Effects of Co-Existing Ions on the Phosphorus Potassium Ratio of the Precipitate Formed in the Potassium Phosphate Crystallization Process

Livestock wastewater is mainly treated with activated sludge, but ions such as phosphorus, potassium, ammonium, nitrate and sulfate remain in the effluent. In this study, the effects of residual ions on phosphorus recovery using the magnesium potassium phosphate crystallization method were investigated when magnesium was added to increase the pH. If co-existing ions affect the products, the phosphorus to potassium molar ratio (K/P ratio) of the precipitate will deviate from being equimolar. Artificial wastewater test solutions containing 5.6 - 20.3 mM ammonium, 25.6 mM potassium, 6.5 mM phosphorus, 0 - 7.35 mM nitrate, and 0 - 3.06 mM sulfate were used. First, the optimum operating pH and amount of magnesium added to give a high phosphorus removal rate and recovery rate were determined. The experimental setup was a 10 L aerated and stirred reactor, and a 5 L settling tank. The K/P ratio in precipitate was approximately 1 using the optimum conditions. Continuous 2 h treatment allowed a white precipitate containing about 30 g of needle-like crystals to be obtained. Next, the effects of varying the ammonium, nitrate, and sulfate ion concentrations in the artificial effluent were investigated. Ammonium and sulfate ion concentrations of 8 mM or more and 3 mM or more, respectively, caused the K/P ratio to decrease to about 0.7 and 0.5, respectively. Varying the nitrate concentration did not affect the K/P ratio, even at a nitrate concentration of 7.35 mM.

Influence of pH on Formation of Taranakites

Monoammonium phosphate (1 mol L-1), monopotassium phosphate (1 mol L-1) and aluminum ohloride (5×10-3 mol L-1) were used to investigate the influence of pH on the formation of NH4-taranakite and K-taranakite in systems with a high NH4H2PO4 or KH2PO4 concentration. The experimental data indicated that the reaction products of aluminum with NH4H2PO4 or KH2PO4 changed with the pH in the systems. In a pH range of 2.5 to 10.0, as the pH increased, the products in either ammonium or potassium system followed the sequence: taranakite, amorphous (NH4, K)2AlH(PO4)2 .4H2O, and then crystalline (NH4, K)AlPO4OH.2H2O. However, the pH ranges of the formation of these products in ammonium system were different from potassium system. NH4-taranakite formed from pH 2.75 to PH 5.75, whereas K-taranakite formed in the pH range of 3.00 to 5.00. From the theoretical calculation by a computer program (GEOCHEM version 2.0), NH4-taranakite and K-taranakite could form at the pH from 1.50 to 8.30 and from 1.25 to 8.45,respectively. These pH ranges were much wider than the experimental results. The difference between the experimental data and theoretical data was attributed to the lack of kinetic data and/or the incompleteness and inaccuracy of the thermodynamic data in the data base of the program. The PH ranges of the formation of the taranakites indicated that the taranakites could exist in the immediate vicinity of phosphate fertilizer zone as reaction products of phosphate fertilizers with soils, especially acidic soils, resulting in the fixation of not only phosphate but also nitrogen and/or potassium in soils.

叶面喷施磷酸二氢钾铵对猕猴桃果实发育和品质的影响研究

为促进猕猴桃果实发育,提高果实品质,以中华绿肉猕猴桃为试验品种,叶面喷施0.5%磷酸二氢钾铵,研究喷施叶面肥磷酸二氢钾铵对猕猴桃果实发育和品质的影响。结果表明,喷施叶面肥磷酸二氢钾铵可促进果实果梗长度、粗度以及果实横径、纵径的发育;显著提高猕猴桃果实中维生素C含量,但对猕猴桃果实重量、可溶性固形物含量及可滴定酸含量无显著影响。

长期施肥下毛竹林土壤的肥力质量研究

2014-2015年,在浙江省16个县（区/市）的毛竹（Phyllostachys heterocycla cv.pubescens）林地共采集1 141份土壤样品,分析p H值、有机质、速效钾、有效磷和铵态氮,并采用层次分析法,对其肥力质量进行综合评价。结果表明,浙江省毛竹林地土壤肥力质量总体上较好,占68.75%,其中常山和德清的土壤肥力质量最优,土壤肥力质量指数分别为1.013 5和1.093 6;土壤肥力质量处于中等及以下水平的占31.25%,龙泉、绍兴、龙游的土壤质量较差。相关分析显示,土壤的铵态氮与计算得到的土壤肥力质量综合指数呈现极显著的相关性（R=0.943,P〈0.01）,另外,土壤有机质和速效钾含量与土壤肥力质量综合指数也呈极显著的正相关,其相关系数平方值分别达到了0.640（P〈0.01）和0.670（P〈0.01）,表明氮元素、有机质和速效钾含量是衡量土壤肥力质量的重要指标。毛竹林地土壤p H在4.5~8.5,平均为4.84,土壤的酸化与林农偏施氮肥有一定的关系。

磷酸二氢钾铵对水稻的营养效应研究

采用裂区设计 ,田间生物试验的方法 ,研究了磷酸二氢钾铵不同用量及不同施用方法在中性紫色土上对水稻的营养效应。结果表明 ,化成复肥供量较低时 ,产量随供肥量的增加而增加 ,复肥供量处理为 6 0 0kg/hm2 时 ,获得最高产量 ,主区为 7711kg/hm2 ,副区为 714 4kg/hm2 ,比CK分别增产 33.73%和 2 3.4 3% ,过量供应 ,养分累积量增加极缓 ,趋于稳定 ,单位养分的增产量及肥料利用率则显著降低 ,产量甚至出现下滑。相同供肥量不同施用方法比较 ,分次施肥比 1次基施 ,水稻对化成复肥中氮素和磷素利用率提高分别为 31.4 3%～ 34.88%和 30 .39%～ 32 .2 0 % ,而对钾素累积量和利用率影响较小 ,分次施肥较 1次基施增产幅度为 6 .95 %～ 7.94 %。品质分析表明 ,水稻籽粒蛋白质含量随复肥供量的增加而增加 ,分次施肥和 1次基施增加幅度分别达 16 .81%～ 19.5 2 %和 17.6 9%～ 19.34% ,但对淀粉含量影响相对较小 ,淀粉含量有随蛋白质含量增加而略有下降的趋势。适量供肥及合理施用方法可增加水稻叶片叶绿素含量、提高同化效率、增加水稻穗长、穗粒数等 。

以氯化铵为基的颗粒复混肥性能研究

本文讨论了以氯化铵为基的颗粒复混肥的造粒及产品特性，测定了颗粒的抗压碎强度、水份影响及Ｐ２Ｏ５的退化率等参数，确定了产品的稳定性。

新型控制释放肥料 Luxecote 结构的实验研究

介绍了１种以二价金属磷酸铵钾盐包裹水溶性氮肥的新型控制释放肥料，其商品名称为Ｌｕｘｅｃｏｔｅ。通过扫描电镜观察包裹层结构；Ｘ—射线衍射分析鉴别包裹层的构成；以及利用快速比表面分析仪测定包裹层的微孔径结构及孔分布，从而了解这种新型控制释放肥料的养分释放特性。

钾、镁配施改良茶园土壤酸化的效果及其作用路径

为明确改良茶园土壤酸化的适宜钾、镁肥配施量及其对土壤pH的作用路径,在酸化茶园土壤(pH 3.43)设置4个钾肥和镁肥不同浓度交叉的16个处理,恒温恒湿培养5、10、20、30、45、60 d。结果表明:不同浓度钾、镁肥配施均能提高土壤pH,当K^(+)为27.5 mg·kg^(-1)、Mg^(2+)为240 mg·kg^(-1)(低钾高镁)时,pH提高了0.61个单位(P<0.05),改良茶园土壤酸化的效果最佳;在该处理下,交换性酸、NO_(3)^(-)-N含量显著降低,交换性K^(+)、Mg^(2+)、Na^(+)、NH_(4)^(+)-N含量显著增加;结构方程模型分析发现,交换性Mg^(2+)、Na^(+)对pH有显著正向直接效应,交换性Al^(3+)对pH有极显著负向直接效应(P<0.01),交换性Mg^(2+)和NH_(4)^(+)-N对pH有极显著正向间接效应。因此,低钾高镁改良茶园土壤酸化的主要作用路径是增加交换性Mg^(2+)、交换性Na^(+)和NH_(4)^(+)-N含量,降低交换性Al^(3+)含量。