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The changes of nitrogen content during sewage treatment : A study of a two-stages wastewater treatment plant

Młyńska Anna, Chmielowski Krzysztof

Journal of Water and Land Development

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2024

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no. 61

106--114

EN

The paper relates to the changes in the content of various nitrogen forms, i.e. total nitrogen (TN), Kjeldahl nitrogen (TKN), ammonium nitrogen (NH4-N), nitrite nitrogen (NO2-N), nitrate nitrogen (NO3-N) and organic nitrogen (ON) at the subsequent operation stages of a mechanical-biological wastewater treatment plant (WWTP). The obtained results indicate the correctness of nitrogen compounds transformations at the subsequent stages of sewage treatment; they are considered as typical for two-stages WWTPs, operating in the activated sludge technology. The analysis of multi-year data and the analysis for particular months show that nitrogen compounds in the form of NO3-N and NO2-N, were characterised by the greatest variability. Both the classical analysis of the nitrogen compounds content in each month of the year and the analysis using control cards prove that in the months characterised by a low temperature or by the impact of meltwater or rainwater, disturbances in the nitrification and denitrification processes can be expected, and thus, lower efficiency of nitrogen removal (winter months, the period between winter and spring, summer months). Knowledge on the transformation of nitrogen compounds at the subsequent stages of treatment can be useful both to improve the efficiency of the currently used processes and to model new solutions, which is particularly important in the case of biogenic compounds reduction.

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Research on the Hourly Water Consumption Structure in Rural and Suburban Household

Młyńska Anna, Bergel Tomasz

Journal of Ecological Engineering

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2022

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Vol. 23, nr 9

219--230

EN

Currently, the character of many households located in rural areas is closer to that of suburban households. The change in the characters of households located in rural areas results in changes in the size and irregularity of water demand, which should translate into a new approach at the stage of water supply systems designing. Therefore, in order to supplement the state of knowledge in this study area, this paper presents the results of the research on the structure of hourly water consumption in two households located in rural areas; the first household had a suburban character, whereas the second one was a typical rural household. The results showed differences in the amount and the distribution of hourly water consumption in the analyzed households. Except on weekends, the average hourly water consumption in rural household (RH) was higher than in suburban household (SH). In contrast, in the rural household, the distribution of hourly water consumption on all days of the week was very similar and the peak water consumption was clearly marking in the morning and in the evening. In the case of the suburban household, a tendency of increased water consumption in the evening was observed, but without clearly noticeable peak water consumption. Moreover, the structure of hourly water consumption in suburban household on Saturday and Sunday was different than on weekdays. The analyzed households were characterized by the highest share of hourly water consumption up to 20.0 dm3·h-1. In the rural household, both the amount and the distribution of hourly water consumption were determined by water use for additional purposes. In the case of the suburban household, it was shaped by the living needs of the inhabitants.

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Analysis of the Hydraulic Load of a Local WWTP in the South-Eastern Poland Including Hydraulic Capacity of the Sewage Receiver

Młyńska Anna, Młyński Dariusz, Chmielowski Krzysztof

Journal of Ecological Engineering

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2022

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Vol. 23, nr 11

261--272

EN

The paper constitutes the analysis of hydraulic load of a local wastewater treatment plant in the south-eastern Poland along with the analysis of sewage receiver hydraulic capacity and related receiving waters protection. Assuming that the daily outflow of treated sewage should not exceed 10% of the mean-low flow (SNQ) of the receiver, no case of daily sewage outflow greater than 10%·SNQ = 51 840 m3·d-1 was recorded. Moreover, average daily hydraulic load of the treatment plant was lower than the limit value by over 70% and the maximum recorded value – by over 40%. Furthermore, the conducted analysis shows that the particular months differed from each other in the values of the daily hydraulic load of the wastewater treatment plant at the outflow; May was the month with the highest average daily sewage outflow, while September was characterized by the lowest average daily outflow of treated sewage. There was also no clear dependence between the hydraulic load of the WWTP and the day of the week. Daily sewage outflows ranging from 10 000 m3·d-1 to 12 000 m3·d-1 constituted the largest part of all observations. The daily sewage outflows directed to the receiver prove that there is no threat to the preservation of the water environment quality.

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Effect of internal polyurethane coatings of cast iron pipes on the quality of transported potable water

Zielina Michał, Młyńska Anna

Environment Protection Engineering

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2022

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Vol. 48, nr 3

25--38

EN

The paper presents the results of laboratory tests to determine the effect of an internal polyurethane coating in ductile iron pipes on the quality of disinfected and non-disinfected drinking water. A decrease in the pH of water in contact with the polyurethane coating was found, which was slightly higher in the non-disinfected water than in the disinfected water. The coefficient of variation (CV) of the pH values for the chlorinated water samples was 5.02% and for the non-chlorinated water was 7.15%. The experiments also showed a rather large effect of polyurethane liner on the increase of TOC concentration in water. The presence of disinfectant further slightly increased the amount of organic compounds released. The CV values normalized to one day for TOC were as high as 193.32% and even 199.39% for disinfected water. A significant effect of polyurethane coating was observed on the color change and odor of water. On the other hand, there was no effect of polyurethane coating on alkalinity and chlorine consumption in water. The CV values normalized to one day in both cases were very small at 0.97% and 0.53%, respectively.

5

A New Approach to the Maximum Quarterly Water Consumption Modeling on the Example of Individual Water Consumers in a Small Water Supply System

Młyńska Anna, Bergel Tomasz, Młyński Dariusz

Rocznik Ochrona Środowiska

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2021

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Tom 23

180--197

EN

Quarterly water consumption data collected in a small water supply system were used for elaboration of a new water consumption modeling approach. In this paper, multi-distribution statistical analysis was performed. As the Anderson-Darling test proved, at least a half out of the ten tested theoretical probability distributions can be used for description of the water consumption. The application of the PWRMSE criterion made it possible to determine, which of the tested theoretical distributions is the best-fitted to the empirical data set. In the case of total daily water consumption for the group of the households, it was Johnson distribution, whereas for the average daily water consumption per capita, it was GEV distribution. Based on the best-fitted probability distribution, a 25-year water consumption simulation with the Monte Carlo method was conducted. Because methodology of this study is based on the probability distributions, even if the type of theoretical distribution of the water consumption will change, it will be still possible to use this simulation method by assuming the other distribution.

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Analysis of the Impact of the Air Temperature on Water Consumption for Household Purposes in Rural Households

Bergel Tomasz, Młyńska Anna

Journal of Ecological Engineering

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2021

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Vol. 22, nr 3

289--302

EN

The paper presents a research hypothesis assumed that the air temperature affects the amount of the water consumption per capita for household purposes (indoor water use). Investigations were conducted based on daily water meter readings of several rural households located in Mszana Górna and Włostowice (Southern Poland). Owing to the double water consumption metering, it was possible to determine the daily water consumption in households, separately for household purposes and for additional purposes. In the performed analysis, the correlation between the average daily air temperature and daily water consumption per capita was tested. For this purpose, correlation coefficients were determined and a 95% confidence interval was assumed. The obtained results showed lack of a clear dependence between the tested variables. Depending on the household, correlation coefficients indicate the existence of a correlation from slight, by weak to moderate. In addition, it was tested that the growth of the air temperature by 1°C caused an increase of the water consumption per capita in the range of 0.14 dm3•d-1•C-1•°C-1 and 1.17 dm3•d-1•C-1•°C-1 (Mszana Górna) and 0.41 dm3•d-1•C-1•°C-1 and 1.78 dm3•d-1•C-1•°C-1 (Włostowice). It can be concluded that often rapid growth of the water consumption in households in spring and summer season and the term of “water consumption per capita” used in this case, primarily concern greater water demand for additional purposes, not for residents’ household purposes.