Rice husk (RH), an agricultural waste, is abundantly available in rice producing countries like China, India, Bangladesh, Brazil, US, Cambodia, Vietnam, Myanmar, and South East Asia. Despite the massive amount of annual production worldwide, so far RHs have been recycled only for low-value applications. In recent years, many rice mills in rice producing countries have started using RH for the energy production for mill operations as well as household lighting in rural regions. Burning of RHs produces the rice husk ash (RHA). The disposal in landfills or open fields can be problematic and may cause a serious environmental and human health related problems due to the low bulk density of RHA. Several ways are being thought of for disposing RHA by making its commercial use. The amorphous silica forms the main component (83–90%) of RHA. The amorphous silica rich RHA has wide range of applications. High-value applications and current research investigations such as the use of RHA in manufacturing of silica gels, silicon chip, synthesis of activated carbon and silica, production of light weight construction materials and insulation, catalysts, zeolites, ingredients for lithium ion batteries, graphene, energy storage/capacitor, carbon capture, and in drug delivery vehicles are presented. Use of RHA in potential future applications is also discussed. It is suggested that the amorphous silica rich RHA could become a potential resource of low cost precursor for the production of value-added silica based materials for practical applications.

Potential applications of rice husk ash waste from rice husk biomass power plant

As a staple food for much of the world, rice production is widespread. However, it also results in the generation of large quantities of non-food biomass, primarily in the form of straw and husks. Although they have been little utilized and much rice straw is still simply burned, these lignocellulosic materials potentially have considerable values. This review considers the composition of rice straw and husks, the various processes involved in the production of valuable products, and a range of uses to which they can be put. These include agricultural amendments, energy production, environmental adsorbents, construction materials, and various speciality products.

Utilization of Waste Straw and Husks from Rice Production: A Review

Characterization of rice husk ash produced using different biomass combustion techniques for energy

Applications of rice husk ash as green and sustainable biomass

Amid COVID-19, there have been rampant increase in the use of Personal Protective Equipment (PPE) kits by frontline health and sanitation communities, to reduce the likelihoods of infections. The used PPE kits, potentially being infectious, pose a threat to human health, terrestrial, and marine ecosystems, if not scientifically handled and disposed. However, with stressed resources on treatment facilities and lack of training to the health and sanitation workers, it becomes vital to vet different options for PPE kits disposal, to promote environmentally sound management of waste. Given the various technology options available for treatment and disposal of COVID-19 patients waste, Life Cycle Assessment, i.e., cradle to grave analysis of PPE provides essential guidance in identifying the environmentally sound alternatives. In the present work, Life Cycle Assessment of PPE kits has been performed using GaBi version 8.7 under two disposal scenarios, namely landfill and incineration (both centralized and decentralized) for six environmental impact categories covering overall impacts on both terrestrial and marine ecosystems, which includes Global Warming Potential (GWP), Human Toxicity Potential (HTP), Eutrophication Potential (EP), Acidification Potential (AP), Freshwater Aquatic Ecotoxicity Potential (FAETP) and Photochemical Ozone Depletion Potential (POCP). Considering the inventories of PPE kits, disposal of PPE bodysuit has the maximum impact, followed by gloves and goggles, in terms of GWP. The use of metal strips in face-mask has shown the most significant HTP impact. The incineration process (centralized-3816 kg CO2 eq. and decentralized-3813 kg CO2 eq.) showed high GWP but significantly reduced impact w.r.t. AP, EP, FAETP, POCP and HTP, when compared to disposal in a landfill, resulting in the high overall impact of landfill disposal compared to incineration. The decentralized incineration has emerged as environmentally sound management option compared to centralized incinerator among all the impact categories, also the environmental impact by transportation is significant (2.76 kg CO2 eq.) and cannot be neglected for long-distance transportation. Present findings can help the regulatory authority to delineate action steps for safe disposal of PPE kits.

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COVID-19 Creating another problem? Sustainable solution for PPE disposal through LCA approach.

Review of the rice production cycle: by-products and the main applications focusing on rice husk combustion and ash recycling.

In life cycle assessment (LCA), environmental impacts are classified according to the methodology used. Several life cycle impact assessment (LCIA) methods are currently used, and the method selected and the particulars thereof may influence the results obtained. This study characterized the main LCIA methods used and the most relevant categories of environmental impact. In total, 87 articles were initially retrieved using relevant keywords. After screening, 11 articles were shown to address the topic of study and were reviewed. The results showed that CML is the most widely used method. The main environmental impact category was global warming potential followed by acidification. Studies using LCA depend on the confirmation of the efficacy of the methods in the effort to represent and assess impacts in different regions of the world.

https://www.intechopen.com/citation-pdf-url/65112

Suggestion of Life Cycle Impact Assessment Methodology: Selection Criteria for Environmental Impact Categories

The construction industry causes significant negative environmental impact, partly due to the vast amounts of building materials used, and rice husk ash (RHA) is a solid waste produced in thermal power stations with potential applications as a partial replacement to Portland cement. Due to the increasing demand for research on environmental issues, the life-cycle approach emerges as an important tool in such investigations. This study evaluates the environmental performance of RHA as a replacement material for cement during the life-cycle of concrete. Environmental aspects and impacts associated with the combustion of rice husk biomass in a grate furnace and in a fluidized bed reactor, the transportation of the RHA produced, and its use in concrete production were evaluated. The most significant environmental impact caused by RHA production processes was global warming potential. The replacement of 20% Portland cement by RHA produced by combustion on fluidized bed reduced CO 2eq emissions by 24%. Even though this ash type had to be transported for 400 km to its destination, its use remained environmentally advantageous. But the replacement of 20% Portland cement by RHA produced by combustion on a grate furnace led to a reduction of only 7.7% in CO 2eq emissions.

Magali Rejane Rigon

Papers

Review of the rice production cycle: by-products and the main applications focusing on rice husk combustion and ash recycling.

Suggestion of Life Cycle Impact Assessment Methodology: Selection Criteria for Environmental Impact Categories

Co2 emission assessment for rice husk ash in concrete on environmental approach