Hydrogen Production from Cassava Wastewater in Anaerobic Sequencing Batch Reactor: Effect of Cycle Time and COD:N Ratio

  • Ms Suchawadee Chatsiriwatana, The Petroleum and Petrochemical College, Chulalongkorn University, Thailand
  • A/Prof Thammanoon Sreethawong, The Petroleum and Petrochemical College, Chulalongkorn University, Thailand
  • A/Prof Sumaeth Chavadej, The Petroleum and Petrochemical College, Chulalongkorn University, Thailand
  • Assoc Prof Pramoch Rangsunvigit, The Petroleum and Petrochemical College, Chulalongkorn University, Thailand

    • Hydrogen is an environmentally friendly and feasible alternative to fossil fuel since it can reduce the emission of greenhouse gases into the atmosphere. Biological hydrogen production is of great interest because it can be produced from waste and wastewaters under ambient temperatures and pressures. Hydrogen production from cassava wastewater (CW) by dark fermentation process in anaerobic sequencing batch reactor (ASBR) using mixed culture was investigated. The seed sludge taken from an anaerobic lagoon treating CW was boiled for 15 minutes before being fed into the ASBR. The ASBR systems were operated at different chemical oxygen demand (COD) loading rates ranging from 10 to 25 kg/m3d with 5 kg/m3d increments at 4 cycles/d and 15 to 37.5 kg/m3d with 7.5 kg/m3d increments at 6 cycles/d under a mesophilic temperature of 37°C and a controlled pH of 5.5. The results showed that a COD loading rate of 30 kg/m3d at 6 cycles/d provided the maximum hydrogen production. A maximum specific hydrogen production rate (SHPR) of 388 ml H2/g VSS d (3800 ml H2/L d) and a hydrogen yield of 186 ml H2/g COD removed were obtained. The effect of nutrient supplementation was also studied by varying the COD:N ratio under a COD loading rate of 30 kg/m3d, 6 cycles/d, 37°C, and pH 5.5. The COD:N ratio of 100:2.2 provided a maximum SHPR of 524 ml H2/g VSS d (5680 ml H2/L d) and a hydrogen yield of 438 ml H2/g COD removed.