Diversion from landfill: quality products from valuable plastics

Mechanical recycling of 100% post-consumer plastic waste into high-quality products has been performed. The chemical and physical properties of these recycled materials have been compared with similar products manufactured from virgin resins. The properties of a blow-moulded bottle prepared from 100% post-consumer high-density polyethylene (HDPE) showed that this recycled polymer exceeded the materials specifications for virgin plastic designs. Similarly, a sample of thermoplastic polyolefin (TPO, 100% polypropylene), obtained entirely from shredder residue (SR) displayed sufficient material strength for future separation and reprocessing.     

Trace Gas Emissions from Biomass Burning from Northeast Region in India—Estimates from Satellite Remote Sensing Data and GIS

Biomass burning associated with shifting cultivation areas from the northeastern region of India is an important source of trace gas emissions in the Southeast Asian region. In the present study, satellite data pertaining to IRS-P4 OCM data and DMSP-OLS has been used to quantify the intensity, areal extent and amount of biomass burnt in the northeastern region states at district level. Trace gas emissions have been quantified both by using IPCC based emission ratios and ground based emission ratios obtained from field based studies. Areal estimates with respect to shifting cultivation areas from IRS-P4 OCM satellite data of 4th April 2000 suggested nearly 112.99 km² of the northeastern region of India affected due to shifting cultivation. In the study, DMSP OLS nighttime data has been used to capture the real time fires during the dry season. The results suggested high amount of fires during the March season when compared to April and May. Using the emission ratios obtained from the ground-based studies and IPCC emission ratios, the emissions for the individual non-CO₂ trace gases have been computed in a GIS framework using the biomass data, combustion factors and emission ratios. Results suggested emissions of 2.063 Mt CH₄, 17.94 Mt CO, 1.419 Mt N₂O, and 51.28 Mt NO _x and 2.643 Mt release of CH₄, 3.7204 Mt CO, 0.145 Mt N₂O, and 8.477 Mt NO _x , respectively, from biomass burning due to shifting cultivation for the year 2000, from the northeastern region in India. The study highlights the importance of Satellite Remote sensing data and GIS in quantifying the trace gas emissions from biomass burning.     

Gaseous nitrogen and carbon losses from pig manure derived from different diets

Manipulation of the diets of pigs may alter the composition of the manure and thereby the environmental and agricultural qualities of the manure. Laboratory studies were performed to quantify the effect of manipulation of pig diets on the chemical composition of the derived manure (slurry), the potential emission of methane (CH4) and ammonia (NH3) during anaerobic storage of the manure, and the potential nitrous oxide (N2O) and carbon dioxide (CO2) emission after application of the manure to soil. The diets differed in contents of crude protein and salt (CaSO4), and the type and contents of nonstarch polysaccharides (NSP). Emissions of NH3 and CH4 during storage were smaller at a low than at a high dietary protein content. The emission of NH3 was significantly related to the contents of ammonium (NH4), total N, and pH. The emission of CH4 was significantly related to contents of dry matter, total C, and volatile fatty acids in the manure. The effect of manure composition on N2O emission markedly differed between the two tested soils, which points at interactions with soil properties such as the organic matter content. These types of interactions require soil-specific recommendations for mitigation of N2O emission from soil-applied pig manure by manipulation of the diet. From the tested diets, decreasing the protein content has the largest potential to simultaneously decrease NH3 and CH4 emissions during manure storage and N2O emission from soil. An integral assessment of the environmental and agricultural impact of handling and application of pig manure as a result of diet manipulation provides opportunities for farmers to maximize the value of manures as fertilizer and soil conditioner and to minimize N and C emissions to the environment.     

Shielding from ELF Magnetic Fields Emanating from Power Plants in Large Facilities

Summary Large facilities frequently have internal power plants. High power transformers and low voltage cables associated with these plants generate low-frequency magnetic fields of large amplitude, which can be above allowed exposure levels. In order to shield against these magnetic fields large shields are used. These plates are finite and their shielding effectiveness is compromised due to their finite dimensions. This paper evaluates the shielding afforded by such a plate, as related to the geometry of the placement of the source and victim and the dimensions and structure of the shield plate.     

Hydrogen production from biomass

The ‘hydrogen economy’ has received considerable attention in academic, industrial and political contexts. There are opportunities for vast reductions in greenhouse gas emissions, increased energy security and greater overall efficiency. However, if hydrogen is to become a fundamental energy source for electrical power generation, as well as a transportation fuel, novel generation pathways will be necessary to meet the increase in demand. A promising means for generating hydrogen is the thermochemical conversion of biomass to a synthesis gas, composed of a mixture of hydrogen, carbon monoxide, carbon dioxide and methane. In order to manipulate the composition and maximise the hydrogen output, a calcium-based carbon dioxide sorbent can be utilised in situ. The removal of carbon dioxide alters the reaction chemistry to preferentially produce hydrogen. In this work we report on the characterisation of a likely Ca-based carbon dioxide sorbent and demonstrate the merits of hydrogen production from biomass, with in situ carbon dioxide capture, on the basis of a thermodynamic study. Using this model we show that hydrogen output from biomass gasification can be increased from 40%-vol to 80%-vol (dry basis) when a carbon dioxide sorbent is used.     

Removal of herbicides from liquid media by fungi isolated from a contaminated soil

Fungi were isolated from soil samples corresponding to pesticide-contaminated soil (CS) and noncontaminated soil (NCS) in the Annaba vicinity (Algeria) and identified. The number of isolates obtained from CS and NCS were 263 and 288, respectively. The most frequent species (Aspergillus fumigatus, A. niger, A. terreus, Absidia corymbifera, and Rhizopus microsporus var microsporus) were not sensitive to the pesticides. The growth of the genus Trichoderma was inhibited by the pesticides, while genera Absidia and Fusarium were stimulated. The 53 species isolated were assayed for their ability to remove metribuzin from liquid medium. Only Botrytis cinerea from NCS and Sordaria superba and Absidia fusca from CS removed more than 50% of the compound after 5 d. Metamitron was very resistant. Among the 21 species tested, only Alternaria solani (from NCS), Drechslera australiensis (from CS and NCS), and Absidia fusca (from CS) reduced the concentration in the medium more than 10% (10-16%). Twelve species were grown with linuron, seven of them were inefficient in removing this compound. The two strains of Sordaria macrospora yielded 22 to 25% depletion, while Botrytis cinerea depleted linuron almost completely. Among the 31 species assayed for their ability to eliminate metobromuron, Botrytis cinerea (from CS and NCS) depleted almost completely the chemical from the medium. Rhizopus oryzae and Absidia fusca from CS removed 40 and 47% of the compound, respectively. No systematic relationships were observed between the soil contamination and herbicide elimination capacities of soil fungi. Absidia fusca and Botrytis cinerea were particularly interesting for bioremediation purposes because they were able to transform efficiently three of the four compounds assayed.     

Glassceramics obtained from industrial waste

Large areas of Latvia are contaminated with industrial waste: metallurgical slag, fly-ash, etching refuse, peat, and coal ash as well as glass waste which often contain dangerous substances. From the environmental point of view this waste should be neutralised. As this waste also contains valuable chemical compounds, it can be considered as a raw material for the generation of new materials. One method of utilisation is to produce recycled materials — street plates, decorative tiles, or floor tiles. Dense sintered glassceramics with a water uptake of 0.34–3.23 wt.%, a final density of 2.93–3.05 g/cm³, and a bending strength of 80–96 MPa have been created from industrial waste. The mast chemically durable glassceramics contained clay additions. Thus, the material containing only waste had a durability (mass loss) of 3.02% in 0.1 N HCl, while the composition containing 30% clay addition had a durability of 0.2% in 0.1 N HCl.     

Biogas production from olive pomace

Biogas production from a slurry obtained by mixing finely ground olive pomace in water was investigated using anaerobic digesters of 1-l working volume at 37°C. A start-up culture was obtained from a local landfill area and was adopted to the slurry within 10 days at this temperature. The biogas generation rates were determined by varying the total solids (TS) concentration in the slurry and the hydraulic retention time (HRT) during semi-continuous digestion. The maximum rate was found to be 0.70 l of biogas per l of digester volume per day, corresponding to a HRT of 20 days and 10% TS with a yield of 0.08 l biogas per g chemical oxygen demand (COD) added to the digester. The methane content of the biogas was in the range of 75–80% for both batch and semi-continuous runs, the remainder being principally carbon dioxide.     

从反坝运动引发的思考

对目前地表水坝的固有缺陷引发的有关对地表水坝建设利与弊的讨论的现状进行了介绍,并对地表水坝引起的负面效应进行了分析。     

A view from the countryside

Guest Editorial

A view from the countryside     

A view from the periphery

The author describes his background and relationship to the behavioral geography revolution at Clark. Key events included the independent invention of ‘turf maps’, the Place Perception Project of Blaut, Stea and McCleary, and the synergy of an exceptional cluster of faculty and students. The influence of the revolution on the author's own research has resulted in a radical redirection of effort toward applied research on children's environmental behavior, geographic learning, and participatory design methods in particular.