Optimal operating parameters in the composting of swine manure with wastepaper

A series of experiments were conducted to determine the optimal conditions for composting of swine manure and wastepaper. The aeration rate and mixing ratio were the variables investigated. In the first study (Study-1), four experiments each with the same mixing ratio but a different aeration rate were carried out. In the second study (Study-2), different mixing ratios were investigated, each however with the same aeration rate which was found to be optimal from Study-1. Composting efficiencies were evaluated on the temperature profile and the reduction of C/N ratio. From the aeration rates of 200, 500, 1000, and 1500 mL/min.kg_vs that were evaluated, the aeration rate of 500 mL/min.kg_vs and higher showed good results. In Study-2, where the initial C/N ratios were 20, 25, 30, and 35 respectively, the C/N ratio of 30 was found to be optimal. In conclusion, the composting of swine manure with the amendment of wastepaper was best carried out at the aeration of > 500 mL/min.kg_vs and C/N ratio of 30.     

Adaptation of the CAS test system and synthetic sewage for biological nutrient removal. Part II: design and validation of test units

A global increase in biological nutrient removal (BNR) applications in wastewater treatment and concern for potential effects of anthropogenic substances on BNR processes resulted in the adaptation of the Continuous Activated Sludge (CAS) laboratory test system (cf. guideline OECD 303A or ISO 11733). In this paper two novel systems are compared to the standard CAS unit: the Behrotest KLD4 and a University of Cape Town system (CAS-UCT). Both are 'single sludge' systems with an anoxic/aerobic and an anaerobic/anoxic/aerobic configuration, respectively. They both can simulate the essential processes of full-scale BNR installations. The units where fed with a specially designed synthetic sewage, Syntho (cf. Part I of this study), or its precursor BSR3 medium. The performance of the two new units was benchmarked against the standard CAS system in terms of carbon/nitrogen/phosphorus (C/N/P) removal, as well as primary biodegradation of the surfactants linear alkylbenzene sulfonate (LAS) and glucose amide (GA). Both systems allow to easily achieve stable excess N- and P-removal. Experimental C/N/P removal data compared closely with simulations obtained with the IAWQ Activated Sludge Model No. 2 (ASM2), and with full scale BNR plants with a similar configuration. In both units the effluent concentrations of the surfactants tested were significantly reduced in comparison to the standard CAS system (up to 50% less). No adverse effects on BNR were noted for the test surfactants dosed at 400 microg/l together with an overall surfactant background concentration in the feed of ca. 20 mg/l. The proposed systems hold potential to complement the standard CAS system for situations where advanced sewage treatment plants with BNR need to be simulated in the laboratory with minimum effort.     

The ability of Azolla caroliniana to remove heavy metals (Hg(II), Cr(III), Cr(VI)) from municipal waste water

The aim of this paper was to investigate the capacity of a small water fern, Azolla caroliniana Willd. (Azollaceae), to purify waters polluted by Hg and Cr. Many plants are capable of accumulating heavy metals (called hyperaccumulators) and one of them is the water fern A. caroliniana. During 12 days of the experiment the fern was grown on the nutrient solution containing Hg2+, Cr3+ and CrO4(2-) ions, each in a concentration 0.1, 0.5 and 1.0 mg dm(-3). The presence of these ions caused a 20-31% inhibition of A. caroliniana growth, the highest in the presence of Hg(II) ions, in comparison to the control. After day 12 of the experiment, metal contents the solution decreased to 0-0.25 mg dm(-3), and this decrease comprised between 74 (Cr3+ 1.0 mg dm(-3) treatment) and 100% (CrO4(2-) 0.1 mg dm(-3) treatment). The fern took a lesser quantity of the metals from 0.1 mg dm(-3) treatments compared to 0.5 and 1.0 mg dm(-3) treatments. In the A. caroliniana tissues the concentration of heavy metals under investigation ranged from 71 to 964 mg kg(-1) dm; the highest level being found for Cr(III) containing nutrient solution.     

The role of ferrous ion in Fenton and photo-Fenton processes for the degradation of phenol

The efficiency of different Fenton-related oxidative processes such as Fenton, solar-Fenton and UV-Fenton were examined using phenol as a model compound in simulated and industrial wastewater. A batch study was conducted to optimize parameters like pH, hydrogen peroxide concentration and ferrous ion concentration governing the Fenton process. At optimum conditions, different Fenton-related processes were compared for the degradation of phenol. Increased degradation and mineralisation efficiency were observed in photo-Fenton processes as compared to conventional Fenton process. The maximum mineralising efficiency for phenol with Fenton, solar and UV-Fenton processes were 41%, 96% and 97% respectively. In Fenton process, carboxylic acids like acetic acid and oxalic acid were formed as end products during the degradation of phenol while in photo-Fenton processes, both these ions were identified during the early stages of phenol degradation and were oxidized almost completely at 120 min of the reaction time. In photo-Fenton processes (solar and UV light) complete degradation were observed with 0.4 mM of Fe2+ catalyst as compared to 0.8 mM of Fe2+ in conventional Fenton process. In Fenton and solar-Fenton processes, an iron reusability study was performed to minimize the amount of iron used in treatment process. The efficacy of Fenton and solar-Fenton processes was applied to effluent from phenol resin-manufacturing unit for the removal and mineralisation of phenol.     

Modelling the atmospheric fate and seasonality of polycyclic aromatic hydrocarbons in the UK

This paper presents the results from an exercise in atmospheric contaminant fate modelling, which had three main objectives: (1) to investigate the balance between estimated national atmospheric emissions of six selected PAHs and observed ambient measurements for the UK, as a means of testing the current emission estimates; (2) to investigate the potential influence of seasonally dependent environmental fate processes on the observed seasonality of air concentrations; and (3) after undertaking the first two objectives, to make inferences about the likely magnitude of seasonal differences in sources. When addressing objective 1 with annually averaged emissions data, it appeared that the UK PAH atmospheric emissions inventory was reasonably reliable for fluorene, fluoranthene, pyrene, benzo[a]pyrene and benzo[ghi]perylene--but not so for phenanthrene. However, more detailed analysis of the seasonality in environmental processes which may influence ambient levels, showed that the directions and/or magnitudes of the predicted seasonality did not coincide with field observations. This indicates either that our understanding of the environmental fate and behaviour of PAHs is still limited, and/or that there are uncertainties in the emissions inventories. It is suggested that better quantification of PAH sources is needed. For 3- and 4-ringed compounds, this should focus on those sources which increase with temperature, such as volatilisation from soil, water, vegetation and urban surfaces, and possible microbially-mediated formation mechanisms. The study also suggests that the contributions of inefficient, diffusive combustion processes (e.g. domestic coal/wood burning) may be underestimated as a source of the toxicologically significant higher molecular weight species in the winter. It is concluded that many signatory countries to the UNECE POPs protocol (which requires them to reduce national PAH emissions to 1990 levels) will experience difficulties in demonstrating compliance, because source inventories for 1990 and contemporary situations are clearly subject to major uncertainties.     

Soil functional responses to excess nitrogen inputs at global scale

There is little evidence that nitrogen (N) cycling in the highly weathered, low-phosphorus (P), acidic soils found in Southern Hemisphere continents will differ greatly from that in North America and Europe. Evidence from the 'south' shows: the similarity in forms and temporal patterns in losses of N from different land uses; that the C:N ratios of the forest floor/litter layer from different continents are strongly predictive of a range of processes on a global scale; that generalizations based on Northern Hemisphere experience of the impact of N additions to 'P-limited' ecosystems are likely to fail for southern ecosystems where anatomical and physiological adaptation of native plants to low-P soils makes questionable the concept of 'P-limitation'; that the greatest threats in the 'south' are probably changes in land use that may greatly increase N inputs and turnover; that localized increases in N inputs produce similar effects to those seen in the 'north'.     

Release of uranium from rock matrix--a record of glacial meltwater intrusions?

Uranium release observed in a rock matrix around water-carrying fractures was studied using U-series disequilibrium (USD) modelling and mass balance calculations. Several release scenarios were tested, with specific attention to the glacial aspects. The release appears to have occurred in two or three violent episodes during the last 300 ky. A release after the last glaciation can be excluded on mass flow grounds. Continuous release for more than 300 ky can be excluded on radioactive disequilibrium grounds. Repeated inflows of oxic glacial meltwater seem to have triggered the release episodes.     

An application of parametric and nonparametric models to the assessment of fluoride levels in vegetation exposed to stack emissions of an aluminum reduction plant in Greece

Various statistical models were developed for assessing airborne fluoride (F) levels in natural vegetation near an aluminum reduction plant using as predictor variables the distance from the emission source, the predominating wind, and characteristic topography-geomorphology parameters. Results revealed that F concentrations in vegetation showed a predictable response to both wind conditions and landscape features. The linear model was found to give good estimations, taking advantage of the relatively strong linear correlation between concentration and distance. A nonlinear relationship between the F concentration in vegetation and the other variables was also found, while interactions between the variables were found to be non-first-order. The nonlinear relationship hypothesis was supported by the improved results of various nonlinear models that also indicated the importance of the area's topography-geomorphology and meteorology in model predictions. The application of an artificial neural network (ANN) model showed the closest agreement between predicted and observed values with a correlation coefficient of 0.92. The improved reliability of the ANN and a regression tree model (RTM) also were indicated by the normal distribution of their residuals. The RTM and the ANN were further investigated and found to be capable of identifying the importance of the variables in vegetation exposure to air emissions.     

Genetic effects of air pollution on forest tree species of the Carpathian Mountains

The effects of air pollution on the genetic structure of Norway spruce, European silver fir and European beech were studied at four polluted sites in Slovakia, Romania and Czech Republic. In order to reduce potential effects of site heterogeneity on the health condition, pair-wise sampling of pollution-tolerant and sensitive trees was applied. Genotypes of sampled trees were determined at 21 isozyme gene loci of spruce, 18 loci of fir and 15 loci of beech. In comparison with Norway spruce, fewer genetic differences were revealed in beech and almost no differentiation between pollution-tolerant and sensitive trees was observed in fir. In adult stands of Norway spruce, sensitive trees exhibited higher genetic multiplicity and diversity. The decline of pollution-sensitive trees may result thus in a gradual genetic depletion of pollution-exposed populations of Norway spruce through the loss of less frequent alleles with potential adaptive significance to altered stressing regimes in the future. Comparison of the subsets of sensitive and tolerant Norway spruce individuals as determined by presence or absence of discolorations ("spruce yellowing") revealed different heterozygosity at 3 out of 11 polymorphic loci.     

Vegetation of the selected forest stands and land use in the Carpathian Mountains

Within the framework of the project "Effects of forest health on biodiversity with emphasis on air pollution in the Carpathian Mountains" 26 permanent study sites were established in the vicinity of the ozone monitoring sites. The study sites were located on the NW-SE transect through the Western (12 sites), Eastern (11 sites) and Southern (3 sites) Carpathians in forest ecosystems typical of each area. Some of the forest monitoring sites were located in national parks, biosphere reserves and areas of protected landscape. Each permanent site of 0.7 ha area consisted of 5 small 500m(2) circular plots, arranged in the form of a cross, i.e. four placed on the cardinal points (N, E, S, W) and one in the center. Phytosociological records were done twice during the 1998 growing season using the Braun-Blanquet's method. The study sites represented various types of forest: Picea abies stands (8), beech (Fagus sylvatica) stands (10), fir (Abies alba) stands (2) and mixed beech-fir, spruce-fir and beech-spruce stands (6). Age of most stands was 80-100 years. Degree of crown damage varied greatly between sites, a percentage of damaged trees decrease in Carpathians from West to East. It corresponds well with the O(3) level in these areas. Typical damage by O(3) in herb layer species in several Carpathian sites were found. Land-use map for the entire Carpathian Mountains and two detailed land use maps for Tatras (Western Carpathians) and Retezat (Southern Carpathians) are presented. A little more than half of the Carpathian territory is forested. The most densely forested are Eastern Carpathians, while the most sparsely Western Carpathians. Arable lands occupy 22.6% of the Carpathians, pastures and meadows 6.2%, water bodies 1.9%, and build up areas several percent. In the highest elevation of the Carpathians alpine meadows (11.3%) and rocks (3.5%) are distributed.