It can be helpful to quickly estimate solids production in wastewater. Certainly, each wastewater treatment plant and its collection system, with variable ratios of domestic, commercial, and industrial flow contributions, is going to be unique regarding its specific wastewater characterization. But for those situations where you don’t have plant operating data you can use more general estimates to begin an analysis. The information provided below is quoted from an excellent, highly recommended, textbook called “Wastewater Sludge Processing” written by Izrail S. Turovskiy and P.K. Mathai. This text is loaded with informative data, tables, graphs, and diagrams. If you click on the book cover graphic you can download a PDF file showing the table of contents.
Determining the quantity of sludge produced in the treatment of wastewater is required for the sizing of sludge processing units and equipment such as sludge pumps, storage tanks, thickeners, digesters, and incinerators. Generally, solids production rates range between 0.2 and 0.3 kg/m3 (0.8 to 1.2 dry tons/MG) of wastewater treated. In the absence of historic or plant-specific data, a rule-of-thumb approximation for solids produced in a typical wastewater treatment plant is 0.24 kg/m3 (1 dry ton/MG) of wastewater treated (WEF, 1998).
Screenings include relatively large debris, such as rags, plastics, cans, leaves, and similar items that are typically removed by bar screens. Quantities of screenings vary from 4 to 40 mL/m3 (0.5 to 5 ft3/MG) of wastewater. The higher quantities are attributable to wastes from correctional institutions, restaurants, and some food-processing industries. Screenings are normally hauled to a landfill.