2.5.4 What is composting?

Compost is a mixture of biodegradable organic matter such as straw, husks, tree bark, animal waste products and organic animal/plant matter (excluding sludge and fish organs) that are accumulated or mixed, and decomposed by heat. However sludge and fish organs may be considered compost if properly processed.

2.5.5 Basic principles of composting

Composting is the process of accumulating, mixing and aerating organic matter to decompose them with aerobic bacteria inside the material, evaporate the moisture generated by the heat from decomposition, and sterilize or make the harmful microbes or weed seeds inactive, to render the compost mixture safe and hygienic. Figure 5.7.1 shows the composting process. Composting offers the advantages of: (1) being easy to handle by hygienically-minded users since it eliminates noxious odors and the sense of handling biological waste products, (2) producing nutrients including the correct amount of elements for safe and high quality fertilizer for soil and crops, and (3) contributing to create a society that recycles its resources.

Evaporation

Fig. 5.7.1. Concept image of composting process.

2.5.6 Basic elements of composting

Composting is basically made up of (a) preprocessing, (a) fermentation processing, and (c)

product forming processing.

(a) Preprocessing

Preprocessing requires equipment for adjusting factors such as the moisture and organic matter, particle sizes, and aeration to make compost with the desired properties. When starting the composting, the moisture must usually be adjusted between 55 to 70 % and good aeration must be provided. This preprocessing includes additive methods (addition of adjustment materials such as shell, husks, sawdust, and chips), return methods (returning the product compost and mix with composting feedstock), and drying methods (drying using external energy).

(b) Fermentation

Fermentation requires a fermenting tank, aeration equipment and hydrolysis equipment. The fermentation tank decomposes organic matter and emits heat to raise the temperature of material accumulated in the fermentation tank so that conditions to produce safe and hygienic compost is attained by raising the temperature of the entire compost material to 65°C or higher and maintaining that temperature for 48 h or more. Fermentation methods are broadly grouped into accumulation methods and mechanical return methods. In the accumulation methods, materials such as compost, adjustment materials, and returned compost are accumulated on the floor and then repeatedly turned as needed with a shovel loader, etc. In the mechanical return method, an agitating device having a material loading slot and drainage slot for mixing the material is installed on the upper side wall of the fermentation tank. The aeration equipment maintains the material at a uniform aerobic state and provides ventilation to make the moisture evaporate from the material simultaneous with causing fermentation. The hydrolysis equipment supplies water to the material to ensure continued aerobic fermentation since microbial activity in the material ceases when the moisture in the material falls below 40%.

(c) Product forming process

The product forming process includes mechanical sorting and bagging/packing equipment for enhancing the product value and making the product compost easier to handle. Other facilities may include deodorizing equipment as part of environmental measures.

Lao PDR is a mountainous country with a population of about 5.6 million, over 80% of which lives in rural areas and is engaged in rice-based agriculture and harvesting of forest products. The narrowly based economy is one of the least developed in Asia with an approximate per capita Gross National Product of around US$ 500 per annum ( 2006 )

The Main Economic in Laos is from the Agriculture, Forestry, Power Generation, Mining, Small industries and agriculture is 42.2 % of the Gross Domestic Product, while the Industry is 31.5 % , Services 25.4 % and Import duties 0.9 % ( in 2006 ) .

Lao PDR is endowed with significant indigenous energy resources for electricity generation. Hydropower is the most abundant and cost-effective form. The energy resources range from traditional energy source such as fuel-wood to coal and hydropower. The forest areas which cover about 40 % of total land are a potential source for substantial traditional energy supplies.

The Lao power sector is in the good progress stage as 54.1 % of the population having access to electricity in 2006 . but the main energy consumption in Laos comes from fuelwood for cooking.

In order to meet the government target for the increasing the households electrification ration to be 70 % of total households in 2010 and 90% in 2020 , the Government set up the Power Sector Policy :

1. Maintain and expand an affordable, reliable and sustainable electricity supply in Lao PDR to promote economic and social development;

2. Promote power generation for export to provide revenues to meet GOL development objectives;

3. Develop and enhance legal and regulatory framework to effectively direct and facilitate power development; and

4. Strengthen institutions and institutional structures to clarify responsibilities, strengthen commercial functions and streamline administration

In order to meet those targets and Policies, now a day there are more than 50 MOU for the hydropower development with the capacity from 5 — 1080 MW and 6 projects are under construction, if we look on those hydropower development plan, we could see that there are many waste wood in the reservoirs need to be clear and if we have the good technologies and investment capital then we could construct biomass cogeneration projects in Laos.

Lao PDR import 100 % fossil fuels, at the present there are 3 companies to conduct the survey for the natural gas and oil and it takes about 10 years for getting all information and for the production of natural gas and oil ( if feasible ) , for reduction of import fuel and high efficiency fossil fuel consumption, the government of Laos also support the biofuel as biodiesel from the Jatropha and palm oil and bioethanol from the sugarcane.

After the government announced for promotion of biofuel, the are some companies started the business by plantation of Jatropha to produce the bio diesel, the biggest investor is Kolao Farm company, their target is plant the Jatropha 40.000 hac , the factory is under construction, it is far from the Vientiane Municipality about 70 km.

The second company is LaoBiodiesel company just started the construction of the factory in Champasak province on 10 March 2008 and their plantation is 100 hac for the Jatropha.

There are two companies to invest on the palm oil, the first one in Champsak province with the plantation of 25 hac, this company started in 2006 and the second one in Bolikhamsay province with the plantation of 20 hac this company started in 2006 .

The other companies to invest on Jatropha for biodiesel are small plantation.

Under Lao — Thai cooperation of Energy sector, the Ministry of Energy of Thailand give one set of Biodiesel production equipment from Jatropha to Ministry of Energy and Mines for the demonstration.

The Promotion of biodiesel is much more popular than biothethanol because the investment cost and the technology of bioethanol is high and now there is only one small existing of sugar factory in Laos, there other two factories are under construction in Savannaketh province.

Because of there is no any document for the promotion of biofuel in Laos, the department of Electricity, Ministry of Energy and Mines requested New Energy and Industrial Technology Development Organization ( NEDO ) , Representative Office in Bangkok to support the finance to hire the Lao Institute of Renewable Energy in Laos ( LIRE ) to conduct the survey and drafted the recommendation for the Strategy and Policy for the Promotion of Biodiesel in Laos.

The target of the government to reduce the fossil fuel consumption 5 % by promotion of biodiesel production.

The details of Strategy and Policy will be developed more..

8.2.1 Outline of large scale biomethanation

Anaerobic digestion has been in practical use for a long time. Its industrial installations had started as early as in around 1900. Since then, the anaerobic digestion systems have been continuously improved and enlarged to treat a wide range of biomass wastes such as food industry wastewater/waste, garbage, livestock waste, night soil and sewage sludge among others.

8.2.2 Large-scale anaerobic digestion systems

A typical anaerobic digestion system in large-scale is depicted in Fig. 8.2.1. The function of each unit process is described below.

(a) Pre-treatment process

It is often required for an effective anaerobic digestion that the received biomass waste is conditioned in a pre-treatment process such as removal of foreign matters not suitable for anaerobic digestion, pulverization, dilution by water, thickening, and/or acid or alkali treatment. Some biomass wastes such as garbage, which is a mixture of various organic and inorganic matters, and, thus is not always consistent in its composition and properties, are subjected to mechanical and/or magnetic separation in order to get rid of indigestible materials such as metals and plastics. The separated biomass waste is pulverized and added with dilution water to prepare waste slurry for the next unit process.

(b) Slurry storage tank

Prepared slurry is temporarily stored in a slurry storage tank for leveling dairy fluctuations in both quality and quantity. If the ambient temperature is suitable, microbial activities of acidogens in the storage tank may increase. If this occurs, accumulation of organic acids in the slurry can cause a decrease in pH to as low as around 4. The slurry storage tank must be designed to resist corrosion due to such low pH conditions.

(c) Methane fermenter (anaerobic digester)

Three major functional microbial groups are active in the methane fermenter. These three functions that take place sequentially are; hydrolysis, acidogenesis and methanogenesis. The final products of the reactions are methane and carbon dioxide. The hydrolysis reaction is often the rate-limiting pathway of an anaerobic digestion process on not-readily biodegradable or recalcitrant biomass such as sewage sludge and ligneous biomass, whereas the methanogenesis is likely to be the rate-limiting pathway on readily biodegradable biomass such as garbage and starchy wastewater. In order to establish an efficient anaerobic digestion system, it is important to consider the rate-limiting pathway and to select the most suitable reactor design for the properties of anticipated biomass waste. For example, the overall rate of anaerobic digestion on readily biodegradable biomass waste heavily depends on the density of active methanogens in the reactor, thus the reactor should be designed to maximize the density or mass of the methanogens within the system.

(d) Fermentation wastewater treatment

Fermentation wastewater discharged from the anaerobic digester usually contains high concentrations of organic matters, nitrogen compounds and phosphorus compounds. The fermentation wastewater should be treated to reduce the concentrations of these pollutants to meet the standards for final discharge to a receiving body of water or sewer system. The most typical fermentation wastewater treatment system is the activated sludge process with tertiary treatment.

(e) Biogas utilization

Since most of the biomass wastes contain proteins (a source of nitrogen and sulfur) and sulfate salts, the biogas contains certain concentrations of hydrogen sulfide and ammonia. The biogas produced from sewage sludge, which sometimes contains a considerable amount of silicones, may contain siloxanes as well. Since these impurities can possibly cause damage to biogas utilization facilities such as a gas engine, gas boiler, gas turbine and fuel cell, and/or cause secondary air pollution, a biogas utilization unit process is often equipped with a desulfurization device and/or siloxane remover prior to the gas holding tank.

As an example of definition in law, Japanese case is shown below. On January 25, 2002, the Law on Special Measures for Facilitating the Use of New Energy Sources (New Energy Law) was partially amended, and biomass was for the first time recognized as a new energy source in Japan. Fig. 2.1.1 shows the position of biomass among other “new energies”. Formerly, biomass had been considered as merely a kind of renewable resources, but the amended law now sees it as an independent category of new energy. However, some wastes, such as paper waste, food waste, demolition waste, and black liquor, are considered to be recyclable resources as well according to circumstances, and they are not strictly classified.

2.1.2 Characteristics of biomass energy

Up to the 19th century, biomass in the form of firewood and charcoal was the main source of energy, but these were replaced by coal and oil in the 20th century. In the 21st century, however, biomass shows signs of being revived because of the following characteristics: it is renewable, it is storable and substitutive, it is abundant, and it is carbon neutral.

Agricultural residue refers to residue produced in fields or farm during harvesting and other activities. As energy resources, available agricultural residue includes those from cereals, rhizomic crops, and sugarcane. In addition, there is a huge amount and variety of vegetable residues could be produced that would not be considered as energy resources because it is difficult to collect them efficiently on a large scale.

Particleboard manufacture is a valuable process for recycling woody waste that might otherwise be landfilled or burned. The process permits blending recycled materials with fiber from other sources to achieve specific properties. For example, limiting shorter recycled elements to the core and using longer elements from other sources on the surface can improve strength. Particleboard manufacture is a mature industry in Japan, but there are opportunities for improving the efficiency of the process. As oil prices continue to increase, the costs for transportation, adhesives, and energy for plant operation continue to increase. Particleboard manufacturers must compete with other industries for woody raw materials. Some recent policies that focus on woody biomass for energy make the situation even worse. The Minister of Agriculture, Forestry and Fishery started a comprehensive program focusing on agricultural woody biomass resources, with clear goals for: 1) education, 2) technology development of transportation fuel such as bio-ethanol, 3) promotion and networking of local societies that use biomass resources, 4) research and development of technologies for using woody biomass and other potential natural resources, 5) initiatives for using biomass products and promoting recycling, and 6) technology transfer to other Asian countries. Most particleboard industries that use local woody wastes intend to improve efficiency by increasing their use of recycled material and supplementing energy for plant operation by burning material that is unsuitable for manufacturing particleboard.

Saccharine materials used for ethanol production at a large scale are juice and molasses of sugar cane and sugar beet. Molasses is a byproduct which is concentrated mother liquid after sugar crystallization. Sugar concentration of molasses is around 50% and contains glucose, fructose and sucrose as main sugar components. These saccharine materials are good substrate for ethanol fermentation by yeast and Zymomonas. A lot of cane juice is used for ethanol production in Brazil and India.

Popular ethanol fermentation process in Brazil is continuous or semi-continuous fermentation process called Melle-Boinot process in which yeast cells are recovered from beer through centrifuge and recycled to fermentation tank after sterilization of contaminated bacteria with dilute sulfuric acid at pH 3. Ethanol fermentation at high concentration of yeast cells can make beer containing 6 to 8 % of ethanol from cane juice (11-17% sugar concentration) in about 15 h of fermentation period. Molasses is used for fermentation after two-times dilution or mixing with cane juice or beet juice.

When fermentation yield is 82% (based on total sugar), and sugar concentration of molasses is 55%, the amount of molasses required to produce 1 m3 (kL) of 95% ethanol is 3.3 t-wet.

Unique saccharine materials are milk whey and citrus molasses. In dairy industry of New Zealand, for example, a large amount of milk whey containing about 4% lactose is discharged. They use the waste whey for ethanol fermentation to recover value-added byproduct and to reduce BOD.

A large amount of citrus peel is discharged in citrus juice manufacture. Secondary juice from citrus peel containing about 8% sugar and bitter components is concentrated to citrus molasses of sugar concentration of over 40% for ethanol production.

Biomass generation technology is compared with the other generation technology (coal fired, oil fired, LNG fired, hydropower, ocean thermal energy conversion, photovoltaic). The biomass power generation is defined as the scale that can manage as much as biomass grown by 30km2 afforestation in North America, Indonesia, and Brazil. Annual quantity of sending end generation and power station scale of each power station are shown in table 6.3.2.

The CO2 emission per 1kWh of each generation plant can be found dividing the sum of CO2 emission on power station construction and operation (fuel burning and maintenance repair) by the amount of total generated energy, assuming durability year of each generation plant. The durability of all power stations was defined as 30 years here.

Table 6.3.3 and Fig. 6.3.1 show each plant CO2 emission based on LCA. While facilities of biomass power generation have a similarity to thermal power generation by fossil fuel, CO2 emission per unit electricity of the biomass generation has a drastic reduction because CO2 emission on the biomass combustion is not counted. About CO2 emission, biomass power

generation is a highly competitive technology to the other renewable energy generation.

Fig. 6.3.1. Unit CO2 Emission of Various Power Generation.

There are two seasons of paddy planted in Malaysia. The main season refers to the period of paddy planting from 1st of August to 28th February and off season covers the period of paddy planting from 31st March to 31st July of the year. The total paddy planted areas for Malaysia in the year 2000 was about 600,287 hectares and producing 2,050,306 tones of paddy. Malaysia is about 65% self sufficient in rice supply and another 35% is imported from Thailand and Vietnam. Paddy straw and rice husk are generated as biomass residue during the harvested and milling processes. The paddy straw is left in the paddy field and the rice husk is generated in the rice mill. Both of the biomass are discharged by landfill and open burning. Only a small quantity of rice husk is used for energy generation and other application such as silica production and composting.

It is assumed that only 2% of the rice husk is used for energy production. The balance is treated as landfill method. The paddy straw is usually burned in the open burning areas. The amount of rice husk and paddy straw generated in future are dependent on the planted area, the paddy yield and government policies on agriculture. The government plans to increase the yield from the existing rate to 10 metric tonne per hectare in the future. With this target value more rice husk and paddy straw is available for biomass CHP plant. The issue of solid biomass is difficulties in transportation and handling due to very low density and abrasive nature of the material.

Structuring of a network for the purpose of sharing information among members related to Asian biomass and developing mutual understanding is important. There are two streams in this term. The one is Biomass Asia Forum, which was organized mainly by the Ministry of Agriculture, Forestry, and Fishery, Japan, and the other is Biomass ASEAN Project, which is proceeded mainly by the National Institute of Advanced and Industrial Science and Technology, Japan (AIST), and Japan International Research Center for Agricultural Science (JIRCAS) with the subsidies from the Ministry of Education, Culture, Sports, Science and Technology, Japan. In the year of 2004, these two projects started independently, but soon it was notice that both projects have similar goals, and it was decided to have a joint-workshop, which was the 1st Biomass Asia Workshop, held in January, 2005, in Tokyo and Tsukuba, Japan. In December, 2005, the 2nd Biomass Asia Workshop was held in Bangkok, Thailand, and Biomass Asia Forum was held in January, 2006 in Tokyo. Through these workshops and forum, the situation of biomass in Asian countries was studied, and the purpose of its effective use was discussed. Based on these concept, the network development was discussed at the 3rd Biomass Asia Workshop in Novemer, 2006. This flow is shown in Fig. 1.

The 4th Biomass Asia Workshop was held in November, 2007 in Shah Alam, Malaysia. The 5th workshop is to be held in China.

To overview the trend of recent biomass activities, the program of the 4th Biomass Asia Workshop is also shown here.

WS (Biomass ASEAN) Forum (MAFF support)

2005.1

Organization for Asian Biomass

Fig. A1.2.1 Events regarding the networking on Asian Biomass utilization.