Designing and Modeling of a Municipal Wastewater Treatment Plant With GPS-X

Wastewater treatment is the process used to remove contaminants from wastewater to produce an effluent suitable for discharge to the environment. Several kinds of wastewater are treated based on the concentration of various parameters. Domestic Wastewater/Municipal Wastewater is treated in Sewage Treatment Plants (STP), which involve various types of processes like physical, chemical and biological to treat the wastewater better. The treatment plant involves five steps of the process – preliminary treatment, primary treatment, secondary treatment, tertiary treatment and sludge treatment to meet the safe disposal guidelines of the department of the environment. In this paper, a municipal wastewater treatment plant for Uttara City is designed and modeled with GPS-X. GPS-X is a wastewater treatment plant modeling software package that is used for verify the treatment process. The design calculation of all unit operations is shown with a specification table. The Process Flow Diagram (PFD), Process Block Diagram (PBD) and mass balance of the process are expressed in the article. The design calculation of the STP is performed with a steady-state process. After each unit operation, the concentration of various parameters – TSS, BOD, VSS, TN is analyzed and the removal efficiency for different equipment is calculated. The STP is designed to maintain the guidelines of the Department of Environment, Bangladesh. At the end of the paper, the designing and modeling steps of a sewage treatment plant will be pursued. Finally, some recommendations are done in the conclusion section.

Characterisation of Microplastics from the Effluent of a Municipal Wastewater Treatment Plant and from its Natural Receptor

Results obtained from the characterization of three water samples (one representing the effluent of a municipal treatment plant and the two others representing surface water from the Jiu River/Romania, upstream and downstream of the effluent discharge point) are presented in this study in terms of microplastic content. The water samples were processed by successively passing them through a series of filters with the following dimensions: 5 mm, 0.5 mm (500 im), 0.1 mm (100 im) and then through some microfiltration membranes (MF) type EZ-Pak Membrane Filters (Merk-Millipore) made of a mixture of cellulose esters, with an average pore diameter of 0.45�m. In order to highlight the microplastics in the water samples, their analysis was performed as well as the solid material retained on the microfiltration membranes, by scanning electron microscopy (SEM) using a SEM Quanta FEG 250/Thermo Fischer Scientific. The results obtained highlighted the existence of microplastics in all the analyzed samples, in the known forms presented in the specialized literature: irregular planes, fibers and spheres. Their dimensions are variable, ranging between 3.2 �m and 119.5 �m for irregular plane microplastics and between 3 �m and 15 �m for spherical microplastics. The dimensions of microplastics in the form of fibers are also in the range of tens of �m and cannot be established exactly because in most cases they appear in the form of conglomerates. The treatment plant�s microplastic effluents content led to the modification of the physical-chemical indicators of the water in their natural receptor. Thus, the content of organic matter and total suspended matter in the downstream water compared to the effluent discharge point is higher than in the upstream water. The analysis of microplastics by SEM allows only their highlighting and their geometry, being a first step in the study of the pollution induced by such materials.