Evaluation and Design of Odor Abatement Improvements

Lewisville, Texas

PECI was retained by the City of Lewisville to conduct emissions testing and dispersion modeling for prediction of off-site odor impact from odorous process units at the WWTP. The treatment processes found to cause the greatest off-site odor impact include the influent splitter boxes, fine screens and aerated grit basins.

PECI was also retained to provide design services for odor control improvements at the headworks processes. Foul air from the influent splitter boxes, fine screens and grit removal basins is combined and handled by a single biotrickling filter or bioscrubber.

The foul air flow to effectively capture odorous emissions from the grit removal system was reduced by converting the aerated grit basins to vortex grit removal basins. The vortex grit removal units are being constructed within the existing aerated grit basins, saving on inlet and outlet piping modifications.

Screenings from five existing drum screens were previously directly discharged into five large dumpsters. Screenings disposal was simplified with a dual washer/compactor system. Benefits include reducing the volume and weight of screenings by about 50- to 80-percent and a reduction of odors by removing organics from the screenings.

The project was completed in 2016 for the bid amount of $3.2 million.

Lewisville Dispersion Modeling Results

Odor Control Isopleths Showing Offsite Odor Impact

Evaluation and Design of Odor Abatement Improvements for New WWTP

Hutto, Texas

PECI assisted a larger team of consultants with design of a new, state of the art wastewater treatment facility to serve the City of Hutto. The plant is being built from the ground up and will be operated by the Brazos River Authority when complete.

PECI modeled odor dispersion from the plant’s major process units and assisted with selection of odor control improvements designed to keep detectable off-site odors to a minimum practical level. PECI personnel participated in a public meeting at the site and assisted in developing odor-related language for incorporation into an agreement with nearby landowners, enabling formal permit protests to be withdrawn.

PECI designed an organic media biofilter, ductwork, and a foul air collection system to serve the plant’s headworks structure and dewatering building.

The opinion of probable construction cost for odor control was $400,000. This project was bid in March 2015.

OU Isopleths shown on Aerial Map_Controlled

Odor Dispersion Model Isopleths

Biosolids Odor Evaluation

Fort Worth, Texas

PECI was retained by the City of Fort Worth to assist with an evaluation of the impacts from a number of processes and activities on odor generation potential from the biosolids produced by the Village Creek Water Reclamation Facility (VCWRF). The City desired to proactively address odors at remote beneficial use sites. The project targeted identifying management options within the stabilization, dewatering, storage and transportation process to enable the City and/or its biosolids handling contractor to minimize odor emissions at the beneficial use sites.

The evaluation used simplified test methodologies to assess the impact of certain key processes and factors on odor production potential within the dewatered product. The test methodologies were developed to provide guidance with respect to the management options most likely to practically reduce dewatered biosolids odors.

The proposed test protocol addressed the following parameters related to biosolids odor production, with specific tests related to each:

  • Impact of co-digestion
  • Impact of lime
  • Impact of stockpiling, holding and transport practices
  • Impact of polymer dosing practices
  • Impact of water plant residuals

A local belt filter press manufacturer assisted by dewatering the samples used to evaluate the impacts of co-digestion and polymer. After sampling the parameters identified in the initial test protocol, the impacts of varying the lime dose as well as stockpiling cake were also evaluated.

Odor Control System Replacement

Lucas, Texas

PECI assisted the North Texas Municipal Water District with replacement of two chemical scrubber systems using manu­factured bioscrubbers at the District’s “flagship” Wilson Creek Wastewater Treatment Plant. The new equipment will yielded a chemical cost savings resulting in a three to four year return on investment. PECI previously assisted with a major corrosion repair initia­tive for the plant’s four 110-foot primary clarifiers.

PECI developed an odor dispersion model illustrating intensity, frequency, and spatial extent of nuisance odors generated by the treatment facilities. Both existing con­ditions and anticipated future conditions with the new primary clarifier bioscrubbers were modeled.

PECI is presently assisting the District with addition of a third bioscrubber at this facility.

 

Odor Dispersion Model and Odor Abatement Improvements

Richardson, Texas

Perkins Engineering Consultants, Inc. was retained by the District to conduct dispersion modeling and to recommend and design specific odor abatement improvements for this plant in Richardson, Texas. Perkins Engineering Consultants, Inc. modeled several different dispersion and improvement scenarios. Design of odor control improvements included full covers on the Plant’s primary clarifier, cover and exhaust improvements to the Plant’s main left station, and addition of a bioscrubber for treatment of foul air. Construction was completed in 2014.

Odor Control Planning and Design

Wichita Falls, Texas

Perkins Engineering Consultants, Inc. was retained by the City of Wichita Falls to perform and odor source assessment and to develop an odor control master plan for the City’s 19.5 MGD River Road Wastewater Treatment Plant. PEC assisted with design of the first phase of odor abatement improvements, which includes primary clarifier weir covers, junction structure covers, corrosion repairs and a 7500 CFM foul air collection system. Construction was completed in fall of 2008.