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The Use of Two-Diode Substitute Model in Predicting the Efficiency of PV Conversion in Low Solar Conditions

Abstract

The article presents theoretical foundations of a two-diode equivalent model of a photovoltaic cell/module (PV), together with calculation procedures. A physical interpretation of individual components of an equivalent model was presented. Its practical application in predicting efficiency of operation of various PV cells and modules in low insulation conditions was demonstrated. The obtained predictions were verified with the actual results of their operation in open space (outdoor). The practical suitability of the “model” in early detection of ageing phenomena, such as, for example, absorber degradation taking place in PV modules, was demonstrated. The article was prepared on the basis of the results of testing five different PV modules with various constructions, made of different materials and absorbers, such as: c-Si, mc-Si, CIS, a-Si_SJ, a-Si_TJ. The used measurement data were collected during the 16-year period of the experimental PV modules testing system operation in University of Opole, equipped with a data acquisition system.

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Voltammetric Determination of Aclonifen at a Silver Amalgam Electrode in Drinking and River Water

Abstract

A method for the determination of pesticide Aclonifen (AC) in drinking and river water by differential pulse voltammetry (DPV) on a meniscus modified silver solid amalgam electrode (m-AgSAE) using solid phase extraction (SPE) as a cleanup and preconcentration procedure is described. The limit of detection (LOD) for direct DPV determination of AC in deionized water is 2.7·10-8 mol·dm-3. LOD for DPV determination of AC in tap water after SPE is 1.6·10-10 mol·dm-3, the recovery being 55%. LOD for the determination of AC in Vltava river water is 1.9·10-9 mol·dm-3, the recovery being 65%. Humic acids interfere with the determination in river water; this problem can be resolved by adjusting the pH of the extracted sample to 6. The advantages of this approach are high sensitivity, low LOD, quick and easy sample preparation and fast determination.

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Application of Artificial Neural Networks to the Technical Condition Assessment of Water Supply Systems

Abstract

The paper explains a method for discerning the parts of a water supply system in need of renovation. The results are based on technical data collected over the last twenty one years, concerning more than two hundred sections of both renovated and nonrenovated pipelines. In the study, an appropriately prepared data set was used for training an artificial neural network (ANN) in the form of a multilayer perceptron (MLP). Further comparison between the responses of the trained MLP and the decisions made by human experts showed satisfactory consistency, although 15% of the database records produced certain discrepancies. The presented method can help create an expert system capable of supporting failure-free operation of a water distribution system.

Open access
Application of Neural Networks in Diagnostics of Chemical Compounds Based on their Infrared Spectra

Abstract

The paper presents possibilities of using the so-called „finger-print“ identification method and artificial neural network (ANN) for diagnosis of chemical compounds. The construction of a tool specifically developed for this purpose and the ANN, as well as the required conditions for its proper functioning were described. The identification of chemical compounds was tested in two different ways for proving correctness of the assumptions. First of all, initial studies were carried out with the objective to verify the proper functioning of the developed procedure for IR spectrum interpretation. The second research stage was to find out how the properties of artificial neural networks will satisfy identification or differentiation in case of spectra with very similar structures or for mixtures consisting of several chemical compounds. Interpretation of infrared spectra of mono-constituent substances was successfully performed for both - the training and test data. Interpretation process of infrared spectra of bi-component substances, based on the example of structurally related compounds obstructing identification process, should also be described as positive. The model was able to interpret spectra of mixtures, which were previously registered into the database. Unfortunately, the program is not always able to determine which chemical substances reflect their presence in the infrared spectrum of ternary mixtures. During the research tests, it was also noted that the more complex the structure of a substance being present in the mixture was, the more difficult the interpretation of the spectra to be carry out properly by the program was. On the other hand, positive results were obtained for mixtures of compounds with not so complex structure. It must be emphasized that the results so far are promising and more attention should be paid to them in further studies.

Open access
Application of Selected Methods of Black Box for Modelling the Settleability Process in Wastewater Treatment Plant

Abstract

The paper described how the results of measurements of inflow wastewater temperature in the chamber, a degree of external and internal recirculation in the biological-mechanical wastewater treatment plant (WWTP) in Cedzyna near Kielce, Poland, were used to make predictions of settleability of activated sludge. Three methods, namely: multivariate adaptive regression splines (MARS), random forests (RF) and modified random forests (RF + SOM) were employed to compute activated sludge settleability. The results of analysis indicate that modified random forests demonstrate the best predictive abilities.

Open access
Enzymatic Activity of Some Industrially-Applied Cellulolytic Enzyme Preparations

Abstract

Enzymatic hydrolysis is the essential step in the production of 2nd generation biofuels made from lignocellulosic biomass, i.e. agricultural or forestry solid wastes. The enzyme-catalysed robust degradation of cellulose and hemicellulose to monosaccharides requires the synergistic action of the independent types of highly-specific enzymes, usually offered as ready-to-use preparations. The basic aim of the study was to experimentally determine the enzymatic activity of two widely industrially-applied, commercially available cellulolytic enzyme preparations: (i) Cellic® CTec2 and (ii) the mixture of Celluclast® 1.5L and Novozyme 188, in the hydrolysis of pre-treated lignocellulosic biomass, i.e. (a) energetic willow and (b) rye straw, or untreated (c) cellulose paper as well, used as feedstocks. Before the hydrolysis, every kind of utilized lignocellulosic biomass was subjected to alkaline-based (10% NaOH) pre-treatment at high-temperature (121°C) and overpressure (0.1 MPa) conditions. The influence of the type of applied enzymes, as well as their concentration, on the effectiveness of hydrolysis was quantitatively evaluated, and finally the enzyme activities were determined for each of tested cellulolytic enzyme preparations.

Open access
Fate and Removal of Pharmaceuticals and Illegal Drugs Present in Drinking Water and Wastewater

Abstract

Rapid development of pharmaceutical industry, and thus widespread availability of different types of therapeutical and increased intake of pharmaceuticals, results in elevated concentrations of pharmaceuticals in municipal wastewater subjected to treatment in wastewater treatment plants. Pharmaceuticals present in raw wastewater discharged from hospitals, households, veterinary and health care clinics eventually end up in wastewater treatment plants. Commonly applied methods for treating wastewater do not allow complete removal of these contaminants. As a consequence, pharmaceuticals still present in treated wastewater are introduced to water environment. The most frequently identified pharmaceuticals in surface water belong to the following groups: non steroidal anti inflammatory drugs, beta-blockers, estrogens and lipid regulators. The most difficult is removal of diclofenac, clofibric acid and carbamazepine as these substances show low biodegradability. Diclofenac can be removed in the process of wastewater treatment by 40%, carbamazepine by 10%, and clofibric acid from 26 to 50%. The presence of diclofenac sodium in the rivers in Poland was confirmed and the concentrations were following: 380 ng/dm3 (the Warta river), 470 ng/dm3 (the Odra river), 140 ng/dm3 (the Vistula river). Naproxene was found in the Warta river at the concentration of 100 ng/dm3. The presence of pharmaceuticals in surface water can be toxic to aqueous microorganisms and fish. Recent studies confirmed also the presence of pharmaceuticals in drinking water. This is considered as a problem especially in urban agglomerations such as Berlin or large cities in Spain and China. The studies showed that pharmaceuticals were also identified in the samples taken from the Polish rivers and drinking water. The presence of naproxene and diclofenac at the concentrations of 13 and 4 ng/dm3 was identified in drinking water sampled from water intakes in Poznan. Surface water and drinking water showed also the presence of illegal drugs.

Open access
Influence of Selected Coagulants of Indicator and Dioxin-Like PCB Removal from Drinking Water

Abstract

The aim of the research was to compare selected coagulants efficiency in indicator and chosen dioxin-like PCB removal from surface water. As coagulants, there were used aluminium sulfate and 5 hydrolyzed polyaluminium chlorides, with trade names: PAX-XL1, PAX-XL10, PAX-XL19, PAX-XL60, PAX-XL69. For the research, surface water was used, collected from dam reservoir. The water composition was modified with standard mixtures PCB MIX24 and MIX13, in order to obtain concentration of each congener equal to 300 ng/dm3. The PCB MIX24 mixture was composed of indicator congeners solution: 28, 52, 101, 118, 138, 153, and 180, whereas the MIX13 mixture - solution of three dioxin-like PCB 77, PCB 126, and PCB 169. It was demonstrated that the application of aluminium sulfate allowed for reaching better effects for purifying water of PCB, than with the usage of pre-hydrolyzed salts, polyaluminium chlorides. Out of the studied coagulants, the best effects for indicator PCB removal were obtained with the application of aluminium sulfate, total PCB concentration was decreased by 65%. The highest efficiency for indicator congeners removal (90%) was obtained for PCB 138 and 153. After the application of hydrolyzed polyaluminium chlorides PAX-XL1, PAX-XL10 decrease in higher chlorinated PCB concentration was obtained, in the range of 23 to 74%. Selectivity of chosen PCB congener removal, depending on applied coagulant, was demonstrated; with the usage of aluminium sulfate, removal of heptachlorobiphenyl PCB 180 at the level of 34% was obtained, whereas with the application of PAX-XL1 and PAX-XL10 higher reduction efficiency for this congener was obtained, i.e. 83 and 74% respectively. For dioxin-like PCB, after application of aluminium sulfate, total concentration reduction by 74% was obtained, efficiency of this congeners removal amounted to from 54 (PCB 77) up to 72% (PCB 126), similar results were obtained after the usage of PAX-XL1. The lowest PCB removal from water rate was stated for coagulants PAX-XL60 and PAX-XL69.

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Kinetic and Isotherm Analysis of Cu(II) Adsorption onto Almond Shell (Prunus Dulcis)

Abstract

In the work, adsorption of Cu2+ ions onto almond shell were investigated under different operational conditions. Almond shell was used without any pretreatment prior to the tests. The optimum conditions for adsorption of Cu2+ ions through almond shell were determined to be; pH 5.0, temperature 20°C, shaking rate 125 rpm, sorbent dose 0.3 g and initial Cu2+ ion concentration 50 mg/dm3. The equilibrium duration of the system was 60 minutes. The sorption capacities of the sorbents were predicted with the aid of equilibrium and kinetic models. The interactions of peanut shell with metal ions were constituted by SEM, EDX, FT-IR, XRD and AFM. The pseudo-first-order, pseudo-second-order, Weber-Morris, Elovich model and Bangham kinetic models were applied to test the experimental data. The Cu+2 ions adsorption onto almond shell was better defined by the pseudo-second-order kinetic model, for initial pH. The equilibrium data were evaluated using Langmuir, Freundlich, Temkin, D-R and Harkins Jura isotherms. The highest R2 value in isotherm studies was obtained from Langmiur isotherm (R2 = 0.98) for the inlet concentration.

Open access
Potential Use of Alluvial Groundwater for Irrigation in Arid Zones - Mhamid Oasis (S Morocco)

Abstract

In arid zones, the availability of fresh water is usually very limited because of high salinity, which greatly limits their use for irrigation purposes. High mineralization of water used for irrigation leads to increased soil salinity. The aim of the study was to examine the potential use of alluvial groundwater for irrigation in arid zones. The works were conducted in the Middle Draa Valley in southern Morocco (the Mhamid Oasis) in October 2015. Water samples of alluvial groundwater were collected for laboratory analysis from 42 wells located in the oasis. In order to determine the possibility to use the water for irrigation purposes, the Sodium Adsorption Ratio (SAR), sodium percentage (%Na), permeability index (PI), Kelly’s ratio (KR), magnesium hazards (MH) and electrical conductivity (EC) were assessed. EC values, exceeding 3000 μS·cm-1 in all the samples, classify the water as unsuitable for irrigation. MH and the KR indexes show that 30% of water samples represent levels making them unsuitable for irrigation. SAR confirms the very high degree of susceptibility of the analyzed waters to salinity hazard. The PI index of these waters is moderate, however in terms of sodium content they can be deemed suitable for irrigation purposes. It has been found that even within a small area of the oasis, a very large differentiation in the alluvial groundwater suitability for irrigation purposes occurs.

Open access