The effects of activated sludge sonication on floes surface properties and heavy metal uptake was investigated. Negative surface charge and specific surface area were estimated by correlation with dye adsorption whereas relative hydrophobicity was measured by adhesion to hexadecane. Experimental results show that ultrasound treatment leads to a simultaneous increase of specific surface area and availability of negatives and/or hydrophilic sites. Thus, fixation sites for heavy metal uptake are made free by sonication. Both increase of specific surface area and fixation sites availability leads to an increase of uptake of Cd(II). For Cu(II), organ.ie matter released in soluble phase during the treatment acts as a ligand and limits adsorption on floes surface.

Spent-filter backwash water is usually discharged into sewers or returned to the head of a water treatment plant (WTP) to be re-processed. The purpose of this study was to characterize and compare two different WTP filter backwash water contents that were obtained by using conventional and air scour backwash methods, and influence the recycling of spent-filter backwash water. For this purpose, the spent-filter backwash water was analyzed at two different Lithuanian WTPs i.e. one using a conventional backwash method and another using an air scour backwash method (Eades, 2001). The impact of recycling spent-filter backwash on the treated water's quality was evaluated by comparing the concentration of the total iron content with suspended solids in the filtered water by following legislation rules. Backwash water in this research contained a significant concentration of total iron and a large amount of suspended solids. In this study it was found that, conventional sedimentation by gravity was sufficient for the removal of suspended solids and iron from the backwash water. Further, the presence of analyzed chemical compounds accumulating into the backwash water after sedimentation had no significant impact on the filtration's effectiveness. Therefore, this research shows that air-scour backwash water can be recycled in the same way as conventional backwash water, but a different sedimentation rate needs to be evaluated.

Levels and distribution of selected polybrorninated diphenyl ether congeners in dust samples taken from different indoor environments in Lublin, South-Eastern Poland, are reported. The most abundant congeners, found in the majority of sampling sites, were BOE 47, 100 and 28, respectively. The highest levels of examined congeners were observed in dust samples taken from a computer repair facility and labs. BOE 47, 99 and 100, occurring at highest levels and having the greatest contribution confirm that in Polish indoor environments polymer products contain Penta - BOE technical mixture.

In the study we have focused on the distribution of several metals (Cr, As, Pb) and anions (Cr, NO3-) and their partition between pore (interstitial) waters and sediments sampled at three stations at the Dobczyce Reservoir which supplies the drinking water to inhabitants from the city of Kraków and its agglomeration. The results show considerable increase in concentrations of Pb and As in pore water samples, when compared to the bottom waters. Meaningful alternations in concentration were observed in case of pore water samples (Pb, As) and sediments (Cr, Pb, As), coming from three stations and their lateral sections. The possible relations between this phenomenon and the sediment characteristic as well as the Fe and Ca content, has been studied. Some comments on the seasonal variations of anion contents in water and pore water samples, are also provided. It was found that nitrates and sulphates show considerable variations.

The present studies aimed at comparing the effect of the potassium monoionic form (prepared from a model spent ion exchanger) and a conventional potassium fertilizer (KCI) on plant vegetation after addition to depleted soil. To achieve the study aim a pot experiment using orchard grass (Dacrylis glomerata L.) as the test plant was carried out. The vegetation cycle lasted seven weeks. The plants were grown on four series of media: on untreated soil, on soil with added monoionic K form, on soil with added KCI and on soil with Biona-312 substrate added (2% v/v). Biona-312 served as the control fertilizer containing all macro- and microelements. The application of monoionic potassium form positively influenced orchard grass vegetation. The addition of K form into soil increased stem wet and dry biomass, root dry biomass and total dry yield by 15, 10, 13 and 12%, respectively. Bearing in mind that the amount of dry plant matter as source material for humus formation is crucial in soil reclamation, the effectiveness of potassium monoionic form was found to be similar to that of the mineral fertilizer - KCI. Biona-312 was the most efficient fertilizer used in the study, resulting in the greatest yield of Dactylis glomerata L.

Biomethanization of mixed organic substances is the effect of coexistence of numerous groups of microorganisms. Methanogenic degradation of such substances involves at least three different trophic groups of anaerobes, namely fermentative heterotrophs, proton-reducing syntrophs and methanogenic archaea. The development of molecular techniques allowed to detect some new groups of bacteria and archea, which often stay unculturable. The cultivation of uncultured organisms is of great significance in recognizing the function of these organisms. In the past few years, newly discovered microorganisms have been successfully isolated from anaerobic sludges, and the information regarding their physiology in connection with phylogeny is updated regularly.

The paper describes the most important factors controlling the process of methanogenesis in the biomethanization technology. It discusses the operational regimes of temperature as well as pH, C/N ratio, the necessity for micronutrients and sensitivity to a number of toxic compounds. Components with an inhibitory effect are characterized as biostatic compounds (ammonia, VFAs, hydrogen sulfide and salinity-inducing substances) and biocidal substances (such as surfactants and pharmaceuticals). The threshold limits of the compounds in question securing the system against disturbances are introduced, as well as the measures counteracting inhibition. Some ways of overcoming the negative impact of environmental factors on the system are presented, including co-fermentation, supplementation of nutrients, removal of ammonia and hydrogen sulfide by different methods and acclimatization of methanogens to inhibitory substances.

The landfill gas (LFG), produced during decomposition of the organic fraction of waste is a major source of air pollutants. It consists mainly of methane and carbon dioxide, but also contains additional gases, such as nitrogen, oxygen, hydrogen, carbon monoxide, hydrogen sulphide, and a large number of trace components. Aliphatic and aromatic hydrocarbons, halogenated hydrocarbons, heterocyclic compounds, alcohols, aldehydes, ketones, terpenes and siloxanes belong to this group. This work presents the results of field studies concerning the concentration of over fifty non-methane organic compounds in municipal solid waste landfill gas. The sites examined were located in the Middle East macroregion of Poland. The landfills were different in the respect to size, morphology, and age of stored waste. The results reveal that the highest concentrations of the majority of the examined compounds were observed in gas released from the largest landfill at which the waste was not pre-treated prior to deposition. Concentrations often exceeded those found in the literature data. Deposition of waste after separation of biofraction and recyclable materials significantly decreased concentrations of the majority of NMOCs in the LFG.

The present work focuses on problems connected with the location and sampling method for pecton (biofilm) in sewage treatment plants. We also discuss the amount and quantity of pecton necessary to compose a representative sample. Comparisons of other selected contamination indicators in place of pecton sampling, are also presented. Research carried out at the WWTP "Hajdow" demonstrated that everything (starting from grid chambers), coming into contact with sewage surfaces is covered with biofilm This biological formation does not cause any significant changes in sewage quality due to its relatively small surface compared to the sewage flux. As presented in the following analysis, pecton can be used for bioindication of sewage quality. This is possible because the organisms forming these communities use substances contained in flowing sewage as nutritional substrates. In such cases the wastewater purification level in biological sewage treatment plants can, in a way similar to rivers, be determined based on bioindication methods using existing similarities between the prevailing processes and organisms.

Maintenance of assets and equipment in power plants is essential for their safety and is required to help the plant stay active. In this paper, the specimens manufactured from a pipe of X10CrMoVNb9-1 (P91) power engineering steel in the as-received state and after operating for 80000 h at internal pressure of 8.4 MPa and temperature of 540ºC were subjected to tests using electronic speckle pattern interferometry (ESPI) under static loading of up to 2.5 kN. Such a procedure enables assessment of strain and stress distribution maps to compare material integrity in the as-received state and after exploitation in its elastic range. The measurements conducted showed no effect of long time operation on the mechanical response of P91 steel under the power installations conditions since the field strain distributions for each type of specimen were found to be similar.

In this work, two robust zeroing neural network (RZNN) models are presented for online fast solving of the dynamic Sylvester equation (DSE), by introducing two novel power-versatile activation functions (PVAF), respectively. Differing from most of the zeroing neural network (ZNN) models activated by recently reported activation functions (AF), both of the presented PVAF-based RZNN models can achieve predefined time convergence in noise and disturbance polluted environment. Compared with the exponential and finite-time convergent ZNN models, the most important improvement of the proposed RZNN models is their fixed-time convergence. Their effectiveness and stability are analyzed in theory and demonstrated through numerical and experimental examples.

The inventory systems are highly variable and uncertain due to market demand instability, increased environmental impact, and perishability processes. The reduction of waste and minimization of holding and shortage costs are the main topics studied within the inventory management area. The main difficulty is the variability of perishability and other processes that occurred in inventory systems and the solution for a trade-off between sufficient inventory level and waste of products. In this paper, the approach for resolving this trade-off is proposed. The presented approach assumes the application of a state-feedback neural network controller to generate the optimal quantity of orders considering an uncertain deterioration process and the FIFO issuing policy. The development of the control system is based on state-space close loop control along with neural networks. For modelling the perishability process Weibull distribution and FIFO policy are applied. For the optimization of the designed control system, the evolutionary NSGA-II algorithm is used. The robustness of the proposed approach is provided using the minimax decision rule. The worst-case scenario of an uncertain perishability process is considered. For assessing the proposed approach, simulation research is conducted for different variants of controller structure and model parameters. We perform extensive numerical simulations in which the assessment process of obtained solutions is conducted using hypervolume indicator and average absolute deviation between results obtained for the learning and testing set. The results indicate that the proposed approach can significantly improve the performance of the perishable inventory system and provides robustness for the uncertain changes in the perishability process.