Effect of flocculation pre-treatment on membrane nutrient recovery of digested chicken slurry: mitigating suspended solids and retaining nutrients

Use of membrane filtration is attracting increasing attention for nutrient recovery from anaerobically digested slurry. However, the challenge is to reduce membrane fouling by effective solids mitigation, while maintaining valuable nutrients. In this study, the effects of several flocculation pre-treatments using polyaluminium chloride, iron chloride, and flocculant aid at various dosages were investigated. The results showed significant improvement in membrane flux from 0.8 to 27.6 mL/m2/s due to solid migration (up to 75% removal). Significant loss of PO43−-P (99%) and humic acids (40–80%) was observed. However, the content of NH4+-N and indoleacetic acids was largely maintained in the treated slurry. Moreover, toxic metals were significantly removed through flocculation, making the final product risk-free of heavy metals for agricultural application

Investigation into the cause of spontaneous emulsification of a free steel droplet : validation of the chemical exchange pathway

Small Fe-based droplets have been heated to a molten phase suspended within a slag medium to replicate a partial environment within the basic oxygen furnace (BOF). The confocal scanning laser microscope (CSLM) has been used as a heating platform to interrogate the effect of impurities and their transfer across the metal/slag interface, on the emulsification of the droplet into the slag medium. The samples were then examined through X-ray computer tomography (XCT) giving the mapping of emulsion dispersion in 3D space, calculating the changing of interfacial area between the two materials, and changes of material volume due to material transfer between metal and slag. Null experiments to rule out thermal gradients being the cause of emulsification have been conducted as well as replication of the previously reported study by Assis et al.[1] which has given insights into the mechanism of emulsification. Finally chemical analysis was conducted to discover the transfer of oxygen to be the cause of emulsification, leading to a new study of a system with undergoing oxygen equilibration

Solid phase extraction of pesticide residues in water samples: DDT and its metabolites

Solid phase extraction (SPE) cartridge embedded with octadecyl C18 chain bounded to silica particles were used for the isolation and trace enrichment of pesticides from water samples collected from cotton, rice growing and municipal areas. The eluents were analyzed with high performance liquid chromatography (HPLC) using methanol (100%) as mobiles phase at different UV-Visible wavelengths. DDT and its metabolites were found in all areas but were not present in all samples. Concentration of pesticide residues varies from sample to sample and was in the range of 0.017-1.06 ng ml-1. Overall, recoveries ranged from 84%-91% for all target pesticides

Quantifying the Pathway and Predicting Spontaneous Emulsification during Material Exchange in a Two Phase Liquid System

Kinetic restriction of a thermodynamically favourable equilibrium is a common theme in materials processing. The interfacial instability in systems where rate of material exchange is far greater than the mass transfer through respective bulk phases is of specific interest when tracking the transient interfacial area, a parameter integral to short processing times for productivity streamlining in all manufacturing where interfacial reaction occurs. This is even more pertinent in high-temperature systems for energy and cost savings. Here the quantified physical pathway of interfacial area change due to material exchange in liquid metal-molten oxide systems is presented. In addition the predicted growth regime and emulsification behaviour in relation to interfacial tension as modelled using phase-field methodology is shown. The observed in-situ emulsification behaviour links quantitatively the geometry of perturbations as a validation method for the development of simulating the phenomena. Thus a method is presented to both predict and engineer the formation of micro emulsions to a desired specification

A Review of Ferroalloy Tapping Models

Tapping is an important furnace operation in the ferroalloy industry and poses a number of complex and coupled challenges of both practical and economical importance. Owing to the hazardous high-temperature conditions surrounding the tap hole, the application of various modeling techniques allows for development and acquisition of both scientific and engineering knowledge of the process through physical or numerical proxies. In this review, earlier work on modeling of ferroalloy tapping is summarized and main principles of the tapping process and multiphase interaction of slag and metal are discussed and summarized. The main focus is on drainage of slag and alloys, but some attention will also be given to metal loss, metal overflow and health, safety and environment. Our review shows that although considerable progress has been made in computational capability over the last decades, However, it is clear that research and development in the field of ferroalloy furnace tapping remains at a relatively nascent stage. The most progress up to date has happened in the area of so called reduced-order models. Such models are robust and simple, and may be easily fitted to process data from a particular operation in order to develop tailored solutions. Such models are more easily combined with software and instruments, ultimately enabling improved automation, process control and ultimately improved tapping consistency