Full-scale phosphorus recovery from digested waste water sludge in Belgium - part I: technical achievements and challenges.

To date, phosphorus recovery as struvite in wastewater treatment plants has been mainly implemented on water phases resulting from dewatering processes of the sludge line. However, it is possible to recover struvite directly from sludge phases. Besides minimising the return loads of phosphorus from the sludge line to the water line, placing such a process within the sludge line is claimed to offer advantages such as a higher recovery potential, enhanced dewaterability of the treated sludge, and reduced speed of scaling in pipes and dewatering devices. In the wastewater treatment plant at Leuven (Belgium), a full-scale struvite recovery process from digested sludge has been tested for 1 year. Several monitoring campaigns and experiments provided indications of the efficiency of the process for recovery. The load of phosphorus from the sludge line returning to the water line as centrate accounted for 15% of the P-load of the plant in the reference situation. Data indicated that the process divides this phosphorus load by two. An improved dewaterability of 1.5% of dry solids content was achieved, provided a proper tuning of the installation. Quality analyses showed that the formed struvite was quite pure.

Derangement of composite filler distribution inside syringe-type delivery systems.

Used and almost emptied syringes of two brands of composites contained material close to the pestle-head that appeared to be more granular and dry, as compared to the composite obtained from unused syringes. The present results suggest that a derangement of filler and matrix phases occurred inside the used syringes when compared to unused controls. Stress imposed on the composite material inside the unused syringes resulted in a comparable derangement of filler and matrix phases. Although this derangement was limited, the effect could contribute to intra- and interlaboratory scattering of data.

Waste water analysis by purge and trap capillary GC-FTIR spectrometry.

Gas chromatography with Fourier transform infra-red spectroscopic detection (GC-FTIR) is used for the analysis of waste water samples. Compared to GC-MS, this technique offers a more complete identification of organic compounds. Lower concentrations of organic volatiles however require preconcentration techniques such as a Purge and Trap (P&T) preconcentrator. Using this combination, concentrations of organic volatiles in the ppb range can be detected and positively identified.

Cardiac rehabilitation: an overview.

This article provides an overview of the process and application of cardiac rehabilitation following myocardial infarction and coronary artery bypass grafting. The authors discuss risk factor modification targeting smoking, serum cholesterol, hypertension, and exercise training. The role of the physician and the practitioner are addressed as well as the physiological and psychological benefits of cardiac rehabilitation.