Design, manufacturing, and field-application of a new coarse-screen system

Various products such as toilet papers and moist wipes are disposed of into wastewater collection systems. Such solids mix with other wastewater constituents such as grease to form impediments in sewer pipes. Similarly, various retailers (e.g., restaurants, catering facilities, mechanical shops) may discharge solid wastes such as food waste and wet wipes into sewer systems. As a result, large size sewer solids accumulate and cause blockages within sewer systems and at wastewater treatment facilities. At wastewater treatment plants, coarse screens, fine screens, and grinders are used commonly to ensure that large debris is removed from wastewater. However, large debris such as wipes also clog and disable treatment units as screens. A key reason for this problem are the variations in size ranges (2-20 cm) of solids that are captured by coarse screens. While bar-openings of coarse screens are about 2-3 cm, sizes of waste solids that approach to screens can be around 20 cm, and can clog screens rapidly. To minimize such problems, this study proposes to design series of coarse screens with bar-openings decreasing gradually (e.g., 10, 5, and 2 cm). Accordingly, this new system can remove very large solids (10-20 cm), large solids (5-10 cm), and coarse solids (2-5 cm), correspondingly. In this context, this study presents this adaptation strategy for a local treatment plant. we designed and manufactured a new coarse screen that was installed and tested for its performance at a real-life facility. We examined impat of the new system by tracking maintenance needs (failure and repairs) of coarse screens before and after the installation. In general, the new screen enhanced treatment performance, while it reduced maintenance problems significantly. The study concludes that similar strategies and applications must be developed and implemented for municipal wastewater treatment plants to protect physical treatment units, and municipal funds. Keywords: Wastewater treatment, screens, seperation, sewer solids