硅藻土用于钛白生产过滤的试验研究

从助滤原理和生产实验等方面阐述了硅藻土助滤剂代替木炭粉用于钛白生产的可行性。通过控制操作条件，研究对比了两种助滤剂的助滤性能。试验结果表明：硅藻土代替木炭粉作钛白生产助滤剂，不但能加快过滤速度，提高过滤质量，而且应用于生产中还可降低过滤成本，提高生产收率，降低工人的劳动强度。     

冬季黄河水预臭氧化中试试验

本试验采用臭氧为预氧化剂,以黄河水为水源水,对水源水中有机物（CODMn,UV254和TOC）、浊度、细菌总数、大肠菌群数、氨氮与亚硝酸盐氮等去除效果进行了试验研究。结果表明,预臭氧化使原水的浊度升高,但由于悬浮颗粒的状态发生变化,通过气浮、过滤处理后,浊度降低;预臭氧化有良好的杀菌作用;臭氧氧化可以去除部分有机物和亚硝酸盐氮,而且提高水中有机物的可生化性,提高后续工艺对污染物的去除率。     

New York City's Ozone Demonstration Plant Design

Designand construction specifications of a 3 mgd (12, 187 m³/day) demonstration plant to treat water by ozonation followed by diatomaceous earth (DE) filtration at New York City's Jerome Park Reservoir are described. The primary treatment objectives are to maintain a treated water quality of turbidity below 0.2 NTU, color below 3 color units, and iron and manganese below 0.3 mg/L. Three process trains will be employed, each operating at a maximum of 1 mgd (3,786 m³/day), to test variousmodificationsof theozone/DE process. The demonstration plant is scheduled to operate approximately one year, beginning in April 1986, to provide data for a full-scale plant to be constructed later in the decade.     

The Effects of Preozonation on the Biodegradability of Phenolic Solutions Using a New Gas-Inducing Reactor

To achieve effective COD removal, the combination of preozonation with biological treatment is necessary for phenolic wastewater treatments. Preozonation of 4-cresol, 2-chlorophenol and 4-nitrophenol solutions can be carried out with high ozone utilization rate using a new gas-inducing reactor. During the preozonation, the phenolic compounds can be completely decomposed with 100% ozone utilization rate. This new gas-inducing reactor is beneficial for the preozonation of phenolic solutions, comparing with a conventional gas-liquid reactor. The BOD₅ of preozonized phenolic solution is strongly related to both the degree of decomposition of phenolic compounds and the accumulation of intermediate products in aqueous solution. Based on the high ozone utilization rate, it is suggested that the optimal utilized ozone dose for 4-cresol, 2-chlorophenol and 4-nitrophenol can be chosen as 360, 350 and 400 mg/L, respectively. At those optimal utilized ozone doses, the ratio of BOD₅/COD of preozonized 4-cresol, 2-chlorophenol and 4-nitrophenol solutions increase to 0.33, 0.26 and 0.33, respectively.     

Water Quality Improvements with the Use of Ozone at the Los Angeles Water Treatment Plant

At 600 mgd (2,270 ML/day), the recently completed Los Angeles Aqueduct Filtration Plant (LAAFP) is one of the world's largest water' treatment facilities utilizing ozone for pretreatment. The treatment process features direct filtration at rates of up to 13.5 gpm/ft² (33 m/h). Under the optimized full-scale operation, preozonation has resulted in significantly reduced THM levels and very low effluent turbidity with low operating costs.     

The Preozonation of Phenolic Aqueous Solution and Its Effect on the Improvement of Coagulation Treatment

Phenolic solutions are difficult to treat with coagulation processes because phenol is well soluble in water. However, with suitable preozonation, the ozonized organic components can be removed more effectively by coagulation processes. In order to avoid excessive preozonation, a good control on the degree of preozonation is crucial for practical applications. The degree of preozonation of phenolic solution was evaluated by measuring the phenol decomposition rate, ADMI value and ozone outlet concentration during the ozonation. Three characteristic times were observed, namely (1) ADMI value reaches the peak value during preozonation, (2) the ozone outlet concentration starts increasing, and (3) the ADMI value reaches the discharge standard (500 value, EPA Taiwan). These characteristic times provide the useful means as real-time control parameters on the extent of preozonation. The results of HPLC and GPC show that phenol is almost completely decomposed after 43?min of preozonation. The major components after preozonation are oxalic acid and coupling compounds. The preozonized solution, containing phenol decomposition products, was then subjected to coagulation treatments. The coagulation behavior of preozonized solution is dependent on the extent of preozonation. Three types of coagulant were investigated, namely alum, ferric chloride (FeCl₃) and poly aluminum chloride (PAC). Both PAC and FeCl₃ are effective coagulants for COD removal. As an example, phenol solution (initial phenol concentration=300?mg/L, C _{O 3},i=20?mg/L) was preozonized for 50 minutes, followed by FeCl₃ coagulation treatment. After preozonation and coagulation processes, the total COD and ADMI removal rates are as high as 70% and 80%, respectively. Most of the coupling compounds and oxalic acid are removed by the coagulant.     

Preparation of Hydrothermally Solidified Mesoporous Materials from Diatomaceous Earth for Moisture Control Application

Mesoporous materials were prepared by hydrothermal treatment of a powder compact consisting of natural or calcined diatomaceous earth and slaked lime. Tobermorite formed after the hydrothermal process, leading to strength improvement. The structure tangled with each tobermorite particle, causing the formation of mesopores. The bending strength and mesopore volume of the hydrothermally solidified materials derived from calcined diatomaceous earth was much higher than those derived from natural diatomaceous earth. Impurities in the natural diatomaceous earth suppressed the crystallization and growth of tobermorite, which plays an important role in strength improvement and mesopore formation. Water vapor adsorption–desorption isotherms showed that the amount of adsorbed moisture on the two kinds of hydrothermally solidified materials was almost the same.     

Advantages of Preozonation in the Upgrading of the Mont Valérien Plant in France

The Mont Valérien plant supplies water to the western suburbs of Paris. Raw water comes from the River Seine downstream from the city. The old plant comprised two treatment lines: a slow sand filtration line built 80 years ago and a rapid settling and filtration line built in 1960. The process for the upgraded plant was determined after an in-depth study including industrial-scale experiments and laboratory tests.

The new treatment line includes the following: preozonation, oagulationflocculation and settling in a sludge-blanket type settling tank (PULSATOR), rapid gravity sand filtration, ozonation, and granular activated carbon filtration.

Results from laboratory tests used for the design are presented: ozonation rate, advantages for the quality of the treated water, expected reagejit savings, etc.     

Use Of Ozone And Flotation For The Treatment Of A Reservoir Water: The Dinan Case History

The plant of Dinan supplies water to the urban district of Dinan (Brittany-France). The raw water is a dam water, soft, containing iron and manganese, highly colored with a high content of organic carbon. The area providing water to the dam is rural country, so water also contains residues of agricultural practices such as pesticides and nitrates.

During summer, algae blooms may occur. The old plant (including prechlorination, coagulation, flocculation, settling and sand filtration) has been replaced with a treatment line including: remineralization, preozonation, flotation, ozonation and granular activated carbon. Nitrate removal will be considered in the future. The paper presents the results obtained in the plant, the optimization of the preozonation dose as well as comparison with laboratory tests. A special reference concerns algae removal.     

Effect of Ozonation on Trihalomethane and Haloacetic Acid Formation and Speciation in a Full-Scale Distribution System

Disinfection by-product (DBP) formation was evaluated before and after ozone implementation at two full-scale drinking water facilities in Las Vegas, NV USA. The two treatment plants used preozonation for primary disinfection followed by direct filtration with subsequent chlorination for secondary disinfection. DBP data was evaluated from the finished water of the two treatment plants along with six locations in the distribution system. Results showed that preozonation reduced the formation of total trihalomethanes (TTHM) by up to 10 μg/L and the sum of five haloacetic acids (HAA5) by up to 5 g/L. These reductions were primarily due to decreases in the di- and trichlorinated DBPs such as chloroform, bromodichloromethane, and trichloroacetic acid. Ozonation appeared to shift the speciation of TTHMs and HAA5 to favor increased formation of the di- and tribrominated species such as bromoform, chlorodibromomethane, and dibromoacteic acid. A bromide mass balance showed that <30% of the raw water bromide was accounted for by the formation of TTHMs (8–21%), HAAs (2–3%) and bromate (5%). Reducing the concentration of THMs and HAAs is often not the primary purpose of ozonation, but it can assist utilities in meeting regulatory requirements during drinking water treatment.     

The pretreatment of seawater RO feed using the UVOX (UV/oxidant) process

The UVOX process, which is essentially the retention of chlorinated (or conceivably ozonated) seawater for a period of about 3 days in open ponds, has been developed and proved to be effective in improving the treatability of nutrientrich recalcitrant seawater, to the extent that simple sand filtration and/or diatomaceous earth filtration will yield a feedwater, for RO desalination, with a plugging index of less than 45 per cent. The process eliminated the need for chemical coagulation and relatively expensive clarification systems.     

Ozonation of Drinking Water: A Design Methodology

The formation of potentially carcinogenic organic halides has been shown to result from drinking water disinfection with chlorine. xidative treatment of organic halide precursors with ozone prior to chlorination has surfaced as an attractive technique for reducing the formation of these compounds. In addition to reduction of precursor levels, preozonation has been reported to effect other beneficial results in water treatment. This paper presents design methodologies to optimize the implementation of the ozonation process for water treatment applications. Pre-design considerations common to all ozonation design processes are discussed. Subsequently, design procedures for the ozone generation and contacting systems are reviewed.     

VB12发酵液过滤特性研究及分离优化

对VB12发酵液进行絮凝预处理,由正交实验确定影响絮凝的主要因素,结果表明,最佳絮凝条件:絮凝剂为聚合氯化铝、加入体积分数7%、pH值6、搅拌速度140 r/min、搅拌时间45 s。通过加压过滤实验,得到絮凝后滤饼的过滤特性;在此基础上,加入硅藻土助滤剂以探讨对滤饼结构和过滤速率的影响,并考察滤饼的比阻值及可压缩性。实验表明:絮凝预处理后的滤饼为高可压缩滤饼,加入硅藻土后滤饼的比阻值降低,可压缩性系数减小到0.387,过滤速率提高30%。     

提高相变材料十四酸导热性能的研究

利用时间—温度曲线法对13组十四酸-硅藻土体系的导热系数进行了测定,得到了十四酸添加不同量硅藻土的导热系数变化关系曲线,硅藻土的添加量应≤15%。通过添加硅藻土,相变材料十四酸的热传导热性能有了较大的改善。     

Optimization and Control of Ozonation Plant Using Raw Water Characterization Method

This study was undertaken to devise an innovative method for optimization and control of ozone dosage in drinking water ozonation treatment plants. The method is based upon a specifically-conceived analytical procedure, which can accurately measure the ozone decomposition rate. This was found to consist of two apparent phases: an instantaneous ozone demand (ID) phase and a relatively slower ozone decay (pseudo first-order rate constant, kc) phase. Those parameters, ID and kc were measured in a demonstration plant by the testing procedure in order to characterize raw water and process water, and utilized an Automatic Ozone Control Unit (ACU) to optimize preozonation (with parameter, ID) and postozonation (with parameter, kc).     

硅藻土-木桨纤维为助滤剂强化过滤过程的研究(英文)

In this paper, a study to enhance the filtration for solid/liquid materials difficult to be filtered, such as highly viscous, highly compactible or gel like materials, is presented. Filter aids diatomaceous earth and wood pulp cellulose are used to enhance the filtration by improving filter cake structure and properties in the filtration of a biological health product and a highly viscous chemical fiber polymer melt product. The property of solid/liquid systems, filtration at different flow rates, specific cake resistance, cake wetness, filtration rate, filtrate turbidity for filter aid selection and evaluation, and operation optimization are investigated. The results are successfully applied to industrial process, and can be used as a reference for similar filtration applications.     

Regeneration of oils used for deep frying: A comparison of active filter aids

A number of products are promoted for the purpose of regenerating used frying oils. These materials are referred to as “active” filter aids. They are purported to adsorb polar compounds, which are the products of oil degradation, and to retain them for removal by filtration. To evaluate some of these materials, portions of a used oil were treated with each of several “active” filter aids and filtered in a commercial-type recirculating oil filter. The triglycerides and any adsorbed compounds were extracted from the filter cake with a series of increasingly polar organic solvents. The composition of each of the filter cakes was quantitatively determined. The materials tested in this study were diatomaceous earth, acid-activated bleaching earth, activated aluminas, silica, carbon and synthetic magnesium silicate. Significant differences in the adsorbent characteristics of the materials were found. Adsorption of polar oil degradation compounds ranged from 2 mg of polar compounds per gram of diatomaceous earth to about 200 mg/g magnesium silicate.     

Flocculation Effects of Ozone

There are numerous reports on coagulation/flocculation effects of preozonation, which cannot be interpreted by one single mechanism. About 7 basic processes are presently discussed. This paper presents results from drinking and wastewater treatment, indicating that preozonation effects can be explained with algae flocculation, with the destabilization of particles, and with polymerization of the dissolved organics. In view of the complexity of the systems, it is anticipated that several processes can be responsible, leading to an optimum ozone dosage.     

Organic filter media offered as an alternative to DE

The Arbocel^® product range of organic filter media are being introduced to the UK and Irish markets by Allchem International Ltd. They are intended as an alternative to diatomaceous earth (DE) or perlite filter media products.This is a short news story only. Visit www.filtsep.com for the latest filtration industry news.     

改性硅藻土调理剩余污泥沉降性能

利用传统无机絮凝剂对硅藻土进行改性,对污水厂剩余活性污泥进行预处理。结果表明,污泥沉降比随改性硅藻土投加量的增加而减小。从技术和经济角度考虑,改性硅藻土的较佳投配量为：每升污泥投加硅藻土1．0g,混合药剂0．33g。