Screen versus cyclone for improved capacity and robustness for sidestream and mainstream deammonification

Abstract

Combining physical and metabolic selection allowed for determination of ideal operational conditions and capacity gain in full-scale deammonification systems.

Evaluation of a Full-Scale Suspended Sludge Deammonification Technology Coupled with an Hydrocyclone to Treat Thermal Hydrolysis Dewatering Liquors

“…To evaluate the hydrocyclone for its ability to retain the slow-growing AMX a mass balance and microbiome analysis were completed (Figure 1B). The biomass retention of AMX, AOB, and NOB (i.e., ηorganism) was calculated in Equation ( 1) [18], where r describes the volumetric activity rate in underflow and overflow as kg N m −3 d −1 . In order to evaluate the sludge/biomass separation in the hydrocyclone, the periods were examined for similar NLR, according to the statistical analysis described below.…”

“…Biomass separation strategies such as hydrocyclones or screens allow for process intensification and higher NLR of 0.5-1.0 kg N m −3 d −1 [17]. Anaerobic ammonia-oxidizing bacteria retention can be achieved by various separation strategies that rely on the density difference of bacterial flocs [18]. It is known that AMX aggregate in dense granules of 100-300 µm while AOB and NOB tend to form flocs >100 µm with lower density [19].…”

“…Only a handful of peer-reviewed studies discuss these processes in detail, their sludge separation ability and impact on deammonification efficiency, while their depiction and claims are taken for granted. The benefits of the biomass separation processes in the deammonification processes have been described as 75-95% biomass AMX retention [17,20,21], increased activity [20], overall resulting in enhanced nitrogen removal efficiency (NRE) up to 90% [18,20]. In a modelling study, Van Winckel (2019) [18] evaluated the impact of different SRTs on the biomass type (AOB, AMX, and NOB) and identified that greater AMX retention of 88-91% could lead to the enhanced nitrogen removal rate of 1.04-1.16 kg N m −3 d −1 .…”

Ammonia removal from mixed dewatering liquors by three different deammonification technologies

“…Which could indicate that the S-SBR was limited by AMX rather than AOB. Past studies discussed that the anammox conversion could be enhanced when using an external selector such as a sieve or a hydrocyclone 42 . In the MEDIA, it was observed that the biofilm on the plastic media was coloured blackish, similar to the G-SBR, indicating heterotrophic growth.…”

“…With the AMX biomass in small flocs in suspension, biomass retention in the biological reactor was only achieved by gravity. It has been suggested that an external selector could enhance the removal efficiency of suspended sludge deammonification technologies by either using a hydrocyclone or a sieve 42 . Overall, it was found that an NRR of 0.30 kgN m -3 d -1 could be maintained at an average temperature of 17°C, implying that the deammonification technologies are robust enough to cope with sudden heat-loss or seasonal temperature fluctuations.…”