Method and apparatus for nitrogen removal in wastewater

Abstract

A reactor and control method thereof for nitrogen removal in wastewater treatment achieves a measured control of maintaining high ammonia oxidizing bacteria (AOB) oxidation rates while achieving nitrite oxidizing bacteria (NOB) repression, using various control strategies, including: 1) ammonia and the use of ammonia setpoints, 2) operational DO and the proper use of DO setpoints, 3) bioaugmentation of a lighter flocculant AOB fraction, and 4) proper implementation of transient anoxia within a wide range of reactor configurations and operating conditions.

Description

[0001]This application claims the benefit of U.S. Provisional Application No. 61 / 700,717, filed Sep. 13, 2012. The entire disclosure of U.S. Provisional Application No. 61 / 700,717 is incorporated herein by reference.BACKGROUND[0002]The inhibition of nitrite oxidizing bacteria (NOB) is a precondition for the implementation of short-cut biological nitrogen removal (ScBNR) processes such as nitritation-denitritation (Ciudad et al., 2005; Gee and Kim, 2004; Ju et al., 2007; Yoo et al., 1999; Yu et al., 2000; Zeng et al., 2008), nitrite-shunt and partial nitritation-anammox (Fux et al., 2002; Hippen et al., 1997; van Dongen et al., 2001; Wett, 2006; Wen, 2007; Wett et al., 2010), and deammonification. Successful repression of nitrite oxidation by controlling NOB saves 25% oxygen and 40% organic carbon compared to conventional nitrification-denitrification (Turk and Mavinic, 1986; Abeling and Seyfried, 1992). In deammonification processes, the control of NOB results in added benefits in f...

AI Technical Summary

Benefits of technology

The invention allows for better control of high AOB oxidation rates while reducing NOB occurrence. This is achieved through various control strategies such as ammonia and its setpoints, operational DO and its setpoints, bioaugmentation of a lighter flocculant AOB fraction, and proper implementation of transient anoxia within a wide range of apparatus and operating conditions.

Problems solved by technology

However, knowledge of controlling FA inhibition to obtain stable nitritation is more limited since NOB adaptation has been reported (Turk and Mavinic, 1989; Wong-Chong and Loehr, 1978).

In spite of being effective, the role of elevated temperature to increase activity of AOB and for the control of NOB growth is not feasible in low strength mainstream processes operating under wide range of temperatures.

Consequently, NOB control in low strength wastewater remains intractable and requires careful manipulation of factors other than temperature or free ammonia.

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