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.

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.

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.

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.

The flocculation research on treating suspended solids contained mine drainage through goaf

Mine drainage could be filtered and purified through goaf. This innovative technique shows merits, such as high treatment efficiency, remarkable economic benefit and extensive wastewater recycle use. However, it was detected that capacities of purifying mine drainage for goaf were decreased after a period of application. As a result, the effluent could not meet the standard of recycle water. To solve the problem, coagulant was considered to add into mine drainage reducing its high turbid degrees to certain level. After the preliminary flocculation treatment, mine drainage was piped into goaf to purify. In this way, the load of goaf was eased up. Its usage time was also prolonged. Therefore, this paper carried out the coagulation-flocculation jar test for mine drainage to discuss the flocculation parameters. By the experiment, 10 % iron trichloride is selected from four inorganic coagulants as the optimum coagulant. The optimum dose, PH value and sedirs6-7 and 25 min. Velocity mentation time are respectively 2 mL per 800 mL Wastewater gradient G during the process of mixing and reaction is 696 .And the value of GT is 6.264 × 10^5. The values of G and GT will supply the basis for the design of flocculation pool in the project. The flocculation parameters will be significant for the reference of practice.

Characterization of Suspended Solids and Heavy Metal Distributions during First Flush in Highway Runoff

Nonpoint source pollution has gradually received attention during stormwater flush in highway runoff. The understanding the pollutant characteristics will be criticat issue to treat these types of pollution. In the present study, two monitoring stations were selected to measure hydrology and to take sampling during first flushing events at the Zhong-Shan freeway and East-West expressway in the Miaoli County, Taiwan. The results of monitoring stations in 2007 storm events found that normally the peak concentrations of total suspended solids （TSS） and heavy metals occurred at the initial stormwater and then the concentrations decreased when the measured time elapsed. The highest and lowest heavy metal concentrations were Fe and Ni, respectively, during the stormwater. Particle size distribution （PSD） mostly ranged from 12μm and 96 μm at two measured sites. The event mean concentrations （EMCs） and loadings of TSS and heavy metals were also correlated with total runoff and total rainfall.

Simultaneous determination of three classes of antibiotics in the suspended solids of swine wastewater by ultrasonic extraction,solid-phase extraction and liquid chromatography-mass spectrometry

This work describes a systematic approach to the development of a method for simultaneous determination of three classes of veterinary antibiotics in the suspended solids （SS） of swine wastewater, including five sulfonamides, three tetracyclines and one macrolide （tiamulin）. The entire procedures for sample pretreatment, ultrasonic extraction （USE）, solid-phase extraction （SPE）, and liquid chromatography-mass spectrometry （LC-MS） quantification were examined and optimized. The recovery efficiencies were found to be 76%-104% for sulfonamides, 81%-112% for tetracyclines, and 51%--64% for tiamulin at three spiking levels. The intra-day and inter-day precisions, as expressed by the relative standard deviation （RSD）, were below 17%. The method detection limits （MDLs） were between 0.14 and 7.14 μg/kg, depending on a specific antibiotic studied. The developed method was applied to field samples collected from three concentrated swine feeding plants located in Beijing, Shanghai and Shandong province of China. All the investigated antibiotics were detected in both SS and liquid phase of swine wastewater, with partition coefficients （logKd） ranging from 0.49 to 2.30. This study demonstrates that the SS can not be ignored when determining the concentrations of antibiotics in swine wastewater.

Modeling of secondary treated wastewater disinfection by UV irradiation: Effects of suspended solids content

This work aimed to study UV-resistant strains of Pseudomonas aeruginosa, to propose a formulation of the kinetics of secondary treated wastewater disinfection and to underline the influence of suspended solids on the inactivation kinetics of these strains. Some investigations were carried out for the validation of some simulation models, from the simplest, the kinetics model of Chick-Watson reduced to first order, to rather complex models such as multi-kinetic and Collins-Selleck models. Results revealed that the involved processes of UV irradiation were too complex to be approached by a simplified formulation, even in the case of specific strains of microorganisms and the use of nearly constant UV radiation intensity. In fact, the application of Chick-Watson model in its original form is not representative of the kinetics of UV disinfection. Modification, taking into account the speed change during the disinfection process, has not significantly improved results. On the other hand, the application of Collins-Selleck model demonstrates that it was necessary to exceed a least dose of critical radiation to start the process of inactivation. To better explain the process of inactivation, we have assumed that the action of disinfectant on the survival of lonely microorganisms is faster than its action on suspended solids protected or agglomerated to each others. We can assume in this case the existence of two inactivation kinetics during the processes （parallel and independent） of the first-order. For this reason, the application of a new kinetic model by introducing a third factor reflecting the influence of suspended solids in water on disinfection kinetics appeared to be determinant for modeling UV inactivation of P. aeruginosa in secondary treated wastewater.

Surface clogging process modeling of suspended solids during urban stormwater aquifer recharge

Aquifer recharge, which uses urban stormwater, is an effective technique to control the negative effects of groundwater overexploitation, while clogging problems in infiltration systems remain the key restricting factor in broadening its practice. Quantitative understanding of the clogging process is still very poor. A laboratory study was conducted to understand surface physical clogging processes, with the primary aim of developing a model for predicting suspended solid clogging processes before aquifer recharge projects start. The experiments investigated the clogging characteristics of different suspended solid sizes in recharge water by using a series of one-dimensional fine quartz sand columns. The results showed that the smaller the suspended particles in recharge water, the farther the distance of movement and the larger the scope of clogging in porous media. Clogging extents in fine sand were 1 cm, for suspended particle size ranging from 0.075 to 0.0385 mm, and 2 cm, for particles less than 0.0385 mm. In addition, clogging development occurred more rapidly for smaller suspended solid particles. It took 48, 42, and 36 hr respectively, for large-, medium-, and small-sized particles to reach pre-determined clogging standards. An empirical formula and iteration model for the surface clogging evolution process were derived. The verification results obtained from stormwater recharge into fine sand demonstrated that the model could reflect the real laws of the surface clogging process.

Export of nutrients and suspended solids from major Arctic rivers and their response to permafrost degradation

The rapid warming of the Arctic has led to permafrost degradation,accelerating the transport of terrestrial materials by rivers.The quan-titative assessment of riverine nutrients and total suspended solids(TSS)flux is important to clarify the land-ocean connections in the Arctic.However,much is unknown about the estimates of these components from direct measurements in the Arctic rivers and the response of the components to permafrost degradation.Here,we report the results from the Arctic Great Rivers Observatory(Arctic-GRO)for the six major Arctic rivers(Yenisey,Lena,Ob',Mackenzie,Yukon,and Kolyma)to investigate the riverine exports of TSS,total dissolved nitrogen(TDN),nitrate(NO3-),bicarbonate(HCO3-),total dissolved phosphorus(TDP),and phosphate(PO43-).The results showed that from 2004 to 2017,the annual TSS,TDN,and NO3-exports to the Arctic Ocean were approximately 106,026 Gg,692 Gg,and 130 Gg,respectively,and the HCO3-,TDP,and PO43-exports were approximately 79,092 Gg,32 Gg,and 18 Gg,respectively.There were remarkable variations in component concentrations and fluxes between seasons.More than 80%of the TDN,TDP,PO43,and TSS exports mainly occurred in spring and summer,and a high HCO3-flux was recorded in summer,while a high NO3-flux in some rivers occurred in winter.The active layer thickness was significantly positively correlated with the annual TDN,NO3-,and HCO3-exports.In addition,the HCO3-flux of the six Arctic rivers increased by 247 Gg per year during 2004-2017.The positive relationship between the active layer thickness and river discharge indicates that permafrost degradation accelerated rivefine carbonate,nitrogen,and phosphorus exports.This study demonstrates that riverine exports play an important role both in the Arctic terrestrial and marine ecosystems,and permafrost degradation will likely increase the riverine material exports to the ocean.

Effect of the exposure to suspended solids on the enzymatic activity in the bivalve Sinonovacula constricta

Aquatic animals are susceptible to sudden changes of their living environment but they adopt strategies to cope with adverse environmental challenges.Contamination by suspended solids,often associated with a dramatic change in the concentrations of important water-quality variables is a frequent occurrence in China's coastal waters and estuaries.Here we studied the impact of suspended solids on the activities of the antioxidant enzymes superoxide dismutase(SOD)and catalase(CAT),as well as adenosine triphosphates(including Na^(+)K^(+)-ATPase,Mg^(++)-ATPase,Ca^(++)-ATPase)and H^(+)K^(+)-ATPase in the gills and visceral mass tissues of the molluscan bivalve Sinonovacula constricta exposed(4,8,12,16,20,and 24 days)to various concentrations of suspended solids.Our results showed that the antioxidant enzymes cooperated closely to effectively scavenge superoxide anion free radicals and H2O2(which can ultimately inhibit gill activity)through the modification of SOD and/or CAT enzymatic activities.ATPases activity(considered to be a sensitive indicator of toxicity)could play an effective role in the maintenance of functional integrity of the plasma membranes as well as some other intracellular functions.After the exposure,a decrease in the Nat K^(+)-ATPase,Mg^(++)-ATPase,and Ca^(++)-ATPase activity of the gills was observed suggesting that they were inhibited by the treatments.These results also indicated that,from day 4 to day 16,exposure to high concentrations of suspended solids had an inhibitory effect on the activity of H^(+)-K^(+)-ATPase in the visceral mass of S.constricta.However,after a period of adaptation the H^(+)-K^(+)-ATPase activity was restored to original levels.Our results suggest that long-term exposure to high levels of suspended solids disturb osmoregulation,gastric acid secretion and digestion,cause oxidative damage,as a consequence of antioxidant enzymes inactivation which eventually damages the gills,affect the food intake and transformation,ultimately resulting in systems failure and eventually death.

Enhancing the total organic carbon measurement efficiency for water samples containing suspended solids using alkaline and ultrasonic pretreatment methods

In this study,we investigated the effect of sample pretreatments(ultrasonication and alkaline extraction)on total organic carbon(TOC)measurements for water samples containing suspended solids(SS)of four different origins(algae,soil,sewage sludge,and leaf litter)to more clearly assess the impact of particulate organic carbon(POC)in water.The effects each of ultrasonication(power,pulse,etc.)and alkaline extraction condition(concentration,time,etc.)on the TOC recovery and precision were investigated,and the results were compared with those of a new sample pre treatment method combining both methods.Alkaline treatment(0.01 mol/L NaOH)showed higher precision than ultrasonication(100/5 on/off pulse),and notably,the differences among the measured TOC values in samples of different origins were also further reduced in the alkaline treatment.This suggests that the ultrasonic pretreatment results can be mainly attributed to the increase in POC recovery through particle size reduction,whereas the alkaline treatment results are achieved through the enhancement of POC solubilization.It is also particularly noteworthy that a higher TOC recovery of 87.6%±7.4%with a higher precision of 8.4%could be obtained using the combined method,compared to each treatment(ultrasonic:TOC recovery 34.7%,relative standard deviation 63.1%;alkaline:49.6%and 23.0%,respectively).Thus,simultaneous pretreatment with ultrasonication and alkaline extraction is expected to increase the oxidation rate of organic matter and the homogeneity of the samples,minimizing the loss of POC measurement values,and thereby improving the reliability of the TOC measurements of water samples containing SS.

Tidal variation of total suspended solids over the Yangtze Bank based on the geostationary ocean color imager

Hourly mapping by a Geostationary Ocean Color Imager was used to reveal the spatial pattern and tidal variation of total suspended solids(TSS)over the Yangtze Bank in the Yellow and East China Seas during the winter.The TSS form a tongueshaped structure,which decreases further offshore in a stepwise manner.The stepwise change is separated by two fronts of TSS,which are located near the 20-m and 50-m isobaths.The tidal variation of TSS concentration during the study period is evident and can be divided into three stages:decay,maintenance,and growth.Compared with the relatively stationary TSS during the maintenance stage,drastic changes exist during the decay and growth stages.In terms of tide-induced mixing,the dynamic analysis shows that both the topography and the tidal currents play an important role in the spatio-temporal variation of TSS during the tidal period.In particular,spatial distribution is primarily determined by the topography,whereas the temporal variations in tidal scale are determined by the tidal currents.

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

Chlorophyll α（ch1-α） and suspended solid concentrations are two frequently used water quality parameters for monitoring a lake. Traditional measurement of ch1-α and suspended solids, requiring laborious laboratory work, which is often expensive and time consuming. Hyperspectral remote-sensing measurement provides a fast and easy tool for estimating water trophic status. In situ hyperspectral 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 ch1-α concentration, and moved to infrared when algal bloom occurred. The reflectance ratio of R702/R685 was well correlated with ch1-α when water surface in no algal bloom case and the correlation coefficient was better if absorption of phycocyanin was considered. The reflectance ratio R620/R531 was highly correlated to the concentration 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 concentration.

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.

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.

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.

Experimental Study on Application of A Charging Flocculation Agent for Treatment of Turbidity and Suspended Solid in Catfish Farming Water in Vinh Long Province

The electrically charged flocculation agent Kiyomaru was made on the basis of activating surface sand, clay, volcanic ash and then combined with strong electrical charge on the surface. Thus, it is the flocculant with natural and inorganic origin including 24.7% Na, 11.5% Al, 19.6% Si, 22.5% S, 1.8% K, 19.0% Ca and 0.9% Fe. The experimental results showed that the Kiyomaru is a flocculation agent with ability to treat the turbidity and suspended solid in the catfish farming waters with very high sedimentation rate and removal efficiency. The efficiency of turbidity removal is from 98.7% to 99.1%, while that for TSS removal is from 93.5% to 95.2% using 0.2 mg/L of the flocculation agent. Beside those, the agent can remove the organic matters （BOD, COD） from 21.4% to 26.7%, Total N from 32.4% to 33.9% and Total P from 85.4% to 89.3%. When the concentration of this flocculate agent is 0.2 g/L, turbidity treatment efficiency can range from 98.7% to 99.1%; TSS treatment efficiency can range from 93.5% to 95.2%. Besides, this flocculation agent is also capable of reducing 21.4%-26.7% of the organic matter, 32.4% to 33.9% of Total N and 85.4% to 89.3% of Total P.

Study on Effect of Performance on Excess Sludge Disintegration by Ozone

In order to study the effect of excess sludge ozonation, a continuous experiment in lab scale process was carried out. During the treatment process, a high level of ozone was produced by the electrolysis-type ozone generator, and various parameters, such as Soluble Chemical Oxygen Demand （SCOD）, Mixed Liquor Suspended Solids （MLSS）, Mixed Liquor Volatile Suspended Solids （MLVSS）, pH and so on, which char- acterize sludge were investigated. A substantial reduction in the volume of sludge and the release of intracellular materials were observed： SCOD proliferated as a consequence of extending the ozone feeding time; MLSS and MLVSS, especially the ratio of MLVSS to MLSS, dwindled as the action time rose. Through analyzing the effluent quality and excess sludge activity, the sludge-water volume mixture ratio of 1 ： 20 with 50 -60 minutes＇ oxidation treatment was found to be the optimal condition for ozonic disintegration of excess sludge. A remarkable sludge reduction rate of 57% could be achieved under the ozone feeding time of 40 minutes, which revealed the optimal action time.