Study of the feasibility of a rice husk recycling scheme in Japan to produce silica fertilizer for rice plants

Ryoko Sekifuji,Masafumi Tateda

doi:10.1186/s42834-019-0011-x

Abstract

Rice husks are resources that should be recycled in a sustainable way, thus creating a win-win relationship between stakeholders, consumers, and society. Silica is a very valuable material and used for many industrial purposes. A Rice husk contains 20% of silica by weight, and can therefore be considered a biological silica ore. To recycle rice husks in a sustainable way, the ash produced from burning rice husks must also be used as a resource. In this study, based on the concept that rice husk ash should be recycled as silica fertilizer, we compared the economic feasibility of two recycling systems: Heat recovery from hot water and generation of electricity from hot water. Questionnaires were also conducted regarding farmers’ expectations of silica fertilizer made from rice husk ash. We found that the system involving heat recovery from hot water was sustainable; however, generating electricity from hot water was cost-prohibitive. It must be noted that the validity of this result might be limited to Japan, where electricity generation is highly regulated. On the other hand, areas that already struggle to dispose of their rice husks should consider using rice husks to produce energy.

Highlights

Renewable energy is the key to creating a sustainable society
At the Local Agriculture Association Imizuno (LAAI), half of the annual 1.5 kt is used for floor bedding for domestic animals and materials for underdrain in paddy fields, but several hundred thousand USD are spent to dispose of rice husks
To evaluate the sustainability and feasibility of the two routes (Routes 1 and 2), their operating costs were compared. The two processes both produce ash; using this ash for silica fertilizer is the basic concept of rice husk recycling, and according to the results shown in Fig. 5c, the ash must be pelletized

Summary

Introduction

Renewable energy is the key to creating a sustainable society. Biomass is one of many sources of renewable energy. On the other hand, are generated every year and are a suitable form of renewable energy. That rice husks and straws are approximately 20 and 5% silica, respectively. This implies that rice plants need silica to grow, which is why rice plants absorb amorphous silica that is dissolved in irrigation water. If enough silica is not available to rice plants, they do not grow well and fail to stand straight up in paddy fields.

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Methods

Results

Conclusion