用弗雷德盐沉降去除水体中镉的絮凝形态

用微/纳结构的弗雷德盐乳液作吸附-絮凝剂以絮凝法去除水体中重金属镉。结果表明,弗雷德盐絮凝沉降镉的去除率达97.8%。背散射与点能谱的研究表明,弗雷德盐在水处理过程中经历了溶解-再结晶,形成稳定性更高的六方柱形方解石和无定型氢氧化铝。水体中部分镉离子吸附或共沉淀在六方柱形方解石表面;另有部分镉离子吸附或共沉淀在水解生成的无定形氢氧化铝胶体中。XRD谱图比较证实,还有部分镉以类质同象取代方解石中的钙进入晶格。     

云南晋宁磷矿浮选废水处理研究

在磷矿的正反浮选中,由于矿浆不同的pH值条件,磷矿石的多样性,矿浆中无机离子及药剂组份表现出不同的特性,正浮选尾矿水、反浮选精矿水及反浮选尾矿水差异性很大,将所有选矿废水集中收集,不经处理统一回用显然是行不通的。絮凝沉淀法是处理晋宁磷矿浮选废水的有效方法之一,石灰与碳酸钠或磷酸钠配合使用都可以用来处理浮选废水。当氧化钙用量为4.0 kg/m3、碳酸钠用量为0.6 kg/m3时,闭路流程试验最终精矿w(P2O5)=29.66%,回收率达77.38%;当氧化钙用量为2.0 kg/m3、十二水磷酸钠用量为0.2 kg/m3时,最终精矿w(P2O5)=30.22%,回收率76.74%。此方法处理后的废水回用对浮选过程影响不大,且简单易行,工业上容易实施。     

Influence of Hydrophobicity on Agglomeration of Dolomite in Cationic-Anionic Surfactant System

In this study the modified procedure of the oil agglomeration process was carried out, where the emulsion of dodecylammonium hydrochloride (DDAHCl) solution and kerosene was added to the mineral suspension. The aim of this work was to research the oil agglomeration of dolomite mineral by the contact angle, zeta potential and surface free energy measurements. The relationship between the investigated parameters and the oil agglomeration as well as shear flocculation was revealed. The mechanism of oil agglomeration of hydrophilic particles in cationic-anionic surfactant system has been proposed. It was concluded that oil droplets interact rather with aggregates of particles modified by anionic surfactant than the single mineral particles as was explained for naturally hydrophobic particles.     

Flocculation of spin bath NMMO solution for removal of colloidal impurities in lyocell process

ABSTRACT

Evaluation of various flocculants, selection of suitable flocculant and optimization of process parameters for reduction of colloidal particles have been carried out for lyocell spin bath solution. Maximum turbidity reduction was achieved with polyacrylamide based flocculant. Experiments were carried out using lab jar tests and factorial design of experiment was applied to optimize the flocculation process parameters, i.e., flocculant dosage, mixing time and mixing speed. Operation at optimum conditions reduced turbidity by 80–90% and improved the downstream operation of ion-exchanger by 11%. Without flocculation treatment, surface fouling of ion-exchange resin was observed in Scanning Electron Microscopy.     

A Review of the Use of Chitosan for the Removal of Particulate and Dissolved Contaminants

Abstract

Chitosan has unique properties among biopolymers, especially due to the presence of primary amino groups. Chitosan has been used for the chelation of metal ions in near‐neutral solution, the complexation of anions in acidic solution (cationic properties due to amine protonation), the coagulation of negatively charged contaminants under acidic conditions, and for precipitative flocculation at pH above the pKa of chitosan. The coagulation and flocculation properties can be used to treat particulate suspensions (organic or inorganic) and also to treat dissolved organic materials (including dyes and humic acid). This paper will give an overview of the principal results obtained in the treatment of various suspensions and solutions: (a) bentonite suspensions; (b) organic suspensions; (c) anionic dye solutions; and (d) humic acid solutions. Stoichiometry and charge restabilization were determined for the coagulation of humic acid, kaolin, and organic dyes with chitosan, indicating charge neutralization as the dominant mechanism for removal. Charge patch destabilization and bridging mechanisms were inferred in other cases, based on the effects of the apparent molecular weight of the chitosan preparations and effectiveness of sub‐stoichiometric doses of chitosan. For dye solutions, results showed that color can be removed either by sorption onto solid‐state chitosan or by coagulation‐flocculation using dissolved‐state chitosan; the reactivity of amine groups was significantly increased when dissolved chitosan was used. For humic materials, chitosan can be used as a primary coagulant or as a flocculant after coagulation with alum or other inexpensive coagulants. The influence of the degree of deacetylation and the molecular weight of chitosan on its performance as coagulant/flocculant is illustrated by several examples.     

Sludge Dewatering and Aggregate Formation Effects through Taylor Vortex Assisted Flocculation

Abstract

For polymer induced flocculation processes, the effects of flow patterns in a gap of a conical stirrer on aggregate formation and subsequent sludge dewatering efficiency were analysed. Different flow regimes were identified by lab scale investigations with model substances and summarized in a Ta and Re number plane. An enhancement of sludge dewaterability for polymer induced flocculation processes was identified through post‐treatment of flocculated sludge aggregates by the specific flow pattern of stable and wavy Taylor vortices. Photo‐optical image analysis of flocculated aggregates shows a clear change of aggregate size distribution with less small particles during aggregate forming by Taylor vortices compared to classical flocculation procedure by stirrer. Results from technical scale dewatering analyses confirmed enhancement of sludge dewatering efficiency for six different dewatering machines using the identified wavy and stable Taylor vortex flow pattern regime.     

Separation of Contaminants from Deinking Process Water by Dissolved Air Flotation: Effect of Flocculant Charge Density

Abstract

The effect of charge density of 5 cationic polyacrylamides (C-PAMs) and 3 anionic polyacrylamides (A-PAMs) in single and in dual treatments with a coagulant on the flocculation and removal of dissolved and colloidal material by dissolved air flotation (DAF) in papermaking has been studied. In single systems, good results were achieved both with low and high charge C-PAMs (1.0 and 3.0–3.5 meq/g). In dual systems, high charge C-PAMs (3.0–3.5 meq/g) and A-PAMs (1.5 meq/g), were the most efficient. Results show that monitoring flocculation by a focused beam reflectance measurement (FBRM) allows papermakers to optimize the chemical dosages to maximize the separation efficiency of DAF units either with single or dual systems, which is not always possible with traditional methods as charge titration.     

Operating Conditions Corresponding to Optimal Final Properties of Activated Sludge Using the DOE and RSM Techniques

Abstract

This paper presents the influence of four relevant factors on the flocculation behavior in the activated sludge process: organic loading rate (COD), solid retention time (SRT), dissolved oxygen (DO), and calcium ion concentration, and links them to a selected set of process responses: sludge volume index (SVI), turbidity, organic removal rate (COD), and suspended solids (SS) removal. The “Design of Experiments” (DOE) and the “Response Surface Methods” (RSM) approaches are used to establish the operating conditions corresponding to optimal final properties of the activated sludge. Using these techniques, the results show that it is indeed feasible to locate the operating conditions which optimize the flocculation process and the sludge settling properties. The study represents a first attempt to evaluate the flocculation process in activated sludge using the DOE/RSM approach.     

实验室废水处理方法综述

文章综述了实验室废水处理方法,重点介绍了絮凝沉淀法、氧化法、膜处理法的研究进展,并总结了目前实验室废水处理中存在的问题,为今后实验室废水的处理提供参考。     

高浓度日用化工废水处理研究

采用二级接触氧化–Fenton试剂法深度处理日用化工生产废水,研究结果表明：一级好氧生化段出水CODCr由276～436 mg/L降到200～275mg/L以下,物化处理段采用Fenton化学氧化和絮凝沉淀去除残存的难降解有机物,CODCr除率达65%,最终出水CODCr达到广东省地方标准《水污染物排放限值》（DB44/26-2001）第二时段一级标准。