Joshua P. Boltz*, Steven J. Goodwin, Dana Rippon, Glen T. Daigger

¹ CH2M HILL, Inc. 4350 W. Cypress Street No. 600 Tampa, Florida 33607-4155.
*To whom correspondence should be addressed.

Abstract

Trickling filters (TFs) are an ideal habitat for a diverse microbial community enriched with animals, or fauna. Fauna may have a beneficial impact on carbon-oxidizing TF performance when in proper balance, but an infestation can be also detrimental in several ways. State-of-the-art TF-process designs must incorporate mechanisms to manage macro fauna. Snail infestation is a common TF operational issue that can degrade effluent quality, adversely impact biosolids handling infrastructure, and be detrimental to costly process mechanical equipment. The most significant detrimental performance impacts include (1) nitrifying biofilm grazing, (2) process mechanical equipment damage due to snail shells, (3) excess biochemical oxygen demand exerted by snail bodies, and (4) increased suspended solids measurements owing to snail shells and bodies. Little information exists in the environmental engineering literature detailing the production rate of higher life-form predators, such as snails, in the TF process and a corresponding lack of information on the effectiveness of snail control techniques. Only case specific studies related to substrate transformation reaction rates or fauna mass weight measurement methods have been used to quantify macro fauna production. This review (1) describes macro fauna that are commonly found in TFs treating municipal wastewater, (2) surveys state-of-the-art snail removal technologies and their reported effectiveness, (3) identifies protocol for implementing various snail removal technologies, and (4) presents means for creating a database that can be used to establish snail production and removal in TF-based wastewater treatment plants.

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John Fortin¹*, Paul Pitt¹, Patrick O’Connor², Frank Giardina², Joseph Husband³, Carl Koch⁴

¹Hazen and Sawyer,
²New York City DEP, New York City DEP,
³Malcolm Pirnie,
⁴Greeley and Hansen
*To whom correspondence should be addressed.

Abstract

In 2004, the Newtown Creek Wastewater Treatment Plant (WWTP), designed for 13.6 m3/sec average daily flow (ADF) was operating under an interim permit with new secondary treatment permit limits scheduled to go into effect in January 2008. The facility is currently undergoing a plant-wide upgrade that includes increasing the biological treatment facilities by 50% (from two to three treatment batteries) and changing the process from High Rate Modified Conventional Activated Sludge operation (SRT <0.5 days) to Low Solids Retention Time (SRT 1.8 – 2.2 days) Step Feed Activated Sludge operation. By January 2008, all three batteries were to be operational but only half the secondary system would be fully upgraded to the step feed process (Scheduled for completion in 2013). With no primary treatment facilities and the requirement to treat all influent flow  to a minimum of 27.2 m3/sec during rain events in this interim period, stable operation of the existing facility, particularly during rain events, was expected to be a challenge.

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K. Linares*, M. Haley¹, E. Grandstaff¹, H. Walker¹, E. Bailey², W. M’Coy²

*HDR Engineering, Inc., 5700 Lake Wright Drive, Suite 300 Norfolk, VA  23502.
¹City of Hopewell.
²HDR Engineering, Inc.
*To whom correspondence should be addressed.

Abstract

On approximately December 26, 2005, a publicly owned industrial treatment works (POITW) with high industrial loading treating approximately 27 million gallons per day experienced a treatment upset that significantly affected biological treatment performance through early January 2006.  This paper addresses some of the major challenges associated with treatment plant upset events, including identifying the onset of the upset condition and determining the cause and source of the upset.  Although the cause for the December 2005 plant performance upset could not be determined, the method of analysis outlined here can be applied at any facility investigating a treatment upset event.  This paper presents recommendations for additional monitoring to assist with identifying the onset of potential future upset conditions and sources.

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Stephen R. May¹, Michael Roys¹, W. James Gellner², Khamis A. Al-Omari²*

¹Lenawee County Drain Commissioner
² Hazen and Sawyer, P.C.
*To whom correspondence should be addressed.

Abstract

The objective of this paper is two-fold: 1) present the innovative concepts that were evaluated for treating septage using aerobic co-digestion of thickened waste activated sludge (WAS) and domestic septage, routing only the digesters decant to the plant headworks; and 2) discuss results of the full-scale pilot program for this co-digestion process, which was conducted at the 1.2- million gallons per day (mgd) Rollin-Woodstock Wastewater Treatment Plant (WWTP) in Lenawee County, Michigan between October 2006 and January 2007.  The full-scale pilot program used the two existing aerobic digesters at the plant to accept, screen, and co-digest domestic septage and WAS.

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Woodie Mark Muirhead*, Ron Appleton
¹Brown and Caldwell. Ali'i Place, Suite 2400, 1099 Alakea Street, Honolulu, Hawaii  96813.
*To whom correspondence should be directed.

Abstract

Nitrite-nitrogen seldom exceeds 1.0 milligram per liter (mg/L) in a properly controlled nitrification process.  As soon as ammonia is oxidized to nitrite by ammonia oxidizing bacteria (AOB), the nitrite is oxidized to nitrate by nitrite oxidizing bacteria (NOB).  Under certain environmental conditions, such as a poorly established or inhibited NOB population, the nitrite concentration will increase.  High nitrite concentrations can interfere with disinfection and cause violations of effluent bacteria limits, result potentially in whole effluent toxicity (WET) failures, and cause effluent pH violations.  An abnormal increase in secondary effluent nitrite is referred commonly as “nitrite lock”.  It is discussed frequently in the Water Environment Federations’ Technical Discussion Forum and is not understood fully.  This paper will explain nitrite lock, present case studies from four treatment plants, and outline operational strategies for preventing and controlling nitrite lock.

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J. Pawloski¹*, J. Peeters², B. Ginzburg², J. Winn³

¹GE Water & Process Technologies. ZENON Membrane Solutions, Oakville, Ontario, CA.
²GE Water & Process Technologies, ZENON Membrane Solutions, Ontario, CA.
³City of Pooler, Georgia, US.
*To whom correspondence should be addressed.

Abstract

A new membrane aeration energy reduction strategy for the membrane bioreactor (MBR) process was demonstrated at the Pooler wastewater treatment plant in Georgia.  Using the existing aeration equipment at the facility and making minor changes to the program logic controller (PLC) code, the new aeration strategy was implemented on two of the four membrane trains at the plant.  Six months of operation demonstrated that the new strategy results in membrane performance equal to that of the previous aeration method with a 50% decrease in the energy consumption due to membrane aeration under average daily flow conditions.  This new economical aeration method or “eco-aeration” was implemented on the entire plant in early 2006 at the request of the City of Pooler.  Based on local electricity costs of $0.055/kWh the new aeration method energy reduction resulted in savings in 2006 of $22.50 per million gallons treated.  This equated to a 5% reduction in the total monthly energy bill for the treatment plant.  The results of the trial are presented here.

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Patricia Tam, Henryk Melcer, L. Emil Voges, Bill McCarthy

¹Brown and Caldwell.
*To whom correspondence should be addressed.

Abstract

The City of Richland Wastewater Treatment Facility digesters have experienced Nocardia-induced digester foaming problems from the time they went into operation in 1985.  Because of the persistent foam, most or all of the thickened waste activated sludge (TWAS) was often not sent to the digesters but directly to the belt filter press to be dewatered separately from the digested sludge.  It was observed that Nocardia foam was generated in the two complete-mix aeration basins.  During a plant capacity assessment investigation, it was determined that one of the alternatives developed to increase the secondary system capacity coincided with one of the potential solutions previously identified to address digester foaming.  One of the aeration basins was converted to plug flow operation with an anoxic selector and the existing turbine sparger aerators were replaced by panel-type fine pore diffusers.  The upgrade included a classifying selector to provide physical foam removal from the aeration basin.  The upgraded system has been in operation for over a year, and the plant has thus far reaped several benefits from the upgrade, including the ability to operate one aeration basin with adequate aeration, limited digester foaming, significant energy cost reduction, the ability to send all of the TWAS to the digesters, and consequently lower biosolids production rate and cost for disposal.

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