(61b) Fuel Gas Production from Grey Water Using a Hybrid Digestion-Biomass Gasification Energy System | AIChE

(61b) Fuel Gas Production from Grey Water Using a Hybrid Digestion-Biomass Gasification Energy System

The demand of the world economy for electrical and thermal energy in over 88% is covered from
nonrenewable energy,  mainly petroleum and  natural  gas, (Krzysztof & Magdalena, 2012). To address
the growing need for increased sustainability for, this create the need for the alternative energy
which will be cleaner and easier to handle and the world start pay attention towards the field.
This work focuses on three areas:
1.   Design a two stage digester using ASPEN,
2.   Construct and operate a pilot facility to test this hybrid concept, and
3.   Conduct a statistical analysis of the test data to identify the optimum operating conditions
for the hybrid system.
A hybrid digester-gasifier system to produce methane and chemicals from Grey Water (municipal waste
water) and from solid municipal waste (biomass) has been designed. The gasifier is designed and
built at Brigham Young University-Idaho. The unit is equipped with natural gas burner as combustion
zone to supply heat to the reactor. This work focuses on the digester portion of this hybrid energy
system.
Digestion consists of three steps including: hydrolysis, acidogenesis, and finally methanogenesis:
hydrolysis is considered the controlling rate-limiting reaction step. The digester includes a plug
flow reactor followed by continuous stirred tank reactor and is used to produce methane from Grey
water.
Designing the digester focused on evaluating several operating parameters including pH level,
temperature for both reactors, biomass content in waste water, and reactor residence time each of
which has significant impact on methane production.
This is a two-step method. First, develop the Aspen model and conduct the designed experiment to
identify key operating factors. Second, using these results develop a bench-scale reactor system
which can be used to conduct experiments to validate (refine) the Aspen model. Once validated, the
Aspen model can be used to scale the process up to pilot scale and eventually industrial scale.  
Economics and sustainability of the overall process can also be evaluated using
the Aspen based process model.