Clay Pellets Research Articles

Hydroponic pepper growing on baked clay pellets

Nowadays one of the most important issues of greenhouse vegetable production in soilless media is the protection of the environment, in particular, the selection of the root medium to be applied. The objective of the trial was to test the applicability of baked (expanded) clay granules in hydroponic pepper growing with special respect to the growing pot (plastic tubes and buckets with bottom and lateral holes). From the result of the experiment it can be concluded that baked clay pellets, similarly to rockwool, are a suitable medium for providing root anchorage for pepper, however, it is necessary to examine some technological issues (e.g. fertilization, irrigation) prior to starting a large scale commercial cultivation. Relative to the three growing containers tested, it can be concluded that with the 4-8 mm crushed clay pebbles cultivation can be carried out successfully both in the white plastic tube and in the bucket, with the latter it is recommended to locate the drainage holes on the side of the growing container (at 6 cm from the bottom of the bucket).

Hydrothermally altered clayey sediments in the rift zone of Iceland (influence of microbiota on accumulation of minor elements)

Results of the first detailed study of mineral and chemical compositions in the rift zone of Iceland near the town of Hveragerði are presented. The major clayey components represented by dioctahedral smectites (mainly, montmorillonite with variable Fe contents) are associated with the subordinate kaolinite. The geological setting, timing, and composition of metasomatic clay minerals and their synthesized counterparts precipitated from solution in the course of interaction of hot groundwaters with basaltic volcanics and sedimentary clayey rocks are considered. Based on textural-structural features and (or) compositions, the sediments are divided into three types: (1) massive unsorted sediments with abundant fine-grained sand to silt-sized clay pellets, (2) horizontally laminated clayey sediments, and (3) organogenic sediments. The massive unsorted sediments enclose remnants of microorganisms replaced by smectite, while laminated clayey sediments host a siliceous layer with abundant mineralized remains of filamentous microorganisms. Clayey rocks of hydrothermally altered hyaloclastites and sediments related to their redeposition are similar in the composition of petrogenic elements. However, they differ notably from each other in the contents of some minor elements (Au, As, Se, Sb, and Hg). Increase in the share of minor elements in sediments is explained by the active influence of bacteria and fungi on their accumulation. The data obtained shed light on some specific features in the composition of clayey rocks, which can be used for mud cure of arthritis and rheumatism in the Health and Rehabilitation Clinic of the Nature Health Association of Iceland, Hveragerði.

Long-term, low-maintenance storage of Acanthamoeba strains

A simple, low cost method is described for the long-term storage of the potential human pathogen Acanthamoeba. Amoebae are placed in dried, sterile clay pellets within which they form cysts that remain viable and pure for at least 5 years. This method compares favorably with other storage methods and requires no specialist equipment. We have demonstrated that amoeba stored by this method retain both their pathogenic potential and their small subunit ribosomal DNA sequence type.

Adsorption of Crude Oil on Na+-Montmorillonite

The interaction between a natural Na+-montmorillonite and a crude oil sample containing 2.5 wt % of asphaltene and 6.4 wt % of polar species is studied as a function of time. The microscopic and the macroscopic mechanisms of diffusion are examined and discussed. At a microscopic scale, diffusion of crude oil within the clay interlayer space is a slow and a continuous process with the formation of O/W microemulsions within the d(001) space, which involves those crude oil polar molecules with tensoactive properties, interlayer water molecules, and the clay Na+ interlayer cations. At a macroscopic scale, the diffusion of the organic species is also a slow but stepped process. At the beginning, such a process is controlled by a concentration gradient (the Fick law) of crude oil species which diffuses into clay pellet, and it is followed by a viscous flow-type diffusion, when the compacted clay mineral pellet is surrounded by a thick O/W emulsion of crude oil, clay colloids, and water expulsed from the interlayer space.

Laser-induced breakdown spectroscopy for space exploration applications: Influence of the ambient pressure on the calibration curves prepared from soil and clay samples

Recently, there has been an increasing interest in the laser-induced breakdown spectroscopy (LIBS) technique for stand-off detection of geological samples for use on landers and rovers to Mars, and for other space applications. For space missions, LIBS analysis capabilities must be investigated and instrumental development is required to take into account constraints such as size, weight, power and the effect of environmental atmosphere (pressure and ambient gas) on flight instrument performance. In this paper, we study the in-situ LIBS method at reduced pressure (7 Torr CO 2 to simulate the Martian atmosphere) and near vacuum (50 mTorr in air to begin to simulate the Moon or asteroids' pressure) as well as at atmospheric pressure in air (for Earth conditions and comparison). Here in-situ corresponds to distances on the order of 150 mm in contrast to stand-off analysis at distance of many meters. We show the influence of the ambient pressure on the calibration curves prepared from certified soil and clay pellets. In order to detect simultaneously all the elements commonly observed in terrestrial soils, we used an Echelle spectrograph. The results are discussed in terms of calibration curves, measurement precision, plasma light collection system efficiency and matrix effects.

Recovery and fate of three species of marine dinoflagellates after yellow clay flocculation

The recovery and fate of three species of dinoflagellates, Alexandrium tamarense, Cochlodinium polykrikoides and Scrippsiella trochoidea, after having been sedimented by yellow clay, were investigated in the laboratory. The effect of burying period in yellow clay pellet and mixing on the recovery of settled algal cells were studied. The morphological changes of algal cells in yellow clay pellet were also tracked. Results showed that there was almost no recovery for A. tamarense and C. polykrikoides, and the cells decomposed after 2-3 days after visible changes in morphology and chloroplasts. There was some recovery for S. trochoidea. Moreover, S. trochoidea cysts were formed in clay pellet during the period of about 14 days, with the highest abundance of 87 000 cysts g(-1) clay and the incidence of cyst formation of 6.5%, which was considered as a potential threat for the further occurrence of algal blooms. S. trochoidea cysts were isolated from yellow clay and incubated to test their viability, and a germination ratio of more than 30% was obtained after incubation for 1 month. These results showed the species specificity of the mitigation effect of yellow clay. It is suggested that cautions be taken for some harmful species and thorough risk assessments be conducted before using this mitigation strategy in the field.

Structure‐Property Relationships of New Water‐Soluble Grafted Starches with Amphoteric Character

AbstractIn an attempt to develop an environmentally friendly, multifunctional mud additive for oilfield drilling treatment, new water‐soluble grafted starches with amphoteric character were prepared by grafting the mixed monomer system of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) and 2‐(dimethylamino)ethyl methacrylate (DMAEM) onto naturally occurring potato starch, and characterized by IR and composition analyses. Their structure‐property relationships with respect to the hydration suppression of the swellable clay and the control of mud rheology were studied with the help of clay hydration‐swelling test, mud rheology test, and SEM observation. It has been found that the grafting of DMAEM enhances the inhibition effectiveness of clay hydration‐swelling and that the grafting of AMPS increases the viscosity of the treated muds and the tolerance to added salt. Compared with the partially hydrolyzed polyacrylamide with a degree of hydrolysis of 16%, a typical polymeric additive used in current drilling fluids, such grafted starch with suitable grafting percentage and composition has some distinct advantages in the formulation of water‐based drilling muds.Swelling percentage (Sp) of the clay pellets as a function of hydration time (t) in water and various sample solutions.magnified imageSwelling percentage (Sp) of the clay pellets as a function of hydration time (t) in water and various sample solutions.

Coal and conglomerate in the Newcastle Coal Measures—coeval facies or temporally unrelated?

In the Central Coast region of the Sydney Basin, the Vales Point, Wallarah and Great Northern Coals coalesce and comprise the topmost unit of the Late Permian Newcastle Coal Measures. These coals reach a combined thickness of 8 m and, in places, are separated by 50-m-thick conglomeratic, incised valley fills at several stratigraphic horizons. Early Triassic, terrestrial sedimentary rocks unconformably onlap onto the eroded coal. Although the coalesced coals are remarkably free of siliciclastic interbeds, coal plies (subsections) have been correlated for more than 20 km using brightness profiles (lithotypes) and gamma-ray logs. Plies average about 0.5 m thick and indicate that the original peat was deposited episodically. The concept that coal originated from low-lying peat mires on flood basins adjacent to, and coeval with, active river systems is not supported here. Instead, correlations show that gravel was deposited at a time that equates to the hiatus between coal plies. Gravel-filled incised valleys were eroded into peat mires, removing all peat in the deepest places. Where the coals are coalesced, the only evidence for adjacent, thick conglomerate is a gamma-ray spike and a thin clay pellet layer of altered volcanogenic fragments. It is proposed that the coal is composed of individual plies originating from raised peat mires that grew during cyclical base-level rises. Afterwards, the mires became dormant during base-level falls, creating a hiatal surface above the degrading peat. During base-level fall, the increasing gradient initiated erosion of an incised valley into the dormant peat mire. Subsequently, as base level rose again, fluvial gravel aggraded in the valley. When the water table rose to the top of the incised valley, the flanking dormant peat mire was reactivated, initiating the accumulation of another ply above the hiatal surface. As peat grew and accumulated in raised mires, the sediment-filled incised valley may have resembled a muddy, estuarine body of water, no longer capable of transporting the coarse clastic bed load it did at times of lower base level. Repetition of base-level rise and fall is considered the main controlling factor in producing vertically stacked coal plies separated by hiatal and erosional surfaces, split in places, by thick conglomerate.

Ammonia removal from prawn aquaculture water using immobilized nitrifying bacteria.

Intensive prawn aquaculture in tropical regions is associated with high concentrations of total ammoniacal nitrogen (TAN) as a result of high rates of prawn excretion and feed loading. Excessive TAN can adversely effect productivity and result in adverse impacts on coastal waters. Cultures of indigenous nitrifying bacteria were enriched from intensive prawn aquaculture pond water using continuous and batch enrichment techniques. Cultures were capable of TAN removal over a wide range of initial TAN concentrations - up to 200 mg/l. Cultures were immobilized onto porous clay pellets to enhance cell density and applied to culture medium and TAN-augmented pond water under aerobic conditions to determine TAN removal proficiency. Immobilized cultures were able to achieve a high TAN removal proficiency in pond water--even at a low density of 0.1 pellet per liter. A concentration of less than 0.5 mg TAN/l could be maintained under a fed-batch condition of 3.2 mg TAN/l per day, after an initial 2-day lag phase. A simplified and effective culture enrichment process was developed for culture immobilization onto pellets using TAN-augmented pond water. Overall, pellet immobilization of indigenous nitrifying bacteria represents a potentially effective TAN control system for prawn aquaculture in low-cost, but intensive tropical prawn farms.

Early diagenetic pyrite morphology in a mudstone-dominated succession: the Lower Jurassic Cleveland Ironstone Formation, eastern England

Abstract Diagenetic pyrite in the mudstones and ironstones of the Lower Jurassic Cleveland Ironstone Formation of eastern England exhibits two distinct morphologies: framboidal pyrite, commonly associated with organic matter, and euhedral pyrite, associated with detrital clay pellets. These two morphologies are mutually exclusive in occurrence. Framboidal pyrite is present in clay-rich mudstones, ooidal ironstones, apatite-rich units and some silt-rich mudstones. Euhedral pyrite is present in silt-rich and sand-rich mudstones. δ34S isotopic analysis of six samples of pyrite suggests that both types of pyrite morphology precipitated during early diagenesis from porewaters with open access to overlying sea-water, although both probably acted as sites for continued pyrite precipitation during burial. It is proposed that framboidal pyrite precipitated from iron-dominated porewaters at sites of sulfide supply (i.e. in the region of organic matter as a result of bacterial sulfate reduction) where, locally, sulfide production rates were high enough for porewaters to reach supersaturation with respect to FeS. Euhedral pyrite also precipitated from iron-dominated porewaters, but sulfide production rates from organic matter was such that FeS saturation was not reached at the sites of sulfide production. Instead, euhedral pyrite was precipitated directly from porewater when FeS2 saturation was reached. The control over pyrite morphology was probably the amount and reactivity of the organic matter within the deposited sediments. The sand-rich mudstones contained less reactive organic matter due to clastic dilution and deposition in shallower environments with O2-rich bottom waters. The ironstones and apatite-rich units were deposited under very low sedimentation rates, and as a result organic matter contents were very low and iron reduction dominated early diagenesis, which inhibited sulfate-reduction. The presence of minor framboidal pyrite within these units, however, suggests that sulfide reduction took place in micro-environments during early diagenesis.

Tolerance and biodegradation of m-toluate by Scots pine, a mycorrhizal fungus and fluorescent pseudomonads individually and under associative conditions.

The tolerance to, and degradation of m-toluate by Scots pine (Pinus sylvestris), a symbiotic mycorrhizal fungus (Suillus bovinus) and Pseudomonas fluorescens strains, with or without m-toluate-degrading capacity, was determined individually and in all symbiotic/associative plant-microbe combinations. Fungal survival on medium with m-toluate was increased in co-culture with the degradative bacterial strains on agar plates (up to 0.02%, w/v). When fungi were grown in mycorrhizal association with Scots pine seedlings in test-tube microcosms containing expanded clay pellets and growth media, the fungus was able to withstand m-toluate concentrations up to 2.0%, w/v in all treatments. The seedling tolerance remained unaltered regardless of the presence or absence of mycorrhizal fungi or biodegradative bacteria. Reduction in m-toluate levels was only detected in treatments inoculated with bacterial strains harbouring TOL catabolic plasmids. The plant and fungus, alone or in mycorrhizal symbiosis, were unable to cleave m-toluate. The presence of easily available plant-derived carbon sources did not impede m-toluate degradation by the bacteria in the mycorrhizosphere.

Sorption and diffusion of chlorinated methanes in moist clay

AbstractThe dynamic behavior of chlorinated methanes in clays exposed to relative humidities (RH) from 0 to 80% was investigated with the single‐pellet pulse‐response moment technique. Values of effective diffusion coefficients obtained from zeroth moment analysis differed only slightly for dry and moist clay pellets. When the clay pellet was dry, equilibrium adsorption constants of dichloromethane (D), trichloromethane (T), and carbon tetrachloride (C) at the gas‐mineral interface were determined from first moments to be 118, 92, and 90, respectively. Dryness factors (dry fraction of surface area) for clays with RH of 5, 20, 40, and 60% were also calculated from first moments as 0.5, 0.1, 0.04, and 0.01, respectively. When the pore surfaces were covered with the water film (dryness factor was 0 for the pellet at RH 80%), overall equilibrium adsorption constants for the same tracers (D, T, C) at the gas‐water and water‐mineral interfaces were determined to be 7.5, 7.2, and 3.6, respectively.

Petrography and diagenesis of the Thames Group at Whitecliff Bay, Isle of Wight, UK

Previous studies of the Thames Group have emphasized stratigraphical or mineralogical aspects of the formation. We have used a combination of field observation, hand specimen description, optical and back-scattered electron petrography and X-ray diffraction to identify textures (grain size, bioturbation etc.), detrital, synsedimentary and diagenetic components. With these data lithologs have been constructed to describe the diverse lithologies which constitute the London Clay. Early diagenetic mineral assemblages are closely linked to depositional rate. Hiatus surfaces are associated with concentrations of glauconitic clay pellets. Bedded siderite concretionary carbonates were precipitated by diagenetic processes, below relatively brief hiatus surfaces, whilst ovoid ferroan calcite concretions were deposited during periods of very slow deposition. The glauconitic sandy fissures in the mudrock intervals of Divisions A and B are interpreted as storm deposits. The regular 1-1.5 m spacing of these sands is evidence of rhythmic sedimentation.

Landscape and Soil Development on Monaro Basalt West of Nimmitabel, New South Wales

Prolonged stability of the southern tableland of NSW, developed on early Tertiary Monaro basalt, is evident from weak landscape dissection and numerous small lakes. However, poorly developed soils and weathered zones are inconsistent with prolonged Cainozoic weathering or formation under climates substantially different to the present. Thin Holocene sediments are also at variance with the sizes of the lake basins. Low depositional landforms, termed ‘lake shadows’, occur on the eastern perimeters of most lakes, and comprise clay pellets blown from basin floors during dry phases. Deflation, dominantly during Quaternary glacial periods, and reactivated today, is responsible for the thin soils and sediment cover. The lake basins are partly solutional and partly deflational features. The modern soil cover reflects the modern climate.

A novel adsorption-anaerobiosis column for the removal of persistent organics from contaminated water

A novel adsorption-anaerobiosis column (AAC) system was used to treat persistent organics, namely neopentanoic acid (NPA, at 0.5 g l −1) and 2-ethylhexanoic acid (EHA, at 1.0 g l −1), in contaminated water. The fire-expanded clay pellets that were used to pack the column served as an adsorbent for organic contaminants and as a carrier for anaerobic biofilm immobilization. The AAC system could remove 75% of the NPA and 98% of the EHA at a hydraulic retention time (HRT) of 2 days. The system could recover from a shock load equivalent to a 150% increase in hydraulic and organic loads, caused by a sudden decrease of HRT from 5 to 2 days.

Properties of fly‐ash bricks produced for environmental applications

Abstract The effects of pressure and temperature on preparation of bricks made from fly ash have been investigated. Bricks from Texas lignite fly ash and fly ash‐clay (kaolinite or montmorillonite) mixtures were prepared. It has been found that bricks with 20% kaolinite and 5% montmorillonite have green strengths high enough to handle without any additives. Samples were pressed under the pressure ranging from 35 MPa to 350 MPa. Lamination occurred at pressures higher than 270 MPa and plerospheres cracked under applied pressure. Fly ash with and without clay pellets were fired at 1000°C for 3 hours. Surface and bulk properties of fired and unfired samples were investigated and devitrification/sintering processes analyzed by x‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy‐energy dispersive spectroscopy (SEM‐EDS), and x‐ray photoelectron spectroscopy (XPS) techniques and the results are reported.

Pelletal structures in Peruvian upwelling sediments

Late Quaternary sediments from the Peru upwelling zone have been investigated using backscattered electron imagery. The dysaerobic to anaerobic conditions which persist within the strong oxygen minimum zone intersecting the shelf and upper slope sediments, have resulted in the preservation of a wide range of microscopic fine structure relating to biological activity. Two forms of pelletal structures are present: pellets and aggregate structures. (1) Pellets are oval in cross section with a mean diameter of 610μm and sharp boundaries; three common pellet types have been identified: (a) crushed diatom and clay pellets; (b) intact diatom pellets; and (c) silt pellets. (2) Aggregate structures are smaller than pellets with a mean diameter of 360 μm. They have indistinct boundaries and may be composed either of pure diatom ooze or a mix of clay, silt and diatoms. The size, shape and mode of occurrence of aggregate structures suggest that they are the product of a meiofauna, redistributing the topmost sediment during periods of very slight increases in oxygen. Most of the crushed diatom/clay pellets and intact diatom pellets are probably also the product of a surficial deposit-feeding fauna tolerant of low dissolved oxygen levels such as polychaete worms. Silt pellets may record the chamber building activities of agglutinating foraminifera.

Surface features of sand grains from the Australian Continental Dunefield

Post-depositional features dominate the surfaces of sand grains from the Australian Continental Dunefield. Variations in the type and form of these features are evident among dunefields and also within individual desert regions. These variations are used to differentiate between sediment sources, and to provide evidence for the means of sediment transport into the deserts. Chemically precipitated features observed include previously unreported forms and are interpreted in terms of the environmental and climatic characteristics of the sand source regions. These forms here termed Type I sheet precipitation and Type II plate precipitation are believed to be intimately associated with the absence or presence respectively, of significant quantities of clay or clay pellets within the dune system. In the absence of clay the re-precipitation of silica from pore waters leads to the formation of Type I precipitated sheets. Type II plate precipitation results when grain surfaces covered by clay coatings are overlain by a secondary cover of Type I precipitated sheets. Such a cover would act as a resistant barrier to chemical attack and therefore protect the clay coatings from removal. Polygonal cracking found associated with Type II precipitation results from the dehydration of these underlying clay layers causing the disintegration of their silicate lattice structure. The predominance of chemically produced surface features and the poorly rounded and irregular nature of most grains indicate that the majority of sand in the Australian Continental Dunefield is currently stabilised and has not been transported long distances during its sedimentary history.

SEED PELLETING-HISTORY AND MODERN FUNDAMENTALS

The use and improvement of pelleted seed technology has greatly expanded in the last 15 years. Vegetable and flower seeds are pelleted to improve the singulation and planting placement in the field and greenhouse. Improved planting placement increases final-stand establishment, crop uniformity, and decreases seed and production costs. The commercial history of pelleted seed in the U.S. started after WWII with the development of the clay pellet by Filtrol Inc. Seed tablets and seed tape technologies were also developed but faded from the industry with the advent of better pelleted products. Current technology consists of a “splitting” seed pellet that allows for improved oxygenation. Improved technology also allows for pellet weights that can be tailored to meet the planting requirements of different species and planting systems.

Fundamental Study of the Thermal Desorption of Toluene from Montmorillonite Clay Particles

Nonisothermal desorption of toluene from individual montmorillonite clay particles was measured experimentally and modeled mathematically to elucidate details of the overall thermal desorption process. A single-particle reactor was used. It consisted of a porous, 2-6-mm clay pellet formed around a 0.05-mm diameter thermocouple in a 6- or 9-mm o.d. glass tube. The tube was surrounded by a supplementary heater and placed in a GC oven. Desorption rates were obtained as a function of heating rate, clay type, particle size, and purge gas flow rate. In addition, the adsorption isotherms for two toluene/clay systems and one n-dodecane/clay system were measured and correlated using the Freundlich isotherm. At the conditions examined, the rate-controlling mechanism is associated with intraparticle diffusion. Isothermal desorption experiments using clay pellets of different sizes demonstrate that local desorption kinetics are not rate-controlling. Toluene shows a slower desorption rate than n-dodecane at low concentrations. This is attributed to the hindered removal of toluene from interlamellar regions of the clay. 39 refs., 9 figs., 4 tabs.