biosolids

City of Raleigh

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NEUSE RIVER RESOURCE RECOVERY FACILITY

Bioenergy Recovery Project

BIOENERGY RECOVERY PROJECT

The City of Raleigh's

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Raleigh's

BIOGAS

The new NRRRF biosolids process will produce green energy, qualifying the City for a 0% interest loan for a savings of over $25M.

The biogas produced in anaerobic digestion will be converted to RNG and used for vehicle fuel – as many as 50 city buses!

INNOVATIVE TECHNOLOGIES

A high-quality, low-odor Class A biosolids material will be produced, enhancing reuse and minimizing impact to the environment.

BENEFITS

BIOSOLIDS

GREEN ENERGY

Four Key Benefits of Implementing THP and Anaerobic Digestion

FOG

CLICK OR TAP ON ICONS TO LEARN MORE

Biosolids Bonus

Fats, Oils and Grease (FOG) will be collected for co-digestion to boost biogas production in the digesters.

Implementing ultra-efficient sidestream treatment saves the City money and energy, with a payback period of less than 10 years.

RNG

The Bioenergy Recovery Project will produce enough fuel for 50 City buses or 3,000 passenger vehicles!

Biogas produced by anaerobic digestion will be cleaned and converted to Renewable Natural Gas (RNG). This green energy can be used for vehicle fuel, either in City buses or sold to a third party for revenue.

City Buses

3rd-Party Vendors

Biogas

Raleigh

Air and Water Flow

Plastic Media

Bioreactor

TREATMENT

Each reactor contains millions of discs.

The AnitaMOX Sidestream Deammonification uses special bacteria that grow on plastic media to remove nitrogen from recycle streams in an ultra-efficient way. By implementing sidestream treatment at Neuse River RRF, the City will save money and energy while protecting the river from pollutants.

Anaerobic Layer

Media

Plastic Media The plastic media provide maximum surface area to which bacteria attach, eventually filling most of the gaps and interior surfaces. Sidestream treatment can remove about 80% of ammonia and about 70% of the total nitrogen in the recycle stream.

Plastic Media Media float in the reactor. Their design allows water to flow in and around all biofilm surfaces.

SIDESTREAM

Bacteria form two layers that remove ammonia and nitrogen from the water.

Bacteria

Aerobic Layer

Plastic Media The polyethylene discs provide highly-effective surface areas on which the biofilm grows.

Overall, Thermal Hydrolysis + Anaerobic Digestion cuts the amount of Biosolids produced at plant by half.

The new biosolids produced at NRRRF will be all Class A and can be readily marketed and distributed for beneficial uses.

Reducing odor

Increasing dryness to reduce hauling costs

THERMAL HYDROLYSIS IMPROVES THE QUALITY OF THE FINAL BIOSOLIDS PRODUCT BY:

Enhancing digester performance to minimize residuals

Reducing pathogens and risk to the environment

THP

Cleaning

NET ENERGY PRODUCTION

Recycled Energy

$25 MILLION SAVINGS

BIOGAS

Compared to traditional bond financing.

ENERGY

The Bioenergy Recovery Project will allow the City to create energy in the form of methane gas rather than spend more energy for biosolids treatment.

GREEN

This conversion from an energy consuming to an energy producing process qualified the City for Clean Water State Revolving Fund Green Project Reserve Funding of a $50M loan at 0% interest rate.

Digester

Natural Gas Transmission Line

Revenue from RNG, and recycling gas to fuel boilers used for THP, results in a net energy production.

Editorial

Boiler

FOG Collection

Commercial Businesses

Receive revenue from FOG tipping fees.

Biogas Production

Reduce clogs in sewers and sewage spills.

Implementing Fats, Oils and Grease (FOG) collection at NRRRF will provide a triple benefit:

Digesters

Boost gas production in the anaerobic digesters.

The biogas will be cleaned and converted to renewable natural gas (RNG), and can be used in the City’s bus fleet.

The City of Raleigh is strategically implementing cutting edge technology at the Neuse River RRF to more sustainably manage the biosolids residuals of wastewater treatment.

The City is converting biosolids processing at NRRRF with Thermal Hydrolysis Pretreatment (THP) for enhanced anaerobic digestion.

Benefits of the Bioenergy Recovery Project include: __• Green energy production __• High quality, low odor Class A biosolids product

INTRODUCTION

Raw Sludge from Clarifier

PROCESS

Clarifier

THP creates more Biogas than conventional anaerobic digestion as well as high-quality Class A Biosolids.

THP

Steam

THP enhances anaerobic digestion by ripping apart cell walls and making the biosolids more digestable. The process works in a manner similar to a pressure cooker that uses steam to achieve high temperature and pressure.