卧螺离心机在水厂藻类气浮污泥脱水中的应用

本文着重介绍了卧螺离心机在水厂采用气浮法产水过程中产生的藻类气浮污泥的脱水处理。阐述了卧螺离心机在这方面应用较其它脱水装置的优势,并列举了水厂处理污泥的实例,得出了卧螺离心机的转速、高分子絮凝剂投加量以及螺旋差速同脱水泥饼含固率之间的关系,根据这一系列的关系,可知卧螺离心机在使用时的最优参数。     

卧螺离心机脱水改浓缩结构改造

卧螺离心机因无法直接达到污泥含固要求而正在退出污水处理领域。将卧螺离心机进行脱水改浓缩的结构改造,使系统完成浓缩工序,不仅降低了污水厂改造成本,而且有效再利用了厂区原有的设备资源。     

卧螺离心机含油污泥脱水试验研究

石油钻井以及某些其他工业领域中的含油污泥是一种较难脱水的污泥。2003年10月新疆油田选用了卧螺离心机以及成套设备用于这种含油污泥脱水,经使用已获得了很好的效果,其固相回收率达99%以上。从而为国内含油污泥脱水提供了成功的经验和理想的设备。     

UCA501-00-32型卧螺离心机在中山某污水处理厂污泥脱水系统中的应用

介绍了UCA501-00-32型卧螺离心机的结构及其工作原理,并针对四种影响因素,阐述了其污泥脱水的优越性。结合中山某污水处理厂一、二期工程实践经验,具体分析了UCA501-00-32型卧螺离心机的运行特点。并根据应用实践总结了卧螺离心机稳定运行的调整方法。投入使用期间污泥效果良好,泥饼含水率从99.4%降为80%以下,达到了节能减排的优良功效,可作为示范工程,具有推广价值,为今后珠三角各污水处理厂排泥处理的工艺设计、设备选型、仪表配制及运行模式提供了参考经验和科学依据。     

油田污泥离心脱水减量处理现场试验

为了保证注水水质达标,油田污水站采用连续排泥工艺降低悬浮物和泥沙的含量,由此产生大量含水率高的污泥,造成运输费用及后续无害化处理费用的增加,因此,需要对污泥进行减量处理。以卧螺离心机为关键设备,设计了1套污泥离心脱水减量工艺。通过现场试验得到转速、差速、絮凝剂投加量、温度对减量效果的作用规律。在一定范围内,转速越高、差速越低、絮凝剂投加量越大、温度越高,处理后的污泥含水越少。采用正交试验方法优化得到工艺最佳运行参数:转速为2 500 r/min,差速为9 r/min,加药量为225 g/m3,温度为55℃。处理后,平均含水率从入口的97.37%下降到出泥口的59.17%,平均含固率从入口的1.73%上升到出泥口的33.72%。离心机出水口和出泥口分流比范围为24.14∶1~33.19∶1,对应的污泥减量比例为96.02%~97.08%,污泥减量效果很好。     

国外压榨式卧螺沉降离心机的发展概况

针对用于污泥脱水的普通卧螺沉降离心机沉渣含湿量高的问题，国外开发出了一种压榨式卧螺沉降离心机，沉渣含湿量可降低５～１０％。本文简要地叙述了国外近年来对这种新型离心机的试验研究、结构设计和应用等情况。     

不锈钢冷轧废水站污泥脱水系统

介绍了采用板框压滤机处理不锈钢冷轧废水重金属污泥的工艺。设计泥量(以干污泥计)24 t/d,各水处理子系统的污泥,主要以含酸废水处理系统的污泥为主,泵入污泥浓缩池浓缩后,含固率8%～10%的污泥通过变频器控制的偏心单螺杆泵输送至板框压滤机。经过板框压滤机脱水后的泥饼含固率要求大于35%。系统自2007年9月初调试正常以来,运行良好,泥饼含固率稳定在35%以上。     

卧螺离心机设计选型中应注意的几个问题

介绍了卧螺离心机污泥脱水系统的组成及其整体集成性能,并结合调试和应用经验,对卧螺离心机设计选型中应注意的一些问题如工艺管线的布置、离心机处理能力的确定、离心机进泥浓度的确定、絮凝剂投加点的确定、配套液位测量仪表的选用等问题进行探讨,希望在污水处理厂在离心机的应用上取得更良好的效果。     

不同有机质污泥热水解直接脱水及厌氧消化潜力中试研究

在150～180℃条件下,利用中试实验设备,对不同来源浓缩污泥(TS约为20%)进行热水解中试实验,采用离心和板框脱水等两种方式对热水解后的污泥进行直接脱水,研究热水解温度,停留时间,污泥有机质含量等条件对污泥脱水性能的影响。选取170℃下保温60 min为最佳工况,高、中、低有机质组的污泥热水解后直接板框脱水,泥饼含固率可达到37.2%,39.8%和41.3%,同时通过对水解后的污泥,以及固液分离后的脱水液,泥饼分别进行厌氧产气实验(BMP),测定其不同热水解工况下混合相,液相,固相的产气性能,当实验开始3天后,液相甲烷产量即达到混合相最终甲烷产量的68%,72%,69%,证明了在中试条件上,热水解过程中,大部分可甲烷化有机物已转移至液相,且液相厌氧消化速度远大于固相,证明了污泥"热水解—脱水—脱水液厌氧消化"工艺路线的可行性。     

浅谈卧螺离心机在盐泥固液分离中的应用

介绍了液压差速卧螺离心机的工作机理及在盐泥浆液固液分离过程中的应用情况,实践证明在盐泥浆液脱水过程中以离心机代替板框压滤机是可行的。该项目的成功实施对纯碱盐泥脱水、盐分回收具有重要的借鉴意义。     

Optimization Study of Municipal Sludge Conditioning,Filtering, and Expressing Dewatering by Partial Least Squares Regression

The effect of different conditioner doses and different applied pressures on the dewaterability of municipal sludge during the filtration and expression stage was assessed using a series of experiments referred to as a uniform design. The relative importance of conditioner dose and applied pressure on the dewatering characteristics of municipal sludge was evaluated with a quadratic model using partial least squares (PLS) regression analysis. It was shown that the developed quadratic model was able to accurately predict the dewatering characteristics during the whole process. It was further shown that lime as a physical conditioner had the most significant impact on filtration rate, expression rate, cake dry solids content, net sludge solids yield, and total cycle time. Aluminum polychloride as the inorganic flocculant had a quite complex effect although not as significant as lime. Filtration pressure had only a slight effect on dewaterability of the municipal sludge, though higher feeding pressure was needed in order to enhance the total feeding amount. Furthermore, expression pressure was only of benefit to cake dry solids content and expression rate and failed to improve other dewatering characteristics of the municipal sludge.     

不同泥质污泥脱水性能研究

文章通过小试和中试研究了调理压榨工艺处理不同泥质的污泥时的调理效果及脱水性能的差异。结果发现,使用相同调理剂进行调理时,不同泥质的污泥脱水性能差别较大。从平均过滤速度上来看,陕西地区的污泥(S3)最慢,广东地区的污泥次之(S2),江苏地区的污泥(S1)最快。小试和中试实验中,干基处理效率排序为:S1S2S3,调整调理剂配方至三氯化铁∶生石灰=4∶7(质量比)时,能使陕西地区的污泥(S3)干基处理效率提高至于S1、S2相当的水平。中试过程中,三种污泥的中试工作周期均在3 h以内,泥饼含水率均在60%以下,满足后续填埋处置的要求。     

以颗粒煤为助滤剂对城市污泥进行二段过滤脱水的研究

以颗粒煤为助滤剂,采用二段过滤方式来强化城市污泥的脱水,并对滤饼进行热值分析,探讨城市污泥资源化利用前景.在研究中,具体分析探讨了煤的类型、煤的添加比、煤的粒径、搅拌强度、过滤压力以及煤的添加方式对过滤过程中相关参数的影响.得到以下结论:在污泥和煤的添加比为1:2,颗粒煤粒度为0.15～0.18 mm,低强度搅拌,常温...     

阴极滤布对活性污泥电渗透脱水的影响(英文)

The mechanical dewatering of activated sludge is troublesome due to its high compressibility of solids. The dewatering can be enhanced dramatically by the use of electroosmosis,in which an electric field is applied to the sludge cake.In this study,the influence of filter cloth on the cathode on the dewatering of activated sludge was investigated.It was found that thicker filter cloth led to lower water removal from the sludge cake,so a stainless steel cathode net with small pore size instead of filter cloth was applied,which improves the dewatering efficiency and reduces the electric power consumption.Moreover,water absorbent materials were helpful to remove the water from the sludge cake.For the electroosmotic dewatering at 7 kPa and 24 V·cm-1,the water content in the sludge cake decreased to 60%(by mass) with the average 0.075 kW·h·kg-1of water removed by using the cathode net.     

Tannery Waste Treatment: Leaching,Filtration and Cake Dewatering Using a Membrane Filter Press (a Pilot Plant Study)

Abstract

In Alcanena (Portugal) the waste water treatment plant (WWTP) receives tannery waste, after a pretreatment for sulphides and the tanning exhaust baths have been sent to a recovery unit and the municipal waste water from Alcanena residential area. Physical, chemical, and biological treatment processes are involved, and the end products are sludge of ～71% moisture containing mainly organic matter, sulfides, iron, chromium, and other metals. The sludge is dumped, after stabilization, in a specially designed hazardous waste landfill.

In this study, tannery mixed sludge (from chemical and biological treatments) was leached and filtered. Leaching was carried out using sulfuric acid (pH 0.5) to release residual sulfides and metals from the slurry. Hydrogen sulfide (H₂S) was flushed out into an oxidation trap (hypochlorite/alkaline tank) in which H₂S transforms to soluble sulfate. The acidified sludge was fed into a membrane filter press where it was filtered, acid‐washed, water–washed, membrane‐squeezed, and vacuum‐dried reaching lower moisture levels (20–30%). The process cycle is approximately 101–137 min in our experiments; however, from this work, a cycle of 90 min to produce cakes with 0.9 cm thickness in the industrial scale through cutting some operational time, reaching final moisture of ～20% at the end of the dewatering cycle, can be estimated. Filtration was carried out at different feed pressure (3–5 bar) with and without diatomite precoating. The effect of different amounts of diatomite body‐feed was studied. Specific cake resistance, α, was found to increase with the increase in feed pressure and to decrease with diatomite precoating and the increased amounts of diatomite body feed. Cake washing was accomplished using 0.05 M H₂SO₄ (acid washing), to remove residual metals, followed by water washing, to remove cake acidity. Cake dewatering via membrane squeezing was applied using hot water (65°C), and cake moisture was dropped from ～71% before squeezing to 42% after squeezing. With vacuum application over the hot cakes, for 30 min, cake moisture decreased to ～20% for cakes with an average thickness of 0.9 cm. Cake chemical analysis showed chromium levels lower than 1000 mg/kg (the maximum Cr concentration allowed by the Portuguese legislation in a solid residue for use in agricultural soil). In addition, produced cake (without diatomite body feed) has a calorific value of 11,000 kJ/kg and accordingly it can be used as a source of energy.     

Effect of Hydrodynamics During Crystallization on Mechanical Dewatering of Salicylic Acid

Mechanical cake dewatering is always desired to reduce the load on thermal dewatering (drying). Any change in the upstream process such as crystallization can have a significant influence on the filtration as well as cake dewatering characteristics. The present study deals with the effect of hydrodynamics (mixing intensity) during salicylic acid crystallization on the air dewatering characteristics in the subsequent pressure filtration. The mixing conditions during crystallization were varied by using three different types of agitators (anchor impeller [AI], curved blade turbine [CBT], and bar turbine [BT]) and by varying the speed of agitation. The effect of operating pressure and dewatering time on the final moisture content of the cake was also studied.

The crystal properties (crystal size and size distribution) were found to vary with the mixing intensity, which further influenced the cake dewatering kinetics as well as the residual moisture content. An AI, which is a laminar flow impeller, produced crystals with a wide size distribution and higher mean particle size, which resulted in cake with high porosity and hence higher moisture content. The high porosity (as well as high cake permeability) caused early air breakthrough, which resulted in ineffective dewatering of cake. Therefore, in this case the residual moisture in cake was found to be higher (27%) even at higher dewatering pressure (1.5 bar gauge) and longer dewatering time (90 s). A BT creates high turbulence during mixing and produced crystals with a relatively narrow size distribution and lower mean particle size, which provided low-porosity cakes. Such cakes could be efficiently dewatered and the final cake moisture content was found to decrease to about 15%, a significant improvement in the filterability of the cake. The dewatering data were modeled according to the correlation between irreducible cake saturation and capillary number for predicting the cake dewatering characteristics (residual moisture as well as dewatering kinetics) and the results were compared with the experimental data.     

Thermal Dewatering (TDW) to Reduce the Water Content of Sludge

Thermal dewatering describes the process whereby a heating plate and heat supply unit are incorporated into a filter press system to improve separation of water from sludge. The performance of our thermal dewatering system for both wastewater and waterworks sludge was measured and compared with mechanical dewatering in terms of water content, dewatering velocity, cake specific resistance, and energy consumption. Dewatering velocity was improved by a factor of two, cake water content was lower, and specific cake resistance was improved. However, energy consumption was higher. Thermal dewatering systems may be economical and have practical application to improving dewaterability.     

A study of the improvement in dewatering behavior of wastewater sludge through the addition of fly ash

Wastewater sludge is classified as a difficult dewatering material (DDM) due to the high cake specific resistance (CSR). On the other hand, fly ash is classified as an easy dewatering material (EDM), which suggests that it might be able to improve the dewaterability of wastewater sludge. The water content and cake specific resistance of dewatered sludge without the addition of fly ash were 80% and 2.9×10¹⁴ kg/m, respectively. When 50% (by dry weight) fly ash was added to the sludge, the water content and cake specific resistance decreased to 29.4% and 2.9×10¹³ kg/m, respectively. The cake specific resistance and water content decreased with increasing fly ash additions. Therefore, the production of sludge cake can be reduced by adding fly ash, which can help minimize the social and environmental problems caused by the need to dispose of wastewater sludge.     

不同絮凝剂对剩余污泥水解和脱水特性的影响

研究了无机和有机絮凝剂对剩余污泥水解和脱水性能的影响。分别投加浓度为20g/L的CaO和CPAM（阳离子型聚丙烯酰胺）调节剩余污泥,溶出的有机质规律如下：溶解性COD（SCOD）的溶出量表现为CPAM>CaO>空白;溶解性蛋白质（SPN）的溶出量表现为CPAM>CaO>空白;溶解性碳水化合物（SPS）的溶出量表现为CaO>CPAM>空白。污泥的脱水性能指标——比阻（SRF）和滤饼含固率的变化分别为：SRF表现为CPAMCaO>空白。从SPN、SPS和SCOD的溶出量、比阻和滤饼含固率的变化说明：加入CaO和CPAM都能改善剩余污泥的水解和污泥脱水性能。     

Compression Dewatering of Particulate Suspensions and Sludge: Effect of Shear

Experiments were carried out at the lab-scale to study the effect of a shearing action in a compression dewatering process. The impact of different process parameters, such as shear rate, filter-cake thickness, and pressure, on the final dry solid fraction was analyzed. Also, materials with different degrees of compressibility have been used. For slightly and moderately compressible materials (talc and kaolin, respectively), significantly higher final dry solid fractions (up to 0.79 wt/wt with talc and 0.75 wt/wt with kaolin) were obtained in the presence of a torsion shear. This behavior may mainly be explained by a rearrangement of the solid particles within the cake induced by the radial forces. A low shear rate (around 0.7 s^?1) was generally sufficient to cause a quite significant increase in the cake dryness (a 12.8% increase was observed with 11-mm-thick talc cakes). A further increase in the shear did not lead to noticeable changes in the final dry solid fraction in the cakes. Otherwise, reducing the filter-cake thickness was beneficial for the dewatering. For talc cakes, the dry solid fraction was increased by 21% for a 3 mm thickness against 7% for a 25 mm thickness. With a highly compressible material, such as activated sludge, the filter-cake dryness did not change with the application of a shearing action. This behavior may be mainly attributed to the fact that biological sludge dewatering is markedly influenced by a low permeability skin at the cake/medium interface, which is very thin and not perturbed by shear forces, due to the cake thickness. The low rigidity of the solid matter in this particular case may also limit the reorientation of the particles.