Nitrogen removal from wastewater and bacterial diversity in activated sludge at different COD/N ratios and dissolved oxygen concentrations

The impact of the organic carbon to nitrogen ratio (chemical oxygen demand (COD)/N) in wastewater and dissolved oxygen (DO) concentration on carbon and nitrogen removal efficiency, and total bacteria and ammonia-oxidizing bacteria (AOB) communities in activated sludge in constantly aerated sequencing batch reactors (SBRs) was determined. At DO of 0.5 and 1.5 mg O₂/L during the aeration phase, the efficiency of ammonia oxidation exceeded 90%, with nitrates as the main product. Nitrification and denitrification achieved under the same operating conditions suggested the simultaneous course of these processes. The most effective nitrogen elimination (above 50%) was obtained at the COD/N ratio of 6.8 and DO of 0.5 mg O₂/L. Total bacterial diversity was similar in all experimental series, however, for both COD/N ratios of 6.8 and 0.7, higher values were observed at DO of 0.5 mg O₂/L. The diversity and abundance of AOB were higher in the reactors with the COD/N ratio of 0.7 in comparison with the reactors with the COD/N of 6.8. For both COD/N ratios applied, the AOB population was not affected by oxygen concentration. Amplicons with sequences indicating membership of the genus Nitrosospira were the determinants of variable technological conditions.     

Road safety performance indicators and their explanatory value: A critical view based on the experience of Central European countries

Counts of road crashes and their victims represent essential information for road safety practitioners allowing them to analyse their spatial and temporal aspects. However, they cannot provide details on the factors causing road crashes. As a result, various road safety performance indicators (RSPIs) were introduced, making it possible to gather information on the effectiveness of interventions on road safety in given areas. However, analysis of the trends in road casualties in several Central European countries based on safety performance (measured by RSPIs) suggest that not even these indicators can provide full understanding of road safety trends, and, if they are applied generally without the required background information, this could even lead to serious misinterpretation of the trends in road casualties. Sudden breaks in long-term trends seem to be linked to the transition process and to certain legislative reforms. The exposure and socio-economic climate appear to have had a major impact on road crash outcomes. Various additional indicators describing organisational and structural aspects may be helpful, therefore, in better understanding and predicting the development in road safety for individual countries.     

An OH&S Management System as a Source of Information

The concept of an occupational health and safety management system (OH&S MS) has become widespread over the past 20 years. However, there are few studies on the subject, they are generally methodologically weak and in many cases cannot be generalized. A formalized OH&S MS is a set of rules and connected elements of the general organization management system which guarantees accomplishment of the organization?s objectives in the area of upgrading safety conditions of both employees and the environment. The need for research on voluntary management systems stems from the necessity to propagate appropriate solutions and their continuous development processes. This paper discusses an OH&S MS as a source of data and essential information on the process of developing a system. It examines the relationship between the degree to which the requirements of Standard No. PN-N-18001:2004 have been adapted and the demand for health and safety data and information.     

Evaluation of zeolite-sand mixtures as reactive materials protecting groundwater at waste disposal sites

To recognize properties of a mixture of Vistula sand (medium sand acc. to USCS) with Slovak zeolite as reactive materials suitable for permeable reactive barriers proposed for protection of groundwater environment in vicinity of old landfills comprehensive laboratory investigations were performed. The present study investigates the removal of contaminants specific for landfill leachates onto zeolite-sand mixtures containing 20%, 50% and 80% of zeolite (ZS20, ZS50 and ZS80). Taking into account the results of batch tests it was concluded that the Langmuir isotherm best fitted the data. It was observed that the presence of ammonium, calcium and magnesium decreases the removal efficiency of copper by 32%. Column tests of contaminant migration through the attenuation zone of the reactive materials were interpreted using the software package CXTFIT, which solves a one-dimensional advection-dispersion equation. Column test results also indicate the strong influence of the presence of interfering substances on copper immobilisation; dynamic sorption capacities decrees twofold. Throughout the landfill leachate flow through ZS80 sample, a constant reduction of NH+4 (at 100%), K+ (at 93%) and Fe total (at an average of 86%) were observed. There was no reduction in chemical oxygen demand and biochemical oxygen demand.     

Effect of weathering product assemblages on Pb bioaccessibility in mine waste: implications for risk management

General assessments of orebody types and associated mine wastes with regard to their environmental signature and human health hazards are needed to help in managing present and historical mine waste facilities. Bioaccessibility tests and mineralogical analysis were carried out on mine waste from a systematic sampling of mine sites from the Central Wales orefield, UK. The bioaccessible Pb widely ranged from 270 to 20,300 mg/kg (mean 7,250 mg/kg, median 4,890 mg/kg), and the bioaccessible fraction from 4.53 to >100 % (mean 33.2 %, median 32.2 %), with significant (p?=?0.001) differences among the mine sites. This implies sensitivity of bioaccessibility to site-specific conditions and suggests caution in the use of models to assess human health impacts generalised on the basis of the mineral deposit type. Mineralogical similarities of the oxidation products of primary galena provided a better control over the observed Pb bioaccessibility range. The higher Pb bioaccessibility (%) was related to samples containing cerussite, irrespective of the presence of other Pb minerals in the mineral assemblage; lower Pb bioaccessibility resulted where anglesite was the main Pb mineral phase and cerussite was absent. A solubility diagram for the various Pb minerals in the waste was derived using PHREEQC model, and the experimental Pb concentrations, measured in the simulated gastric solution, were compared with the equilibrium modelling results. For samples containing cerussite, the model well predicted the soluble Pb concentrations measured in the gastric solution, indicative of the carbonate mineral phase control on the Pb in solution for these samples and little kinetic control on the dissolution of cerussite. On the contrary, most mine waste samples containing dominant anglesite and or plumbojarosite (no cerussite) had lower solution Pb values, falling at or below the anglesite and plumbojarosite solubility equilibrium concentrations, implying kinetic or textural factors hindering the dissolution.     

Trypsin inhibitor,antioxidant and antimicrobial activities as well as chemical composition of potato sprouts originating from yellow- and colored-fleshed varieties

Abstract

Potato sprouts could be a valuable resource of phytochemicals such as secondary plant metabolites, potential antioxidants and nutritive compounds. In this work, potato sprout extracts of five varieties were examined; they differed in major glycoalkaloid content, trypsin inhibitor activity, total polyphenol content and antioxidant activity, as well as in antimicrobial activity against Gram?+?and G???bacteria, and yeast. Sprouts of colored-fleshed tubers were characterized by higher trypsin inhibitor activity than sprouts of yellow potatoes. The strongest microorganism growth inhibition effect was observed for macerate with sprouts from the purple-fleshed Blaue Annelise variety against B. subtilis, whereas C. albicans yeasts were sensitive to macerates with sprouts from purple-fleshed Blue Congo and yellow-fleshed Vineta potato varieties.     

Assessment of organotin pollution along the Polish coast (Baltic Sea) by using mussels and fish as sentinel organisms

Levels of tributyltin (TBT) and its degradation products, mono- (MBT) and dibutyltin (DBT), as well as triphenyltin (TPT), were monitored in 10 stations along the Polish coast (Baltic Sea). Mussel-Mytilus edulis-and fish-Platichthys flesus-were used as sentinel organisms. The bioaccumulation patterns of butyltin and phenyltin compounds varied substantially. Butyltins were detected in mussel tissue from all the sampled stations. Among them, organisms from the Gulf of Gdansk showed the highest residues (68 ng/g w.w. as Sn) in conjunction with elevated TBT/DBT ratios, which suggest recent inputs of TBT in the area. Additionally, flatfish were sampled in the Gulf of Gdansk, and different tissues (liver, digestive tube and gills) were analyzed separately. TPT, although undetected in mussels, was always present in fish. The highest organotin concentration was observed in the liver (369 ng/g w.w. as Sn) of fish caught near Gdansk port. Relatively high concentrations were observed in digestive tube, which points out the ingestion of organotin contaminated food as an important uptake route of those compounds in P. flesus.     

Investigation of PCDD/Fs and dl-PCBs in fish from the southern Baltic Sea during the 2002–2006 period

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs) in the southern Baltic herring (Clupea harengus), sprat (Sprattus sprattus), and salmon (Salmo salar) are reported.The significant interspecies and season-specific differences in PCDD/Fs and dl-PCBs concentrations were observed. The contribution of dl-PCBs to the total toxicity equivalents (TEQs) ranged between 50% and 70%, dependently on fish species. In all samples, concentrations of PCDF were higher in comparison with that of PCDD.The permissible limits of the content of PCDD/Fs and dl-PCBs (8 pg g⁻¹ fresh weight for the sum of PCDD/Fs and dl-PCBs, and 4 pg g⁻¹ fresh weight for the PCDD/Fs) were exceeded mainly in salmon samples (in 80% of salmon samples studied). The elevated levels of PCDD/F and dl-PCB were observed only in two of seventy two herring samples, and in ten of 62 sprat samples.The multiple regression analysis revealed that fish lipid content, and concentration of PCB 153, used simultaneously, might be useful in the prediction of TEQ values of fish samples. These two variables explained more than 80% of total variance. For all fish species studied, the correlation coefficients obtained with the multiple regression analysis were higher than that obtained with the regression analysis involving total TEQ values, and only one independent variable: fish lipid content.     

Health hazards related to conidia of Cladosporium—biological air pollutants in Poland, central Europe

The spores of Cladosporium Link. are often present in the air in high quantities and produce many allergenic proteins, which may lead to asthma. An aerobiological spore monitoring program can inform patients about the current spore concentration in air and help their physicians determine the spore dose that is harmful for a given individual. This makes it possible to develop optimized responses and propose personalized therapy for a particular sensitive patient. The aim of this study was to assess the extent of the human health hazard posed by the fungal genus Cladosporium. For the first time, we have determined the number of days on which air samples in Poland exceeded the concentrations linked to allergic responses of sensitive patients, according to thresholds established by three different groups(2800/3000/4000 spores per 1 m~3 of the air). The survey was conducted over three consecutive growing seasons(April–September, 2010–2012) in three cities located in different climate zones of Poland(Poznan, Lublin and Rzeszow). The average number of days exceeding 2800 spores per cubic meter(the lowest threshold) ranged from 61(2010) through 76(2011) to 93(2012), though there was significant variation between cities. In each year the highest concentration of spores in the air was detected in either Poznan or Lublin, both located on large plains with intensive agriculture. We have proposed that an effective, science-based software platform to support policy-making on air quality should incorporate biological air pollutant data,such as allergenic fungal spores and pollen grains.