Abstract:The paper presents a study on the possibility of using the laser diffraction method for measuring the size of the activated sludge particles. Susceptibility of the particles to mechanical disintegration, dependent on the programmed value of stirring intensity, was observed (stirring was caused by required dynamic flow of analysed suspension through the measurement unit). According to the conclusions presented in this paper, it may be assumed that the laser diffraction method can be applied for measurement of activated sludge particle diameters under the following conditions: 1) the size of activated sludge particles measured by the laser diffraction method is not a real value, but after standardisation of measurement conditions can be treated as a parameter describing the sludge; 2) the particle diameters of activated sludge should be stabilised before the measurement, eg by mixing in the measurement unit or by ultrasound waves application.Keywords: laser diffraction method, activated sludge particles diameter An activated sludge process efficiency is dependent on the properties of saprophytes and saprobes conglomerated in flocks [1][2][3][4][5][6][7][8]. Among the important properties of activated sludge you can enumerate eg metabolic activity [9,10], ease of separation from treated sewage [9][10][11], susceptibility to densification and dewatering. These properties are notably related with the morphology of sludge flocks as well as with their diameters [9][10][11][12][13]. The species composition of an active sludge organisms may also inform about possible malfunction of wastewater treatment plant biological part [3,5,14,15]. A safe use of dewatered sewage sludge, for example for agricultural application or recultivation of degraded areas, also depends on presence of heavy metals [16][17][18] and pathogenic organisms [19][20][21].Particle diameter measurements can be conducted in many ways, and the most basic and the first to be applied were the microscope observation methods [11,12,22,23]. Neis and Tiehm used, among others, the membrane filtration method. The examples of other
The article presents the relations between the saprobic index S as well as the biocenosis structure indices and BOD 5 , the latter being the main parameter of the wastewater quality. Estimation was carried out for the essential indices: saprobic index S, taxon richness ⌬ Sr (⌬ * ), Shannon-Wiener index H (H * ), evenness index V (V * ), MacArthur's index E (E * ) and "proportionality" index P (P * ), calculated for saprobes present in wastewater with different levels of pollution (characterized by BOD 5 values). For the calculation of the above mentioned indices, numbers and abundances of species (indices without asterisk) as well as the numbers and abundances of easily identified morphological-functional groups (indices with asterisk) were used. To determine the dependences between the indices and BOD 5 , an analysis of correlation was carried out. Results showed that: (i) the value of BOD 5 for treated (or self-purified) wastewater can be assessed most accurately by using index E * -a slightly less precise evaluation of this parameter can be obtained on the basis of indices: H * , S, and H; (ii) bioindication based on biocenosis structure indices (E * , H, * and H) gives results comparable to and even more accurate than those obtained with the use of the saprobic index S; (iii) bioindication can be based on counting individuals (without assigning them to a species) in groups easily differentiated by well-observed morphological features.
The article presents the possible methods for determining biological or statistically significant differences between taxocenoses compared with respect to biodiversity. To obtain a complete description of biological differences between the compared hypothetical communities, the following indices were calculated: S (taxon richness), H (the Shannon index), Hmax (the maximum value of the Shannon index for the richness of taxa represented by the same number of individuals), Vd (a percentage value of covering the structural capacity of community, “evenness deficiency”), E (the MacArthur index - a taxon number (S) in a community for which the observed value of H equals Hmax), and Ps (a taxon richness shortage in percents). Moreover, a graphic profile method (Дд, Tj, and Lj profiles) was used for comparing the diversity of the communities. To obtain information about statistically significant differences in biodiversity between the analysed communities, rarefaction curves were applied. The curves are based on the null models and the Monte Carlo method. The rarefaction method resulted in determination of the statistical significance of the differences between taxon richness and Shannon's index values for the compared communities. The Vd and Ps indices and the profile method allowed concluding about the significance of the biological differences between taxocenoses, even when their values of Shannon's H indices were numerically similar.
The effect of ion-exchange substrate Biona-312 additions to nickel (Ni)-polluted soil on yield and mineral composition of cherry tomato and cucumber was evaluated. The plants were grown on the following media: untreated soil (the control series) and soil with added Ni (40 and 100 mg of Ni kg 21 , respectively) as well as Biona-312 (2 and 5% mass additions, respectively). In the presence of 40 mg of Ni kg 21 of soil, the plant yield did not change significantly, whereas in conditions of 100 of mg Ni kg 21 , it decreased significantly. Biona-312 application on Ni-polluted soil increased the productivity of both species. The content of macronutrients in the plant biomass varied depending on the growth stage, Ni level, and Biona-312 dose. For both species, higher Ni content was observed in the aboveground organs than in roots, but tomato contained more Ni than cucumber. Biona application reduced the Ni content in plant biomass of both species after being introduced into soil with a higher Ni level.
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