Simultaneous Biological Nutrient Removal: A State‐of‐the‐Art Review

Abstract

Simultaneous biological nutrient removal (SBNR) is the occurrence of biological nutrient removal (BNR) in systems that do not possess defined anaerobic and/or anoxic zones. A review of the relevant literature demonstrates that two mechanisms are primarily responsible for SBNR: (1) the bioreactor macro-environment and (2) the floc microenvironment. Complex hydraulic flow patterns exist in full-scale bioreactors that can result in the cycling of mixed liquor through the different environments needed for BNR. Diffusion resistance further allows oxygen-sufficient and oxygen-deficient zones to develop in activated sludge flocs if the external dissolved oxygen concentration is properly controlled. The diffusion of substrates between these zones allows BNR to occur. Long-term acclimation to the unique environmental conditions occurring in these systems results in the selection of microorganisms well adapted to the low dissolved oxygen concentrations occurring in them. The experience base for the design and operation of SBNR systems is expanding, thereby allowing their more widespread application, especially coupled with conventional mathematical modeling approaches. Computational fluid dynamics is an evolving tool to assist with the design and optimization of SBNR.

Energy positive domestic wastewater treatment: the roles of anaerobic and phototrophic technologies

“…31 However, anaerobic technologies have been demonstrated at psychrophilic temperatures 31,46,47 and have the potential to be applied more broadly for low-strength wastewater treatment. 25 Anaerobic wastewater treatment processes can generally be categorized as suspended growth, sludge blanket, attached growth, membrane-based, or microbial electrochemical systems. 32,48 The rst step of COD degradation in anaerobic treatment systems is the fermentation of complex organic matter into long chain volatile fatty acids, carbon dioxide, and hydrogen by acidogenic microorganisms.…”

“…Given that upgrades to U.S. infrastructure are expected to cost roughly $300 billion over the next 20 years, 6 the industry has an unprecedented opportunity to reenvision wastewater streams as resource-rich sanitation media. In particular, treatment strategies enabling nutrient recovery as well as energy recovery and generation should be advanced, enabling resource positive sanitationthe management of wastewater as a renewable resource for nutrient recovery and net energy production [24][25][26] that can have a net benet for the environment 27 to gain traction at a broad scale.…”

Application of dissolved oxygen (DO) level control for polyhydroxyalkanoate (PHA) accumulation with concurrent nitrification in surplus municipal activated sludge

“…In Batch tests 1-2, without organic carbon supply, nitrite and nitrate were both produced with low rates ( Figure 1d) at the low DO levels. Nitrate and VFAs diffusing into the flocs should, in principle, become consumed by anoxic respiration if DO levels within the floc become limiting [27,28]. In Batch L, TN concentrations decreased at the rate of 2.67±0.67 mgN/gCOD/h.…”

Alternative device for ANAMMOX/denitrification rate assessment using manometric method

“…Necessity of only partial oxidation of ammonium in this processes reduces net oxygen required for nitrogen removal to 1.71 mg O 2 /mg NH 4 + -N converted into gas if influent biodegradable organic matter is used to denitrify residual NO x -N [11]. Autotrophic metabolism of Anammox bacteria keeps this reaction independent from organic matter availability, as the inorganic carbon is used for biomass yield.…”