Operational problems of wastewater collection systems and proposed solutions

Hygenic products such as toilet papers and moist wipes that are disposed of into wastewater collection systems blend with other wastes such as fat, oil, and sand, and subsequently, accumulate in sewer pipes. Physical characteristics of such waste mixtures (e.g., mass, volume, density) increase due to blending to hinder their movement in critical parts of sewer systems such as pipes with low-slope, and elbows, where they accumulate and cause blockages. As a result of sewer overflows, residents face property damage, financial costs, and public health threats, while municipalities spend considerable amount of public funds to rectify sewer problems. In this context, this study investigated the main causes of sewer blockages that occur in plumbing systems of buildings and households, as well as, in main sewers (e.g., street pipes and manholes). The study is carried out by conducting field investigations to analyze critical causes of blockages in the metropolitan cities of Sakarya, and Kocaeli, Turkey. The findings are categorized as human errors, construction problems, and in-use issues. Typical example of human errors include inappropriate disposal of solid wastes (e.g. baby diapers) into sewer systems. Construction problems can be typified as insufficient pipe slopes or diameters, while in-use issues include deformation of sewer pipes due to reasons such as tree-root penetration, and heavy traffic load. As potential solutions, two independent prototypes were designed and manufactured to remove solids from wastewater flow. The first product can be installed in household-plumbing systems to capture nonflushable hygienic products that are improperly disposed of into the system. The second product is a small scale grit chamber that can be placed in rain-water collection channels, where the grit chamber seperates sand and clay from rain-water before reaching sewer system. Each product was designed and improved in light of discussions with managers and engineers of Sakarya Water and Wastewater Authority. Keywords: wastewater collection, sewer systems, pipe clogs, physical disintegration,