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Cox, Alison E

University of British Columbia

Hydrothermal Liquefaction (HTL) is a thermo-chemical method of processing wastewater solids that could be preferential over anaerobic digestion (AD) because it produces no biosolids. Instead, the effluent can be separated into biocrude which can be refined into fuel, hydrochar that can be used for adsorption applications and HTL aqueous, the only waste stream of this process. Unfortunately, HTL aqueous is high in ammonia, phenolics and nitrogen heterocyclic compounds that can inhibit AD if it is used for disposal. Ammonia stripping was tested for pretreatment of HTL aqueous and recovering ammonia. Seven stripping reactor conditions were run, and the best results were seen at 85°C, a pH of 9.3 and 500 mL/min air flow rate. This case achieved ammonia removal of 99.5 ± 0.1% and total phenolic compounds removal of 32 ± 1% in 4 hours. The ammonia stripping was coupled with acid adsorption to produce an ammonium sulphate salt with value as fertilizer. The ideal ammonia stripping conditions produced a salt with a purity of 98.0 ± 0.05% and represented an ammonia recovery of 73.9 ± 0.04%. Semi-continuous flow bench-scale thermophilic anaerobic co-digestion of HTL aqueous with municipal sludge found that 12% of influent chemical oxygen demand (COD) can come from HTL aqueous without inhibition if pretreated with ammonia stripping, while the digester fed 13% of COD from non-pretreated HTL aqueous showed inhibition. Under mesophilic conditions, semi-continuous flow anaerobic co-digestion was successful for digesters fed with either 24% non-pretreated HTL aqueous or 22% pretreated HTL aqueous.

Text

2024-05-27

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88379

Civil Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/