The Blue Plains Advanced Wastewater Treatment Plant (AWTP) uses a two-stage activated sludge system, including methanol-driven nitrification/denitrification (NDN) in the second-stage to meet stringent effluent limits, including a total nitrogen (TN) objective of 7.5 mgN/L. In the near
future, the plant will be undergoing construction of an advanced anaerobic digestion system with biosolids dewatering. It has been estimate that the dewatering centrate will increase the (TN) load by approximately 40% on the NDN plant. One of the most significant effects will be the substantial
increase in methanol chemical costs as the plant currently spends between $7-8 M annually on this chemical alone. This paper presents a review of alternative strategies to mitigate the impact of the centrate. Two alternative were short-listed for a more detailed review; (1) the SHARON
process, and (2) a new process configuration conceived by the authors which has tentatively been named the MAUREEN process. The detailed review included process modeling to determine the relative benefits of these alternatives, including reductions in methanol dosage and process aeration requirements.
The capital cost of installing the SHARON and MAUREEN processes were estimated to be $14.6M and $21.3M, respectively. However, total annual methanol and aeration savings were estimated to be $2.8M greater for MAUREEN compared to SHARON. The analysis indicates that both
the SHARON and MAUREEN processes should be considered viable alternatives to mitigate the impact of centrate at the Blue Plains AWTP.
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