Prospects in straw disintegration for biogas production

The pretreatment methods for enhancing biogas production from oat straw under study include hot maceration, steam explosion, and pressure shockwaves. The micropore area (9, 55, and 64 m² g^-1) inhibitor formations (0, 15, and 0 mL L^-1) as well as the overall methane yields (67, 179, and 255 CH₄ VS t^-1) were robustly analyzed. It was confirmed that the operating conditions of the steam explosion must be precisely tailored to the substrate. Furthermore, it was beneficial to prepend the hot maceration before the steam explosion and the pressure shockwaves. The second alternative may give increased methane yields (246 in comparison to 273 CH₄ VS t^-1); however, the application of pressure shockwaves still faces limitations for deployment on a commercial scale.     

人口变化及其对空间发展的影响——以德国为例

在分析人口变化如何影响德国的城镇和区域发展的基础上,探讨了在城市与区域规划中如何应对人口变化的主要结果--人口缩减和老龄化的。人口减少对二战以来东德和西德的区域发展有重要影响作用。但是,直到1990年两德统一以前,两德的城市与区域规划一直是建立在人口增长的假设之上。两德统一以后,人口缩减和老龄化对城市和农村发展起到了决定性作用。首先,研究了人口缩减和老龄化的起因和结果,由于人口变化在东德更为显著,因此以东德为例,进行实证分析。其次,重点讨论如何应对人口衰减和老龄化带来的问题。对于城市地区而言,可以采用两种模式--“紧缩式”和“穿孔式”,这两种方式都可以通过减少建筑面积和增加绿色空间或利用强度较小的土地类型来提高生活质量。对于农村地区而言,则需要采取更加严格的方式来应对人口减少和老龄化。一条可行的路径是通过撤销公共服务设施等方式,有计划地舍弃部分村庄,将村民在城镇中进行集中安置     

A protocol for the evaluation of genotoxicity in bile of carp (Cyprinus carpio) exposed to lake water treated with different disinfectants

A sensitive and rapid method to evaluate toxic and genotoxic properties of drinking water supplied from Lake Trasimeno (Umbria, Central Italy) was worked out analysing bile in Cyprinus carpio exposed for 20 d to lake water treated with 3 different disinfectants, sodium hypochlorite (NaClO), chlorine dioxide (ClO₂) and peracetic acid (PAA). Fish were sacrificed at 0, 10 and 20 d in order to investigate the time course of these endpoints. An aliquot of bile samples was fractionated by adsorption on C₁₈ silica cartridges and the genotoxic potential of whole bile and of bile fractions was evaluated by the single-cell microgel-electrophoresis (comet) assay on human colonic adenocarcinoma cells (Caco-2). Bile (both whole and fractionated) from specimens exposed to the three disinfectants always showed a genotoxic activity as compared to the control group. The results of this study provide evidence that all three disinfectants cause an increase in bile genotoxicity of chronically exposed fish.     

Organic pollutants in compost and digestate. Part 2. Polychlorinated dibenzo-p-dioxins, and -furans, dioxin-like polychlorinated biphenyls, brominated flame retardants, perfluorinated alkyl substances, pesticides, and other compounds

Compost and digestate are important recycling fertilizers and have beneficial effects on soil parameters. However, they can contain significant amounts of organic pollutants. Here, the first comprehensive data set on dibenzo-p-dioxins and -furans (PCDD/F), dioxin-like polychlorinated biphenyls (DL-PCB), brominated flame retardants, perfluorinated alkyl substances (PFAS), pesticides, phthalates, nonylphenol and chlorinated paraffins (CP) in source-separated compost and digestate from Switzerland is presented (n = 3-18). The median summation 17PCDD/F and summation 12DL-PCB concentrations were at 3.2 ng I-TEQ kg(-1)dry weight (dw) and 3.0 ng WHO-TEQ kg(-1)dw, respectively. Brominated diphenyl ether 209 (BDE 209) accounted for 72% of the total polyBDE content (10 microg kg(-1)dw). Hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) levels were at 100 and 0.51 microg kg(-1)dw, respectively. PFAS were identified for the first time in compost and digestate (median concentration 6.3 microg kg(-1)dw, summation 21compounds). Out of 269 pesticides analysed, 30 fungicides, 14 herbicides, eight insecticides and one acaricide were detected. Di-(2-ethylhexyl)phthalate (DEHP) median concentration accounted for 280 microg kg(-1)dw and nonylphenol was below the detection limit of 1 mg kg(-1)dw. The sum of short and medium chain CP was between 90 and 390 microg kg(-1)dw. The concentrations observed were at or above the levels found in background soils, which are the main recipient of compost and digestate. Where actually applied, compost can contribute considerably to the total input of organic pollutants to the soil. However, on a total Swiss agricultural area base, inputs seem to be limited.     

Einschätzung der Konzentrationsprofile polyzyklischer aromatischer Kohlenwasserstoffe (PAK) in Böden des Biosphärenreservates Spreewald

To work out background values, the information of concentration profiles of PAHs in soils of uncontaminated territories is indispensable. This investigation shows PAH concentrations of different soil samples like agricultural soils, grassland, forest and litter from the biosphere reserve in Spreewald, Germany. The mean values of the soil samples are about 460 μg Σ-PAK/kg d.m. A top value of 7.2 mg Σ-PAK/kg d.m. shows a sample of a flooded grassland area. The relation of the concentrations in the litter, forest, grassland and agricultural soil samples is about 5∶3∶2∶1. Compared to the other samples, the litter samples contain a higher amount of low molecular PAHs. Increasing distance to the former power plants Lübbenau and Vetschau (brown coal) lead to decreasing PAH contents in the soil samples of forests from 2190.9 after 4 km to 294.8 Σ-PAK/kg d.m. after 16 km. In comparison to results obtained in Nordrhein-Westfalen and Bayern, the PAH measurements indicate Spreewald to be an uncontaminated and rural area.     

Diversity of microflora in the gut and casts of tropical composting earthworms reared on different substrates

The diversity of fungi, bacteria, yeast, actinomycetes and protozoa were analysed in the gut and casts of Eudrilus eugeniae, Lampito mauritii, Eisenia fetida and Perionyx excavatus, both qualitatively and quantitatively as influenced by different feed substrates like clay loam soil, cowdung and pressmud. While actinomycetes (Streptomyces albus, S. somaliensis, Nocardia asteroides, N. caviae and Saccharomonosporia) were not digested by any of these species of worms, protozoa (Amoeba proteus, A. terricola, Paramecium trichium, Euglena viridis, E. orientalis, Vorticella picta and Trichomonas hominis) and yeast (Candida tropicalis, C. krusei C. albicans and Cryptococcus neoformans) were totally digested. Certain species of fungi (Saksenae vasiformis, Mucor plumbeus, Cladosporium carrionii, C. herbacium, Alternaria sp., Cunninghamella echinulata, Mycetia sterila, Syncephalostrum racemosum, Curvalaria lunata, C. geniculata and Geotrichum candidum) and bacteria (Pseudomonas aeruginosa, Bacterium antitratum, Mima polymorpha, Enterobacter aerogenes, E. cloacae, Proteus vulgaris, P. mirabilis, P. rettgeri, Escherichia coli, Staphylococus citreus, Bacillus subtilis, B. cereus, Enterococci and Micrococci) were completely digested. Certain other species were not digested fungi like Aspergillus fumigatus, A. flavus, A. ochraceous, Trichoderma koningii (except by Eeugeniae), Fusarium moniliforme (except by E. eugeniae) and Rhizopus sp., and bacteria like Klebsiella pneumoniae and Morganella morganii) and these were multiplied during the transit of the organic residues through the gut of worms. The microbial proliferation was more in the casts, due to the environment prevailing--rich in nutrient supply and large surface area available for growth and reproduction of the microbes that lead to enhanced microbial activity and humic acid contents in the casts.     

Development of novel environmental friendly polyurethane foams

To prepare materials with improved recycling capability, new flexible biodegradable polyurethane foams, in which non-degradable polyether polyol was partly substituted by the bio-polyols based on cellulose or starch derivatives were synthesized. The incorporation of bio-polyols into the foams’ structures as well as their influence on the foam thermal stability was assessed by Fourier-transformed infrared spectroscopy and thermogravimetric analysis analyses. The ecotoxicological aspects of the newly synthesized foams were investigated by extracting the samples using freshwater as a solvent followed by applying the microbiotest screening toxkit under trade name “Thamnotoxkit F?” with larvae of freshwater shrimps Thamnocephalus platyurus.     

Mesocosm-scale evaluation of faunal and microbial communities of aerated and unaerated leachfield soil

Aeration improves the capacity of leachfields to decontaminate and reduce the nutrient load of wastewater. To gain a better understanding of the effects of aeration, we examined the faunal and microbial communities of septic system leachfield soil (0-4 and 4-13 cm) using replicated (n = 3) mesocosms that were actively aerated (AIR) or unaerated (LEACH). Protozoa were 40 to 140 times more abundant in AIR than in LEACH soil. No nematodes were found in LEACH soil, whereas AIR soil contained 5 to 14 x 10(3) nematodes (all bacteriovores) kg(-1). Active microbial biomass was four to five times higher in AIR than LEACH soil. Proteobacteria and actinomycetes/sulfate-reducing bacteria constituted a higher proportion of the community in AIR soil, whereas anaerobic Gram-negative bacteria/firmicutes were more prominent in LEACH soil. Ratios of prokaryotic to eukaryotic phospholipid fatty acids (PLFAs) were higher in LEACH soil, as were membrane stress index values, whereas the starvation index was higher in AIR soil. Community-level physiological profiles showed that 29 and 30 different substrates were used for growth by LEACH and AIR soil microorganisms, respectively. The AIR soil had more microorganisms capable of growing on 10 substrates, whereas growth on two substrates was higher in LEACH soil. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis of 16S rRNA gene fragments revealed greater diversity of dominant phylotypes in AIR than LEACH soil, with communities separated by treatment. Aerated leachfield soil had a larger and more diverse faunal and microbial community than unaerated soil, possibly due to differences in the type and availability of electron acceptors.     

Application of an Environmental Decision Support System to a Water Quality Trading Program Affected by Surface Water Diversions

Environmental decision support systems (EDSSs) are an emerging tool used to integrate the evaluation of highly complex and interrelated physicochemical, biological, hydrological, social, and economic aspects of environmental problems. An EDSS approach is developed to address hot-spot concerns for a water quality trading program intended to implement the total maximum daily load (TMDL) for phosphorus in the Non-Tidal Passaic River Basin of New Jersey. Twenty-two wastewater treatment plants (WWTPs) spread throughout the watershed are considered the major sources of phosphorus loading to the river system. Periodic surface water diversions to a major reservoir from the confluence of two key tributaries alter the natural hydrology of the watershed and must be considered in the development of a trading framework that ensures protection of water quality. An EDSS is applied that enables the selection of a water quality trading framework that protects the watershed from phosphorus-induced hot spots. The EDSS employs Simon’s (1960) three stages of the decision-making process: intelligence, design, and choice. The identification of two potential hot spots and three diversion scenarios enables the delineation of three management areas for buying and selling of phosphorus credits among WWTPs. The result shows that the most conservative option entails consideration of two possible diversion scenarios, and trading between management areas is restricted accordingly. The method described here is believed to be the first application of an EDSS to a water quality trading program that explicitly accounts for surface water diversions.     

Anaerobic biodegradation of high strength 2-chlorophenol-containing synthetic wastewater in a fixed bed reactor

In this study the continuous treatment of 2-chlorophenol (2-CP) containing synthetic wastewater at increasing concentrations up to 2600 mg L-1 in an anaerobic fixed bed reactor was achieved. As a source of microorganisms municipal sewage sludge was acclimatised to maximally 50 mg L-1 2-CP by 3 successive feedings within 1.5 months. Then, an anaerobic fixed bed reactor was inoculated with this sludge and was operated for 318 d, during which the 2-CP influent concentration was stepwise increased from 50 to 2600 mg L-1 within 265 d. At a hydraulic retention time (HRT) of 2.2 d the 2-CP loading rate was 2 g L-1 d-1 and the average 2-CP removal rate was 0.87 g L-1 d-1, accounting for 73% removal. This is the highest 2-CP removal rate ever reported. The negative effect of a 2-CP loading rate of 1.36 g L-1 d-1 on 2-CP removal was reversible within 2 wk when lower loading conditions (e.g. 0.76 g 2-CP L-1 d-1) were re-established. The median chloride ion release per unit 2-CP degraded was 0.24, which was reasonably close to the theoretically expected value of 0.28. In a batch assay, carried out with relatively clear reactor effluent, the highest removal rate of 2-CP was 175 mg L-1 d-1. At the time of reactor termination on day 318, the 2-CP removal rate by the biofilm in the reactor was 0.61 g L-1 d-1, corresponding to a HRT of 3.4 d and a 2-CP loading rate of 0.76 g L-1 d-1. At these very stable conditions removal of COD was 84% and of 2-CP 81%