February 2007, Vol. 19, No.2

Ditch the Phosphorus

An oxidation ditch system proves to be the most cost-effective phosphorus removal option for a Michigan plant

ditchthephosphorus.jpg Michael B. Curley

When staff at the wastewater treatment plant in Commerce Township, Mich., began upgrading the oxidation ditch facility, they had three major considerations: increasing installed capacity to 40,100 m3/d (10.6 mgd), on average, meeting an effluent phosphorus limit of 0.1 mg/L, and keeping costs manageable. 

The plant’s current effluent phosphorus limit is 0.5 mg/L (monthly average), but the Michigan Department of Environmental Quality has stated that the new phosphorus limit for the expanded plant will be 0.1 to 0.2 mg/L (monthly average). The new plant also must handle an average daily flow of 32,200 m3/d (8.5 mgd) when one of its largest process units is out of service and be able to treat an influent containing 292 mg/L of biochemical oxygen demand (BOD), 385 mg/L of suspended solids, 7.2 mg/L of phosphorus, 21.4 mg/L of ammonia–nitrogen, and 35 mg/L of total Kjeldahl nitrogen. Read full article



Work Force 2020

Two public utilities use skill-based training and certification programs to improve productivity and prepare for the future

scumbusters.jpg Stephen Hoffman and Stephen Kellogg

More than ever before, public utilities will need employees with greater skills to accommodate the demands of regulatory compliance, safety and reliability, optimization, community expectations, and loss of work force due to retirements.

Employees demand fair and equitable treatment, training resources, recognition for demonstrating increased skills, and opportunities for career advancement and to learn new skills that make them more valuable, employable, and mobile. At the same time, there is high demand for skilled workers in private-sector utilities and other industries.

How can a public utility address these challenges? It is possible to achieve a balance between the human side of a utility and its operational needs.
Read full article   Training resources



Be True to Your Grit

This new system is designed to manage grit under both wet and dry weather conditions

betruetoyourgrip.jpg Vince Maillard, Thor Young, Walt Bailey, and Tony Ramos

Storm-related grit doesn’t have to be an intractable problem. The District of Columbia Water and Sewer Authority has designed a grit-removal system that can handle a fifteenfold increase in grit without a hiccup. The authority’s Blue Plains Advanced Wastewater Treatment Plant has a headworks that can treat an average daily design flow of 1.4 million m3/d (370 mgd) and a design peak flow of more than 4.1 million m3/d (1076 mgd). The preliminary treatment facilities include influent pumping, fine screening, and grit removal. The grit-removal system includes 16 aerated grit chambers — four in Grit Chamber Building No. 1 and 12 in Grit Chamber Building No. 2. Grit chamber effluent is sent to the primary clarifiers. Read full article



Operations Forum Features

Less Power, Great Performance

System modifications shrink a Georgia membrane boireactor's power demand

lesspower.jpg Nicholas B. Cooper, John W. Marshall, Kevin Hunt, and John G. Reidy

Membrane bioreactors are compact and provide high-clarity effluent without secondary clarifiers or filters, but as power costs continue to rise, their high energy use makes them difficult to justify on a life-cycle basis. A Georgia treatment plant dealt with this challenge by modifying both the design and operations of its MBR facility to be more enrgy efficient. Read full article



The Savings Are in the Bag

Dewatering solids in porous geotextile bags

thesavingsareinthebag.jpg Arnold L. Greenleaf

When the Putnam Road Wastewater Treatment Facility (Newport, N.H.) began experiencing odor problems from the ever-increasing amount of solids exposed at the water line of its primary lagoon’s outside edge, it afforded the staff an opportunity to develop an inexpensive approach to removing and dewatering the solids. Solids were pumped from the primary lagoon, injected with polyaluminum chloride (PAC) to promote flocculation, and added to porous bags made of geotextile material.

After experimenting with variations on this approach, the staff are satisfied that this method can be used to remove and dewater solids from the lagoons for significantly less expense than draining and dredging. Read full article



Inspired Incineration

Targeted improvements, operator training,vastly improve incinerator performance

inspiredincineration.jpg Shaun O’Kelley, Robert Williamson, and F. Michael Lewis

The 105-mgd (400,000-m3/d) Blue River Wastewater Treatment Plant (WWTP) in Kansas City, Mo., uses multiple-hearth furnace (MHF) technology to incinerate primary solids. After experiencing numerous severe problems with its furnaces, staff at the facility worked with a consultant to revamp how the furnaces are maintained and operated and to make critical repairs. Despite severe budgetary limitations, furnace performance has improved significantly, thanks in large part to staff’s ability to maintain a consistent level of operation across all shifts. Read full article



Maximizing Methane

Testing a new method for optimizing the use of digester gas to generate power

maximizingmethanejpg.jpg Testing a new method for optimizing the use of digester gas to generate power

As part of an effort to retrofit an existing wastewater treatment plant (WWTP) with anaerobic digesters, the Columbus (Ga.) Water Works is developing a new process, known as Columbus Biosolids Flow-Through Thermophilic Treatment (CBFT3), to reduce pathogens and produce Class A biosolids.

The project will be demonstrated at the 67-mgd (253,600-m3/d) South Columbus Water Resource Facility (WRF), which currently treats approximately 35 mgd (132,500 m3/d) of raw sewage. As an added enhancement to the digestion operation, this effort, formally known as the CBFT3 Advanced Demonstration Project, also will attempt to optimize the use of the produced digester gas for generating combined heat and power, also known as cogeneration. Read full article