REDUCTION OF FAECAL MICROBIOLOGICAL INDICATORS IN DIFFERENT COMPOST TOILETS

Large variations in numbers of faecal indicator bacteria were found irrespective of the storage time of collected human faeces. Little heat seemed generated from composting processes when bin units were stored locally in households. The low reduction in microbiological parameters and very limited temperature increase were generally corroborated by the results obtained in experiment 2 when pathogen indicators were added to thoroughly mixed faecal matter. Even though Salmonella died of rapidly the other faecal bacterial indicators survived in large numbers. We conclude, that the collection and storage of human faeces in the closed plastic bins studied here is associated with only little temperature increase and subsequent reduction in faecal bacterial indicators and pathogens. Thus, the bin units do not seem especially suitable for composting and hygienisation of human faece

LATRINE COMPOSTING – A HYGIENIC EVALUATION

Thermophilic composting of faecal matter from urine diverting toilets can effectively reduce the numbers of faecal bacterial indicators and pathogen. Already at 50C, the numbers of pathogens, including the Salmonella phage, and indicator organisms analysed were effectively reduced within a few days of exposure. Although the numbers of enterococci were reduced, they were continuous isolated as purple colonies on Slanetz and Bartleys agar after prolonged exposure at all temperature levels studied. This indicates that certain micro-organisms present in the composted faecal material, Enterococcus spp. or micro-organisms resembling enterococci on the agar medium, can survive and multiply even at 60C. These findings question the use of enterococci as faecal indicators and test organisms to control the efficiency of composting of human faeces. Further work is in progress to identify the taxonomy of these organisms

OVERLEVELSE AF INDIKATORORGANISMER OG SMITSTOFFER I KOMPOSTTOILETTER OG VED SIMULERET CENTRALISERET EFTERKOMPOSTERING AF AFFØRING FRA MENNESKER

Som resultat af projekterne kan drages følgende hovedkonklusioner om kompostering af fæces fra mennesker: Fæces fra de undersøgte typer af kompostbeholdere bør ikke anvendes til jordbrugsformål uden viderebehandling, da dette skønnes at være behæftet med hygiejne- og sundhedsrisici. Det skyldes, at der ikke blev dokumenteret egentlige termofile temperaturstigninger i fæcesmaterialet i komposttoiletenhederne i Hjortshøj, Dyssekilde og Sverige, og at fækale indikatorbakteriers antal varierede voldsomt, og der ingen entydig tendens var til forekomst af lavere kimtal ved lange opbevaringstider af de opsamlede fækalier

Asteroseismic diagrams for solar-type stars

We explore the feasibility of applying the Christensen-Dalsgaard diagram to real asteroseismic data and provide quantitative measures of the uncertainty associated with the results. We also propose a new kind of seismic diagram, based on the determination of the locations of sharp acoustic features inside a star. We show that by combining the information about the position of the base of the convective envelope or the HeII ionisation zone with a measure of the average large separation, it is possible to constrain the unknown chemical composition or the various parameters characterising the physical processes in the stellar interior. We demonstrate the application of this technique to the analysis of mock data for a CoRoT target star.Comment: Accepted for publication in A&

Dipolar modes in luminous red giants

Lots of information on solar-like oscillations in red giants has been obtained thanks to observations with CoRoT and Kepler space telescopes. Data on dipolar modes appear most interesting. We study properties of dipolar oscillations in luminous red giants to explain mechanism of mode trapping in the convective envelope and to assess what may be learned from the new data. Equations for adiabatic oscillations are solved by numerical integration down to the bottom of convective envelope, where the boundary condition is applied. The condition is based on asymptotic decomposition of the fourth order system into components describing a running wave and a uniform shift of radiative core. If the luminosity of a red giant is sufficiently high, for instance at M = 2 Msun greater than about 100 Lsun, the dipolar modes become effectively trapped in the acoustic cavity, which covers the outer part of convective envelope. Energy loss caused by gravity wave emission at the envelope base is a secondary or negligible source of damping. Frequencies are insensitive to structure of the deep interior.Comment: 10 pages, 7 figures, accepted for publication in Astronomy and Astrophysic

Seismic study of stellar convective cores

It has been shown that a discontinuity in the derivatives of the sound speed at the edge of the convective regions inside a star gives rise to a characteristic oscillatory signal in the frequencies of stellar oscillations. This oscillatory signal has been suggested as a means to study the base of the outer convection zone in low mass stars and possibly the outer edge of the convective core in high mass stars. Using stellar models we show that because of a phenomenon similar to aliasing in Fourier transform, it may not be possible to use this signal to detect the convective core. Nevertheless, it may be possible to determine the size of convective cores using the frequency separation \nu_{n+1,l}-\nu_{n,l}.Comment: Accepted for publication in A &

Escherichia coli contamination and health aspects of soil and tomatoes (Solanum lycopersicum L.) subsurface drip irrigated with on-site treated domestic wastewater.

Faecal contamination of soil and tomatoes irrigated by sprinkler as well as surface and subsurface drip irrigation with treated domestic wastewater were compared in 2007 and 2008 at experimental sites in Crete and Italy. Wastewater was treated by Membrane Bio Reactor (MBR) technology, gravel filtration or UV-treatment before used for irrigation. Irrigation water, soil and tomato samples were collected during two cropping seasons and enumerated for the faecal indicator bacterium Escherichia coli and helminth eggs. The study found elevated levels of E. coli in irrigation water (mean: Italy 1753 cell forming unit (cfu) per 100 ml and Crete 488 cfu per 100 ml) and low concentrations of E. coli in soil (mean: Italy 95 cfu g(-1) and Crete 33 cfu g(-1)). Only two out of 84 tomato samples in Crete contained E. coli (mean: 2700 cfu g(-1)) while tomatoes from Italy were free of E. coli. No helminth eggs were found in the irrigation water or on the tomatoes from Crete. Two tomato samples out of 36 from Italy were contaminated by helminth eggs (mean: 0.18 eggs g(-1)) and had been irrigated with treated wastewater and tap water, respectively. Pulsed Field Gel Electrophoresis DNA fingerprints of E. coli collected during 2008 showed no identical pattern between water and soil isolates which indicates contribution from other environmental sources with E. coli, e.g. wildlife. A quantitative microbial risk assessment (QMRA) model with Monte Carlo simulations adopted by the World Health Organization (WHO) found the use of tap water and treated wastewater to be associated with risks that exceed permissible limits as proposed by the WHO (1.0 × 10(-3) disease risk per person per year) for the accidental ingestion of irrigated soil by farmers (Crete: 0.67 pppy and Italy: 1.0 pppy). The QMRA found that the consumption of tomatoes in Italy was deemed to be safe while permissible limits were exceeded in Crete (1.0 pppy). Overall the quality of tomatoes was safe for human consumption since the disease risk found on Crete was based on only two contaminated tomato samples. It is a fundamental limitation of the WHO QMRA model that it is not based on actual pathogen numbers, but rather on numbers of E. coli converted to estimated pathogen numbers, since it is widely accepted that there is poor correlation between E. coli and viral and parasite pathogens. Our findings also stress the importance of the external environment, typically wildlife, as sources of faecal contamination

A Stellar Model-fitting Pipeline for Solar-like Oscillations

Over the past two decades, helioseismology has revolutionized our understanding of the interior structure and dynamics of the Sun. Asteroseismology will soon place this knowledge into a broader context by providing structural data for hundreds of Sun-like stars. Solar-like oscillations have already been detected from the ground in several stars, and NASA's Kepler mission is poised to unleash a flood of stellar pulsation data. Deriving reliable asteroseismic information from these observations demands a significant improvement in our analysis methods. We report the initial results of our efforts to develop an objective stellar model-fitting pipeline for asteroseismic data. The cornerstone of our automated approach is an optimization method using a parallel genetic algorithm. We describe the details of the pipeline and we present the initial application to Sun-as-a-star data, yielding an optimal model that accurately reproduces the known solar properties.Comment: 5 pages, 2 figs, Stellar Pulsation: Challenges for Theory and Observation (proceedings to be published by AIP