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Open access

Sayiter Yildiz

Abstract

In this study, ANN (artificial neural network) model was applied to estimate the Ni(II) removal efficiency of peanut shell based on batch adsorption tests. The effects of initial pH, metal concentrations, temperature, contact time and sorbent dosage were determined. Also, COD (chemical oxygen demand) was measured to evaluate the possible adverse effects of the sorbent during the tests performed with varying temperature, pH and sorbent dosage. COD was found as 96.21 mg/dm3 at pH 2 and 54.72 mg/dm3 at pH 7. Also, a significant increase in COD value was observed with increasing dosage of the used sorbent. COD was found as 12.48 mg/dm3 after use of 0.05 g sorbent and as 282.78 mg/dm3 after use of 1 g sorbent. During isotherm studies, the highest regression coefficient (R 2) value was obtained with Freundlich isotherm (R 2 = 0.97) for initial concentration and with Temkin isotherm for sorbent dosage. High pseudo-second order kinetic model regression constants were observed (R 2 = 0.95-0.99) during kinetic studies with varying pH values. In addition, Ni(II) ion adsorption on peanut shell was further defined with pseudo-second order kinetic model, since qe values in the second order kinetic equation were very close to the experimental values. The relation between the estimated results of the built ANN model and the experimental results were used to evaluate the success of ANN modeling. Consequently, experimental results of the study were found to be in good agreement with the estimated results of the model.

Open access

Kamil Błażej Pochwat and Daniel Słyś

Abstract

One of the essential needs for retention reservoirs is to reduce the volume of wastewater flows in sewer systems. Their main advantage is the potential to increase retention in the system, which in turn improves hydraulic safety by reducing the risk of node flooding and the emergence of the phenomenon of “urban flooding”. The increasingly common use of retention reservoirs, the observed changes in the climate and the development of dedicated software tools necessitate the updating of the methods used to dimension retention reservoirs. So far, the best known procedures in this regard involve the application of analytical formulas and tools in the hydrodynamic modelling of current sewage systems. In each case the basis for the retention facility design is the evaluation of rainfall in terms of the probability of occurrence and duration that would result in a critical rainwater flow condition in the sewer system in order to define the required reservoir retention capacity. The purpose of this paper is to analyse of the feasibility of applying artificial neural networks in the preliminary estimation of the duration of critical rainfalls. Such an application of these networks is essential to the process of hydrodynamic modelling of the system and to determining the required retention capacity of the reservoir. The study used an artificial neural network model typically used as part of planning processes, as well as the Statistica software suite.

Open access

Grażyna Sakson, Marek Zawilski and Agnieszka Brzezińska

Abstract

Combined sewer systems in cities are increasingly equipped with additional storage facilities or other installations necessary for keeping the wastewater treatment plants from overloading during wet weather and reducing combined sewer overflows into receiving waters. Effective methods for reducing such negative phenomena include the temporary storage of wet weather flow in an end-of-pipe separate tank or in a sewer system. In this paper, four scenarios of wastewater storage for the Group Wastewater Treatment Plant (GWWTP) in Lodz (Poland) have been analysed: a storage in a separate single tank located in GWWTP, a storage in the bypass channel in GWWTP, in-sewer storage, and a combination of the aforementioned variants, also with real time control (RTC) system introduced. The basic calculations were performed using the EPA’s SWMM software for the period of 5 years (2004-2008). The chosen solution - storage in a separate storage tank - has been verified based on the inflow dataset from the years 2009-2013. The specific volume of the separate storage tank should be at least 22 m3 per hectare of impervious catchment area, but it could be reduced if additional in-sewer storage with RTC were introduced. Both options allow the effective protection of receiving waters against discharge of untreated sewage during wet weather.

Open access

Joan S. Adriano, Glenn G. Oyong, Esperanza C. Cabrera and Jose Isagani B. Janairo

Abstract

The field of microbial biotechnology has revolutionized the utilization of microorganisms to overcome the problems of environmental pollutions. The present study aimed to identify silver-tolerant isolates and screen their ability to synthesize silver nanoparticles for possible use as bioremediation agents. Seventeen bacterial isolates from soil collected from the Smokey Mountain landfill in Manila, Philippines, were found to tolerate 0.01 M AgNO3 in the culture medium. Molecular and phylogenetic analyses using the 16S rRNA gene sequence identified the isolates as Bacillus cereus, Bacillus subtilis, Bacillus flexus, Bacillus thuringiensis, Alcaligenes faecalis, Achromobacter sp. and Ochrobactrum sp. The formation of silver nanoparticles was evident in the change in color of the reaction mixtures, and was detected through UV-VIS spectroscopy with absorbance peaks at 250-300 nm and 400-450 nm. Scanning electron microscopy revealed the aggregation of diverse shapes of silver nanoparticles with sizes ranging from 70 to 200 nm. The best silver nanoparticle-synthesizing isolates were Alcaligenes faecalis and Bacillus cereus. The results denote the promising microbial technology application of the 17 silver-tolerant isolates in combating the adverse effects of metals and other pollutants in the environment.

Open access

Ilona Wrońska and Krystyna Cybulska

Abstract

One of the methods for recovery and utilization of waste products from the poultry industry is to subject them to the methane fermentation process in the biogas plant. These are waste with a high content of fatty compounds and proteins, including keratin. Their specificity is characterized by rapid possibility of spoilage, rancidity and problems of further management. These wastes are characterized by varying degrees of complexity, thus their use as a raw material for the biogas fermenter should be preceded by a pre-treatment. An example of waste generated in poultry processing is biological sludge. Optimizing this material with highly enzymatic fungi could accelerate the degradation of the organic matter contained and, as a result, increase the energy efficiency of this type of waste. Quantitative and qualitative parameters of biogas produced from biological sludge processed by isolated filamentous fungi with high metabolic potential were determined. Laboratory tests were based on the modified methodology included in the standards DIN 38414-S8 and VDI 4630. Based on the results obtained, it was found that the pre-optimization of biological sludge by fungal strains with different metabolic potential, influences on the yield of biogas production, including methane. There was an increase in the biogas yield from the biological sludge processed by the mixed fungal consortium (by 20 %) and the strain marked as F1 (by 14 %) as compared to the non-inoculated material, which was also reflected in the amount of methane produced in the case of the mixed fungal consortium (by 28 %) and the strain marked as F1 (by 12 %).

Open access

Agnieszka Gąszczak, Grażyna Bartelmus, Izabela Greń and Daniel Janecki

Abstract

The microbial degradation of vinyl acetate (VA) by Pseudomonas fluorescens PCM 2123 strain was studied in both batch and continuous modes. The purpose of the experiments was to determine the kinetic model of the cell growth and biodegradation rate of vinyl acetate (VA), which was the sole carbon and energy source for tested microorganisms. The experiments, carried out in a batch reactor for several initial concentrations of growth substrate in the liquid phase ranging from 18.6 to 373 gsubstrate·m−3 (gs·m−3) made it possible to choose the kinetic model and to estimate its constants. The Haldane inhibitory model with the values of constants: μm = 0.1202 h−1, KS = 17.195 gs·m−3, Ki = 166.88 gs·m−3 predicted the experimental data with the best accuracy. To set the parameters of maintenance metabolism it was necessary to carry out a series of continuous cultures at different dilution rates (0.05 to 0.072 h−1) and concentrations of VA in the liquid supplied to the chemostat ranging from 30.9 to 123.6 gs·m−3. The obtained data-base enabled to determine the coefficient for maintenance metabolism (me = 0.0251 gsubstrate gcell dry weight −1·h−1 (gs·gcdw −1·h−1)) as well as the maximal and observed values of yield coefficients, Yxs M = 0.463 gcdw·gs −1 and (Yxs)obs = 0.411 gcdw·gs −1, respectively. The developed kinetics was verified by comparison of the computed and obtained in batch experiments profiles of changes in biomass and growth substrate concentrations.

Open access

Iwona Deska, Maciej Mrowiec, Ewa Ociepa and Katarzyna Łacisz

Abstract

Progressive economic development as well as urbanisation influence the characteristics of the stormwater runoff. Progressive sealing of drainage basin surface prompts the decrease of rainwater infiltration, thus increasing the runoff intensity. This results in an increase of flood risk. Thus, in urban areas the sustainable urban drainage systems (SUDS) are used in addition to the traditional sewer systems. The examples of SUDS strategy are, inter alia, the roofs covered with vegetation (the green roofs). The paper presents the results of research of retention capacities of 4 diverse green roof models with following growing media: (1) the typical green roof substrate without any additions, (2) the substrate with addition of about 1 % by weight of hydrogel (the cross-linked potassium polyacrylate), (3) the substrate with addition of about 0.25 % by weight of hydrogel, (4) the substrate with addition of expanded clay and perlite. The models did not have the vegetation layers in order to explore only the retention capacities of drainage layers and substrates. The aim of the first part of research was to investigate the retention capacities of green roof models after 1, 2, 6, 8 and 10 antecedent dry days. In the case of 1 and 2 antecedent dry days the best medium retention capacity had green roof model 2 (with substrate with addition of 1 % by weight of hydrogel), and the weakest medium retention capacity had green roof model 1 (without any additions). In the cases of precipitations which occurred after 6 as well as 8 and 10 antecedent dry days the best retention capacity had green roof model 3 (with addition of about 0.25 % by weight of hydrogel). The weakest retention capacity had in these cases green roof model 4 (with addition of expanded clay and perlite). The aim of the second part of research described in the paper was to investigate the retention capacities of green roof models during precipitations that occurred after long antecedent dry periods of time (34, 59 and 106 antecedent dry days). The substrates and drainage layers were air-dry directly before precipitations. The best retention capacity had in this case green roof model 3 (with the substrate with addition of about 0.25 % by weight of hydrogel). The second largest retention capacity had model 2 (with the substrate with addition of about 1 % by weight of hydrogel). The definitely weakest retention capacity had model 4 containing the substrate with addition of expanded clay and perlite. The results may indicate that the efficacy of hydrogel decreased over time probably due to its decay under the influence of solar radiation.

Open access

Sayiter Yildiz and Selahattin Sevinç

Abstract

Drinking water treatment plants produce significant amounts of waste sludge. In this study, removal of Nickel ion by use of wastewater sludge was aimed. The adsorption capability of waste sludge was optimized with varying physical parameters such as pH, adsorbent dosage, adsorbate concentration, contact time, shaking speed and temperature. Initial concentration was set as 25 mg/dm3, absorbent dose was set as 0.3 g/cm3, and temperature was set as 25 °C. Compliance of balance data with Langmuir, Freundlich, Temkin and D-R isotherm models was investigated. The highest R 2 values were obtained with Freundlich isotherm (R 2 = 0.92-0.95). Adsorption kinetics was analysed using pseudo-first order, pseudo-second order, Weber and Morris intraparticle diffusion and Elovich kinetic models, and the system was found to be in a better compliance with pseudo-second order kinetic model. Iron sludge was used as sorbent, and accordingly total iron ion measurements were carried out to determine its possible effects on water. Additionally, SEM, EDX, FTIR spectroscopy, XRD spectrum and atomic force microscope (AFM) measurements were conducted to determine the interaction between the sorbent and metal ions, in addition to characterization of the sorbent. As indicated by research results, drinking water treatment sludge proved to be a potential adsorbent for removal of nickel(II) ions from the solution.

Open access

Marta Marszałek, Zygmunt Kowalski and Agnieszka Makara

Abstract

Pig slurry is classified as a natural liquid fertilizer, which is a heterogeneous mixture of urine, faeces, remnants of feed and technological water, used to remove excrement and maintain the hygiene of livestock housing. The storage and distribution of pig slurry on farmland affect the environment as they are associated with, among others, the emission of various types of gaseous pollutants, mainly CH4, CO2, N2O, NH3, H2S, and other odorants. Methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) are greenhouse gases (GHGs) which contribute to climate change by increasing the greenhouse effect. Ammonia (NH3) and hydrogen sulfide (H2S) are malodorous gases responsible for the occurrence of odour nuisance which, due to their toxicity, may endanger the health and lives of humans and animals. NH3 also influences the increase of atmosphere and soil acidification. The article presents the environmental impact of greenhouse gases and odorous compounds emitted from pig slurry. Key gaseous atmospheric pollutants such as NH3, H2S, CH4, CO2 and N2O have been characterized. Furthermore, methods to reduce the emission of odours and GHGs from pig slurry during its storage and agricultural usage have been discussed.

Open access

Agnieszka Rombel-Bryzek, Małgorzata Rajfur, Olga Żuk and Patryk Zając

Abstract

As a heavy metal, cadmium has strongly toxic effects on plants and can induce oxidative stress. It is absorbed by the roots and transported to the stems and leaves. The aim of the study was to evaluate the effect of various concentrations of cadmium on the metabolic activity of Beta vulgaris and assess the dependence of these processes on the content of metal in the plants. To demonstrate the effect of cadmium on metabolism, protein and photosynthetic pigment content, lipid peroxidation, and the activity of enzymes specific for oxidative stress in roots and shoots were measured. Seeds of B. vulgaris were treated with different concentrations of Cd supplied via a CdCl2 solution: 0 (control), 200, 300 and 400 mg/dm3. Results of the present study revealed increased GPOX activity as cadmium concentration rose, while SOD activity was stimulated by a low Cd concentration (200 mg/dm3) and reduced by high levels of Cd. Based on the present findings, it can be concluded that GPOX in B. vulgaris played a more important role in ROS scavenging than SOD did and was able to reduce the level of lipid peroxidation in plants. Cadmium, in the concentration range used, did not show any significant effect on protein or photosynthetic pigment content.