Search

For a more eco-friendly production of energy and chemicals (e.g. lactic acid), green biorefineries are implementing an environmentally conscious technique of using green biomass. To increase the amount of lactic acid in grass and rye silage, different ensiling treatments were conducted. Additionally, after separating the organic juice, the specific methane yield of the remaining solid residue of the ensiled material was determined. The amount of lactic acid was increased by 168.8 % (149.7 ± 20.9 g kg−1dry matter (DM)) through applying homofermentative lactic acid bacteria together with carbonated lime to the raw material grass. For rye, while having a stable silage, the highest increase in lactic acid was achieved by chopping the raw material to a theoretical length of cut of 1 mm. As a result, an increase of 46.3 % (57.5 ± 0.6 g kg−1DM) was attained. Taxonomic profiling by 16S amplicon sequencing revealed that the homofermentative species Lactobacillus plantarumwas the most dominant species on both substrates with highest lactic acid production rate, though its growth on rye led to unstable silage conditions with butyric acid producing Clostridia. The specific methane yields of the corresponding solid residues were determined to be 335.7 ± 7.2 lNkg−1organic dry matter (ODM) for grass and at 235.0 ± 2.6 lNkg−1ODM for rye.

This article deals with the digestion of energy crops in a two‐phase biogas process based on an anaerobic leach‐bed reactor combined with an anaerobic filter. The biogas process is a microbiological conversion of biomass into methane and carbon dioxide. This process is carried out by different microorganisms and can be divided into four steps which normally take place in only one digester. To be able to digest difficult energy crops by mono‐digestion and to meet the different needs of the several bacteria, which take part in the four‐step process of the methane production, the process was divided into two phases: (i) an anaerobic batch leach‐bed phase, where the leachate was produced and (ii) an anaerobic filter, where the organic fraction of the leachate was converted into biogas. Considering the results of the experiments, the two‐phase digestion of energy crops exhibited stable digestion behavior. No biological imbalance of the process, e.g.due to a sudden change of substrate, was detected either in the leach bed or in the anaerobic filter. Variation in suitability for two‐phase fermentation with an anaerobic batch leach‐bed reactor was observed for various substrates. The different substrates varied in their influence on acid formation and concentration as well as an influence on the course of the pH value.Therefore, an effect on the distribution of energy to the phases could be observed.

A life cycle assessment model with eight potential scenarios for the conversion of energy crops into biogas and bioethanol in Germany has been developed, in order to compare energetic output/input relationships and potential environmental effects of the different pathways. The model includes parameter from the literature as well as own data collected at laboratory and semi‐industrial scale trials. Corn silage and ripe triticale, both whole plants, were chosen as typical energy crops for the assessment. In addition, steam explosion as a pretreatment technique was examined. Biogas, as well as bioethanol combined with biogas, is potentially helpful to reduce the consumption of nonrenewable energy carriers and its greenhouse gas emission under the investigated scenarios and the scope set. A future task will be the development of differentiated and well‐adapted concepts on the basis of a decision on liquid or gaseous fuels versusstationary supply of thermal and electrical energy from biomass.

Abstract: Background: Many different techniques to treat rectal prolapse have been introduced. Laparoscopic resection rectopexy has been shown to entail benefits regarding both perioperative results and short-term outcome, whereas data for long-term outcome are scarce. Methods: Between 1993 and 2008, all laparoscopic resection rectopexies for rectal prolapse II° or III° were selected from a prospective laparoscopic colorectal surgery database. We analyzed demographic, perioperative, and follow-up results. We defined two periods (1993–2000 and 2001–2008) for comparison of data. Long-term follow-up was obtained by sending questionnaires to all patients. Evaluation included constipation, incontinence, and recurrence of prolapse. Results: Between January 1993 and November 2008, we performed 152 laparoscopic resection rectopexies for rectal prolapse. Median age was 64.1 years (±14.6). Conversion rate was 0.7% (1), mean operation time was 204 (±65.3) min, and was significantly shorter in the second period compared with the first (P < 0.0001). Mortality was 0.7% (n = 1). Complication rates were 4% (n = 6; major) and 19.2% (n = 29; minor), respectively. Mean length of hospital stay was 11.3 (±6.4) days and was significantly shorter in the second period compared with the first period (P < 0.0001). Mean time of follow-up was 47.7 (±41.6) months. Improvement or complete elimination of constipation was stated by 81.3% (65), and improvement or elimination of incontinence was stated by 67.3% (72). Overall recurrence rate was 11.1% (n = 10) with a rate of 5.6% (n = 5) for a 5-year period. Of those patients with previous perineal surgery for rectal prolapse, 53.8% (7/13) experienced recurrent prolapse after laparoscopic resection rectopexy in contrast to 3.9% (3/77) of patients without previous perineal prolapse surgery (P < 0.0001). Conclusions: Our data support the benefits of laparoscopic resection rectopexy for rectal prolapse regarding both perioperative results and long-term functional outcome. Preceding perineal or open abdominal operations have an impact on recurrence after laparoscopic resection rectopexy.

Influences on dust emissions from livestock operations are number, weight, and kind of animals and characteristics of the housing system. Differences between facilities cannot be explained solely by mechanistic input variables. The objective of this study was to characterize the main input variables for modeling emissions of particulate matter with a mass median diameter ≤10 μm (PM10) from swine facilities using a data‐based model. Investigations were performed in mechanically ventilated facilities for weaning, growing‐finishing, and sows in Italy and Germany. The measurements included inside and outside concentration of airborne PM10particles (scatter light photometry), ventilation rate (calibrated measuring fans), indoor air climate at a measuring frequency of 60 s, feeding times, and animal‐related data such as weight and animal activity. Dust concentration and emission were simulated using a dynamic transfer function. The results indicated that the average PM10emission rate was influenced considerably by housing system. The simulation of the PM10emission rate resulted in a mean percentage error per data set of 21 to 39%, whereas the average simulated and measured emission rate per data set differed by about 4 to 19%. High prediction errors occurred especially during situations in which the absolute level and spatial location of the measured activity peaks did not correspond with the measured dust peaks. Further recommendations of the study were to improve continuous and accurate measurements of input variables, such as the activity level in animal houses, and to optimize the amount of measuring days in relation to the model accuracy.

In contrast to ammonia few data about the emissions of CH4, N2O and CO2from animal houses are yet available. To be reliable, such data should derive from investigations meeting the following minimum requirements: (1) continuous measurement of ventilation rates and gas concentrations; (2) long-term experiments, to cover diurnal and seasonal effects; (3) use of extremely exact measuring equipment. A literature review has shown that reliable data about CH4emissions are basically only available for cattle housing systems. Data about N2O emissions from animal houses are lacking, because of the difficulties in measuring very low N2O concentrations. However, the results of existing investigations are not comparable and most of them do not meet the minimum requirements mentioned above. Our own experiments have been carried out for dairy cows in loose housing with natural ventilation. The amount of CH4originating from cows' digestion is about 223 g per livestock unit (1 LU = 500 kg live-weight) per day and varies between 200 and 250 g per LU per day. It mainly depends on the feed intake, which is positively related to animal size, growth rate and production. There is practically no influence of outside conditions on the emission rate. N2O was emitted at about 1.6 g per LU per day.