The efficiency of wastewater treatment practices can be significantly improved through the introduction of new microbial treatment technologies. In order to meet increasing stringent discharge standards, new applications and control strategies for the sustainable removal of ammonium from wastewater have to be implemented. Partial nitrification to nitrite was reported to be technically feasible and economically favorable, especially when the wastewater with high ammonium concentrations or low C/N ratios was treated. For successful implementation of the technology, the critical point is how to maintain the partial nitrification of ammonium to nitrite. Nitritation can be obtained by selectively inhibiting the nitrite oxidizing bacteria through appropriate regulation of the system's DO concentration, microbial SRT, pH, temperature, substrate load, operational and aeration pattern, inhibitor and so on. This review addresses the microbiology, its consequences for application, the current status regarding application, and its future developments.

Biological nitrogen removal with nitrification and denitrification via nitrite pathway

Over the past few years, new technologies for nitrogen removal have been developed mainly because of the increasing financial costs of the traditional wastewater treatment technologies. Newly discovered pathways, like the anaerobic oxidation of ammonium (ANAMMOX), and uses for nitrogen removal technologies are under discussion. Processes and technologies such as: Partial nitrification; Single reactor systems for High Ammonium Removal Over Nitrite (SHARON); Anammox; Aerobic/anoxic deammonification; Oxygen Limited Autotrophic Nitrification-Denitrification (OLAND); Completely Autotrophic Nitrogen Removal Over Nitrite (CANON); wetland based systems, all have a high potential for nitrogen removal. However, the pathways of nitrogen transformation processes are very complex. An understanding of how various environmental factors affect these processes and a sound knowledge of existing, worldwide experience pertaining to these novel technologies are the key if the nitrogen removal rates are to be improved and success is to be realized in full-scale applications. This review describes the present knowledge of the new treatment technologies for wastewater with high nitrogen loads. Special emphasis is given to the influence of environmental factors and the reactor configuration on the nitrogen transformation process and microbial activity.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/elsc.200620170

New Aspects of Microbial Nitrogen Transformations in the Context of Wastewater Treatment – A Review

Influence of aeration and sludge retention time on ammonium oxidation to nitrite and nitrate.

Operation of a nitrite-type airlift reactor at low DO concentration.

Bauxite residue is a highly alkaline material generated from the production of alumina in which bauxite is dissolved in caustic soda. Approximately 4.4 billion tons of bauxite residues are either stockpiled or landfilled, creating environmental risks either from the generation of dust or migration of filtrates. High alkalinity is the critical factor restricting complete utilization of bauxite residues, whilst the application of alkaline regulation agents is costly and difficult to apply widely. For now, current industrial wastes, such as waste acid, ammonia nitrogen wastewater, waste gypsum and biomass, have become major problems restricting the development of the social economy. Regulation of bauxite residues alkalinity by industrial waste was proposed to achieve ‘waste control by waste’ with good economic and ecological benefits. This review will focus on the origin and transformation of alkalinity in bauxite residues using typical industrial waste. It will propose key research directions with an emphasis on alkaline regulation by industrial waste, whilst also providing a scientific reference point for their potential use as amendments to enhance soil formation and establish vegetation on bauxite residue disposal areas (BRDAs) following large-scale disposal.

J. Surmacz-Gorska

Papers

Nitrogen removal from wastewater with high ammonia nitrogen comcentration via shorter nitrification and denitrification