**3. Results and discussion**

**Figure 2** illustrates the variation of voltage generation with time when using the feedstock waste as an organic waste in the MFC. It was found that when the cow dung and chicken dropping were used then the voltage generation was increasing sharply during the initial time. After one week the peak voltage reach at 450 mV and

#### **Figure 2.**

*Variation of voltage generation with duration by using live stock waste.*

340 mV for the cow dung and the chicken droppings, respectively. It was also found that the cow dung generated more voltage than the chicken dropping. The organic content of cow dung was higher than the chicken dropping. This could be a reason why the voltage is higher while using the cow dung. Nevertheless, both feedstock waste can be used for the bioelectricity generation in the microbial fuel cell. The management of the feedstock waste was a great challenge for many years all over the world. The biogas generation is one option for recycling this waste however to setup a biogas plant is another big challenge in the urban area and the area where is densely populated. The use of cow dung and the chicken dropping in MFC as a substrate can be a great help for the future resource recovery in the future. The future research will be needed to control the smell from the MFC to make it more practicable for the household applications. The cost is significantly small in this system while comparing the biogas system. The feedstock waste can cause many environmental problems in the developing countries. The mismanagement of this waste is causing various environmental pollution such as water pollution and the soil pollution. In the future, if this feedstock can be used as the organic substance of the MFC system and generate bioelectricity, then it will be a source a resource. Many developing countries need to generate electricity for their development even in small amount.

**Figure 3** shows the variation of the voltage with duration while using food waste and the fruit waste in the single chamber microbial fuel cell. It was found that when fruit waste was used then the MFC system can generate more electricity by comparing with the food waste. The fruit waste which were collected from the student's cafeteria contained a lot of fruit sections which were rich in sugar and carbohydrates. This sugar and the carbohydrates are the main source of energy for the electroactive bacteria. On the other hand, the food waste which are mainly comprised of the vegetable leftover and the other food remaining were not rich in sugar content and the carbohydrate content. This reason has influenced the result of the voltage generation while using the food waste and the fruit waste. The peak voltage reach at 380 mV and 300 mV when used as biomass in MFC in the fruit waste and food waste, respectively. While the voltage generation is lower when the food waste was used, it was also generated significant amount of voltage. This result reveals that the food waste which are currently disposed and burnt in the incineration plants in Japan can be recycled to generate bioelectricity in the MFC system.

**Figure 4** illustrates that voltage generation with duration while using rice bran and the leaf waste. It was found that the bioelectricity can be generated from the rice bran

#### **Figure 3.**

*Variation of voltage generation with duration by using food waste and fruit waste.*

**Figure 4.** *Variation of voltage generation with duration by using rice bran and leaf waste.*

and the leaf waste. The rice bran is produced in most of the time it was not reused or recycled in Japan. So, the use of this is very important for the bioelectricity generation in the MFC system. The garden waste often includes the dead leaves. Many times, this garden waste was not recycled and burnt with the other burnable waste. In this research this leaf can be used as the potential biomass in the MFC system. The carbon nitrogen ratio is very important for the microbial growth and the other activities for the best performance of MFC. However, this study showed that the voltage generation can be well even the garden waste was used in the MFC system. The peak voltage reached at 320 mV and 300 mV when using the rice bran and leaf waste, respectively. The interesting thig is that for the case of rice bran, the voltage generation was becoming constant after 8 days. The probable reason for that, the amount of food is depleted for the bacteria and the further biodegradation was not possible. The voltage generation by using the leaf mold decreased gradually after it reached the peak. The probable reason of this type of trend could be the substrates and the microbial degradation inside the biomass. As all the other factors are constant such as temperature, moisture content and sunlight, so it can be said that the organic content of the substances from the organic waste has the main influence to the voltage generation in this

#### *Bioelectricity from Organic Solid Waste DOI: http://dx.doi.org/10.5772/intechopen.95297*

study. Nevertheless, the reason of this trend is, the organic waste from rice production and the garden waste can be used as a biomass in the MFC system for bioelectricity generation. In this research, the additional bacteria or food for the bacteria were not used to make the system uniform and compare it carefully. As a result, the electricity generation is the affected by the organic waste compositions mainly.

There are several types of organic waste all over the world. The management of this organic waste is always a great challenge for the people. So, the researchers are conducting their research to find out the innovative solutions to get rid of this problem. It is true that the MFC system needs to be more studied before it is practically used. The weather factors and the activities of the bacteria will be the major challenge in the future for the sustainable application in the real world. It is necessary to check the various factors which will be affecting in the field application of this system without any delay.

Resource recovery from organic waste is a long time due for the human society. The depletion of fossil fuels, global warming and climate change has increased the demand to find a new way to get rid of energy problems. The waste to energy is a popular term among the researchers all over the world. In these circumstances, the bioelectricity generation form the various organic waste is the very important part of advancement in this field.

One of the objectives of this experiment is to use the by-products from generating bioelectricity with MFCs of kitchen garbage and bamboo waste as soil conditioner or organic fertilizer in the agricultural fields. Hence, it is important to examine the values of different nutrients as presented in **Figure 5** [10]. Decomposition of organic matter is brought about by micro-organisms that use the carbon as a source of energy and nitrogen for building cell structure. From the results of both MFCs, nitrogen (N), phosphorus (P) and potassium (K) in the soil after bioelectricity generation were found to be in the range of 1.5–1.7%, 0.6–0.8% and 1.3–1.7% respectively, which is similar to the value of compost yielded by others [11]. It was observed that the values of nutrients, namely nitrogen, phosphorus, and potassium, were very similar to the soil reported in other countries [11]. As a result, the decomposed sample can be used as potential fertilizer or soil conditioner, offering a resolution to the problem of organic matter depletion in soil across the globe. Solid waste creation is a global dilemma due to development and industrialization. About 1.3 billion metric tons of municipal solid waste (MSW) is generated annually in the world and this quantity is expected to increase about 2.2 billion tons by 2025 [12–17]. The important thing is that the organic waste is all zero cost materials. It must be reused to get some resource for the future sustainable society.

**Figure 5.** *Nutrient content of the by-products of bioelectricity generation.*
