جستجوی مقالات مرتبط با کلیدواژه « sewerage » در نشریات گروه « آب و خاک »

Millions of dollars are being spent worldwide on the repair and maintenance of sewer networks and wastewater treatment plants every year. The production and emission of hydrogen Sulfide has been identified as a major cause of corrosion and odor problems in sewer networks. Prediction of hydrogen sulfide production in the sewer system helps the engineers and manager to obtain a proper strategy for their optimal management and for an analysis of reassurance. The purpose of this study is to review the selected models of predicting sulfide generation in sewerage that in this study the Equations of predicting sulfide generation are discussed. The status of any operational sewerage can be assessed, and the critical points can be recognized by using such equations. The results of this research show that sulfide buildup in sewerage is a function of hydraulic characteristics and qualitative. In most of the proposed models in this study the density of organic materials (BOD & COD) was considered as the main parameter in determining the amount of hydrogen sulfide creation in sewerage. It is notable that ORP and pH can also be used as an index in assessing sulfide creation in sewerage systems. Real time Decision-making is of great importance in the operationalization and management of the sewerage systems; therefore, the COD-based and BOD- based models are mostly suitable for technical studies and ORP-based models are of prime importance for operationalization. Finally, a study conducted in west of Mashhad on the accurate models show that Boon, Nielsen and Hvitved models provide a better prediction as compared with other models that used in this paper.

Sulfide production has been one of the most important problems in sewage collection systems that came to be known as an important factor of corrosion in concrete sewerage systems since early 1900. The emission of hydrogen sulfide gas in sewerage conduits creates problems including biological corrosion of concrete, release of repulsive odors in the city environment, as well as the potential danger that the toxic sulfide gas poses for the workers. Several factors such as high sulfate density, the organic material, temperature, waste water retention period, pH, Oxidation reduction potential (ORP), flow rate and surface area can increase the probable emission of sulfide. Due to the adverse effects of this chemical material, in recent years broader studies have been conducted on the control of sulfide production in sewage collection networks, including the injection of air, nitrate, H2O2, and iron salt. The purpose of these studies was to find suitable solutions for controlling the emission of hydrogen sulfide taking into account the construction conditions and economic profitability. This article is a review of all the research done on controlling the production of sulfate in sewage collection systems. It also reviews the advantages and disadvantages of the methods used in these studies which have examined the effectiveness of using formaldehyde, MgO2/CaO2, MFCs, nitrates, microbe-eliminators. The results of this study show that using the aforementioned chemical and biological materials for controlling the challenges of hydrogen sulfide production in sewerage, besides being economical and effective, are able to protect sewerage from corrosion and we can also arrive at a healthy and odorless environment.