以自身控制鱼类生长和生殖活动处于相对稳定和可控状态下。本研究初步确定,P48F21和P48F24组是工业化养殖大西洋鲑成鱼的主要营养素优良组合饲粮,其中以显著降低脂肪水平和饲料成本的P48F21组合饲粮更佳。     

七带石斑鱼和云纹石斑鱼幼鱼在封闭循环水条件下的生长特性

观测研究了七带石斑鱼(Epinephelus septemfasciatus)幼鱼和云纹石斑鱼(Epinephelus moara)幼鱼在封闭式循环养殖系统中的生长特性,用SPSS 17.0软件中的Curve Estimation对相关数据进行模型分析与参数估计。结果表明,经过122 d的养殖,七带石斑鱼幼鱼平均体质量由(114.836±25.343)g增加到(213.861±38.604)g,相对增长率为0.707%,全长(TL)与养殖时间(t)的函数关系式为TL=-0.006t3+1.622t+13.954,体质量(W)与体长(BL)的关系式为W=0.436BL2.055;云纹石斑鱼幼鱼平均体质量由(79.620±13.007)g增加到(238.086±46.307)g,相对增长率为1.631%,全长(TL)与养殖时间(t)的函数关系式为TL=-0.013t2+2.008t+11.540,体质量(W)与体长(BL)的关系式为W=0.018BL3.083。两种幼鱼丰满度生长差异不显著(P0.05),都保持在2.2-3.4之间。     

基于循环水养殖系统的罗非鱼养殖效果分析

为掌握罗非鱼在循环水养殖系统的高密度养殖生产过程中的水质变化情况及生长数据等,以吉富罗非鱼为养殖对象,构建一套集成有竖流沉淀器、转鼓式微滤机、生物移动床、多腔喷淋式纯氧混合器、滴流式脱气滤塔及消毒杀菌装置等高效水处理技术和装备的高密度系统,并使用该系统进行为期3个月的吉富罗非鱼养殖试验。试验研究结果显示:罗非鱼在高密度养殖条件下摄食和生长情况正常,养殖密度从投入时的3.5 kg/m3快速增长至32 kg/m3,饵料系数1.72;循环系统水处理环节水质调控能力显著,处理后的养殖水体水质参数稳定:日换水量维持在5%左右的情况下,温度保持在23~28.0℃,氨氮浓度维持在0.272 mg/L,亚硝酸盐维持在0.067~0.21 mg/L,COD平均为7.15 mg/L,溶解氧浓度平均值为7.40 mg/L。总之,将循环水养殖系统应用在罗非鱼养殖中,是一种可行且高效的方法。     

生物膜法SBR（BSBR）在循环养殖水处理中影响因素分析

膜法SBR（sequence batch reactor）是将SBR法与接触氧化法相结合的一种新型生物膜法处理工艺。此研究以总氨氮（TAN）及总氮（TN）的去除反应速度作为考察指标,分析生物膜法SBR（biofilm sequence batch reactor,BSBR）处理水产循环养殖系统水体中影响TAN及TN去除效果的主要因素。其中,pH和碱度对硝化反应有很大的影响,pH控制在6．3以上时TAN处理效果较好。溶解氧（DO）对反硝化反应也有较大的影响,同时考虑到水生生物的生长需求,在此试验系统中进入反应器的水体DO最好能控制在4．5～6．5mg·L^-1。水温保持在20％左右,可以保证有一个较好的脱氮效果。     

半滑舌鳎的循环水养殖模式及经济效益分析

2009年3月至10月进行了半滑舌鳎(Cynoglossuss semilaevis Guanther)生产性养殖试验,期间对一套循环水养殖系统的水处理效果及半滑舌鳎养殖模式进行了深入的研究。养殖水体经系统处理后,养殖池内水温18～21℃,pH 7.0～8.0,DO≥6.6 mg/L,养殖池进水氨氮0.017～0.178 mg/L,亚硝酸氮0.012～0.064mg/L。文中详细阐述了放苗前养殖车间消毒、苗种选择与运输、生物滤池的培养、苗种投放、养殖过程中系统的日常维护、饵料投喂、光照控制、水质因子控制等内容,并对养殖半滑舌鳎8个月的经济效益进行了分析。以期为国内工厂化循环水养殖半滑舌鳎提供技术支持和经济效益分析方面的参考。     

Influence of feeding sequence,light and colour on the performance of a self-grading system designed for turbot (Scophthalmus maximus)

Grading of cultured flatfish is essential to maintain even sizes and to avoid potential feeding dominance or cannibalism. Current hand-grading and forced mechanical grading methods result in labour costs and additional stress to animals, reducing their growth performance. This study tested a self-grading system allowing turbot (Scophthalmus maximus) to self-grade, based on size, between tank sections within 8000 L tanks designated as “Graded (G)” and “Non-Graded (NG)”. The grading success (percentage of graded animals/total gradable individuals) with stimuli (light, feeding sequence and colour of the grading device) and without stimuli was analyzed over 9 days. Mean grading success without stimuli was 38.1 ± 11.5%. Grading success was not improved by changes in feeding sequence (30.6 ± 10.2%) or altered colour of the grading device (30.9 ± 13.8%). Marked increases in grading success were obtained by adding a light source to the G section (52.9 ± 12.4%), and by combining the presence of a light source and the feeding sequence (57.9 ± 14.4%). The combination of light sources and changes to the colour of the self-grading device resulted in the highest mean grading success (72.1 ± 18.2%) overall. Light and colour stimuli combined yielded the highest self-grading maximum (88.36 ± 5.3%), achieved on day 6 after experimental onset. A three-parameter asymptotic exponential equation was fitted to the data from each stimulus and parameters describing the curves of all conditions are reported. The present results indicate that the tested self-grading systems for turbot can be highly efficient if used with the appropriate stimuli. Self-grading systems operating at the measured levels of success offer a viable alternative to stressful grading events, avoiding significant commercial disadvantages as well as improving animal welfare and performance.