Continuous thickening of activated sludge by electro-flotation

The present study was conducted for thickening of activated sludge by continuous electro-flotation (EF) process. The effects of some key factors such as initial pH, current density, operating time, electrode type (stainless steel and graphite) and operation conditions on the sludge thickening by determine of sludge volume reduction (SVR) and sludge solid concentration (SSC) and as well as removal of chemical oxygen demand (COD), total solids (TS), total suspended solids (TSS) and color were investigated. The results showed that the process has a good efficiency. The highest amount of SVR efficiency (89.3) and SSC (38 g L-1) were achieved at current density of 8 mA cm(-2) in 15 min for stainless steel. Moreover, as surface/volume ratio increased, better thickening happened because increases both mass transfer and electro-generation of O-2 and H-2 at the surface of electrodes in low applied current density. Accordingly, consumed electrical energy was 0.15-1 kW h m(-3). Although suitable cell design is entirely essential, the use of chemicals and temperature increase are not effective. Consequently, EF is a comparatively appropriate process for thickening; in the water separated from the process, the amounts pertaining to COD, TS, TSS and color were respectively 112, 1601, 140 mg L-1 and 5 TCU which are useable for subsequent different consumptions. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved

Municipal solid waste management during COVID-19 pandemic: a comparison between the current activities and guidelines

The COVID-19 pandemic has affected everyone�s lifestyle and this has resulted in a change in the quantity and composition of municipal solid wastes. Moreover, the post-pandemic waste management is very important as a bad management may lead to the more spread of the disease. The objective of this study was to evaluate the application of guidelines presented for the era of the COVID-19 pandemic in proper solid waste management. To this end, the data were collected by using interviews and field researches and then the obtained data were compared with the international guidelines presented by international organizations. By investigating the municipal waste management during this pandemic and its changes compared to pre-COVID-19, coordination of the plans with the guidelines was investigated. The activities of storage, collection, transportation, recycling, final landfill, as well as the observation of the health instructions by staff and informal sections were assessed in the current research. Although the results showed that the situation was satisfactory in the sections like health and safety of waste management operators due to the existence of protocols and general educations, the waste management plans have not been changed much from before the epidemic of the Coronavirus. The absence of a national policy and plan for waste management in the era of a pandemic and ignoring the guidelines developed by other countries and organizations were observable. Therefore, the codification of new policies for municipal waste management during an epidemic is necessary. © 2021, Springer Nature Switzerland AG

Study of littered wastes in different urban land-uses: An 6 environmental status assessment

Littered waste is a severe environmental problem. Although there have been many studies on wastes littered in the environments like beaches and seas, there is insufficient information on littered wastes in the urban settings. In this research, employing visual survey by the field litter counts method, littered wastes in six urban land uses in Qazvin, Iran were studied. The results showed that administrative and recreational land uses, by an average of 5.22 and 9.59 items per 100 m, respectively, had the lowest pollution, while low-density commercial land use had the maximum pollution by 185.96 items per 100 m. Urban littered waste ratios were not the same in various land uses: cigarette waste and paper and cardboard accounted for higher than 80 of the whole littered wastes in most studied land uses. The cigarette butt was also the most frequently litter in the city. In terms of environmental status, administrative and recreational areas can be defined as places with good conditions, while low-density commercial land use had bad conditions. Consequently, urban land use was acknowledged as a significant factor in the density of littered waste. More attention to cleaning the commercial land use to reduce the density of littered waste, and also finding methods to decrease littering waste by citizens, is a need in urban environment. © 2020, Springer Nature Switzerland AG

Set-valued orthogonal additivity

We study the set-valued Cauchy equation postulated for orthogonal vectors. We give its general solution as well as we look for selections of functions satisfying the equation

Set optimization - a rather short introduction

Recent developments in set optimization are surveyed and extended including various set relations as well as fundamental constructions of a convex analysis for set- and vector-valued functions, and duality for set optimization problems. Extensive sections with bibliographical comments summarize the state of the art. Applications to vector optimization and financial risk measures are discussed along with algorithmic approaches to set optimization problems

Orthogonalities and functional equations

In this survey we show how various notions of orthogonality appear in the theory of functional equations. After introducing some orthogonality relations, we give examples of functional equations postulated for orthogonal vectors only. We show their solutions as well as some applications. Then we discuss the problem of stability of some of them considering various aspects of the problem. In the sequel, we mention the orthogonality equation and the problem of preserving orthogonality. Last, but not least, in addition to presenting results, we state some open problems concerning these topics. Taking into account the big amount of results concerning functional equations postulated for orthogonal vectors which have appeared in the literature during the last decades, we restrict ourselves to the most classical equations

Estrogen- and Progesterone (P4)-Mediated Epigenetic Modifications of Endometrial Stromal Cells (EnSCs) and/or Mesenchymal Stem/Stromal Cells (MSCs) in the Etiopathogenesis of Endometriosis

Endometriosis is a common chronic inflammatory condition in which endometrial tissue appears outside the uterine cavity. Because ectopic endometriosis cells express both estrogen and progesterone (P4) receptors, they grow and undergo cyclic proliferation and breakdown similar to the endometrium. This debilitating gynecological disease affects up to 15% of reproductive aged women. Despite many years of research, the etiopathogenesis of endometrial lesions remains unclear. Retrograde transport of the viable menstrual endometrial cells with retained ability for attachment within the pelvic cavity, proliferation, differentiation and subsequent invasion into the surrounding tissue constitutes the rationale for widely accepted implantation theory. Accordingly, the most abundant cells in the endometrium are endometrial stromal cells (EnSCs). These cells constitute a particular population with clonogenic activity that resembles properties of mesenchymal stem/stromal cells (MSCs). Thus, a significant role of stem cell-based dysfunction in formation of the initial endometrial lesions is suspected. There is increasing evidence that the role of epigenetic mechanisms and processes in endometriosis have been underestimated. The importance of excess estrogen exposure and P4 resistance in epigenetic homeostasis failure in the endometrial/endometriotic tissue are crucial. Epigenetic alterations regarding transcription factors of estrogen and P4 signaling pathways in MSCs are robust in endometriotic tissue. Thus, perspectives for the future may include MSCs and EnSCs as the targets of epigenetic therapies in the prevention and treatment of endometriosis. Here, we reviewed the current known changes in the epigenetic background of EnSCs and MSCs due to estrogen/P4 imbalances in the context of etiopathogenesis of endometriosis

Modeling of electrolysis process in wastewater treatment using different types of neural networks

Indirect electrolysis has been used for the removal of chlorophyll a (as indicator of algae) from the final effluent of aerated lagoons in the wastewater treatment plant of Bu-Ali Industrial Estate. The efficiency of the process was studied experimentally and by simulation using neural networks. The process analysis was done in different conditions of retention time (5-50 min) and using two types of electrodes based on aluminum and stainless steel, with different distances between electrodes (from 1.0 to 3.5 cm). The electrical current and the average voltage applied were between 5 and 90A (0.74-12A dm(-3)) and 50 V. respectively. The influence of the main parameters of the electrolysis process on the final values for chlorophyll a, TSS and COD is evaluated experimentally. On the other hand, predictions of the main system outputs of a treated waste as a function of initial characteristics (initial values of chlorophyll a, TSS, COD) and operation conditions (temperature, electric power, time, electrode distance, and electrode type) were performed using artificial neural networks. The modeling methodologies elaborated in this paper are based on different types of neural networks, used individually or aggregated in stacks. They were developed gradually in the sense of improving the model performance. The neural network results represent accurate predictions, useful for experimental practice. (C) 2011 Elsevier B.V. All rights reserved

Catalytic ozonation of phenol using copper coated pumice and zeolite as catalysts

Background: Catalytic ozonation has recently been applied as a new method of contaminant re- moval from water and wastewater. In this study, copper coated pumice and zeolite were used to catalyze the ozonation of phenol as a target pollutant from aqueous solutions. Methods: The pumice and zeolite stone were modified by CuSO4 (1N). Modified pumice and zeo- lite were characterized by Adsorption/Desorption Porosimetry (BET) and Scanning Electron Micro- scope analyses. Ozonation and catalytic ozonation experiments were performed in a 1 L semi- batch reactor containing a prepared phenol solution. The efficiency of catalytic ozonation was in- vestigated by different variables: pH value, contact time, initial phenol concentration, catalyst dose, and radical scavenger. Results: Experimental data indicated that as the pH solution increased, phenol removal in- creased. pH = 8 was measured as the optimum pH. The removal efficiency in single ozonation process (SOP) was 32 and in the catalytic ozonation process (COP) using modified zeolite and pumice was 51 and 63, respectively. Moreover, these processes showed a great ability to min- eralize phenol (up to 30). Using the radical scavenger determined the indirect oxidation as the main pathway of phenol removal in both catalytic processes. Conclusion: The copper modified zeolite and pumice had good performance to remove phenol through catalytic ozonation method