The dissolution of total suspended solids and treatment strategy of tailwater in a Litopenaeus vannamei recirculating aquaculture system

In recirculating aquaculture systems(RASs),the effective treatment of aquaculture tailwater is essential to maintain the health of the RAS.This study investigated the optimal time and method for tailwater treatment during three periods of the aquaculture of the Litopenaeus vannamei:nursery(0–26 d),middle(27–57 d),and later(57–104 d).The variation of several water parameters during the dissolution of total suspended solid(TSS)in tailwater,applied with the effects of ozone on the microorganism and water quality parameters were investigated.Results showed that the TSS concentrations in tailwater decreased with time,although not significantly(P>0.05),whereas total ammonia nitrogen(TAN),nitrite(NO-2-N),and nitrate(NO_(3)^(-)-N)increased significantly(P<0.05).Therefore,TSS should be removed from the tailwater as early as possible,being most optimal within 4 h.Ozone removed 38.24%–48.95%of TSS,17.78%–90.14%of TAN,and 87.50%–98.90%of NO-2-N after 4 h of treatment.However,it resulted in the significant accumulation of NO_(3)^(-)-N.Moreover,the total number of Vibrio and bacterial counts in aquaculture tailwater was reduced completely by ozone within 4 h.Thus,these results provided technical details and data support for the effective treatment of tailwater from shrimp RAS.

Heavy-metal contents in suspended solids of Meiliang Bay,Taihu Lake and its environmental significances

Surface water was taken from river mouth to the central area of Meiliang Bay, Taihu Lake, a large shallow eutrophic lake in China. Suspended solids were condensed by centrifugation 25 L surface water samples from each selected site. Suspended solids and surface sediments were further freeze-dried and microwave digested before determining the metals by ICP-AES. Among the metals analyzed in suspended solids and sediments, contents of Cr, Cu, Mn, Ni, and Zn in suspended solids were significantly higher than those in sediments while contents of Al, Ba, Be, Ca, Co, Fe, K, Mg, Pb, and V in suspended solids were 10%—30% higher than those in sediments. Sr and Ti contents in suspended solids and sediments were very similar. Na content in suspended solids was lower than that in sediments. Heavy metals were significantly accumulated in suspended solids. From the river mouth to the center of Meiliang Bay, contents of Cr, Cu, Pb, and Zn in suspended solids showed a gradual decreasing trend indicating the river(Zhihugang River) still discharged large quantity of heavy metals to Meiliang Bay. The study suggests that the geochemical behaviors and ecological effects of heavy metals in suspended solids may serve as a good indicator for the pollution of lake.

Growth properties of mixed liquor suspended solids in SMBR for pharmaceutical wastewater treatment

This paper presents the performance results of a 366-day pilot-scale submerged membrane bioreactor (SMBR) for treating high-strength pharmaceutical wastewater. The study focuses on the growth properties of mixed liquor suspended solids (MLSS) in SMBR operated at high volumetric loading rates. The influences of MLSS on COD removal,sludge yield,oxygen utilization rates and sludge viscosity are studied. Results show that the bioreactor can be operated at higher volumetric loading rate with a low sludge yield. VSS/SS and observed sludge yield coefficient (Yo) present a decreasing trend with the decrease of hydraulic retention time (HRT) . Sludge oxygen utilization rate decreases with the increase of mixed liquor volatile suspended solids (MLVSS) . A mathematical model between sludge viscosity and MLSS is developed.

RESEARCH ON STABILITY OF MOVING JET CONTAINING DENSE SUSPENDED SOLID PARTICLES

The spatial stability equation of moving jet containing dense suspended solid particles was derived out by means of the continuum phase-coupled model. The stability curves of moving jet far different downstream distances, Reynolds number of flow-field, particle properties and velocities of jetting device are got by the finite difference method based on the asymptotic method and the Eulerian conservative difference scheme. Founded on the analysis of the obtained stability curves it is found that the positive velocity of jetting device widens the unstable frequency range of flow-field hut the effect of the negative one is contrary. In addition, particles existing in the flow-field curb the instability of flow-field and the effect enhances with the decrease of Reynolds number of flow-field. These conclusions benefit learning the development of moving two-phase jet.

Characterization of suspended solids and particle-bound heavy metals in a first flush of highway runoff

To investigate the dynamic characteristics of total suspended solids (TSS) and their particle-bound heavy metals in a first flush, the runoff sampling together with its flow rate measuring was conducted for three rainfall events at outfalls of highway in Shanghai from June to September 2007. Field samples were analyzed to determine the concentrations of TSS and particle-bound heavy metals, such as Zn, Pb, and Cu. Results show that the wash off behavior of TSS under varying runoff rate condition can be explained by different antecedent dry weather period (ADWP). Contribution of fine fraction (<45 μm) to TSS was generally higher than that of coarse fraction (>45 μm). When the runoff flow increased obviously, a significant contribution of the coarse fraction was observed for a certain rainfall events with long antecedent dry weather condition. The changes of total metals concentration and particle-bound metal concentrations were strongly dependent on the TSS variation. TSS was generally well correlated with most particulate-bound heavy metals. Of the heavy metals, the concentration of Zn was found considerably high and that of Pb was significantly low at North Zhongshan 2 Road, in Shanghai, China, but they are still within the range reported in the literature. Fluctuation of heavy metal contents in the coarse fraction during a first flush period was more significant compared with that in the fine fraction. The results will assist in the development of effective control strategies to minimize heavy metals and solids in highway runoff.

Retrieval of chlorophyll a and suspended solid concen-trations by hyperspectral remote sensing in Taihu Lake,China

Chlorophyll a (chl-a) and suspended solid concentrations are two frequently used water quality parameters for monitoring a lake. Traditional measurement of chl-a and suspended solids, requir-ing laborious laboratory work, which is often expensive and time consuming. Hyperspectral re-mote-sensing measurement provides a fast and easy tool for estimating water trophic status. In situ hy-perspectral data on March 7–8, July 6–7, September 20 and December 7–8, 2004 and the corresponding water chemical data were used to regress the algorithm of water quality parameters. Results showed that the peak of water leaving radiance around 700 nm (R700) varied proportionally with chl-a concentration, and moved to infrared when algal bloom occurred. The reflectance ratio of R702/R685 was well correlated with chl-a when water surface in no algal bloom case and the correlation coefficient was better if absorp-tion of phycocyanin was considered. The reflectance ratio R620/R531 was highly correlated to the concen-tration of suspended solids. The relationship between suspended solids and other band groups were also compared. Secchi disk depth could be calculated by non-linear correlation with suspended solids concen-tration.

Modeling transportation of suspended solids in Zhujiang River estuary, South China

A three-dimensional transportation model for suspended solids (SS) in Zhujiang (Pearl) River estuary, South China, was developed by coupling with a three-dimensional hydrodynamic model. The model was validated using hourly measured data of sediment contents during 25–26, July 1999. The results showed that modeled contents matched well with measured ones and that the modeled top layer distribution agreed with the remotely sensed image of suspended solids in summer. The modeled results showed clearly the layers of sus- pended solids in depth, with larger sediment contents in lower layers though in the interface between salt water and freshwater the lowest contents appeared in middle layer. In overall, the suspended solids inflow from 8 rivers, transport southwestward, and carried by strong coastal flow in Zhujiang River estuary. Contours of sediment contents in the estuary spread further to the open sea during ebb tide rather than flood tide which reflects that the suspended solids in the estuary are land sourced.

EFFECT OF SUSPENDED SOLID PARTICLES ON UNSTABILITY OF TWO-DIMENSION MIXING LAYER

By considering the effect of suspended solid particles in the ordinary equations for two-dimension inviscid incompressible mixing layer, the Rayleigh equation and the modified Rayleigh equation are obtained. And then, by solving the corresponding eigen-value equations with numerical computational method, the relation curves between perturbation frequency and spacial growth rate of the mixing layer for the varying particle loading, ratio of particle velocity to fluid velocity and Stokes number are got. Sever al important conclusions on the effect of suspended solid particles on unstability of the mixing layer are presented in the end by analyzing all the relation curves.

RESEARCH ON STABILITY OF INTERFACE OF JET CONTAINING SUSPENDED SOLID PARTICLES

The stability equation of interface of two-phase jet and the corresponding particle-gas disturbance velocity ratio equation are derived by means of the phase-coupled model. The stability nares of interface of two-phase jet for different particle properties and the corresponding particle-gas disturbance velocity ratio curves are given out through numerical computation. Further, several important conclusions on effect of particle property on growth and propagation of disturbance of interface of two-phase jet and particle disturbance property me presented on the basis of analyses of the obtained stability curves and particle-gas disturbance velocity ratio curves. These important conclusions can play a guiding role in studying development of two-phase jet and executing artificial controls over it in project practice.

Practical Application of the Results for Optically Measured Total Suspended Solids Concentrations in the Drava River

The investigations described in this paper were performed in order to determine whether the concentrations of total suspended solids (TSS) in the Drava River, Slovenia, measured indirectly with optical sensors can be used to determine the amount and particle size of the suspended solids that can settle in stagnant water. The possibility of continuous monitoring of the TSS concentrations would allow a more reliable estimate of the amount of sediment in the accumulation lake of the planned, pumped-storage, hydroelectric power plant into which the water from the Drava River will be pumped. Therefore, during a period of one year, 90 water samples were taken directly at the optical sensors. The amount of sediments and their mineral and chemical compositions were investigated, and particle size analyses were made in 15 samples. Microbiological parameters, which included a determination of the amount of phytoplankton, zooplankton, bacteria, fungi and organic debris, were investigated in all the water samples, and the temperature and pH of the water were measured at the time when the samples were collected. The comparison of the parameters examined with the TSS concentrations showed that these concentrations can serve as a very good estimate of the amount of particles settled in the standing water, as well as of their size. These correlations are clearly expressed in the cases where the amounts of phytoplankton and organic debris in the water are low.

A Fast Predicting Neural Fuzzy Model for Suspended Solid Removal Efficiency in Multimedia Filter

Modeling of filter performance is very difficult because of complexity of the defining physical and chemical events in the filtration system whereas the knowledge of functionality of filter coefficient. The main objective of this study is to predict the performance of multimedia filter and to evaluate both the initial and transient stage of suspended solid removal efficiency depending on experimental data. Fuzzy logic has been used to build a model of multi input and one output (MISO) for the removal efficiency of multimedia filter which it consists from sand and granular activated carbon (GAC) mediums. The control parameters of (FLC) of Sugeno model are seven parameters which are media depths, media grains size for both sand and GAC, filtration rate, diameter of suspension particle, feed concentration, and operation time. The output parameter is removal efficiency of media filter whereas these data are collocated from pilot scale deep bed filter, thus, the removal efficiency of filter was modeled by 575 rules as a function of different control parameters. An adaptive of neuron fuzzy inference system (ANFIS) had used to simulate the experimental data. The simulation results were evaluated using mean absolute percentage error (MAPE), whereas the results showed that the prediction of ANFIS model has a good agreement with experimental data when the MAPE is equal to 7.0458 and fuzzy rule -based modeling proved a reliable and flexible tool to study the performance of multimedia filter. The conclusion showed that there is a relationship between flow rate, effective size and optimum bed depth for all filter media, the increment of effective size generates a higher value of optimum filter bed depth for a lower value of filtration rate. It was concluded that the optimal removal efficiency (95-100) achieved by (0.5-0.7 mm) grain size of sand, (1.5-1.9) mm grain size of granular activated carbon (GAC), with media depths should range from 0.3 to 0.6 m.

悬浮物对三亚珊瑚礁区浮游动物群落结构及其摄食的影响

随着人类活动对珊瑚礁的影响日益加剧,输入到近岸珊瑚礁区的悬浮物日益增多,不仅影响珊瑚的生理,也会对珊瑚礁生态系统基础生物生产过程产生影响。为了解悬浮物对珊瑚礁区浮游动物组成及摄食的影响,于2015年4月在三亚典型岸礁区设置了昼夜连续观测站点(W4为悬浮物浓度高的站位,W5为对照站位),分析了悬浮物波动对浮游动物群落结构的影响,并用分子生物学方法结合室内实验,研究了悬浮物对优势桡足类现场食物组成和摄食选择的影响。结果显示:两个站位叶绿素a浓度偏低,昼夜波动较大;W4站的悬浮物和叶绿素a浓度均高于W5站,但W5站悬浮物中有机颗粒物组分比例(73.69%)高于W4站(46.09%);W5站浮游动物种类多样性和丰度均高于W4站。进一步摄食分析表明,两个站位桡足类均以后生动物来源的有机碎屑为主要食物,在W4站桡足类食物组成中浮游植物的比例也相对较高,而在W5站桡足类还摄食较多的微型浮游动物。在摄食实验中,高浓度的悬浮颗粒物显著提高了红纺锤水蚤(Acartia erythraea)的滤水率和摄食率,但其食物组成却由以浮游植物为主转而以陆生植物碎屑为主,说明浓缩海水中较高的悬浮颗粒物含量限制了桡足类的摄食选择,使其摄食大部分有机碎屑作为补偿营养来源。研究结果表明,高悬浮物浓度会影响浮游动物的摄食选择,但悬浮物中高比例的有机碎屑可为浮游动物提供重要的补充食物来源,支持其维持较高的生物量。

渤南油田注水沿程水质劣化原因评价

针对渤南油田注水流程沿程水质劣化的问题,利用色谱、质谱、光谱等分析仪器检测悬浮固体颗粒的组成。结合悬浮固体颗粒组分的检测结果及水质数据,证明水中Fe^(2+)/Fe^(3+)与S^(2-)反应生成硫化物沉淀,是沿程水质劣化的主要原因。目测及机理分析表明水中溶解氧也参与了沉淀反应,即亚铁离子氧化成铁离子进而生成氢氧化铁沉淀。现场采用氧化法去除亚铁离子和硫离子,试验后硫离子含量稳定为0,总铁的质量浓度由10.65 mg/L下降到0.05 mg/L。

草鱼池塘养殖水体的悬浮物特征

为了解草鱼养殖池塘水体中悬浮颗粒物(SS)的组成结构及其变化特征,采用静沉降方式对草鱼养殖水体沉降处理,运用激光粒度分析仪探究养殖水体沉降前后悬浮颗粒物的粒径分布(PSD)变化情况、测定沉降前后水质指标变化情况及分析悬浮颗粒物沉降特性。结果显示:草鱼池塘养殖水体中产生的SS随时间延长逐渐减低,30 min后水体中SS显著降低(P<0.05),150 min后上层水体中SS可降低60%以上;静置30 min后,上下水体中SS的PSD呈现显著性差异(P<0.05),粒径大于100μm的SS沉积于底部,上层水体中的SS整体趋于小粒径分布;随着沉降时间延长,水体中SS的比表面积逐渐增加,颗粒无机物(PIM)较颗粒有机物(POM)沉降速度快,150 min后,水体SS的主要成分为POM;SS对水质有影响作用,水体中的TN、TP的质量浓度随沉降时间延长而降低(P<0.05),在120 min后趋于稳定。研究结果进一步了解草鱼养殖池塘养殖水体悬浮颗粒物沉降特性,为调控草鱼养殖池塘水体中的悬浮颗粒物提供一定的理论依据。

印染废水的透视度与SS色度相关性研究

文章探讨了印染废水的透视度与SS、色度的相关性。分别对活性、分散、直接染料的染色液、模拟印花浆液进行研究,发现对分散染料残液及浆液无法用单纯的过滤来去除色度与SS,必须通过混凝、电解、生化等方法来解决。

生物流化反应器去除生活污水中的SS

针对内循环三相生物流化床存在的问题,设计出了内循环流化床与溶气气浮相耦合的高效分离生物流化复合反应器(BFR),并考察了其对悬浮固体的去除效果。中试结果表明,在不投加混凝剂的条件下气浮分离区的最佳运行条件为:HRT=20min,工作压力=0.3MPa,回流比=20%。在该运行条件下处理清河污水处理厂未经沉淀的生活污水时(气浮反应区进水SS为347～1578mg/L),对SS的去除率可达85%,且运行稳定。

常减压装置电脱盐污水治理的工艺改造与优化

针对常减压装置电脱盐污水中H2S和可燃气体含量高、水质因含油含渣的影响不能稳定达标的突出问题。采用常压闪蒸和高效旋流溶气气浮(CDFU)相结合技术路线配套原有重力沉降除油技术工艺,有效解决电脱盐污水中高含油含渣、可燃气和硫化氢含量较高的问题,改造后石油类降低73.6%,COD(化学需氧量)降低32.7%,H2S、可燃气体和VOCS体积浓度分别下降56.85%、57.93%和38.25%。电脱盐污水水质明显改善,减少对下游污水系统的影响,消除安全隐患。