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Biomedical subjects

D L Jensen

Publications and source records attributed to D L Jensen.

11 recordsLinked to original sources
PubMed2003

On-site treatment and landfilling of MSWI air pollution control residues.

Air pollution control (APC) residues from municipal solid waste incineration (MSWI) are difficult to landfill due to substantial leaching of trace metals. An on-site pretreatment prior to landfilling of APC-residues was investigated in terms of bench-scale experiments with a semidry APC-residue and a fly ash. The treatment involved mixing of the residues with a ferrous sulphate solution and subsequent oxidation of the suspension. Afterwards, the suspension was spread on a dedicated landfill section and allowed to drain by gravity through the drainage system of the landfill. The wastewater from the process, collected through the drainage system, contained large concentrations of salts (Cl: 14-30 g/l, Na: 4-9 g/l, K: 5-11 g/l, Ca: 2-12 g/l) but low concentrations of trace metals (e.g. Pb: 14-100 microg/l, Cd: <2-7 microg/l). The treated residues left in the landfills were later subject to leaching by simulated rainfall. The leachate contained low concentrations of trace metals (Pb: <120 microg/l, Cd: <2 microg/l, Cr: <485 microg/l). The leachate concentrations from the treated APC-residues were substantially reduced compared to concentrations in leachate from untreated APC-residues. Particularly in the early stages of the leaching, concentrations of trace metals were reduced by up to four orders of magnitude.

Air Pollution↗
PubMed2002

Treatment of waste incinerator air-pollution-control residues with FeSO4: concept and product characterisation.

This paper describes a new concept for treatment of air pollution-control (APC) residues from waste incineration and characterises the wastewater and stabilised residues generated by the process. The process involves mixing of APC-residues with a ferrous sulphate solution and subsequent oxidation of the suspension (Ferrox-process 1996). The process results in a significant reduction in the leaching of salts and heavy metals from the residue, by washing out most of the salts and by binding the heavy metals in the iron oxides formed. In the laboratory, a semidry gas-cleaning residue and a fly ash were treated by the process. The generated wastewater contained low concentrations of heavy metals (e.g. Pb: 27-39 microg l(-1) and Cd: 2.6-4.6 microg l(-1)), but high concentrations of salts (e.g. Cl, Na, K, and Ca). The treatment process redUced the leaching of Pb from the residues by more than two orders of magnitude at fixed pH as determined by pH-static leaching tests. Likewise, the leaching of Cd, Zn and Cu was significantly reduced. The effect on elements that form oxyanions (e.g. Cr) is marginal and in the current process there is no reduction in the release of Hg.

Air Pollution↗
PubMed2002

Treatment of waste incinerator air-pollution-control residues with FeSO4: laboratory investigation of design parameters.

The key design parameters of a new process for treatment of air-pollution-control (APC) residues (the Ferrox-process) were investigated in the laboratory. The optimisation involved two different APC-residues from actual incinerator plants. The design parameters considered were: amount of iron oxide supplied, the liquid-to-solid ratio of the process, the separation of solids and wastewater, the sequence of material mixing, the possibilities of reuse of water, the feasibility of using secondary (brackish) water, and simple means to improve the wastewater quality. The investigation showed that an optimum process configuration could be obtained yielding a stabilised solid product with low leaching of heavy metals and a dischargable wastewater with high contents of salts (in order to remove salts from the solid product) and low concentrations of heavy metals. The amount of iron added to the APC-residues must be optimised for each residue. The overall water use can be limited to a L/S-ratio of 3 l kg(-1) including water used for washing of the treated products.

Air Pollution↗
PubMed2001

High temperature co-treatment of bottom ash and stabilized fly ashes from waste incineration.

Bottom ashes from two Danish municipal solid waste incineration plants were heated at 900 degrees C with iron oxide stabilized air pollution control residues at actual mass flow ratios (9:1), simulating a treating method for the residues. The two residues were co-treated, producing one combined stream that may be utilized as a secondary road construction material. Scanning electron microscope analysis and grain size distribution analysis indicated that sintering of the particles did not occur. Batch leaching tests at liquid/solid 10 l/kg at a range of pH-values (6-10) quantified with respect to Cd, Cr and Pb revealed significant positive effects of co-heating the ashes, although Pb showed slightly increased leaching. At a liquid/solid ratio of 10 l/kg the leachate concentrations were still low at pH 7-10 and the release of Pb was, thus, not expected to limit the utilization of the mixed ashes. The process, thus, fixates the metals in the solid residues without altering the leaching properties of the bottom ash too significantly.

Air Pollution↗
PubMed1981

Total and differential cell counts in secretions of the nonlactating bovine mammary gland.

Total cell counts and differential patterns in secretion of 52 mammary quarters of 23 Holstein-Friesian cows were determined at intervals in the early dry and the pre- and postpartum periods. Each sample was cultured to determine infection status of the gland. Twelve quarters remained noninfected, and 10 quarters were infected throughout the test period. Patterns of bacterial isolation from the remaining 30 quarters indicated that transient or intermittent infections had occurred. In secretions of noninfected quarters, geometric mean cell counts increased from 3.6 x 10(5) cells/ml on the last day of lactation to 1.8 x 10(7) cells/ml by the 7th day of the dry period. Total cell concentration remained high through most of the dry period; counts decreased in the prepartum period and reached a level of 2.8 x 10(5)/ml by the 6th day after parturition. Macrophages were the predominant cell type through most of the dry period. The proportion of neutrophils was high initially, decreased as the dry period progressed, and tended to increase as parturition approached, whereas that of lymphocytes increased during involution and then decreased near parturition. In secretions from persistently infected quarters, concentrations of total cells, neutrophils, macrophages, and lymphocytes were higher at all sampling times than in secretions from noninfected quarters. Neutrophils were the predominant cell type in infected secretions at all sampling times. Peak cell concentrations of 8.5 x 10(7)/ml in infected quarters were reached in the immediate prepartum period.

Animals↗
PubMed1975

Macrophages in bovine milk.

The high vacuolated mononuclear cells in milk from normal bovine mammary glands, usually designated epithelial cells, were examined for properties characteristic of macrophages. In vitro, these cells concentrated neutral red into cytoplasmic vacuoles, adhered rapidly to and spread on glass, and phagocytosed viable Streptococcus agalactiae and Staphylococcus aureus. Neutral red uptake was demonstrated in vivo, and the vacuolated mononuclear cells phagocytosed formalinkilled S aureus in vivo. These results suggest that these cells are macrophages.

Animals↗