Tag: chemical
Introduction to PC Pump Intake Hydraulics One of the most persistent and expensive failure modes in municipal wastewater treatment plants involves the premature destruction of progressive cavity (PC) pump stators. While often blamed on “bad rubber” or manufacturing defects, a significant percentage of these failures are actually hydraulic issues rooted in the civil and mechanical […]
Introduction One of the most persistent misconceptions in municipal wastewater engineering is that positive displacement (PD) pumps are immune to the hydraulic sensitivities that plague centrifugal systems. While it is true that double disc pumps (DDP) are robust, self-priming, and capable of handling high solids, they remain subject to the fundamental laws of fluid mechanics. […]
Introduction Municipal engineers frequently underestimate the complexity of chemical injection at remote lift stations. While the primary sewage pumps receive the bulk of the design attention, the auxiliary chemical feed systems are often the critical defense against the wastewater industry’s most pervasive enemies: hydrogen sulfide ($H_2S$) corrosion, noxious odors, and Fat, Oil, and Grease (FOG) […]
Introduction Peristaltic pumps (often referred to as hose pumps or tube pumps) are frequently selected for their ability to handle aggressive chemicals, viscous sludge, and shear-sensitive fluids in water and wastewater treatment. However, despite their mechanically simple design—typically involving a rotor compressing a hose—they present a unique set of operational challenges. A surprising industry statistic […]
Introduction One of the costliest errors in municipal wastewater design is the mismatch between pump metallurgy and fluid characteristics. Engineers often default to 316 Stainless Steel for its “universal” corrosion resistance, only to witness premature failure due to abrasive scour in grit-heavy sludge applications. Conversely, specifying standard Grey Cast Iron for septic receiving stations can […]
Introduction The failure of a chemical feed system or sludge transfer unit in a water treatment plant often isn’t caused by a defective pump; it is caused by a failure in the commissioning process. In municipal and industrial applications, up to 60% of early-life equipment failures can be traced back to improper installation, inadequate pipe […]
INTRODUCTION One of the most persistent causes of premature equipment failure in municipal and industrial fluid handling systems is the disconnect between the design point and the actual operating reality. Engineers frequently specify pumps for a peak flow condition that occurs less than 5% of the time, leaving operators to manage equipment that runs inefficiently—and […]
Introduction Sludge digestion remains one of the most volatile and critical unit processes in wastewater treatment. A sour anaerobic digester or a foaming aerobic basin can cost a utility tens of thousands of dollars in chemical buffering, hauled waste fees, and regulatory fines. For design engineers and plant superintendents, the reliability of the “eyes and […]
Introduction In the municipal water and wastewater sector, the “dry pit” is a misnomer that frequently leads to expensive equipment failures. While designed to separate mechanical and electrical equipment from the wet well, dry pits and valve vaults are notoriously hostile environments—characterized by high humidity, potential for accidental flooding, corrosive hydrogen sulfide gases, and confined […]
1) INTRODUCTION In the design of municipal water and wastewater infrastructure, the management of fluid dynamics and headspace containment represents a critical intersection of hydraulics, structural engineering, and environmental control. One of the most frequent trade-off analyses engineers face—particularly in surge control and storage applications—involves choosing between active pressurized containment and passive atmospheric covering. This […]