The objective of this study was to model the operation of a vertical-flow constructed wetland (VF-CW) for domestic wastewater, using Monte-Carlo simulations and selected probability distributions of various random variables. The analysis was based on collected wastewater quality data, including the values of the pollutant indicators BOD₅ (biochemical oxygen demand), COD_Cr (chemical oxygen demand), and TSS (total suspended solids), in the 2017–2020 period. Anderson–Darling (A–D) statistics were applied to assess the fit of the theoretical distributions to the empirical distributions of the random variables under study. The selection of the best-fitting statistical distributions was determined using the percentage deviation (PBIAS) criterion. Based on the analyses that were performed, the best-fitting statistical distributions for the pollution indicators of the raw wastewater were the generalised extreme value distribution for BOD₅, the Gaussian distribution for COD_Cr, and the log-normal distribution for TSS. For treated effluent, the log-normal distribution was the best fit for BOD₅ and COD_Cr; the semi-normal distribution, for TSS. The new data generated using the Monte-Carlo method allowed the reliability of the VF-CW operation to be assessed by determining the reliability indices, i.e., the average efficiency of the removal of pollutants (η), the technological efficiency index (R), the reliability index (CR), and the risk index of the negative control of the sewage treatment plant operation (Re). The obtained results indicate that only in the case of COD_Cr, the analysed treatment facility may fail to meet the requirements related to the reduction of organic pollutants to the required level, which is evidenced by the values of the indicators CR = 1.10, R = 0.49, and η = 0.82. In addition, the risk index of the negative operation of the facility (Re) assumes a value of 1, which indicates that during the period of its operation, the VF-CW system will not operate with the required efficiency in relation to this indicator. The novelty of this work is the implementation of the indicated mathematical simulation methods for analysing the reliability of the operation of the domestic wastewater treatment facility.

The aim of the study was to analyze the mean daily wastewater load from the corporate wastewater treatment plant in Nowy Targ. The study analyzed the wastewater load expressed by BOD₅, COD, total nitrogen (N_tot), total phosphorus (P_tot) and chromium ions (Cr). The study was conducted from 2006 to 2016, in which 591 samples of raw wastewater were collected and analyzed in a control well before the treatment plant with a mean of 4 times a month. The scope of research in the analytical part covered the variability of wastewater loads in individual years and determined the characteristic values of mean daily load in particular months. Mean daily wastewater load for BOD₅ – 7 053 kg·d⁻¹ for COD – 23 437 kg·d⁻¹ for total nitrogen – 1 464 kg·d⁻¹ for total phosphorus – 197 kg·d⁻¹ and for chromium ions – 129 kg·d⁻¹. For each of the analyzed index, it was found that in the each months mean daily wastewater load in raw wastewater is variable. In the analyzed period the mean daily discharged wastewater oscillated within 13 924 m³·d⁻¹, which accounted for about 66% of the projected load.

The aim was to assess the stability of the chemical composition of the groundwater in terms of maintaining the status of therapeutic waters in accordance with the Geological and Mining Law in Poland. The basis for the analysis was the results of stationary observations for nine hydrogeological wells for the needs of the Mineral Water Bottling Plant “Piwniczanka”. The database used for the analysis covered the years 2008–2018 and concerned the content of selected ions as well as total dissolved solids and CO₂ content. For each of the analyzed boreholes, the analysis of the variability of the content was performed using graphical Schoeller–Berkaloff plots and statistical investigations (GWSDAT and STATISTICA). This hydrogeochemical investigation has demonstrated that groundwater in the Piwniczna area occur as natural “carbonated waters” and “waters containing carbon dioxide”. Summing up the analysis, it can be stated that the content of basic ions of the exploited water show a small variability and does not threaten the loss of therapeutic water status for seven of the boreholes. Two of them have a little risk of loss of therapeutic water status. Variable content of sodium ions causes changes in the hydrogeochemical type of water without affecting the maintenance of the status.

This paper present analysis and evaluation of the impact of clean sewage on the water in river Mordarka, in the period 2012-2015. The analysis conducted based on collected and statistical research: amount and composition of purified sewage discharged to the receiver. The following pollution index...

The aim of study was the analyze of the reliability pollution removal in wastewater treatment plant in Mińsk Mazowiecki. The article presents the results of the reliability of BOD, COD and total suspended solids removal of wastewater treatment plant with actived sludge. Physical and chemical analyses of raw wastewater and treated effluent were carried out in the years 2016–2017 (2 years). The designed size of the treatment plant with actived sludge, expressed in PE is 82 200 residents. During this study period, 50 wastewater samples were collected and analyses. For each of pollution indicators descriptive statistic, percentage reduction and and treatment plant reliability factors (WN) were calculated. The average effectiveness of BOD5 (Biochemical Oxygen Demand), COD_Cr(Chemical Oxygen Demand) and TSS (Total Suspended Solid) removal in this period of study were respectively: 99.1%, 96.3% and 98.9%. A reliability analysis was performed using the Weibull probability model.

The purpose of this work was to determine the optimal percentage of wastewater from cesspool in the mixture of wastes subjected to treatment processes, which will not have a negative impact on the functioning of the collective treatment plant. The study was carried out over a period of two years, with 48 samples of wastewater flowing in from the sewage network and delivered with the slurry tanker collected and subjected to physical and chemical analysis. The analysis included: Biochemical Oxygen Demand (BOD₅), Chemical Oxygen Demand (COD), and Total Nitrogen (TN). In addition, the study defined the daily balance of the amount of inflowing and transported wastewater. Based on the analysis carried out, it was found that the unit loads of BOD₅, COD and TN in the mixture of wastewater subjected to the treatment process will be at the level of loads assumed in the project, when the share of supplied wastewater, i.e., from cesspool, will be at the level of 5% of the total amount of wastewater. Considering that in the analysed period the total average daily amount of wastewater subjected to the treatment process was 253.5 m³·d⁻¹, the optimal amount of wastewater delivered should be 12.7 m³ in each day of the week.