Selecting for a high lipid accumulating microalgae culture by dual growth limitation in a continuous bioreactor

A dual-growth-limited continuous operated bioreactor (chemostat) was used to enhance lipid accumulation in an enrichment culture of microalgae. The light intensity and nitrogen concentration where both limiting factors resulting in high lipid accumulation in the mixed culture. Both conditions of light and nitrogen excess and deficiency were...

Recovery of microbial biomass and purification performance after scraping of full-scale slow sand filters

Slow sand filters (SSFs) are widely used in drinking water production to improve microbial safety and biological stability of water. Full-scale SSFs are maintained by scraping the biomass-rich top layers of sand. The period of downtime required for filter recovery after scraping is a major challenge due to limited knowledge of the re...

Meta-omics profiling of full-scale groundwater rapid sand filters explains stratification of iron, ammonium and manganese removals

Rapid sand filters (RSF) are an established and widely applied technology for groundwater treatment. Yet, the underlying interwoven biological and physical-chemical reactions controlling the sequential removal of iron, ammonia and manganese remain poorly understood. To resolve the contribution and interactions between the individual reactions...

Characterization and Economic Evaluation of Biochar for Ammonium Adsorption

The nitrogen crisis is one of the biggest problems in society. Therefore, a tremendous amount of research is going on to solve this problem. This thesis focuses on solving the problem of nitrogenous emissions by capturing ammonium emissions from agricultural farms. Biochars have been gaining much attention due to their desirable properties, such...

Short and long term continuous hydroxylamine feeding in a granular sludge partial nitritation reactor

Hydroxylamine is a nitrogen intermediate of ammonium oxidizing bacteria (AOB) that can transiently accumulate during nitrification. The impact of hydroxylamine on aerobic ammonium oxidations is still obscure. In the present study the short and long term impact of hydroxylamine on partial nitritation granular sludge was investigated. Dissolved...

Application of dynamic current density for increased concentration factors and reduced energy consumption for concentrating ammonium by electrodialysis

Ammonium (NH₄⁺) can be recovered from water for fertiliser production or even energy production purposes. Because NH₄⁺ recovery is more effective at increased concentrations, electrodialysis (ED) can be used to concentrate NH₄⁺ from side streams, such as sludge reject water,...

Optimizing electrodialysis processes for concentrating ammonium rich streams

Ammonia in aqueous environments leads to eutrophication and toxicity of the receiving water body (Metcalf & Eddy, 2003). In order to prevent environmental pollution, ammonia needs to be removed from residual water streams, before the water can be discharged to the aqueous environment (Song et al., 2012). Waste water treatment plants (WWTPs)...

Concentrating Ammonium

This thesis provided an overview of the achievable ammonium concentrations, and the energy used to achieve these concentrations, by ion exchange, electrodialysis and reverse osmosis. The need for this overview arose during research for the N2kWh project, where one step in the process focused on increasing the ammonium concentration of (anaerobic...