Effect of humic substances on the precipitation of calcium phosphate

For phosphorus （P） recovery from wastewater, the effect of humic substances （HS） on the precipitation of calcium phosphate was studied. Batch experiments of calcium phosphate precipitation were undertaken with synthetic water that contained 20 mg/L phosphate （as P） and 20 mg/L HS （as dissolved organic carbon, DOC） at a constant pH value in the range of 8.0-10.0. The concentration variations of phosphate, calcium （Ca） and HS were measured in the precipitation process; the crystalline state and compositions of the precipitates were analysed by powder X-ray diffraction （XRD） and chemical methods, respectively. It showed that at solution pH 8.0, the precipitation rate and removal efficiency of phosphate were greatly reduced by HS, but at solution pH ≥9.0, the effect of HS was very small. The Ca consumption for the precipitation of phosphate increased when HS was added; HS was also removed from solution with the precipitation of calcium phosphate. At solution pH 8.0 and HS concentrations ≤3.5 mg/L, and at pH ≥ 9.0 and HS concentrations ≤ 10 mg/L, the final precipitates were proved to be hydroxyapatite （HAP） by XRD. The increases of solution pH value and initial Ca/P ratio helped reduce the influence of HS on the precipitation of phosphate.     

反硝化颗粒污泥在纳米零价铁胁迫下的性能恢复

为探明纳米零价铁(nZVI)对反硝化颗粒污泥(DGS)潜在的胁迫效应,本研究通过连续多批次实验,考察了经历n ZVI短期冲击后,DGS反硝化活性在不同C/N比条件下的恢复情况.结果表明,当nZVI投加量高于5 mg·L~(-1)时,DGS比反硝化速率(μ)会出现下降,对应的比反硝化抑制率(IR)与基质C/N比、nZVI投加量呈现正相关.当nZVI投加量达到100 mg·L~(-1)时,胞外蛋白与多糖含量均明显降低.此时,充足的外加碳源(C/N≥4)将有助于促进DGS反硝化活性的恢复和减少去除单位硝态氮所消耗的COD值.由Freundlich和Langmuir吸附等温线的拟合结果可知,基质C/N比越高,DGS对n ZVI的吸附能力就越强.在恢复期内,泥相中总铁含量(Qe)的持续削减为高C/N比条件下,DGS反硝化活性的提升创造了有利条件.当Qe降至0.4 mg·g~(-1)以下时,μ值可达到或接近对照组的水平.     

摩尔配比对MAP沉淀法回收模拟废水中磷的影响

以磷浓度50mg/L的实验室模拟废水为研究对象,考察了以鸟粪石(MAP)形式回收磷的最佳摩尔配比,并借助X-衍射(XRD)对不同摩尔配比条件下得到的沉淀物进行分析。试验结果表明,在pH=9.5时,以鸟粪石形式回收磷的最佳Mg:N:P=4:1.6:1。对沉淀物的XRD分析发现,在pH=9.5,当固定Mg:P=1.6时,N:P=1时沉淀物中基本不含MAP,当N:P=2时,生成的沉淀物中混有少量的副产物Mg(3PO)42,当N:P2时则生成较纯的MAP;当固定N:P=4时,Mg:P=2是生成较纯的MAP的临界值,超过此比例则生成副产物Mg(3PO)42;当反应按照理论配比投加氨氮和镁盐时,所得产物基本不是MAP,而是副产物Mg(3PO)42。故鸟粪石沉淀结晶反应中应尽量提高氨氮配比,并避免投加过量的镁盐,以保证回收产物的纯度。     

城市污泥中磷的释放与回收

基于我国磷资源和城市污泥的现状,针对城市污泥中的营养元素,分析了城市污泥中磷回收的必要性;探讨了城市污泥中磷由固相释放至液相的微生物消化法、热处理法和药剂溶出法等;综述了回收液相中磷的磷酸铵镁、磷酸镁钾、磷酸钠钾镁结晶法和磷酸钙盐沉淀法的原理和研究现状;展望了城市污泥中磷释放与回收技术的研究、开发与应用前景。     

萃取-反萃法综合回收磷矿浮选尾矿中磷和镁

针对某磷矿浮选尾矿的资源特点,将其作为高镁低品位磷矿进行处理,用萃取-反萃法分离酸浸液中的镁和磷。选择正丁醇作为萃取剂,在磷酸浓度为30%、萃取相比为1:1,温度为常温,萃取时间为5min的均衡搅拌条件下,五氧化二磷萃取率可达68%以上;用水作为反萃剂,在其加入量为反萃前有机相体积的30%,反萃时间为3min,常温条件下进行反萃,反萃率可达90%以上。该研究为综合回收磷矿浮选尾矿提供了基础性资料,     

上海市电子废弃物产生量预测与回收网络建立

以上海市为例,利用无容量限制的设施选址模型(UFCLP模型)建立了上海市电子废弃物(WEEE)回收网络,同时,为获得模型求解所需数据,根据1991～2012年的销售量对上海市2010～2017年彩电、冰箱、洗衣机、空调和电脑的废弃量进行了预测.结果表明,5种电子产品的总废弃量会从2010年的269.49×104台增至2017年的635.75×104台.最后,依据区域GDP、人口密度和区域面积等多因素对电子废弃物空间分布量进行了预测,并以此为基础选取了214个回收站候选点,使用SITATION软件对UFCLP模型进行求解,最终确定10个点作为拟建回收点,可实现未来上海市约76%的电子废弃物回收.该网络的建立对长三角地区和全国大中型城市电子废弃物回收都具有良好的示范作用.     

Residual dynamics of thiacloprid in medical herbs marjoram, thyme, and camomile and in soil

Thiacloprid is a new insecticide of the chloronicotinyl family. To assess its risk after application, residual characteristics of thiacloprid in marjoram, thyme, and camomile and in soil were studied under field conditions. The active ingredient was extracted from the plant material using a mixture of acetone-water. After filtration, the extract was concentrated to the aqueous phase, diluted with water, and portioned against ethyl acetate on a matrix solid phase dispersion column. Thiacloprid was extracted from soil using a mixture of methanol-water, filtered, and re.extracted （clean up） with dichloromethane. The residues were quantified using HPLC-MS-MS. The methods were validated by recovery experiments. Thiacloprid residues in marjoram, thyme, and camomile and in soil persisted beyond 10, 14, 14, and 21 d but no residues were detected after 14, 21, 21, and 28 d, respectively. The data obtained in this study indicated that the biexponential model is more suitable than the first-order function to describe the decline of thiacloprid in fresh marjoram, fresh thyme, and dried camomile flowers with half-life （t1/2） of 1.1, 0.7, and 1.2 d, respectively. However, both the first-order function and biexponential model were found to be applicable for dissipation of thiacloprid in soil with almost the same t1/2 values of 3.5 and 3.6 d. The results indicated that thiacloprid dissipates rapidly and does not accumulate in the tested herbs and in soil.     

从废水中回收沼气能及氢能与电能

厌氧发酵制沼气、厌氧发酵制氢和微生物燃料电池技术是利用微生物在废水处理的同时回收能源的三种主要方式。文章结合相关研究现状,介绍了这三种技术的基本原理及其在废水处理领域的发展状况和展望,并对三种生物能源进行了比较。     

吸收液对中空纤维膜接触器回收尿液中氨氮的影响

采用中空纤维膜接触器(Hollow Fiber Membrane Contactor,HFMC)回收尿液中的氨氮,系统研究了吸收液类型(H3PO4、H2SO4和HNO3)对氨回收效能、水蒸气的跨膜通量和所获液体肥料的影响.结果 表明,使用H2SO4作为吸收液时氨氮回收效能最优,其次是H3PO4和HNO3.当采用H2SO...     

柴油低温临界吸收法回收装车挥发油气

研究了采用柴油低温临界吸收法回收装车挥发油气的效果。实验结果表明：按装车挥发油气中的总烃体积分数为20.88%、装车挥发油气流量为280 m³/h、年运行时间为2 668 h计,装置年回收油气量为291 t,装置年最大运行功率为206.770 MW,装置投资回收期为3 a;处理后净化气中的总烃体积分数为1.24%,排放质量浓度低于25 g/m³,油气回收率达95%。处理后净化气满足GB 20950—2007《储油库大气污染物排放标准》,取得了较好的环保效益和经济效益。