Explore content

Numerical modeling was used to test and improve the capacity of existing secondary clarifiers for the City of Longmont, Colorado. The model was used to develop an energy dissipating inlet for a new clarifier and develop modifications that could be retrofit into two existing clarifiers to improve their settling capacity. The existing clarifiers were retrofitted and the plant data showed improved...

Dissolved Air Flotation (DAF) is one of the first unit operations in primary wastewater treatment and is designed to separate suspended solids. In food and beverage applications where clean in place (CIP) is common, large swings in wastewater solids loading, charge demand and pH can occur frequently. Demand for coagulants and flocculants added to aid in DAF solid/liquid separation varies with...

East Bay Municipal Utility District (EBMUD) conducted a pilot study to demonstrate the production and use of biodiesel from interceptor grease waste. Bench-scale testing was followed by pilot-scale production of 200 to 400-L batches. Brown grease with a free fatty acid (FFA) content of 54-100% was obtained from interceptor grease hauled to EBMUD's wastewater treatment plant. Free fatty acids were...

Vibration in mechanical equipment, and especially pumps, is not new or a recent discovery. However, the damage caused by vibration is being recognized and documented more often. Vibration has been brought to the forefront as more facilities are doing condition assessments and determining the root cause of non-performing or marginally performing equipment. Coupled with the technical expertise of engineers trained in the finite-element, modal analysis, and vibration field curriculums plus the sophistication of vibration instruments and equipment, vibration is being recognized in many cases as the root cause and/or symptom of frequent maintenance and equipment rebuilds. Variable-frequency drives have been used in the wastewater industry since the 1980s; however, the implications on pump vibration and natural frequency have been extensively recognized only in the last 15 to 20 years. Several vibration issues are reviewed in this paper.

The integrated control system, a central component of the recently completed Littleton/Englewood Wastewater Treatment Plant's Phase 2 project, was engineered and implemented by Brown and Caldwell to provide value to the owner over the entire life-cycle of the project. The focus on value led to the development of advanced features that provided benefits during project delivery, facility operation,...

 

The 39th Street conduit is the Metropolitan Water Reclamation District of Greater Chicago's (District's) oldest and largest intercepting sewer. The most cost-effective method to rehabilitate the 6.10 meter (20 foot) diameter brick sewer was to complete the project in two phases, limiting service disruption and flooding risk. Phase 1, completed in 2012, consisted of a deep...

When a total R-value of 0.7 was reported for a major flow basin in an I/I study in the City of Columbus, it raised some eyebrows. A total R value of 0.70 meant that 70% of the rain water falling on the basin was making its way into the sewer system. Most shockingly, the sewer had only a very small section of combined sewer; it was almost entirely a separate sanitary sewer! When these extremely...

A chlorine system conversion project at the 91st Avenue Wastewater Treatment Plant was initiated to convert the bulk chlorine system which consisted of four 20-ton permanent storage tanks and two 17-ton mobile truck trailer mounted system to a multiple one-ton cylinder system. The project also included the replacement of plastic pipe used for the conveyance of both chlorine gas (vacuum) and...

Wastewater operators must have a clear understanding of pathogen inactivation across various treatment steps in order to ensure the production of high-quality potable reuse. The author provides an overview of pathogen log reductions made possible through the entire treatment train.

Dropping sewage from near surface collection systems into deep tunnels involves a number of challenges, including the odor control, air entrainment, solids management, energy dissipation, surge control, and access for personnel and equipment. The use of drop structures to handle large flows will become more prevalent over the next several years due to the large number of Combined Sewer Overflow...

Integrated design strategies in closed loop recirculating aquatic systems (RAS) enables unit operation refinement and process consolidation. With federally mandated increases in the levels of required waste water treatment, continued improvements in their economic competitiveness has resulted in closed loop systems receiving increased application in a wide variety of aquatic industries. The...