Chemical Pretreatments to Enrich the Acidogenic Phase in a System Coupled Packed Bed Reactor with a UASB Reactor Using Peels and Rotten Onion Waste

Biohydrogen production by Thermotoga maritima from a simplified medium exclusively composed of onion and natural seawater

“…The carbon to nitrogen ratio (C/N) of the onion was 15.3 [29]; this ratio was considered appropriate for prototroph anaerobic bacteria and therefore no additional nutrients were necessary [9,30].…”

Up-Flow Anaerobic Sludge Blanket (UASB) Technology for Energy Recovery: A Review on State-of-the-Art and Recent Technological Advances

“…Temperature pre-treatment and temperature-phased advanced AD were lately studied to facilitate veterinary antibiotic degradation [ 121 ], that is characterized by a significant refractory fraction. In another work, chemical pre-treatment of onion waste was proposed in a packed bed reactor coupled with a UASB reactor to reduce VFA accumulation and improve biogas yield [ 122 ]. Sulfuric acid pre-treatment, in particular, allowed to decrease the required start-up time, with methane yield up to 0.41 m 3 CH 4 /kg VS removed [ 122 ].…”

“…In another work, chemical pre-treatment of onion waste was proposed in a packed bed reactor coupled with a UASB reactor to reduce VFA accumulation and improve biogas yield [ 122 ]. Sulfuric acid pre-treatment, in particular, allowed to decrease the required start-up time, with methane yield up to 0.41 m 3 CH 4 /kg VS removed [ 122 ]. Mechanical solid-liquid separation of organic fraction of municipal solid waste (OFMSW), instead, allows to obtain a highly-degradable liquid fraction, called press water or leachate, able to produce consistent methane yields in high-rate systems, such as UASB reactor [ 16 ].…”