Effects of hydroxy-aluminum on flocculation and permeability of silt and clay fractions separated from paddy soils

Flocculation tests and permeability measurements were carried out for silt and clay fractions separated from surface and subsurface horizons of four paddy soils. There was not much difference in the flocculating power between A1(OH)_2.2C1_0.8 and CaSO₄. Their flocculation value, 0.3 to 3 mM, was attained by adding the reagents at the rate of 0.24 to 2.4 mmol/100 g of the silt and clay. The flocculation with A1(OH)_2.2C1_0.8 or CaSO₄ did not affect the sediment volume of the silt and clay. This sediment volume was smaller for the surface than for the subsurface horizons of each soil, suggesting that soil organic matter and repetition of wetting and drying contribute to the stable aggregation of the silt and clay in the surface horizon. The permeability was higher for the silt and clay fractions separated from the surface horizon than that from the subsurface horizon, and the addition of 2.5 to 4.2 mmol of A1(OH)_2.2C1_0.8 or CaSO₄/100g of the silt and clay increased its permeability by 1.5 to 4 times. The effect of A1(OH)_2.2C1_0.8 was more lasting than that of CaSO₄ and was recognized even after 200 ml of water passed through 1 g of the silt and clay. The effect of the flocculating reagent on the permeability was more or less enhanced by air-drying the treated silt and clay.     

Stability of allophane,allophanic clay,and allophane-halloysite floc in aqueous solutions of an anionic exocellular heteropolysaccharide (Gum Xanthan) from Xanthomonas campestris

Stability of allophane with positive and/or negative charges in the presence of gum xanthan (GX) was mainly investigated at three pH levels. At pH 4.5, allophane showed polymeric iocculation (PFL) at low GX concentrations, and polymeric stabilization (PST) at medium GX concentrations. Flocculated allophane (i.e.p.) at pH 6.5 showed polymeric weak-stabilization (PWST) at extremely low GX concentrations, besides PFL and PST described above. At pH 8.5, allophane did not exhibit any change in stability with GX addition. The PFL and PWST can be regarded as charge neutralization between allophane and GX. Allophanic clay with i.e.p. at pH 10 exhibited both PFL and PST but no PWST, even at pH 8.5. The PWST can be explained by the disintegration of the floc when interparticle attraction was weakened by the adsorption of GX. The lower PWST and PST of allophane-halloysite mutual floc strongly suggested the presence of a more stable arrangement among these dissimilar particles. Stability of crystalline clays was also studied for comparison. The above behavior was analyzed on the basis of (i) the suspended microaggregate of allophane, and (ii) the double-stranded wormlike structure of GX, which was taken in this study as a model substance of anionic microbial polysaccharide.     

壳聚糖对Bt发酵液的絮凝作用

为了将Bt发酵液高效浓缩,采用壳聚糖对Bt菌株LSZ9408发酵液进行絮凝,测定了pH值、温度、壳聚糖浓度、磁力搅拌的速度和时间对壳聚糖絮凝效果的影响。结果显示,当pH值为5.0～6.0,温度30～35℃,壳聚糖浓度为0.025%,磁力搅拌器550r/min搅拌5min后,壳聚糖作为LSZ9408菌株发酵液的絮凝剂,可除去发酵液中的大部分水及有色杂质,使发酵液中的杀虫蛋白质晶体和芽孢得到很好的浓缩。     

硅铁絮凝剂(PFSS)的合成与形态研究

利用活化硅酸和硫酸铁为原料,在不同碱化度和Si／Fe摩尔比条件下,制备出聚合硅酸硫酸铁(PFSS)无机高分子絮凝剂。考察影响产品稳定性的因素,并分析了产品Fe(3),Si(Ⅳ)的形态分布特征,对其可能原因做出微观解释。     

细颗粒泥沙絮凝-分散在水土保持中的应用

简要介绍了细颗粒泥沙絮凝 -分散对土壤渗透性、土壤可蚀性以及污染物迁移的影响 ,以期有效防治水土流失和由此带来的非点源污染。     

三江源地区饮用水源中隐孢子虫和贾地鞭毛虫的检测

通过膜过滤、絮凝沉淀法浓缩收集了三江源地区水源中隐孢子虫和贾第鞭毛虫,并用蔗糖漂浮法纯化了上述"两虫"。及抗酸染色后镜检,结果显示:在三江源地区10条河流中的6条(60%)检出隐孢子虫,32个采样点11个点(34%)的样品检出隐孢子虫;在10条河流中有2条(20%)检出贾地鞭毛虫,32个采样点的4个点(12.5%)的样品中检出贾地鞭毛虫。     

生物絮凝剂的絮凝活性与絮凝条件研究

从活性污泥中筛选出4株具有稳定絮凝活性的菌株,对其中1株进行絮凝活性及絮凝条件的研究。结果表明:其絮凝活性物质主要为菌体分泌物,该菌可产生高絮凝活性的最佳絮凝条件为对于浓度为10 g/L的高岭土,最佳助凝剂为CaCl2,投入量为50 mg/L,pH值为8,絮凝率可达80%以上,具有良好的热稳定性,适于工业化生产。     

臭氧组合絮凝工艺处理牛粪沼液的研究

牛粪沼液作为集约化规模化养殖业阶段处理的产物,产量巨大,有限的土地不足以消纳所有沼液从而导致还田利用十分困难。因此急需寻求一种沼液的预处理方法,实现其固液分离,减少固絮物后续处置量,同时上清液经处理后达标排放。臭氧氧化将大分子有机物降解为小分子物质,絮凝处理可以很好地提高沼液内部固体颗粒的沉降性能,以实现后续上清液的深度处理。该研究采用臭氧+絮凝工艺对牛粪沼液进行预处理,结果表明,单独臭氧处理中,当pH值为7.8,臭氧曝气时间为40 min,臭氧投加速率为2.2 g·h-1时,COD去除率可以达到46%;臭氧+絮凝处理中,当pH值为8.3,搅拌时间为2 min,搅拌速率为300 r·min-1,静置时间为15 min,投药量/总固体TS=1.5,最佳沉降比达到14%,极大地提升了沉降性能,总COD去除率最佳达到82%,最终COD降低到4000 mg·L-1左右,同时为后续处理减轻了负荷,对实际处理有较强的借鉴意义。     

盐酸-壳聚糖絮凝耦合处理回收鲢鱼糜漂洗液中的肌浆蛋白

为提高鱼糜漂洗液中肌浆蛋白的利用率,以鲢鱼糜为研究对象,采用单一壳聚糖絮凝法和盐酸-壳聚糖絮凝耦合处理回收鲢鱼糜漂洗液中的肌浆蛋白,并通过单因素试验和Box-Bechnken中心组合设计对盐酸-壳聚糖絮凝耦合处理的絮凝条件进行优化。结果发现：盐酸处理（pH 3.0）可以显著提高壳聚糖作为单一絮凝剂时的肌浆蛋白回收率（从35.52%提高到81.54%）,肌浆蛋白的最佳回收工艺确定为：pH 6.5,壳聚糖用量250 mg/L,温度30℃,时间90 min。在此条件下,可以获得85.23%的高蛋白质回收率以及73.32%的COD去除率。同时,此方法引入鱼糜漂洗液中的NaCl质量分数为0.006%,不会使后续废水处理成本增加,具有一定的可行性。     

三角褐指藻作为饲料蛋白质的开发前景研究

三角褐指藻是一种单细胞蛋白,蛋白质含量丰富,质量好,动物易消化,并且三角褐指藻容易培养,生长速度快。本文旨在通过测定藻液中的主要营养指标蛋白质的变化,探讨三角褐指藻藻液的采收,研究三角褐指藻作为蛋白质饲料添加到饲料中的可能性,为饲料蛋白质提供新的来源。