Maximizing Beneficial Use of Influent and High Strength Waste Organic Carbon


  • Wendell Khunjar PhD

Effective organic carbon management is critical element of efforts at water resource recovery facilities (WRRFs) seeking to achieve electrically neutral or positive operating status, while also reducing ENR operating costs. Efforts to perform next generation nitrogen removal (NGN; e.g. nitritation/denitritation or deammonification pathways) typically require redirection of organic carbon from liquid to solids processes. The redirected carbon is used as a feedstock for anaerobic processes that yield methane, which can be beneficially recovered.

Presently, NGN efforts do not ascribe value to carbon within the context of promoting phosphorus removal and recovery. Further, little consideration is currently given to the ability to recover high value carbon products other than methane (e.g., volatile fatty acids or biopolymers). Given that phosphorus removal and recovery and high value carbon recovery can provide economic benefits at WRRFs, the question begs, “What is the most effective use of organic carbon at WRRFs?”

In this work, we will present a framework that can be used for properly evaluating the value of organic carbon at WRRFs within the context of:

1) Offsetting supplemental carbon for nitrogen removal – Since not all facilities will adopt NGN processes, it is necessary to understand how to utilize influent carbon to minimize costs associated with nitrogen removal.

2) Enhancing phosphorus removal and recovery – Boosting biological phosphorus removal can help offset metal salt addition costs and position a facility to recover struvite.

3) Attaining electrical energy independence – Biogas production can offset peak electrical costs.

4) Facilitating revenue generation at WRRFs – High value carbon products (e.g., volatile fatty acids, biopolymer) have higher revenue potential than methane.

We will present results that discusses the whole plant implications of managing carbon at a full scale WRRF. Capital and operating cost implications as well as product recovery potential analyses will be provided.

For more information, please contact the author at

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Horizons Fall 2017 (pdf)

Horizons showcases significant water, wastewater, reuse, and stormwater projects and innovations that help our clients to achieve their goals, and can help you achieve yours. Articles are written by top engineers and process group leaders, demonstrating and explaining the beneficial application of a variety of technologies and tools.

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