Master’s thesis proposal 2017 – Opportunities for increased nutrient recovery at centralised wastewater treatment plants through urine separation
Urine separation increases the fraction of organics in the municipal wastewater in relation to the nitrogen and phosphorus, since most of the nutrients origin from the urine and the organics origin from the feces and greywater. This open doors for more efficient nutrient recovery at the wastewater treatment plants (WWTPs) since assimilation and biological phosphorus removal redirects more of the nutrients into the sludge streams, which are more concentrated than the mainstream wastewater.
The City of Malmö, VA SYD and Sweden Water Research are working on urine separation as a solution to increase nutrient recovery from municipal wastewater.
The aim of this Master’s thesis project is to investigate the potential of increased nutrient recovery at the centralised WWTP when gradually increasing the degree of urine separation in the catchment area. The conceptual WWTP, which has no requirements for enhanced nitrogen removal, includes struvite precipitation (phosphorus recovery) and ammonia stripping (nitrogen recovery).
The conceptual WWTP should be modelled in the DHI software WEST®. The struvite precipitation and ammonia stripping parts will not be modelled WEST, but calculated in a simplified manner. A literature review of different struvite precipitation and ammonia stripping methods is included to determine the best set-ups for these processes. Also, the energy and chemical usage, as well as biogas production, should be calculated and compared to the conceptual WWTP without nutrient recovery.
Figure 1. The conceptual WWTP with urine separation in new urban areas, or in old urban areas where the piping systems in the houses are renovated.