Effect of Ferric Chloride on the Properties of Biological Sludge in Co-precipitation Phosphorus Removal Process

This paper studied the effect of ferric chloride on waste sludge digestion,dewatering and sedimentation under the optimized doses in co-precipitation phosphorus removal process.The experimental results showed that the concentration of mixed liquid suspended solid(MLSS) was 2436 mg.L-1 and 2385 mg.L-1 in co-precipitation phosphorus removal process(CPR) and biological phosphorous removal process(BPR),respectively.The sludge reduction ratio for each process was 22.6% and 24.6% in aerobic digestion,and 27.6% and 29.9% in anaerobic digestion,respectively.Due to the addition of chemical to the end of aeration tank,the sludge content of CPR was slightly higher than that of BPR,but the sludge reduction rate for both processes had no distinct difference.The sludge volume index(SVI) and sludge specific resistance of BPR were 126 ml.g-1 and 11.7×1012 m.kg-1,respectively,while those of CPR were only 98 ml.g-1 and 7.1×1012 m.kg-1,indicating that CPR chemical could improve sludge settling and dewatering.

A mathematical model for electrochemical chloride removal from marine cast iron artifacts

The aim of this article was to theoretically study diffusion and migration of chloride ions during electrochemical chloride removal. The proposed model would enable optimization of its application by predicting the optimal treatment time and current combination. A mathematical model for simulating the transport behavior of chloride ions was developed by consideration of diffusion and migration of chloride ions when a constant DC current density was applied through the marine cast iron artifacts. The corresponding tests were conducted to validate the mathematical model. This model predicted the data of the extraction ratio of the chloride ion that correlated satisfactorily with the experimental values. An important issue in electrochemical chloride removal was to understand how chloride ions moved, taking account of diffusion and migration of chloride ions and the release of binding chloride ions. The effects of the treatment time, externally applied current density, chloride diffusion coefficient, and rate constant of release of binding chloride ion on chloride removal are studied. The specific quantitative details applied to one-dimensional model were discussed here. This article has proposed a mathematical model for the first time, which was showed to be a useful tool that can reveal the ionic transport mechanism and optimize the application during electrochemical chloride removal.

On-line Monitoring for Phosphorus Removal Process and Bacterial Community in Sequencing Batch Reactor

For efficient energy consumption and control of effluent quality, the cycle duration for a sequencing batch reactor (SBR) needs to be adjusted by real-time control according to the characteristics and loading of waste-water. In this study, an on-line information system for phosphorus removal processes was established. Based on the analysis for four systems with different ecological community structures and two operation modes, anaerobic-aerobic process and anaerobic-anaerobic process, the characteristic patterns of oxidation-reduction potential (ORP) and pH were related to phosphorous dynamics in the anaerobic, anoxic and aerobic phases, for determination of the end of phosphorous removal. In the operation mode of anaerobic-aerobic process, the pH profile in the anaerobic phase was used to estimate the relative amount of phosphorous accumulating organisms (PAOs) and glycogen accumulat-ing organisms (GAOs), which is beneficial to early detection of ecology community shifts. The on-line sensor val-ues of pH and ORP may be used as the parameters to adjust the duration for phosphorous removal and community shifts to cope with influent variations and maintain appropriate operation conditions.

Phosphorus removal by adsorbent based on poly-aluminum chloride sludge

Phosphorus adsorption tests were carried out using poly-aluminum chloride sludge(PACS),which was collected from a water treatment plant in Nanjing.The amount of phosphorus adsorbed by PACS increased quickly within the first hour and reached equilibrium after about 48 h.The adsorption behavior of PACS for phosphorus is consistent with the Langmuir adsorption isotherm equation(R2>0.99)and parallel first-order kinetic equation(R2>0.98).With the increase of the PACS concentration,the adsorption capacity of PACS for phosphorus decreased,and the removal rate increased.The results of batch tests showed that the adsorption capacities of PACS for phosphorus ranged from 1.64 to 1.13 mg/g when the pH value varied from 4 to 10.However,the adsorption capacity of PACS was not evidently influenced by temperature.In comparison with the ion exchange resin,the adsorption capacity of PACS was barely inhibited by competitive ions,such as SO2
4,NO
3,and Cl
.The PACS surface after adsorption became smooth,and the vibration peaks of AleO and AleOH shifted.Both HCl and NaOH have a strong desorption effect on PACS after adsorption saturation,and with higher concentrations of HCl and NaOH,the desorption effect was stronger.Results of column adsorption experiments showed that with lower phosphorus and hydraulic loads,the adsorption column took longer to reach saturation.This indicated that PACS could be used as an efficient material for removal of phosphorus from water.This study provides a new treatment method with PACS.

Effect of reprocessing on neutrons of a molten chloride salt fast reactor

Due to their unique features,such as the inherent safety,simplified fuel cycle,and continuous on-line reprocessing,molten salt reactors(MSRs)are regarded as one of the six reference reactors in the Generation IV International Forum(GEN-IV).Molten chloride salt fast reactors(MCFRs)are a type of MSR.Compared to molten fluoride salt reactors(MFSRs),MCFRs have a higher solubility of heavy metal atoms,a harder neutron spectrum,lower accumulation of fission products(FPs),and better breeding and transmutation performance.Thus,MCFRs have been recognized as a type of MSR with great prospects for future development.However,as the most important feature for MSRs,the effect of different reprocessing modes on MCFRs must be researched in depth.As such,this study investigated the effect of different isotopes,especially FPs,on the neutronic performance of an MCFR,such as its breeding performance.Furthermore,the characteristics of the different reprocessing modes and MCFR rates were analyzed in terms of safety,radioactivity level,neutron economy,and breeding capacity.In the end,a reprocessing method suitable for MCFRs was determined through calculation and analysis,which provides a reference for the further research of MCFRs.

Comparison of Three Aluminum Coagulants for Phosphorus Removal

That phosphorus has been removed more from water in purification process can result in higher grade of biological stability of the effluent tap water, especially for the water plant when using surface water source. This study conducted the experiments of phosphorus removal by three coagulants including aluminum chloride, aluminum sulfate and poly aluminum chloride. The results indicated that the poly aluminum chloride is the preferred one that could remove phosphorus up to 80%, followed by aluminum chloride and aluminum sulfate. The lowest proportion of aluminum quality to phosphorus quality is 63 as using poly aluminum chloride, followed by aluminum chloride and aluminum sulfate. It is suggested that the poly aluminum chloride should be the best option to remove phosphorus in water plant.

原油中有机氯盐的分析与脱除

针对某炼油厂电脱盐后原油含盐超标的问题,对原油样品进行了蒸馏切割,分析了各馏分段的有机氯和无机氯含量,并对柴油馏分的含氯化合物形态进行了分析;采用GC-MS和GC-NCD方法分析了溶于水中的含氯化合物和反萃取相中的极性含氮化合物,从而确定了柴油馏分段的含氯化合物的主要成分为喹啉盐酸盐,并推断其为原油中难脱除氯盐。通过向原油中加入喹啉盐酸盐进行蒸馏切割实验和脱盐实验,证实了喹啉盐酸盐可以进入柴油馏分,并导致脱盐实验的脱后油含盐升高。采用有机胺类化合物研制了脱盐剂C,并对实际原油进行了脱盐实验,结果表明,与未加入脱盐剂C(原油中总氯和盐质量分数分别为18 mg/kg和10 mgNaCl/kg)相比,脱盐剂C加入质量分数高于50 mg/kg时,脱后原油总氯和盐质量分数分别低于7.9 mg/kg和3.1 mgNaCl/kg。

脉冲电流对电化学除氯的影响

目的探究不同电流密度下,直流和脉冲2种电流模式对钢筋混凝土电化学除氯的影响,降低钢筋渗氢量,减小通电后阴极产生的氢气使钢筋发生氢脆的风险,提高除氯效率,改善电化学除氯效率的均匀性。方法通过在电流密度为2、3、4A/m2的条件下,对混凝土进行直流和脉冲电流电化学修复,测定处理后的钢筋的释氢电流,计算释氢总电量,来表示钢筋渗氢量,对比处理后强电流区和弱电流区混凝土的氯离子含量,分析2种方式除氯效率的均匀性,同时用扫描电子显微镜观察电化学除氯前后混凝土的微观结构。结果计算得到不同通电电流密度下钢筋的释氢总电量和除氯效率,脉冲电流的释氢总电量比直流电流低约20%,而除氯效率提高了约10%。结论增加电流密度可以提高除氯效率,但是会增加钢筋发生氢脆的风险。相较于直流电流,脉冲电流电化学修复可以降低钢筋渗氢量,显著提高弱电流区的除氯效率,从而改善除氯效率的均匀性。

改性沸石/聚合氯化铝造粒复合材料对水中氨氮和磷的吸附性能研究

以改性沸石(MZ)和聚合氯化铝(PAC)为原料,添加粘结剂聚乙烯醇(PVA)和造孔剂碳酸氢钠(NaHCO_(3)),制备出可同步脱氮除磷的复合颗粒材料(MZP),并探究了投加量和pH等因素对氨氮和磷吸附性能的影响。结果表明,在MZP投加量为7 g/L,pH为6~8条件下,MZP对氨氮和磷的去除率均高于84%。MZP对氨氮和磷的吸附符合Freundlich吸附等温线模型,且吸附过程受液膜扩散和颗粒内扩散共同控制,符合准二级动力学模型,吸附过程MZP对氨氮和磷的最大理论吸附量分别为5.92、2.25 mg/g。共存离子对MZP吸附氨氮和磷有一定影响。经过5次吸附-解吸再生循环利用后,MZP仍能保持74%的氨氮去除率和52.6%的磷去除率。结合材料表征分析结果,MZP对氨氮的吸附主要为离子交换,对磷的吸附主要为静电吸附和配体交换。

聚合氯化铝强化某医院污水处理效果研究

文章以某医院二沉池出水作为研究对象,选择聚合氯化铝(PAC)为混凝剂,通过烧杯实验模拟实际操作条件,考察投药量和pH值对处理效果的影响。研究结果表明,当PAC投加量为25 mg/L时,出水TP可以达到GB 18918—2002《城镇污水处理厂污染物排放标准》中的一级B标准,COD_(Cr)可以达到一级A标准,NH_(3)-N的去除效果仅能达到二级标准;碱性条件有利于UV_(254)的去除,而在PAC的有效pH值范围内对TOC去除效果最佳的pH值为5,且TOC的去除率随着PAC投加量的增加而增加;pH值对SUVA的影响主要是通过去除水中具有紫外吸收特性的有机物实现,而PAC投加量则主要是通过去除水中腐殖质及具有碳碳双键、芳香环结构的有机物对出水SUVA值产生影响。

不同混凝剂对藻类的去除效果研究

以小球藻为研究对象,研究了硫酸铝、聚合氯化铝(PAC)、聚合硫酸铁(PFS)在不同投加量、pH值以及高锰酸钾预氧化条件下对藻类去除效果的影响。结果显示,PAC对藻类去除效果最佳,当PAC投加量为25 mg/L、pH值为8.0、高锰酸钾的使用量为0.8 mg/L、预氧化时间为30 min时,此条件下对小球藻的去除率可以达到93.73%。

聚合氯化铝铁除磷试验研究

以某城市污水厂生化出水为研究对象,通过试验研究聚合氯化铝铁中Al_(2)O_(3)与Fe^(3+)的含量变化对除磷效果的影响。同时,研究了聚合氯化铝铁的投加量对除磷效果的影响。结果表明:聚合氯化铝铁中Al_(2)O_(3)含量为9.0%,Fe^(3+)含量为0.8%时处理效果最佳。而出水的聚合氯化铝铁药剂用量在120 mg/L时,TP出水浓度为0.09mg/L,可确保污水厂出水总磷TP≤0.10mg/L的内控排放标准。

聚合氯化铝-聚丙烯酰胺处理含氟废水研究

使用聚合氯化铝(PAC)-聚丙烯酰胺(PAM)联合处理含氟废水,考察了PAC投加量、PAM浓度、pH值、反应时间以及搅拌速度对除氟效果的影响。结果表明,在PAC投加量4400 mg/L、PAM浓度1 mg/L、溶液pH值7.0、反应时间20 min、搅拌速度300 r/min时,氟去除率达97.98%,除氟后溶液中氟离子残余浓度为0.81 mg/L。溶液中杂质离子的存在会降低PAC的除氟性能。

污水厂应用除磷药剂的比较研究

以分别在聚合氯化铝和硫酸铝作用下的活性污泥为研究对象,在投加一定量磁粉的前提下,分别考察了不同投药量(0.04、0.06、0.08、0.1 mg/L)下的硫酸铝和聚合氯化铝与梯度投药量(0.2、0.3、0.4 mg/L)下的PAM对污泥沉降性及出水上清液SS和TP的影响并且在此基础上进行成本估算。

海洋环境下预除氯海水拌制钢筋混凝土构件可行性

考虑岛礁建设中拌和混凝土的需要,本文提出采用工业污水除氯中常用的超高石灰铝法对模拟海水进行预除氯。探讨了除氯反应所需较优反应物料比例、较优反应时间及反应温度和二次除氯对除氯效果的影响;采用预除氯海水拌和混凝土试件,评估了混凝土的抗氯离子渗透性能、力学性能和预除氯混凝土中普通钢筋的抗腐蚀性能。结果表明:与模拟海水拌和的混凝土试件相比,预除氯海水在环境条件下的前期对混凝土的抗氯离子渗透性能有一定改善;降低水胶比可有效提高混凝土的抗氯离子渗透性能;在模拟海洋干湿循环下、预除氯海水混凝土试件中,普通钢筋在干湿循环的前4个周期表现出较优的抗腐蚀性能。因此,在海洋环境中采用超高石灰铝法对海水进行预除氯并用于浇筑钢筋混凝土构件是可行的。

PAC-PAM联合处理汽车织布废水的应用研究

研究了聚合氯化铝(PAC)和聚丙烯酰胺(PAM)单独以及联合处理汽车织布废水,考察了净水剂投加量、pH值和温度三个重要因素对纺织废水中COD_(Cr)去除效果的影响。结果表明PAC与PAM联合使用去除COD_(Cr)的效果要明显优于单独使用的效果;PAC与PAM联合使用时最佳的pH值为7~9,适宜的水温为20~40℃,可在较小的投加量(PAC 50.0 mg/L,PAM 3.0 mg/L)下实现较高的去除效率(80%)。上述实验研究可为实际工程应用中混凝沉淀提供工程应用数据支持。

水溶液隔膜电解除铁

在用高铝粉煤灰盐酸法制备氧化铝的过程中,粉煤灰中的铁会随酸性浸出液进入氯化铝溶液.为了低成本降低氯化铝溶液中铁杂质的质量分数,提出了在水溶液中电解除铁的方法.除铁实验中使用双室隔膜电解槽,对初始条件为pH值2.0,Fe^(2+)质量分数0.25%的FeCl_(2)溶液进行循环电解,研究了几种常见金属阴极板上单质铁的析出效果.结果表明:使用钛、铁、锡、铜、铅5种金属电极均可在5 h电解后达到90%的除铁率,溶液中亚铁离子的质量分数降低至小于0.03%.

河南某金矿尼尔森重砂催化盐酸除杂试验

为了提高河南某金矿选矿厂尼尔森重砂的金销售计价系数,在对尼尔森重砂性质研究的基础上,对多种有机酸除杂原理对比分析,确定了盐酸除杂试验路线,并通过单因素条件试验,确定了氯化钠催化盐酸除杂的最佳试验条件。结果表明:当盐酸浓度为3 mol/L,氯化钠浓度为4 mol/L,反应温度为90℃,液固比为10∶1,反应时间为1.5 h时,除杂率最优。并在此基础上进行了最佳条件综合试验,尼尔森重砂金的含量从18.88%提高至55.5%,除杂率达65.98%,销售时金的计价系数可由94%提高至96%,每年预计增加经济效益400余万元。

一种高效复合除氟剂及其在高盐废水中除氟的研究

一种高效复合除氟剂包含聚合氯化铝、六水氯化铝、硫酸铝以及硫酸锌等有效成分,按质量百分比计含聚合氯化铝70%~80%,六水氯化铝5%~10%,硫酸铝5%~10%,硫酸锌0.1%~1.0%。使用方法为将高效复合除氟剂配置成500 g/L的溶液,加入氟离子初始浓度为10.6 mg/L的高盐废水中,经过搅拌后沉淀,调节终点pH在7.0左右,氟化物去除率高达95%以上,可达到出水指标1.0 mg/L以下。