Achieving low TN effluent by operating AvN control coupled with partial denitriflcation-anammox control

摘要

Achieving energy neutrality is an important driver for utilities to start investing in both carbon redirection and advanced digestion to enhance energy recovery, as well as in short-cut nitrogen removal technologies to minimize energy consumption. Recent work on carbon redirection using high-rate activated sludge systems has shown the potential to harvest about 60% of influent organics for recovery to energy, significantly increasing the chance of reaching energy neutrality (Rahman et al., 2016; Miller et al 2017, Jimenez et al 2015). However, as the latter high-rate activated sludge systems decrease the organics available for nutrient removal, a combination of C-redirection with short-cut nitrogen removal technologies seems a necessity. Based on the available research data on mainstream short-cut N removal technologies, it can be concluded that one of the most common requirement for achieving out-selection of nitrite oxidizing bacteria (NOB) is to maintain an ammonium residual concentration of 1-2 mg N/L. To comply with nutrient discharge limits in USA, additional polishing would be required. In this study we demonstrate a combination of short-cut nitrogen removal, controlled via AvN control, with a polishing step based on partial denitrification (NO_ _3~-→NO_2~-) and anammox, controlled by N03 based COD dosing, to achieve low TN effluent concentrations which are in compliance with Chesapeake Bay TMDLs.