The aim of the study was to model the operation of a wastewater treatment plant using the Monte Carlo method and selected probability distributions of random variables. Pollutant indices in treated wastewater were analysed, such as: biological oxygen demand ( BOD ₅), chemical oxygen demand ( COD _Cr), total suspended solids ( TSS), total nitrogen (N _tot), total phosphorus (P _tot). The preliminary analysis of pollution indicators series included the: calculation of descriptive statistics and assessment of biological degradability of wastewater. The consistency of the theoretical distributions with the empirical ones was assessed using Anderson–Darling statistics. The best-fitting statistical distributions were selected using the percent bias criterion. Based on the calculations performed, it was found that the analysed indicators of pollution in treated wastewater were characterised by an average variability of composition for BOD ₅, COD _Cr and TSS, and a high variability of composition for N _tot and P _tot. The best fitted distribution was log-normal for BOD ₅, TSS, N _tot and P _tot and general extreme values for COD _Cr. The simulation carried out using the Monte-Carlo method confirmed that there may be problems associated with the reduction of nutrients (N _tot and P _tot) the analysed wastewater treatment plant. Results of values obtained of the risk values of negative control of wastewater treatment plant operation for biogenic compounds, different from 1, indicate that the number of exceedances at the outflow may be higher than the acceptable one.

The river system of the Bengal delta encompasses a huge amount of fluvial sand; however, no comprehensive studies were available on using this river sand in foundry industries. Hence, the present research evaluates the foundry properties of trans-boundary Brahmaputra River sand and its prospects for use in foundries. Several laboratory analyses have been performed to elicit the foundry properties using standard methods of foundry analysis, including XRD, XRF, TG-DSC, and FESEM. From the study, the sand contains mainly quartz with small amounts of feldspar, amphibole, chlorite, and mica, and exhibits a subangular to subrounded shape. The sand is dominated by SiO2 (67.81–69.97%) and lesser amounts of other oxides, and it is thermally stable within 1000 °C temperature. The grain fineness number (64–79), mineralogical, chemical, thermal, and foundry properties are suitable for non-ferrous metal casting without distortion. Further, the aluminum and zinc alloy casting with trials demonstrate their potential for use in the foundry industries. The outcomes of this study thus offer valuable information about utilizing Brahmaputra River sand for foundry applications.