Stripping and scrubbing of ammonium using common fractionating columns to prove ammonium inhibition during anaerobic digestion

Abstract

Anaerobic digestion to produce biogas is generally considered as one of the most sustainable technologies for the production of renewable energy. During this microbial process, organically bound nitrogen is released as ammonium that ends up in the digestate and finally may inhibit the process. In this study, it is investigated if ammonium can be removed and recovered out of the liquid fraction of a thermophilic digestate from a potato processor. This is achieved at laboratory scale through an easy and self-designed stripping and scrubbing process using Vigreux and Dufton columns, which are commonly used laboratory fractionating columns. The stripping is performed at pH 8.5 and at 323.15 K (50 °C), which results in the volatilization of the ammonium present in ammonia. Subsequently, the stripping gas charged with ammonia is put into contact with a sulphuric acid solution, resulting in (NH 4 ) 2 SO 4 , which can be used as an N-S fertilizer. In addition, the digestion experiments have demonstrated that the biogas yield is 36% higher after removal of the ammonium from the digestate compared to the untreated digestate.

Feedstock-Dependent Phosphate Recovery in a Pilot-Scale Hydrothermal Liquefaction Bio-Crude Production

“…Further research should consider how to approach the ammonium-rich post-precipitation liquid phase. Possible strategies include stripping ammonia and recovering it in the form of the fertilizer ammonium sulfate [89] or using activated carbon as a sorbent for ammonium separation. In such a case, the struvite crystallization could be beneficial as a pre-treatment technique.…”

Techno-economic assessment at full scale of a biogas refinery plant receiving nitrogen rich feedstock and producing renewable energy and biobased fertilisers

“…Effective dilution of chicken manure can be achieved by adjusting the C:N ratio with suitable feedstock or by recirculating N depleted digestate. Ghyselbrecht et al (2018) investigated the biogas production of pretreated digestate via NH 3 stripping as compared to untreated digestate. Results indicated that after eight days, biogas yields of stripped digestate was 36% higher, which was allocated to the lower NH 3 concentration in the digester.…”

Advances in Circular Bioeconomy Technologies: From Agricultural Wastewater to Value-Added Resources

“…Furthermore, the struvite precipitation can be combined with a pre-concentration process using membrane separation; for instance, the recovery of nitrogen using membrane-precipitation processes can be as high as 99-100% with energy consumption of 10 kWh/m 3 [90]. In addition to membrane separation, other techniques can be combined with a subsequent struvite precipitation for nutrient recovery, such as air stripping of ammonia from anaerobic digestion [85,91] and ion-exchange adsorption [92].…”