Reducing bacterial density in the semen of rainbow trout (Oncorhynchus mykiss) by applying gradient centrifugation and swim‐up washing methods

The objective of this study was to demonstrate the effectiveness of disinfection procedures to reduce bacterial load of rainbow trout, Oncorhynchus mykiss (Walbaum 1792), semen. Fresh semen was obtained from 3–4‐year‐old male species by abdominal sampling of sperm into pre‐cooled test tubes. After sperm cryopreservation and thawing, experiments were accomplished at 4–9°C. ‘Swim‐up’ and gradient centrifugation were used as a sperm washing method with commercial kits. Phosphate buffered saline was also used as washing solution. Bacterial growth tests were employed before and after washing the semen samples. Samples were inoculated on tryptic soy agar (TSA), modified Anacker and Ordal agar (MAOA) as well as brain heart infusion (BHI) agar. After using ‘swim‐up’ method for washing the semen, many bacterial colonies were observed. However, after semen washing with gradient centrifugation, lower bacterial growth was observed on TSA, MAOA and BHI. Some motile (40%) spermatozoa were obtained doing gradient washing procedure. Although sperm motility was not satisfactory, apparently the gradient centrifugation method reduced bacterial contamination as known from the mammalians.     

Polysaccharides as Coagulants for the Recovery of Protein in Fish Meal Wastewater

ABSTRACT

In this study, polysaccharides were applied to recover protein from fish meal wastewater. The coagulation performance was optimized, and the protein recovery rates for carrageenan, guar, chitosan, and alginate were found to be 70, 49, 53, and 55%, respectively. The floc formation, including its dynamic and morphology, were investigated using small angle static light scattering. Through comparison, carrageenan is the best natural coagulant. Although its floc growth rate was the slowest (1.61 µm/s) among those tested, it exhibited the highest recovery rate (70%) and the most compact floc structure with the fractal dimension of 2.31.     

Characterization of Sardine Minced Flesh (Sardinella aurita) Washed with Different Solutions

Abstract

Minced sardine was washed with sodium bicarbonate (0.5%) and water to evaluate their effectiveness in removing components such as protein, fat, ash and non-protein nitrogen. Mince washed with NaHCO₃ showed greater reductions in protein and nitrogen compounds and had a lighter color, while water washed mince showed highest reductions in ash and lipid components. Moisture and pH increased with the number of washing exchanges. Centrifugation after each washing cycle did significantly reduce the components compared to a one step centrifugation dewatering process.     

柠檬酸对铬污染不同质地土壤萃取与淋洗的研究

为了探索柠檬酸对不同质地铬（Cr）污染土壤的萃取条件及淋洗效率,进行了不同浓度、固液比、时间的萃取和土柱淋洗试验。结果表明：柠檬酸对铬污染不同质地土壤修复效果为：砂土＞壤土＞粘土;砂土、壤土所需萃取条件较小,粘土较大。不同萃取条件对铬污染土壤萃取效果影响较大：柠檬酸浓度为0.05 mol/L时,3种土壤萃取效果较好。3种质地土壤最佳固液比和时间分别为：粘土1/14,32 h;砂土1/6,16 h;壤土1/10,28 h。通过柠檬酸淋洗,粘土在10~20 cm土层发生再吸附,砂土与壤土在30~40 cm土层发生再吸附。本研究为铬污染土壤修复了提供技术支持。     

养殖废水中抗生素与重金属交叉抗性微生物的筛选及其抗性研究

为了探索废水中具有抗生素和重金属交叉抗性的微生物的抗性机制以及抗性微生物的种类,直接从含养殖场废水的选择培养基中分离菌种,通过设计试验,观察其在含有重金属(Pb2+：33.33 mg/L,Cr6+：34.67 mg/L,Hg2+：16.67 mg/L,Cu2+：33.33 mg/L)和抗生素（阿莫西林A：3.33 mg/L,诺佛沙星N：2.67 mg/L,头孢拉定C：4.17 mg/L）的二元交叉培养基上的生长情况。结果表明：分离得到的7株菌中,4株为G-杆菌,3株为G+杆菌。所有二元交叉培养基上均有抗性菌生长,G-菌的抗性明显强于G+菌,其中1#菌具有六重交叉抗性(Pb+A、Cr+N、Hg+N、Hg+C、Cu+A、Cu+C),4#和7#菌均只具有一重交叉抗性,分别为Cu+N和Cr+C,具有Hg+N交叉抗性的菌最多,有4株,而具有Cr+N、Pb+C、Cu+C或Cr+C交叉抗性的菌均只有1株,菌种对抗生素的抗性强于对重金属的抗性。因此,养殖废水排放可能引发抗生素和重金属交叉抗性微生物的公众健康危害。     

薯类淀粉废水处理技术及资源化利用研究进展

薯类淀粉加工过程中产生的大量高浓度有机废水不仅严重污染环境,还造成了资源的巨大浪费。对薯类淀粉废水处理及其资源化利用方法进行了综述,介绍了絮凝沉淀法、生物处理法及土地处理法在薯类淀粉废水处理方面的发展和运用,及薯类淀粉废水处理资源化利用的途径。指出回收、利用废水中的有效成分不仅具有一定的经济效益,而且可有效降低废水污染负荷,减轻后续处理的压力。参48     

Dyeing properties and colour fastness of wool dyed with indicaxanthin natural dye

This research work involves the dyeing of wool with indicaxanthin, a natural dye extracted from fruits of Opuntia ficus-indica. The optimal conditions for dye extraction were to mix 50 g of Juice from cactus pears with 100 mL of 80% aqueous ethanol as solvent for dye extraction. Liquid chromatography was applied for the separation. Two main dyes were obtained, which were identified as indicaxanthin (75 mg per 50 g) and betanin (5 mg per 50 g). The effect of dye bath pH, salt concentration, dyeing time and temperature were studied. The optimal conditions for wool dyeing with indicaxanthin dye were carried out at 70 °C for 90 min with the pre-treatment of various metal salts as mordant. The colour yields of the dye on the wool were found to be highly dependent of the pH, optimum results being obtained at pH 4. The K/S of wool increased in the order of the dyeing using KAl (SO₄)₂ > MnSO₄ > CoSO₄ > FeSO₄ > none > ZnSO₄ > CuSO₄. Un-mordanted samples have good properties of water and washing fastness. Mordants KAl (SO₄)₂ and CoSO₄ were found to give good light fastness (rating 5).     

农村沼气使用现状及其对生活污水治理的意义——以河北省、山东省农村为例

我国农村每年都会产生大量的生活污水,这些污水几乎没有经过处理就排放到环境中,不仅给流域水环境造成巨大压力,而且给人类健康带来严重威胁.沼气技术可以将人畜粪便中的主要污染物转化为沼气燃料及有机肥,对农村生活污水的治理具有重要意义.尽管当前全国各地不断加大农村沼气的建设力度,但是调查发现其实际使用情况不容乐观,并且与农村污水治理尚未很好的结合.笔者通过对河北、山东部分农村地区沼气池的使用情况进行调研,进一步探索农村沼气建设和管理模式,使其效益能得到长期稳定发挥.     

稀土氨氮废水对黄河包头段水质的影响

在分析稀土生产工艺、稀土氨氮废水产生及废水水质具体情况的基础上,详细分析黄河包头段氨氮污染状况,结果表明造成黄河包头段水质下降的原因与稀土废水中氨氮超标排放有直接关系。另外,黄河氨氮浓度在枯水期达不到功能区水质目标,说明污染主要来自工业和城镇生活的点污染源。     

冷冻白姑鱼糜凝胶特性改良生产工艺研究

以舟山产的冷冻小规格白姑鱼为对象,以漂洗过程CCP1和凝胶增强剂的使用CCP2作为2个关键控制点,分别采用单因素和正交实验法对白姑鱼鱼糜生产新工艺进行了研究。结果表明：最佳的工艺条件是CCP1漂洗工艺中为漂洗水1.0 mg/mL柠檬酸钠溶液,漂洗温度8℃,漂洗时间12 min;CCP2凝胶增强剂使用上,工艺选择用2%鸡蛋白添加量,3%马铃薯淀粉与0.2%GRA1作为复合凝胶增强剂。在该工艺条件下,白姑鱼鱼糜凝胶强度为855.43 g.cm,是传统工艺的4倍以上。