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Balance sheet for phosphorus in the UK.

A balance sheet for the inputs, uses and outputs of phosphorus in the UK economy has been drawn up. The major import is fertilizer, amounting to about 200 kt P per year. After fertilizers, the other imports (in kt P) are in animal feeds (63), detergents (38) and human food (14). The major outputs are sewage (50), animal excreta (26) and refuse (21); soil losses are about 20 kt. The flowpaths for phosphorus through humans, animals and plants are described. The discrepancy of about 210 kt P/yr is explained by the fact that the amount of phosphorus in the soil increases each year by almost as much as the amount of fertilizer phosphorus added. In view of UK dependence on this imported resource it is suggested that priority is given to work which might eventually have some practical application in preventing or reversing the immobilization of phosphorus in the soil.

Agriculture↗

Effect of job rotation on need for recovery, musculoskeletal complaints, and sick leave due to musculoskeletal complaints: a prospective study among refuse collectors.

BACKGROUND: Job rotation might be an effective preventive measure to reduce the prevalence of musculoskeletal complaints, although its effect has not been yet established. The aim of the present study is to evaluate the effect of job rotation in refuse collecting on need for recovery, prevalence of musculoskeletal complaints, and sick leave due to musculoskeletal complaints. METHODS: A 1-year prospective study among refuse collectors was performed, using standardized questionnaires. Job rotation was performed between collecting two-wheeled containers and driving a refuse truck. The experimental groups of rotating refuse collectors at t(0) and t(1) (group R-R) and non-rotating refuse collectors at t(0) and rotating refuse collectors at t(1) (group NR-R) were compared with a reference group of non-rotating refuse collectors at t(0) and t(1) (group NR-NR). RESULTS: The adjusted need for recovery of group R-R was marginally significantly lower than need for recovery of the reference group. Groups R-R and NR-R had a more than two times higher risk for complaints of the low back than the reference group. No other significant results were found. CONCLUSIONS: Job rotation seemed to coincide with a reduced need for recovery and was associated with an increased risk of low back complaints. No effects were found on sick leave due to musculoskeletal complaints. The results might be influenced by the healthy worker selection effect in the reference group and its inverse in the rotating groups.

Adult↗

Anaerobic degradation of solid material: importance of initiation centers for methanogenesis, mixing intensity, and 2D distributed model.

Batch anaerobic codigestion of municipal household solid waste (MHSW) and digested manure in mesophilic conditions was carried out. The different waste-to-biomass ratios and intensity of mixing were studied theoretically and experimentally. The experiments showed that when organic loading was high, intensive mixing resulted in acidification and failure of the process, while low mixing intensity was crucial for successful digestion. However, when loading was low, mixing intensity had no significant effect on the process. We hypothesized that mixing was preventing establishment of methanogenic zones in the reactor space. The methanogenic zones are important to withstand inhibition due to development of acids formed during acidogenesis. The 2D distributed models of symmetrical cylinder reactor are presented based on the hypothesis of the necessity of a minimum size of methanogenic zones that can propagate and establish a good methanogenic environment. The model showed that at high organic loading rate spatial separation of the initial methanogenic centers from active acidogenic areas is the key factor for efficient conversion of solids to methane. The initial level of methanogenic biomass in the initiation centers is a critical factor for the survival of these centers. At low mixing, most of the initiation methanogenic centers survive and expand over the reactor volume. However, at vigorous mixing the initial methanogenic centers are reduced in size, averaged over the reactor volume, and finally dissipate. Using fluorescence in situ hybridization, large irregular cocci of microorganisms were observed in the case with minimal mixing, while in the case with high stirring mainly dead cells were found.

Acids↗

Determination of polynuclear aromatic compounds in composted municipal refuse and compost-amended soils by a simple clean-up procedure.

A rapid and reproducible procedure suitable for the analysis of polycyclic aromatic compounds (PACs) in sludges and soil samples has been developed. The PACs are isolated by ultrasonic extraction with methyl chloride, redissolution of the crude extract in isooctane and clean-up of the PAC-containing fraction by chromatography on alumina micro-columns. After separation and quantitative determination of the various PACs by capillary gas chromatography/mass spectrometry, more than 50 PAC compounds which cover a wide range of concentrations were detected in the sludge samples. The most abundant compounds were mono-, di- and trimethyl derivatives of naphthalene, phenanthrene, fluorene, dibenzethiophene and naphthothiophene. No accumulation of PAC in an agricultural soil after an experiment of compost application over three years was observed.

Fatty Acids↗

Phenotypic characterization of food waste degrading Bacillus strains isolated from aerobic bioreactors.

A phenotypic characterization of seventeen Bacillus strains isolated from aerobic thermophilic bioreactors of a food waste processing company was carried out, using fatty acid and enzymatic activity profiles. It was observed that each species possessed a typical fatty acid and enzymatic production profile. Bacillus licheniformis strains exhibited the most significant enzyme production. Numerical analyses (principal component and hierarchical cluster analyses) revealed that Bacillus licheniformis strains were homogeneous regarding their fatty acid profiles whilst B. subtilis and Bacillus pumilus strains showed some phenotypic differences. However, enzymatic activities numerical analyses indicated that these three Bacillus species were more homogeneous regarding this phenotypic characteristic.

Aerobiosis↗

Epidemiology of human rotaviruses in a maternity unit as studied by electrophoresis of genomic RNA.

An epidemiological survey of Rotavirus infections in a maternity unit was carried out between May 1983 and August 1984. Rotaviruses have been detected throughout the survey in 184 of 528 fecal samples obtained from 3 and 6 day-old newborns. Rotavirus excretion could be detected neither from the mothers nor from the medical attendants. Rotavirus RNA was analyzed by polyacrylamide gel electrophoresis. All the strains isolated exhibited the same electropherotype. This result contrasts with the genomic variability amongst Rotavirus strains usually observed in pediatric wards, and is in agreement with some other studies conducted in maternity wards; in these locations Rotavirus infection seems to have a special epidemic status as compared with other communities.

Adult↗

Source separation, selective collection and in reactor digestion of biowaste.

Biowaste or the organic fraction of domestic waste, for instance kitchen, fruit and garden waste, is collected selectively in several European communities. The complementary fraction is called the dry or non recyclable fraction. A Dutch study reported that 92% of the participants that have a weekly collection service of both fractions (biowaste and non recyclable fraction) and 80% of the participants in the alternating collection program (one week biowaste and the next week non recyclable fraction) are pleased with separate collection of biowaste. Dominating problems that arise in case of alternating collection are a repulsive odor and an infestation with flies and maggots. By expanding the definition of biowaste to include non recyclable or soiled paper like dirty newspapers, table napkins and paper handkerchiefs, most of these problems can be overcome without changing the way compostable waste is collected and processed. The expanded definition of biowaste was used in this paper. Over a 12 month period a quality survey of the collected biowaste was conducted by the composting facility Intercompost, Hoeselt, Belgium. A special aspect was the fact that in one participating community baby diapers were included in the soiled paper fraction; this is called "biowaste+". The biowaste+ had a 10% non recyclable paper fraction opposed to only 1-2% of non recyclable paper present in the conventional biowaste. Baby diapers were a rather notable part (more than 80%) of this non recyclable paper fraction of biowaste+ and as a consequence might contribute to a large extent to improve the collection and treatment of biowaste. It was demonstrated that rural districts yielded about 35% more biowaste than more urban districts; resp. +/- 122 kg biowaste/capita. year versus +/- 90 kg biowaste/capita. year. In Hoeselt the biowaste+ yield was about 130 kg/capita.year. Biowaste+ is also separately collected in another Belgium community, namely Brecht. The purity level of the biowaste+ and the amount of non recyclable paper (including diapers) were comparable with the results of Hoeselt. In Hoeselt the biowaste+ fraction is composted aerobically. In Brecht on the other hand, the biowaste+ is processed using the Dry Anaerobic Composting process (DRANCO). The latter process is discussed in more detail. The biological start-up of the dry anaerobic composting installation at Brecht, Belgium, is reported. The reactor has a total volume of 808 m3 and a design capacity of 730 m3. After 2 months of start up, the fermentor was at full loading rate, i.e. 8 kg bVS/m3 reactor.day and the installation was working at full capacity, i.e. 40 ton/day.(ABSTRACT TRUNCATED AT 400 WORDS)

Bacteria↗

Analytical determination of the microbial utilization and transformation of humic acids extracted from municipal refuse.

Humic substances are usually the refractory part of natural organic matter, and in a landfill they can retain inorganic and organic micropollutants. This study has investigated analytically whether humic acids (HA) extracted by use of alkali from either fresh municipal refuse or from refuse disposed of in a landfill for up to 12 months can resist microbial degradation under aerobic conditions. When added as a supplementary nutrient source, up to 63.6% of HA was utilized and this percentage was enhanced to a mean value of 88.5% when different HA preparations were used as the sole source of carbon. In cultures of a soil microbial community containing the same preparations as sole sources of nitrogen, HA was usually completely utilized. The remaining HA re-isolated from some microbial cultures were highly depleted in carbon and, simultaneously, the nitrogen content was enhanced. The FTIR spectra were indicative of strong participation of aliphatic structural units in the refuse-related HA preparations. Because of the microbial activity, different carbonaceous substances were primarily removed from the HA structure, and an increase in nitrogenous molecular groups became apparent. The structural transformations brought about by soil microorganisms "in vitro" corresponded to those occurring naturally in HA obtained from refuse aged for 12 months in a landfill.

Bacteria↗