Controlling of crustacean zooplankton reproduction in biological activated carbon (BAC) filters by strengthen operation and management of conventional process

To counter the mass reproduction and penetration of crustacean zooplankton in Biological Activated Carbon(BAC)filters which may result in the presence of organisms in potable water and water pollution,this paper analyzed the factors affecting organisms' reproduction in BAC filters.A comparative study was performed on the density and composition of crustacean zooplankton of the concerned water treatment units of two advanced water plants(Plant A and B)which with the same raw water and the same treatment technique in southern China.The results obtained show that the crustaceans' density and composition was very different between the sand filtered water of Plant A and Plant B.which Harpacticoida bred sharply in the sediment tanks and penetrated sand filter into BAC filters was the primary reason of crustaceans reproduce in BAC filters of Plant A.For prevention of the organisms reproduction in BAC,some strengthen measures was taken including pre-chlorination,cleaning coagulation tanks and sediment tanks completely,increasing sludge disposal frequency to stop organisms enter BAC filters,and the finished water quality was improved and enhanced.

An Innovative Process to Improve Turbidity and Organics Removal by BAC Filters

The turbidity criterion for the product water of a WTP according to the State Project ‘863’ on the safeguard technology of drinking water in the southern areas of China is 0.1 NTU. The turbidity removal in the activated carbon filter was analyzed in a pilot-scale test and an innovative technology to improve the turbidity removal in a biologically activated carbon (BAC) filter was put forward in order to meet the criterion. Experimental results showed that the enhanced filtration by adding polymerized aluminium chloride (PAC) into the BAC filter was quite effective in turbidity control. The effluent turbidity was kept at a stable level (mean) of 0.033 NTU with a high removal of about 80% for influent turbidity of 0.110-0.240 NTU with an addition of PAC at 0.05 mg L -1, meeting the requirement for filtrate turbidity equal to or less than 0.1NTUC totally. In addition, the larger the PAC dosage was, the lower the effluent turbidity was. However, further improvement of turbidity removal was not obvious for PAC dosages beyond 0.10 mg L -1, and an optimal PAC dosage in the range of 0.]05-0.10 mg L -1 was proposed.

Unidirectional Sound Signage for Speech Frequency Range Using Multiple-Loudspeaker Reproduction System

Human safety is the most important issue in disaster management. Speech is a sound signal containing information that is easily and quickly understood by humans. Using speech as sound signage in emergency systems can effectively increase human safety in low or poor visibility conditions such as in smoke-filled situations. However, reflections of sound through walls, floor surfaces, and ceilings will affect clarity of speech. Unfortunately, because of the characteristics of sound reproduction systems, a single loudspeaker propagates sound waves omni-directionally at low frequencies. This paper proposes a simple multiple-loudspeaker system for reproducing sound with uni-directional characteristics. The proposed system consists mainly of a primary loudspeaker for introducing sound in the desired beam, a secondary loudspeaker for reducing gain in the undesired direction, and digital filters. An adaptive finite-impulse-response (FIR) filter is used to produce the controlling sound by implementing a filtered-x least-mean-square algorithm, and a delay filter for adjusting the time alignment of sound propagation between primary and secondary sources at the control point. Several operational conditions for illustrating real situations and reflections were considered in an anechoic chamber. Experimental results show the directivity patterns of the proposed multiple-loudspeaker system for the required conditions. In a low frequency range, the system is able to control unidirectional propagation;there is a sound beam in the desired direction and, conversely, reduction of gain in the undesired direction around the control point.

Estimating the instantaneous reproduction number(R_(t))by using particle filter

Background:Monitoring the transmission of coronavirus disease 2019(COVID-19)requires accurate estimation of the effective reproduction number(Rt).However,existing methods for calculating Rt may yield biased estimates if important real-world factors,such as delays in confirmation,pre-symptomatic transmissions,or imperfect data observation,are not considered.Method:To include real-world factors,we expanded the susceptible-exposed-infectiousrecovered(SEIR)model by incorporating pre-symptomatic(P)and asymptomatic(A)states,creating the SEPIAR model.By utilizing both stochastic and deterministic versions of the model,and incorporating predetermined time series of Rt,we generated simulated datasets that simulate real-world challenges in estimating Rt.We then compared the performance of our proposed particle filtering method for estimating Rt with the existing EpiEstim approach based on renewal equations.Results:The particle filtering method accurately estimated Rt even in the presence of data with delays,pre-symptomatic transmission,and imperfect observation.When evaluating via the root mean square error(RMSE)metric,the performance of the particle filtering method was better in general and was comparable to the EpiEstim approach if perfectly deconvolved infection time series were provided,and substantially better when Rt exhibited short-term fluctuations and the data was right truncated.Conclusions:The SEPIAR model,in conjunction with the particle filtering method,offers a reliable tool for predicting the transmission trend of COVID-19 and assessing the impact of intervention strategies.This approach enables enhanced monitoring of COVID-19 transmission and can inform public health policies aimed at controlling the spread of the disease.

Noise attenuation of frequency-modulated multi-rotor using sound field reproduction

Multi-rotor aircraft has great potential in urban traffic and military use and its noise problem has attracted more attention recently.Multi-rotor aircrafts are typically controlled by changing the rotation speeds of the rotors.To reduce the noise of multiple frequency-modulated rotors,a global noise attenuation method is proposed in this study.First,the fast prediction method is used to estimate the global noise of the multirotor with different configurations online.Meanwhile,the sound field reproduction method is used to obtain the control signal of the loudspeaker array to achieve global noise attenuation.Then,the influence of array arrangement on noise reduction is analyzed in the acoustic modal domain,which reveals that different optimization models are needed to minimize the noise power or/and the noise pressure in some directions when the scale of the array is limited.Next,to improve the real-time performance of the system,the online calculation of the optimal control signal is transformed into the offline design of the optimal filter,which satisfies the target frequency-domain characteristics.Finally,the experimental results of the noise of a model quadrotor in the anechoic chamber were consistent with the predicted results.The simulation results of noise attenuation for the quadrotor show that the method proposed reduced the global noise power by about 13 dB.Moreover,the noise region radiated from the quadrotor to the ground with the boundary of 40 dB was reduced to 8.4%of that before control.

针对O_3—BAC工艺生物泄露问题后置砂滤池级配研究

利用砂滤池的截滤作用,对给水深度处理工艺炭滤池出水微型生物进行把关,解决O3-BAC工艺生物穿透问题。结果表明,后置砂滤池比常规净水工艺砂滤池出水微型生物密度小,后置砂滤池采用粒径较小的滤砂能更好地解决微型生物穿透现象。对于浊度为0.5 NTU左右的炭滤池出水,应适当采用粒径较小的滤砂,以提高对浊度的去除率,采用双层填料砂滤池可以使出水平均浊度降至0.10 NTU,提高了城市供水生物安全性。

上向流BAC吸附池在净水生产中的应用

嘉兴贯泾港水厂一期规模15万m3/d,采用生物预处理+加强常规+O3—BAC深度处理工艺。为了降低BAC吸附池出水微生物泄漏风险,引入了上向流BAC吸附池结合后续砂滤池的新型组合工艺。介绍了上向流BAC吸附池的应用情况和特点,总结了该工艺对活性炭选型的强度和粒径等要求,并指出在运行中应注意进水浊度和上升流速控制等问题。嘉兴贯泾港水厂砂滤出水、出厂水浊度均≤0.1 NTU,砂滤出水中≥2μm的颗粒数≤30个/mL,有效保障了城市供水水质安全。

利用杆状病毒Bac-to-Bac系统在家蚕表达猪繁殖与呼吸综合征病毒的E蛋白和M蛋白

猪繁殖与呼吸综合征病毒(PRRSV)是一种严重危害养猪业的传染性病原。PRRSV病毒的E蛋白和M蛋白基因是开发PRRSV病毒新型疫苗的目标基因。利用杆状病毒Bac-to-Bac表达系统,将PRRSV病毒的E蛋白和M蛋白的基因亚克隆到杆状病毒转移载体pFastBacHTb中,获得重组转移质粒pFastBacHTb-E和pFastBacHTb-M,转化大肠杆菌Bm DH10 Bac感受态细胞,获得重组杆粒BmNPV Bacmid-E、BmNPV Bacmid-M,将这些重组杆粒转染家蚕培养细胞Bm5,获得重组病毒BmNPV-E和BmNPV-M。将2种重组病毒分别接种5龄起蚕,用SDS-PAGE和Western blotting方法在重组Bacmid DNA转染的Bm5细胞和感染重组病毒的家蚕幼虫血细胞中分别检测到分子质量约20 kD和18 kD的E蛋白和M蛋白,表明PRRSV病毒的E蛋白和M蛋白在家蚕培养细胞及幼虫体内获得了表达,为利用家蚕-杆状病毒表达系统研制PRRSV的新型疫苗与诊断试剂奠定了基础。

环境因子对BAC滤池中无脊椎动物生长的影响研究

于2006年10月—2007年9月,在南方某地区采用相同水源的两座水厂内研究了进水无脊椎动物密度、水温、反冲洗、活性炭类型等4种因子对生物活性炭滤池中无脊椎动物生长的影响。结果表明,进水中无脊椎动物的密度越高,则滤池上层水中无脊椎动物的生长繁殖数量越大,且微生物出现泄漏的可能性就越高;进水水温越高,则越有利于无脊椎动物的快速繁殖;反冲洗对滤池中无脊椎动物具有较好的去除作用,能够显著降低滤后水的微生物密度;活性炭类型对无脊椎动物的生长也具有重要影响,柱状炭滤池比破碎炭滤池易滋生更多的无脊椎动物,这对生物活性炭滤池中无脊椎动物的控制技术有着非常重要的意义。

O_3—BAC工艺处理微污染地表水的试验研究

采用预臭氧—曝气生物活性炭滤池(O_3—BAC)工艺处理低碳源的北运河通州段原水,探讨了该系统的主要工艺参数与各项污染物去除效果的相关性。研究结果表明,臭氧的投加对提高COD_(Cr)和NH_3—N的去除效果均有促进作用,且在投加量3 mg/L、接触时间30 min时臭氧利用效率最高;在此投加量和接触时间、回流比1:1时,COD_(Cr)和NH_3—N的去除率分别可达42%和94.3%,均高于回流比为0.5:1时,而TN去除率为13.4%,有所降低,投加外碳源和降低好氧单元气水比可使之升高;系统对UV_(254)去除率达到38.8%,其中臭氧接触单元去除率为18.66%,由臭氧氧化特性推断,原水中大分子有机物以芳香族化合物为主。

上海N水厂不停产深度处理改造及调试实施

上海N水厂深度处理改造工程设计规模为44万m^(3)/d,采用O3-BAC深度处理工艺,根据工艺特性,结合工程建设及水厂运行情况,实施不停产深度处理工程改造。在深度处理改造工程施工及调试阶段,有效解决了对上海N水厂原出水管保护、新老管线碰接等工程难点,并统筹制定了单机调试、联动调试和满负荷调试方案。在实施过程中,通过加强对构筑物及管道的冲洗、投加CO_(2)调控炭滤池反冲洗水p H等措施,保证了深度处理改造工程与现有生产系统的顺利衔接,并解决了排空阀降噪的问题,经调试后出厂水各项指标全面达到《生活饮用水卫生标准》(GB 5749—2022)和该地区地方水质标准要求。

Effect of a biological activated carbon filter on particle counts

Due to the importance of biological safety in drinking water quality and the disadvantages which exist in traditional methods of detecting typical microorganisms such as Cryptosporidium and Giardia, it is necessary to develop an alternative. Particle counts is a qualitative measurement of the amount of dissolved solids in water. The removal rate of particle counts was previously used as an indicator of the effectiveness of a biological activated carbon (BAC) filter in removing Cryptosporidium and Giardia. The particle counts in a BAC filter effluent over one operational period and the effects of BAC filter construction and operational parameters were investigated with a 10 m3/h pilot plant. The results indicated that the maximum particle count in backwash remnant water was as high as 1296 count/ml and it needed about 1.5 h to reduce from the maximum to less than 50 count/ml. During the standard filtration period, particle counts stay constant at less than 50 count/ml for 5 d except when influ- enced by sand filter backwash remnant water. The removal rates of particle counts in the BAC filter are related to characteristics of the carbon. For example, a columned carbon and a sand bed removed 33.3% and 8.5% of particles, respectively, while the particle counts in effluent from a cracked BAC filter was higher than that of the influent. There is no significant difference among particle removal rates with different filtration rates. High post-ozone dosage (>2 mg/L) plays an important role in particle count removal; when the dosage was 3 mg/L, the removal rates by carbon layers and sand beds decreased by 17.5% and increased by 9.5%, respectively, compared with a 2 mg/L dosage.

曝气生物滤池在高标准污水处理厂提标改造中的应用

江苏某市由于区域污染物排放总量的限制,当污水排放量增长后需降低污染物的排放浓度,该市某污水厂因此要进行提标改造,建设规模为1.7×10^(5)m^(3)/d,出水水质由一级A提高至地表“类Ⅲ类水标准”。文中总结了该污水厂提标的设计经验,设计采用“硝化+反硝化+滤布过滤+臭氧-生物活性炭(O_(3)-BAC)+超滤”处理工艺,脱氮处理构筑物采用曝气生物滤池,抗冲击负荷强,运行管理简单,滤池平均36~48 h反冲洗一次,硝化滤池各级出水设置导流板后,反硝化滤池进水溶解氧质量浓度可稳定在4~6 mg/L。单位用地面积为0.15 m^(2)/(m^(3)·d^(-1))。根据2020年—2021年的运行数据,当进水COD_(Cr)、BOD5、SS、氨氮、TN、TP质量浓度为12~26、3.8~7.1、1~6、0.22~2.22、5.34~11.60、0.15~0.40 mg/L时,各污染物平均去除率分别为29%、23%、44%、57%、52%、68%,通过该工艺处理后出水水质稳定达标,为未来污水厂更严格的排放标准提供了升级提标工艺思路和经验借鉴。

生物活性炭吸附池无脊椎动物群落变化及对水质影响

在中试模拟炭柱上对生物活性炭吸附池无脊椎动物的孳生繁殖以及群落变化规律进行了为期1年的研究。研究结果表明,活性炭吸附柱中孳生的无脊椎动物包括轮虫、桡足类、枝角类、寡毛类和线虫等,轮虫是占绝对优势的类群,这些无脊椎动物进入饮用水中将对饮用水水质产生不良影响。随着运行时间的延长,无脊椎动物总密度呈接近指数上升的趋势,在150d左右达到最大值,250d左右出现第二个峰值。水温对无脊椎动物生长有显著影响,最适宜的生长温度是28℃左右。不同无脊椎动物群落密度出现峰值的顺序依次为:枝角类、轮虫、桡足类、寡毛类(和线虫)。

有机紫外防晒剂内分泌干扰效应研究进展

有机紫外防晒剂是一类新兴环境污染物,大量研究表明,部分有机紫外防晒剂能模拟生物体内多种激素的作用,干扰动物和人体正常的内分泌功能,造成严重的健康威胁.本文在大量文献调研的基础上,从个体水平、器官水平、细胞水平和分子水平4个层次,就有机紫外防晒剂对生殖系统、青春期发育、成活率、pS2蛋白、卵黄蛋白原及激素受体等多方面的影响进行了综述,以加深对紫外防晒剂的认识,也为紫外防晒剂的正确使用及相关部门对其进行科学管理提供参考.

净水厂滤池反冲洗水回用的贾第鞭毛虫和隐孢子虫的泄漏问题研究

采用美国EPA1623方法,研究滤池反冲洗水回用的贾第鞭毛虫和隐孢子虫泄漏问题。通过检测某水厂原水、出厂水和滤池反冲洗水中贾第鞭毛虫和隐孢子虫数量,表明该厂水源未受到贾第鞭毛虫和隐孢子虫的污染,但输送过程易造成水质的污染。滤池反冲洗水中只检出贾第鞭毛虫,出厂水中未检出贾第鞭毛虫和隐孢子虫,说明该厂滤池反冲洗水直接回用未造成“两虫”泄漏问题。

臭氧+生物滤池组合工艺深度处理酿酒废水应用研究

采用O3＋BAC生物滤池组合工艺对酿酒废水生化处理出水进行深度处理实验研究。结果表明,O3氧化投加量为20~30 mg/L,可满足脱色要求;O3单位投加量超过80 mg/L时,可满足出水COD要求;O3＋H2O2高级氧化工艺相比O3直接氧化可节约O3投加量约30 mg/L;对氧化出水进行BAC生物滤池处理,可进一步去除COD约28%左右。“O3＋H2O2/BAC”组合工艺发挥了化学氧化和生物降解的协同降解效果,在酿酒废水深度处理中具有较强的经济性和工程应用价值。

生物活性炭滤池在给水深度处理中的应用

以臭氧-活性炭给水深度处理工艺中试试验为基础,研究活性炭滤池对微污染水的处理效果。实验结果表明:活性炭滤池出水高锰酸盐指数平均值为1.077mg/L,对砂滤池出水高锰酸盐指数的去除率为40.00%;氨氮平均值为0.037mg/L,去除率为94.57%;亚硝酸盐氮平均值为0.003mg/L,去除率为97.39%;浊度平均值为0.438NTU,去除率为13.61%。由此可见,活性炭滤池在此工艺中发挥着很重要的作用。

双层填料中置生物活性炭滤池中试优化研究

采用中置生物活性炭滤池,装填双层填料,对进水浊度约1 NTU左右的沉淀池出水进行去除浊度和有机物中试。结果表明,装填厚3 m粒径准3 mm柱状炭、垫层分别采用厚0.7 m粒径准3～5 mm与厚1.2 m粒径准6～8 mm轻质陶粒,于12 m.h-1滤速、气水体积比为0.2:1的工况下运行时,平均水压损失分别为3.41 kPa和2.81 kPa,CODMn平均去除率分别为41.5%和46.3%;后者在16 m.h-1滤速,气水体积比0.2:1的工况下运行时,平均水压损失为4.08kPa,CODMn平均去除率为41.4%。

参数控制的混合色调映射方法

为解决高动态图像的真实影像再现问题,提出了一种基于参数控制的混合色调映射方法.对图像进行全局预处理,保持整幅图像的亮度和对比度;采用参数控制的混合算子获取图像的局部对比度和细节;采用双边滤波解决色调映射过程中产生的光晕问题.仿真实验表明,该方法压缩了原始高动态图像的动态范围,保持了整体亮度,增强了局部细节而去除光晕效应影响,比现有的Sigmoid算法在各个参数上有显著提高.