输配水系统中颗粒物与浊度演变特征研究

通过将颗粒物计数方法应用于城市输配水系统,研究分析了输配水系统中颗粒物数量与浊度的相关性以及其沿线变化规律.结果表明,随着水流方向,颗粒物数量有上升趋势;管网末梢颗粒物数量和浊度偏高;颗粒粒径越小,其含量越多;在一定范围内颗粒物数量和浊度有一定相关性;对颗粒物的研究比浊度更加准确和直观.此外,从颗粒物角度对水质进行特征分析,不仅为水质评价提供更多信息,还为颗粒物计数法的应用提供基础数据.     

Inactivation of indigenous coliform bacteria in unfiltered surface water by ultraviolet light

This study examined the potential for naturally occurring particles to protect indigenous coliform from ultraviolet (UV) disinfection in four surface waters. Tailing in the UV dose-response curve of the bacteria was observed in 3 of the 4 water samples after 1.3-2.6-log of log-linear inactivation, implying particle-related protection. The impact of particles was confirmed by comparing coliform UV inactivation data for parallel filtered (11 microm pore-size nylon filters) and unfiltered surface water. In samples from the Grand River (UVT: 65%/cm; 5.4 nephelometric turbidity units (NTU)) and the Rideau Canal (UVT: 60%/cm; 0.84 NTU), a limit of approximately 2.5 log inactivation was achieved in the unfiltered samples for a UV dose of 20 mJ/cm2 while both the filtered samples exhibited >3.4-log inactivation of indigenous coliform bacteria. The results suggest that particles as small as 11 microm, naturally found in surface water with low turbidity (<3NTU), are able to harbor indigenous coliform bacteria and offer protection from low-pressure UV light.     

A novel method for on-line evaluation of floc size in coagulation process

Chemical coagulation is a simple and widely used water treatment process. A jar test based on the residual turbidity in the treated water was used to evaluate the optimal conditions for floc formation. However, the final residual turbidity does not show up variation of turbidity and floc formation during the flocculation process. Hence, a nephelometric turbidimeter method based on on-line monitoring was devised to determine the floc size variance during flocculation. A nephelometric turbidimeter coupled with a data acquisition unit was used to measure turbidity every second at 3 cm below the water surface during the coagulation process. Laboratory results indicated that this new instrument was capable of recording floc agglomeration during slow mixing very accurately. The standard deviation (SD) of the measured turbidity was proportional to the square root of the floc size; a greater SD indicated larger floc sizes. Hence, in addition to monitoring turbidity, the nephelometric turbidity meter is also a valuable tool to study the floc agglomeration process and variations in the resulting floc size. This method is simple and effective; it contributes significantly to the selection of coagulant and optimal flocculation conditions to improve water treatment.     

Removal of virus to protozoan sized particles in point-of-use ceramic water filters

The particle removal performance of point-of-use ceramic water filters (CWFs) was characterized in the size range of 0.02-100 μm using carboxylate-coated polystyrene fluorescent microspheres, natural particles and clay. Particles were spiked into dechlorinated tap water, and three successive water batches treated in each of six different CWFs. Particle removal generally increased with increasing size. The removal of virus-sized 0.02 and 0.1 μm spheres were highly variable between the six filters, ranging from 63 to 99.6%. For the 0.5 μm spheres removal was less variable and in the range of 95.1-99.6%, while for the 1, 2, 4.5, and 10 μm spheres removal was >99.6%. Recoating four of the CWFs with colloidal silver solution improved removal of the 0.02 μm spheres, but had no significant effects on the other particle sizes. Log removals of 1.8-3.2 were found for natural turbidity and spiked kaolin clay particles; however, particles as large as 95 μm were detected in filtered water.     

BAC滤池对浊度和颗粒数的控制研究

传统的贾第鞭毛虫和隐孢子虫（简称“两虫”）检测方法存在诸多不足，为此选用浊度和颗粒数作为“两虫”的替代指标，以对浊度和颗粒物的去除率来衡量生物活性炭（BAC）滤池对“两虫”的控制效果。试验结果表明：采用颗粒数表征滤后水水质比采用浊度更适宜。过滤初期颗粒数从峰值降到50个／mL以下所需的时间比浊度降到0．1NTU所需的时间多1h左右。正常过滤期间BAC滤池进水浊度一般在0．1NTU以下，经过BAC滤池处理后，浊度得到进一步降低，平均去除率为52．7％。炭层对浊度的去除率为56．4％，其出水浊度基本上都低于0．05NTU，而砂层对浊度不但没有去除能力，反而使出水浊度平均上升了约3．7％。炭层对颗粒物的平均去除率为33．3％，砂层对颗粒物的平均去除率为8．5％。     

Particle size distribution dynamics during precipitative softening: declining solution composition

Particle removal is a critical step in the treatment of surface water for potable use, and the majority of drinking water treatment plants employ precipitative coagulation processes such as alum and iron “sweep-floc” coagulation or lime softening for particle pre-treatment. Unfortunately, little is quantitatively known about how particle size distributions are shaped by simultaneous precipitation and flocculation. In an earlier paper, we demonstrated the effects of the saturation ratio, the mixing intensity and the seed concentration on the rates of homogeneous nucleation, precipitative growth and flocculation during precipitation of calcium carbonate at constant solution composition using electronic particle counting techniques. In this work, we extend those findings to systems more closely emulating the conditions in actual softening processes (i.e., declining solution composition). Key findings include the strong dependence of the rate of flocculation on the initial saturation ratio and demonstration of the benefits of seeding precipitative softening from the perspective of optimizing the effluent particle size distribution. The mixing intensity during precipitation was also shown to strongly influence the final particle size distribution. Implications of the findings with respect to softening practice are discussed.     

浊度计法测定水样浊度的探讨

采用浊度计法测定水样的浊度,结果表明：相对标准偏差（RSD）为0.18%~5.40%,方法的加标回收率为95.6%~105.5%,具有灵敏度高、准确度好、精密度好、仪器操作方便等优点,适合低、中、高浊度水样的测定,是水中浊度测定的较好的方法。     

Comparing in situ particle monitoring to microscopic counts of plankton in a drinking water reservoir

In a one-year study, the multispecies assemblages of phytoplankton (picoplankton to microplankton) within a drinking water reservoir were counted, determined and evaluated in their size fractions using microscope enumeration (MC). The manual counts were compared with the size evaluation obtained by a light obscuring particle counter (PC) in order to evaluate its use for the monitoring practice of a drinking water reservoir. With this multispecies comparison we present a novel approach for the evaluation of automated counting systems.The picoplankton clearly remained uncounted by the PC even though its lower size limits imply an adequate match. The highest and most consistent count numbers of plankton (nano- and microplankton) and particles were obtained during the spring mass development. However, from the middle of the year onwards, the measured particle concentration surpassed the counted plankton abundances by two- to threefold indicating the rise of seston within the water column. This fraction would be missed if counted solely by MC. Further, the PC consistently undersized the biological counts, but not the minerogenic fraction represented by the manganese oxidising bacteria. Consequently, the rise and decline of Metallogenium bacteria was reliably monitored with the PC.The PC provides additional size information compared to other bulk optical sensors (turbidity, chlorophyll-a). The correlation of particles with probe measurement always exceeded the plankton coefficient, but all combinations of plankton, particle and probe measurement revealed significant linear regressions. However, the redundancy of the chlorophyll-a probes was also shown in order to explain plankton abundances.Our results indicate that background knowledge of the monitored system and cautious interpretation of data is required to allocate and understand automated particle counts. Therefore, only in combination with MC, the PC enables phytoplankton or minerogenic particle counts under frequent real-time monitoring conditions. As such it may serve as a helpful tool for example in critical situations in the management of drinking water reservoirs.     

细砂滤料的过滤性能及运行效果

基于提升滤后水水质对石英砂粒径的选用问题,通过中试研究了两种不同粒径分布的石英砂过滤性能,探讨细砂滤料使用的可行性。研究结果表明,细砂的滤后水浊度更低,能解决高浊度的突发性水质问题;细砂对无脊椎动物的截留效果显著,并能有效应对轮虫等小尺寸生物风险;细砂滤料保持并提升了滤池对有机物和氨氮的去除能力;细砂的水头损失增长更快,降低进水浊度能有效延长其运行时间;对比于其他深度处理工艺,细砂滤料拥有部分膜处理功能,无需增加净水厂用地。     

The evaluation of colour in natural waters

A model describing the objective evaluation of colour from the transmission properties of natural waters was developed and applied to a wide range of Australian waters. These calculated colours show that measurement of filtered water absorbance at 456 nm calibrated against Pt-Co colour standards agrees with the visually perceived colour intensity by comparator methods and the Pt-Co or Hazen scale of measurement within a maximum error range of ±20%. The error is significantly larger when analytical wavelengths below 440 nm are used. The interference to colour measurement caused by scattering of suspended matter was accounted for at the analytical wavelength. The light scatter component was found to be significant when the ratio of turbidity (in nephelometric turbidity units) to colour (in Hazen units) is greater than 0.02. The use of the 456 nm wavelength is proposed for the standardization of colour measurement in natural waters.     

Particle size distribution dynamics during precipitative softening: constant solution composition

In the treatment of surface water for potable use, precipitative coagulation (e.g., lime softening, alum or iron sweep coagulation) is widely utilized prior to particle removal processes. The particle size distribution (PSD) formed during such processes is a prime determinant of the removal efficiency for suspended and dissolved contaminants, but little is known quantitatively about how PSDs change by simultaneous precipitation and flocculation. Using precipitative softening as an example, detailed measurements of the PSD (using electronic particle counting) were made during precipitation of CaCO(3) under conditions of constant solution composition. Examination of the time-varying PSDs revealed dramatic changes resulting from nucleation, crystal growth, and flocculation. The influence of the saturation ratio, seed concentration, and mixing intensity on those processes was quantified. Implications with respect to the design and operation of water treatment facilities are discussed.     

典型低温低浊水体的混凝工艺条件研究

以新疆额尔齐斯低温低浊河水为典型研究对象，通过调节絮凝反应条件和增加颗粒物浓度，并结合颗粒计数、絮体成长监测、过滤性能评价等方法，对低温低浊水的混凝工艺条件进行了研究。结果表明：絮凝慢速反应时间为20～25min，水力剪切强度G=30s^-1，其对应的GT值为（3．6～4．5）×10^4时，可以得到较好的混凝效果。此外，通过投加高岭土提高原水浊度，沉后水的过滤性能得到显著改善。     

Impact of particles on sediment accumulation in a drinking water distribution system

Discolouration of drinking water is one of the main reasons customers complain to their water company. Though corrosion of cast iron is often seen as the main source for this problem, the particles originating from the treatment plant play an important and potentially dominant role in the generation of a discolouration risk in drinking water distribution systems. To investigate this thesis a study was performed in a drinking water distribution system. In two similar isolated network areas the effect of particles on discolouration risk was studied with particle counting, the Resuspension Potential Method (RPM) and assessment of the total accumulated sediment. In the ‘Control Area’, supplied with normal drinking water, the discolouration risk was regenerated within 1.5 year. In the ‘Research Area’, supplied with particle-free water, this will take 10-15 years. An obvious remedy for controlling the discolouration risk is to improve the treatment with respect to the short peaks that are caused by particle breakthrough.     

飞机货舱典型可燃物燃烧火灾特征参数试验研究

摘 要：光电式火灾烟雾探测器是目前民用飞机货舱使用的主流火灾探测器,是保障飞机安全运行的关键,该探测器是基于烟雾颗粒对光的散射信号来进行报警的,但是由于空气中悬浮颗粒物（水蒸气或灰尘等）也具有散射效应,同样会触发火灾探测器发生报警,这种原理上的缺陷造成的误报情况时有发生。通过对飞机货舱典型燃烧物瓦楞纸片、榉木和棉绳的蓝光散射功率（表征为表面积浓度）、红外光散射功率（表征为体积浓度）和颗粒物索特平均粒径火灾特征参数进行分析,为复合探测器的研发优化火灾特征参数。结果表明：在常压条件下,蓝光和红外光对颗粒物浓度的变化有很好的响应,索特平均粒径可以区分火灾烟雾颗粒和非火灾烟雾颗粒,可以有效降低误报率。     

中桥水厂超滤膜深度处理工艺中试研究

分别以滤后水和沉后水作为进水,考察了超滤膜深度处理工艺的净水效能、膜通量、渗透性及清洗方式.结果表明,超滤膜深度处理工艺对浊度、总铁及色度具有较好的去除效果;以滤后水和沉后水作为超滤膜进水时,适宜的膜通量范围分别为(70 ～80)和(50～60) L/(m2·h);超滤膜-粉末活性炭组合工艺对浊度的去除效果很好,当PAC投加量为15 mg/L时,浊度去除率大于80.7％,TOC、CODMn 、UV254及氨氮去除率基本小于30％.     

饮用水钙硬度去除中C/Ca值对CaCO3结晶的影响

饮用水中钙硬度去除效能主要受CaCO3结晶过程影响。通过改变C/Ca值模拟饮用水钙硬度去除,考察不同C/Ca值条件下,溶液体系pH值和Ca^2+浓度变化、上清液浊度变化以及结晶产物颗粒粒径分布、晶型和形态,以阐明钙硬度去除过程中CaCO3结晶行为。结果表明:试验条件下结晶产物均为方解石;溶液体系中加入的CO3^2-首先发生质子化,提高体系pH值,然后与Ca^2+结晶反应降低体系pH值;C/Ca值的增大提高了pH值,有助于Ca^2+的去除,但同时也会提高结晶产物颗粒数量、密度和减小结晶产物颗粒粒径,导致上清液浊度增大。饮用水钙硬度去除中要综合考虑残余Ca^2+浓度、出水pH值和浊度以及混凝剂用量等来优化确定C/Ca值。     

三种深度处理工艺出水的微生物安全性比较

分别从浊度、颗粒数、细菌总数、HPC和浮游动物等方面进行研究,探讨了炭砂倒置工艺、炭砂滤池以及炭砂滤池/超滤复合工艺等三种给水深度处理技术对微生物安全性的保障作用。结果表明,炭砂滤池/超滤复合工艺对微生物的安全保障能力大大高于其他两种工艺。炭砂滤池/超滤复合工艺的出水水质非常稳定,浊度一般为0.01～0.03 NTU左右,平均为0.022 NTU,粒径2μm的颗粒数10个/mL;而其他两种工艺的出水浊度一般在0.1 NTU左右,颗粒数一般为几十至几百个/mL,且水质波动较大。炭砂过滤和炭砂倒置等两工艺出水的细菌总数和HPC均较高,存在一定的微生物风险;炭砂倒置工艺中的砂滤对降低微生物数量起到重要作用;复合工艺出水的细菌总数和HPC均很低。浮游动物能穿透炭砂滤层而出现在出水中;炭砂倒置工艺出水中的浮游动物数量有较大下降;复合工艺对浮游动物的截留效果非常好,出水中几乎不含浮游动物,只是偶尔检出数个轮虫。     

Low-pressure membrane integrity tests for drinking water treatment: A review

Low-pressure membrane systems, including microfiltration (MF) and ultrafiltration (UF) membranes, are being increasingly used in drinking water treatments due to their high level of pathogen removal. However, the pathogen will pass through the membrane and contaminate the product if the membrane integrity is compromised. Therefore, an effective on-line integrity monitoring method for MF and UF membrane systems is essential to guarantee the regulatory requirements for pathogen removal. A lot of works on low-pressure membrane integrity tests have been conducted by many researchers. This paper provides a literature review about different low-pressure membrane integrity monitoring methods for the drinking water treatment, including direct methods (pressure-based tests, acoustic sensor test, liquid porosimetry, etc.) and indirect methods (particle counting, particle monitoring, turbidity monitoring, surrogate challenge tests). Additionally, some information about the operation of membrane integrity tests is presented here. It can be realized from this review that it remains urgent to develop an alternative on-line detection technique for a quick, accurate, simple, continuous and relatively inexpensive evaluation of low-pressure membrane integrity. To better satisfy regulatory requirements for drinking water treatments, the characteristic of this ideal membrane integrity test is proposed at the end of this paper.     

Testing and modelling total suction effects on compressibility and creep of crushable granular material

Recent works have shown that delayed events of particle crushing are partially responsible of creep deformation in granular materials, and that Stress Corrosion Cracking promoted by high humidity within particles is the source of this mechanism. A number of experimental studies have focused on creep behaviour of water saturated samples and wetting-deformation after soaking dry material. However, there are few evidences of the effect of varying total suction in time-dependent deformation of partially saturated crushable material, and this mechanism have been rarely considered in constitutive models. The aims of this paper are to present experimental evidence of the effect of total suction on compressibility and creep of sandy sized samples from crushed rock, and to propose a simple one-dimensional elasto-plastic modelling approach based on the enhancement of an existing model. Oedometric compression tests at different total suctions are presented. The results show that compressibility and creep strains increase with both stress and humidity. The model proposed uses a time-dependent hardening law coupling suction with the amount of particle breakage. Based on preliminary calibrations, the model captures the effect of suction and time-dependent behaviour over a large range of total suction.     

Wastewater quality monitoring system using sensor fusion and machine learning techniques

A multi-sensor water quality monitoring system incorporating an UV/Vis spectrometer and a turbidimeter was used to monitor the Chemical Oxygen Demand (COD), Total Suspended Solids (TSS) and Oil & Grease (O&G) concentrations of the effluents from the Chinese restaurant on campus and an electrocoagulation-electroflotation (EC-EF) pilot plant. In order to handle the noise and information unbalance in the fused UV/Vis spectra and turbidity measurements during the calibration model building, an improved boosting method, Boosting-Iterative Predictor Weighting-Partial Least Squares (Boosting-IPW-PLS), was developed in the present study. The Boosting-IPW-PLS method incorporates IPW into boosting scheme to suppress the quality-irrelevant variables by assigning small weights, and builds up the models for the wastewater quality predictions based on the weighted variables. The monitoring system was tested in the field with satisfactory results, underlying the potential of this technique for the online monitoring of water quality.