CBE697 Biorefineries

Assignment 2: 20-mark Question

Faris Hafiyyan (2011801274), Masila Noraini (2011695452), Shahrizi Razali (2012401476)

QUESTION

PO2, PO6, CO2, C3, C4

China is the main player in swine industry. With the large expansion of the industry, Chinese

farmers are having difficulties in disposing of so many swine carcasses resulting from inevitable

routine mortality of pigs. Annually, a typical farrow-to-finish farming system produces over 90

tons of dead pigs. The usually farmer opt for burial, incineration and anaerobic digestion as

disposal techniques. The properties of the swine carcasses material is tabulated in Table 1.

Table 1 Proximate Analysis of Swine Carcasses Material

Component Carcasses Material

Moisture 8.8 wt%

Volatile 65.9 %

Ash 0.002 wt%

Fixed carbon 25.3 wt%

Heating value 39.3 MJ/kg

a) Deduce the negatives impacts of using conventional disposal techniques to dispose of

the swine carcasses

(6 marks)

b) Based on the information provide as the above, suggest the most suitable disposal

techniques that can be used to dispose of the swine carcasses in a safely, practically,

and economically manner. Explain the principle of the conversion process you have

chosen and the pretreatment needed (if any), as well as state the end-product and its

prospective uses.

(14 marks)

ANSWER

a) Negatives impacts of using conventional disposal techniques to dispose of the swine

carcasses incudes;

Direct burial and landfill disposal can cause contamination the groundwater supply

particularly in areas with light soil and a high water table

Direct burial and landfill can also cause infectious agents to enter the food chain for both

human and animal

Anaerobic digestion by microorganism generates high concentration of hydrogen sulfide

and other dangerous component that can exceed human safety levels

These released gasses can jeopardize the human health and some components are

malodorous

Incineration requires high operational cost and contributes to the air pollution

Lead to environmental pollution

[1 point x 2 marks = 6 marks]

b) Most suitable disposal techniques that can be used to dispose of the swine carcasses in a

safely, practically, and economically manner;

From the above table analysis of swine carcasses materials, swine carcasses can be

converted to bio-oil by alkaline hydrothermal liquefaction.

Feed are typically with 5 -35 % solid.

Process condition and requirement:

o Medium-temperature (between 280 – 370 ⁰ C)

o High pressure (10 – 25 MPa)

o Residence time (5 – 30 min)

o Water can simultaneously act as reactant and catalyst.

At these temperatures and pressures, water becomes a highly reactive medium

promoting the breakdown and cleavage of chemical bonds, allowing for the reformation

of biological molecules

Water is also beneficial as a reaction medium since the newly formed bio-crude oil self-

separates after conversion.

The aqueous medium also eliminates the need dry the incoming feedstock, bypassing

resource and energy intensive pre-processing steps.

The thermal and mechanical energy input for hydrothermal processes are considerable,

however by applying energy recirculation such as preheating the substrate with the

reactor effluent stream, the energy consumption can be reduced significantly

The fuel properties of the bio-oil are better than those of fast pyrolysis oil, but a little bit

worse than those of diesel.

A yield of end products comprises of bio-oil and solid residue such as carbon, hydrogen,

nitrogen, sulphur, oxygen, ash.

The bio-oil could further be upgraded by catalytic cracking or hydrodeoxygenation for

production of liquid transport fuels.

Some valuable chemicals, such as hydroxymethylfurfural (HMF) and levulinic acid, were

found in the bio-oils. Extraction of the valuable chemicals from the bio-oil could

significantly boost the economic attractiveness of the bio-oil.

[Total mark = 14 marks]