Filters
Analysis of Sewage Sludge Drying Parameters Using Different Additives
This paper describes the process of drying sewage sludge mixtures with the addition of various components: straw chaff, wood sawdust, ash, bark, wood chips, and walnut shells. The tests were conducted in two series: summer and autumn (with maximum insolation of 24.1 and 29.8 MJâmâ2, respectively). Using a set of sensors with which the experimental station was equipped, the parameters of the environment (temperature, humidity, and insolation) and the parameters of the dried mixtures (temperature and humidity) were measured. Based on the results obtained, the influence of external factors on the parameters, time, and drying effect of the respective mixtures was analyzed. With the initial moisture content of the mixtures ranging from 41 to 79%, a final moisture content of 6 to 49% was obtained, depending on the components and drying conditions. It was found that the drying rate was most influenced by the amount of solar energy and the associated outdoor (maximum 29 °C and 19 °C) and indoor (maximum 33 °C and 24 °C) air temperatures, and in the second series, there was an additional effect of the temperature of the mixtures (maximum 30 °C), upon which the intensity of water evaporation depended. Straw chaff and walnut shells proved to be the best additives, for which the highest drying rates were obtained (max. 50 to 60% humidity drop). The possibility of using dried materials for agricultural and energy purposes was indicated. This approach is in line with the principles of sustainable development.
An Analysis of the Physicochemical and Energy Parameters of Briquettes Manufactured from Sewage Sludge Mixtures and Selected Organic Additives
As a by-product of wastewater treatment, sewage sludge can be used for natural, agricultural, or energy purposes. One method of preparing sludge for management and use is solar drying. To intensify the drying process, natural additives can be used to alter the structure of the sludge and accelerate the evaporation of water. This research aimed to evaluate the influences of different organic additives in sewage sludge mixtures on the physicochemical and energy parameters of briquettes. This research was carried out without thermal boosting in a 4 Ă 2.5 Ă 2 m plastic tunnel. The tunnel was equipped with three drying stations and control and measuring equipment. In two test series, sludge additives in the form of straw and lignocellulosic materials, sawdust, bark, woodchips, and walnut shells, were used. Briquettes were made from the resulting mixtures and then subjected to physical and chemical analyses. This research showed high variability in the contents of trace elements, nitrogen, and sulphur in relation to an increase in the amount of sludge in the briquettes, which, for the briquettes made from sewage sludge, was nearly twice as high as for the briquettes made from the mixtures. The results of the flue gas analysis for the briquettes with sawdust and wood chip additives were very similar. The briquettes made from sewage sludge with lignocellulosic materials (bark and wood chips) had fuel properties similar to woody biomass, with a calorific value and heat of combustion of 15â16 MJ/kg. Fibrous additives (straw) significantly increased the strength parameters of the briquettes, by more than 50% of the value. The compositions and properties of the mixtures affected the following briquetting parameters: temperature and compressive force. The briquettes made from sewage sludge and additives can be classified according to ISO 21640 as SRFs (solid recovered fuels). In most of the results, the net calorific value (NCV) was 3 to 4; the chlorine content (CL) was 2 to 1; and the mercury content (Hg) was 1. The sewage sludge mixtures facilitated the agricultural and energy use of the briquettes.
Nitrogen compounds in effluents from a septic tank
The paper presents the results of long-term studies on the concentrations of total nitrogen and ammonium nitrogen in a septic tank effluent. A statistical analysis concerning the sampling day and the season was performed. The mean concentration of total nitrogen in the effluent was 47±9 g N/m3 and the mean concentration of ammonium nitrogen was 33±11 g N/m3. Results on the cumulative distributions of total nitrogen and ammonium nitrogen in the outflow from the septic tank have also been presented.
The Influence of Drying Sewage Sludge with the Addition of Walnut Shells on Changes in the Parameters and Chemical Composition of the Mixture
Podajnik biokomponentĂłw sypkich, zwĆaszcza do brykieciarek Ćlimakowych oraz peleciarek oraz sposĂłb produkcji brykietu z biokomponentem sypkim
Assessment of the effects of modernization of municipal wastewater treatment plants in Rawicz and KoĆcian
The increase in the standard of living and economic development of cities and smaller settlement units implies the extension and modernization of infrastructure, including wastewater collection and treatment systems, which is closely related to the protection of surface water and groundwater. This study analyzes the effects of the modernization of two wastewater treatment plants carried out between 2019 and 2020. These are the municipal wastewater treatment plants for Rawicz and KoĆcian in the Wielkopolska region. The analysis of contamination indicators and wastewater treatment efficiency showed that in both plants, the modernization and extension of wastewater treatment and sludge treatment technologies resulted in improved treated wastewater parameters and better sludge preparation for use. The high efficiency of contaminant removal (mostly above 94%) improves the standard of living, intensifies care for the environment, and increases the attractiveness of the agglomerations served by the analyzed plants. The obtained results were confirmed by statistical tests.
Chitosan/Perlite System as a Microbial Carrier in Anaerobic Digestion of Food Waste: Characteristics and Impact of the Additive Materials
The article aims to present the results of research on anaerobic digestion (AD) of waste wafers (WF - control) and co-substrate system - waste wafers and cheese (WFC - control), combined with digested sewage sludge. The aim of the study was to evaluate the physicochemical parameters of the chitosan/perlite (Ch/P; 3:1) carrier material and to verify its effect on the directions of change of the bacterial microbiome, removal kinetics of organic matter and AD process efficiency. The experiment was conducted in a laboratory, in a periodical mode of operation of bioreactors, under mesophilic conditions. The results of analyses of morphological-dispersive, spectroscopic, adsorption, thermal and microbiological properties confirmed that the tested carrier material can be an excellent option to implement in biotechnological processes, especially in anaerobic digestion. The microstructural properties of the carrier were influenced by both components: perlite determined the development of the specific surface area, while chitosan shaped the porosity of the system. The thermal properties were determined by the less heat-resistant component, present in a threefold higher weight proportion, i.e. chitosan. The evaluation of quantitative and qualitative changes in the genetic diversity of bacterial communities, carried out using Next Generation Sequencing (NGS), showed that the material has a modifying effect on the bacterial microbiome. Amount of bacteria from phyla Actinobacteria, Bacteroidetes, Campilobacterota, Chloroflexi, Euryarchaeota, Planctomycetes, and Proteobacteria decreased while Firmicutes, Synergistetes, and Thermotogae increased during the course of the experiment. The shapes of the FT-IR spectra indicated a dependence of the degradation rate on both the presence of the carrier and the cosubstrate system. Monitoring of the course of AD was carried out by measuring key parameters for the stability of the process: pH, VFA and VFA/TA ratio (volatile fatty acids/total alkalinity). As a result, an increase in the volume of biogas/methane produced, under the influence of the carrier, was recorded for WF-control by 12.05% and for WFC-control by 19.16%. The volume of methane for the WF-control increased from 351.72 m3 Mg-1 VS to 411.14 m3 Mg-1 VS, while for the cosubstrate sample it increased from 476.84 m3 Mg-1 VS to 518.08 m3 Mg-1 VS, confirming the validity of combining the respective cosubstrate with microbial carrier in anaerobic bioreactor.