Lower Filtration Rate Research Articles

Factors related to NT-proBNP levels in HIV patients aged over 40years.

ObjectiveTo determine the levels of NT-pro BNP in HIV patients over 40 years who are receiving highly active antiretroviral therapy (HAART) and investigating potential independent clinical or laboratory factors.MethodWe determine levels of NT-pro BNP in peripheral blood of HIV patients from Costa del Sol Hospital, over 40 years.We collected epidemiological, classical cardiovascular risk factors and variables associated with HIV infection status. The qualitative variables were compared using the χ2 test. NT-proBNP levels were taken as the dependent variable. The association between these levels and the quantitative variables were studied by analysis of variance (ANOVA), and the association with the qualitative variables, using Student’s t test.ResultsNt-pro BNP levels were determined in 146 HIV patients. We assess the 10-year cardiovascular risk calculated by the Framingham equation, 59 (41.5%) were classified as low risk, 46 (32.4%) as a moderate risk and 37 (26.1%) as a high risk. The higher levels of NT-pro BNP were found in women, and in those patient with lower filtration rate and high levels of triglycerides. An association was also observed between higher levels of NT-proBNP and the recent use of lamivudine and fosamprenavir. After a multivariate analysis we found an association between higher levels of NT-proBNP and the current use of fosamprenavir and a lower glomerular filtration rate.ConclusionsWe found, with the limitations of a small serie, that higher levels of NTproBNP in HIV patients could be linked to the occurrence of cardiovascular events, this fact suggest that NTpro BNP could be used in patients at moderate or high vascular risk in order to optimise the primary prevention of vascular events.

FP330INCREASED RISK OF END-STAGE RENAL DISEASE IN PATIENTS WITH RENAL CELL CARCINOMA: A 12-YEAR NATIONWIDE FOLLOW-UP STUDY

FP330INCREASED RISK OF END-STAGE RENAL DISEASE IN PATIENTS WITH RENAL CELL CARCINOMA: A 12-YEAR NATIONWIDE FOLLOW-UP STUDY

Investigation of geometric properties of media particles and operating conditions on floating media filtration

Filtration is an effective process in removing particles that are present in water. Floating medium filter has been used in direct filtration because of its flexibility, cost savings gained by less land requirements, and less water and energy required for backwashing. The aim of this work was to investigate the effect of geometric properties of a floating medium in upflow filtration mode. A pilot plant was designed and constructed to evaluate the filtration process. Effect of physical parameters on filtration performance was also investigated. The experiments were carried out using a commonly available polypropylene floating medium. Four median grain sizes (2.28, 3.03, 3.30, and 4.07 mm) of polypropylene plastic pellets were used. Two media shapes (cubic and disc) were evaluated. Bentonite (250 mg/L ≈ 60 NTU) was used to make up the raw feed water. Three parameters that could influence the filtration performance were identified, namely: filtration velocity, media depth, and coagulant dose. The results showed that the best conditions to remove turbidity were found to be: low filtration rate (36.8 L/m2 min), longer media depth (600 mm) and optimum coagulant dose (23 mg/L). The results also indicated that the smaller plastic medium (2.28 mm) was more efficient in terms of turbidity removal than the larger medium. However, headloss development associated with smaller media was higher (109 mm of water) than that associated with larger medium (42 mm of water).

Water filtration through wood with helical cross-flow

The use of wood as a filter element for water treatment can be an efficient, low-cost alternative because wood is a renewable material. Therefore, pioneering a study to examine the possibility of filtering water through wood was advantageous. In 2002, the first experiments with wood filtration in the perpendicular direction of fibers were conducted (Correa and Sens [1]). With the continuation of this study, a new research developed as presented in this article. This study was conducted in two steps by the construction of pilot systems. The first step studied dead-end filtration and the second step studied helical cross-flow. The three species of wood studied were: caixeta (Tabebuia cassinoides Lam P. DC.), garapuvu (Schizolobium parahyba Vell. Blake), and pine (Pinus elliottii). The images obtained in the scanning electron microscope had the same approximations for all the three samples in the pores’ direction as well as in the direction of fibers. The porosity of the wood fits within the size of the microfiltration. The observation of the wood’s permeability revealed that the more porous the wood, the greater the permeability and the smaller the apparent mass. Filtration in the perpendicular direction of the fibers did not prove valuable because of its very low filtration rate and the need for high working pressure. Pine proved to be the superior option when considering the quality and production of water in the dead-end filtration. In this study, the value for wood density which is calculated to be 0.50 g/cm3 and the porosity in the range of 40% proved to be significant factors for this treatment system. This implied a correlation between wood density and its porosity when choosing wood for water filtration. With respect to the observed wood, the pore diameter with higher performance was approximately 0.02 mm. The results in the helical cross-flow filtration generated an average removal of 70% to apparent color removal and 93% for average turbidity. The working pressure did not exceed 40 psi for a filtration rate of 15 m3/m².d. The helical cross-flow filtration tests involving coagulation showed enhanced results and higher efficiency. Fouling on the surface of the wood reached a depth of 5 mm, not found in 10 mm. In summary, this treatment system exhibited improved and cost-effective results with minimal power consumption due to low working pressures.

Commercially-cultured oysters (Crassostrea gigas) exert top-down control on intertidal pelagic resources in Willapa Bay, Washington, USA

The capacity of filter feeders to reduce seston and phytoplankton concentrations in the water column has important implications for restoration and management of coastal ecosystems. We directly measured changes in chlorophyll a concentration on commercially stocked intertidal oyster beds (Crassostrea gigas) in Willapa Bay, Washington, USA by recording water properties near small drifters as they tracked parcels of water across tide flats. Chlorophyll declined 9.6% per half hour in water passing on-bottom adult oysters and 41% for longline adult oysters, whereas chlorophyll concentrations increased as water flowed across tide flats without adult oysters. Field filtration rates, which were fit to exponential declines in chlorophyll and accounted for oyster density and water depth, averaged 0.35Lg−1h−1 (shucked dry weight) for on-bottom aquaculture and 0.73Lg−1h−1 for longline culture, compared to values of 2.5–12Lg−1h−1 reported from laboratory studies of C. gigas. Field filtration rates may be lower than laboratory rates due to unfavorable field conditions (e.g., low initial chlorophyll concentrations) or masked by resuspension of benthic microalgae. In addition to distinctions among on-bottom, longline, and no-oyster habitats, Akaike's Information Criterion analysis showed temperature, initial chlorophyll concentration, and depth related to chlorophyll decline. This research corroborates mathematical models suggesting that benthic suspension feeders are exerting top-down control of pelagic production in this estuary, with strong patterns in chlorophyll emerging across extensive tideflats populated by C. gigas despite low field filtration rates.

Performance of In-Line Sediment Control Devices Under Field Conditions

. A wide variety of structural best management practices (BMPs) has been developed in the last few decades to control erosion-related problems at construction sites. Even though many BMPs exist to control erosion and sediment accumulation, there is very little research on their performance and this is even more pronounced when considering the performance of these devices working together and under field conditions. In an effort to address this issue, this study analyzes the performance of in-line devices installed at six drainage exits of a new highway under construction, all of them located upstream and 1.0 km to 2.5 km far from a surface intake in a public water supply reservoir. Altogether, three categories of devices were studied: gabions, silt fences and turbidity curtains. The performance of each device was assessed based on inspections at the construction site after heavy rains, by visually checking changes in the apparent color of the water and accumulation of sediments. Complementary, water quality monitoring data collected at the water intake were analyzed by comparing two different periods: before (from 2002 to 2007) and during (from 2008 to 2010) the construction of the highway. Results indicated that the six drainage exits with BMPs installed in-line did not affect the quality of the water at the surface intake. In addition to that, although each of these devices could not function properly due to unsatisfactory maintenance and sometimes by their own low filtration rates, all of them contributed to retain sediment and keep it close to the limits of the construction site.

Filtragem de rejeitos de minério de ferro visando à sua disposição em pilhas

A metodologia tradicional de disposição de rejeitos em forma de polpa requer grandes áreas para disposição e apresenta grande impacto ambiental e, por conseguinte, as empresas têm dificuldade na aquisição de novos licenciamentos. A proximidade de áreas urbanas e a pressão pública têm despertado a necessidade de se buscarem alternativas a essa metodologia. Uma solução viável para essa questão contribuirá com o processo de licenciamento ambiental, garantindo a sobrevivência da mineração no Quadrilátero Ferrífero. Foram realizados ensaios de filtragem em bancada com amostras de rejeitos nas principais tecnologias de filtragem: a vácuo, sob pressão, capilar e hiperbárica. Os resultados mostraram que, com exceção das lamas, é possível filtrar os rejeitos com uma boa taxa de filtragem e umidade adequada para empilhamento. A filtragem das lamas sob pressão resultou em taxa unitária de filtragem relativamente baixa e alta umidade da torta (próximo a 20%). A torta derivada das lamas poderia ser misturada à torta de rejeitos grossos e/ou o estéril da mina para permitir o seu empilhamento, porém requerendo estudos geotécnicos complementares.

Investigation of Locally Made Ceramic Filter for Household Water Treatment

This research have objective to develop and evaluate the performance of ceramic filter in using locally available material at Yogyakarta. Ceramic filter are made by pressing a mixture of clay, discarded pottery (grog) and combustible material (coconut fiber) into the molder. Curving processes are then applied to form tubular shape before firing it using kiln (1005°C). Filtration test were performed gravitationally by flowing well water into ceramic filter. Filtered water quality was complying with Indonesia drinking water quality standard (E.Coli and turbidity) although it has low filtration rate (0,461 L/Hr). The most optimum ceramic filter in turbidity and bacterial removal was composition number 10 {clay+coconut fiber 4,5%(w/w)+grog 5%(w/w)} that have average turbidity removal 88,2%, and average E. Coli removal 100%. N2 adsorption-desorption result on ceramic filter number 10 showed 0,04μm pore size, and 4,32m2/g pore surface area. The result from the XRD (X-ray diffractometer) indicates crystal structure of calcite and quartz on ceramic filter surface. Energy Dispersive X-ray (EDX) analysis showed Carbon compound as the most material constituent within the filter. Whereas micro’s photo using SEM (scanning electron microscopic) and TEM (transmitted electron microscopic) showed filter surface consists of stacked aggregates, separated by more randomly oriented particles.

Investigation of Parameters Affecting Gypsum Dewatering Properties in a Wet Flue Gas Desulphurization Pilot Plant

Wet flue gas desulphurization (FGD) plants with forced oxidation, installed at coal and oil fired power plants for removal of SO2(g), must produce gypsum of high quality. However, quality issues such as an excessive moisture content, due to poor gypsum dewatering properties, may occur from time to time. In this work, the particle size distribution, morphology, and filtration rate of wet FGD gypsum formed in a pilot-scale experimental setup, operated in forced oxidation mode, have been studied. The influence of holding tank residence time (10–408 h), solids content (30–169 g/L), and the presence of impurities (0.002 M Al2F6; 50 g quartz/L; 0.02 M Al3+, and 0.040 M Mg2+) were investigated. In addition, slurry from a full-scale wet FGD plant, experiencing formation of flat shaped crystals and poor gypsum dewatering properties, was transferred to the pilot plant to test if the plant would now start to produce low quality gypsum. The crystals formed in the pilot plant, on the basis of the full-scale slurry did, however, show acceptable filtration rates and crystal morphologies closer to the prismatic crystals from after pilot plant experiments with demineralized water. The gypsum slurry filtration rates were generally high, but a shorter residence time (10 h) and gypsum crystals experiencing breakage and/or attrition (408 h) showed slightly lower filtration rates. Both these experiments contained a higher fraction of fines, which may explain the slightly lower filtration rates. Crystals formed at a higher solids concentration and longer residence time (169 g/L and 120 h) showed a higher proportion of flat crystals, and the XRD pattern contained strong peaks at 31.1° (as the full-scale gypsum) and 29.1°, but no change in the filtration rate was obtained. It has not been possible in the pilot plant to form flat gypsum flakes with poor dewatering properties similar to those observed in full-scale plants.

A Literature Review on the Adverse Effects of Hypothyroidism on Kidney Function

Thyroid produce two important hormone of thyroxine or tetraidothyronine (T4) and triidothyronine (T3), which are involved in whole aspect of metabolism. T4 and T3 play vital role in all biochemical function, growth and development in human body. The basic metabolic pathways in kidney and every organ in human controlled by these hormones. T4 and T3 are involved in kidney function in health and diseases condition therefore the pathophysiology of kidney can be directly influenced and regulated by thyroid hormones. Kidney growth, haemodynamic, blood circulation, tubular, electrolyte balance and glomerular filtration rate (GFR) are among such crucial process. Hypothyroidism which accompanied with reduced thyroid hormone production adversely affect the renal functions, development and eventually leading to reduced weight, kidney vascular disorders, electrolyte, tubular transport imbalances, lower filtration rate and other adverse consequences of hypothyroidism. On other hand kidney diseases can also disrupt the thyroid function metabolism resulting in the subsequent hypothyroidism. It is an interesting subject in how thyroid and kidney in health and diseases closely interacted. For the ideal clinical follow up of either of thyroid and renal diseases the two organs should be simultaneously examined for a proper patient management. Close correlation of thyroid and kidney clinical teams are essential to check the cross reactions and adverse interactions which might be produced between these two vital organs to avoid misdiagnosis either of thyroid or kidney abnormalities.

Low-Damage Drilling Fluid Technology Used in Jabung Oilfield, Indonesia

Formation damage is prone to occur during drilling into the formations with medium/high permeability in Jabung Oilfield, Indonesia. To prevent formation damage and enhance productivity of oil wells, a novel low-damage drilling fluid was developed on the basis of the modification of currently used KCl polymer drilling fluid using a special technology. By virtue of the synergistic effect of ideal packing agents and film-forming agents, a sealing layer with high pressure bearing capability can be formed on the rock surface of borehole, so as to prevent drilling fluids from invading into formations effectively. It is shown from the results of numerous experiments that this drilling fluid has excellent rheological properties, very low filtration rates (API filtration rate<4mL and HTHP filtration rate≤12.5mL), good lubricity, and strongly inhibitive character to shale. Also, it exhibits remarkable effectiveness of formation protection indicated by the returned permeability as high as 88.11% and extremely low dynamic filtration rate lower than 4mL.

Evaluation of hollow-fiber ultrafiltration primary concentration of pathogens and secondary concentration of viruses from water

Tangential flow hollow-fiber ultrafiltration (HFUF) was evaluated for virus and Cryptosporidium parvum concentration from water. Recovery of viruses at a low filtration rate was found to be significantly greater than at a higher filtration rate, with the recoveries of bacteriophage MS2 at high and low filtration rates shown to be 64.7% and 98.7%, respectively. Poliovirus recoveries from tap water were similar to MS2, with recoveries of 62.9% and 104.5% for high and low filtration rates, respectively. C. parvum, which was only tested at high filtration rates, had an average recovery was 105.1%. In addition to the optimization of the primary concentration technique, this study also compared several secondary concentration procedures. The highest recovery (89.5%) of poliovirus from tap water concentrates was obtained when a beef extract–celite method was used and the virus was eluted from the celite with phosphate buffered saline, pH 9.0. When HFUF primary concentration and the optimal secondary concentration methods were combined, an average recovery of 97.0 ± 35.6% or 89.3 ± 19.3%, depending on spike level, was achieved for poliovirus. This study demonstrated that HFUF primary concentration method is effective at recovering MS2, poliovirus and C. parvum from large volumes of water and that beef extract–celite method is an effective secondary concentration method for the poliovirus tested.

Filtration rate, assimilation and assimilation efficiency in Crassostrea virginica (Gmelin) fed with Tetraselmis suecica under cadmium exposure

Crassostrea virginica is an epibentic filter-feeding bivalve of economical importance in coastal lagoons of the Gulf of Mexico, locations with increasing inputs of heavy metals such as cadmium that have become environmental stressors. In this study, feeding and assimilation of the species were evaluated as physiological indicators of cadmium exposure. For this purpose, the filtration rate (FR), food assimilation (A) and assimilation efficiency (AE) of oysters from the Mandinga Lagoon, Veracruz, México, were examined under sublethal and environmentally realistic cadmium concentrations (95 and 170 μ gCd L−1). Semi-static, 12-day bioassays were conducted with organisms placed into individual chambers and fed daily with Tetraselmis suecica. FR was calculated by measuring the depletion in algal density. Caloric contents of food and feces produced were also obtained. Condition Index (CI) and morphometric parameters were evaluated at the beginning and at the end of the assay. Total cadmium concentrations were quantified in water and tissue, and the metal bioconcentration factor (BCF) was calculated. Cadmium exposure significantly reduced FR in oysters (mean value: 0.64 L h−1 and 0.44 L h−1) from control values (1.17 L h−1). Extreme values among results demonstrate the existence of a high FR (over 4 L h−1) mainly in control oysters, and this was associated with a better physiological condition; a low FR (under 2.5 L h−1) indicated metabolic stress as a consequence of Cd exposure. A and AE were significantly modified due to cadmium external levels, and time of exposure. FR and A were linearly related, and both decreased as metal BCF increased. Cadmium bioaccumulation was linearly related with external metal levels. The physiological deterioration of native C. virginica from Mandinga Lagoon was reflected in the alteration of FR, A and AE due to cadmium exposure in concentrations considered sublethal, lowering the feeding and assimilation capability of the organisms. The weight loss and mortality recorded in the oysters exposed to the highest metal concentration, was the final consequence of the overall adverse effect of cadmium exposure.

Crassostrea virginica grazing on toxic and non-toxic diatoms

Despite high abundances of toxic Pseudo-nitzschia spp. over Louisiana oyster beds ( Crassostrea virginica; eastern oyster) there have been no documented cases of amnesic shellfish poisoning (ASP) in the state. Two possible explanations are that oysters do not readily feed on long pointed chains of Pseudo-nitzschia cells or they discriminate against toxic cells while grazing. To test these hypotheses, short-term grazing experiments were conducted with several diatoms, including the domoic acid (DA)-producing Pseudo-nitzschia multiseries (1.31 ± 0.057 pg DA cell −1) and the non-toxic Pseudo-nitzschia delicatissima, Thalassiosira weissflogii, and Ditylum brightwellii. Grazing rates on the small centric species T. weissflogii were significantly higher than on the larger and pointier D. brightwellii and either Pseudo-nitzschia species. Grazing on toxic P. multiseries and non-toxic P. delicatissima was not significantly different. Pseudofeces production was higher and feces production was occasionally lower in oysters fed Pseudo-nitzschia spp. than in oysters fed the other two diatoms. Our data demonstrate lower filtration rates of C. virginica on Pseudo-nitzschia spp. relative to the other diatoms tested and comparable filtration on toxic and non-toxic Pseudo-nitzschia spp. These findings suggest that eastern oysters do not discriminate amongst food types due to DA content.

Carbon and nitrogen relationships in the feeding and growth of the Pacific oyster, Crassostrea gigas (Thunberg)

Bivalve molluscs, in common with consumers in general, use behavioral and physiological mechanisms to balance metabolic requirements with available nutrients. This study considered how the Pacific oyster, Crassostrea gigas, meets the demands of growth and maintenance, measured in terms of carbon and nitrogen, in a variable food environment. Stoichiometry theory helped to evaluate: a) whether feeding behaviour modifies the intake of C and N given seasonal variability in food quality: b) how rates of metabolism and excretion, and C and N growth efficiencies, respond to mismatch between nutrient intake and the oysters' needs. Two field experiments in the Port Stephens estuary, near Sydney, Australia, measured feeding behaviour, metabolic and growth rates relative to seasonal changes in food supply. In a laboratory experiment, relationships between physiological rates and growth were measured to test a model of growth as a function of absorption of C and N. Potential metabolic targets for compensation were the C/N ratios of body tissues, maintenance and/or of soft tissue added as growth. C/N of whole soft issues varied little during the year (mean 5.4). In July (a time of low food availability of poor quality) growth was negligible and the C/N (maintenance) target was 6.7. In March (abundant food of high quality) growth was rapid with a high N-demand; the C/N of growth was 3.9. In November (medium food quality) there was an enhanced C-demand for glycogen storage; the C/N of growth was 7.9. Feeding behaviour changed the balance between C and N intake across months, primarily due to changes in the selection efficiency for nitrogen, which was highest at low filtration rates on particles of high C/N ratio. Nitrogen intake was favoured over C in July. In November, C-intake increased relative to N. In March, when abundant food nitrogen coincided with a high demand for growth, feeding behaviour was neutral with respect to C/N ratios. In all cases C/N of absorbed matter was greater than the C/N of growth. Growth efficiencies for carbon declined with increased C/N of ingested matter due to higher metabolic increments (SDA) when feeding on lower food quality; the metabolic costs of growth did not vary. In contrast, growth efficiencies for nitrogen did not alter with C/N for ingested matter, due in part to increased nitrogen losses, relative to tissue nitrogen content, when feeding on low C/N food. Nitrogen was therefore conserved metabolically relative to C. Both feeding and metabolic processes contributed to compensation for the mismatch between seasonally variable food quality and the demands of growth.

Characterization and prevention of formation damage for fractured carbonate reservoir formations with low permeability

Stress sensitivity and water blocking in fractured carbonate reservoir formations with low permeability were determined as the main potential damage mechanisms during drilling and completion operations in the ancient buried hill Ordovician reservoirs in the Tarim Basin. Geological structure, lithology, porosity, permeability and mineral components all affect the potential for formation damage. The experimental results showed that the permeability loss was 83.8%–98.6% caused by stress sensitivity, and was 27.9%–48.1% caused by water blocking. Based on the experimental results, several main conclusions concerning stress sensitivity can be drawn as follows: the lower the core permeability and the smaller the core fracture width, the higher the stress sensitivity. Also, stress sensitivity results in lag effect for both permeability recovery and fracture closure. Aimed at the mechanisms of formation damage, a modified low-damage mixed metal hydroxide (MMH) drilling fluid system was developed, which was mainly composed of low-fluorescence shale control agent, filtration control agent, low-fluorescence lubricant and surfactant. The results of experimental evaluation and field test showed that the newly-developed drilling fluid and engineering techniques provided could dramatically increase the return permeability (over 85%) of core samples. This drilling fluid had such advantages as good rheological and lubricating properties, high temperature stability, and low filtration rate (API filtration less than 5 ml after aging at 120 °C for 4 hours). Therefore, fractured carbonate formations with low permeability could be protected effectively when drilling with the newly-developed drilling fluid. Meanwhile, field test showed that both penetration rate and bore stability were improved and the soaking time of the drilling fluid with formation was sharply shortened, indicating that the modified MMH drilling fluid could meet the requirements of drilling engineering and geology.

Ambient fauna impairs parasite transmission in a marine parasite-host system

To understand possible factors controlling transmission of trematode larvae between first and second intermediate hosts we examined the impact of ambient fauna on parasite transmission in a marine intertidal parasite-host association. Cockle hosts (Cerastoderma edule) kept together with selected co-occurring macrozoobenthic species in mesocosms acquired a lower parasite load compared to cockles kept alone, when targeted by cercariae of the trematode Himasthla elongata. The reduction of parasite load in the cockles differed between the 7 macrozoobenthic species tested and was between 35 and 91%. Three different types of reduction could be distinguished: (1) predators (Carcinus maenas, Crangon crangon) actively preying upon cercariae, (2) non-host filter feeders (Crepidula fornicata, Mya arenaria, Crassostrea gigas) filtering cercariae but not becoming infected and (3) alternative hosts (Mytilus edulis, Macoma balthica) becoming infected by the cercariae and thus distracting cercariae from the target hosts. In addition, interference competition may occur in the form of disturbance of cockles by ambient organisms resulting in lower filtration rates and subsequently lower parasite loads. Our results suggest that the species composition and relative abundance of the ambient fauna of parasite-host systems play an important role in controlling trematode transmission rates in benthic marine systems.

Performance evaluation and mathematical modelling of granular activated carbon biofiltration in wastewater treatment

Biological filtration is an effective technique for removing organic matter from wastewater. The perfor- mance of a biofilter can be influenced by a range of operational conditions. In this study the performance of biofilters was investigated for the influence of filter media depth, influent concentrations, filtrations rates and backwashing. The results show that performance of GAC filters decreased with shallower filter bed depths. In addition, the GAC per- formed better at lower influent concentration and lower filtration rates. The daily backwash adopted to avoid the phys- ical clogging of the biofilter did not have any significant effect on the organic removal efficiency of the filter. The con- centration, activity and characteristics of the biomass are quantified and described. A mathematical model was devel- oped to simulate the organic removal of the GAC biofiltration system. The performance of the GAC filter under dif- ferent influent organic concentration levels, filtration rates and filter bed depths was adequately simulated by the math- ematical model developed for this study.

Differential timing of larval starvation effects on filtration rate and growth in juvenile Crepidula onyx

This study demonstrates that the timing of larval starvation did not only determine the larval quality (shell length, lipid content, and RNA:DNA ratio) and the juvenile performance (growth and filtration rates), but also determine how the latent effects of larval starvation were mediated in Crepidula onyx. The juveniles developed from larvae that had experienced starvation in the first two days of larval life had reduced growth and lower filtration rates than those developed from larvae that had not been starved. Lower filtration rates explained the observed latent effects of early larval starvation on reduced juvenile growth. Starvation late in larval life caused a reduction in shell length, lipid content, and RNA:DNA ratio of larvae at metamorphosis; juveniles developed from these larvae performed poorly in terms of growth in shell length and total organic carbon content because of “depletion of energy reserves” at metamorphosis. Results of this study indicate that even exposure to the same kind of larval stress (starvation) for the same period of time (2 days) can cause different juvenile responses through different mechanisms if larvae are exposed to the stress at different stages of the larval life.

Removal of contaminants from aqueous solutions by beds made of rejects of the lightweight aggregates production

This work describes the attempt to reuse rejected sieved fractions from the lightweight expanded clay aggregates production, as filter bed, used in the removal of some water contaminants, namely nickel, lead and suspended particles, as an alternative to land filling deposition. Expanded clay fractions and materials used for efficiency comparison were first characterised, by means of physical, chemical and mineralogical tests, in such a way that possible factors, on which removal depends, could be determined. Besides the classical purpose of suspended particles’ removal, assay on the removal of heavy metals were also performed through the filtration in fixed beds. Experiments were performed at different contaminant concentrations and by testing several operational conditions. The performance is better for all the studied contaminants using beds made of smaller sieved fractions, 0/0.5 mm, showing higher packing density values (straining is favored), and for lower filtration rates which improve contact time between pollutants and filtration material. Pb(II) removal was higher than Ni(II) one. When comparing with the traditional filtration materials, lightweight aggregates rejects demonstrate their good performance, once it was more effective than sand, considering suspended particles’ removal, and for heavy metal removal, efficiencies were similar or higher than those found for granular activated carbon (GAC).