Implementing and Sustaining a Membrane Bioreactor

Discover the steps taken by this Texas facility to successfully integrate and maintain a brand-new membrane bioreactor (MBR) into its wastewater treatment process, ensuring continuous operation and high-quality effluent.

At a Glance:

The North Texas Municipal Water District (NTMWD) initiated a multi-phase improvement plan for the Rowlett Creek Regional Wastewater Treatment Plant (RCRWWTP) in 2017.
In the first phase, NTMWD installed a membrane bioreactor (MBR) to enhance reliability and peak flow capacity.
Faced with initial startup challenges, NTMWD collaborated with Hazen to develop a robust restart plan, addressing root causes and risks.
The successful restart included process performance validation, staff training on the new automated system, and ongoing operational support to ensure long-term functionality.

Increasing Capacity on a Constrained Site

Built in 1956, the RCRWWTP in Plano, TX, owned by NTMWD, is a 24 mgd plant undergoing updates. In 2017, NTMWD began a multi-phase plan to increase peak flow capacity to 120 mgd. The first phase installed an MBR, boosting two-hour peak flow from 60 mgd to 77.5 mgd, with future phases aiming for 95 mgd and eventually 120 mgd.

A Single Integrated System

Unlike traditional systems with large concrete clarifiers, the MBR uses hollow fiber microfiltration membranes for solid/liquid separation. This integrated system consolidates treatment into a single unit, reducing the footprint compared to conventional clarifiers.

At Rowlett Creek, MBR effluent undergoes UV disinfection and post-aeration before reaching the effluent junction. This process produces high-quality effluent suitable for reuse and discharge to Rowlett Creek.

Brandt Miller serves as a regional Wastewater Practice Lead for Hazen, with extensive experience in design, evaluation, and optimization of wastewater treatment facilities.

Evaluating Startup Challenges and Ensuring Ongoing Success

Staff faced challenges with initial startup of the MBR and enlisted Hazen to develop a restart plan through field analysis, process modeling, and capacity validation. Sampling identified alkalinity and pH issues as root causes.

Hazen coached plant operators on the new startup plan, monitored parameters, and mitigated risks. They provided on-site support during the week-long testing to confirm standards were met.

Sustained Support for Complex Operations

Since the restart, Hazen has continued supporting NTMWD with monthly calls to review data and troubleshoot issues as operators gain experience with the MBR system. This ongoing support reflects Hazen’s commitment to considering operational realities in their designs.

“We’ve been walking with them throughout this last year as they learn,”
Brandt Miller, PE, project lead.

West Rowlett Creek 2 — Rowlett Creek RWWTP's existing discharge outfall supplies fresh water for downstream aquatic life during dry weather.

Discharging to the Creek

Throughout the MBR installation and restart, the plant remained online, maintaining water quality to the creek.

“At the end of the day, especially here in North Texas, the effluent from wastewater treatment plants ends up back in our surface water streams and our reservoirs,” says Miller “If we are not treating wastewater to a specific quality that meets the environmental requirements, then we are also hurting ourselves and our drinking water supply here in Texas. It’s a fundamental requirement to return water to the environment at a higher quality than we pulled it out,” Miller adds.

Beyond the MBR

Installing new technology at a plant is a big task that requires everyone to learn new processes. The MBR at RCRWWTP is running smoothly as the multi-phase improvement plan progresses. With ongoing support for the operations staff and engineering teams, Hazen and NTMWD are set to handle the complexities of updating and maintaining the MBR well into the future.