Principles and potential of the anaerobic digestion of waste-activated sludge

http://www.bashanfoundation.org/gmaweb/pdfs/P-removal.pdf

Recent advances in removing phosphorus from wastewater and its future use as fertilizer (1997-2003).

Nitrous oxide (N2O) emissions from wastewater treatment plants vary substantially between plants, ranging from negligible to substantial (a few per cent of the total nitrogen load), probably because of different designs and operational conditions. In general, plants that achieve high levels of nitrogen removal emit less N2O, indicating that no compromise is required between high water quality and lower N2O emissions. N2O emissions primarily occur in aerated zones/compartments/periods owing to active stripping, and ammonia-oxidizing bacteria, rather than heterotrophic denitrifiers, are the main contributors. However, the detailed mechanisms remain to be fully elucidated, despite strong evidence suggesting that both nitrifier denitrification and the chemical breakdown of intermediates of hydroxylamine oxidation are probably involved. With increased understanding of the fundamental reactions responsible for N2O production in wastewater treatment systems and the conditions that stimulate their occurrence, reduction of N2O emissions from wastewater treatment systems through improved plant design and operation will be achieved in the near future.

https://royalsocietypublishing.org/doi/pdf/10.1098/rstb.2011.0317

Nitrous oxide emissions from wastewater treatment processes

Parameters affecting biological phosphate removal from wastewaters

The removal of ammonia from wastewater has become a worldwide emerging concern because ammonia is toxic to aquatic species and causes eutrophication in natural water environments (Tchobanoglous et al. 2003). Nitrogen compounds in wastewater can only be effectively removed by biological approaches (EPA 1993; Zhu et al. 2007a,b). Based on the microbial nitrogen cycle and the metabolism of inorganic nitrogen compounds (Fig. 1), many biological technologies and processes have been developed and implemented for nitrogen removal from wastewater, such as predenitrification (Anoxic/Oxic), modified Bardenpho, Bio-denitro, sequencing batch reactor (SBR), oxidation ditch (OD), step feeding, anaerobic/anoxic/ aerobic (A2/O), and University of Cape Town (UCT) processes (Wentzel et al. 1992; Ostgaard et al. 1997; Williams and Beresford 1998; Tchobanoglous et al. 2003; Pai et al. 2004). These processes have been widely employed in wastewater treatment plants for nitrification and denitrification (EPA 1993). However, with the effluent discharge standards having become more stringent (<10mg total nitrogen/L), conventional processes cannot meet the new requirements (Khin and Annachhatre 2004).

Ewa Lie

Papers

A comparison between ethanol and methanol as carbon sources for denitrification

Influence of dissolved oxygen and oxidation–reduction potential on the denitrification rate of activated sludge

Anoxic biological phosphorus removal in a full-scale UCT process

A method for determination of the readily fermentable organic fraction in municipal wastewater

Operational factors affecting enhanced biological phosphorus removal at the waste water treatment plant in Helsingborg, Sweden