MICROBIOLOGY, BIOCHEMICAL CHANGES AND BIOGAS PRODUCTION DURING BIODEGRADATION OF OIL PALM EMPTY FRUIT BUNCH

2900.00

MICROBIOLOGY, BIOCHEMICAL CHANGES AND BIOGAS PRODUCTION DURING BIODEGRADATION OF OIL PALM EMPTY FRUIT BUNCH

 

CHAPTER ONE

INTRODUCTION

Oil palm is a tropical plant that grows in warm climate at altitudes below 500 meters above sea level.  It  came  from  the  Gulf  of  Guinea  in  West  Africa,  which  explains  its scientific  name,  Elaeis  guineensis  Jacq.  and its  popular  name,  the  African  oil  palm.  In Nigeria, oil palm tree is widely grown and is a valuable economic crop that provides a source of employment and revenue to farmers.. It allows many small landholders to participate in the cash economy.  Oil palm is a major source of edible oil which is extracted from fruits (Lua and Gua, 1998). However, palm oil mills produce a large amount of solid wastes. The  remainder of  the oil palm consists of huge  amount  of  lignocellulosic materials  such  as  oil  palm  fronds, trunks, palm  kernel and  empty  fruit  bunches. The  residues  contain 7.0 million  tonnes  of  oil  palm trunks, 26.2 million  tonnes  of  oil  palm  fronds and 23% of Empty Fruit Bunch (EFB) per tonne of Fresh Fruit Bunch (FFB) processed in oil palm mill. Palm oil is a source of income and is also used as food. Palm kernel produces palm kernel oil and palm kernel shell when processed. The palm kernel oil is a source of income while the palm kernel shell can be used as a source of heat energy. The  leaves  are  used  for  the  production  of  brooms  and  for  the construction of local fence. The trunk can be used as fire wood and can be sewn into planks for use in roofing.

The Oil Palm EFB is a suitable raw material for recycling because it is produced in large quantities in localized areas. In the past, it was often used as fuel to generate steam at the mills (Ma, Cheah and Chow, 1993). The empty fruit bunch can also be used as local fertilizer.

The  ash  produced  from  empty  fruit bunches  is sprayed on crops  to prevent  insects from destroying  the crops,  it  is also used for washing of plates and pots. The ash, with a potassium content of about 30% was used as fertilizer.  The  filtrate obtained  from  the  filtration of  the mixture of  this ash and water normally has a brown  colour  can  emulsify  oil,  thus  producing  an  emulsion with  it.  It  is  slippery  to  touch, giving  an  impression  that  it  is  alkali. In Akwa Ibom State, Nigeria, this filtrate is used in preparing a local delicacy known as “Otong” which is used in eating meat, drinking of palm wine and can be used to spice soup. Otong, which looks like an emulsion is also slippery  to  touch  just  like soap, suggesting  that  the  reaction that produced  it may have been a  saponification  reaction. Saponification is a process that produces soap, usually from fats and lye.  In  technical  terms,  saponification  involves  base  (usually  caustic  soda NaOH)  hydrolysis  of  triglycerides, which are esters of fatty acids,  to  form  the  sodium  salt  of  a carboxylate (Ababio, 1993).

 

Oil palm empty fruit bunch is one of the byproducts left in the palm oil mill. This residue cause environmental pollution problems and spread diseases. Burning of EFB is now prohibited by regulations to prevent air pollution (Hamdan, Tarmizi and Mohd, 1998). The EFB is now used mainly as mulch materials placed around young palms, to control weeds, prevent erosion and maintain soil moisture. However, due to the current labor shortage, the transportation and distribution of EFB in the field is becoming more expensive. There is a growing interest in composting EFB, in order to add value and also to reduce the volume to make application easier (Thambirajah, Zulkifli and Hashim, 1995). Other researches stated that oil palm empty fruit bunch is a lignocellulosic source which is available as a substrate in cellulase production (Rajoka and Malik, 1997).

 

The incorporation of empty fruit bunch (EFB) into polymers to obtain cost reduction and reinforcement has been reported by various workers. Rozman, et al. (2001) investigated the mechanical properties of polypropylene/EFB composites and found that EFB has high tensile modulus, but low tensile strength. Abdul, Siti, Mohd and Omar ( 2006)  reported that modified EFB has improved the mechanical properties and water resistance of the polyester/EFB composites. Ridzuan, Shaler and Jamaludin (2002) reported that EFB is possibly suitable for medium density fibreboard (MDF). Pre-treatment of the fibre to remove its residual oil significantly improved the MDF properties and eliminated the delamination during consolidation of the panels. For removing the oil, sodium hydroxide (NaOH) is more effective than water, but a poorer fibre was obtained with a higher bulk density which also reduced the mechanical and physical properties. Ismail, Rosnah and Rozman (1997) reported that the adhesion between oil palm fibre and rubber matrix is poor but it can be modified by a treatment at high temperatures and various bonding agents. According to Aznizam and Azman (2003), there were reductions of the impact strength from the incorporation of EFB into the unmodified and modified unplasticised poly (vinyl chloride).

 

Biodegradation is the process by which organic substances are broken down into smaller compounds by the enzymes produced by micro-organisms. The micro-organisms transform the substance through metabolic or enzymatic processes. Biodegradation processes vary greatly, but frequently the final product of the degradation is carbon dioxide or methane. Organic material can be degraded aerobically, with oxygen, or anaerobically, without oxygen. Biodegradable matter is generally organic material such as plant and animal matter and other substances originating from living organisms, or artificial materials that are similar enough to plant and animal matter to be put to use by microorganisms. Some microorganisms have the astonishing, naturally occurring, microbial catabolic diversity to degrade, transform or accumulate a huge range of compounds including hydrocarbons, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), pharmaceutical substances, radionuclides and metals (Gross and Kalra, 2002).

 

Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Organic waste such as dead plant and animal material, animal dung and kitchen waste can be converted into a gaseous fuel called biogas. The gas is produced by anaerobic digestion of fermentation of biodegradable materials. Anaerobic decomposition occurs when the anaerobic microbes are dominant over the aerobic microbes. Biodegradable wastes are degraded in the absence of oxygen through the process of anaerobic digestion. The anaerobic decomposition of organic substances may be classified into four steps: hydrolysis, acid formation, acetate formation and methane formation. In the first two steps the organic substances are liquefied and decomposed (O’Loughlin, Traina and Sims, 2000). Their proper conversion into methane takes place in the last two steps of decomposition. The individual steps do not only differ from each other as regards the microorganisms participating and the products formed but also essentially by the environmental conditions required.

 

Biogas is practically produced as landfill gas or digester gas. A biogas plant is a name often given to an anaerobic digester that treats these biodegradable materials. The oil palm EFB is a non wood lignocellulosic material, which can be utilized as a renewable energy source for biogas production. The gas comprises primarily of methane (CH4) and carbon dioxide (CO2), and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes (Wieland, 2011). These gases can be combusted or oxidised with oxygen, releasing energy which allows biogas to be used as fuel. Biogas can be used in any country for any heating purpose, such as cooking. It can also be used in anaerobic digester where it is typically used in a gas engine to convert the energy in the gas into electricity and heat. Biogas can be compressed, much like natural gas, and used to power motor vehicles. In the UK, for example, biogas is estimated to have the potential to replace around 17% of vehicle fuel. Biogas is a renewable fuel, so it qualifies for renewable energy subsidies in some part of the world (Richards, et al., 1994).

 

  • Justification of Study

Since empty oil palm fruit bunches are extensively used in the rural communities of Akwa Ibom State as fertilizers (or soil conditioners), especially in pineapple and oil palm tree plantations, the analysis of its NPK value and the microbiology of its decomposition may help to recommend its use as fertilizer.

1.2      Objectives of Study

This work was aimed at investigating the types of microorganisms found at different stages of the biodegradation process of EFB of oil palm. To achieve this, some specific objectives were extensively assessed. They included:

  • To ascertain the microbial content of EFB at each stages of decomposition process for ten months at three weeks interval.
  • To assess the physicochemical composition of the EFB of oil palm
  • To assess the nutritional composition of the EFB of oil palm
  • To assess the gas production potentials of EFB using bio-digester.