Drum granulation of NPK fertilizers

Nitrate-based NPK fertilizer was granulated in a bench scale drum granulation unit. The initial fertilizer possessed a particle size distribution similar to those in industrial granulation units. In this work, three factors are identified affecting the degree of fertilizer granulation, these are solution to solid phase ratio, the binder viscosity and the optimal rotation speed of the drum. Experimental results indicate that a critical solution to solid phase ratio is required for an increase in granulation in terms of mass median diameter. The saturated solution viscosity in this system was measured and correlated well to binder viscosity granulation theory with the critical Stokes number calculated at 700. The optimum rotation speed for flighted and unflighted drums correlated with the Froude number relationship for full scale granulation units. (C) 2000 Elsevier Science S.A. All rights reserved.

Like a rolling stone: the mobility of maerl (Corallinaceae) and the neutrality of the associated assemblages

Beds of nonattached coralline algae (maerl or rhodoliths) are widespread and considered relatively species rich. This habitat is generally found in areas where there is chronic physical disturbance such that maerl thalli are frequently moved. Little is known, however, about how natural disturbance regimes affect the species associated with maerl. This study compared the richness, animal abundance, and algal biomass of maerl-associated species over a two-year period in a wave-disturbed bed and a sheltered maerl bed. Changes in associated species over time were assessed for departures from a neutral model in which the dissimilarity between samples reflects random sampling from a common species pool. Algal biomass and species richness at the wave-exposed site and on stabilized maerl at the sheltered site were reduced at times of higher wind speeds. The changes in species richness were not distinguishable from a neutral model, implying that algal species were added at random to the assemblage as the level of disturbance lessened. Results for animal species were more mixed. Although mobile species were less abundant during windy periods at the exposed site, both neutral and non-neutral patterns were evident in the assemblages. Artificial stabilization of maerl had inconsistent effects on the richness of animals but always resulted in more attached algal species. While the results show that the response of a community to disturbance can be neutral, the domain of neutral changes in communities may be relatively small. Alongside non-neutral responses to natural disturbance, artificial stabilization always resulted in an assemblage that was more distinct than would be expected under random sampling from a common pool. Community responses to stabilization treatments did not consistently follow the predictions of the dynamic equilibrium model, the intermediate disturbance model, or a facilitation model. These inconsistencies may reflect site-specific variation in both the disturbance regime and the adjacent habitats that provide source populations for many of the species found associated with maerl.

Assessment of rolling resistance models in discrete element simulations

Particulate systems are of interest in many disciplines. They are often investigated using the discrete element method because of its capability to investigate particulate systems at the individual particle scale. To model the interaction between two particles and between a particle and a boundary, conventional discrete element models use springs and dampers in both the normal and tangential directions. The significance of particle rotation has been highlighted in both numerical studies and physical experiments. Several researchers have attempted to incorporate a rotational torque to account for the rolling resistance or rolling friction by developing different models. This paper presents a review of the commonly used models for rolling resistance and proposes a more general model. These models are classified into four categories according to their key characteristics. The robustness of these models in reproducing rolling resistance effects arising from different physical situations was assessed by using several benchmarking test cases. The proposed model can be seen to be more general and suitable for modelling problems involving both dynamic and pseudo-static regimes. An example simulation of the formation of a 2D sandpile is also shown. For simplicity, all formulations and examples are presented in 2D form, though the general conclusions are also applicable to 3D systems.

From ideal reactor concepts to reality:The novel drum reactor for photocatalytic wastewater treatment

This article reports the development of a novel drum photocatalytic reactor for treating dye effluent streams. The parameters for operation including drum rotation speed, light source distance, catalyst loading and H2O2 doping have been investigated using methylene blue as a model pollutant. Effluent can be generated by a number of domestic and industrial sources, including pharmaceutical, oil and gas, agricultural, food and chemical sectors. The work reported here proposes the application of semiconductor photocatalysis as a final polishing step for the removal of hydrocarbons from effluents sources, initial studies have proved effective in removing residual hydrocarbons from the effluent.

Remediation of oily wastewater from an interceptor tank using a novel photocatalytic drum reactor

A novel photocatalytic reactor has been developed to remediate oily wastewaters. In the first instance degradation rates of model organic compounds, methylene blue (MB) and 4-c hlorophenol (4-CP) were determined. The experimental set-up investigated a 1:10 w/v catalyst to organic solution volume, 30 g catalyst, 300 mls MB (10 μM) or 4-CP (100 μM). The catalyst investigated was a pellet catalyst to improve separation of the remediated volume from the catalyst following treatment. MB concentration decreased by 93% after 15 mins irradiation whilst 4-CP concentration decreased by 94% following 90 mins irradiation. Oily waste water (OWW) from an interceptor tank typically containing diesel oils was obtained from Sureclean, an environmental clean-up company. The OWW was treated using the same conditions as MB and 4-CP, the model organic compounds. Levels of total organic carbon (TOC) and total petroleum hydrocarbon (TPH) were used to monitor the efficacy of the photocatalytic reactor. TOC reduced by 45% following two 90 mins treatment cycles. TPH reduced by 45% following 90 mins irradiation and by a further 25% during a second stage of treatment. This reactor can be used as a polishing technique assembled within a wastewater treatment plant. Allowing for more than one pass through the reactor improves its efficiency. 

Arise My People to the Beating of the Drum

This is an essay including annotated critical editions documenting the history of reception of this song since 1848. Published in the Liederlexikon for the AHRC and DFG funded project 'The History of Reception of the Songs of the 1848 Revolution' (2009-2013).