Application of artificial neural network in medical geochemistry

For the evaluation of various adverse health effects of chemical elements occurring in the environment on humans, the comparison and linking of geochemical data (chemical composition of groundwater, soils, and dusts) with data on health status of population (so-called health indicators) play a key role. Geochemical and health data are predominantly nonlinear, and the use of standard statistical methods can lead to wrong conclusions. For linking such data, we find appropriate the use method of artificial neural networks (ANNs) which enable to eliminate data inhomogeneity and also potential data errors. Through method of ANNs, we are able to determine the order of influence of chemical elements on health indicators as well as to define limit values for the influential elements at which the health status of population is the most favourable (i.e. the lowest mortality, the highest life expectancy). For determination of dependence between the groundwater contents of chemical elements and health indicators, we recommend to create 200 ANNs. In further calculations performed for identification of order of influence of chemical elements as well as definition of limit values, we propose to work with median or mean values from calculated 200 ANNs. The ANN represents an appropriate method to be used for environmental and health data analysis in medical geochemistry.     

Chromium in soil layers and plants on closed landfill site after landfill leachate application

Landfill leachate (LL) usually contains low concentrations of heavy metals due to the anaerobic conditions in the methanogenic landfill body after degradation of easily degradable organic matter and the neutral pH of LL, which prevents mobilization and leaching of metals. Low average concentrations of metals were also confirmed in our extensive study on the rehabilitation of an old landfill site with vegetative landfill cover and LL recirculation after its treatment in constructed wetland. The only exception was chromium (Cr). Its concentrations in LL ranged between 0.10 and 2.75 mg/L, and were higher than the concentrations usually found in the literature. The objectives of the study were: (1) to understand why Cr is high in LL and (2) to understand the fate and transport of Cr in soil and vegetation of landfill cover due to known Cr toxicity to plants. The total concentration of Cr in LL, total and exchangeable concentrations of Cr in landfill soil cover and Cr content in the plant material were extensively monitored from May 2004 to September 2006. By obtained data on Cr concentration in different landfill constituents, supported with the data on the amount of loaded leachate, amount of precipitation and potential evapotranspiration (ETP) during the performance of the research, a detailed picture of time distribution and co-dependency of Cr is provided in this research. A highly positive correlation was found between concentrations of Cr and dissolved organic carbon (r = 0.875) in LL, which indicates the co-transport of Cr and dissolved organic carbon through the system. Monitoring results showed that the substrate used in the experiment did not contribute to Cr accumulation in the landfill soil cover, resulting in percolation of a high proportion of Cr back into the waste layers and its circulation in the system. No negative effects on plant growth appeared during the monitoring period. Due to low uptake of Cr by plants (0.10–0.15 mg/kg in leaves and 0.05–0.07 mg/kg in stems of Salix purpurea), the estimated Cr offtake from LL by plants represented only a small proportion of the LL Cr mass load during the observation period, resulting in no dispersion of Cr into the environment through leaf drop.     

Fungal and enzymatic treatment of mature municipal landfill leachate

The aim of our study was to evaluate biotreatability of mature municipal landfill leachate by using white rot fungus and its extracellular enzymes. Leachates were collected in one active and one closed regional municipal landfill. Both chosen landfills were operating for many years and the leachates generated there were polluted by organic and inorganic compounds. The white rot fungus Dichomitus squalens was able to grow in the mature leachate from the closed landfill and as it utilizes present organic matter as a source of carbon, the results were showing 60% of DOC and COD removal and decreased toxicity to the bacterium Aliivibrio fischeri. On the other hand, growth of the fungus was inhibited in the presence of the leachate from the active landfill. However, when the leachate was introduced to a crude enzyme filtrate containing extracellular ligninolytic enzymes, removal levels of COD and DOC reached 61% and 44%, respectively. Furthermore, the treatment led to detoxification of the leachate to the bacterium Aliivibrio fischeri and to reduction of toxicity (42%) to the plant Sinapis alba. Fungal and enzymatic treatment seems to be a promising biological approach for treatment of mature landfill leachates and their application should be further investigated.     

Influence of H2SO4 and ferric iron on Cd bioleaching from spent Ni–Cd batteries

The paper is concerned with biohydrometallurgical methods of cadmium recovery from spent Ni–Cd batteries. Cd leaching efficiency from electrode material in different media (H₂SO₄ and Fe₂(SO₄)₃ solutions), at different Fe(III) concentrations and using the bacteria Acidithiobacillus ferrooxidans were investigated. The main aim of this study was to understand which from the bioleaching products (sulphuric acid or ferric sulphate) play a main role in the bioleaching process of Cd recovery. The influence of Fe ions on Cd leachability was confirmed. The best leaching efficiency of Cd (100%) was reached by bioleaching and also by leaching in Fe₂(SO₄)₃ solution. The results of X-ray diffraction confirmed that no cadmium was present in solid residuum obtained after the Cd bioleaching as well as Cd leaching using solely ferric iron. The use of H₂SO₄ solution resulted in the lowest efficiency of Cd leachability, the presence of hydroxides in electrode materials caused neutralization of the leaching solution and inhibition of Cd leaching.     

Seasonal variations of monosaccharide anhydrides in PM1 and PM2.5 aerosol in urban areas

The concentrations of monosaccharide anhydrides (levoglucosan, mannosan, galactosan) in PM1 and PM2.5 aerosol samples were measured in Brno and ?lapanice in the Czech Republic in winter and summer 2009. 56 aerosol samples were collected together at both sites to investigate the different sources that contribute to aerosol composition in studied localities. Daily PM1 and PM2.5 aerosol samples were collected on pre-fired quartz fibre filters.The sum of average atmospheric concentration of levoglucosan, mannosan and galactosan in PM1 aerosol in ?lapanice and Brno during winter was 513 and 273 ng m^?3, while in summer the sum of average atmospheric concentration of monosaccharide anhydrides (MAs) was 42 and 38 ng m^?3, respectively. The sum of average atmospheric concentration of MAs in PM1 aerosol formed 71 and 63% of the sum of MA concentration in PM2.5 aerosol collected in winter in ?lapanice and Brno, whereas in summer the sum of average atmospheric concentration of MAs in PM1 aerosol formed 45 and 43% of the sum of MA concentration in PM2.5 aerosol in ?lapanice and Brno, respectively.In winter, the sum of MAs contributed significantly to PM1 mass ranging between 1.37% and 2.67% of PM1 mass (Brno – ?lapanice), while in summer the contribution of the sum of MAs was smaller (0.28–0.32%). Contribution of the sum of MAs to PM2.5 mass is similar both in winter (1.37–2.71%) and summer (0.44–0.55%).The higher concentrations of monosaccharide anhydrides in aerosols in ?lapanice indicate higher biomass combustion in this location than in Brno during winter season. The comparison of levoglucosan concentration in PM1 and PM2.5 aerosol shows prevailing presence of levoglucosan in PM1 aerosol both in winter (72% on average) and summer (60% on average).The aerosol samples collected in ?lapanice and Brno in winter and summer show comparable contributions of levoglucosan, mannosan and galactosan to the total amount of monosaccharide anhydrides in both aerosol size fractions. Levoglucosan was the most abundant monosaccharide anhydride with a relative average contribution to the total amount of MAs in the range of 71–82% for PM1 aerosols and 52–79% for PM2.5 aerosols.     

Synthesis of batch water network for a brewery plant

This paper presents an industrial application of mixed-integer nonlinear programming (MINLP) models for the optimisation of a water network, which was initiated by an integral need for cleaner production within a brewery. Several mathematical models were developed in order to reduce the use of freshwater, whilst considering the specific requirements of each particular production section. These models are based on the design method developed by Kim and Smith [1]. The original formulation is modified to enable efficient integration of discontinuous and semi-continuous water-using processes in the packaging area. Semi-continuous processes are treated as water sources of limited capacity. The option of installing storage tanks for semi-continuous water streams is included in the model, in order to re-use these streams during the shutdown periods of semi-continuous operations. The original model is additionally extended with the option of installing local (on-site) wastewater treatment units operating either in batch or semi-continuous modes. This enables the analysing of opportunities for regeneration re-use within the production area, i.e. the brewhouse with a cellar, because of high contaminant concentrations at these sites. The scheduling of batch wastewater treatment units is performed simultaneously in order to adjust the treatment schedule to a fixed schedule of batch processes.     

Eutrophication Phenomenon with Special Reference to the Kasštela Bay

Abstract

The paper discusses the eutrophication phenomenon as a result of pollution from land-based sources with special reference to the experience gained in the Kas?tela Bay Project.

The Bay of Kas?tela is a semi-enclosed bay of a total volume of 1.4 km³. It receives a great amount of untreated waste water, both domestic and industrial.

Results of the analyses of long-term data series of dissolved oxygen, nutrients, transparency and phytoplankton have shown a continuous increase of eutrophication in the Bay. While the concentration of oxygen in the euphotic layer increases due to a higher phytoplankton productivity, in the bottom layer it decreases as a result of the activity of heterotrophic bacteria. the nitrogen/phosphorus ratio in sea water has decreased, and today is much lower than in the open sea. From the Secchi-disc data it is clear that transparency has also decreased for the last three decades. Primary production as well as phytoplankton biomass has also increased. the structure of phytoplankton community has been changed and dinoflagellate species have become dominant rather than diatoms.     

Inactivation of bacteria by sun light in a solar reactor with Immobilised TiO2

The photocatalytical inactivation of bacteria (Escherichia coli, Staphylococcus epidermidis,...) in the flow‐through plate solar reactor by sunlight was investigated. The low stability of bacteria in the reactor was attributed to bacteria sensitivity to mixing and/or gas bubbling. Sunlight inactivation proceeds with sufficient rate even under cloudy conditions.