Slurry Movement

As the global energy demand rapidly grows, the need for energy resources is also growing. As of now, around 88% of the demand is met by utilizing fossil fuels. Scenarios have indicated that the energy demand will increase during this century by two or three times (IEA, 2006). Alongside the increasing energy demand, efforts put into finding new, renewable, and energy conservation have been arising. Biogas is one of the renewable energy resources available from biomass that has the potential to be implemented in Indonesia. Fossil fuels are named because of their origin, which is the accumulation of organic matter on the earth’s surface for long periods of time. The accumulation of organic matter will eventually be covered by sand and form a

(2012) mentioned that in certain condition water should be added to the raw material to generate slurry. The resulting slurry must also meet the requirements, not too thick or too thin. Consequence of a heavily diluted material is the high probability of creation of phases, which will reduce degradation efficiency. On the other hand, if the slurry is too thick, stirring may become more difficult aside from it serving as a block for the resulting gas flow to the top of the digester. However, the ability of the digester system to handle the density of the slurry ranges from 10-25% according to each system’s way of work. For the best pH value in biogas production, Abbasi et al. (2012) stated that during input, the mixture should be between 6 to 7. Then during the initial period of anerobic digestion, the pH will decrease due to the amount of organic acids produced. Ammonia, from nitrogen digestion, will be produced as the anaerobic digestion process continues; the consequent effect will be the increasing of the pH. The end pH for anaerobic digestion for biogas should be 7.2 to

Nowadays, along with more farms being opened, the amount of animal manure excreted daily also arises. It is composed of organic matter and some residual from the livestock’s digestive systems. Therefore, animal manure is rich in nutrients. However, if not managed efficiently, the large amounts of animal manure and slurries produced today by the animal breeding sector as well as the wet organic waste streams is representative for constant pollution risk with the potential of bringing negative impacts on the environment (Holm-Nielsen, Al Seadi, & Oleskowicz-Popiel, 2009). According to Holm-Nielsen et al. (2009), The objectives of conducting anaerobic digestion on animal manure is to convert organic residues into two main products, they are biogas (a form of bioenergy) and to generate digestate (leftover of anerobic digestion). Sustainability may be achieved by biological treatment of solid, liquid, and gaseous wastes. Product-oriented bioconversion processes in facilities by making use of advanced technology can treat biodegradable wastes. Anaerobic digestion, fermentation, and composting is the most common methods to treat biodegradable wastes (Jereb,